WorldWideScience

Sample records for total leaf respiration

  1. Global variability in leaf respiration in relation to climate and leaf traits

    Science.gov (United States)

    Atkin, Owen K.

    2015-04-01

    Leaf respiration plays a vital role in regulating ecosystem functioning and the Earth's climate. Because of this, it is imperative that that Earth-system, climate and ecosystem-level models be able to accurately predict variations in rates of leaf respiration. In the field of photosynthesis research, the F/vC/B model has enabled modellers to accurately predict variations in photosynthesis through time and space. By contrast, we lack an equivalent biochemical model to predict variations in leaf respiration. Consequently, we need to rely on phenomenological approaches to model variations in respiration across the Earth's surface. Such approaches require that we develop a thorough understanding of how rates of respiration vary among species and whether global environmental gradients play a role in determining variations in leaf respiration. Dealing with these issues requires that data sets be assembled on rates of leaf respiration in biomes across the Earth's surface. In this talk, I will use a newly-assembled global database on leaf respiration and associated traits (including photosynthesis) to highlight variation in leaf respiration (and the balance between respiration and photosynthesis) across global gradients in growth temperature and aridity.

  2. Leaf respiration at different canopy positions in sweetgum (Liquidambar styraciflua) grown in ambient and elevated concentrations of carbon dioxide in the field

    International Nuclear Information System (INIS)

    Tissue, D. T.; Lewis, J. D.; Wullschleger, S. D.; Amthro, J. S.; Griffin, K. L.; Anderson, O. R.

    2002-01-01

    The effects of elevated carbon dioxide and canopy position on leaf respiration in sweetgum trees in a closed canopy forest were measured in an effort to determine if, and why, enriched atmospheric carbon dioxide might affect leaf respiration in sweetgum. To account for the dark respiratory response to growth in elevated carbon dioxide, cell ultrastructure and cytochrome c oxidase activity in leaves were measured at different seasonal growth periods. Leaf respiration under light conditions was also estimated to determine whether elevated carbon dioxide affected daytime respiration. Results showed that long-term exposure to elevated carbon dioxide did not effect night-time or day- time respiration in trees grown in a plantation in the field. Canopy position affected night-time respiration partially, through the effects on leaf soluble sugar, starch, nitrogen and leaf mass per unit area. In carbon dioxide partial pressure the effects of canopy position were insignificant. It was concluded that elevated carbon dioxide does not directly impact leaf respiration in sweetgum and assuming no changes in leaf nitrogen or leaf chemical composition, the long-term effects on respiration in this species will be minimal. 50 refs., 4 tabs., 3 figs

  3. Convergence in the temperature response of leaf respiration across biomes and plant functional types.

    Science.gov (United States)

    Heskel, Mary A; O'Sullivan, Odhran S; Reich, Peter B; Tjoelker, Mark G; Weerasinghe, Lasantha K; Penillard, Aurore; Egerton, John J G; Creek, Danielle; Bloomfield, Keith J; Xiang, Jen; Sinca, Felipe; Stangl, Zsofia R; Martinez-de la Torre, Alberto; Griffin, Kevin L; Huntingford, Chris; Hurry, Vaughan; Meir, Patrick; Turnbull, Matthew H; Atkin, Owen K

    2016-04-05

    Plant respiration constitutes a massive carbon flux to the atmosphere, and a major control on the evolution of the global carbon cycle. It therefore has the potential to modulate levels of climate change due to the human burning of fossil fuels. Neither current physiological nor terrestrial biosphere models adequately describe its short-term temperature response, and even minor differences in the shape of the response curve can significantly impact estimates of ecosystem carbon release and/or storage. Given this, it is critical to establish whether there are predictable patterns in the shape of the respiration-temperature response curve, and thus in the intrinsic temperature sensitivity of respiration across the globe. Analyzing measurements in a comprehensive database for 231 species spanning 7 biomes, we demonstrate that temperature-dependent increases in leaf respiration do not follow a commonly used exponential function. Instead, we find a decelerating function as leaves warm, reflecting a declining sensitivity to higher temperatures that is remarkably uniform across all biomes and plant functional types. Such convergence in the temperature sensitivity of leaf respiration suggests that there are universally applicable controls on the temperature response of plant energy metabolism, such that a single new function can predict the temperature dependence of leaf respiration for global vegetation. This simple function enables straightforward description of plant respiration in the land-surface components of coupled earth system models. Our cross-biome analyses shows significant implications for such fluxes in cold climates, generally projecting lower values compared with previous estimates.

  4. Effects of elevated CO2 leaf diets on gypsy moth (Lepidoptera: Lymantriidae) respiration rates.

    Science.gov (United States)

    Foss, Anita R; Mattson, William J; Trier, Terry M

    2013-06-01

    Elevated levels of CO2 affect plant growth and leaf chemistry, which in turn can alter host plant suitability for insect herbivores. We examined the suitability of foliage from trees grown from seedlings since 1997 at Aspen FACE as diet for the gypsy moth (Lymantria dispar L.) Lepidoptera: Lymantriidae: paper birch (Betula papyrifera Marshall) in 2004-2005, and trembling aspen (Populus tremuloides Michaux) in 2006-2007, and measured consequent effects on larval respiration. Leaves were collected for diet and leaf chemistry (nutritional and secondary compound proxies) from trees grown under ambient (average 380 ppm) and elevated CO2 (average 560 ppm) conditions. Elevated CO2 did not significantly alter birch or aspen leaf chemistry compared with ambient levels with the exception that birch percent carbon in 2004 and aspen moisture content in 2006 were significantly lowered. Respiration rates were significantly higher (15-59%) for larvae reared on birch grown under elevated CO2 compared with ambient conditions, but were not different on two aspen clones, until larvae reached the fifth instar, when those consuming elevated CO2 leaves on clone 271 had lower (26%) respiration rates, and those consuming elevated CO2 leaves on clone 216 had higher (36%) respiration rates. However, elevated CO2 had no apparent effect on the respiration rates of pupae derived from larvae fed either birch or aspen leaves. Higher respiration rates for larvae fed diets grown under ambient or elevated CO2 demonstrates their lower efficiency of converting chemical energy of digested food stuffs extracted from such leaves into their biosynthetic processes.

  5. Relationships of leaf dark respiration to leaf nitrogen, specific leaf area and leaf life-span: a test across biomes and functional groups.

    Science.gov (United States)

    Reich, Peter B; Walters, Michael B; Ellsworth, David S; Vose, James M; Volin, John C; Gresham, Charles; Bowman, William D

    1998-05-01

    Based on prior evidence of coordinated multiple leaf trait scaling, we hypothesized that variation among species in leaf dark respiration rate (R d ) should scale with variation in traits such as leaf nitrogen (N), leaf life-span, specific leaf area (SLA), and net photosynthetic capacity (A max ). However, it is not known whether such scaling, if it exists, is similar among disparate biomes and plant functional types. We tested this idea by examining the interspecific relationships between R d measured at a standard temperature and leaf life-span, N, SLA and A max for 69 species from four functional groups (forbs, broad-leafed trees and shrubs, and needle-leafed conifers) in six biomes traversing the Americas: alpine tundra/subalpine forest, Colorado; cold temperate forest/grassland, Wisconsin; cool temperate forest, North Carolina; desert/shrubland, New Mexico; subtropical forest, South Carolina; and tropical rain forest, Amazonas, Venezuela. Area-based R d was positively related to area-based leaf N within functional groups and for all species pooled, but not when comparing among species within any site. At all sites, mass-based R d (R d-mass ) decreased sharply with increasing leaf life-span and was positively related to SLA and mass-based A max and leaf N (leaf N mass ). These intra-biome relationships were similar in shape and slope among sites, where in each case we compared species belonging to different plant functional groups. Significant R d-mass -N mass relationships were observed in all functional groups (pooled across sites), but the relationships differed, with higher R d at any given leaf N in functional groups (such as forbs) with higher SLA and shorter leaf life-span. Regardless of biome or functional group, R d-mass was well predicted by all combinations of leaf life-span, N mass and/or SLA (r 2 ≥ 0.79, P morphological, chemical and metabolic traits.

  6. Leaf photosynthesis and respiration of three bioenergy crops in relation to temperature and leaf nitrogen: how conserved are biochemical model parameters among crop species?

    Science.gov (United States)

    Archontoulis, S. V.; Yin, X.; Vos, J.; Danalatos, N. G.; Struik, P. C.

    2012-01-01

    Given the need for parallel increases in food and energy production from crops in the context of global change, crop simulation models and data sets to feed these models with photosynthesis and respiration parameters are increasingly important. This study provides information on photosynthesis and respiration for three energy crops (sunflower, kenaf, and cynara), reviews relevant information for five other crops (wheat, barley, cotton, tobacco, and grape), and assesses how conserved photosynthesis parameters are among crops. Using large data sets and optimization techniques, the C3 leaf photosynthesis model of Farquhar, von Caemmerer, and Berry (FvCB) and an empirical night respiration model for tested energy crops accounting for effects of temperature and leaf nitrogen were parameterized. Instead of the common approach of using information on net photosynthesis response to CO2 at the stomatal cavity (An–Ci), the model was parameterized by analysing the photosynthesis response to incident light intensity (An–Iinc). Convincing evidence is provided that the maximum Rubisco carboxylation rate or the maximum electron transport rate was very similar whether derived from An–Ci or from An–Iinc data sets. Parameters characterizing Rubisco limitation, electron transport limitation, the degree to which light inhibits leaf respiration, night respiration, and the minimum leaf nitrogen required for photosynthesis were then determined. Model predictions were validated against independent sets. Only a few FvCB parameters were conserved among crop species, thus species-specific FvCB model parameters are needed for crop modelling. Therefore, information from readily available but underexplored An–Iinc data should be re-analysed, thereby expanding the potential of combining classical photosynthetic data and the biochemical model. PMID:22021569

  7. Physiological Adjustments of Leaf Respiration to Atmospheric Warming in Betula alleghaniensis and Quercus rubra

    Energy Technology Data Exchange (ETDEWEB)

    Vollmar, A.; Gunderson, C.

    2006-01-01

    Global air temperatures are predicted to rise 1° to 4.5° Celsius by the year 2100. This climatic change is expected to have a great effect on the succession and migration of temperate deciduous forest species. Most physiologically based models of forest response to climatic change focus on the ecosystems as a whole instead of on individual tree species, assuming that the effects of warming on respiration are generally the same for each species, and that processes can not adjust to a changing climate. Experimental data suggest that physiological adjustments are possible, but there is a lack of data in deciduous species. In order to correctly model the effects of climate change on temperate species, species-specific respiration acclimation (adjustment) to rising temperatures is being determined in this experiment. Two temperate deciduous tree species Betula alleghaniensis (BA) and Quercus rubra (QR) were grown over a span of four years in open-top chambers and subjected to two different temperature treatments; ambient and ambient plus 4° Celsius (E4). Between 0530 hours and 1100 hours, respiration was measured over a range of leaf temperatures on several comparable, fully expanded leaves in each treatment. Circular punches were taken from the leaves and dried at 60°C to determine leaf mass per area (LMA). Respiration rates at a common temperature decreased by 15-18% in both species, and the entire resperation versus temperature curve shifted by at least 4°C, indicating a large degree of physiological acclimation. Foliar mass per area decreased with increasing growth temperature for both species. It can be concluded that there is a relationship between leaf respiration and foliar mass as it relates to respiratory acclimation, and that these two species had similar patterns of adjustment to warming.

  8. Global convergence in leaf respiration from estimates of thermal acclimation across time and space.

    Science.gov (United States)

    Vanderwel, Mark C; Slot, Martijn; Lichstein, Jeremy W; Reich, Peter B; Kattge, Jens; Atkin, Owen K; Bloomfield, Keith J; Tjoelker, Mark G; Kitajima, Kaoru

    2015-09-01

    Recent compilations of experimental and observational data have documented global temperature-dependent patterns of variation in leaf dark respiration (R), but it remains unclear whether local adjustments in respiration over time (through thermal acclimation) are consistent with the patterns in R found across geographical temperature gradients. We integrated results from two global empirical syntheses into a simple temperature-dependent respiration framework to compare the measured effects of respiration acclimation-over-time and variation-across-space to one another, and to a null model in which acclimation is ignored. Using these models, we projected the influence of thermal acclimation on: seasonal variation in R; spatial variation in mean annual R across a global temperature gradient; and future increases in R under climate change. The measured strength of acclimation-over-time produces differences in annual R across spatial temperature gradients that agree well with global variation-across-space. Our models further project that acclimation effects could potentially halve increases in R (compared with the null model) as the climate warms over the 21st Century. Convergence in global temperature-dependent patterns of R indicates that physiological adjustments arising from thermal acclimation are capable of explaining observed variation in leaf respiration at ambient growth temperatures across the globe. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  9. Transcriptional reprogramming and stimulation of leaf respiration by elevated CO2 concentration is diminished, but not eliminated, under limiting nitrogen supply.

    Science.gov (United States)

    Markelz, R J Cody; Lai, Lisa X; Vosseler, Lauren N; Leakey, Andrew D B

    2014-04-01

    Plant respiration responses to elevated CO2 concentration ( [CO2 ] ) have been studied for three decades without consensus about the mechanism of response. Positive effects of elevated [CO2 ] on leaf respiration have been attributed to greater substrate supply resulting from stimulated photosynthesis. Negative effects of elevated [CO2 ] on leaf respiration have been attributed to reduced demand for energy for protein turnover assumed to result from lower leaf N content. Arabidopsis thaliana was grown in ambient (370 ppm) and elevated (750 ppm) [CO2 ] with limiting and ample N availabilities. The stimulation of leaf dark respiration was attenuated in limiting N (+12%) compared with ample N supply (+30%). This response was associated with smaller stimulation of photosynthetic CO2 uptake, but not interactive effects of elevated CO2 and N supply on leaf protein, amino acids or specific leaf area. Elevated [CO2 ] also resulted in greater abundance of transcripts for many components of the respiratory pathway. A greater transcriptional response to elevated [CO2 ] was observed in ample N supply at midday versus midnight, consistent with reports that protein synthesis is greatest during the day. Greater foliar expression of respiratory genes under elevated [CO2 ] has now been observed in diverse herbaceous species, suggesting a widely conserved response. © 2013 John Wiley & Sons Ltd.

  10. Carbon Isotope Composition of Nighttime Leaf-Respired CO2 in the Agricultural-Pastoral Zone of the Songnen Plain, Northeast China

    Science.gov (United States)

    Cui, Haiying; Wang, Yunbo; Jiang, Qi; Chen, Shiping; Ma, Jian-Ying; Sun, Wei

    2015-01-01

    Variations in the carbon isotope signature of leaf dark-respired CO2 (δ13CR) within a single night is a widely observed phenomenon. However, it is unclear whether there are plant functional type differences with regard to the amplitude of the nighttime variation in δ13CR. These differences, if present, would be important for interpreting the short-term variations in the stable carbon signature of ecosystem respiration and the partitioning of carbon fluxes. To assess the plant functional type differences relating to the magnitude of the nighttime variation in δ13CR and the respiratory apparent fractionation, we measured the δ13CR, the leaf gas exchange, and the δ13C of the respiratory substrates of 22 species present in the agricultural-pastoral zone of the Songnen Plain, northeast China. The species studied were grouped into C3 and C4 plants, trees, grasses, and herbs. A significant nocturnal shift in δ13CR was detected in 20 of the studied species, with the magnitude of the shift ranging from 1‰ to 5.8‰. The magnitude of the nighttime variation in δ13CR was strongly correlated with the daytime cumulative carbon assimilation, which suggests that variation in δ13CR were influenced, to some extent, by changes in the contribution of malate decarboxylation to total respiratory CO2 flux. There were no differences in the magnitude of the nighttime variation in δ13CR between the C3 and C4 plants, as well as among the woody plants, herbs and graminoids. Leaf respired CO2 was enriched in 13C compared to biomass, soluble carbohydrates and lipids; however the magnitude of enrichment differed between 8 pm and 4 am, which were mainly caused by the changes in δ13CR. We also detected the plant functional type differences in respiratory apparent fractionation relative to biomass at 4 am, which suggests that caution should be exercised when using the δ13C of bulk leaf material as a proxy for the δ13C of leaf-respired CO2. PMID:26356083

  11. After more than a decade of soil moisture deficit, tropical rainforest trees maintain photosynthetic capacity, despite increased leaf respiration.

    Science.gov (United States)

    Rowland, Lucy; Lobo-do-Vale, Raquel L; Christoffersen, Bradley O; Melém, Eliane A; Kruijt, Bart; Vasconcelos, Steel S; Domingues, Tomas; Binks, Oliver J; Oliveira, Alex A R; Metcalfe, Daniel; da Costa, Antonio C L; Mencuccini, Maurizio; Meir, Patrick

    2015-12-01

    Determining climate change feedbacks from tropical rainforests requires an understanding of how carbon gain through photosynthesis and loss through respiration will be altered. One of the key changes that tropical rainforests may experience under future climate change scenarios is reduced soil moisture availability. In this study we examine if and how both leaf photosynthesis and leaf dark respiration acclimate following more than 12 years of experimental soil moisture deficit, via a through-fall exclusion experiment (TFE) in an eastern Amazonian rainforest. We find that experimentally drought-stressed trees and taxa maintain the same maximum leaf photosynthetic capacity as trees in corresponding control forest, independent of their susceptibility to drought-induced mortality. We hypothesize that photosynthetic capacity is maintained across all treatments and taxa to take advantage of short-lived periods of high moisture availability, when stomatal conductance (gs ) and photosynthesis can increase rapidly, potentially compensating for reduced assimilate supply at other times. Average leaf dark respiration (Rd ) was elevated in the TFE-treated forest trees relative to the control by 28.2 ± 2.8% (mean ± one standard error). This mean Rd value was dominated by a 48.5 ± 3.6% increase in the Rd of drought-sensitive taxa, and likely reflects the need for additional metabolic support required for stress-related repair, and hydraulic or osmotic maintenance processes. Following soil moisture deficit that is maintained for several years, our data suggest that changes in respiration drive greater shifts in the canopy carbon balance, than changes in photosynthetic capacity. © 2015 John Wiley & Sons Ltd.

  12. Separating rhizosphere respiration from total soil respiration in two larch plantations in northeastern China.

    Science.gov (United States)

    Jiang, Lifen; Shi, Fuchen; Li, Bo; Luo, Yiqi; Chen, Jiquan; Chen, Jiakuan

    2005-09-01

    The potential capacity of soil to sequester carbon in response to global warming is strongly regulated by the ratio of rhizosphere respiration to respiration by soil microbial decomposers, because of their different temperature sensitivities. To quantify relative contributions of rhizosphere respiration to total soil respiration as influenced by forest stand development, we conducted a trenching study in two larch (Larix gmelini (Rupr.) Rupr.) plantations, aged 17 and 31 years, in northeastern China. Four plots in each plantation were randomly selected and trenched in early May 2001. Soil surface CO2 effluxes both inside and outside the plots were measured from May 2001 to August 2002. Soil respiration (i.e., the CO2 effluxes outside the trenched plots) varied similarly in the two plantations from 0.8 micromol m(-2) s(-1) in winter to 6.0 micromol m(-2) s(-1) in summer. Rhizosphere respiration (i.e., CO2 efflux outside the trenched plots minus that inside the plots) varied from 0.2 to 2.0 micromol m(-2) s(-1) in the old forest and from 0.3 to 4.0 micromol m(-2) s(-1) in the young forest over the seasons. Rhizosphere respiration, on average, accounted for 25% of soil respiration in the old forest and 65% in the young forest. Rhizosphere and soil respiration were significantly correlated with soil temperature but not with soil water content. We conclude that the role forests play in regulating climate change may depend on their age.

  13. Scaling leaf respiration with nitrogen and phosphorus in tropical forests across two continents.

    Science.gov (United States)

    Rowland, Lucy; Zaragoza-Castells, Joana; Bloomfield, Keith J; Turnbull, Matthew H; Bonal, Damien; Burban, Benoit; Salinas, Norma; Cosio, Eric; Metcalfe, Daniel J; Ford, Andrew; Phillips, Oliver L; Atkin, Owen K; Meir, Patrick

    2017-05-01

    Leaf dark respiration (R dark ) represents an important component controlling the carbon balance in tropical forests. Here, we test how nitrogen (N) and phosphorus (P) affect R dark and its relationship with photosynthesis using three widely separated tropical forests which differ in soil fertility. R dark was measured on 431 rainforest canopy trees, from 182 species, in French Guiana, Peru and Australia. The variation in R dark was examined in relation to leaf N and P content, leaf structure and maximum photosynthetic rates at ambient and saturating atmospheric CO 2 concentration. We found that the site with the lowest fertility (French Guiana) exhibited greater rates of R dark per unit leaf N, P and photosynthesis. The data from Australia, for which there were no phylogenetic overlaps with the samples from the South American sites, yielded the most distinct relationships of R dark with the measured leaf traits. Our data indicate that no single universal scaling relationship accounts for variation in R dark across this large biogeographical space. Variability between sites in the absolute rates of R dark and the R dark  : photosynthesis ratio were driven by variations in N- and P-use efficiency, which were related to both taxonomic and environmental variability. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  14. Global variability in leaf respiration in relation to climate, plant functional types and leaf traits.

    Science.gov (United States)

    Atkin, Owen K; Bloomfield, Keith J; Reich, Peter B; Tjoelker, Mark G; Asner, Gregory P; Bonal, Damien; Bönisch, Gerhard; Bradford, Matt G; Cernusak, Lucas A; Cosio, Eric G; Creek, Danielle; Crous, Kristine Y; Domingues, Tomas F; Dukes, Jeffrey S; Egerton, John J G; Evans, John R; Farquhar, Graham D; Fyllas, Nikolaos M; Gauthier, Paul P G; Gloor, Emanuel; Gimeno, Teresa E; Griffin, Kevin L; Guerrieri, Rossella; Heskel, Mary A; Huntingford, Chris; Ishida, Françoise Yoko; Kattge, Jens; Lambers, Hans; Liddell, Michael J; Lloyd, Jon; Lusk, Christopher H; Martin, Roberta E; Maksimov, Ayal P; Maximov, Trofim C; Malhi, Yadvinder; Medlyn, Belinda E; Meir, Patrick; Mercado, Lina M; Mirotchnick, Nicholas; Ng, Desmond; Niinemets, Ülo; O'Sullivan, Odhran S; Phillips, Oliver L; Poorter, Lourens; Poot, Pieter; Prentice, I Colin; Salinas, Norma; Rowland, Lucy M; Ryan, Michael G; Sitch, Stephen; Slot, Martijn; Smith, Nicholas G; Turnbull, Matthew H; VanderWel, Mark C; Valladares, Fernando; Veneklaas, Erik J; Weerasinghe, Lasantha K; Wirth, Christian; Wright, Ian J; Wythers, Kirk R; Xiang, Jen; Xiang, Shuang; Zaragoza-Castells, Joana

    2015-04-01

    Leaf dark respiration (Rdark ) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits. Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark . Area-based Rdark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8-28°C). By contrast, Rdark at a standard T (25°C, Rdark (25) ) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark (25) at a given photosynthetic capacity (Vcmax (25) ) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark (25) values at any given Vcmax (25) or [N] were higher in herbs than in woody plants. The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs). © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  15. Improving respiration measurements with gas exchange analyzers.

    Science.gov (United States)

    Montero, R; Ribas-Carbó, M; Del Saz, N F; El Aou-Ouad, H; Berry, J A; Flexas, J; Bota, J

    2016-12-01

    Dark respiration measurements with open-flow gas exchange analyzers are often questioned for their low accuracy as their low values often reach the precision limit of the instrument. Respiration was measured in five species, two hypostomatous (Vitis Vinifera L. and Acanthus mollis) and three amphistomatous, one with similar amount of stomata in both sides (Eucalyptus citriodora) and two with different stomata density (Brassica oleracea and Vicia faba). CO 2 differential (ΔCO 2 ) increased two-fold with no change in apparent R d , when the two leaves with higher stomatal density faced outside. These results showed a clear effect of the position of stomata on ΔCO 2 . Therefore, it can be concluded that leaf position is important to guarantee the improvement of respiration measurements increasing ΔCO 2 without affecting the respiration results by leaf or mass units. This method will help to increase the accuracy of leaf respiration measurements using gas exchange analyzers. Copyright © 2016 Elsevier GmbH. All rights reserved.

  16. Effects of Soil Fertility and Atmospheric CO2 Enrichment on Leaf,Stem and Root Dark Respiration of Populus tremuloides

    Institute of Scientific and Technical Information of China (English)

    X.Z.WANG; P.S.CURTIS; 等

    2001-01-01

    An open-top chamber experiment was conducted at the University of Michigan Biological Station near Pellston,Michigan,USA,to study the effects of soil fertility and CO2 on leaf,sdtem and root dark respiration (Rd) of Populus tremuloides.Overall,area-based daytime leaf Rd(Rda) was significantly greater at elevated than at ambient CO2 in high-fertility soil,but not in low-fertility soil.Mass-based leaf Rd(Rdm) was overall greater for high-than for low-fertility soil grown trees at elevated,but not at ambient CO2 .Nighttime leaf Rda and Rdm were unaffected by soil fertility or CO2,nor was stem Rda ,which ranged from 1.0 to 1.4μmol m-2s-1 in the spring and 3.5 to 4.5μmol m-2s-1 in the summer.Root Rda was significantly higher in high-than in low-fertiliy soil,but was unaffected by CO2.Since biomass production of P.tremuloides will be significantly greater at elevated CO2 while specific Rd will either increase or remain unchanged,we predict that carbon loss to the atmosphere through respiration from this ecologically important species would increase at higher CO2.Soil fertility would also interact with elevated CO2 in affecting the carbon flow in the plant-soil-air system.

  17. Effects of Soil Fertility and Atmospheric CO2 Enrichment on Leaf, Stem and Root Dark Respiration of Populus tremuloides

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An open-top chamber experiment was conducted at the University of Michigan Biological Station near Pellston, Michigan, USA, to study the effects of soil fertility and CO2 on leaf, stem and root dark respiration (Rd) of Populus tremuloides. Overall, area-based daytime leaf Rd (Rda) was significantly greater at elevated than at ambient CO2 in high-fertility soil, but not in low-fertility soil. Mass-based leaf Rd (Rdm) was overall greater for high- than for low-fertility soil grown trees at elevated, but not at ambient CO2. Nighttime leaf Rda and Rdm were unaffected by soil fertility or CO2, nor was stem Rda, which ranged from 1.0 to 1.4 μmol m-2 s-1 in the spring and 3.5 to 4.5 μmol m-2 s-1 in the summer. Root Rda was significantly higher in high- than in low-fertility soil, but was unaffected by CO2. Since biomass production of P. tremuloides will be significantly greater at elevated CO2 while specific Rd will either increase or remain unchanged, we predict that carbon loss to the atmosphere through respiration from this ecologically important species would increase at higher CO2. Soil fertility would also interact with elevated CO2 in affecting the carbon flow in the plant-soil-air system.

  18. Effect of environmental variables and stand structure on ecosystem respiration components in a Mediterranean beech forest

    Czech Academy of Sciences Publication Activity Database

    Guidolotti, G.; Rey, A.; D'Andrea, E.; Matteucci, G.; De Angelis, Paolo

    2013-01-01

    Roč. 33, č. 9 (2013), s. 960-972 ISSN 0829-318X Institutional support: RVO:67179843 Keywords : ecosystem respiration * Fagus sylvatica * leaf respiration * soil CO2 efflux * stem CO2 efflux * total non-structural carbohydrates Subject RIV: EH - Ecology, Behaviour Impact factor: 3.405, year: 2013

  19. Boreal and temperate trees show strong acclimation of respiration to warming.

    Science.gov (United States)

    Reich, Peter B; Sendall, Kerrie M; Stefanski, Artur; Wei, Xiaorong; Rich, Roy L; Montgomery, Rebecca A

    2016-03-31

    Plant respiration results in an annual flux of carbon dioxide (CO2) to the atmosphere that is six times as large as that due to the emissions from fossil fuel burning, so changes in either will impact future climate. As plant respiration responds positively to temperature, a warming world may result in additional respiratory CO2 release, and hence further atmospheric warming. Plant respiration can acclimate to altered temperatures, however, weakening the positive feedback of plant respiration to rising global air temperature, but a lack of evidence on long-term (weeks to years) acclimation to climate warming in field settings currently hinders realistic predictions of respiratory release of CO2 under future climatic conditions. Here we demonstrate strong acclimation of leaf respiration to both experimental warming and seasonal temperature variation for juveniles of ten North American tree species growing for several years in forest conditions. Plants grown and measured at 3.4 °C above ambient temperature increased leaf respiration by an average of 5% compared to plants grown and measured at ambient temperature; without acclimation, these increases would have been 23%. Thus, acclimation eliminated 80% of the expected increase in leaf respiration of non-acclimated plants. Acclimation of leaf respiration per degree temperature change was similar for experimental warming and seasonal temperature variation. Moreover, the observed increase in leaf respiration per degree increase in temperature was less than half as large as the average reported for previous studies, which were conducted largely over shorter time scales in laboratory settings. If such dampening effects of leaf thermal acclimation occur generally, the increase in respiration rates of terrestrial plants in response to climate warming may be less than predicted, and thus may not raise atmospheric CO2 concentrations as much as anticipated.

  20. From leaf to whole-plant water use efficiency (WUE in complex canopies: Limitations of leaf WUE as a selection target

    Directory of Open Access Journals (Sweden)

    Hipólito Medrano

    2015-06-01

    Full Text Available Plant water use efficiency (WUE is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental sustainability of food production in these areas. Given that climate change predictions include increases in temperature and drought in semiarid regions, improving crop WUE is mandatory for global food production. WUE is commonly measured at the leaf level, because portable equipment for measuring leaf gas exchange rates facilitates the simultaneous measurement of photosynthesis and transpiration. However, when those measurements are compared with daily integrals or whole-plant estimates of WUE, the two sometimes do not agree. Scaling up from single-leaf to whole-plant WUE was tested in grapevines in different experiments by comparison of daily integrals of instantaneous water use efficiency [ratio between CO2 assimilation (AN and transpiration (E; AN/E] with midday AN/E measurements, showing a low correlation, being worse with increasing water stress. We sought to evaluate the importance of spatial and temporal variation in carbon and water balances at the leaf and plant levels. The leaf position (governing average light interception in the canopy showed a marked effect on instantaneous and daily integrals of leaf WUE. Night transpiration and respiration rates were also evaluated, as well as respiration contributions to total carbon balance. Two main components were identified as filling the gap between leaf and whole plant WUE: the large effect of leaf position on daily carbon gain and water loss and the large flux of carbon losses by dark respiration. These results show that WUE evaluation among genotypes or treatments needs to be revised.

  1. Seasonal and inter-annual variations of leaf-level photosynthesis and soil respiration in the representative ecosystems of the Okavango Delta, Botswana

    NARCIS (Netherlands)

    Mantlana, K.B.

    2008-01-01

    Seasonal and inter-annual leaf-level photosynthesis and soil respiration measurements were conducted in representative ecosystems of the Okavango Delta, Botswana, that differ in their long-term soil water content: the permanent swamp, the seasonal floodplain, the rain-fed grassland and the mopane

  2. Seasonality of temperate forest photosynthesis and daytime respiration.

    Science.gov (United States)

    Wehr, R; Munger, J W; McManus, J B; Nelson, D D; Zahniser, M S; Davidson, E A; Wofsy, S C; Saleska, S R

    2016-06-30

    Terrestrial ecosystems currently offset one-quarter of anthropogenic carbon dioxide (CO2) emissions because of a slight imbalance between global terrestrial photosynthesis and respiration. Understanding what controls these two biological fluxes is therefore crucial to predicting climate change. Yet there is no way of directly measuring the photosynthesis or daytime respiration of a whole ecosystem of interacting organisms; instead, these fluxes are generally inferred from measurements of net ecosystem-atmosphere CO2 exchange (NEE), in a way that is based on assumed ecosystem-scale responses to the environment. The consequent view of temperate deciduous forests (an important CO2 sink) is that, first, ecosystem respiration is greater during the day than at night; and second, ecosystem photosynthetic light-use efficiency peaks after leaf expansion in spring and then declines, presumably because of leaf ageing or water stress. This view has underlain the development of terrestrial biosphere models used in climate prediction and of remote sensing indices of global biosphere productivity. Here, we use new isotopic instrumentation to determine ecosystem photosynthesis and daytime respiration in a temperate deciduous forest over a three-year period. We find that ecosystem respiration is lower during the day than at night-the first robust evidence of the inhibition of leaf respiration by light at the ecosystem scale. Because they do not capture this effect, standard approaches overestimate ecosystem photosynthesis and daytime respiration in the first half of the growing season at our site, and inaccurately portray ecosystem photosynthetic light-use efficiency. These findings revise our understanding of forest-atmosphere carbon exchange, and provide a basis for investigating how leaf-level physiological dynamics manifest at the canopy scale in other ecosystems.

  3. Comparison of dwarf bamboos (Indocalamus sp.) leaf parameters to determine relationship between spatial density of plants and total leaf area per plant.

    Science.gov (United States)

    Shi, Pei-Jian; Xu, Qiang; Sandhu, Hardev S; Gielis, Johan; Ding, Yu-Long; Li, Hua-Rong; Dong, Xiao-Bo

    2015-10-01

    The relationship between spatial density and size of plants is an important topic in plant ecology. The self-thinning rule suggests a -3/2 power between average biomass and density or a -1/2 power between stand yield and density. However, the self-thinning rule based on total leaf area per plant and density of plants has been neglected presumably because of the lack of a method that can accurately estimate the total leaf area per plant. We aimed to find the relationship between spatial density of plants and total leaf area per plant. We also attempted to provide a novel model for accurately describing the leaf shape of bamboos. We proposed a simplified Gielis equation with only two parameters to describe the leaf shape of bamboos one model parameter represented the overall ratio of leaf width to leaf length. Using this method, we compared some leaf parameters (leaf shape, number of leaves per plant, ratio of total leaf weight to aboveground weight per plant, and total leaf area per plant) of four bamboo species of genus Indocalamus Nakai (I. pedalis (Keng) P.C. Keng, I. pumilus Q.H. Dai and C.F. Keng, I. barbatus McClure, and I. victorialis P.C. Keng). We also explored the possible correlation between spatial density and total leaf area per plant using log-linear regression. We found that the simplified Gielis equation fit the leaf shape of four bamboo species very well. Although all these four species belonged to the same genus, there were still significant differences in leaf shape. Significant differences also existed in leaf area per plant, ratio of leaf weight to aboveground weight per plant, and leaf length. In addition, we found that the total leaf area per plant decreased with increased spatial density. Therefore, we directly demonstrated the self-thinning rule to improve light interception.

  4. Exaggerated root respiration accounts for growth retardation in a starchless mutant of Arabidopsis thaliana.

    Science.gov (United States)

    Brauner, Katrin; Hörmiller, Imke; Nägele, Thomas; Heyer, Arnd G

    2014-07-01

    The knock-out mutation of plastidial phosphoglucomutase (pgm) causes a starchless phenotype in Arabidopsis thaliana, and results in a severe growth reduction of plants cultivated under diurnal conditions. It has been speculated that high soluble sugar levels accumulating during the light phase in leaf mesophyll might cause a reduction of photosynthetic activity or that shortage of reduced carbon during the night is the reason for the slow biomass gain of pgm. Separate simultaneous measurements of leaf net photosynthesis and root respiration demonstrate that photosynthetic activity per unit fresh weight is not reduced in pgm, whereas root respiration is strongly elevated. Comparison with a mutant defective in the dominating vacuolar invertase (AtβFruct4) revealed that high sucrose concentration in the cytosol, but not in the vacuole, of leaf cells is responsible for elevated assimilate transport to the root. Increased sugar supply to the root, as observed in pgm mutants, forces substantial respiratory losses. Because root respiration accounts for 80% of total plant respiration under long-day conditions, this gives rise to retarded biomass formation. In contrast, reduced vacuolar invertase activity leads to reduced net photosynthesis in the shoot and lowered root respiration, and affords an increased root/shoot ratio. The results demonstrate that roots have very limited capacity for carbon storage but exert rigid control of supply for their maintenance metabolism. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

  5. Nutrients and temperature additively increase stream microbial respiration

    Science.gov (United States)

    David W. P. Manning; Amy D. Rosemond; Vladislav Gulis; Jonathan P. Benstead; John S. Kominoski

    2017-01-01

    Rising temperatures and nutrient enrichment are co‐occurring global‐change drivers that stimulate microbial respiration of detrital carbon, but nutrient effects on the temperature dependence of respiration in aquatic ecosystems remain uncertain. We measured respiration rates associated with leaf litter, wood, and fine benthic organic matter (FBOM) across...

  6. Effects of elevated atmospheric CO2 concentration on leaf dark respiration of Xanthium strumarium in light and in darkness.

    Science.gov (United States)

    Wang, X; Lewis, J D; Tissue, D T; Seemann, J R; Griffin, K L

    2001-02-27

    Leaf dark respiration (R) is an important component of plant carbon balance, but the effects of rising atmospheric CO(2) on leaf R during illumination are largely unknown. We studied the effects of elevated CO(2) on leaf R in light (R(L)) and in darkness (R(D)) in Xanthium strumarium at different developmental stages. Leaf R(L) was estimated by using the Kok method, whereas leaf R(D) was measured as the rate of CO(2) efflux at zero light. Leaf R(L) and R(D) were significantly higher at elevated than at ambient CO(2) throughout the growing period. Elevated CO(2) increased the ratio of leaf R(L) to net photosynthesis at saturated light (A(max)) when plants were young and also after flowering, but the ratio of leaf R(D) to A(max) was unaffected by CO(2) levels. Leaf R(N) was significantly higher at the beginning but significantly lower at the end of the growing period in elevated CO(2)-grown plants. The ratio of leaf R(L) to R(D) was used to estimate the effect of light on leaf R during the day. We found that light inhibited leaf R at both CO(2) concentrations but to a lesser degree for elevated (17-24%) than for ambient (29-35%) CO(2)-grown plants, presumably because elevated CO(2)-grown plants had a higher demand for energy and carbon skeletons than ambient CO(2)-grown plants in light. Our results suggest that using the CO(2) efflux rate, determined by shading leaves during the day, as a measure for leaf R is likely to underestimate carbon loss from elevated CO(2)-grown plants.

  7. Carbohydrate regulation of photosynthesis and respiration from branch girdling in four species of wet tropical rain forest trees.

    Science.gov (United States)

    Asao, Shinichi; Ryan, Michael G

    2015-06-01

    How trees sense source-sink carbon balance remains unclear. One potential mechanism is a feedback from non-structural carbohydrates regulating photosynthesis and removing excess as waste respiration when the balance of photosynthesis against growth and metabolic activity changes. We tested this carbohydrate regulation of photosynthesis and respiration using branch girdling in four tree species in a wet tropical rainforest in Costa Rica. Because girdling severs phloem to stop carbohydrate export while leaving xylem intact to allow photosynthesis, we expected carbohydrates to accumulate in leaves to simulate a carbon imbalance. We varied girdling intensity by removing phloem in increments of one-quarter of the circumference (zero, one--quarter, half, three-quarters, full) and surrounded a target branch with fully girdled ones to create a gradient in leaf carbohydrate content. Light saturated photosynthesis rate was measured in situ, and foliar respiration rate and leaf carbohydrate content were measured after destructive harvest at the end of the treatment. Girdling intensity created no consistent or strong responses in leaf carbohydrates. Glucose and fructose slightly increased in all species by 3.4% per one-quarter girdle, total carbon content and leaf mass per area increased only in one species by 5.4 and 5.5% per one-quarter girdle, and starch did not change. Only full girdling lowered photosynthesis in three of four species by 59-69%, but the decrease in photosynthesis was unrelated to the increase in glucose and fructose content. Girdling did not affect respiration. The results suggest that leaf carbohydrate content remains relatively constant under carbon imbalance, and any changes are unlikely to regulate photosynthesis or respiration. Because girdling also stops the export of hormones and reactive oxygen species, girdling may induce physiological changes unrelated to carbohydrate accumulation and may not be an effective method to study carbohydrate feedback

  8. Evaluating a new method to estimate the rate of leaf respiration in the light by analysis of combined gas exchange and chlorophyll fluorescence measurements

    NARCIS (Netherlands)

    Yin, X.; Sun, Z.; Struik, P.C.; Gu, J.

    2011-01-01

    Day respiration (R(d)) is an important parameter in leaf ecophysiology. It is difficult to measure directly and is indirectly estimated from gas exchange (GE) measurements of the net photosynthetic rate (A), commonly using the Laisk method or the Kok method. Recently a new method was proposed to

  9. Leaf litter is an important mediator of soil respiration in an oak-dominated forest

    Science.gov (United States)

    Jared L. DeForest; Jiquan Chen; Steve G. McNulty

    2009-01-01

    The contribution of the organic (O) horizon to total soil respiration is poorly understood even though it can represent a large source of uncertainty due to seasonal changes in microclimate and O horizon properties due to plant phenology. Our objectives were to partition the CO2 effluxes of litter layer and mineral soil from total soil...

  10. Macromolecular Rate Theory (MMRT) Provides a Thermodynamics Rationale to Underpin the Convergent Temperature Response in Plant Leaf Respiration

    Science.gov (United States)

    Liang, L. L.; Arcus, V. L.; Heskel, M.; O'Sullivan, O. S.; Weerasinghe, L. K.; Creek, D.; Egerton, J. J. G.; Tjoelker, M. G.; Atkin, O. K.; Schipper, L. A.

    2017-12-01

    Temperature is a crucial factor in determining the rates of ecosystem processes such as leaf respiration (R) - the flux of plant respired carbon dioxide (CO2) from leaves to the atmosphere. Generally, respiration rate increases exponentially with temperature as modelled by the Arrhenius equation, but a recent study (Heskel et al., 2016) showed a universally convergent temperature response of R using an empirical exponential/polynomial model whereby the exponent in the Arrhenius model is replaced by a quadratic function of temperature. The exponential/polynomial model has been used elsewhere to describe shoot respiration and plant respiration. What are the principles that underlie these empirical observations? Here, we demonstrate that macromolecular rate theory (MMRT), based on transition state theory for chemical kinetics, is equivalent to the exponential/polynomial model. We re-analyse the data from Heskel et al. 2016 using MMRT to show this equivalence and thus, provide an explanation based on thermodynamics, for the convergent temperature response of R. Using statistical tools, we also show the equivalent explanatory power of MMRT when compared to the exponential/polynomial model and the superiority of both of these models over the Arrhenius function. Three meaningful parameters emerge from MMRT analysis: the temperature at which the rate of respiration is maximum (the so called optimum temperature, Topt), the temperature at which the respiration rate is most sensitive to changes in temperature (the inflection temperature, Tinf) and the overall curvature of the log(rate) versus temperature plot (the so called change in heat capacity for the system, ). The latter term originates from the change in heat capacity between an enzyme-substrate complex and an enzyme transition state complex in enzyme-catalysed metabolic reactions. From MMRT, we find the average Topt and Tinf of R are 67.0±1.2 °C and 41.4±0.7 °C across global sites. The average curvature (average

  11. Total belowground carbon flux in subalpine forests is related to leaf area index, soil nitrogen, and tree height

    Science.gov (United States)

    Berryman, Erin Michele; Ryan, Michael G.; Bradford, John B.; Hawbaker, Todd J.; Birdsey, R.

    2016-01-01

    In forests, total belowground carbon (C) flux (TBCF) is a large component of the C budget and represents a critical pathway for delivery of plant C to soil. Reducing uncertainty around regional estimates of forest C cycling may be aided by incorporating knowledge of controls over soil respiration and TBCF. Photosynthesis, and presumably TBCF, declines with advancing tree size and age, and photosynthesis increases yet C partitioning to TBCF decreases in response to high soil fertility. We hypothesized that these causal relationships would result in predictable patterns of TBCF, and partitioning of C to TBCF, with natural variability in leaf area index (LAI), soil nitrogen (N), and tree height in subalpine forests in the Rocky Mountains, USA. Using three consecutive years of soil respiration data collected from 22 0.38-ha locations across three 1-km2 subalpine forested landscapes, we tested three hypotheses: (1) annual soil respiration and TBCF will show a hump-shaped relationship with LAI; (2) variability in TBCF unexplained by LAI will be related to soil nitrogen (N); and (3) partitioning of C to TBCF (relative to woody growth) will decline with increasing soil N and tree height. We found partial support for Hypothesis 1 and full support for Hypotheses 2 and 3. TBCF, but not soil respiration, was explained by LAI and soil N patterns (r2 = 0.49), and the ratio of annual TBCF to TBCF plus aboveground net primary productivity (ANPP) was related to soil N and tree height (r2 = 0.72). Thus, forest C partitioning to TBCF can vary even within the same forest type and region, and approaches that assume a constant fraction of TBCF relative to ANPP may be missing some of this variability. These relationships can aid with estimates of forest soil respiration and TBCF across landscapes, using spatially explicit forest data such as national inventories or remotely sensed data products.

  12. Plant Respiration and Climate Change Effects

    International Nuclear Information System (INIS)

    Bruhn, D.

    2002-04-01

    Plant respiration is one of the key processes in terms of an understanding of plant growth and functioning in a future climate. Short- and long-term effects of temperature and CO 2 on plant respiration were investigated in a number of plant species. The experiments tested effects of either temperature and/or CO 2 from the level of individual respiratory enzymes, isolated mitochondria, whole-tissue, and up to the whole canopy level. The short-term effects of elevated atmospheric CO 2 on plant respiration appeared to be less than suggested so far in the literature. This was true both at the tissue level and for intact mitochondria. Respiratory enzymes can, however, be affected already at low CO 2 . These effects did not manifest itself at the tissue level, though, due to low degrees of control on the whole respiratory process exerted by the particular enzymes. Plant respiration on the other hand was affected by long-term growth at elevated atmospheric CO 2 . The findings of the reduced plant respiration at the leaf level were consistent with the literature and potential causes are discussed. Short-term effects of temperature on plant respiration were demonstrated to be dependent on the actual measurement temperature. Further, it is shown that mitochondrial leaf respiration in darkness and light differ substantially in the temperature sensitivity with the former being the far most sensitive. This has implications for modelling CO 2 exchange between vegetation and atmosphere as demonstrated here, since this has so far been neglected. Long-term effects of temperature resulted in respiratory acclimation in a number of species. Respiratory acclimation appeared not to occur to any one single type of growth temperature. The implications of this finding in combination with the timing of acclimation are discussed for modelling respiratory CO 2 release. (au)

  13. Plant Respiration and Climate Change Effects

    Energy Technology Data Exchange (ETDEWEB)

    Bruhn, D

    2002-04-01

    Plant respiration is one of the key processes in terms of an understanding of plant growth and functioning in a future climate. Short- and long-term effects of temperature and CO{sub 2} on plant respiration were investigated in a number of plant species. The experiments tested effects of either temperature and/or CO{sub 2} from the level of individual respiratory enzymes, isolated mitochondria, whole-tissue, and up to the whole canopy level. The short-term effects of elevated atmospheric CO{sub 2} on plant respiration appeared to be less than suggested so far in the literature. This was true both at the tissue level and for intact mitochondria. Respiratory enzymes can, however, be affected already at low CO{sub 2}. These effects did not manifest itself at the tissue level, though, due to low degrees of control on the whole respiratory process exerted by the particular enzymes. Plant respiration on the other hand was affected by long-term growth at elevated atmospheric CO{sub 2}. The findings of the reduced plant respiration at the leaf level were consistent with the literature and potential causes are discussed. Short-term effects of temperature on plant respiration were demonstrated to be dependent on the actual measurement temperature. Further, it is shown that mitochondrial leaf respiration in darkness and light differ substantially in the temperature sensitivity with the former being the far most sensitive. This has implications for modelling CO{sub 2} exchange between vegetation and atmosphere as demonstrated here, since this has so far been neglected. Long-term effects of temperature resulted in respiratory acclimation in a number of species. Respiratory acclimation appeared not to occur to any one single type of growth temperature. The implications of this finding in combination with the timing of acclimation are discussed for modelling respiratory CO{sub 2} release. (au)

  14. Foliar and ecosystem respiration in an old-growth tropical rain forest

    Science.gov (United States)

    Molly A. Cavaleri; Steven F. Oberbauer; Michael G. Ryan

    2008-01-01

    Foliar respiration is a major component of ecosystem respiration, yet extrapolations are often uncertain in tropical forests because of indirect estimates of leaf area index (LAI).A portable tower was used to directly measure LAI and night-time foliar respiration from 52 vertical transects throughout an old-growth tropical rain forest in Costa Rica. In this study, we (...

  15. Variation in foliar respiration and wood CO2 efflux rates among species and canopy layers in a wet tropical forest.

    Science.gov (United States)

    Asao, Shinichi; Bedoya-Arrieta, Ricardo; Ryan, Michael G

    2015-02-01

    As tropical forests respond to environmental change, autotrophic respiration may consume a greater proportion of carbon fixed in photosynthesis at the expense of growth, potentially turning the forests into a carbon source. Predicting such a response requires that we measure and place autotrophic respiration in a complete carbon budget, but extrapolating measurements of autotrophic respiration from chambers to ecosystem remains a challenge. High plant species diversity and complex canopy structure may cause respiration rates to vary and measurements that do not account for this complexity may introduce bias in extrapolation more detrimental than uncertainty. Using experimental plantations of four native tree species with two canopy layers, we examined whether species and canopy layers vary in foliar respiration and wood CO2 efflux and whether the variation relates to commonly used scalars of mass, nitrogen (N), photosynthetic capacity and wood size. Foliar respiration rate varied threefold between canopy layers, ∼0.74 μmol m(-2) s(-1) in the overstory and ∼0.25 μmol m(-2) s(-1) in the understory, but little among species. Leaf mass per area, N and photosynthetic capacity explained some of the variation, but height explained more. Chamber measurements of foliar respiration thus can be extrapolated to the canopy with rates and leaf area specific to each canopy layer or height class. If area-based rates are sampled across canopy layers, the area-based rate may be regressed against leaf mass per area to derive the slope (per mass rate) to extrapolate to the canopy using the total leaf mass. Wood CO2 efflux varied 1.0-1.6 μmol m(-2) s(-1) for overstory trees and 0.6-0.9 μmol m(-2) s(-1) for understory species. The variation in wood CO2 efflux rate was mostly related to wood size, and little to species, canopy layer or height. Mean wood CO2 efflux rate per surface area, derived by regressing CO2 efflux per mass against the ratio of surface

  16. Effects of exercise and respiration on blood flow in total cavopulmonary connection

    DEFF Research Database (Denmark)

    Hjortdal, V E; Emmertsen, K; Stenbøg, E

    2003-01-01

    BACKGROUND: Little is known about blood flow and its relationship to respiration during exercise in patients with total cavopulmonary connection (TCPC). METHODS AND RESULTS: We studied 11 patients 12.4+/-4.6 years (mean+/-SD) of age 5.9+/-2.8 years (mean+/-SD) after TCPC operation. Real-time MRI...

  17. The diel imprint of leaf metabolism on the δ13 C signal of soil respiration under control and drought conditions.

    Science.gov (United States)

    Barthel, Matthias; Hammerle, Albin; Sturm, Patrick; Baur, Thomas; Gentsch, Lydia; Knohl, Alexander

    2011-12-01

    Recent (13) CO(2) canopy pulse chase labeling studies revealed that photosynthesis influences the carbon isotopic composition of soil respired CO(2) (δ(13) C(SR)) even on a diel timescale. However, the driving mechanisms underlying these short-term responses remain unclear, in particular under drought conditions. The gas exchange of CO(2) isotopes of canopy and soil was monitored in drought/nondrought-stressed beech (Fagus sylvatica) saplings after (13) CO(2) canopy pulse labeling. A combined canopy/soil chamber system with gas-tight separated soil and canopy compartments was coupled to a laser spectrometer measuring mixing ratios and isotopic composition of CO(2) in air at high temporal resolution. The measured δ(13) C(SR) signal was then explained and substantiated by a mechanistic carbon allocation model. Leaf metabolism had a strong imprint on diel cycles in control plants, as a result of an alternating substrate supply switching between sugar and transient starch. By contrast, diel cycles in drought-stressed plants were determined by the relative contributions of autotrophic and heterotrophic respiration throughout the day. Drought reduced the speed of the link between photosynthesis and soil respiration by a factor of c. 2.5, depending on the photosynthetic rate. Drought slows the coupling between photosynthesis and soil respiration and alters the underlying mechanism causing diel variations of δ(13) C(SR). © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

  18. Estimating daytime ecosystem respiration from eddy-flux data

    DEFF Research Database (Denmark)

    Bruhn, Dan; Mikkelsen, Teis Nørgaard; Herbst, Mathias

    2011-01-01

    To understand what governs the patterns of net ecosystem exchange of CO2, an understanding of factors influencing the component fluxes, ecosystem respiration and gross primary production is needed. In the present paper, we introduce an alternative method for estimating daytime ecosystem respiration...... based on whole ecosystem fluxes from a linear regression of photosynthetic photon flux density data vs. daytime net ecosystem exchange data at forest ecosystem level. This method is based on the principles of the Kok-method applied at leaf level for estimating daytime respiration. We demonstrate...

  19. Estimating the total leaf area of the green dwarf coconut tree (Cocos nucifera L.

    Directory of Open Access Journals (Sweden)

    Sousa Elias Fernandes de

    2005-01-01

    Full Text Available Leaf area has significant effect on tree transpiration, and its measurement is important to many study areas. This work aimed at developing a non-destructive, practical, and empirical method to estimate the total leaf area of green dwarf coconut palms (Cocos nucifera L. in plantations located at the northern region of Rio de Janeiro state, Brazil. A mathematical model was developed to estimate total leaf area values (TLA as function of the average lengths of the last three leaf raquis (LR3, and of the number of leaves in the canopy (NL. The model has satisfactory degree of accuracy for agricultural engineering purposes.

  20. Quantifying Components of Soil Respiration and Their Response to Abiotic Factors in Two Typical Subtropical Forest Stands, Southwest China

    Science.gov (United States)

    Yu, Lei; Wang, Yujie; Wang, Yunqi; Sun, Suqi; Liu, Liziyuan

    2015-01-01

    Separating the components of soil respiration and understanding the roles of abiotic factors at a temporal scale among different forest types are critical issues in forest ecosystem carbon cycling. This study quantified the proportions of autotrophic (R A) and heterotrophic (R H) in total soil (R T) respiration using trenching and litter removal. Field studies were conducted in two typical subtropical forest stands (broadleaf and needle leaf mixed forest; bamboo forest) at Jinyun Mountain, near the Three Georges Reservoir in southwest China, during the growing season (Apr.–Sep.) from 2010 to 2012. The effects of air temperature (AT), soil temperature (ST) and soil moisture (SM) at 6cm depth, solar radiation (SR), pH on components of soil respiration were analyzed. Results show that: 1) SR, AT, and ST exhibited a similar temporal trend. The observed abiotic factors showed slight interannual variability for the two forest stands. 2) The contributions of R H and R A to R T for broadleaf and needle leaf mixed forest were 73.25% and 26.75%, respectively, while those for bamboo forest were 89.02% and 10.98%, respectively; soil respiration peaked from June to July. In both stands, CO2 released from the decomposition of soil organic matter (SOM), the strongest contributor to R T, accounted for over 63% of R H. 3) AT and ST were significantly positively correlated with R T and its components (psoil respiration. 4) Components of soil respiration were significantly different between two forest stands (psoil respiration and its components. PMID:25680112

  1. Modeling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices

    Science.gov (United States)

    Reichstein, Markus; Rey, Ana; Freibauer, Annette; Tenhunen, John; Valentini, Riccardo; Banza, Joao; Casals, Pere; Cheng, Yufu; Grünzweig, Jose M.; Irvine, James; Joffre, Richard; Law, Beverly E.; Loustau, Denis; Miglietta, Franco; Oechel, Walter; Ourcival, Jean-Marc; Pereira, Joao S.; Peressotti, Alessandro; Ponti, Francesca; Qi, Ye; Rambal, Serge; Rayment, Mark; Romanya, Joan; Rossi, Federica; Tedeschi, Vanessa; Tirone, Giampiero; Xu, Ming; Yakir, Dan

    2003-12-01

    Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, interannual and spatial variability of soil respiration as affected by water availability, temperature, and site properties. The analysis was performed at a daily and at a monthly time step. With the daily time step, the relative soil water content in the upper soil layer expressed as a fraction of field capacity was a good predictor of soil respiration at all sites. Among the site variables tested, those related to site productivity (e.g., leaf area index) correlated significantly with soil respiration, while carbon pool variables like standing biomass or the litter and soil carbon stocks did not show a clear relationship with soil respiration. Furthermore, it was evidenced that the effect of precipitation on soil respiration stretched beyond its direct effect via soil moisture. A general statistical nonlinear regression model was developed to describe soil respiration as dependent on soil temperature, soil water content, and site-specific maximum leaf area index. The model explained nearly two thirds of the temporal and intersite variability of soil respiration with a mean absolute error of 0.82 μmol m-2 s-1. The parameterized model exhibits the following principal properties: (1) At a relative amount of upper-layer soil water of 16% of field capacity, half-maximal soil respiration rates are reached. (2) The apparent temperature sensitivity of soil respiration measured as Q10 varies between 1 and 5 depending on soil temperature and water content. (3) Soil respiration under reference moisture and temperature conditions is linearly related to maximum site leaf area index. At a monthly timescale, we employed the approach by [2002] that used monthly precipitation and air temperature to globally predict soil respiration (T&P model). While this model was able to

  2. Modelling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices

    Science.gov (United States)

    Reichstein, M.; Rey, A.; Freibauer, A.; Tenhunen, J.; Valentini, R.; Soil Respiration Synthesis Team

    2003-04-01

    Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, inter-annual and spatial variability of soil respiration as affected by water availability, temperature and site properties. The analysis was performed at a daily and at a monthly time step. With the daily time step, the relative soil water content in the upper soil layer expressed as a fraction of field capacity was a good predictor of soil respiration at all sites. Among the site variables tested, those related to site productivity (e.g. leaf area index) correlated significantly with soil respiration, while carbon pool variables like standing biomass or the litter and soil carbon stocks did not show a clear relationship with soil respiration. Furthermore, it was evidenced that the effect of precipitation on soil respiration stretched beyond its direct effect via soil moisture. A general statistical non-linear regression model was developed to describe soil respiration as dependent on soil temperature, soil water content and site-specific maximum leaf area index. The model explained nearly two thirds of the temporal and inter-site variability of soil respiration with a mean absolute error of 0.82 µmol m-2 s-1. The parameterised model exhibits the following principal properties: 1) At a relative amount of upper-layer soil water of 16% of field capacity half-maximal soil respiration rates are reached. 2) The apparent temperature sensitivity of soil respiration measured as Q10 varies between 1 and 5 depending on soil temperature and water content. 3) Soil respiration under reference moisture and temperature conditions is linearly related to maximum site leaf area index. At a monthly time-scale we employed the approach by Raich et al. (2002, Global Change Biol. 8, 800-812) that used monthly precipitation and air temperature to globally predict soil respiration (T

  3. Drought Sensitivity of the Carbon Isotope Composition of Leaf Dark-Respired CO2 in C3 (Leymus chinensis) and C4 (Chloris virgata and Hemarthria altissima) Grasses in Northeast China

    OpenAIRE

    Zhong, Shangzhi; Chai, Hua; Xu, Yueqiao; Li, Yan; Ma, Jian-Ying; Sun, Wei

    2017-01-01

    Whether photosynthetic pathway differences exist in the amplitude of nighttime variations in the carbon isotope composition of leaf dark-respired CO2 (δ13Cl) and respiratory apparent isotope fractionation relative to biomass (ΔR,biomass) in response to drought stress is unclear. These differences, if present, would be important for the partitioning of C3-C4 mixed ecosystem C fluxes. We measured δ13Cl, the δ13C of biomass and of potential respiratory substrates and leaf gas exchange in one C3 ...

  4. Contribution of Root Respiration to Soil Respiration in Sugarcane Plantation in Thailand

    OpenAIRE

    Wilaiwan Sornpoon; Sebastien Bonnet; Poonpipope Kasemsap; Savitri Garivait

    2013-01-01

    The understanding on the contribution of root respiration to total soil respiration is still very limited, especially for sugarcane. In this study, trenching experiments in sugarcane plantations were conducted to separate and investigate soil respiration for this crop. The measurements were performed for the whole growing period of 344 days to quantify root respiration. The obtained monitoring data showed that the respiration rate is increasing with the age of the plant, accounting for up to ...

  5. Soil respiration fluxes in a temperate mixed forest: seasonality and temperature sensitivities differ among microbial and root-rhizosphere respiration.

    Science.gov (United States)

    Ruehr, Nadine K; Buchmann, Nina

    2010-02-01

    Although soil respiration, a major CO(2) flux in terrestrial ecosystems, is known to be highly variable with time, the response of its component fluxes to temperature and phenology is less clear. Therefore, we partitioned soil respiration (SR) into microbial (MR) and root-rhizosphere respiration (RR) using small root exclusion treatments in a mixed mountain forest in Switzerland. In addition, fine root respiration (FRR) was determined with measurements of excised roots. RR and FRR were strongly related to each other (R(2) = 0.92, n = 7), with RR contributing about 46% and FRR about 32% to total SR. RR rates increased more strongly with temperature (Q(10) = 3.2) than MR rates (Q(10) = 2.3). Since the contribution of RR to SR was found to be higher during growing (50%) than during dormant periods (40%), we separated the 2-year data set into phenophases. During the growing period of 2007, the temperature sensitivity of RR (Q(10) = 2.5, R(2) = 0.62) was similar to that of MR (Q(10) = 2.2, R(2) = 0.57). However, during the dormant period of 2006/2007, RR was not related to soil temperature (R(2) = 0.44, n.s.), in contrast to MR (Q(10) = 7.2; R(2) = 0.92). To better understand the influence of plant activity on root respiration, we related RR and FRR rates to photosynthetic active radiation (both R(2) = 0.67, n = 7, P = 0.025), suggesting increased root respiration rates during times with high photosynthesis. During foliage green-up in spring 2008, i.e., from bud break to full leaf expansion, RR increased by a factor of 5, while soil temperature increased only by about 5 degrees C, leading to an extraordinary high Q(10) of 10.6; meanwhile, the contribution of RR to SR increased from 29 to 47%. This clearly shows that root respiration and its apparent temperature sensitivity highly depend on plant phenology and thus on canopy assimilation and carbon allocation belowground.

  6. A distinct seasonal pattern of the ratio of soil respiration to total ecosystem respiration in a spruce-dominated forest

    Science.gov (United States)

    E.A. Davidson; A.D. Richardson; K.E. Savage; D.Y. Hollinger

    2006-01-01

    Annual budgets and fitted temperature response curves for soil respiration and ecosystem respiration provide useful information for partitioning annual carbon budgets of ecosystems, but they may not adequately reveal seasonal variation in the ratios of these two fluxes. Soil respiration (Rs) typically contributes 30-80% of...

  7. Response of Respiration of Soybean Leaves Grown at Ambient and Elevated Carbon Dioxide Concentrations to Day-to-day Variation in Light and Temperature under Field Conditions

    Science.gov (United States)

    BUNCE, JAMES A.

    2005-01-01

    • Background and Aims Respiration is an important component of plant carbon balance, but it remains uncertain how respiration will respond to increases in atmospheric carbon dioxide concentration, and there are few measurements of respiration for crop plants grown at elevated [CO2] under field conditions. The hypothesis that respiration of leaves of soybeans grown at elevated [CO2] is increased is tested; and the effects of photosynthesis and acclimation to temperature examined. • Methods Net rates of carbon dioxide exchange were recorded every 10 min, 24 h per day for mature upper canopy leaves of soybeans grown in field plots at the current ambient [CO2] and at ambient plus 350 µmol mol−1 [CO2] in open top chambers. Measurements were made on pairs of leaves from both [CO2] treatments on a total of 16 d during the middle of the growing seasons of two years. • Key Results Elevated [CO2] increased daytime net carbon dioxide fixation rates per unit of leaf area by an average of 48 %, but had no effect on night-time respiration expressed per unit of area, which averaged 53 mmol m−2 d−1 (1·4 µmol m−2 s−1) for both the ambient and elevated [CO2] treatments. Leaf dry mass per unit of area was increased on average by 23 % by elevated [CO2], and respiration per unit of mass was significantly lower at elevated [CO2]. Respiration increased by a factor of 2·5 between 18 and 26 °C average night temperature, for both [CO2] treatments. • Conclusions These results do not support predictions that elevated [CO2] would increase respiration per unit of area by increasing photosynthesis or by increasing leaf mass per unit of area, nor the idea that acclimation of respiration to temperature would be rapid enough to make dark respiration insensitive to variation in temperature between nights. PMID:15781437

  8. Changes in δ(13)C of dark respired CO2 and organic matter of different organs during early ontogeny in peanut plants.

    Science.gov (United States)

    Ghashghaie, Jaleh; Badeck, Franz W; Girardin, Cyril; Sketriené, Diana; Lamothe-Sibold, Marlène; Werner, Roland A

    2015-01-01

    Carbon isotope composition in respired CO2 and organic matter of individual organs were measured on peanut seedlings during early ontogeny in order to compare fractionation during heterotrophic growth and transition to autotrophy in a species with lipid seed reserves with earlier results obtained on beans. Despite a high lipid content in peanut seeds (48%) compared with bean seeds (1.5%), the isotope composition of leaf- and root-respired CO2 as well as its changes during ontogeny were similar to already published data on bean seedlings: leaf-respired CO2 became (13)C-enriched reaching -21.5‰, while root-respired CO2 became (13)C-depleted reaching around -31‰ at the four-leaf stage. The opposite respiratory fractionation in leaves vs. roots already reported for C3 herbs was thus confirmed for peanuts. However, contrarily to beans, the peanut cotyledon-respired CO2 was markedly (13)C-enriched, and its (13)C-depletion was noted from the two-leaf stage onwards only. Carbohydrate amounts being very low in peanut seeds, this cannot be attributed solely to their use as respiratory substrate. The potential role of isotope fractionation during glyoxylate cycle and/or gluconeogenesis on the (13)C-enriched cotyledon-respired CO2 is discussed.

  9. Effect of weed control treatments on total leaf area of plantation black walnut (Juglans nigra)

    Science.gov (United States)

    Jason Cook; Michael R. Saunders

    2013-01-01

    Determining total tree leaf area is necessary for describing tree carbon balance, growth efficiency, and other measures used in tree-level and stand-level physiological growth models. We examined the effects of vegetation control methods on the total leaf area of sapling-size plantation black walnut trees using allometric approaches. We found significant differences in...

  10. Impact of needle age on the response of respiration in Scots pine to long-term elevation of carbon dioxide concentration and temperature

    International Nuclear Information System (INIS)

    Zha, T.; Ryyppo, A.; Kellomaki, S.; Wang, K-Y.

    2002-01-01

    The effects of needle age, elevated carbon dioxide and temperature on needle respiration in Scots pine was studied during a four-year period. Results showed that respiration rates and specific leaf area decreased in elevated atmospheric carbon dioxide concentration relative to ambient conditions, but increased in elevated temperature and when elevated atmospheric carbon dioxide and elevated temperature were combined. Starch and soluble sugar concentrations for a given needle age increased in elevated carbon dioxide, but decreased slightly under combined elevated temperature and elevated carbon dioxide conditions. Respiration rate and specific leaf area were highest in current year needles in all treatment modes. All treatment modes enhanced the difference in respiration between current year and older needles relative to ambient conditions. Carbohydrate concentration or specific leaf area remained unchanged in response to any treatment. Under ambient conditions the temperature coefficient of respiration increased slightly in elevated carbon dioxide regardless of age, however, there was significant decline at elevated temperature as well as when both carbon dioxide concentration and temperature were elevated, indicating acclimation of respiration to temperature. 48 refs., 2 tabs., 7 figs

  11. Total Lactic Acid Bacteria (LAB), Antioxidant Activity, and Acceptance of Synbiotic Yoghurt with Binahong Leaf Extract (Anredera cordifolia (Ten.) Steenis)

    Science.gov (United States)

    Lestari, R. P.; Nissa, C.; Afifah, D. N.; Anjani, G.; Rustanti, N.

    2018-02-01

    Alternative treatment for metabolic syndrome can be done by providing a diet consist of functional foods or beverages. Synbiotic yoghurt containing binahong leaf extract which high in antioxidant, total LAB and fiber can be selected to reduce the risk of metabolic syndrome. The effect of binahong leaf extract in synbiotic yoghurt against total LAB, antioxidant activity, and acceptance were analyzed. The experiment was done with complete randomized design with addition of binahong leaf extract 0% (control); 0.12%; 0.25%; 0.5% in synbiotic yoghurt. Analysis of total LAB using Total Plate Count test, antioxidant activity using DPPH, and acceptance were analyzed by hedonic test. The addition of binahong leaf extract in various doses in synbiotic yoghurt decreased total LAB without significant effect (p=0,145). There was no effect of addition binahong leaf extract on antioxidant activity (p=0,297). The addition of binahong leaf extract had an effect on color, but not on aroma, texture and taste. The best result was yoghurt synbiotic with addition of 0,12% binahong leaf extract. Conclusion of the research was the addition of binahong leaf extract to synbiotic yogurt did not significantly affect total LAB, antioxidant activity, aroma, texture and taste; but had a significant effect on color.

  12. Leaf Physiological and Morphological Responses to Shade in Grass-Stage Seedlings and Young Trees of Longleaf Pine

    Directory of Open Access Journals (Sweden)

    Lisa J. Samuelson

    2012-08-01

    Full Text Available Longleaf pine has been classified as very shade intolerant but leaf physiological plasticity to light is not well understood, especially given longleaf pine’s persistent seedling grass stage. We examined leaf morphological and physiological responses to light in one-year-old grass-stage seedlings and young trees ranging in height from 4.6 m to 6.3 m to test the hypothesis that young longleaf pine would demonstrate leaf phenotypic plasticity to light environment. Seedlings were grown in a greenhouse under ambient levels of photosynthetically active radiation (PAR or a 50% reduction in ambient PAR and whole branches of trees were shaded to provide a 50% reduction in ambient PAR. In seedlings, shading reduced leaf mass per unit area (LMA, the light compensation point, and leaf dark respiration (RD, and increased the ratio of light-saturated photosynthesis to RD and chlorophyll b and total chlorophyll expressed per unit leaf dry weight. In trees, shading reduced LMA, increased chlorophyll a, chlorophyll b and total chlorophyll on a leaf dry weight basis, and increased allocation of total foliar nitrogen to chlorophyll nitrogen. Changes in leaf morphological and physiological traits indicate a degree of shade tolerance that may have implications for even and uneven-aged management of longleaf pine.

  13. Species identities, not functional groups, explain the effects of earthworms on litter carbon-derived soil respiration

    Science.gov (United States)

    Soil respiration is frequently measured as a surrogate for biological activities and is important in soil carbon cycling. The heterotrophic component of soil respiration is primarily driven by microbial decomposition of leaf litter and soil organic matter, and is partially controlled by resource ava...

  14. Estimating Canopy Dark Respiration for Crop Models

    Science.gov (United States)

    Monje Mejia, Oscar Alberto

    2014-01-01

    Crop production is obtained from accurate estimates of daily carbon gain.Canopy gross photosynthesis (Pgross) can be estimated from biochemical models of photosynthesis using sun and shaded leaf portions and the amount of intercepted photosyntheticallyactive radiation (PAR).In turn, canopy daily net carbon gain can be estimated from canopy daily gross photosynthesis when canopy dark respiration (Rd) is known.

  15. Respirable dust and respirable silica exposure in Ontario gold mines.

    Science.gov (United States)

    Verma, Dave K; Rajhans, Gyan S; Malik, Om P; des Tombe, Karen

    2014-01-01

    A comprehensive survey of respirable dust and respirable silica in Ontario gold mines was conducted by the Ontario Ministry of Labor during 1978-1979. The aim was to assess the feasibility of introducing gravimetric sampling to replace the assessment method which used konimeters, a device which gave results in terms of number of particles per cubic centimeter (ppcc) of air. The study involved both laboratory and field assessments. The field assessment involved measurement of airborne respirable dust and respirable silica at all eight operating gold mines of the time. This article describes the details of the field assessment. A total of 288 long-term (7-8 hr) personal respirable dust air samples were collected from seven occupational categories in eight gold mines. The respirable silica (α-quartz) was determined by x-ray diffraction method. The results show that during 1978-1979, the industry wide mean respirable dust was about 1 mg/m(3), and the mean respirable silica was 0.08 mg/m(3.)The mean% silica in respirable dust was 7.5%. The data set would be useful in future epidemiological and health studies, as well as in assessment of workers' compensation claims for occupational diseases such as silicosis, chronic obstructive pulmonary disease (COPD), and autoimmune diseases such as renal disease and rheumatoid arthritis.

  16. Level and distribution of employee exposures to total and respirable wood dust in two Canadian sawmills.

    Science.gov (United States)

    Teschke, K; Hertzman, C; Morrison, B

    1994-03-01

    Personal respirable (N = 230) and total (N = 237) dust measurements were made in two coastal British Columbia sawmills using a sampling strategy that randomly selected workers from all jobs in the mills over two seasons. Information about job title, department, season, weather conditions, location of the job relative to wood-cutting machines, and control measures also was collected at the time of sampling. Only 16 respirable wood dust samples were above the detection limit of 0.08 mg/m3; all 16 had levels industry, but most sawmill investigations report mean wood dust concentrations lower than those measured in the furniture and cabinetmaking industries, where concerns about wood dust exposures initially were raised.

  17. Modelo matemático para estimativa da área foliar total de bananeira 'Prata-anã' Esteem method of total leaf area of 'Prata anã' banana tree

    Directory of Open Access Journals (Sweden)

    Moises Zucoloto

    2008-12-01

    Full Text Available O objetivo deste trabalho foi desenvolver um modelo para estimar a área foliar total de bananeira, cultivar Prata-Anã, utilizando dimensões lineares da terceira folha, como o comprimento, a largura e o número total de folhas na emissão da inflorescência. As regressões lineares foram determinadas considerando-se a área foliar total de cada planta (AFT como variável dependente e o comprimento (C e a largura (L da terceira folha, o produto de CxL, o número total de folhas por planta (N e o produto de CxLxN como variáveis independentes. O modelo linear que melhor estimou a área foliar total (AFTe da bananeira 'Prata-Anã', ao nível de 5% de significância com R² de 0,89, foi a equação AFTe = 0,5187(CxLxN + 9603,5.The objective of this work was to estimate the total leaf area of banana, cultivar Prata Anã, according to the linear dimensions of the third leaf, such as the length and the width and the total number of leves in the inflorescence emission. The linear regressions were determined considering total leaf area of each plant (AFT such as dependent variable and the length (C and the width (L of the third leaf, the product of CxL, the total number of leaf per plant (N and the product of CxLxN as independent variables. The best linear model that estimated the total leaf area (AFTe of banana 'Prata Anã' at the level of 5% of significance with R² of 0,89 was the equation AFTe = 0.5187 (CxLxN + 9603.5.

  18. Characterizing the drivers of seedling leaf gas exchange responses to warming and altered precipitation: indirect and direct effects.

    Science.gov (United States)

    Smith, Nicholas G; Pold, Grace; Goranson, Carol; Dukes, Jeffrey S

    2016-01-01

    Anthropogenic forces are projected to lead to warmer temperatures and altered precipitation patterns globally. The impact of these climatic changes on the uptake of carbon by the land surface will, in part, determine the rate and magnitude of these changes. However, there is a great deal of uncertainty in how terrestrial ecosystems will respond to climate in the future. Here, we used a fully factorial warming (four levels) by precipitation (three levels) manipulation experiment in an old-field ecosystem in the northeastern USA to examine the impact of climatic changes on leaf carbon exchange in five species of deciduous tree seedlings. We found that photosynthesis generally increased in response to increasing precipitation and decreased in response to warming. Respiration was less sensitive to the treatments. The net result was greater leaf carbon uptake in wetter and cooler conditions across all species. Structural equation modelling revealed the primary pathway through which climate impacted leaf carbon exchange. Net photosynthesis increased with increasing stomatal conductance and photosynthetic enzyme capacity (V cmax ), and decreased with increasing respiration of leaves. Soil moisture and leaf temperature at the time of measurement most heavily influenced these primary drivers of net photosynthesis. Leaf respiration increased with increasing soil moisture, leaf temperature, and photosynthetic supply of substrates. Counter to the soil moisture response, respiration decreased with increasing precipitation amount, indicating that the response to short- (i.e. soil moisture) versus long-term (i.e. precipitation amount) water stress differed, possibly as a result of changes in the relative amounts of growth and maintenance demand for respiration over time. These data (>500 paired measurements of light and dark leaf gas exchange), now publicly available, detail the pathways by which climate can impact leaf gas exchange and could be useful for testing assumptions in

  19. The Effect of Restoration on Soil Respiration in an Urban Tidal Wetland in the Meadowlands, New Jersey

    Science.gov (United States)

    Schafer, K. V.; Kurepa, S.; Duman, T.; Scott, M.; Pechmann, I.; Vanderklein, D. W.

    2017-12-01

    The effect of wetland restoration on soil respiration in tidal brackish marshes has not been comprehensively studied. In New Jersey, common mitigation efforts come in the form of the removal of an invasive haplotype of Phragmites australis and replanting of native species, resulting in significant habitat disturbance. This study investigated the differences in soil respiration within and between areas covered with P. australis, Spartina alterniflora, and Spartina patens. We performed static chamber measurements of soil respiration using an infrared gas analyzer to measure CO2 fluxes in a natural site and a mitigated site in the Meadowlands of New Jersey. Daytime measurements were performed in 10 random locations in areas populated with each of the vegetation types, to represent the spatial heterogeneity of the wetland area, during summer 2017. Due to the nature of the wetland, vegetation had to be removed to uncover the soil. Prior to measuring exposed soil respiration, we therefore measured CO2 flux including the vegetation within the chamber, which allowed us to additionally calculate the respiration including the vegetation. Furthermore, we assessed direct respiration of green leaves with leaf gas exchange measurements. Combining these different methodologies and scales allow us to estimate the function of different components that contribute to total respiration from the wetland, and how they change spatially and temporally. Initial results showed that soil respiration in P. australis patches was much higher than in both Spartina species, however average vegetation respiration per unit mass was similar across all three. Vegetation respiration and soil respiration are of the same order of magnitude in all three species as well. Also, when respiration with and without vegetation was combined, P. australis showed a considerably higher flux.

  20. Succession after fire: variation in \\delta13C of organic tissues and respired CO2 in boreal forests

    Science.gov (United States)

    Fessenden, J. E.; Li, H.; Mack, M.; Schuur, T.; Warren, S.; Randerson, J. T.

    2001-12-01

    Isotope ratios of carbon dioxide and leaf organic matter were measured in 5 neighboring forests of varying ages: 7, 14, 45, 140, and 160 years. These forests are composed primarily of black spruce (Picea Mariana) and quaking aspen (Populus tremuloides) with a shift in species dominance from aspen to spruce 50 years after fire disturbance. Research on the carbon isotope ratios of leaf material and CO2 was conducted to look for influences from species composition, forest age, and time after most recent burn. Samples of organic \\delta13C in whole leaf tissue were collected from the dominant species of each forest. Concurrent aboveground NPP measurements allowed us to estimate total ecosystem \\delta13C by providing a method for weighting \\delta13C of individual species and plant tissues. \\delta13CO2 and [CO2] were measured on canopy CO2 to determine the isotopic ratio of ecosystem respiration. The atmospheric results indicated that the \\delta13C of ecosystem respiration changes with successional stage. Specifically, the aspen dominating forests showed 13C depleted values relative to the spruce dominated forests. Organic results showed more 13C-enriched values with increased forest age and vegetation functional type. Specifically, oldest trees within the coniferous species had the most 13C-enriched values in leaf tissues. These results suggest that increases in the disturbance regime of northern boreal forests will lead to a decrease in the \\delta13C of ecosystem carbon with consequences for the atmospheric \\delta13C budget.

  1. Measurements methods and variability assesment of the Norway spruce total leaf area. Implications for remote sensing

    Czech Academy of Sciences Publication Activity Database

    Homolová, L.; Lukeš, Petr; Malenovský, Z.; Lhotáková, Z.; Kaplan, Věroslav; Hanuš, Jan

    2013-01-01

    Roč. 27, č. 1 (2013), s. 111-121 ISSN 0931-1890 R&D Projects: GA ČR GA205/09/ 1989 Institutional support: RVO:67179843 Keywords : chlorophyll content * conversion factor * Picea abies * projected leaf area * remote sensing * total leaf area Subject RIV: EH - Ecology, Behaviour Impact factor: 1.869, year: 2013

  2. Contribution of bacterial respiration to plankton respiration from 50°N to 44°S in the Atlantic Ocean

    Science.gov (United States)

    García-Martín, E. E.; Aranguren-Gassis, M.; Hartmann, M.; Zubkov, M. V.; Serret, P.

    2017-11-01

    Marine bacteria play an important role in the global cycling of carbon and therefore in climate regulation. However, the paucity of direct measurements means that our understanding of the magnitude and variability of bacterial respiration in the ocean is poor. Estimations of respiration in the 0.2-0.8 μm size-fraction (considered as bacterial respiration), total plankton community respiration, and the contribution of bacterial respiration to total plankton community respiration were made along two latitudinal transects in the Atlantic Ocean (ca. 50°N-44°S) during 2010 and 2011. Two different methodologies were used: determination of changes in dissolved O2 concentration after standard 24 h dark bottle incubations, and measurements of in vivo reduction of 2-(ρ-iodophenyl)-3-(ρ-nitrophenyl)-5phenyl tetrazolium salt (INT). There was an overall significant correlation (r = 0.44, p community respiration estimated by both methods. Depth-integrated community respiration varied as much as threefold between regions. Maximum rates occurred in waters of the western European shelf and Patagonian shelf, and minimum rates in the North and South oligotrophic gyres. Depth-integrated bacterial respiration followed the same pattern as community respiration. There was a significantly higher cell-specific bacterial respiration in the northern subtropical gyre than in the southern subtropical gyre which suggests that bacterial carbon turnover is faster in the northern gyre. The relationships between plankton respiration and physicochemical and biological variables were different in different years. In general, INTT was correlated to both chlorophyll-a and bacterial abundance, while INT0.2-0.8 was only correlated with bacterial abundance. However, in 2010 INTT and INT0.2-0.8 were also correlated with temperature and primary production while in 2011 they were correlated with nitrate + nitrite concentration. The bacterial contribution to depth integrated community respiration was

  3. Canopy position affects the relationships between leaf respiration and associated traits in a tropical rainforest in Far North Queensland.

    Science.gov (United States)

    Weerasinghe, Lasantha K; Creek, Danielle; Crous, Kristine Y; Xiang, Shuang; Liddell, Michael J; Turnbull, Matthew H; Atkin, Owen K

    2014-06-01

    We explored the impact of canopy position on leaf respiration (R) and associated traits in tree and shrub species growing in a lowland tropical rainforest in Far North Queensland, Australia. The range of traits quantified included: leaf R in darkness (RD) and in the light (RL; estimated using the Kok method); the temperature (T)-sensitivity of RD; light-saturated photosynthesis (Asat); leaf dry mass per unit area (LMA); and concentrations of leaf nitrogen (N), phosphorus (P), soluble sugars and starch. We found that LMA, and area-based N, P, sugars and starch concentrations were all higher in sun-exposed/upper canopy leaves, compared with their shaded/lower canopy and deep-shade/understory counterparts; similarly, area-based rates of RD, RL and Asat (at 28 °C) were all higher in the upper canopy leaves, indicating higher metabolic capacity in the upper canopy. The extent to which light inhibited R did not differ significantly between upper and lower canopy leaves, with the overall average inhibition being 32% across both canopy levels. Log-log RD-Asat relationships differed between upper and lower canopy leaves, with upper canopy leaves exhibiting higher rates of RD for a given Asat (both on an area and mass basis), as well as higher mass-based rates of RD for a given [N] and [P]. Over the 25-45 °C range, the T-sensitivity of RD was similar in upper and lower canopy leaves, with both canopy positions exhibiting Q10 values near 2.0 (i.e., doubling for every 10 °C rise in T) and Tmax values near 60 °C (i.e., T where RD reached maximal values). Thus, while rates of RD at 28 °C decreased with increasing depth in the canopy, the T-dependence of RD remained constant; these findings have important implications for vegetation-climate models that seek to predict carbon fluxes between tropical lowland rainforests and the atmosphere. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  4. An extended PROSPECT: Advance in the leaf optical properties model separating total chlorophylls into chlorophyll a and b.

    Science.gov (United States)

    Zhang, Yao; Huang, Jingfeng; Wang, Fumin; Blackburn, George Alan; Zhang, Hankui K; Wang, Xiuzhen; Wei, Chuanwen; Zhang, Kangyu; Wei, Chen

    2017-07-25

    The PROSPECT leaf optical model has, to date, well-separated the effects of total chlorophyll and carotenoids on leaf reflectance and transmittance in the 400-800 nm. Considering variations in chlorophyll a:b ratio with leaf age and physiological stress, a further separation of total plant-based chlorophylls into chlorophyll a and chlorophyll b is necessary for advanced monitoring of plant growth. In this study, we present an extended version of PROSPECT model (hereafter referred to as PROSPECT-MP) that can combine the effects of chlorophyll a, chlorophyll b and carotenoids on leaf directional hemispherical reflectance and transmittance (DHR and DHT) in the 400-800 nm. The LOPEX93 dataset was used to evaluate the capabilities of PROSPECT-MP for spectra modelling and pigment retrieval. The results show that PROSPECT-MP can both simultaneously retrieve leaf chlorophyll a and b, and also performs better than PROSPECT-5 in retrieving carotenoids concentrations. As for the simulation of DHR and DHT, the performances of PROSPECT-MP are similar to that of PROSPECT-5. This study demonstrates the potential of PROSPECT-MP for improving capabilities of remote sensing of leaf photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids) and for providing a framework for future refinements in the modelling of leaf optical properties.

  5. Toward the definition of a carbon budget model: seasonal variation and temperature effect on respiration rate of vegetative and reproductive organs of pistachio trees (Pistacia vera).

    Science.gov (United States)

    Marra, Francesco P; Barone, Ettore; La Mantia, Michele; Caruso, Tiziano

    2009-09-01

    This study, as a preliminary step toward the definition of a carbon budget model for pistachio trees (Pistacia vera L.), aimed at estimating and evaluating the dynamics of respiration of vegetative and reproductive organs of pistachio tree. Trials were performed in 2005 in a commercial orchard located in Sicily (370 m a.s.l.) on five bearing 20-year-old pistachio trees of cv. Bianca grafted onto Pistachio terebinthus L. Growth analyses and respiration measurements were done on vegetative (leaf) and reproductive (infructescence) organs during the entire growing season (April-September) at biweekly intervals. Results suggested that the respiration rates of pistachio reproductive and vegetative organs were related to their developmental stage. Both for leaf and for infructescence, the highest values were observed during the earlier stages of growth corresponding to the phases of most intense organ growth. The sensitivity of respiration activity to temperature changes, measured by Q(10), showed an increase throughout the transition from immature to mature leaves, as well as during fruit development. The data collected were also used to estimate the seasonal carbon loss by respiration activity for a single leaf and a single infructescence. The amount of carbon lost by respiration was affected by short-term temperature patterns, organ developmental stage and tissue function.

  6. In vitro antioxidant evaluation and total phenolics of methanolic leaf extracts of Nyctanthes arbor-tristis L.

    Science.gov (United States)

    Michael, J Savarimuthu; Kalirajan, A; Padmalatha, C; Singh, A J A Ranjit

    2013-09-01

    To investigate the in vitro antioxidant activity and total phenolic content of the methanolic leaf extract of Nyctanthes arbor-tristis L. (NA). The sample was tested using five in vitro antioxidant methods (1, 1-diphenyl-2-picryl hydrazine radical scavenging activity (DPPH), hydroxyl radical-scavenging activity (-OH), nitric oxide scavenging activity (NO), superoxide radical-scavenging activity, and total antioxidant activity) to evaluate the in vitro antioxidant potential of NA and the total phenolic content (Folin-Ciocalteu method). The extract showed good free radical scavenging property which was calculated as an IC50 value. IC50 (Half maximal inhibitory concentration) of the methanolic extract was found to be 57.93 μg·mL(-1) for DPPH, 98.61 μg·mL(-1) for -OH, 91.74 μg·mL(-1) for NO, and 196.07 μg·mL(-1) for superoxide radical scavenging activity. Total antioxidant capacity of the extract was found to be (1198 ± 24.05) mg ascorbic acid for the methanolic extract. Free radical scavenging activity observed in the extracts of NA showed a concentration-dependent reaction. The in vitro scavenging tested for free radicals was reported to be due to high phenolic content in the leaf extract. The leaf extract of NA showed the highest total phenolic content with a value of 78.48 ± 4.2 equivalent mg TAE/g (tannic acid equivalent). N. arbor-tristis leaf extract exhibited potent free radical scavenging activity. The finding suggests that N. arbor-tristis leaves could be a potential source of natural antioxidant. Copyright © 2013 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

  7. 75 FR 29699 - Total Inward Leakage Requirements for Respirators

    Science.gov (United States)

    2010-05-27

    ... or other half-mask respirator inward leakage measurement, and offer any additional comments on the..., facsimile (412) 386-4089, e-mail [email protected] . SUPPLEMENTARY INFORMATION: I. Background The Department of... order to conduct tests and prepare responses. On April 20, 2010, NIOSH responded by reopening the docket...

  8. Plant-pathogen interactions: leaf physiology alterations in poplars infected with rust (Melampsora medusae).

    Science.gov (United States)

    Gortari, Fermín; Guiamet, Juan José; Graciano, Corina

    2018-01-23

    Rust produced by Melampsora sp. is considered one of the most relevant diseases in poplar plantations. Growth reduction in poplar plantations takes place because rust, like other pathogens, alters leaf physiology. There is not a complete evaluation of several of the physiological traits that can be affected by rust at leaf level. Therefore, the aim of this work was to evaluate, in an integrative way and in the same pathosystem, which physiological processes are affected when Populus deltoides Bartr. ex Marsh. leaves are infected by rust (Melampsora medusae Thümen). Leaves of two clones with different susceptibility to rust were analyzed. Field and pot experiments were performed, and several physiological traits were measured in healthy and infected leaves. We conclude that rust affects leaf mesophyll integrity, and so water movement in the leaf in liquid phase is affected. As a consequence, gas exchange is reduced, affecting both carbon fixation and transpiration. However, there is an increase in respiration rate, probably due to plant and fungal respiration. The increase in respiration rate is important in the reduction of net photosynthetic rate, but also some damage in the photosynthetic apparatus limits leaf capacity to fix carbon. The decrease in chlorophyll content would start later and seems not to explain the reduction in net photosynthetic rate. Both clones, although they have different susceptibility to rust, are affected in the same physiological mechanisms. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  9. Soil respiration in northern forests exposed to elevated atmospheric carbon dioxide and ozone.

    Science.gov (United States)

    Pregitzer, Kurt; Loya, Wendy; Kubiske, Mark; Zak, Donald

    2006-06-01

    The aspen free-air CO2 and O3 enrichment (FACTS II-FACE) study in Rhinelander, Wisconsin, USA, is designed to understand the mechanisms by which young northern deciduous forest ecosystems respond to elevated atmospheric carbon dioxide (CO2) and elevated tropospheric ozone (O3) in a replicated, factorial, field experiment. Soil respiration is the second largest flux of carbon (C) in these ecosystems, and the objective of this study was to understand how soil respiration responded to the experimental treatments as these fast-growing stands of pure aspen and birch + aspen approached maximum leaf area. Rates of soil respiration were typically lowest in the elevated O3 treatment. Elevated CO2 significantly stimulated soil respiration (8-26%) compared to the control treatment in both community types over all three growing seasons. In years 6-7 of the experiment, the greatest rates of soil respiration occurred in the interaction treatment (CO2 + O3), and rates of soil respiration were 15-25% greater in this treatment than in the elevated CO2 treatment, depending on year and community type. Two of the treatments, elevated CO2 and elevated CO2 + O3, were fumigated with 13C-depleted CO2, and in these two treatments we used standard isotope mixing models to understand the proportions of new and old C in soil respiration. During the peak of the growing season, C fixed since the initiation of the experiment in 1998 (new C) accounted for 60-80% of total soil respiration. The isotope measurements independently confirmed that more new C was respired from the interaction treatment compared to the elevated CO2 treatment. A period of low soil moisture late in the 2003 growing season resulted in soil respiration with an isotopic signature 4-6 per thousand enriched in 13C compared to sample dates when the percentage soil moisture was higher. In 2004, an extended period of low soil moisture during August and early September, punctuated by a significant rainfall event, resulted in soil

  10. Relationships between Personal Measurements of 'Total' Dust, Respirable, Thoracic, and Inhalable Aerosol Fractions in the Cement Production Industry.

    Science.gov (United States)

    Notø, Hilde P; Nordby, Karl-Christian; Eduard, Wijnand

    2016-05-01

    The aims of this study were to examine the relationships and establish conversion factors between 'total' dust, respirable, thoracic, and inhalable aerosol fractions measured by parallel personal sampling on workers from the production departments of cement plants. 'Total' dust in this study refers to aerosol sampled by the closed face 37-mm Millipore filter cassette. Side-by-side personal measurements of 'total' dust and respirable, thoracic, and inhalable aerosol fractions were performed on workers in 17 European and Turkish cement plants. Simple linear and mixed model regressions were used to model the associations between the samplers. The total number of personal samples collected on 141 workers was 512. Of these 8.4% were excluded leaving 469 for statistical analysis. The different aerosol fractions contained from 90 to 130 measurements and-side-by side measurements of all four aerosol fractions were collected on 72 workers.The median ratios between observed results of the respirable, 'total' dust, and inhalable fractions relative to the thoracic aerosol fractions were 0.51, 2.4, and 5.9 respectively. The ratios between the samplers were not constant over the measured concentration range and were best described by regression models. Job type, position of samplers on left or right shoulder and plant had no substantial effect on the ratios. The ratios between aerosol fractions changed with different air concentrations. Conversion models for estimation of the fractions were established. These models explained a high proportion of the variance (74-91%) indicating that they are useful for the estimation of concentrations based on measurements of a different aerosol fraction. The calculated uncertainties at most observed concentrations were below 30% which is acceptable for comparison with limit values (EN 482, 2012). The cement industry will therefore be able to predict the health related aerosol fractions from their former or future measurements of one of the

  11. Effects of fluoride and 6 benzylaminopurine on growth and respiration of corn and cotton roots

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, C R

    1967-01-01

    Corn and cotton plants exhibit a wide difference in their susceptibility to atmospheric fluoride. Corn shows leaf lesions when 100 ..gamma../gm on a dry weight basis are accumulated but cotton can tolerate 5000 ..gamma../gm without showing leaf necrosis. A comparison of respirational response of potted seedlings of the two species to 10 ..gamma../M/sup 3/ HF caused an increase of about 10%. Addition of 2 x 10/sup 2/M F/sup -/ to solutions for germinating the plants showed that cotton accumulated about twice as much as F/sup -/ in seedling roots. Growth was reduced about one half by 2 x 10/sup -3/M F/sup -/ in both species but respirational rates of root tips from control and fluoride treated tissues were equal. Prolonged treatment of excised root tips with fluoride reduced respiration. Because fluoride causes cellular changes in roots similar to aging and kinetin seems to act to reverse these changes, corn was germinated with 2 x 10/sup -3/M F/sup -/ and increasing levels of 6-benzylaminopurine. Root growth inhibition (63%) was reversed significantly at 0.2 - 0.8..gamma.. ml. Respirational rates of root tips grown in fluoride, fluoride plus 6-benzylaminopurine and controls were equal.

  12. Variations in dark respiration and mitochondrial numbers within needles of Pinus radiata grown in ambient or elevated CO2 partial pressure

    International Nuclear Information System (INIS)

    Griffin, K. L.; Anderson, O. R.; Tissue, D. T.; Turnbull, M. H.; Whitehead, D.

    2004-01-01

    An experiment involving comparison of within-leaf variations in cell size, mitochondrial numbers and dark respiration in the most recently expanded tip, the mid-section and the base of needles of Pinus radiata grown for four years at ambient and elevated carbon dioxide partial pressure, is described. Results showed variation in mitochondrial numbers and respiration along the length of the needle, with the highest number of mitochondria per unit cytoplasm and the highest rate of respiration per unit leaf area at the base of the needle. Elevated carbon dioxide pressure caused the number of mitochondria per unit cytoplasm to double regardless of location (tip, basal or mid sections). Under these conditions, greatest mitochondrial density was observed at the tip. The mean size of mitochondria was not affected by either growth at elevated carbon dioxide pressure or by position on the needle. Respiration per unit leaf area at elevated carbon dioxide pressure was highest at the tip of needles, decreasing towards the middle and basal sections. The observed data supports the hypothesis that the highest number of mitochondria per unit area of cytoplasm occurs at the base of the needle, but does not support the hypothesis that the lowest rate of respiration also occurs at the base. It is suggested that the relationship that determines the association between structure and function in these needles is more complex than previously thought. 33 refs., 4 tabs., 1 fig

  13. Drought Sensitivity of the Carbon Isotope Composition of Leaf Dark-Respired CO2 in C3 (Leymus chinensis and C4 (Chloris virgata and Hemarthria altissima Grasses in Northeast China

    Directory of Open Access Journals (Sweden)

    Shangzhi Zhong

    2017-12-01

    Full Text Available Whether photosynthetic pathway differences exist in the amplitude of nighttime variations in the carbon isotope composition of leaf dark-respired CO2 (δ13Cl and respiratory apparent isotope fractionation relative to biomass (ΔR,biomass in response to drought stress is unclear. These differences, if present, would be important for the partitioning of C3-C4 mixed ecosystem C fluxes. We measured δ13Cl, the δ13C of biomass and of potential respiratory substrates and leaf gas exchange in one C3 (Leymus chinensis and two C4 (Chloris virgata and Hemarthria altissima grasses during a manipulated drought period. For all studied grasses, δ13Cl decreased from 21:00 to 03:00 h. The magnitude of the nighttime shift in δ13Cl decreased with increasing drought stress. The δ13Cl values were correlated with the δ13C of respiratory substrates, whereas the magnitude of the nighttime shift in δ13Cl strongly depended on the daytime carbon assimilation rate and the range of nighttime variations in the respiratory substrate content. The ΔR,biomass in the C3 and C4 grasses varied in opposite directions with the intensification of the drought stress. The contribution of C4 plant-associated carbon flux is likely to be overestimated if carbon isotope signatures are used for the partitioning of ecosystem carbon exchange and the δ13C of biomass is used as a substitute for leaf dark-respired CO2. The detected drought sensitivities in δ13Cl and differences in respiratory apparent isotope fractionation between C3 and C4 grasses have marked implications for isotope partitioning studies at the ecosystem level.

  14. Drought Sensitivity of the Carbon Isotope Composition of Leaf Dark-Respired CO2 in C3 (Leymus chinensis) and C4 (Chloris virgata and Hemarthria altissima) Grasses in Northeast China.

    Science.gov (United States)

    Zhong, Shangzhi; Chai, Hua; Xu, Yueqiao; Li, Yan; Ma, Jian-Ying; Sun, Wei

    2017-01-01

    Whether photosynthetic pathway differences exist in the amplitude of nighttime variations in the carbon isotope composition of leaf dark-respired CO 2 (δ 13 C l ) and respiratory apparent isotope fractionation relative to biomass (Δ R,biomass ) in response to drought stress is unclear. These differences, if present, would be important for the partitioning of C 3 -C 4 mixed ecosystem C fluxes. We measured δ 13 C l , the δ 13 C of biomass and of potential respiratory substrates and leaf gas exchange in one C 3 ( Leymus chinensis ) and two C 4 ( Chloris virgata and Hemarthria altissima ) grasses during a manipulated drought period. For all studied grasses, δ 13 C l decreased from 21:00 to 03:00 h. The magnitude of the nighttime shift in δ 13 C l decreased with increasing drought stress. The δ 13 C l values were correlated with the δ 13 C of respiratory substrates, whereas the magnitude of the nighttime shift in δ 13 C l strongly depended on the daytime carbon assimilation rate and the range of nighttime variations in the respiratory substrate content. The Δ R,biomass in the C 3 and C 4 grasses varied in opposite directions with the intensification of the drought stress. The contribution of C 4 plant-associated carbon flux is likely to be overestimated if carbon isotope signatures are used for the partitioning of ecosystem carbon exchange and the δ 13 C of biomass is used as a substitute for leaf dark-respired CO 2 . The detected drought sensitivities in δ 13 C l and differences in respiratory apparent isotope fractionation between C 3 and C 4 grasses have marked implications for isotope partitioning studies at the ecosystem level.

  15. LCE: leaf carbon exchange data set for tropical, temperate, and boreal species of North and Central America.

    Science.gov (United States)

    Smith, Nicholas G; Dukes, Jeffrey S

    2017-11-01

    Leaf canopy carbon exchange processes, such as photosynthesis and respiration, are substantial components of the global carbon cycle. Climate models base their simulations of photosynthesis and respiration on an empirical understanding of the underlying biochemical processes, and the responses of those processes to environmental drivers. As such, data spanning large spatial scales are needed to evaluate and parameterize these models. Here, we present data on four important biochemical parameters defining leaf carbon exchange processes from 626 individuals of 98 species at 12 North and Central American sites spanning ~53° of latitude. The four parameters are the maximum rate of Rubisco carboxylation (V cmax ), the maximum rate of electron transport for the regeneration of Ribulose-1,5,-bisphosphate (J max ), the maximum rate of phosphoenolpyruvate carboxylase carboxylation (V pmax ), and leaf dark respiration (R d ). The raw net photosynthesis by intercellular CO 2 (A/C i ) data used to calculate V cmax , J max , and V pmax rates are also presented. Data were gathered on the same leaf of each individual (one leaf per individual), allowing for the examination of each parameter relative to others. Additionally, the data set contains a number of covariates for the plants measured. Covariate data include (1) leaf-level traits (leaf mass, leaf area, leaf nitrogen and carbon content, predawn leaf water potential), (2) plant-level traits (plant height for herbaceous individuals and diameter at breast height for trees), (3) soil moisture at the time of measurement, (4) air temperature from nearby weather stations for the day of measurement and each of the 90 d prior to measurement, and (5) climate data (growing season mean temperature, precipitation, photosynthetically active radiation, vapor pressure deficit, and aridity index). We hope that the data will be useful for obtaining greater understanding of the abiotic and biotic determinants of these important biochemical

  16. How do leaf veins influence the worldwide leaf economic spectrum? Review and synthesis.

    Science.gov (United States)

    Sack, Lawren; Scoffoni, Christine; John, Grace P; Poorter, Hendrik; Mason, Chase M; Mendez-Alonzo, Rodrigo; Donovan, Lisa A

    2013-10-01

    Leaf vein traits are implicated in the determination of gas exchange rates and plant performance. These traits are increasingly considered as causal factors affecting the 'leaf economic spectrum' (LES), which includes the light-saturated rate of photosynthesis, dark respiration, foliar nitrogen concentration, leaf dry mass per area (LMA) and leaf longevity. This article reviews the support for two contrasting hypotheses regarding a key vein trait, vein length per unit leaf area (VLA). Recently, Blonder et al. (2011, 2013) proposed that vein traits, including VLA, can be described as the 'origin' of the LES by structurally determining LMA and leaf thickness, and thereby vein traits would predict LES traits according to specific equations. Careful re-examination of leaf anatomy, published datasets, and a newly compiled global database for diverse species did not support the 'vein origin' hypothesis, and moreover showed that the apparent power of those equations to predict LES traits arose from circularity. This review provides a 'flux trait network' hypothesis for the effects of vein traits on the LES and on plant performance, based on a synthesis of the previous literature. According to this hypothesis, VLA, while virtually independent of LMA, strongly influences hydraulic conductance, and thus stomatal conductance and photosynthetic rate. We also review (i) the specific physiological roles of VLA; (ii) the role of leaf major veins in influencing LES traits; and (iii) the role of VLA in determining photosynthetic rate per leaf dry mass and plant relative growth rate. A clear understanding of leaf vein traits provides a new perspective on plant function independently of the LES and can enhance the ability to explain and predict whole plant performance under dynamic conditions, with applications towards breeding improved crop varieties.

  17. Relative Sensitivity of Photosynthesis and Respiration to Freeze-Thaw Stress in Herbaceous Species 1

    Science.gov (United States)

    Steffen, Kenneth L.; Arora, Rajeev; Palta, Jiwan P.

    1989-01-01

    The relative effect of a freeze-thaw cycle on photosynthesis, respiration, and ion leakage of potato leaf tissue was examined in two potato species, Solanum acaule Bitt. and Solanum commersonii Dun. Photosynthesis was found to be much more sensitive to freezing stress than was respiration, and demonstrated more than a 60% inhibition before any impairment of respiratory function was observed. Photosynthesis showed a slight to moderate inhibition when only 5 to 10% of the total electrolytes had leaked from the tissue (reversible injury). This was in contrast to respiration which showed no impairment until temperatures at which about 50% ion leakage (irreversible injury) had occurred. The influence of freeze-thaw protocol was further examined in S. acaule and S. commersonii, in order to explore discrepancies in the literature as to the relative sensitivities of photosynthesis and respiration. As bath cooling rates increased from 1°C/hour to about 3 or 6°C/hour, there was a dramatic increase in the level of damage to all measured cellular functions. The initiation of ice formation in deeply supercooled tissue caused even greater damage. As the cooling rates used in stress treatments increased, the differential sensitivity between photosynthesis and respiration nearly disappeared. Examination of agriculturally relevant, climatological data from an 11 year period confirmed that air cooling rates in the freezing range do not exceed 2°C/hour. It was demonstrated, in the studies presented here, that simply increasing the actual cooling rate from 1.0 to 2.9°C/hour, in frozen tissue from paired leaflet halves, meant the difference between cell survival and cell death. Images Figure 4 Figure 5 PMID:16666712

  18. Environmental controls of daytime leaf carbon exchange: Implications for estimates of ecosystem fluxes in a deciduous forest

    Science.gov (United States)

    Heskel, M.; Tang, J.

    2017-12-01

    Leaf-level photosynthesis and respiration are sensitive to short- and long-term changed in temperature, and how these processes respond to phenological and seasonal transitions and daily temperature variation dictate how carbon is first assimilated and released in terrestrial ecosystems. We examined the short-term temperature response of daytime leaf carbon exchange at Harvard Forest across growing season, with the specific objective to quantify the light inhibition of dark respiration and photorespiration in leaves and use this to better inform daytime carbon assimilation and efflux estimates at the canopy scale. Dark and light respiration increased with measurement temperature and varied seasonally in a proportional manner, with the level of inhibition remaining relatively constant through the growing season. Higher rates of mitochondrial respiration and photorespiration at warmer temperatures drove a lower carbon use efficiency. Using temperature, light, and canopy leaf area index values to drive models, we estimate partitioned ecosystem fluxes and re-calculate gross primary production under multiple scenarios that include and exclude the impact of light inhibition, thermal acclimation, and seasonal variation in physiology. Quantifying the contribution of these `small fluxes' to ecosystem carbon exchange in forests provides a nuanced approach for integrating physiology into regional model estimates derived from eddy covariance and remote-sensing methods.

  19. Determination of total phenolic content and antioxidant activitity of methanol extract of Maranta arundinacea L fresh leaf and tuber

    Science.gov (United States)

    Kusbandari, A.; Susanti, H.

    2017-11-01

    Maranta arundinacea L is one of herbaceous plants in Indonesia which have flavonoid content. Flavonoids has antioxidants activity by inhibition of free radical oxidation reactions. The study aims were to determination total phenolic content and antioxidant activity of methanol extract of fresh leaf and tuber of M. arundinacea L by UV-Vis spectrophotometer. The methanol extracts were obtained with maceration and remaseration method of fresh leaves and tubers. The total phenolic content was assayed with visible spectrophotometric using Folin Ciocalteau reagent. The antioxidant activity was assayed with 1,1-diphenyl-2-picrilhidrazil (DPPH) compared to gallic acid. The results showed that methanol extract of tuber and fresh leaf of M. arundinacea L contained phenolic compound with total phenolic content (TPC) in fresh tuber of 3.881±0.064 (% GAE) and fresh leaf is 6.518±0.163 (% b/b GAE). IC50 value from fresh tuber is 1.780±0.0005 μg/mL and IC50 fresh leaf values of 0.274±0.0004 μg/mL while the standard gallic acid is IC50 of 0.640±0.0002 μg/mL.

  20. Temperature dependence of bulk respiration of crop stands. Measurement and model fitting

    International Nuclear Information System (INIS)

    Tani, Takashi; Arai, Ryuji; Tako, Yasuhiro

    2007-01-01

    The objective of the present study was to examine whether the temperature dependence of respiration at a crop-stand scale could be directly represented by an Arrhenius function that was widely used for representing the temperature dependence of leaf respiration. We determined temperature dependences of bulk respiration of monospecific stands of rice and soybean within a range of the air temperature from 15 to 30degC using large closed chambers. Measured responses of respiration rates of the two stands were well fitted by the Arrhenius function (R 2 =0.99). In the existing model to assess the local radiological impact of the anthropogenic carbon-14, effects of the physical environmental factors on photosynthesis and respiration of crop stands are not taken into account for the calculation of the net amount of carbon per cultivation area in crops at harvest which is the crucial parameter for the estimation of the activity concentration of carbon-14 in crops. Our result indicates that the Arrhenius function is useful for incorporating the effect of the temperature on respiration of crop stands into the model which is expected to contribute to a more realistic estimate of the activity concentration of carbon-14 in crops. (author)

  1. Drought increases heat tolerance of leaf respiration in Eucalyptus globulus saplings grown under both ambient and elevated atmospheric [CO2] and temperature

    Science.gov (United States)

    Gauthier, Paul P. G.; Crous, Kristine Y.; Ayub, Gohar; Duan, Honglang; Weerasinghe, Lasantha K.; Ellsworth, David S.; Tjoelker, Mark G.; Evans, John R.; Tissue, David T.; Atkin, Owen K.

    2014-01-01

    Climate change is resulting in increasing atmospheric [CO2], rising growth temperature (T), and greater frequency/severity of drought, with each factor having the potential to alter the respiratory metabolism of leaves. Here, the effects of elevated atmospheric [CO2], sustained warming, and drought on leaf dark respiration (R dark), and the short-term T response of R dark were examined in Eucalyptus globulus. Comparisons were made using seedlings grown under different [CO2], T, and drought treatments. Using high resolution T–response curves of R dark measured over the 15–65 °C range, it was found that elevated [CO2], elevated growth T, and drought had little effect on rates of R dark measured at T CO2], growth T, and drought on T response of R dark. However, drought increased R dark at high leaf T typical of heatwave events (35–45 °C), and increased the measuring T at which maximal rates of R dark occurred (T max) by 8 °C (from 52 °C in well-watered plants to 60 °C in drought-treated plants). Leaf starch and soluble sugars decreased under drought and elevated growth T, respectively, but no effect was found under elevated [CO2]. Elevated [CO2] increased the Q 10 of R dark (i.e. proportional rise in R dark per 10 °C) over the 15–35 °C range, while drought increased Q 10 values between 35 °C and 45 °C. Collectively, the study highlights the dynamic nature of the T dependence of R dark in plants experiencing future climate change scenarios, particularly with respect to drought and elevated [CO2]. PMID:25205579

  2. Cardiac, Skeletal, and smooth muscle mitochondrial respiration

    DEFF Research Database (Denmark)

    Park, Song-Young; Gifford, Jayson R; Andtbacka, Robert H I

    2014-01-01

    , skeletal, and smooth muscle was harvested from a total of 22 subjects (53±6 yrs) and mitochondrial respiration assessed in permeabilized fibers. Complex I+II, state 3 respiration, an index of oxidative phosphorylation capacity, fell progressively from cardiac, skeletal, to smooth muscle (54±1; 39±4; 15......±1 pmol•s(-1)•mg (-1), prespiration rates were normalized by CS (respiration...... per mitochondrial content), oxidative phosphorylation capacity was no longer different between the three muscle types. Interestingly, Complex I state 2 normalized for CS activity, an index of non-phosphorylating respiration per mitochondrial content, increased progressively from cardiac, skeletal...

  3. Contribution of orchardgrass and white clover roots to total soil respiration

    Science.gov (United States)

    Understanding ecosystem carbon dioxide flux requires knowledge of component fluxes including photosynthetic uptake and respiratory loss. Experimental separation of soil respiration into its heterotrophic and autotrophic components has been difficult, complicating efforts to quantify management and e...

  4. Low light availability affects leaf gas exchange, growth and survival ...

    African Journals Online (AJOL)

    The values of dark respiration rate (Rd) and photosynthetic compensation irradiance (Ic) were sufficiently low for a positive carbon balance. Notwithstanding, the interpretation of results of microclimate variables together with leaf gas exchange and growth variables indicated that seedlings at all sites were in a suboptimal ...

  5. Persistent reduced ecosystem respiration after insect disturbance in high elevation forests.

    Science.gov (United States)

    Moore, David J P; Trahan, Nicole A; Wilkes, Phil; Quaife, Tristan; Stephens, Britton B; Elder, Kelly; Desai, Ankur R; Negron, Jose; Monson, Russell K

    2013-06-01

    Amid a worldwide increase in tree mortality, mountain pine beetles (Dendroctonus ponderosae Hopkins) have led to the death of billions of trees from Mexico to Alaska since 2000. This is predicted to have important carbon, water and energy balance feedbacks on the Earth system. Counter to current projections, we show that on a decadal scale, tree mortality causes no increase in ecosystem respiration from scales of several square metres up to an 84 km(2) valley. Rather, we found comparable declines in both gross primary productivity and respiration suggesting little change in net flux, with a transitory recovery of respiration 6-7 years after mortality associated with increased incorporation of leaf litter C into soil organic matter, followed by further decline in years 8-10. The mechanism of the impact of tree mortality caused by these biotic disturbances is consistent with reduced input rather than increased output of carbon. © 2013 John Wiley & Sons Ltd/CNRS.

  6. Can we distinguish autotrophic respiration from heterotrophic respiration in a field site using high temporal resolution CO2 flux measurements?

    Science.gov (United States)

    Biro, Beatrice; Berger, Sina; Praetzel, Leandra; Blodau, Christian

    2016-04-01

    The processes behind C-cycling in peatlands are important to understand for assessing the vulnerability of peatlands as carbon sinks under changing climate conditions. Especially boreal peatlands are likely to underlie strong alterations in the future. It is expected that C-pools that are directly influenced by vegetation and water table fluctuations can be easily destabilized. The CO2 efflux through respiration underlies autotrophic and heterotrophic processes that show different feedbacks on changing environmental conditions. In order to understand the respiration fluxes better for more accurate modelling and prognoses, the determination of the relative importance of different respiration sources is necessary. Earlier studies used e.g. exfoliation experiments, incubation experiments or modelling approaches to estimate the different respiration sources for the total ecosystem respiration (Reco). To further the understanding in this topic, I want to distinguish autotrophic and heterotrophic respiration using high temporal resolution measurements. The study site was selected along a hydrological gradient in a peatland in southern Ontario (Canada) and measurements were conducted from May to September 2015 once per month. Environmental controls (water table, soil temperature and soil moisture) that effect the respiration sources were recorded. In my study I used a Li-COR 6400XT and a Los Gatos greenhouse gas analyzer (GGA). Reco was determined by chamber flux measurements with the GGA, while simultaneously CO2 respiration measurements on different vegetation compartments like roots, leaves and mosses were conducted using the Li-COR 6400XT. The difference between Reco and autotrophic respiration equals heterotrophic respiration. After the measurements, the vegetation plots were harvested and separated for all compartments (leaves, roots, mosses, soil organic matter), dried and weighed. The weighted respiration rates from all vegetation compartments sum up to

  7. Respirable versus inhalable dust sampling

    International Nuclear Information System (INIS)

    Hondros, J.

    1987-01-01

    The ICRP uses a total inhalable dust figure as the basis of calculations on employee lung dose. This paper was written to look at one aspect of the Olympic Dam dust situation, namely, the inhalable versus respirable fraction of the dust cloud. The results of this study will determine whether it is possible to use respirable dust figures, as obtained during routine monitoring to help in the calculations of employee exposure to internal radioactive contaminants

  8. [Effects of simulated warming on the growth, leaf phenology, and leaf traits of Salix eriostachya in sub-alpine timberline ecotone of western Sichuan, China].

    Science.gov (United States)

    Xu, Zhen-feng; Hu, Ting-xing; Zhang, Li; Zhang, Yuan-bin; Xian, Jun-ren; Wang, Kai-yun

    2009-01-01

    By using open-top chamber (OTC), the effects of simulated warming on the growth, leaf phenology, and leaf traits of Salix eriostachya in sub-alpine timberline ecotone of Western Sichuan were studied. The results showed that comparing with the control, the mean air temperature at 1.2 m above the ground throughout S. eriostachya growth season in OTC increased by 2.9 degrees C, while the soil temperature at the depth of 5 cm only increased by 0.4 degrees C. The temperature increase in OTC made S. eriostachya budding advanced and defoliation postponed obviously, and the leaf life-span longer. The leaf and branch growth rates as well as the specific leaf area in OTC increased obviously, whereas the leaf nitrogen concentration decreased significantly. In OTC, the stomata conductance, net photosynthetic rate, photorespiration, and dark respiration rate of S. eriostachya all exhibited an increasing trend. It was suggested that S. eriostachya had stronger capability to adapt to warming, and, under the background of future global climate change, the elevation of S. eriostachya distribution in the timberline ecotone would be likely to ascend.

  9. Contribution of root to soil respiration and carbon balance in ...

    Indian Academy of Sciences (India)

    Soil respiration varied from 2.5 to 11.9 g CO2 m-2 d-1 and from 1.5 to 9.3 g CO2 m-2 d-1, and the contribution of root respiration to total soil respiration from 38% to 76% and from 25% to 72% in Communities 1 and 2, respectively. During the growing season (May–September), soil respiration, shoot biomass, live root ...

  10. Isotopic Discrimination During Leaf Litter Decomposition

    Science.gov (United States)

    Ngao, J.; Rubino, M.

    2006-12-01

    Methods involving stable isotopes have been successfully applied since decades in various research fields. Tracing 13C natural abundance in ecosystem compartments greatly enhanced the understanding of the C fluxes in the plant-soil-atmosphere C exchanges when compartments present different C isotopic signatures (i.e. atmospheric CO2 vs photosynthetic leaves, C3 vs C4; etc.). However, the assumption that no isotopic discrimination occurs during respiration is commonly made in numbers of C isotope-based ecological studies. Furthermore, verifications of such assumption are sparse and not enough reliable. The aim of our study is to assess the potential isotopic discrimination that may occur during litter decomposition. Leaf litter from an Arbutus unedo (L.) stand (Tolfa, Italy) was incubated in 1L jars, under constant laboratory conditions (i.e. 25 ° C and 135% WC). During the entire incubation period, gravimetric mass loss, litter respiration rates and the isotopic composition of respired CO2 are monitored at regular intervals. Data from 7 months of incubation will be presented and discussed. After two months, the litter mass loss averaged 16% of initial dry mass. During the same time-period, the respiration rate decreased significantly by 58% of the initial respiration rate. Isotopic compositions of respired CO2 ranged between -27.95‰ and - 25.69‰. Mean values did not differ significantly among the sampling days, in spite of an apparent enrichment in 13C of respired CO2 with time. The significance of these isotopic enrichment will be determined at a longer time scale. They may reveal both/either a direct microbial discrimination during respiration processes and/or a use of different litter compounds as C source along time. Further chemical and compound-specific isotopic analysis of dry matter will be performed in order to clarify these hypotheses. This work is part of the "ALICE" project, funded by the European Union's Marie Curie Fellowship Actions that aims to

  11. Partitioning of ecosystem respiration in a beech forest

    DEFF Research Database (Denmark)

    Brændholt, Andreas; Ibrom, Andreas; Larsen, Klaus Steenberg

    2018-01-01

    Terrestrial ecosystem respiration (Reco) represents a major component of the global carbon cycle. It consists of many sub-components, such as aboveground plant respiration and belowground root and microbial respiration, each of which may respond differently to abiotic factors, and thus to global...... of Reco in a temperate beech forest at diel, seasonal and annual time scales. Reco was measured by eddy covariance while respiration rates from soil, tree stems and isolated coarse tree roots were measured bi-hourly by an automated closed-chamber system. Soil respiration (Rsoil) was measured in intact...... plots, and heterotrophic Rsoil was measured in trenched plots. Tree stem (Rstem) and coarse root (Rroot) respiration were measured by custom made closed-chambers. We found that the contribution of Rstem to total Reco varied across the year, by only accounting for 6% of Reco during winter and 16% during...

  12. Soil and Root Respiration Under Elevated CO2 Concentrations During Seedling Growth of Pinus sylvestris var. sylvestriformis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The objectives of this study were to investigate the effect of higher CO2 concentrations (500 and 700 μmol mol-1) in atmosphere on total soil respiration and the contribution of root respiration to total soil respiration during seedling growth of Pinus sylvestris var. sylvestriformis. During the four growing seasons (May-October) from 1999 to 2003, the seedlings were exposed to elevated concentrations of CO2 in open-top chambers. The total soil respiration and contribution of root respiration were measured using an LI-6400-09 soil CO2 flux chamber on June 15 and October 8, 2003. To separate root respiration from total soil respiration, three PVC cylinders were inserted approximately 30 cm deep into the soil in each chamber. There were marked diurnal changes in air and soil temperatures on June 15. Both the total soil respiration and the soil respiration without roots showed a strong diurnal pattern, increasing from before sunrise to about 14:00in the afternoon and then decreasing before the next sunrise. No increase in the mean total soil respiration and mean soil respiration with roots severed was observed under the elevated CO2 treatments on June 15, 2003, as compared to the open field and control chamber with ambient CO2. However, on October 8, 2003, the total soil respiration and soil respiration with roots severed in the open field were lower than those in the control and elevated CO2 chambers. The mean contribution of root respiration measured on June 15, 2003, ranged from 8.3% to 30.5% and on October 8, 2003,from 20.6% to 48.6%.

  13. Measurement methods and variability assessment of the Norway spruce total leaf area: Implications for remote sensing

    NARCIS (Netherlands)

    Homolova, L.; Lukes, P.; Malenovsky, Z.; Lhotakova, Z.; Kaplan, V.; Hanus, J.

    2013-01-01

    Estimation of total leaf area (LAT) is important to express biochemical properties in plant ecology and remote sensing studies. A measurement of LAT is easy in broadleaf species, but it remains challenging in coniferous canopies. We proposed a new geometrical model to estimate Norway spruce LAT and

  14. The ability of Abelmoschus manihot L. leaf extract in scavenging of free radical DPPH and total flavonoid determination

    Science.gov (United States)

    Sudewi, S.; Lolo, W. A.; Warongan, M.; Rifai, Y.; Rante, H.

    2017-11-01

    Abelmoschus manihot L. has reported to have flavonoids content. This study aims were to determine the ability of A. manihot extract in counteracting free radical DPPH and determine the content of total flavonoids. A. manihot leaf was taken from 2 regions in North Sulawesi, namely Tomohon and Kotamobagu. The maceration was carried out to extract the active compound in a 96% ethanol solvent. Free radical scavenging analysis was carried out by DPPH and determination of its total flavonoid in the extract was measured using spectrophotometri method. The results showed that A. manihot extract from Tomohon and Kotamobagu could counteract free radical of DPPH with value of free radical activity of 88.151 and 88.801 %, respectively. A. manihot leaf from Kotamobagu has higher total flavonoids content 61.763 mg/g compare to Tomohon 46.679 mg/g which presented as quercetin. A. manihot has antioxidant activity.

  15. Predicting tropical plant physiology from leaf and canopy spectroscopy.

    Science.gov (United States)

    Doughty, Christopher E; Asner, Gregory P; Martin, Roberta E

    2011-02-01

    A broad regional understanding of tropical forest leaf photosynthesis has long been a goal for tropical forest ecologists, but it has remained elusive due to difficult canopy access and high species diversity. Here we develop an empirical model to predict sunlit, light-saturated, tropical leaf photosynthesis using leaf and simulated canopy spectra. To develop this model, we used partial least squares (PLS) analysis on three tropical forest datasets (159 species), two in Hawaii and one at the biosphere 2 laboratory (B2L). For each species, we measured light-saturated photosynthesis (A), light and CO(2) saturated photosynthesis (A(max)), respiration (R), leaf transmittance and reflectance spectra (400-2,500 nm), leaf nitrogen, chlorophyll a and b, carotenoids, and leaf mass per area (LMA). The model best predicted A [r(2) = 0.74, root mean square error (RMSE) = 2.9 μmol m(-2) s(-1))] followed by R (r(2) = 0.48), and A(max) (r(2) = 0.47). We combined leaf reflectance and transmittance with a canopy radiative transfer model to simulate top-of-canopy reflectance and found that canopy spectra are a better predictor of A (RMSE = 2.5 ± 0.07 μmol m(-2) s(-1)) than are leaf spectra. The results indicate the potential for this technique to be used with high-fidelity imaging spectrometers to remotely sense tropical forest canopy photosynthesis.

  16. Parameterization of Leaf-Level Gas Exchange for Plant Functional Groups From Amazonian Seasonal Tropical Rain Forest

    Science.gov (United States)

    Domingues, T. F.; Berry, J. A.; Ometto, J. P.; Martinelli, L. A.; Ehleringer, J. R.

    2004-12-01

    Plant communities exert strong influence over the magnitude of carbon and water cycling through ecosystems by controlling photosynthetic gas exchange and respiratory processes. Leaf-level gas exchange fluxes result from a combination of physiological properties, such as carboxylation capacity, respiration rates and hydraulic conductivity, interacting with environmental drivers such as water and light availability, leaf-to-air vapor pressure deficit, and temperature. Carbon balance models concerned with ecosystem-scale responses have as a common feature the description of eco-physiological properties of vegetation. Here we focus on the parameterization of ecophysiological gas-exchange properties of plant functional groups from a pristine Amazonian seasonally dry tropical rain forest ecosystem (FLONA-Tapajós, Santarém, PA, Brazil). The parameters were specific leaf weight, leaf nitrogen content, leaf carbon isotope ratio, maximum photosynthetic assimilation rate, photosynthetic carboxylation capacity, dark respiration rates, and stomatal conductance to water vapor. Our plant functional groupings were lianas at the top of the canopy, trees at the top of the canopy, mid-canopy trees and undestory trees. Within the functional groups, we found no evidence that leaves acclimated to seasonal changes in precipitation. However, there were life-form dependent distinctions when a combination of parameters was included. Top-canopy lianas were statistically different from top-canopy trees for leaf carbon isotope ratio, maximum photosynthetic assimilation rate, and stomatal conductance to water vapor, suggesting that lianas are more conservative in the use of water, causing a stomatal limitation on photosynthetic assimilation. Top-canopy, mid canopy and understory groupings were distinct for specific leaf weight, leaf nitrogen content, leaf carbon isotope ratio, maximum photosynthetic assimilation rate, and photosynthetic carboxylation capacity. The recognition that plant

  17. Effect of inorganic nutrients on relative contributions of fungi and bacteria to carbon flow from submerged decomposing leaf litter

    Science.gov (United States)

    Vladislav Gulis; Keller Suberkropp

    2003-01-01

    The relative contributions of fungi and bacteria to carbon flow from submerged decaying plant litter at different levels of inorganic nutrients (N and P) were studied. We estimated leaf mass loss, fungal and bacterial biomass and production, and microbial respiration and constructed partial carbon budgets for red maple leaf disks precolonized in a stream and then...

  18. Litter Decomposition and Soil Respiration Responses to Fuel-Reduction Treatments in Piedmond Loblolly Pine Forests

    Science.gov (United States)

    Mac A. Callaham; Peter H. Anderson; Thomas A. Waldrop; Darren J. Lione; Victor B. Shelburne

    2004-01-01

    As part of the National Fire and Fire Surrogate Study, we measured the short-term effects of different fuel-management practices on leaf litter decomposition and soil respiration in loblolly pine stands on the upper Piedmont of South Carolina. These stands had been subjected to a factorial arrangement of experimental fuel-management treatments that included prescribed...

  19. ESTIMATING ROOT RESPIRATION IN SPRUCE AND BEECH: DECREASES IN SOIL RESPIRATION FOLLOWING GIRDLING

    Science.gov (United States)

    A study was undertaken to follow seasonal fluxes of CO2 from soil and to estimate the contribution of autotrophic (root + mycorrhizal) to total soil respiration (SR) in a mixed stand of European beech (Fagus sylvatica) and Norway spruce (Picea abies) near Freising, Germany. Matu...

  20. Does an elevated CO2 concentration decrease dark respiration in trees? Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Long, Stephen [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2003-12-31

    Averaged across many previous investigations, doubling the CO2 concentration ([CO2]) has frequently been reported to cause an instantaneous reduction of leaf dark respiration measured as CO2 efflux. No known mechanism accounts for this effect. While four recent studies have shown that the measurement of respiratory CO2 efflux is prone to experimental artifacts that could account for the reported response, papers published since the start of the current research continue to report an instantaneous depression of respiratory CO2 efflux by elevation of [CO2]. Here, these artifacts are avoided by use of a high-resolution dual channel oxygen analyzer within an open gas exchange system to measure respiratory 02 uptake in normal air. Leaf 02 uptake was determined in response to instantaneous elevation of [CO2] in nine contrasting species and to long-term elevation in seven species from four of the DOE-sponsored long-term elevated [CO2] field experiments. Over one thousand separate measurements of respiration failed to reveal any decrease in respiratory 02 uptake with an instantaneous increase in [CO2]. Respiration was found insensitive not only to doubling [CO2], but also to a five-fold increase and to decrease to zero.

  1. Effects of Ontogeny on δ13C of Plant- and Soil-Respired CO2 and on Respiratory Carbon Fractionation in C3 Herbaceous Species.

    Directory of Open Access Journals (Sweden)

    Yann Salmon

    Full Text Available Knowledge gaps regarding potential ontogeny and plant species identity effects on carbon isotope fractionation might lead to misinterpretations of carbon isotope composition (δ13C of respired CO2, a widely-used integrator of environmental conditions. In monospecific mesocosms grown under controlled conditions, the δ13C of C pools and fluxes and leaf ecophysiological parameters of seven herbaceous species belonging to three functional groups (crops, forage grasses and legumes were investigated at three ontogenetic stages of their vegetative cycle (young foliage, maximum growth rate, early senescence. Ontogeny-related changes in δ13C of leaf- and soil-respired CO2 and 13C/12C fractionation in respiration (ΔR were species-dependent and up to 7‰, a magnitude similar to that commonly measured in response to environmental factors. At plant and soil levels, changes in δ13C of respired CO2 and ΔR with ontogeny were related to changes in plant physiological status, likely through ontogeny-driven changes in the C sink to source strength ratio in the aboveground plant compartment. Our data further showed that lower ΔR values (i.e. respired CO2 relatively less depleted in 13C were observed with decreasing net assimilation. Our findings highlight the importance of accounting for ontogenetic stage and plant community composition in ecological studies using stable carbon isotopes.

  2. Effects of Ontogeny on δ13C of Plant- and Soil-Respired CO2 and on Respiratory Carbon Fractionation in C3 Herbaceous Species.

    Science.gov (United States)

    Salmon, Yann; Buchmann, Nina; Barnard, Romain L

    2016-01-01

    Knowledge gaps regarding potential ontogeny and plant species identity effects on carbon isotope fractionation might lead to misinterpretations of carbon isotope composition (δ13C) of respired CO2, a widely-used integrator of environmental conditions. In monospecific mesocosms grown under controlled conditions, the δ13C of C pools and fluxes and leaf ecophysiological parameters of seven herbaceous species belonging to three functional groups (crops, forage grasses and legumes) were investigated at three ontogenetic stages of their vegetative cycle (young foliage, maximum growth rate, early senescence). Ontogeny-related changes in δ13C of leaf- and soil-respired CO2 and 13C/12C fractionation in respiration (ΔR) were species-dependent and up to 7‰, a magnitude similar to that commonly measured in response to environmental factors. At plant and soil levels, changes in δ13C of respired CO2 and ΔR with ontogeny were related to changes in plant physiological status, likely through ontogeny-driven changes in the C sink to source strength ratio in the aboveground plant compartment. Our data further showed that lower ΔR values (i.e. respired CO2 relatively less depleted in 13C) were observed with decreasing net assimilation. Our findings highlight the importance of accounting for ontogenetic stage and plant community composition in ecological studies using stable carbon isotopes.

  3. Underwater photosynthesis and respiration in leaves of submerged wetland plants: gas films improve CO2 and O2 exchange

    DEFF Research Database (Denmark)

    Colmer, Timothy David; Pedersen, Ole

    2007-01-01

    (N) was enhanced up to sixfold. Gas films on submerged leaves enable continued gas exchange via stomata and thus bypassing of cuticle resistance, enhancing exchange of O(2) and CO(2) with the surrounding water, and therefore underwater P(N) and respiration.......Many wetland plants have gas films on submerged leaf surfaces. We tested the hypotheses that leaf gas films enhance CO(2) uptake for net photosynthesis (P(N)) during light periods, and enhance O(2) uptake for respiration during dark periods. Leaves of four wetland species that form gas films......, and two species that do not, were used. Gas films were also experimentally removed by brushing with 0.05% (v/v) Triton X. Net O(2) production in light, or O(2) consumption in darkness, was measured at various CO(2) and O(2) concentrations. When gas films were removed, O(2) uptake in darkness was already...

  4. Misconception of biology education student of teacher training and education of Sriwijaya University to the concept of photosynthesis and respiration

    Science.gov (United States)

    Susanti, Rahmi

    2018-05-01

    This study aimed to gain an overview of misconceptions on the concept of photosynthesis and respiration. The study involved 58 students from Biology Education of Sriwijaya University. Collecting data used written test of 16 questions, which are 10 questions of multiple choice and 6 of choice with reason. The results showed that:photosynthesis occurs continuously (37.9%), energy used for photosynthesis are light and heat energy (34.5%), plants take CO2to respiration (47%), plants carry on respiration in the absence of light for photosynthesis (22.4%), respiration in plants occurs only in leaf cells (76.4%), and only animals that take O2 of photosynthesis to respiration (68.9%). The conclusion: 1) on the concept of photosynthesis is still prevailing misconceptions about the concept of the place and time of the occurrence of photosynthesis in plants, the role of the sun in photosynthesis, energy is required in the form of photosynthesis, and the role of photosynthesis for the plant. 2) on the concept of respiration is still prevailing misconceptions about the place of the respiration in plants, gas necessary for respiration of plants, and the plants perform respiration time, as well as the cycle of CO2 and O2 that occurs in nature.

  5. Abiotic and biotic determinants of leaf carbon exchange capacity from tropical to high boreal biomes

    Science.gov (United States)

    Smith, N. G.; Dukes, J. S.

    2016-12-01

    Photosynthesis and respiration on land represent the two largest fluxes of carbon dioxide between the atmosphere and the Earth's surface. As such, the Earth System Models that are used to project climate change are high sensitive to these processes. Studies have found that much of this uncertainty is due to the formulation and parameterization of plant photosynthetic and respiratory capacity. Here, we quantified the abiotic and biotic factors that determine photosynthetic and respiratory capacity at large spatial scales. Specifically, we measured the maximum rate of Rubisco carboxylation (Vcmax), the maximum rate of Ribulose-1,5-bisphosphate regeneration (Jmax), and leaf dark respiration (Rd) in >600 individuals of 98 plant species from the tropical to high boreal biomes of Northern and Central America. We also measured a bevy of covariates including plant functional type, leaf nitrogen content, short- and long-term climate, leaf water potential, plant size, and leaf mass per area. We found that plant functional type and leaf nitrogen content were the primary determinants of Vcmax, Jmax, and Rd. Mean annual temperature and mean annual precipitation were not significant predictors of these rates. However, short-term climatic variables, specifically soil moisture and air temperature over the previous 25 days, were significant predictors and indicated that heat and soil moisture deficits combine to reduce photosynthetic capacity and increase respiratory capacity. Finally, these data were used as a model benchmarking tool for the Community Land Model version 4.5 (CLM 4.5). The benchmarking analyses determined errors in the leaf nitrogen allocation scheme of CLM 4.5. Under high leaf nitrogen levels within a plant type the model overestimated Vcmax and Jmax. This result suggested that plants were altering their nitrogen allocation patterns when leaf nitrogen levels were high, an effect that was not being captured by the model. These data, taken with models in mind

  6. Leaf physiological responses of mature Norway Spruce trees exposed to elevated carbon dioxide and temperature

    Science.gov (United States)

    Lamba, Shubhangi; Uddling, Johan; Räntfors, Mats; Hall, Marianne; Wallin, Göran

    2014-05-01

    Leaf photosynthesis, respiration and stomatal conductance exert strong control over the exchange of carbon, water and energy between the terrestrial biosphere and the atmosphere. As such, leaf physiological responses to rising atmospheric CO2 concentration ([CO2]) and temperature have important implications for the global carbon cycle and rate of ongoing global warming, as well as for local and regional hydrology and evaporative cooling. It is therefore critical to improve the understanding of plant physiological responses to elevated [CO2] and temperature, in particular for boreal and tropical ecosystems. In order to do so, we examined physiological responses of mature boreal Norway spruce trees (ca 40-years old) exposed to elevated [CO2] and temperature inside whole-tree chambers at Flakaliden research site, Northern Sweden. The trees were exposed to a factorial combination of two levels of [CO2] (ambient and doubled) and temperature (ambient and +2.8 degree C in summer and +5.6 degree C in winter). Three replicates in each of the four treatments were used. It was found that photosynthesis was increased considerably in elevated [CO2], but was not affected by the warming treatment. The maximum rate of photosynthetic carboxylation was reduced in the combined elevated [CO2] and elevated temperature treatment, but not in single factor treatments. Elevated [CO2] also strongly increased the base rate of respiration and to a lesser extent reduced the temperature sensitivity (Q10 value) of respiration; responses which may be important for the carbon balance of these trees which have a large proportion of shaded foliage. Stomatal conductance at a given VPD was reduced by elevated temperature treatment, to a degree that mostly offset the higher vapour pressure deficit in warmed air with respect to transpiration. Elevated [CO2] did not affect stomatal conductance, and thus increased the ratio of leaf internal to external [CO2]. These results indicate that the large elevated

  7. Association Mapping of Total Carotenoids in Diverse Soybean Genotypes Based on Leaf Extracts and High-Throughput Canopy Spectral Reflectance Measurements.

    Directory of Open Access Journals (Sweden)

    Arun Prabhu Dhanapal

    Full Text Available Carotenoids are organic pigments that are produced predominantly by photosynthetic organisms and provide antioxidant activity to a wide variety of plants, animals, bacteria, and fungi. The carotenoid biosynthetic pathway is highly conserved in plants and occurs mostly in chromoplasts and chloroplasts. Leaf carotenoids play important photoprotective roles and targeted selection for leaf carotenoids may offer avenues to improve abiotic stress tolerance. A collection of 332 soybean [Glycine max (L. Merr.] genotypes was grown in two years and total leaf carotenoid content was determined using three different methods. The first method was based on extraction and spectrophotometric determination of carotenoid content (eCaro in leaf tissue, whereas the other two methods were derived from high-throughput canopy spectral reflectance measurements using wavelet transformed reflectance spectra (tCaro and a spectral reflectance index (iCaro. An association mapping approach was employed using 31,253 single nucleotide polymorphisms (SNPs to identify SNPs associated with total carotenoid content using a mixed linear model based on data from two growing seasons. A total of 28 SNPs showed a significant association with total carotenoid content in at least one of the three approaches. These 28 SNPs likely tagged 14 putative loci for carotenoid content. Six putative loci were identified using eCaro, five loci with tCaro, and nine loci with iCaro. Three of these putative loci were detected by all three carotenoid determination methods. All but four putative loci were located near a known carotenoid-related gene. These results showed that carotenoid markers can be identified in soybean using extract-based as well as by high-throughput canopy spectral reflectance-based approaches, demonstrating the utility of field-based canopy spectral reflectance phenotypes for association mapping.

  8. Seasonality and Interannual Variability of Carbon Uptake and Respiration in a California Oak Savanna

    Science.gov (United States)

    Ma, S.; Baldocchi, D.; Xu, L.

    2005-12-01

    Estimating terrestrial carbon sink with large-scale modeling research requires understanding the physiological and ecological processes associated with the carbon uptake and respiration of ecosystems and their variability in seasons and years. This study was conducted in an oak/grass savanna ecosystem in California, USA. The savanna ecosystem consists of blue oak trees ( Quercus douglasii) in the overstory and annual C3 grasses in the understory. Fluxes of CO2 were measured above the canopy (overstory) and the grasses (understory) from 2001 to 2005 with two eddy covariance systems. Under typical Mediterranean Climate, net ecosystem exchange of CO2 (NEE), ecosystem respiration (Reco), and gross primary production (GPP) in this savanna ecosystem had a distinctive dry-wet seasonal pattern. Leaf area index, leaf nitrogen concentration, and leaf carbon stable isotope discrimination reflected the responses of leaf to the seasonality and interannual variability. Light- use efficiency, the ratio of GPP to absorbed photosynthetically active radiation (aPAR), was not consistent within a year or from year to year, indicating that photosynthesis process was constrained with low temperature during the beginning of the wet season and limited by precipitation during the summer drought. Annual NEE, Reco, and GPP above the canopy varied significantly between years, varying from -108 - 133 gC m-2, 780 - 988 gC m-2, and 646 - 963 gC m-2, respectively. The difference of interannual Reco was 1.2 times of that of interannual GPP. There was a tight relationship between annual NEE and the precipitation during the period with daily mean temperature varying between 10 - 20°C, equivalent to precipitation during March and April. The longer the period lasted, the higher carbon uptake occurred. Estimated annual NEE from 1949 - 2005 in the savanna ecosystem varied between ~-400 - 200 gC m-2.

  9. Effect of nitrogen on the seasonal course of growth and maintenance respiration in stems of Norway spruce trees.

    Science.gov (United States)

    Stockfors, Jan; Linder, Sune

    1998-03-01

    To determine effects of stem nitrogen concentration ([N]) on the seasonal course of respiration, rates of stem respiration of ten control and ten irrigated-fertilized (IL), 30-year-old Norway spruce trees (Picea abies (L.) Karst.), growing in northern Sweden, were measured on seven occasions from June 1993 to April 1994. To explore sources of seasonal variation and mechanisms of fertilization effects on respiration, we separated total respiration into growth and maintenance respiration for both xylem and phloem bark. Stem respiration increased in response to the IL treatment and was positively correlated with growth rate, volume of living cells and stem nitrogen content. However, no significant effect of IL treatment or [N] in the living cells was found for respiration per unit volume of live cells. Total stem respiration during the growing season (June to September) was estimated to be 16.7 and 29.7 mol CO(2) m(-2) for control and IL-treated trees, respectively. Respiration during the growing season accounted for approximately 64% of total annual respiration. Depending on the method, estimated growth respiration varied between 40 and 60% of total respiration during the growing season. Between 75 and 80% of the live cell volume in the stems was in the phloem, and phloem maintenance accounted for about 70% of maintenance respiration. Because most of the living cells were found in the phloem, and the living xylem cells were concentrated in the outer growth rings, we concluded that the best base for expressing rates of stem growth and maintenance respiration in young Norway spruce trees is stem surface area.

  10. Measurement of gross photosynthesis, respiration in the light, and mesophyll conductance using H218O labeling.

    Science.gov (United States)

    Gauthier, Paul Pg; Battle, Mark O; Griffin, Kevin L; Bender, Michael L

    2018-03-27

    A fundamental challenge in plant physiology is independently determining the rates of gross O2 production by photosynthesis and O2 consumption by respiration, photorespiration, and other processes. Previous studies on isolated chloroplasts or leaves have separately constrained net and gross O2 production (NOP and GOP, respectively) by labeling ambient O2 with 18O while leaf water was unlabeled. Here, we describe a method to accurately measure GOP and NOP of whole detached leaves in a cuvette as a routine gas exchange measurement. The petiole is immersed in water enriched to a δ18O of ~9,000‰, and leaf water is labeled through the transpiration stream. Photosynthesis transfers 18O from H2O to O2. GOP is calculated from the increase in δ18O of O2 as air passes through the cuvette. NOP is determined from the increase in O2/N2. Both terms are measured by isotope ratio mass spectrometry. CO2 assimilation and other standard gas exchange parameters are also measured. Reproducible measurements are made on a single leaf for more than 15 hours. We used this method to measure the light response curve of NOP and GOP in Phaseolus vulgaris at 21% and 2% O2. We then used these data to examine the O2/CO2 ratio of net photosynthesis, the light response curve of mesophyll conductance, and the apparent inhibition of respiration in the light (Kok effect) at both oxygen levels. The results are discussed in the context of evaluating the technique as a tool to study and understand leaf physiological traits. {copyright, serif} 2018 American Society of Plant Biologists. All rights reserved.

  11. Leaf habit and woodiness regulate different leaf economy traits at a given nutrient supply.

    Science.gov (United States)

    Ordoñez, Jenny C; van Bodegom, Peter M; Witte, Jan-Philip M; Bartholomeus, Ruud P; van Dobben, Han F; Aerts, Rien

    2010-11-01

    The large variation in the relationships between environmental factors and plant traits observed in natural communities exemplifies the alternative solutions that plants have developed in response to the same environmental limitations. Qualitative attributes, such as growth form, woodiness, and leaf habit can be used to approximate these alternative solutions. Here, we quantified the extent to which these attributes affect leaf trait values at a given resource supply level, using measured plant traits from 105 different species (254 observations) distributed across 50 sites in mesic to wet plant communities in The Netherlands. For each site, soil total N, soil total P, and water supply estimates were obtained by field measurements and modeling. Effects of growth forms, woodiness, and leaf habit on relations between leaf traits (SLA, specific leaf area; LNC, leaf nitrogen concentration; and LPC, leaf phosphorus concentration) vs. nutrient and water supply were quantified using maximum-likelihood methods and Bonferroni post hoc tests. The qualitative attributes explained 8-23% of the variance within sites in leaf traits vs. soil fertility relationships, and therefore they can potentially be used to make better predictions of global patterns of leaf traits in relation to nutrient supply. However, at a given soil fertility, the strength of the effect of each qualitative attribute was not the same for all leaf traits. These differences may imply a differential regulation of the leaf economy traits at a given nutrient supply, in which SLA and LPC seem to be regulated in accordance to changes in plant size and architecture while LNC seems to be primarily regulated at the leaf level by factors related to leaf longevity.

  12. Phytochemical screening, total phenolics and antioxidant activities of bark and leaf extracts of Goniothalamus velutinus (Airy Shaw from Brunei Darussalam

    Directory of Open Access Journals (Sweden)

    Erum Iqbal

    2015-07-01

    Full Text Available Goniothalamus velutinus Airy Shaw belongs to the family Annonaceae which is known to have anticancer, antitumor and many other bioactivities. Natives of Sabah and Sarawak use root decoction of G. velutinus for the treatment of headache and food poisoning while the bark was used as a mosquito repellent. Bark and leaf extracts of this plant, obtained from Brunei Darussalam, were tested for phytochemical and antioxidant activities. Phytochemical screening of plant extracts revealed the presence of alkaloids, steroids, terpenoids and cardiac glycosides. Quantitative determination of total phenolics, total flavonoids, and various in vitro antioxidant activities (DPPH, ABTS and FRAP of methanolic extract was carried out using colorimetric methods. The total phenolic content, expressed as mg of gallic acid equivalent (GAE per gram of extract, was found to be 68 mg GAE/g and 78 mg GAE/g for bark and leaves respectively. The radical scavenging activity measurement, expressed in terms of EC50 (effective concentration of extract in μg/mL that reduces DPPH absorbance to 50% as compared to negative control, for leaf and bark extracts was found to be 155 μg/mL and 204 μg/mL respectively. Standards trolox and ascorbic acid show EC50 value of 5 μg/mL and 4 μg/mL respectively. Trolox equivalent antioxidant capacity (TEAC was measured using the ABTS and FRAP method. Result for bark and leaf extracts was 79 mg and 106 mg trolox equivalent (TE/g respectively for the ABTS method. For FRAP assay, results for bark and leaf extracts were 80 and 89 mg TE/g respectively.

  13. Soil respiration at mean annual temperature predicts annual total across vegetation types and biomes

    Directory of Open Access Journals (Sweden)

    M. Bahn

    2010-07-01

    Full Text Available Soil respiration (SR constitutes the largest flux of CO2 from terrestrial ecosystems to the atmosphere. However, there still exist considerable uncertainties as to its actual magnitude, as well as its spatial and interannual variability. Based on a reanalysis and synthesis of 80 site-years for 57 forests, plantations, savannas, shrublands and grasslands from boreal to tropical climates we present evidence that total annual SR is closely related to SR at mean annual soil temperature (SRMAT, irrespective of the type of ecosystem and biome. This is theoretically expected for non water-limited ecosystems within most of the globally occurring range of annual temperature variability and sensitivity (Q10. We further show that for seasonally dry sites where annual precipitation (P is lower than potential evapotranspiration (PET, annual SR can be predicted from wet season SRMAT corrected for a factor related to P/PET. Our finding indicates that it can be sufficient to measure SRMAT for obtaining a well constrained estimate of its annual total. This should substantially increase our capacity for assessing the spatial distribution of soil CO2 emissions across ecosystems, landscapes and regions, and thereby contribute to improving the spatial resolution of a major component of the global carbon cycle.

  14. Gastrocnemius mitochondrial respiration: are there any differences between men and women?

    Science.gov (United States)

    Thompson, Jonathan R; Swanson, Stanley A; Casale, George P; Johanning, Jason M; Papoutsi, Evlampia; Koutakis, Panagiotis; Miserlis, Dimitrios; Zhu, Zhen; Pipinos, Iraklis I

    2013-11-01

    Work on human and mouse skeletal muscle by our group and others has demonstrated that aging and age-related degenerative diseases are associated with mitochondrial dysfunction, which may be more prevalent in males. There have been, however, no studies that specifically examine the influence of male or female sex on human skeletal muscle mitochondrial respiration. The purpose of this study was to compare mitochondrial respiration in the gastrocnemius of adult men and women. Gastrocnemius muscle was obtained from male (n = 19) and female (n = 11) human subjects with healthy lower-extremity musculoskeletal and arterial systems and normal ambulatory function. All patients were undergoing operations for the treatment of varicose veins in their legs. Mitochondrial respiration was determined with a Clark electrode in an oxygraph cell containing saponin-skinned muscle bundles. Complex I-, II-, III-, and IV-dependent respiration was measured individually and normalized to muscle weight, total protein content, and citrate synthase (CS, index of mitochondrial content). Male and female patients had no evidence of musculoskeletal or arterial disease and did not differ with regard to age, race, body mass index, or other clinical characteristics. Complex I-, II-, III-, and IV-dependent respiration normalized to muscle weight, total protein content, and CS did not statistically differ for males compared with females. Our study evaluates, for the first time, gastrocnemius mitochondrial respiration of adult men and women who have healthy musculoskeletal and arterial systems and normal ambulatory function. Our data demonstrate there are no differences in the respiration of gastrocnemius mitochondria between men and women. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Forest thinning and soil respiration in a ponderosa pine plantation in the Sierra Nevada.

    Science.gov (United States)

    Tang, Jianwu; Qi, Ye; Xu, Ming; Misson, Laurent; Goldstein, Allen H

    2005-01-01

    Soil respiration is controlled by soil temperature, soil water, fine roots, microbial activity, and soil physical and chemical properties. Forest thinning changes soil temperature, soil water content, and root density and activity, and thus changes soil respiration. We measured soil respiration monthly and soil temperature and volumetric soil water continuously in a young ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws.) plantation in the Sierra Nevada Mountains in California from June 1998 to May 2000 (before a thinning that removed 30% of the biomass), and from May to December 2001 (after thinning). Thinning increased the spatial homogeneity of soil temperature and respiration. We conducted a multivariate analysis with two independent variables of soil temperature and water and a categorical variable representing the thinning event to simulate soil respiration and assess the effect of thinning. Thinning did not change the sensitivity of soil respiration to temperature or to water, but decreased total soil respiration by 13% at a given temperature and water content. This decrease in soil respiration was likely associated with the decrease in root density after thinning. With a model driven by continuous soil temperature and water time series, we estimated that total soil respiration was 948, 949 and 831 g C m(-2) year(-1) in the years 1999, 2000 and 2001, respectively. Although thinning reduced soil respiration at a given temperature and water content, because of natural climate variability and the thinning effect on soil temperature and water, actual cumulative soil respiration showed no clear trend following thinning. We conclude that the effect of forest thinning on soil respiration is the combined result of a decrease in root respiration, an increase in soil organic matter, and changes in soil temperature and water due to both thinning and interannual climate variability.

  16. Soil Respiration under Different Land Uses in Eastern China

    Science.gov (United States)

    Fan, Li-Chao; Yang, Ming-Zhen; Han, Wen-Yan

    2015-01-01

    Land-use change has a crucial influence on soil respiration, which further affects soil nutrient availability and carbon stock. We monitored soil respiration rates under different land-use types (tea gardens with three production levels, adjacent woodland, and a vegetable field) in Eastern China at weekly intervals over a year using the dynamic closed chamber method. The relationship between soil respiration and environmental factors was also evaluated. The soil respiration rate exhibited a remarkable single peak that was highest in July/August and lowest in January. The annual cumulative respiration flux increased by 25.6% and 20.9% in the tea garden with high production (HP) and the vegetable field (VF), respectively, relative to woodland (WL). However, no significant differences were observed between tea gardens with medium production (MP), low production (LP), WL, and VF. Soil respiration rates were significantly and positively correlated with organic carbon, total nitrogen, and available phosphorous content. Each site displayed a significant exponential relationship between soil respiration and soil temperature measured at 5 cm depth, which explained 84–98% of the variation in soil respiration. The model with a combination of soil temperature and moisture was better at predicting the temporal variation of soil respiration rate than the single temperature model for all sites. Q10 was 2.40, 2.00, and 1.86–1.98 for VF, WL, and tea gardens, respectively, indicating that converting WL to VF increased and converting to tea gardens decreased the sensitivity of soil respiration to temperature. The equation of the multiple linear regression showed that identical factors, including soil organic carbon (SOC), soil water content (SWC), pH, and water soluble aluminum (WSAl), drove the changes in soil respiration and Q10 after conversion of land use. Temporal variations of soil respiration were mainly controlled by soil temperature, whereas spatial variations were

  17. Application of edible coating from cassava peel – bay leaf on avocado

    Science.gov (United States)

    Handayani, M. N.; Karlina, S.; Sugiarti, Y.; Cakrawati, D.

    2018-05-01

    Avocados have a fairly short shelf life and are included in climacteric fruits. Edible coating application is one alternative to maintain the shelf life of avocado. Cassava peel starch is potential to be used as raw material for edible coating making. Addition of bay leaf extract containing antioxidants can increase the functional value of edible coating. The purpose of this study is to know the shrinkage of weight, acid number, color change and respiration rate of avocado coated with edible coating from cassava peel starch with an addition of bay leaf extract. The study consisted of making cassava peel starch, bay leaf extraction, edible coating making, edible coating application on avocado, and analysis of avocado characteristics during storage at room temperature. The results showed that addition of bay leaf extract on cassava peel starch edible coating applied to avocado, an effect on characteristics of avocado. Avocado applied edible coating and stored at room temperatures had lower weight loss than avocado without edible coating, lower acid number, tend to be more able to maintain color rather than avocado without edible coating.

  18. Temperature response of soil respiration largely unaltered with experimental warming

    DEFF Research Database (Denmark)

    Carey, Joanna C; Tang, Jianwu; Templer, Pamela H

    2016-01-01

    The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific...... attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies......, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation...

  19. Choosing the right respirator

    International Nuclear Information System (INIS)

    Bidwell, J.

    1997-01-01

    Selecting respirators to help protect workers from airborne contaminants can be a confusing process. The consequences of selecting the incorrect respirator can be intimidating, and worker safety and health may be dramatically and irreparably affected if an inappropriate respirator is chosen. When used in the workplace, a formal respiratory protection program must be established covering the basic requirements outlined in the OSHA Respiratory Protection Standard (29 CFR 1910.134). Education and training must be properly emphasized and conducted periodically. Maintenance, cleaning, and storage programs must be established and routinely followed for reusable respirators. The process of establishing a respiratory protection program can be broken down into four basic steps: Identify respiratory hazards and concentrations; understand the contaminants effects on workers' health; select appropriate respiratory protection; and train in proper respirator use and maintenance. These four steps are the foundation for establishing a basic respirator protection program. Be sure to consult state and federal OSHA requirements to ensure that the program complies. Leading industrial respirator manufacturers should be able to assist with on-site training and education in this four-step process, in addition to helping employers train their workers and conduct respirator fit testing

  20. [Dynamic changes in soil respiration components and their regulating factors in the Moso bamboo plantation in subtropical China].

    Science.gov (United States)

    Yang, Wen-jia; Li, Yong-fu; Jiang, Pei-kun; Zhou, Guo-mo; Liu, Juan

    2015-10-01

    Dynamic changes (from April 2013 to March 2014) in soil respiration components were investigated by Li-8100 in the Moso bamboo plantation in Lin' an City, Zhejiang Province. Results showed that the average annual values for the soil total respiration rate, heterotrophic respiration rate, and autotrophic respiration rate in the Moso bamboo plantation were 2.93, 1.92 and 1.01 imol CO2 . m-2 . s-1, respectively. The soil respiration rate and its components exhibited strongly a seasonal dynamic pattern. The maximum appeared in July 2013, and the minimum appeared in January 2014. The annual cumulative CO2 emissions through soil respiration, heterotrophic respiration, and autotrophic respiration were 37.25, 24.61 and 12.64 t CO2 . hm-2 . a-1, respectively. The soil respiration and its components showed a close relation with soil temperature of 5 cm depth, and the corresponding Q10, values at 5 cm depth were 2.05, 1.95 and 2.34, respectively. Both the soil respiration and heterotrophic respiration were correlated to soil water soluble organic C (WSOC) content, but no significant relationship between autotrophic respiration and WSOC was observed. There were no significant relationships between soil respiration components and soil moisture content or microbial biomass C. The seasonal changes in soil respiration components in the Moso bamboo plantation were predominantly controlled by the soil temperature, and the soil WSOC content was an important environmental factor controlling total soil respiration and soil heterotrophic respiration.

  1. Genotype differences in 13C discrimination between atmosphere and leaf matter match differences in transpiration efficiency at leaf and whole-plant levels in hybrid Populus deltoides x nigra.

    Science.gov (United States)

    Rasheed, Fahad; Dreyer, Erwin; Richard, Béatrice; Brignolas, Franck; Montpied, Pierre; Le Thiec, Didier

    2013-01-01

    (13) C discrimination between atmosphere and bulk leaf matter (Δ(13) C(lb) ) is frequently used as a proxy for transpiration efficiency (TE). Nevertheless, its relevance is challenged due to: (1) potential deviations from the theoretical discrimination model, and (2) complex time integration and upscaling from leaf to whole plant. Six hybrid genotypes of Populus deltoides×nigra genotypes were grown in climate chambers and tested for whole-plant TE (i.e. accumulated biomass/water transpired). Net CO(2) assimilation rates (A) and stomatal conductance (g(s) ) were recorded in parallel to: (1) (13) C in leaf bulk material (δ(13) C(lb) ) and in soluble sugars (δ(13) C(ss) ) and (2) (18) O in leaf water and bulk leaf material. Genotypic means of δ(13) C(lb) and δ(13) C(ss) were tightly correlated. Discrimination between atmosphere and soluble sugars was correlated with daily intrinsic TE at leaf level (daily mean A/g(s) ), and with whole-plant TE. Finally, g(s) was positively correlated to (18) O enrichment of bulk matter or water of leaves at individual level, but not at genotype level. We conclude that Δ(13) C(lb) captures efficiently the genetic variability of whole-plant TE in poplar. Nevertheless, scaling from leaf level to whole-plant TE requires to take into account water losses and respiration independent of photosynthesis, which remain poorly documented. © 2012 Blackwell Publishing Ltd.

  2. Temperature response of soil respiration largely unaltered with experimental warming

    Science.gov (United States)

    Carey, Joanna C.; Tang, Jianwu; Templer, Pamela H.; Kroeger, Kevin D.; Crowther, Thomas W.; Burton, Andrew J.; Dukes, Jeffrey S.; Emmett, Bridget; Frey, Serita D.; Heskel, Mary A.; Jiang, Lifen; Machmuller, Megan B.; Mohan, Jacqueline; Panetta, Anne Marie; Reich, Peter B.; Reinsch, Sabine; Wang, Xin; Allison, Steven D.; Bamminger, Chris; Bridgham, Scott; Collins, Scott L.; de Dato, Giovanbattista; Eddy, William C.; Enquist, Brian J.; Estiarte, Marc; Harte, John; Henderson, Amanda; Johnson, Bart R.; Steenberg Larsen, Klaus; Luo, Yiqi; Marhan, Sven; Melillo, Jerry M.; Penuelas, Josep; Pfeifer-Meister, Laurel; Poll, Christian; Rastetter, Edward B.; Reinmann, Andrew B.; Reynolds, Lorien L.; Schmidt, Inger K.; Shaver, Gaius R.; Strong, Aaron L.; Suseela, Vidya; Tietema, Albert

    2016-01-01

    The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation of soil respiration to experimental warming in several major biome types, contrary to the results from multiple single-site studies. Moreover, across all nondesert biomes, respiration rates with and without experimental warming follow a Gaussian response, increasing with soil temperature up to a threshold of ∼25 °C, above which respiration rates decrease with further increases in temperature. This consistent decrease in temperature sensitivity at higher temperatures demonstrates that rising global temperatures may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic warming.

  3. Oxygen respiration rates of benthic foraminifera as measured with oxygen microsensors

    DEFF Research Database (Denmark)

    Geslin, E.; Risgaard-Petersen, N.; Lombard, Fabien

    2011-01-01

    of the foraminiferal specimens. The results show a wide range of oxygen respiration rates for the different species (from 0.09 to 5.27 nl cell−1 h−1) and a clear correlation with foraminiferal biovolume showed by the power law relationship: R = 3.98 10−3 BioVol0.88 where the oxygen respiration rate (R) is expressed......Oxygen respiration rates of benthic foraminifera are still badly known, mainly because they are difficult to measure. Oxygen respiration rates of seventeen species of benthic foraminifera were measured using microelectrodes and calculated on the basis of the oxygen fluxes measured in the vicinity...... groups (nematodes, copepods, ostracods, ciliates and flagellates) suggests that benthic foraminifera have a lower oxygen respiration rates per unit biovolume. The total contribution of benthic foraminifera to the aerobic mineralisation of organic matter is estimated for the studied areas. The results...

  4. Evaluation of 14C abundance in soil respiration using accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Koarashi, Jun; Iida, Takao; Moriizumi, Jun; Asano, Tomohiro

    2004-01-01

    To clarify the behavior of 14 C in terrestrial ecosystems, 14 C abundance in soil respiration was evaluated in an urban forest with a new method involving a closed chamber technique and 14 C measurement by accelerator mass spectrometry (AMS). Soil respiration had a higher Δ 14 C than the contemporary atmosphere. This indicates that a significant portion of soil respiration is derived from the decomposition of soil organic matter enriched in 14 C by atmospheric nuclear weapons tests, with a notable time lag between atmospheric 14 C addition and re-emission from soil. On the other hand, δ 14 C in soil respiration demonstrated that 14 C abundance ratio itself in soil-respired CO 2 is not always high compared with that in atmospheric CO 2 because of the isotope fractionation during plant photosynthesis and microbial decomposition of soil organic matter. The Δ 14 C in soil respiration was slightly lower in August than in March, suggesting a relatively high contribution of plant root respiration and decomposition of newly accumulated and/or 14 C-depleted soil organic matter to the total soil respiration in August

  5. Global spatiotemporal distribution of soil respiration modeled using a global database

    Science.gov (United States)

    Hashimoto, S.; Carvalhais, N.; Ito, A.; Migliavacca, M.; Nishina, K.; Reichstein, M.

    2015-07-01

    The flux of carbon dioxide from the soil to the atmosphere (soil respiration) is one of the major fluxes in the global carbon cycle. At present, the accumulated field observation data cover a wide range of geographical locations and climate conditions. However, there are still large uncertainties in the magnitude and spatiotemporal variation of global soil respiration. Using a global soil respiration data set, we developed a climate-driven model of soil respiration by modifying and updating Raich's model, and the global spatiotemporal distribution of soil respiration was examined using this model. The model was applied at a spatial resolution of 0.5°and a monthly time step. Soil respiration was divided into the heterotrophic and autotrophic components of respiration using an empirical model. The estimated mean annual global soil respiration was 91 Pg C yr-1 (between 1965 and 2012; Monte Carlo 95 % confidence interval: 87-95 Pg C yr-1) and increased at the rate of 0.09 Pg C yr-2. The contribution of soil respiration from boreal regions to the total increase in global soil respiration was on the same order of magnitude as that of tropical and temperate regions, despite a lower absolute magnitude of soil respiration in boreal regions. The estimated annual global heterotrophic respiration and global autotrophic respiration were 51 and 40 Pg C yr-1, respectively. The global soil respiration responded to the increase in air temperature at the rate of 3.3 Pg C yr-1 °C-1, and Q10 = 1.4. Our study scaled up observed soil respiration values from field measurements to estimate global soil respiration and provide a data-oriented estimate of global soil respiration. The estimates are based on a semi-empirical model parameterized with over one thousand data points. Our analysis indicates that the climate controls on soil respiration may translate into an increasing trend in global soil respiration and our analysis emphasizes the relevance of the soil carbon flux from soil to

  6. Developmental light level affects growth, morphology, and leaf physiology of young carambola trees

    International Nuclear Information System (INIS)

    Marler, T.E.; Schaffer, B.; Crane, J.H.

    1994-01-01

    Growth and leaf physiology responses of container-grown 'Arkin' carambola (Averrhoa carambola L.) trees to long-term exposure of approximately 25%, approximately 50%, or 100% sunlight were studied in four experiments in Guam and Florida. Shading increased rachis length and leaflet area, and decreased leaflet thickness. Shaded trees also had a more horizontal branch orientation. Shading reduced dark respiration (Rd) and light compensation and saturation points but increased chlorophyll concentration and N-use efficiency. Light-saturated net CO2 assimilation (A) was not affected by developmental light level. Trees in full sun had smaller total leaf area, canopy diameter, and shoot:root ratio and exhibited leaflet movement to avoid direct solar radiation. Also, trees grown in 100% sunlight had a more vertical branch orientation and greater stomatal density than shaded trees. The ratio of variable to maximum fluorescence (Fv/Fm) declined during midday in 100% sunlight trees. This pattern was accompanied by a midday suppression of A in 100% sunlight-grown trees in Guam. 'Arkin' carambola trees exposed to approximately 25%, approximately 50%, or 100% sunlight for up to 39 weeks exhibited physiological and morphological adaptations that resulted in similar growth. These results indicate that carambola efficiently adapts to different developmental light intensities

  7. [Effects of Tillage on Soil Respiration and Root Respiration Under Rain-Fed Summer Corn Field].

    Science.gov (United States)

    Lu, Xing-li; Liao, Yun-cheng

    2015-06-01

    To explore the effects of different tillage systems on soil respiration and root respiration under rain-fed condition. Based on a short-term experiment, this paper investigated soil respiration in summer corn growth season under four tillage treatments including subsoiling tillage (ST), no tillage (NT), rotary tillage (RT) and moldboard plow tillage (CT). The contribution of root respiration using root exclusion method was also discussed. The results showed that soil respiration rate presented a single peak trend under four tillage methods during the summer corn growing season, and the maximum value was recorded at the heading stage. The trends of soil respiration were as follows: heading stage > flowering stage > grain filling stage > maturity stage > jointing stage > seedling stage. The trends of soil respiration under different tillage systems were as follows: CT > ST > RT > NT. There was a significant correlation between soil respiration rate and soil temperatures (P soil respiration using exponential function equation. However, there was no significant correlation between soil respiration rate and soil moisture. Root respiration accounted for 45.13%-56.86% of the proportion of soil respiratio n with the mean value 51.72% during the summer corn growing season under different tillage systems. Therefore, root exclusion method could be used to study the contribution of crop growth to carbon emission, to compare effects of different tillage systems on the contribution of root respiration provides the bases for selecting the measures to slow down the decomposition of soil carbon.

  8. On the temporal variation of leaf magnetic parameters: seasonal accumulation of leaf-deposited and leaf-encapsulated particles of a roadside tree crown.

    Science.gov (United States)

    Hofman, Jelle; Wuyts, Karen; Van Wittenberghe, Shari; Samson, Roeland

    2014-09-15

    Understanding the accumulation behaviour of atmospheric particles inside tree leaves is of great importance for the interpretation of biomagnetic monitoring results. In this study, we evaluated the temporal variation of the saturation isothermal remanent magnetisation (SIRM) of leaves of a roadside urban Platanus × acerifolia Willd. tree in Antwerp, Belgium. We hereby examined the seasonal development of the total leaf SIRM signal as well as the leaf-encapsulated fraction of the deposited dust, by washing the leaves before biomagnetic analysis. On average 38% of the leaf SIRM signal was exhibited by the leaf-encapsulated particles. Significant correlations were found between the SIRM and the cumulative daily average atmospheric PM10 and PM2.5 measurements. Moreover, a steady increase of the SIRM throughout the in-leaf season was observed endorsing the applicability of biomagnetic monitoring as a proxy for the time-integrated PM exposure of urban tree leaves. Strongest correlations were obtained for the SIRM of the leaf-encapsulated particles which confirms the dynamic nature of the leaf surface-accumulated particles. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. A Simple Paper-Based Microfluidic Device for the Determination of the Total Amino Acid Content in a Tea Leaf Extract

    Science.gov (United States)

    Cai, Longfei; Wu, Yunying; Xu, Chunxiu; Chen, Zefeng

    2013-01-01

    An experiment was developed to demonstrate a microfluidic device in the analytical chemistry (instrumental analysis) laboratory. Students made the paper-based microfluidic device with a wax pen and a piece of filter paper and used it to determine the total quantity of amino acids in a green tea leaf

  10. Phytochemicals Screening, Total Phenol Estimation, Antioxidant Activity of Blainvillea Acmella Leaf and Stem Successive Extracts

    International Nuclear Information System (INIS)

    Sharma, P.; Sharma, G.N.; Shrivastava, B.; Jadhav, H.R.

    2014-01-01

    The aim of present work was to investigate antioxidant potential of different extracts of Blainvillea acmella leaf and stem. The successive extraction of individual plant part was carried out using solvents of different polarity viz. n-hexane, ethyl acetate, methanol and water. Preliminary phyto chemical screening of all the extracts was done. The present total phenolic contents were estimated by Folin-Ciocalteu reagent method and expressed as μg/ mg of gallic acid equivalent. The antioxidant potential and reducing power of all the prepared extracts were measured against DPPH, as compared to standard ascorbic acid, and BHA respectively. The result data indicate that the phenolic contents were higher in methanolic extracts of leaf (73.67 ± 0.38 mg/ g) followed by ethyl acetate (29.08 ± 0.38 mg/ g), aqueous (21.50 ± 0.28 mg/ g), and n-Hexane (9.29 ± 0.38 mg/ g); gallic acid equivalent. The similar pattern in stem part was also observed for example methanolic extracts (41.90 ± 0.45 mg/ g), ethyl acetate (21.92 ± 0.28 mg/ g), aqueous (15.13 ± 0.18 mg/ g), and n-Hexane (3.69 ± 0.28 mg/ g). The antioxidant capacity of methanolic extract of both the part for example leaf and stem was found to be maximum, as IC50 values were 226.49 ± 0.16, 402.05 ± 1.10 respectively. The reducing power was also highest in methanol extract of both parts. The result data conclude that the higher antioxidant as well as reducing power may be due to present phenolic contents. (author)

  11. Partitioning autotrophic and heterotrophic respiration at Howland Forest

    Science.gov (United States)

    Carbone, Mariah; Hollinger, Dave; Davidson, Eric; Savage, Kathleen; Hughes, Holly

    2015-04-01

    Terrestrial ecosystem respiration is the combined flux of CO2 to the atmosphere from above- and below-ground, plant (autotrophic) and microbial (heterotrophic) sources. Flux measurements alone (e.g., from eddy covariance towers or soil chambers) cannot distinguish the contributions from these sources, which may change seasonally and respond differently to temperature and moisture. The development of improved process-based models that can predict how plants and microbes respond to changing environmental conditions (on seasonal, interannual, or decadal timescales) requires data from field observations and experiments to distinguish among these respiration sources. We tested the viability of partitioning of soil and ecosystem respiration into autotrophic and heterotrophic components with different approaches at the Howland Forest in central Maine, USA. These include an experimental manipulation using the classic root trenching approach and targeted ∆14CO2 measurements. For the isotopic measurements, we used a two-end member mass balance approach to determine the fraction of soil respiration from autotrophic and heterotrophic sources. When summed over the course of the growing season, the trenched chamber flux (heterotrophic) accounted for 53 ± 2% of the total control chamber flux. Over the four different 14C sampling periods, the heterotrophic component ranged from 35-55% and the autotrophic component ranges 45-65% of the total flux. Next steps will include assessing the value of the flux partitioning for constraining a simple ecosystem model using a model-data fusion approach to reduce uncertainties in estimates of NPP and simulation of future soil C stocks and fluxes.

  12. Effects of elevated CO2 leaf diet on gypsy moth (Lepidoptera: Lymantriidae) respiration rates

    Science.gov (United States)

    Anita R. Foss; William J. Mattson; Terry M. Trier

    2013-01-01

    Elevated levels of CO2 affect plant growth and leaf chemistry, which in turn can alter host plant suitability for insect herbivores. We examined the suitability of foliage from trees grown from seedlings since 1997 at Aspen FACE as diet for the gypsy moth (Lymantria dispar L.) Lepidoptera: Lymantriidae: paper birch (...

  13. Thermal Acclimation of Photosynthesis and Respiration Differ Across Mature Conifer Species in a Boreal Forest Peatland

    Science.gov (United States)

    Dusenge, M. E.; Stinziano, J. R.; Warren, J.; Ward, E. J.; Wullschleger, S.; Hanson, P. J.; Way, D.

    2017-12-01

    Boreal forests are often assumed to be temperature-limited, and warming is therefore expected to stimulate their carbon uptake. However, much of our information on the ability of boreal conifers to acclimate photosynthesis and respiration to rising temperatures comes from seedlings. We measured net CO2 assimilation rates (A) and dark respiration (R) at 25 °C (A25 and R25) and at prevailing growth temperatures (Ag and Rg) in mature Picea mariana (spruce) and Larix laricina (tamarack) exposed to ambient, +2.25, +4.5, +6.75 and +9 °C warming treatments in open top chambers in the field at the SPRUCE experiment (MN, USA). In spruce, A25 and Ag were similar across plots in May and June. In August, spruce in warmer treatments had higher A25, an effect that was offset by warmer leaf temperatures in the Ag data. In tamarack, A25 was stimulated by warming in both June and August, an effect that was mainly offset by higher leaf temperatures when Ag was assessed in June, while in August, Ag was still slightly higher in the warmest treatments (+6.75 and +9) compared to the ambient plots. In spruce, R25 was enhanced in warm-grown trees in May, but was similar across treatments in June and August, indicating little acclimation of R. Rg slightly increased with warming treatments across the season in spruce. In contrast, R in tamarack thermally acclimated, as R25 decreased with warming. But while this acclimation generated homeostatic Rg in June, Rg in August was still highest in the warmest treatments. Our work suggests that the capacity for thermal acclimation in both photosynthesis and respiration varies among boreal tree species, which may lead to shifts in the performance of these species as the climate warms.

  14. Distinct responses of soil respiration to experimental litter manipulation in temperate woodland and tropical forest.

    Science.gov (United States)

    Bréchet, Laëtitia M; Lopez-Sangil, Luis; George, Charles; Birkett, Ali J; Baxendale, Catherine; Castro Trujillo, Biancolini; Sayer, Emma J

    2018-04-01

    Global change is affecting primary productivity in forests worldwide, and this, in turn, will alter long-term carbon (C) sequestration in wooded ecosystems. On one hand, increased primary productivity, for example, in response to elevated atmospheric carbon dioxide (CO 2 ), can result in greater inputs of organic matter to the soil, which could increase C sequestration belowground. On other hand, many of the interactions between plants and microorganisms that determine soil C dynamics are poorly characterized, and additional inputs of plant material, such as leaf litter, can result in the mineralization of soil organic matter, and the release of soil C as CO 2 during so-called "priming effects". Until now, very few studies made direct comparison of changes in soil C dynamics in response to altered plant inputs in different wooded ecosystems. We addressed this with a cross-continental study with litter removal and addition treatments in a temperate woodland (Wytham Woods) and lowland tropical forest (Gigante forest) to compare the consequences of increased litterfall on soil respiration in two distinct wooded ecosystems. Mean soil respiration was almost twice as high at Gigante (5.0 μmol CO 2  m -2  s -1 ) than at Wytham (2.7 μmol CO 2  m -2  s -1 ) but surprisingly, litter manipulation treatments had a greater and more immediate effect on soil respiration at Wytham. We measured a 30% increase in soil respiration in response to litter addition treatments at Wytham, compared to a 10% increase at Gigante. Importantly, despite higher soil respiration rates at Gigante, priming effects were stronger and more consistent at Wytham. Our results suggest that in situ priming effects in wooded ecosystems track seasonality in litterfall and soil respiration but the amount of soil C released by priming is not proportional to rates of soil respiration. Instead, priming effects may be promoted by larger inputs of organic matter combined with slower turnover rates.

  15. Respirators. Does your face fit

    Energy Technology Data Exchange (ETDEWEB)

    Caro, N M; Else, D

    1981-04-01

    The authors carried out a survey of face sizes of men and women of four different ethnic origins and carried out face-seal leakage trials on four corresponding test panels. No single respirator design is likely to fit all members of the workforce, and it may be necessary to stock respirators from more than one manufacturers.Three or four different respirators or size of respirator may be needed. However, the use of lossely-fitting respirators such as Airsteam helmets could remove the necessity for exhaustive fitting procedures.

  16. Lifetime return on investment increases with leaf lifespan among 10 Australian woodland species.

    Science.gov (United States)

    Falster, Daniel S; Reich, Peter B; Ellsworth, David S; Wright, Ian J; Westoby, Mark; Oleksyn, Jacek; Lee, Tali D

    2012-01-01

    • Co-occurring species often differ in their leaf lifespan (LL) and it remains unclear how such variation is maintained in a competitive context. Here we test the hypothesis that leaves of long-LL species yield a greater return in carbon (C) fixed per unit C or nutrient invested by the plant than those of short-LL species. • For 10 sympatric woodland species, we assessed three-dimensional shoot architecture, canopy openness, leaf photosynthetic light response, leaf dark respiration and leaf construction costs across leaf age sequences. We then used the YPLANT model to estimate light interception and C revenue along the measured leaf age sequences. This was done under a series of simulations that incorporated the potential covariates of LL in an additive fashion. • Lifetime return in C fixed per unit C, N or P invested increased with LL in all simulations. • In contrast to other recent studies, our results show that extended LL confers a fundamental economic advantage by increasing a plant's return on investment in leaves. This suggests that time-discounting effects, that is, the compounding of income that arises from quick reinvestment of C revenue, are key in allowing short-LL species to succeed in the face of this economic handicap. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

  17. Respirator field performance factors

    International Nuclear Information System (INIS)

    Skaggs, B.J.; DeField, J.D.; Strandberg, S.W.; Sutcliffe, C.R.

    1985-01-01

    The Industrial Hygiene Group assisted OSHA and the NRC in measurements of respirator performance under field conditions. They reviewed problems associated with sampling aerosols within the respirator in order to determine fit factors (FFs) or field performance factor (FPF). In addition, they designed an environmental chamber study to determine the effects of temperature and humidity on a respirator wearer

  18. Soil Respiration And Respiration Partitioning In An Oak-Savannah With A History Of Fertilization

    Science.gov (United States)

    Morris, K. A.; Nair, R.; Schrumpf, M.; Migliavacca, M.

    2017-12-01

    Soil respiration is a combination of autotrophic and heterotrophic components. These components have different controls and structurally complex ecosystems such as oak-savannahs offer an opportunity to study strongly contrasting conditions (ie., soil from under trees versus open areas) in an environment with similar soil mineralogy and climatic patterns. To measure respiration coming from plant roots, fungal hyphae, and free-living microbes we established stations of soil cores comprised of three selectively permeable meshes under tree canopies and in open grassy areas of a Holm Oak (Quercus ilex) savannah in Extremadura, Spain. Large plots of this ecosystem had previously been fertilized as part of a stoichiometeric imbalance study (in 2015). Stations were installed in Dec. 2016 within four plots; control, N added, P added, and N+P added. Respiration from cores was measured in campaigns at key phenological stages with a portable Li-Cor 8100A unit. Six months after installation > 50% of soil respiration was attributable to free-living microbes. There is a persistent effect of the prior fertilization, resulting in increased soil respiration in open areas regardless of fertilizer type, while respiration from under tree canopies had a varied response. Soil under tree canopies showed distinct sensitivity to stoichiometric imbalance, meaning that addition of N or P alone either did not change respiration or decreased it slightly, while N+P stimulated respiration. We determined that respiration from free-living microbes is a major component of soil respiration even in the most active plant growing season. However, because of the lag between the time of fertilization and the time of measurement, it not possible to say whether treatment responses are due solely to nutrient status of the soil or whether changes in plant biomass and species composition also play a role. Additional work planned at the site will shed light on this uncertainty as well as the contribution of

  19. Influence of temperature and organic matter content on soil respiration in a deciduous oak forest

    Directory of Open Access Journals (Sweden)

    Zsolt Kotroczó

    2014-12-01

    Full Text Available The increasing temperature enhances soil respiration differently depend on different conditions (soil moisture, soil organic matter, the activity of soil microbes. It is an essential factor to predicting the effect of climate change on soil respiration. In a temperate deciduous forest (North-Hungary we added or removal aboveground and belowground litter to determine total soil respiration. We investigated the relationship between total soil CO2 efflux, soil moisture and soil temperature. Soil CO2 efflux was measured at each plot using chamber based soil respiration measurements. We determined the temperature sensitivity of soil respiration. The effect of doubled litter was less than the effect of removal. We found that temperature was more influential in the control of soil respiration than soil moisture in litter removal treatments, particularly in the wetter root exclusion treatments (NR and NI (R2: 0.49-0.61. Soil moisture (R2: 0.18-0.24 and temperature (R2: 0.18-0.20 influenced soil respiration similarly in treatments, where soil was drier (Control, Double Litter, Double Wood. A significantly greater increase in temperature induced higher soil respiration were significantly higher (2-2.5-fold in root exclusion treatments, where soil was wetter throughout the year, than in control and litter addition treatments. The highest bacterial and fungal count was at the DL treatment but the differences is not significant compared to the Control. The bacterial number at the No Litter, No Root, No Input treatment was significantly lower at the Control. Similar phenomenon can be observed at the fungal too, but the differences are not significant. The results of soil respiration suggest that the soil aridity can reduce soil respiration increases with the temperature increase. Soil bacterial and fungal count results show the higher organic matter content and soil surface cover litter favors the activity.

  20. Leaf and canopy photosynthesis of a chlorophyll deficient soybean mutant.

    Science.gov (United States)

    Sakowska, Karolina; Alberti, Giorgio; Genesio, Lorenzo; Peressotti, Alessandro; Delle Vedove, Gemini; Gianelle, Damiano; Colombo, Roberto; Rodeghiero, Mirco; Panigada, Cinzia; Juszczak, Radosław; Celesti, Marco; Rossini, Micol; Haworth, Matthew; Campbell, Benjamin W; Mevy, Jean-Philippe; Vescovo, Loris; Cendrero-Mateo, M Pilar; Rascher, Uwe; Miglietta, Franco

    2018-03-02

    The photosynthetic, optical, and morphological characteristics of a chlorophyll-deficient (Chl-deficient) "yellow" soybean mutant (MinnGold) were examined in comparison with 2 green varieties (MN0095 and Eiko). Despite the large difference in Chl content, similar leaf photosynthesis rates were maintained in the Chl-deficient mutant by offsetting the reduced absorption of red photons by a small increase in photochemical efficiency and lower non-photochemical quenching. When grown in the field, at full canopy cover, the mutants reflected a significantly larger proportion of incoming shortwave radiation, but the total canopy light absorption was only slightly reduced, most likely due to a deeper penetration of light into the canopy space. As a consequence, canopy-scale gross primary production and ecosystem respiration were comparable between the Chl-deficient mutant and the green variety. However, total biomass production was lower in the mutant, which indicates that processes other than steady state photosynthesis caused a reduction in biomass accumulation over time. Analysis of non-photochemical quenching relaxation and gas exchange in Chl-deficient and green leaves after transitions from high to low light conditions suggested that dynamic photosynthesis might be responsible for the reduced biomass production in the Chl-deficient mutant under field conditions. © 2018 John Wiley & Sons Ltd.

  1. Cardiac, skeletal, and smooth muscle mitochondrial respiration: are all mitochondria created equal?

    Science.gov (United States)

    Park, Song-Young; Gifford, Jayson R; Andtbacka, Robert H I; Trinity, Joel D; Hyngstrom, John R; Garten, Ryan S; Diakos, Nikolaos A; Ives, Stephen J; Dela, Flemming; Larsen, Steen; Drakos, Stavros; Richardson, Russell S

    2014-08-01

    Unlike cardiac and skeletal muscle, little is known about vascular smooth muscle mitochondrial respiration. Therefore, the present study examined mitochondrial respiratory rates in smooth muscle of healthy human feed arteries and compared with that of healthy cardiac and skeletal muscles. Cardiac, skeletal, and smooth muscles were harvested from a total of 22 subjects (53 ± 6 yr), and mitochondrial respiration was assessed in permeabilized fibers. Complex I + II, state 3 respiration, an index of oxidative phosphorylation capacity, fell progressively from cardiac to skeletal to smooth muscles (54 ± 1, 39 ± 4, and 15 ± 1 pmol·s(-1)·mg(-1), P respiration rates were normalized by CS (respiration per mitochondrial content), oxidative phosphorylation capacity was no longer different between the three muscle types. Interestingly, complex I state 2 normalized for CS activity, an index of nonphosphorylating respiration per mitochondrial content, increased progressively from cardiac to skeletal to smooth muscles, such that the respiratory control ratio, state 3/state 2 respiration, fell progressively from cardiac to skeletal to smooth muscles (5.3 ± 0.7, 3.2 ± 0.4, and 1.6 ± 0.3 pmol·s(-1)·mg(-1), P respiration highlight the existence of intrinsic functional differences between these muscle mitochondria. This likely influences the efficiency of oxidative phosphorylation and could potentially alter ROS production.

  2. Measurement for the MLC leaf velocity profile by considering the leaf leakage using a radiographic film

    International Nuclear Information System (INIS)

    Chow, James C L; Grigorov, Grigor N

    2006-01-01

    A method to measure the velocity profile of a multi-leaf collimator (MLC) leaf along its travel range using a radiographic film is reported by considering the intra-leaf leakage. A specific dynamic MLC field with leaves travelling from the field edge to the isocentre line was designed. The field was used to expose a radiographic film, which was then scanned, and the dose profile along the horizontal leaf axis was measured. The velocity at a sampling point on the film can be calculated by considering the horizontal distance between the sampling point and the isocentre line, dose at the sampling point, dose rate of the linear accelerator, the total leaf travel time from the field edge to isocentre line and the pre-measured dose rate of leaf leakage. With the leaf velocities and velocity profiles for all MLC leaves measured routinely, a comprehensive and simple QA for the MLC can be set up to test the consistency of the leaf velocity performance which is essential to the IMRT delivery using a sliding window technique. (note)

  3. Prediction of rate of CO2 assimilation of leaf lettuce under low light irradiation during storage

    International Nuclear Information System (INIS)

    Uchino, T.; Harada, F.; Hu, W.

    2003-01-01

    The rate of CO 2 assimilation of leaf lettuce changed with its respiration rate and gas constitution in a storage chamber. The optimum irradiance on the surface of leaf lettuce during storage using low light irradiation can be obtained by the prediction of the rate of CO 2 assimilation. For the above mentioned purpose the following equation were derived. -kd[C]/dt=0.5(1-f)I([C]-Γ/4.5[C]+10.5Γ)-ae -bt where, k: proportional constant (4.87×10 -3 mol⋅m -2 ) [C]: CO 2 concentration (ppm), t: time (h), f: fraction of light not absorbed by chloroplasts (0.23), I: irradiance (μmol⋅m-2⋅s -1 ), Γ: CO 2 compensation point without respiration (21.5ppm), a, b: parameters (0.308μmol⋅m -2 ⋅s -1 , 0.010h -1 ). Calculated values of rate of CO 2 assimilation by the equation agreed well with experimental ones at 3.4 and 6.5μmol⋅m -2 ⋅s -1 of irradiance, so it appeared that the assimilation rate could be sufficiently predicted

  4. Temperature acclimation of photosynthesis and respiration: A key uncertainty in the carbon cycle-climate feedback

    Science.gov (United States)

    Lombardozzi, Danica L.; Bonan, Gordon B.; Smith, Nicholas G.; Dukes, Jeffrey S.; Fisher, Rosie A.

    2015-10-01

    Earth System Models typically use static responses to temperature to calculate photosynthesis and respiration, but experimental evidence suggests that many plants acclimate to prevailing temperatures. We incorporated representations of photosynthetic and leaf respiratory temperature acclimation into the Community Land Model, the terrestrial component of the Community Earth System Model. These processes increased terrestrial carbon pools by 20 Pg C (22%) at the end of the 21st century under a business-as-usual (Representative Concentration Pathway 8.5) climate scenario. Including the less certain estimates of stem and root respiration acclimation increased terrestrial carbon pools by an additional 17 Pg C (~40% overall increase). High latitudes gained the most carbon with acclimation, and tropical carbon pools increased least. However, results from both of these regions remain uncertain; few relevant data exist for tropical and boreal plants or for extreme temperatures. Constraining these uncertainties will produce more realistic estimates of land carbon feedbacks throughout the 21st century.

  5. LEAF RESIDUE DECOMPOSITION OF SELECTED ATLANTIC FOREST TREE SPECIES

    Directory of Open Access Journals (Sweden)

    Helga Dias Arato

    2018-02-01

    Full Text Available ABSTRACT Biogeochemical cycling is essential to establish and maintain plant and animal communities. Litter is one of main compartments of this cycle, and the kinetics of leaf decomposition in forest litter depend on the chemical composition and environmental conditions. This study evaluated the effect of leaf composition and environmental conditions on leaf decomposition of native Atlantic Forest trees. The following species were analyzed: Mabea fistulifera Mart., Bauhinia forficata Link., Aegiphila sellowiana Cham., Zeyheria tuberculosa (Vell, Luehea grandiflora Mart. et. Zucc., Croton floribundus Spreng., Trema micrantha (L Blume, Cassia ferruginea (Schrad Schrad ex DC, Senna macranthera (DC ex Collad. H. S. Irwin and Barney and Schinus terebinthifolius Raddi (Anacardiaceae. For each species, litter bags were distributed on and fixed to the soil surface of soil-filled pots (in a greenhouse, or directly to the surface of the same soil type in a natural forest (field. Every 30 days, the dry weight and soil basal respiration in both environments were determined. The cumulative decomposition of leaves varied according to the species, leaf nutrient content and environment. In general, the decomposition rate was lowest for Aegiphila sellowiana and fastest for Bauhinia forficate and Schinus terebinthifolius. This trend was similar under the controlled conditions of a greenhouse and in the field. The selection of species with a differentiated decomposition pattern, suited for different stages of the recovery process, can help improve soil restoration.

  6. Respirator use and its impact on particulate matter exposure in aluminum manufacturing facilities.

    Science.gov (United States)

    Liu, Sa; Noth, Elizabeth; Eisen, Ellen; Cullen, Mark R; Hammond, Katharine

    2018-05-31

    Objectives As part of a large epidemiologic study of particulate health effect, this study aimed to report respirator use among total particulate matter (TPM) samples collected in a major aluminum manufacturing company from 1966‒2013 and evaluate the impact of respirator-use adjustment on exposure estimation. Methods Descriptive analyses were performed to evaluate respirator use across facilities and by facility type and job. Protection factors were applied to TPM measurements for recorded respirator use. Estimated TPM exposure for each job ‒ before and after respirator-use adjustment ‒ were compared to assess the impact of adjustment on exposure estimation. Results Respirator use was noted for 37% of 12 402 full-shift personal TPM samples. Measured TPM concentration ranged from less than detectable to 8220 mg/m3, with arithmetic mean, median and standard deviation being 10.6, 0.87 and 130 mg/m 3 , respectively. Respirators were used more often in smelting facilities (52% of TPM measurements) than in fabricating (17%) or refinery facilities (28%) (Pfacilities were subject to respirator-use adjustment, whereas it was 20% and 70% in fabricating and refinery facilities, respectively. Applying protection factors to TPM measurements significantly reduced estimated job mean TPM exposures and changed exposure categories in these facilities, with larger impact in smelting than fabricating facilities. Conclusions Respirator use varied by time, facility and job. Adjusting respirator use resulted in differential impact in smelting and fabricating facilities, which will need to be incorporated into ongoing epidemiologic studies accordingly.

  7. A non-destructive method for estimating onion leaf area

    Directory of Open Access Journals (Sweden)

    Córcoles J.I.

    2015-06-01

    Full Text Available Leaf area is one of the most important parameters for characterizing crop growth and development, and its measurement is useful for examining the effects of agronomic management on crop production. It is related to interception of radiation, photosynthesis, biomass accumulation, transpiration and gas exchange in crop canopies. Several direct and indirect methods have been developed for determining leaf area. The aim of this study is to develop an indirect method, based on the use of a mathematical model, to compute leaf area in an onion crop using non-destructive measurements with the condition that the model must be practical and useful as a Decision Support System tool to improve crop management. A field experiment was conducted in a 4.75 ha commercial onion plot irrigated with a centre pivot system in Aguas Nuevas (Albacete, Spain, during the 2010 irrigation season. To determine onion crop leaf area in the laboratory, the crop was sampled on four occasions between 15 June and 15 September. At each sampling event, eight experimental plots of 1 m2 were used and the leaf area for individual leaves was computed using two indirect methods, one based on the use of an automated infrared imaging system, LI-COR-3100C, and the other using a digital scanner EPSON GT-8000, obtaining several images that were processed using Image J v 1.43 software. A total of 1146 leaves were used. Before measuring the leaf area, 25 parameters related to leaf length and width were determined for each leaf. The combined application of principal components analysis and cluster analysis for grouping leaf parameters was used to reduce the number of variables from 25 to 12. The parameter derived from the product of the total leaf length (L and the leaf diameter at a distance of 25% of the total leaf length (A25 gave the best results for estimating leaf area using a simple linear regression model. The model obtained was useful for computing leaf area using a non

  8. Photodegradation of Leaf Litter in Water-Limited Ecosystems

    Science.gov (United States)

    Cory, R. M.; Powers, H.; McDowell, N.; Rahn, T.

    2008-12-01

    The longstanding view of terrestrial decomposition holds that heterotrophic respiration drives release of CO2, but recent studies, such as Austin and Vivanco (2006) have shown that in water-limited environments, photochemical decomposition of leaf litter may be equally or more effective than microbial decomposition. Although initial studies have concluded that photochemical degradation can be important in some environments, it has been difficult to quantify and the oxidative mechanisms involved remain unknown. Thus, the objectives of our study were to (1) quantify the CO2 emitted during photochemical degradation of leaf litter and (2) use the stable isotopic signatures of evolved CO2 to elucidate pathways of production. Emitted CO2 and its isotopic signature were measured using a tunable diode laser (TDL) to assess the pool of photochemically-labile plant matter (δ13C-CO2) in a given sample and to assess the source of the oxygen (δ18O-CO2). We quantified the photochemical release of CO2 and its isotopic signature from dried leaf litter of 10 tree and grass species prevalent in major biotic zones of New Mexico. The cumulative CO2 released upon exposure of 0.1-0.3 g of dried leaf litter to three hours of simulated sunlight ranged from 8-25 mg CO2-C g-1 dried litter, corresponding to 1-2% mass loss. Generally, the δ13C-CO2 was more depleted (4-7 ± 2 per mil) than the average δ13C of the respective leaf litter sample. The δ18O-CO2 evolved is approximately equal to δ18O of atmospheric O2, suggesting that the oxidation mechanism involves direct reaction with atmospheric O2.

  9. Light drives vertical gradients of leaf morphology in a sugar maple (Acer saccharum) forest.

    Science.gov (United States)

    Coble, Adam P; Cavaleri, Molly A

    2014-02-01

    Leaf mass per area (LMA, g m(-2)) is an essential trait for modeling canopy function due to its strong association with photosynthesis, respiration and leaf nitrogen. Leaf mass per area, which is influenced by both leaf thickness and density (LMA = thickness × density), generally increases from the bottom to the top of tree canopies, yet the mechanisms behind this universal pattern are not yet resolved. For decades, the light environment was assumed to be the most influential driver of within-canopy variation in LMA, yet recent evidence has shown hydrostatic gradients to be more important in upper canopy positions, especially in tall evergreen trees in temperate and tropical forests. The aim of this study was to disentangle the importance of various environmental drivers on vertical LMA gradients in a mature sugar maple (Acer saccharum Marshall) forest. We compared LMA, leaf density and leaf thickness relationships with height, light and predawn leaf water potential (ΨPre) within a closed and an exposed canopy to assess leaf morphological traits at similar heights but different light conditions. Contrary to our expectations and recent findings in the literature, we found strong evidence that light was the primary driver of vertical gradients in leaf morphology. At similar heights (13-23 m), LMA was greater within the exposed canopy than the closed canopy, and light had a stronger influence over LMA compared with ΨPre. Light also had a stronger influence over both leaf thickness and density compared with ΨPre; however, the increase in LMA within both canopy types was primarily due to increasing leaf thickness with increasing light availability. This study provides strong evidence that canopy structure and crown exposure, in addition to height, should be considered as a parameter for determining vertical patterns in LMA and modeling canopy function.

  10. Vegetation types alter soil respiration and its temperature sensitivity at the field scale in an estuary wetland.

    Directory of Open Access Journals (Sweden)

    Guangxuan Han

    Full Text Available Vegetation type plays an important role in regulating the temporal and spatial variation of soil respiration. Therefore, vegetation patchiness may cause high uncertainties in the estimates of soil respiration for scaling field measurements to ecosystem level. Few studies provide insights regarding the influence of vegetation types on soil respiration and its temperature sensitivity in an estuary wetland. In order to enhance the understanding of this issue, we focused on the growing season and investigated how the soil respiration and its temperature sensitivity are affected by the different vegetation (Phragmites australis, Suaeda salsa and bare soil in the Yellow River Estuary. During the growing season, there were significant linear relationships between soil respiration rates and shoot and root biomass, respectively. On the diurnal timescale, daytime soil respiration was more dependent on net photosynthesis. A positive correlation between soil respiration and net photosynthesis at the Phragmites australis site was found. There were exponential correlations between soil respiration and soil temperature, and the fitted Q10 values varied among different vegetation types (1.81, 2.15 and 3.43 for Phragmites australis, Suaeda salsa and bare soil sites, respectively. During the growing season, the mean soil respiration was consistently higher at the Phragmites australis site (1.11 µmol CO2 m(-2 s(-1, followed by the Suaeda salsa site (0.77 µmol CO2 m(-2 s(-1 and the bare soil site (0.41 µmol CO2 m(-2 s(-1. The mean monthly soil respiration was positively correlated with shoot and root biomass, total C, and total N among the three vegetation patches. Our results suggest that vegetation patchiness at a field scale might have a large impact on ecosystem-scale soil respiration. Therefore, it is necessary to consider the differences in vegetation types when using models to evaluate soil respiration in an estuary wetland.

  11. Vegetation Types Alter Soil Respiration and Its Temperature Sensitivity at the Field Scale in an Estuary Wetland

    Science.gov (United States)

    Han, Guangxuan; Xing, Qinghui; Luo, Yiqi; Rafique, Rashad; Yu, Junbao; Mikle, Nate

    2014-01-01

    Vegetation type plays an important role in regulating the temporal and spatial variation of soil respiration. Therefore, vegetation patchiness may cause high uncertainties in the estimates of soil respiration for scaling field measurements to ecosystem level. Few studies provide insights regarding the influence of vegetation types on soil respiration and its temperature sensitivity in an estuary wetland. In order to enhance the understanding of this issue, we focused on the growing season and investigated how the soil respiration and its temperature sensitivity are affected by the different vegetation (Phragmites australis, Suaeda salsa and bare soil) in the Yellow River Estuary. During the growing season, there were significant linear relationships between soil respiration rates and shoot and root biomass, respectively. On the diurnal timescale, daytime soil respiration was more dependent on net photosynthesis. A positive correlation between soil respiration and net photosynthesis at the Phragmites australis site was found. There were exponential correlations between soil respiration and soil temperature, and the fitted Q 10 values varied among different vegetation types (1.81, 2.15 and 3.43 for Phragmites australis, Suaeda salsa and bare soil sites, respectively). During the growing season, the mean soil respiration was consistently higher at the Phragmites australis site (1.11 µmol CO2 m−2 s−1), followed by the Suaeda salsa site (0.77 µmol CO2 m−2 s−1) and the bare soil site (0.41 µmol CO2 m−2 s−1). The mean monthly soil respiration was positively correlated with shoot and root biomass, total C, and total N among the three vegetation patches. Our results suggest that vegetation patchiness at a field scale might have a large impact on ecosystem-scale soil respiration. Therefore, it is necessary to consider the differences in vegetation types when using models to evaluate soil respiration in an estuary wetland. PMID:24608636

  12. Facepiece leakage and fitting of respirators

    International Nuclear Information System (INIS)

    White, J.M.

    1978-05-01

    The ways in which airborne contaminants can penetrate respirators and the factors which affect the fit of respirators are discussed. The fit of the respirator to the face is shown to be the most critical factor affecting the protection achieved by the user. Qualitative and quantitative fit testing techniques are described and their application to industrial respirator programs is examined. Quantitative measurement of the leakage of a respirator while worn can be used to numerically indicate the protection achieved. These numbers, often referred to as protection factors, are sometimes used as the basis for selecting suitable respirators and this practice is reviewed. (author)

  13. Arbuscular Mycorrhizal Symbiosis with Arundo donax Decreases Root Respiration and Increases Both Photosynthesis and Plant Biomass Accumulation.

    Science.gov (United States)

    Romero-Munar, Antònia; Del-Saz, Néstor Fernández; Ribas-Carbó, Miquel; Flexas, Jaume; Baraza, Elena; Florez-Sarasa, Igor; Fernie, Alisdair Robert; Gulías, Javier

    2017-07-01

    The effect of arbuscular mycorrhiza (AM) symbiosis on plant growth is associated with the balance between costs and benefits. A feedback regulation loop has been described in which the higher carbohydrate cost to plants for AM symbiosis is compensated by increases in their photosynthetic rates. Nevertheless, plant carbon balance depends both on photosynthetic carbon uptake and respiratory carbon consumption. The hypothesis behind this research was that the role of respiration in plant growth under AM symbiosis may be as important as that of photosynthesis. This hypothesis was tested in Arundo donax L. plantlets inoculated with Rhizophagus irregularis and Funneliformis mosseae. We tested the effects of AM inoculation on both photosynthetic capacity and in vivo leaf and root respiration. Additionally, analyses of the primary metabolism and ion content were performed in both leaves and roots. AM inoculation increased photosynthesis through increased CO 2 diffusion and electron transport in the chloroplast. Moreover, respiration decreased only in AM roots via the cytochrome oxidase pathway (COP) as measured by the oxygen isotope technique. This decline in the COP can be related to the reduced respiratory metabolism and substrates (sugars and tricarboxylic acid cycle intermediates) observed in roots. © 2017 John Wiley & Sons Ltd.

  14. Final report on the safety assessment of AloeAndongensis Extract, Aloe Andongensis Leaf Juice,aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice,aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract.

    Science.gov (United States)

    2007-01-01

    Review Expert Panel concluded that anthraquinone levels in the several Aloe Barbadensis extracts are well understood and can conform to the industry-established level of 50 ppm. Although the phototoxicity anthraquinone components of Aloe plants have been demonstrated, several clinical studies of preparations derived from Aloe barbadensis plants demonstrated no phototoxicity, confirming that the concentrations of anthraquinones in such preparations are too low to induce phototoxicity. The characterization of aloe-derived ingredients from other species is not clear. In the absence of well-characterized derivatives, biological studies of these materials are considered necessary. The studies needed are 28-day dermal toxicity studies on Aloe Andongensis Extract, Aloe Andongensis Leaf Juice, Aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice (ingredients should be tested at current use concentrations). In Aloe-derived ingredients used in cosmetics, regardless of species, anthraquinone levels should not exceed 50 ppm. The Cosmetic Ingredient Review Expert Panel advised the industry that the total polychlorobiphenyl (PCB)/pesticide contamination of any plant-derived cosmetic ingredient should be limited to not more than 40 ppm, with not more than 10 ppm for any specific residue and that limits were appropriate for the following impurities: arsenic (3 mg/kg maximum), heavy metals (20 mg/kg maximum), and lead (5 mg/kg maximum).

  15. Height-related changes in leaf photosynthetic traits in diverse Bornean tropical rain forest trees.

    Science.gov (United States)

    Kenzo, Tanaka; Inoue, Yuta; Yoshimura, Mitsunori; Yamashita, Megumi; Tanaka-Oda, Ayumi; Ichie, Tomoaki

    2015-01-01

    Knowledge of variations in morphophysiological leaf traits with forest height is essential for quantifying carbon and water fluxes from forest ecosystems. Here, we examined changes in leaf traits with forest height in diverse tree species and their role in environmental acclimation in a tropical rain forest in Borneo that does not experience dry spells. Height-related changes in leaf physiological and morphological traits [e.g., maximum photosynthetic rate (Amax), stomatal conductance (gs), dark respiration rate (Rd), carbon isotope ratio (δ(13)C), nitrogen (N) content, and leaf mass per area (LMA)] from understory to emergent trees were investigated in 104 species in 29 families. We found that many leaf area-based physiological traits (e.g., A(max-area), Rd, gs), N, δ(13)C, and LMA increased linearly with tree height, while leaf mass-based physiological traits (e.g., A(max-mass)) only increased slightly. These patterns differed from other biomes such as temperate and tropical dry forests, where trees usually show decreased photosynthetic capacity (e.g., A(max-area), A(max-mass)) with height. Increases in photosynthetic capacity, LMA, and δ(13)C are favored under bright and dry upper canopy conditions with higher photosynthetic productivity and drought tolerance, whereas lower R d and LMA may improve shade tolerance in lower canopy trees. Rapid recovery of leaf midday water potential to theoretical gravity potential during the night supports the idea that the majority of trees do not suffer from strong drought stress. Overall, leaf area-based photosynthetic traits were associated with tree height and the degree of leaf drought stress, even in diverse tropical rain forest trees.

  16. Soil respiration shifts as drought-induced tree substitution advances from Scots pine to Holm oak forest

    Science.gov (United States)

    Barba, Josep; Curiel Yuste, Jorge; Poyatos, Rafael; Janssens, Ivan A.; Lloret, Francisco

    2014-05-01

    There is more and more evidences that the current global warming trend and the increase of frequency and intensity of drought events during the last decades in the Northern hemisphere are currently producing an increment of drought-induced forest die-off events, being the Mediterranean region one of the most affected areas. This drought-induced mortality could lead in a vegetation shift with unpredicted consequences in carbon pools, where soils are the most determinant factor in this carbon balance as they contain over two-thirds of carbon on forest ecosystems. There are several uncertainties related on the interaction between soil, environmental conditions and vegetation shifts that could modify their capability to be net carbon sinks or sources in a warming context. We studied soil respiration and its heterotrophic (RH) and autotrophic (Ra) (split in fine roots [Rr] and mycorrhizal respiration [Rs]) components in a mixed Mediterranean forest where Scots pine (Pinus sylvestris L.) are suffering from drought-induced die-off and replaced by Holm oak (Quercus ilex L.) as the dominant tree species. Soil respiration fluxes and its fractions were measured every two weeks during one year at four stages of the substitution process (non defoliated pines [NDP], defoliated pines [DFP], dead pines [DP] and Holm oak [HO]), using the mesh exclusion method. The aims were (i) to describe soil respiration fluxes in a drought-induced secondary successional process, (ii) to test whether the changes in vegetation affected soil respiration fluxes and (iii) to determine the influence of environmental and abiotic variables on the different soil respiration fractions. Total soil respiration was 10.10±6.17 TC ha-1 y-1, RH represented the 67% of the total, Ra represented the 34% of the total, and Rr and Rs were the 22 and 12%, respectively. Significant differences were found in total soil respiration and RH between NDP and HO, being lower in HO than in NDP (34% in total and 48% in RH). No

  17. Heterotrophic components of soil respiration in pastures and forests in southwestern Amazonia, Acre, Brazil

    Directory of Open Access Journals (Sweden)

    Eric Atlas Davidson

    2008-12-01

    Full Text Available In this paper we present data on soil microbial biomass and heterotrophic respiration in pastures, mature and secondary forests, in order to elucidate their contribution to total CO2 flux from soil to atmosphere. The research was conducted in Southwestern Amazonia, Acre State, Brazil. Microbial biomass was estimated using a variation of the traditional fumigation-extraction method and heterotrophic respiration was measured using respirometry flasks attached to an infrared gas analyzer. Soil microbial biomass and heterotrophic respiration did not differ statistically among pastures, mature and secondary forests. These laboratory results indicate that higher CO2 fluxes from pasture soils measured in situ are probably due to higher root respiration by pasture grasses.

  18. Synchronized moving aperture radiation therapy (SMART): superimposing tumor motion on IMRT MLC leaf sequences under realistic delivery conditions

    International Nuclear Information System (INIS)

    Xu Jun; Papanikolaou, Nikos; Shi Chengyu; Jiang, Steve B

    2009-01-01

    Synchronized moving aperture radiation therapy (SMART) has been proposed to account for tumor motions during radiotherapy in prior work. The basic idea of SMART is to synchronize the moving radiation beam aperture formed by a dynamic multileaf collimator (DMLC) with the tumor motion induced by respiration. In this paper, a two-dimensional (2D) superimposing leaf sequencing method is presented for SMART. A leaf sequence optimization strategy was generated to assure the SMART delivery under realistic delivery conditions. The study of delivery performance using the Varian LINAC and the Millennium DMLC showed that clinical factors such as collimator angle, dose rate, initial phase and machine tolerance affect the delivery accuracy and efficiency. An in-house leaf sequencing software was developed to implement the 2D superimposing leaf sequencing method and optimize the motion-corrected leaf sequence under realistic clinical conditions. The analysis of dynamic log (Dynalog) files showed that optimization of the leaf sequence for various clinical factors can avoid beam hold-offs which break the synchronization of SMART and fail the SMART dose delivery. Through comparison between the simulated delivered fluence map and the planed fluence map, it was shown that the motion-corrected leaf sequence can greatly reduce the dose error.

  19. Interpreting, measuring, and modeling soil respiration

    Science.gov (United States)

    Michael G. Ryan; Beverly E. Law

    2005-01-01

    This paper reviews the role of soil respiration in determining ecosystem carbon balance, and the conceptual basis for measuring and modeling soil respiration. We developed it to provide background and context for this special issue on soil respiration and to synthesize the presentations and discussions at the workshop. Soil respiration is the largest component of...

  20. Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field.

    Science.gov (United States)

    Liang, Guopeng; Houssou, Albert A; Wu, Huijun; Cai, Dianxiong; Wu, Xueping; Gao, Lili; Li, Jing; Wang, Bisheng; Li, Shengping

    2015-01-01

    Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013-2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha(-1) year(-1) (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q10 ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013-2014 and 2014-2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013-2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014-2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration.

  1. [Temperature sensitivity of wheat plant respiration and soil respiration influenced by increased UV-B radiation from elongation to flowering periods].

    Science.gov (United States)

    Chen, Shu-Tao; Hu, Zheng-Hua; Li, Han-Mao; Ji, Yu-Hong; Yang, Yan-Ping

    2009-05-15

    Field experiment was carried out in the spring of 2008 in order to investigate the effects of increased UV-B radiation on the temperature sensitivity of wheat plant respiration and soil respiration from elongation to flowering periods. Static chamber-gas chromatography method was used to measure ecosystem respiration and soil respiration under 20% UV-B radiation increase and control. Environmental factors such as temperature and moisture were also measured. Results indicated that supplemental UV-B radiation inhibited the ecosystem respiration and soil respiration from wheat elongation to flowering periods, and the inhibition effect was more obvious for soil respiration than for ecosystem respiration. Ecosystem respiration rates, on daily average, were 9%, 9%, 3%, 16% and 30% higher for control than for UV-B treatment forthe five measurement days, while soil respiration rates were 99%, 93%, 106%, 38% and 10% higher for control than for UV-B treatment. The Q10s (temperature sensitivity coefficients) for plant respiration under control and UV-B treatments were 1.79 and 1.59, respectively, while the Q10s for soil respiration were 1.38 and 1.76, respectively. The Q10s for ecosystem respiration were 1.65 and 1.63 under CK and UV-B treatments, respectively. Supplemental UV-B radiation caused a lower Q10 for plant respiration and a higher Q10 for soil respiration, although no significant effect of supplemental UV-B radiation on the Q10 for ecosystem respiration was found.

  2. Personal exposure versus monitoring station data for respirable particles

    Energy Technology Data Exchange (ETDEWEB)

    Sega, K; Fugas, M

    1982-01-01

    Personal exposure to respirable particles of 12 subjects working at the same location, but living in various parts of Zagreb, was monitored for 7 consecutive days and compared with simultaneously obtained data from the outdoor network station nearest to subject's home. Although personal exposure is related to the outdoor pollution, other sources play a considerable role. Indoor exposure takes, on the average, more than 80% of the total time. The ratio between average personal exposure and respirable particle levels in the outdoor air decreases with the increased outdoor concentration (r = -0.93), indicating that this relationship might serve as a basis for a rough estimate of possible personal exposure.

  3. Effects of leaf movement on leaf temperature, transpiration and radiation interception in soybean under water stress conditions

    International Nuclear Information System (INIS)

    Isoda, A.; Wang, P.

    2001-01-01

    Varietal differences in leaf movement were examined in terms of radiation interception, leaf temperature and transpiration under water stressed conditions. Five cultivars (Qindou 7232, Gaofei 16, Dongnong 87 - 138, 8285 - 8 and 8874) were grown in a concrete frame field in Xinjiang, China. Irrigation treatments (irrigation and no irrigation) were made from the flowering to the pod filling stage. A leaflet in the uppermost layer of the canopy was restrained horizontally. Leaf temperatures, transpiration rate (stem sap flow rate of the main stem per unit leaf area) and intercepted radiation of each leaflet were measured. There were greater varietal differences in leaf movement, leaf temperature and transpiration rate. Leaf temperature seemed to be adjusted by leaf movement and transpiration. The extent to which is adjusted by leaf movement and transpiration differed among the cultivars; leaf temperature was influenced mainly by leaf movement for Gaofei 16 and Dongnong 87 - 138, mainly by transpiration for Qindou 7232 and 8874, and by both for 8285 - 8. Intercepted radiation in the upper two layers of the canopy (20 cm from the uppermost) was greater in the irrigated plot, although the mean values of total leaflets of the irrigated plot were not different as compared to the non-irrigated plot. Although paraheliotropic leaf movement decreased radiation interception, it offers some possibilities for the improvement in radiation penetration within a dense canopy. Cumulated amount of transpiration during a day was compared between the restrained-leaf and the non-leaf-restrained plants in 8874. Paraheliotropic leaf movement reduced water loss by 23% in the irrigated and 71% in the non-irrigated plots

  4. Controls on Ecosystem and Root Respiration in an Alaskan Peatland

    Science.gov (United States)

    McConnell, N. A.; McGuire, A. D.; Harden, J. W.; Kane, E. S.; Turetsky, M. R.

    2010-12-01

    Boreal ecosystems cover 14% of the vegetated surface on earth and account for 25-30% of the world’s soil carbon (C), mainly due to large carbon stocks in deep peat and frozen soil layers. While peatlands have served as historical sinks of carbon, global climate change may trigger re-release of C to the atmosphere and may turn these ecosystems into net C sources. Rates of C release from a peatland are determined by regional climate and local biotic and abiotic factors such as vegetation cover, thaw depth, and peat thickness. Soil CO2 fluxes are driven by both autotrophic (plant) respiration and heterotrophic (microbial) respiration. Thus, changes in plant and microbial activity in the soil will impact CO2 emissions from peatlands. In this study, we explored environmental and vegetation controls on ecosystem respiration and root respiration in a variety of wetland sites. The study was conducted at the Alaskan Peatland Experiment (APEX; www.uoguelph.ca/APEX) sites in the Bonanza Creek Experimental Forest located 35 km southwest of Fairbanks Alaska. We measured ecosystem respiration, root respiration, and monitored a suite of environmental variables along a vegetation and soil moisture gradient including a black spruce stand with permafrost, a shrubby site with permafrost, a tussock grass site, and a herbaceous open rich fen. Within the rich fen, we have been conducting water table manipulations including a control, lowered, and raised water table treatment. In each of our sites, we measured total ecosystem respiration using static chambers and root respiration by harvesting roots from the uppermost 20 cm and placing them in a root cuvette to obtain a root flux. Ecosystem respiration (ER) on a μmol/m2/sec basis varied across sites. Water table was a significant predictor of ER at the lowered manipulation site and temperature was a strong predictor at the control site in the rich fen. Water table and temperature were both significant predictors of ER at the raised

  5. Physiological mechanisms of drought-induced tree die-off in relation to carbon, hydraulic and respiratory stress in a drought-tolerant woody plant.

    Science.gov (United States)

    Saiki, Shin-Taro; Ishida, Atsushi; Yoshimura, Kenichi; Yazaki, Kenichi

    2017-06-07

    Drought-induced tree die-off related to climate change is occurring worldwide and affects the carbon stocks and biodiversity in forest ecosystems. Hydraulic failure and carbon starvation are two commonly proposed mechanisms for drought-induced tree die-off. Here, we show that inhibited branchlet respiration and soil-to-leaf hydraulic conductance, likely caused by cell damage, occur prior to hydraulic failure (xylem embolism) and carbon starvation (exhaustion of stored carbon in sapwood) in a drought-tolerant woody species, Rhaphiolepis wrightiana Maxim. The ratio of the total leaf area to the twig sap area was used as a health indicator after drought damage. Six adult trees with different levels of tree health and one dead adult tree were selected. Two individuals having the worst and second worst health among the six live trees died three months after our study was conducted. Soil-to-leaf hydraulic conductance and leaf gas exchange rates decreased linearly as tree health declined, whereas xylem cavitation and total non-structural carbon remained unchanged in the branchlets except in the dead and most unhealthy trees. Respiration rates and the number of living cells in the sapwood decreased linearly as tree health declined. This study is the first report on the importance of dehydration tolerance and respiration maintenance in living cells.

  6. Seasonal Patterns of Soil Respiration and Related Soil Biochemical Properties under Nitrogen Addition in Winter Wheat Field

    Science.gov (United States)

    Liang, Guopeng; Houssou, Albert A.; Wu, Huijun; Cai, Dianxiong; Wu, Xueping; Gao, Lili; Li, Jing; Wang, Bisheng; Li, Shengping

    2015-01-01

    Understanding the changes of soil respiration under increasing N fertilizer in cropland ecosystems is crucial to accurately predicting global warming. This study explored seasonal variations of soil respiration and its controlling biochemical properties under a gradient of Nitrogen addition during two consecutive winter wheat growing seasons (2013–2015). N was applied at four different levels: 0, 120, 180 and 240 kg N ha-1 year-1 (denoted as N0, N12, N18 and N24, respectively). Soil respiration exhibited significant seasonal variation and was significantly affected by soil temperature with Q10 ranging from 2.04 to 2.46 and from 1.49 to 1.53 during 2013–2014 and 2014–2015 winter wheat growing season, respectively. Soil moisture had no significant effect on soil respiration during 2013–2014 winter wheat growing season but showed a significant and negative correlation with soil respiration during 2014–2015 winter wheat growing season. Soil respiration under N24 treatment was significantly higher than N0 treatment. Averaged over the two growing seasons, N12, N18 and N24 significantly increased soil respiration by 13.4, 16.4 and 25.4% compared with N0, respectively. N addition also significantly increased easily extractable glomalin-related soil protein (EEG), soil organic carbon (SOC), total N, ammonium N and nitrate N contents. In addition, soil respiration was significantly and positively correlated with β-glucosidase activity, EEG, SOC, total N, ammonium N and nitrate N contents. The results indicated that high N fertilization improved soil chemical properties, but significantly increased soil respiration. PMID:26629695

  7. BOREAS TE-9 NSA Leaf Chlorophyll Density

    Science.gov (United States)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Margolis, Hank; Sy, Mikailou

    2000-01-01

    The BOREAS TE-9 team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. These data were collected to help provide an explanation of potential seasonal and spatial changes of leaf pigment properties in boreal forest species at the NSA. At different dates (FFC-Winter, FFC-Thaw, IFC-1, IFC-2, and IMC-3), foliage samples were collected from the upper third of the canopy for five NSA sites (YJP, OJP, OBS, UBS, and OA) near Thompson, Manitoba. Subsamples of 100 needles for black spruce, 20 needles for jack pine, and single leaf for trembling aspen were cut into pieces and immersed in a 20-mL DMF aliquot in a Nalgene test tube. The extracted foliage materials were then oven-dried at 68 C for 48 hours and weighed. Extracted leaf dry weight was converted to a total leaf area basis to express the chlorophyll content in mg/sq cm of total leaf area. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  8. Management effects on European cropland respiration

    DEFF Research Database (Denmark)

    Eugster, Werner; Moffat, Antje M.; Ceschia, Eric

    2010-01-01

    Increases in respiration rates following management activities in croplands are considered a relevant anthropogenic source of CO2. In this paper, we quantify the impact of management events on cropland respiration fluxes of CO2 as they occur under current climate and management conditions. Our....... This allowed us to address the question of how management activities influence ecosystem respiration. This was done by comparing respiration fluxes during 7, 14, and 28 days after the management with those observed during the matching time period before management. Median increases in respiration ranged from...... than management alone are also important at a given site. Temperature is the climatic factor that showed best correlation with site-specific respiration fluxes. Therefore, the effect of temperature changes between the time periods before and after management were taken into account for a subset of 13...

  9. Rapid, high-resolution measurement of leaf area and leaf orientation using terrestrial LiDAR scanning data

    International Nuclear Information System (INIS)

    Bailey, Brian N; Mahaffee, Walter F

    2017-01-01

    The rapid evolution of high performance computing technology has allowed for the development of extremely detailed models of the urban and natural environment. Although models can now represent sub-meter-scale variability in environmental geometry, model users are often unable to specify the geometry of real domains at this scale given available measurements. An emerging technology in this field has been the use of terrestrial LiDAR scanning data to rapidly measure the three-dimensional geometry of trees, such as the distribution of leaf area. However, current LiDAR methods suffer from the limitation that they require detailed knowledge of leaf orientation in order to translate projected leaf area into actual leaf area. Common methods for measuring leaf orientation are often tedious or inaccurate, which places constraints on the LiDAR measurement technique. This work presents a new method to simultaneously measure leaf orientation and leaf area within an arbitrarily defined volume using terrestrial LiDAR data. The novelty of the method lies in the direct measurement of the fraction of projected leaf area G from the LiDAR data which is required to relate projected leaf area to total leaf area, and in the new way in which radiation transfer theory is used to calculate leaf area from the LiDAR data. The method was validated by comparing LiDAR-measured leaf area to (1) ‘synthetic’ or computer-generated LiDAR data where the exact area was known, and (2) direct measurements of leaf area in the field using destructive sampling. Overall, agreement between the LiDAR and reference measurements was very good, showing a normalized root-mean-squared-error of about 15% for the synthetic tests, and 13% in the field. (paper)

  10. Economic analysis of implementing respirator program or ventilation system in a manufacturing environment

    International Nuclear Information System (INIS)

    Saidi-Mehrabab, M.

    2000-01-01

    The techniques and methods of developing cost models for respirators are discussed. Models are developed and implemented in this study for nineteen types of respirators in two major classes (air-purifying and supplied-air) and one L EV system. One respirator model is selected for detailed discussion from among the twenty models. The technical cost method is used in constructing the cost models for each of the respirators and the L EV system. In this methodology, the costs of purchasing and using a typical respirator or L EV system are divided into two categories, variable costs and fixed costs. Variable costs consists of the cost of replaceable components and probabilistic mortality cost. Fixed cost is the annualized capital requirement plus interest cost. The criteria for estimating some of the cost elements are based on existing equations in the literature, engineering judgement and manufacturer-provided information. A technical cost model results from the integration of this information into a computerized framework. The cost models for discussion are presented in the order of increasing computational complexity. Through the economic analysis, the lowest cost type in each class of respirator is determined. The determination criteria are based on the minimum total annual cost and highest benefit cost ratio. The selected lowest cost respirators are compared with the L EV system from the economic standpoint to reveal the cost optimal alternative

  11. Environmental controls on the carbon isotope composition of ecosystem-respired CO{sub 2} in contrasting forest ecosystems in Canada and the USA

    Energy Technology Data Exchange (ETDEWEB)

    Alstad, K.P. [Lethbridge Univ., Lethbridge, AB (Canada). Dept. of Biological Sciences; Toledo Univ., Toledo, OH (United States). Dept. of Environmental Sciences; Flanagan, L.B. [Lethbridge Univ., Lethbridge, AB (Canada). Dept. of Biological Sciences; Lai, C.T. [Utah Univ., Salt Lake City, UT (United States); San Diego State Univ., San Diego, CA (United States); Ehleringer, J.R. [Utah Univ., Salt Lake City, UT (United States)

    2007-10-15

    Eleven forest ecosystems in Canada and the United States were compared in order to test for differences among forest {delta}{sup 13} carbon (C) responses to seasonal variations in environmental conditions from May to October 2004. Carbon isotope composition of ecosystem-respired carbon dioxide (CO{sub 2}) was considered as a proxy for short-term changes in photosynthetic discrimination. The study compared coniferous and deciduous forests, as well as forests in boreal and coastal environments. It was hypothesized that the carbon isotope composition of ecosystem-respired CO{sub 2} varied in a manner consistent with results obtained in leaf-level studies. Results of the study showed that higher R{sup 2} values were obtained for coastal ecosystems. The relationships between {delta}{sup 13}C{sub R} and environmental conditions were consistent with results obtained from leaf-level studies. Vapour pressure deficits and soil temperatures were significant determinants of variations in {delta}{sup 13}C{sub R} in the boreal forest ecosystem. Variations in {delta}{sup 13}C{sub R} in the coastal forest ecosystem correlated with changes in photosynthetic photon flux (PPF). It was concluded that {delta}{sup 13}C{sub R} measurements can be used to assess yearly variations in ecosystem physiological responses to changing environmental conditions. 59 refs., 7 tabs., 6 figs.

  12. Effects of respirator use on worker performance

    Energy Technology Data Exchange (ETDEWEB)

    Cardarelli, R. [Yankee Atomic Electric Co., Bolton, MA (United States)

    1995-03-01

    In 1993, EPRI funded Yankee Atomic Electric Company to examine the effects of respirator use on worker efficiency. Phase I of Yankee`s effort was to develop a study design to determine respirator effects. Given success in Phase I, a larger population will be tested to determine if a stasitically significant respirator effect on performance can be measured. This paper summarizes the 1993 EPRI/Yankee Respirator Effects of Pilot Study, and describes the study design for the 1994 EPRI/Yankee Respirator Study to be conducted at the Oyster Creek Nuclear Power Plant. Also described is a summary of respirator effect studies that have been conducted during the last ten (10) years.

  13. Rates of Litter Decomposition and Soil Respiration in Relation to Soil Temperature and Water in Different-Aged Pinus massoniana Forests in the Three Gorges Reservoir Area, China

    Science.gov (United States)

    Zeng, Lixiong; Huang, Zhilin; Lei, Jingpin; Zhou, Benzhi; Li, Maihe

    2014-01-01

    To better understand the soil carbon dynamics and cycling in terrestrial ecosystems in response to environmental changes, we studied soil respiration, litter decomposition, and their relations to soil temperature and soil water content for 18-months (Aug. 2010–Jan. 2012) in three different-aged Pinus massoniana forests in the Three Gorges Reservoir Area, China. Across the experimental period, the mean total soil respiration and litter respiration were 1.94 and 0.81, 2.00 and 0.60, 2.19 and 0.71 µmol CO2 m−2 s−1, and the litter dry mass remaining was 57.6%, 56.2% and 61.3% in the 20-, 30-, and 46-year-old forests, respectively. We found that the temporal variations of soil respiration and litter decomposition rates can be well explained by soil temperature at 5 cm depth. Both the total soil respiration and litter respiration were significantly positively correlated with the litter decomposition rates. The mean contribution of the litter respiration to the total soil respiration was 31.0%–45.9% for the three different-aged forests. The present study found that the total soil respiration was not significantly affected by forest age when P. masonniana stands exceed a certain age (e.g. >20 years old), but it increased significantly with increased soil temperature. Hence, forest management strategies need to protect the understory vegetation to limit soil warming, in order to reduce the CO2 emission under the currently rapid global warming. The contribution of litter decomposition to the total soil respiration varies across spatial and temporal scales. This indicates the need for separate consideration of soil and litter respiration when assessing the climate impacts on forest carbon cycling. PMID:25004164

  14. 78 FR 18535 - Respirator Certification Fees

    Science.gov (United States)

    2013-03-27

    ... facepiece respirators. The North American respiratory protection market generated revenues around $1,830 million in 2007, the most recent data available.\\4\\ A summary of market segmentation, by respirator type... management. Of the U.S. respirator market of products approved by NIOSH, approximately 35 percent of approval...

  15. Does Short-term Litter Input Manipulation Affect Soil Respiration and the Carbon-isotopic Signature of Soil Respired CO2

    Science.gov (United States)

    Cheng, X.; Wu, J.

    2016-12-01

    Global change greatly alters the quality and quantity of plant litter inputs to soils, and further impacts soil organic matter (SOM) dynamics and soil respiration. However, the process-based understanding of how soil respiration may change with future shift in litter input is not fully understood. The Detritus Input and Removal Treatment (DIRT) experiment was conducted in coniferous forest (Platycladus orientalis (Linn.) Franco) ecosystem of central China to investigate the impact of above- and belowground litter input on soil respiration and the carbon-isotopic signature of soil respired CO2. Short-term (1-2 years) litter input manipulation significantly affected soil respiration, based on annual flux values, soil respiration was 31.9%, 20.5% and 37.2% lower in no litter (NL), no root (NR) and no input (NRNL), respectively, compared to control (CK). Whereas double litter (DL) treatment increased soil respiration by 9.1% compared to CK. The recalcitrance index of carbon (RIC) and the relative abundance of fungi increased under litter removal or root exclusion treatment (NL, NR and NRNL) compared to CK. Basal soil respiration was positively related to liable C and microbial biomass and negatively related to RIC and fungi to bacteria (F: B) ratio. The carbon-isotopic signature of soil respired CO2 enriched under litter removal and no input treatment, and slightly depleted under litter addition treatment compared to CK. Our results suggest that short-term litter input manipulation can affect the soil respiration by altering substrate availability and microbial community structure, and also impact the carbon-isotopic signature of soil respired CO2 possibly duo to change in the component of soil respiration and soil microclimate.

  16. A mechanical breathing simulator for respirator test

    International Nuclear Information System (INIS)

    Murata, Mikio; Ikezawa, Yoshio; Yoshida, Yoshikazu

    1976-01-01

    A mechanical breathing simulator has been developed to produce the human respiration for use in respirator test. The respirations were produced through the strokes of piston controlled by a rockerarm with adjustable fulcrum. The respiration rate was governed by motor-speed control, independent of the tidal volume achieved by adjustment of the piston stroke. By the breather, the simulated respirations for work rate 0, 208, 415, 622 and 830 kg-m/min could be produced through the typical dummy head. (auth.)

  17. Respirators: Supervisors Self-Study #43442

    Energy Technology Data Exchange (ETDEWEB)

    Chochoms, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-20

    This course, Respirators: Supervisors Self-Study (#43442), addresses training requirements for supervisors of respirator wearers as specified by the American National Standard Institute (ANSI) Standard for Respiratory Protection, ANSI Z88.2, and as incorporated by reference in the Department of Energy (DOE) Worker Health and Safety Rule, 10 Code of Federal Regulations (CFR) 851. This course also presents the responsibilities of supervisors of respirator wearers at Los Alamos National Laboratory (LANL).

  18. Roots affect the response of heterotrophic soil respiration to temperature in tussock grass microcosms.

    Science.gov (United States)

    Graham, Scott L; Millard, Peter; Hunt, John E; Rogers, Graeme N D; Whitehead, David

    2012-07-01

    While the temperature response of soil respiration (R(S)) has been well studied, the partitioning of heterotrophic respiration (R(H)) by soil microbes from autotrophic respiration (R(A)) by roots, known to have distinct temperature sensitivities, has been problematic. Further complexity stems from the presence of roots affecting R(H), the rhizosphere priming effect. In this study the short-term temperature responses of R(A) and R(H) in relation to rhizosphere priming are investigated. Temperature responses of R(A), R(H) and rhizosphere priming were assessed in microcosms of Poa cita using a natural abundance δ(13)C discrimination approach. The temperature response of R(S) was found to be regulated primarily by R(A), which accounted for 70 % of total soil respiration. Heterotrophic respiration was less sensitive to temperature in the presence of plant roots, resulting in negative priming effects with increasing temperature. The results emphasize the importance of roots in regulating the temperature response of R(S), and a framework is presented for further investigation into temperature effects on heterotrophic respiration and rhizosphere priming, which could be applied to other soil and vegetation types to improve models of soil carbon turnover.

  19. Determination of exposure to respirable quartz in the stone crushing units at Azendarian-West of Iran.

    Science.gov (United States)

    Bahrami, Abdul Rahman; Golbabai, Faridah; Mahjub, Hossien; Qorbani, Farshid; Aliabadi, Mohsan; Barqi, Mohamadali

    2008-08-01

    The purpose of this study is to describe the personal exposure to respirable dust and quartz and in stone crushing units located at west of Iran. A size of 40 personal samples and 40 stationary samples were obtained and analysis was done by X-ray diffraction (XRD). The results of personal sampling were shown the concentrations of respirable dust exposure level in workers of process, hopper and drivers were 1.90, 2.22, 1.41 times greater than Occupational Safety and Health Administration permissible exposure limit (OSHA PEL). The average value of total dust and respirable dust emission from stationary sources was 9.46 mg/m(3), 1.24 mg/m(3) respectively, showing that 13.8 % of total dust is respirable. The efficiency of local exhaust ventilation (LEV) to control of particles inside of industrial units was greater than 99%. It is concluded from this research the particulate generated from stone crushing activities contain a significant amount of respirable particle. The amount of free silica in stone quartz is 85 to 97 percent that emission of particles effect to health workers. LEV has important effect in the removal of silica particles in stone crushing units. The worker of hoppers still exposed to silica more than standard limits.

  20. Effect of typhoon disturbance on soil respiration dynamic in a tropical broadleaves plantation in southern Taiwan

    Science.gov (United States)

    Chiang, Po-Neng; Yu, Jui-Chu; Lai, Yen-Jen

    2017-04-01

    Global forests contain 69% of total carbon stored in forest soil and litter. But the carbon storage ability and release rate of warming gases of forest soil also affect global climate change. Reforestation is one of the best solutions to mitigate warming gases release and to store in soil. Typhoon is one of the most hazards to disturb forest ecosystem and change carbon cycle. Typhoon disturbance is also affect soil carbon cycle such as soil respiration, carbon storage. Therefore, the objective of this study is to clarify the effect of typhoon disturbance on soil respiration dynamic in a tropical broadleaves plantation in southern Taiwan. Fourteen broadleaved tree species were planted in 2002-2005. Twelves continuous soil respiration chambers was divided two treatments (trench and non-trench) and observed since 2011 to 2014. The soil belongs to Entisol with over 60% of sandstone. The soil pH is 5.5 with low base cations because of high sand percentage. Forest biometric such as tree high, DBH, litterfall was measured in 2011-2014. Data showed that the accumulation amount of litterfall was highest in December to February and lowest in June. Soil respiration was related with season variation in research site. Soil temperature showed significantly exponential related with soil respiration in research site (p<0.001).However, soil respiration showed significantly negative relationship with total amount of litterfall (p<0.001), suggesting that the tree was still young and did not reach crown closure.

  1. Soil respiration sensitivities to water and temperature in a revegetated desert

    Science.gov (United States)

    Zhang, Zhi-Shan; Dong, Xue-Jun; Xu, Bing-Xin; Chen, Yong-Le; Zhao, Yang; Gao, Yan-Hong; Hu, Yi-Gang; Huang, Lei

    2015-04-01

    Soil respiration in water-limited ecosystems is affected intricately by soil water content (SWC), temperature, and soil properties. Eight sites on sand-fixed dunes that revegetated in different years since 1950s, with several topographical positions and various biological soil crusts (BSCs) and soil properties, were selected, as well as a moving sand dune (MSD) and a reference steppe in the Tengger Desert of China. Intact soil samples of 20 cm in depth were taken and incubated randomly at 12 levels of SWC (0 to 0.4 m3 m-3) and at 9 levels of temperature (5 to 45°C) in a growth chamber; additionally, cryptogamic and microbial respirations (RM) were measured. Total soil respiration (RT, including cryptogamic, microbial, and root respiration) was measured for 2 years at the MSD and five sites of sand-fixed dunes. The relationship between RM and SWC under the optimal SWC condition (0.25 m3 m-3) is linear, as is the entire range of RT and SWC. The slope of linear function describes sensitivity of soil respiration to water (SRW) and reflects to soil water availability, which is related significantly to soil physical properties, BSCs, and soil chemical properties, in decreasing importance. Inversely, Q10 for RM is related significantly to abovementioned factors in increasing importance. However, Q10 for RT and respiration rate at 20°C are related significantly to soil texture and depth of BSCs and subsoil only. In conclusion, through affecting SRW, soil physical properties produce significant influences on soil respiration, especially for RT. This indicates that a definition of the biophysical meaning of SRW is necessary, considering the water-limited and coarse-textured soil in most desert ecosystems.

  2. Precipitation Regime Shift Enhanced the Rain Pulse Effect on Soil Respiration in a Semi-Arid Steppe

    Science.gov (United States)

    Yan, Liming; Chen, Shiping; Xia, Jianyang; Luo, Yiqi

    2014-01-01

    The effect of resource pulses, such as rainfall events, on soil respiration plays an important role in controlling grassland carbon balance, but how shifts in long-term precipitation regime regulate rain pulse effect on soil respiration is still unclear. We first quantified the influence of rainfall event on soil respiration based on a two-year (2006 and 2009) continuously measured soil respiration data set in a temperate steppe in northern China. In 2006 and 2009, soil carbon release induced by rainfall events contributed about 44.5% (83.3 g C m−2) and 39.6% (61.7 g C m−2) to the growing-season total soil respiration, respectively. The pulse effect of rainfall event on soil respiration can be accurately predicted by a water status index (WSI), which is the product of rainfall event size and the ratio between antecedent soil temperature to moisture at the depth of 10 cm (r 2 = 0.92, Psoil temperature/moisture ratio which is usually associated with longer dry spells. We then analyzed a long-term (1953–2009) precipitation record in the experimental area. We found both the extreme heavy rainfall events (>40 mm per event) and the long dry-spells (>5 days) during the growing seasons increased from 1953–2009. It suggests the shift in precipitation regime has increased the contribution of rain pulse effect to growing-season total soil respiration in this region. These findings highlight the importance of incorporating precipitation regime shift and its impacts on the rain pulse effect into the future predictions of grassland carbon cycle under climate change. PMID:25093573

  3. Leaf Litterfall and Decomposition of Polylepis reticulata in the Treeline of the Ecuadorian Andes

    Directory of Open Access Journals (Sweden)

    Juan Pinos

    2017-02-01

    Full Text Available Leaf litterfall contributes significantly to carbon fluxes in forests. A crucial open question for the sustainability of mountain forests is how climate change will affect this and other carbon fluxes (eg photosynthesis and respiration. Leaf litterfall and decomposition of Polylepis reticulata, an endemic species of the Andes, were analyzed during a period of 1 year at 6 experimental plots located in the Andean páramo between 3700 and 3900 m above sea level in Cajas National Park, Ecuador. Litterfall was collected in each plot using 5 randomly distributed traps. Every trap had a 40-cm diameter (0.125 m2 and was suspended 0.8 to 1.0 m above the ground. The decomposition rate of the leaf litter was analyzed using litter bags. Eighteen bags with approximately 20 g of dry litter were placed in the litter layer in each experimental plot and collected 30, 60, 90, 150, 210, 300, and 365 days after they were installed. The mean annual litterfall recorded was 3.77 Mg ha−1, representing 51% of the leaf biomass present in the canopy, so the leaf life span of P. reticulata in Cajas National Park is 1.98 years. Litterfall occurred all year, with no significant seasonal pattern. The mean decomposition rate (k obtained for this study period was 0.38 year−1. This study contributes to the information gap on litterfall and decomposition in natural forests located at the highest elevations in the world.

  4. Impact of carbohydrate supply on stem growth, wood and respired CO{sub 2} {delta}{sup 13}C : assessment by experimental girdling

    Energy Technology Data Exchange (ETDEWEB)

    Maunoury-Danger, F. [Paris-Sud Univ., Orsay Cedex (France). Laboratoire Ecologie, Systematique et Evolution; Centre National de la Recherche Scientifique, Orsay CEDEX (France); AgroParisTech, Paris (France); Paul Verlaine-Metz Univ., Metz (France). Laboratoire des Interactions Ecotoxicologie Biodiversite Ecosystemes; Fresneau, C.; Eglin, T.; Berveiller, D.; Francois, C.; Damesin, C. [Paris-Sud Univ., Orsay Cedex (France). Laboratoire Ecologie, Systematique et Evolution; Centre National de la Recherche Scientifique, Orsay CEDEX (France); AgroParisTech, Paris (France); Lelarge-Trouverie, C. [Paris-Sud Univ., Orsay Cedex (France). Inst. de Biotechnologie des Plantes, Plateforme Metabolisme-Metabolome

    2010-07-15

    In trees, carbohydrate storage and remobilization may affect the carbon isotope signals of sugars exported from leaves, tree organic matter and respired carbon dioxide (CO{sub 2}). This study characterized the impact of a change in the carbon (C) source used for stem functioning on the {delta}{sup 13} C of stem organic matter and respired CO{sub 2}. Girdling experiments were carried out on 2-year old oaks that consisted in removing the bark and phloem around the stem so that the sap would cease to flow. The stem was therefore forced to use its own C reserves to maintain metabolic activity. Trees were girdled at 3 different periods, notably just after budburst, during stem growth, and just after cessation of stem radial growth. Stem radial growth and respiration rate were measured throughout the year. Other measured variables included {delta}{sup 13} C of respired CO{sub 2} and contents of starch and water-soluble fraction in stems and leaves. The study showed that girdling stopped growth, even early in the growing season, leading to a decrease in stem CO{sub 2} efflux. The study demonstrated that leaf carbohydrate supply versus reserve use could be an important factor controlling stem growth and {delta}{sup 13} C of both ring and stem CO{sub 2} efflux. 69 refs., 3 tabs., 5 figs.

  5. Peach leaf responses to soil and cement dust pollution.

    Science.gov (United States)

    Maletsika, Persefoni A; Nanos, George D; Stavroulakis, George G

    2015-10-01

    Dust pollution can negatively affect plant productivity in hot, dry and with high irradiance areas during summer. Soil or cement dust were applied on peach trees growing in a Mediterranean area with the above climatic characteristics. Soil and cement dust accumulation onto the leaves decreased the photosynthetically active radiation (PAR) available to the leaves without causing any shade effect. Soil and mainly cement dust deposition onto the leaves decreased stomatal conductance, photosynthetic and transpiration rates, and water use efficiency due possibly to stomatal blockage and other leaf cellular effects. In early autumn, rain events removed soil dust and leaf functions partly recovered, while cement dust created a crust partially remaining onto the leaves and causing more permanent stress. Leaf characteristics were differentially affected by the two dusts studied due to their different hydraulic properties. Leaf total chlorophyll decreased and total phenol content increased with dust accumulation late in the summer compared to control leaves due to intense oxidative stress. The two dusts did not cause serious metal imbalances to the leaves, except of lower leaf K content.

  6. Mitochondrial respiration is sensitive to cytoarchitectural breakdown.

    Science.gov (United States)

    Kandel, Judith; Angelin, Alessia A; Wallace, Douglas C; Eckmann, David M

    2016-11-07

    An abundance of research suggests that cellular mitochondrial and cytoskeletal disruption are related, but few studies have directly investigated causative connections between the two. We previously demonstrated that inhibiting microtubule and microfilament polymerization affects mitochondrial motility on the whole-cell level in fibroblasts. Since mitochondrial motility can be indicative of mitochondrial function, we now further characterize the effects of these cytoskeletal inhibitors on mitochondrial potential, morphology and respiration. We found that although they did not reduce mitochondrial inner membrane potential, cytoskeletal toxins induced significant decreases in basal mitochondrial respiration. In some cases, basal respiration was only affected after cells were pretreated with the calcium ionophore A23187 in order to stress mitochondrial function. In most cases, mitochondrial morphology remained unaffected, but extreme microfilament depolymerization or combined intermediate doses of microtubule and microfilament toxins resulted in decreased mitochondrial lengths. Interestingly, these two particular exposures did not affect mitochondrial respiration in cells not sensitized with A23187, indicating an interplay between mitochondrial morphology and respiration. In all cases, inducing maximal respiration diminished differences between control and experimental groups, suggesting that reduced basal respiration originates as a largely elective rather than pathological symptom of cytoskeletal impairment. However, viability experiments suggest that even this type of respiration decrease may be associated with cell death.

  7. 42 CFR 84.197 - Respirator containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.197... Cartridge Respirators § 84.197 Respirator containers; minimum requirements. Respirators shall be equipped with a substantial, durable container bearing markings which show the applicant's name, the type and...

  8. 42 CFR 84.174 - Respirator containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.174... Air-Purifying Particulate Respirators § 84.174 Respirator containers; minimum requirements. (a) Except..., durable container bearing markings which show the applicant's name, the type of respirator it contains...

  9. Metabolic origin of the {delta}{sup 13}C of respired CO{sub 2} in roots of Phaseolus vulgaris

    Energy Technology Data Exchange (ETDEWEB)

    Bathellier, C.; Tcherkez, G.; Cornic, G.; Ghashghaie, J. [Laboratoire d' Ecologie, Systematique et Evolution - ESE, CNRS-UMR 8079 - IFR 87, Batiment 362, Universite Paris-Sud, 91405-Orsay Cedex (France); Tcherkez, G. [Plateforme Metabolisme-Metabolome, IFR87 La Plante et son Environnement, Institut de Biotechnologie des Plantes, Batiment 630, Universite Paris-Sud, 91405-Orsay Cedex (France); Bligny, R.; Gout, E. [Laboratoire de Physiologie Cellulaire Vegetale CEA-Grenoble 17, rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2009-07-01

    - Root respiration is a major contributor to soil CO{sub 2} efflux, and thus an important component of ecosystem respiration. But its metabolic origin, in relation to the carbon isotope composition ({delta}{sup 13}C), remains poorly understood. - Here, {sup 13}C analysis was conducted on CO{sub 2} and metabolites under typical conditions or under continuous darkness in French bean (Phaseolus vulgaris) roots. {sup 13}C contents were measured either under natural abundance or following pulse-chase labeling with {sup 13}C-enriched glucose or pyruvate, using isotope ratio mass spectrometer (IRMS) and nuclear magnetic resonance (NMR) techniques. - In contrast to leaves, no relationship was found between the respiratory quotient and the {delta}{sup 13}C of respired CO{sub 2}, which stayed constant at a low value (c. -27.5 per thousand) under continuous darkness. With labeling experiments, it is shown that such a pattern is explained by the {sup 13}C-depleting effect of the pentose phosphate pathway; and the involvement of the Krebs cycle fueled by either the glycolytic input or the lipid/protein recycling. The anaplerotic phosphoenolpyruvate carboxylase (PEPc) activity sustained glutamic acid (Glu) synthesis, with no net effect on respired CO{sub 2}. - These results indicate that the root {delta}{sup 13}C signal does not depend on the availability of root respiratory substrates and it is thus plausible that, unless the {sup 13}C photosynthetic fractionation varies at the leaf level, the root {delta}{sup 13}C signal hardly changes under a range of natural environmental conditions. (authors)

  10. Leaf gas exchange characteristics of three neotropical mangrove species in response to varying hydroperiod

    Science.gov (United States)

    Krauss, Ken W.; Twilley, Robert R.; Doyle, Thomas W.; Gardiner, Emile S.

    2006-01-01

    We determined how different hydroperiods affected leaf gas exchange characteristics of greenhouse-grown seedlings (2002) and saplings (2003) of the mangrove species Avicennia germinans (L.) Stearn., Laguncularia racemosa (L.) Gaertn. f., and Rhizophora mangle L. Hydroperiod treatments included no flooding (unflooded), intermittent flooding (intermittent), and permanent flooding (flooded). Plants in the intermittent treatment were measured under both flooded and drained states and compared separately. In the greenhouse study, plants of all species maintained different leaf areas in the contrasting hydroperiods during both years. Assimilation–light response curves indicated that the different hydroperiods had little effect on leaf gas exchange characteristics in either seedlings or saplings. However, short-term intermittent flooding for between 6 and 22 days caused a 20% reduction in maximum leaf-level carbon assimilation rate, a 51% lower light requirement to attain 50% of maximum assimilation, and a 38% higher demand from dark respiration. Although interspecific differences were evident for nearly all measured parameters in both years, there was little consistency in ranking of the interspecific responses. Species by hydroperiod interactions were significant only for sapling leaf area. In a field study, R. mangle saplings along the Shark River in the Everglades National Park either demonstrated no significant effect or slight enhancement of carbon assimilation and water-use efficiency while flooded. We obtained little evidence that contrasting hydroperiods affect leaf gas exchange characteristics of mangrove seedlings or saplings over long time intervals; however, intermittent flooding may cause short-term depressions in leaf gas exchange. The resilience of mangrove systems to flooding, as demonstrated in the permanently flooded treatments, will likely promote photosynthetic and morphological adjustment to slight hydroperiod shifts in many settings..

  11. 42 CFR 84.134 - Respirator containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.134... Respirators § 84.134 Respirator containers; minimum requirements. Supplied-air respirators shall be equipped with a substantial, durable container bearing markings which show the applicant's name, the type and...

  12. [A review of progress of real-time tumor tracking radiotherapy technology based on dynamic multi-leaf collimator].

    Science.gov (United States)

    Liu, Fubo; Li, Guangjun; Shen, Jiuling; Li, Ligin; Bai, Sen

    2017-02-01

    While radiation treatment to patients with tumors in thorax and abdomen is being performed, further improvement of radiation accuracy is restricted by the tumor intra-fractional motion due to respiration. Real-time tumor tracking radiation is an optimal solution to tumor intra-fractional motion. A review of the progress of real-time dynamic multi-leaf collimator(DMLC) tracking is provided in the present review, including DMLC tracking method, time lag of DMLC tracking system, and dosimetric verification.

  13. Stand-scale soil respiration estimates based on chamber methods in a Bornean tropical rainforest

    Science.gov (United States)

    Kume, T.; Katayama, A.; Komatsu, H.; Ohashi, M.; Nakagawa, M.; Yamashita, M.; Otsuki, K.; Suzuki, M.; Kumagai, T.

    2009-12-01

    This study was undertaken to estimate stand-scale soil respiration in an aseasonal tropical rainforest on Borneo Island. To this aim, we identified critical and practical factors explaining spatial variations in soil respiration based on the soil respiration measurements conducted at 25 points in a 40 × 40 m subplot of a 4 ha study plot for five years in relation to soil, root, and forest structural factors. Consequently, we found significant positive correlation between the soil respiration and forest structural parameters. The most important factor was the mean DBH within 6 m of the measurement points, which had a significant linear relationship with soil respiration. Using the derived linear regression and an inventory dataset, we estimated the 4 ha-scale soil respiration. The 4 ha-scale estimation (6.0 μmol m-2 s-1) was nearly identical to the subplot scale measurements (5.7 μmol m-2 s-1), which were roughly comparable to the nocturnal CO2 fluxes calculated using the eddy covariance technique. To confirm the spatial representativeness of soil respiration estimates in the subplot, we performed variogram analysis. Semivariance of DBH(6) in the 4 ha plot showed that there was autocorrelation within the separation distance of about 20 m, and that the spatial dependence was unclear at a separation distance of greater than 20 m. This ascertained that the 40 × 40 m subplot could represent the whole forest structure in the 4 ha plot. In addition, we discuss characteristics of the stand-scale soil respiration at this site by comparing with those of other forests reported in previous literature in terms of the soil C balance. Soil respiration at our site was noticeably greater, relative to the incident litterfall amount, than soil respiration in other tropical and temperate forests probably owing to the larger total belowground C allocation by emergent trees. Overall, this study suggests the arrangement of emergent trees and their bellow ground C allocation could be

  14. An analytical approach for optimizing the leaf design of a multi-leaf collimator in a linear accelerator

    International Nuclear Information System (INIS)

    Topolnjak, R; Heide, U A van der

    2008-01-01

    In this study, we present an analytical approach for optimizing the leaf design of a multi-leaf collimator (MLC) in a linear accelerator. Because leaf designs vary between vendors, our goal is to characterize and quantify the effects of different compromises which have to be made between performance parameters. Subsequently, an optimal leaf design for an earlier proposed six-bank MLC which combines a high-resolution field-shaping ability with a large field size is determined. To this end a model of the linac is created that includes the following parameters: the source size, the maximum field size, the distance between source and isocenter, and the leaf's design parameters. First, the optimal radius of the leaf tip was found. This optimum was defined by the requirement that the fluence intensity should fall from 80% of the maximum value to 20% in a minimal distance, defining the width of the fluence penumbra. A second requirement was that this penumbra width should be constant when a leaf moves from one side of the field to the other. The geometric, transmission and total penumbra width (80-20%) were calculated depending on the design parameters. The analytical model is in agreement with Elekta, Varian and Siemens collimator designs. For leaves thinner than 4 cm, the transmission penumbra becomes dominant, and for leaves close to the source the geometric penumbra plays a role. Finally, by choosing the leaf thickness of 3.5 cm, 4 cm and 5 cm from the lowest to the highest bank, respectively, an optimal leaf design for a six-bank MLC is achieved

  15. Accumulation of three different sizes of particulate matter on plant leaf surfaces: Effect on leaf traits

    Directory of Open Access Journals (Sweden)

    Chen Xiaoping

    2015-01-01

    Full Text Available Plants not only improve air quality by adsorbing particulate matter (PM on leaf surfaces but can also be affected by their accumulation. In this study, a field investigation was performed in Wuhan, China, into the relationship between seven leaf traits and the accumulation of three different sizes of PM (PM11, PM2.5 and PM0.2 on leaves. The retention abilities of plant leaves with respect to the three sizes of PM differed significantly at different sites and species. The average PM retention capabilities of plant leaves and specific leaf area (SLA were significantly greater in a seriously polluted area, whereas the average values of chlorophyll a (Chl a, chlorophyll b (Chl b, total chlorophyll, carotenoid, pH and relative water content (RWC were greater at the control site. SLA significantly positively correlated with the size of PM, but Chl a, Chl b, total chlorophyll, RWC significantly negatively correlated with the size of PM, whereas the pH did not correlate significantly with the the PM fractions. Additionally, SLA was found to be affected by large particles (PM11, p<0.01; PM2.5 had a more obvious effect on plant leaf traits than the other PM (p<0.05. Overall, the findings from this study provide useful information regarding the selection of plants to reduce atmospheric pollution.

  16. Characterization of small-to-medium head-and-face dimensions for developing respirator fit test panels and evaluating fit of filtering facepiece respirators with different faceseal design

    Science.gov (United States)

    Lin, Yi-Chun

    2017-01-01

    A respirator fit test panel (RFTP) with facial size distribution representative of intended users is essential to the evaluation of respirator fit for new models of respirators. In this study an anthropometric survey was conducted among youths representing respirator users in mid-Taiwan to characterize head-and-face dimensions key to RFTPs for application to small-to-medium facial features. The participants were fit-tested for three N95 masks of different facepiece design and the results compared to facial size distribution specified in the RFTPs of bivariate and principal component analysis design developed in this study to realize the influence of facial characteristics to respirator fit in relation to facepiece design. Nineteen dimensions were measured for 206 participants. In fit testing the qualitative fit test (QLFT) procedures prescribed by the U.S. Occupational Safety and Health Administration were adopted. As the results show, the bizygomatic breadth of the male and female participants were 90.1 and 90.8% of their counterparts reported for the U.S. youths (P < 0.001), respectively. Compared to the bivariate distribution, the PCA design better accommodated variation in facial contours among different respirator user groups or populations, with the RFTPs reported in this study and from literature consistently covering over 92% of the participants. Overall, the facial fit of filtering facepieces increased with increasing facial dimensions. The total percentages of the tests wherein the final maneuver being completed was “Moving head up-and-down”, “Talking” or “Bending over” in bivariate and PCA RFTPs were 13.3–61.9% and 22.9–52.8%, respectively. The respirators with a three-panel flat fold structured in the facepiece provided greater fit, particularly when the users moved heads. When the facial size distribution in a bivariate RFTP did not sufficiently represent petite facial size, the fit testing was inclined to overestimate the general fit

  17. How Does Temperature Impact Leaf Size and Shape in Four Woody Dicot Species? Testing the Assumptions of Leaf Physiognomy-Climate Models

    Science.gov (United States)

    McKee, M.; Royer, D. L.

    2017-12-01

    The physiognomy (size and shape) of fossilized leaves has been used to reconstruct the mean annual temperature of ancient environments. Colder temperatures often select for larger and more abundant leaf teeth—serrated edges on leaf margins—as well as a greater degree of leaf dissection. However, to be able to accurately predict paleotemperature from the morphology of fossilized leaves, leaves must be able to react quickly and in a predictable manner to changes in temperature. We examined the extent to which temperature affects leaf morphology in four tree species: Carpinus caroliniana, Acer negundo, Ilex opaca, and Ostrya virginiana. Saplings of these species were grown in two growth cabinets under contrasting temperatures (17 and 25 °C). Compared to the cool treatment, in the warm treatment Carpinus caroliniana leaves had significantly fewer leaf teeth and a lower ratio of total number of leaf teeth to internal perimeter; and Acer negundo leaves had a significantly lower feret diameter ratio (a measure of leaf dissection). In addition, a two-way ANOVA tested the influence of temperature and species on leaf physiognomy. This analysis revealed that all plants, regardless of species, tended to develop more highly dissected leaves with more leaf teeth in the cool treatment. Because the cabinets maintained equivalent moisture, humidity, and CO2 concentration between the two treatments, these results demonstrate that these species could rapidly adapt to changes in temperature. However, not all of the species reacted identically to temperature changes. For example, Acer negundo, Carpinus caroliniana, and Ostrya virginiana all had a higher number of total teeth in the cool treatment compared to the warm treatment, but the opposite was true for Ilex opaca. Our work questions a fundamental assumption common to all models predicting paleotemperature from the physiognomy of fossilized leaves: a given climate will inevitably select for the same leaf physiognomy

  18. Annual ecosystem respiration variability of alpine peatland on the eastern Qinghai-Tibet Plateau and its controlling factors.

    Science.gov (United States)

    Peng, Haijun; Hong, Bing; Hong, Yetang; Zhu, Yongxuan; Cai, Chen; Yuan, Lingui; Wang, Yu

    2015-09-01

    Peatlands are widely developed in the eastern Qinghai-Tibet Plateau, but little is known about carbon budgets for these alpine peatland ecosystems. In this study, we used an automatic chamber system to measure ecosystem respiration in the Hongyuan peatland, which is located in the eastern Qinghai-Tibet Plateau. Annual ecosystem respiration measurements showed a typical seasonal pattern, with the peak appearing in June. The highest respiration was 10.43 μmol CO2/m(2)/s, and the lowest was 0.20 μmol CO2/m(2)/s. The annual average ecosystem respiration was 2.06 μmol CO2/m(2)/s. The total annual respiration was 599.98 g C/m(2), and respiration during the growing season (from May to September) accounted for 78 % of the annual sum. Nonlinear regression revealed that ecosystem respiration has a significant exponential correlation with soil temperature at 10-cm depth (R (2) = 0.98). The Q 10 value was 3.90, which is far higher than the average Q 10 value of terrestrial ecosystems. Ecosystem respiration had an apparent diurnal variation pattern in growing season, with peaks and valleys appearing at approximately 14:00 and 10:00, respectively, which could be explained by soil temperature and soil water content variation at 10-cm depth.

  19. Betel leaf in stoma care.

    Science.gov (United States)

    Banu, Tahmina; Talukder, Rupom; Chowdhury, Tanvir Kabir; Hoque, Mozammel

    2007-07-01

    Construction of a stoma is a common procedure in pediatric surgical practice. For care of these stomas, commercially available devices such as ostomy bag, either disposable or of longer duration are usually used. These are expensive, particularly in countries like Bangladesh, and proper-sized ones are not always available. We have found an alternative for stoma care, betel leaf, which is suitable for Bangladeshis. We report the outcome of its use. After construction of stoma, at first zinc oxide paste was applied on the peristomal skin. A betel leaf with shiny, smooth surface outwards and rough surface inwards was put over the stoma with a hole made in the center according to the size of stoma. Another intact leaf covers the stomal opening. When bowel movement occurs, the overlying intact leaf was removed and the fecal matter was washed away from both. The leaves were reused after cleaning. Leaves were changed every 2 to 3 days. From June 1998 to December 2005, in the department of pediatric surgery, Chittagong Medical College and Hospital, Chittagong, Bangladesh, a total of 623 patients had exteriorization of bowel. Of this total, 495 stomas were cared for with betel leaves and 128 with ostomy bags. Of 623 children, 287 had sigmoid colostomy, 211 had transverse colostomy, 105 had ileostomy, and 20 had jejunostomy. Of the 495 children under betel leaf stoma care, 13 patients (2.6%) developed skin excoriation. There were no allergic reactions. Of the 128 patients using ostomy bag, 52 (40.65%) had skin excoriation. Twenty-four (18.75%) children developed some allergic reactions to adhesive. Monthly costs for betel leaves were 15 cents (10 BDT), whereas ostomy bags cost about US$24. In the care of stoma, betel leaves are cheap, easy to handle, nonirritant, and nonallergic.

  20. Changes in oxidative properties of Kalanchoe blossfeldiana leaf mitochondria during development of Crassulacean acid metabolism.

    Science.gov (United States)

    Rustin, P; Queiroz-Claret, C

    1985-06-01

    Kalanchoe blossfeldiana plants grown under long days (16 h light) exhibit a C3-type photosynthetic metabolism. Switching to short days (9 h light) leads to a gradual development of Crassulacean acid metabolism (CAM). Under the latter conditions, dark CO2 fixation produces large amounts of malate. During the first hours of the day, malate is rapidly decarboxylated into pyruvate through the action of a cytosolic NADP(+)-or a mitochondrial NAD(+)-dependent malic enzyme. Mitochondria were isolated from leaves of plants grown under long days or after treatment by an increasing number of short days. Tricarboxylic acid cycle intermediates as well as exogenous NADH and NADPH were readily oxidized by mitochondria isolated from the two types of plants. Glycine, known to be oxidized by C3-plant mitochondria, was still oxidized after CAM establishment. The experiments showed a marked parallelism in the increase of CAM level and the increase in substrate-oxidation capacity of the isolated mitochondria, particularly the capacity to oxidize malate in the presence of cyanide. These simultaneous variations in CAM level and in mitochondrial properties indicate that the mitochondrial NAD(+)-malic enzyme could account at least for a part of the oxidation of malate. The studies of whole-leaf respiration establish that mitochondria are implicated in malate degradation in vivo. Moreover, an increase in cyanide resistance of the leaf respiration has been observed during the first daylight hours, when malate was oxidized to pyruvate by cytosolic and mitochondrial malic enzymes.

  1. Spatial and temporal variation of CO2 efflux along a disturbance gradient in a miombo woodland in Western Zambia

    Directory of Open Access Journals (Sweden)

    M. M. Mukelabai

    2011-01-01

    Full Text Available Carbon dioxide efflux from the soil surface was measured over a period of several weeks within a heterogeneous Brachystegia spp. dominated miombo woodland in Western Zambia. The objectives were to examine spatial and temporal variation of soil respiration along a disturbance gradient from a protected forest reserve to a cut, burned, and grazed area outside, and to relate the flux to various abiotic and biotic drivers. The highest daily mean fluxes (around 12 μmol CO2 m−2 s−1 were measured in the protected forest in the wet season and lowest daily mean fluxes (around 1 μmol CO2 m−2 s−1 in the most disturbed area during the dry season. Diurnal variation of soil respiration was closely correlated with soil temperature. The combination of soil water content and soil temperature was found to be the main driving factor at seasonal time scale. There was a 75% decrease in soil CO2 efflux during the dry season and a 20% difference in peak soil respiratory flux measured in 2008 and 2009. Spatial variation of CO2 efflux was positively related to total soil carbon content in the undisturbed area but not at the disturbed site. Coefficients of variation of efflux rates between plots decreased towards the core zone of the protected forest reserve. Normalized soil respiration values did not vary significantly along the disturbance gradient. Spatial variation of respiration did not show a clear distinction between the disturbed and undisturbed sites and could not be explained by variables such as leaf area index. In contrast, within plot variability of soil respiration was explained by soil organic carbon content. Three different approaches to calculate total ecosystem respiration (Reco from eddy covariance measurements were compared to two bottom-up estimates of Reco obtained from chambers measurements of soil- and leaf respiration which differed in the consideration of spatial heterogeneity. The consideration of spatial variability resulted only in

  2. Multileaf collimator leaf position verification and analysis for adaptive radiation therapy using a video-optical method

    Science.gov (United States)

    Sethna, Sohrab B.

    External beam radiation therapy is commonly used to eliminate and control cancerous tumors. High-energy beams are shaped to match the patient's specific tumor volume, whereby maximizing radiation dose to malignant cells and limiting dose to normal tissue. A multileaf collimator (MLC) consisting of multiple pairs of tungsten leaves is used to conform the radiation beam to the desired treatment field. Advanced treatment methods utilize dynamic MLC settings to conform to multiple treatment fields and provide intensity modulated radiation therapy (IMRT). Future methods would further increase conformity by actively tracking tumor motion caused by patient cardiac and respiratory motion. Leaf position quality assurance for a dynamic MLC is critical as variation between the planned and actual leaf positions could induce significant errors in radiation dose. The goal of this research project is to prototype a video-optical quality assurance system for MLC leaf positions. The system captures light-field images of MLC leaf sequences during dynamic therapy. Image acquisition and analysis software was developed to determine leaf edge positions. The mean absolute difference between QA prototype predicted and caliper measured leaf positions was found to be 0.6 mm with an uncertainty of +/- 0.3 mm. Maximum errors in predicted positions were below 1.0 mm for static fields. The prototype served as a proof of concept for quality assurance of future tumor tracking methods. Specifically, a lung tumor phantom was created to mimic a lung tumor's motion from respiration. The lung tumor video images were superimposed on MLC field video images for visualization and analysis. The toolbox is capable of displaying leaf position, leaf velocity, tumor position, and determining errors between planned and actual treatment fields for dynamic radiation therapy.

  3. How does warming affect carbon allocation, respiration and residence time in trees? An isotope tracer approach in a eucalypt

    Science.gov (United States)

    Pendall, E.; Drake, J. E.; Furze, M.; Barton, C. V.; Carillo, Y.; Richter, A.; Tjoelker, M. G.

    2017-12-01

    Climate warming has the potential to alter the balance between photosynthetic carbon assimilation and respiratory losses in forest trees, leading to uncertainty in predicting their future physiological functioning. In a previous experiment, warming decreased canopy CO2 assimilation (A) rates of Eucalyptus tereticornis trees, but respiration (R) rates were usually not significantly affected, due to physiological acclimation to temperature. This led to a slight increase in (R/A) and thus decrease in plant carbon use efficiency with climate warming. In contrast to carbon fluxes, the effect of warming on carbon allocation and residence time in trees has received less attention. We conducted a study to test the hypothesis that warming would decrease the allocation of C belowground owing to reduced cost of nutrient uptake. E. parramattensis trees were grown in the field in unique whole-tree chambers operated at ambient and ambient +3 °C temperature treatments (n=3 per treatment). We applied a 13CO2 pulse and followed the label in CO2 respired from leaves, roots, canopy and soil, in plant sugars, and in rhizosphere microbes over a 3-week period in conjunction with measurements of tree growth. The 9-m tall, 57 m3 whole-tree chambers were monitored for CO2 concentrations in independent canopy and below ground (root and soil) compartments; periodic monitoring of δ13C values in air in the compartments allowed us to quantify the amount of 13CO2 assimilated and respired by each tree. Warmed trees grew faster and assimilated more of the label than control trees, but the 13C allocation to canopy, root and soil respiration was not altered. However, warming appeared to reduce the residence time of carbon respired from leaves, and especially from roots and soil, indicating that autotrophic respiration has the potential to feedback to climate change. This experiment provides insights into how warming may affect the fate of assimilated carbon from the leaf to the ecosystem scale.

  4. Usefulness of radiation treatment planning allpied respiration factor for streotatic body radiation therapy in the lung cancer

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Sung Pil; Kim, Tae Hyung; So, Woon Young; Back, Geum Mun [Dept. of Medical Health Science, Graduate School, Kangwon National University, Chuncheon (Korea, Republic of)

    2016-12-15

    We are evaluated the usefulness of radiation treatment planning applied respiration factor for stereotactic body radiation therapy in the lung cancer. Four dimensional computed tomography images were obtained in 10 patients with lung cancer. The radiation treatment plans were established total lung volume according to respiration images (new method) and conventional method. We was analyzed in the lung volume, radiation absorbed dose of lung and main organs (ribs, tracheobronchus, esophagus, spinal cord) around the tumor, respectively. We were confirmed that lung volume and radiation absorbed dose of lung and main organs around the tumor deference according to applied respiration. In conclusion, radiation treatment planning applied respiration factor seems to be useful for stereotactic body radiation therapy in the lung cancer.

  5. The Contribution of Old Carbon to Respiration from Alaskan Tundra Following Permafrost Thaw

    Science.gov (United States)

    Schuur, E. A.; Vogel, J. G.; Crummer, K. G.; Lee, H.; Sickman, J. O.; Dutta, K.

    2007-12-01

    More than 450 Pg of soil carbon (C) has accumulated in high latitude ecosystems after the retreat of the last major ice sheets. Recent studies suggest that, due to climate warming, these ecosystems may no longer be accumulating C, and in some cases may be losing stored C to the atmosphere. We used radiocarbon measurements of carbon dioxide to detect the age of C respired from tussock tundra near Denali National Park, Alaska. At this tundra site, permafrost has been observed to warm and thaw over the past several decades, causing the ground surface to subside as ice volume in the soil decreased. We established three sites within this area that differed in vegetation and surface topography; both characteristics varied in relation to the degree of permafrost thaw. We made radiocarbon measurements of ecosystem respiration, incubations of soil organic matter, and incubations of above and belowground plant biomass to determine the age and isotopic value of C respired from these sites. Over the study period from 2004 to 2006, ecosystem respiration radiocarbon values averaged from +35‰ to +95‰ in different months across sites. For soil incubations, surface soil radiocarbon was elevated relative both to ecosystem respiration and the current atmospheric radiocarbon value, demonstrating the significant contribution from C fixed over the past years to several decades. The deeper soil, in contrast, had respiration isotope values that averaged below zero, reflecting the significant effect of radioactive decay on the isotope content of deeper soil layers. The plant and soil incubations were combined in a multi- source mixing model to determine probable contributions from these different sources to ecosystem respiration. Deep soil respiration generally averaged between 5-15% of total ecosystem respiration, but reached as high as 40% in some months. When aggregated across the growing season, the two sites undergoing more disturbance from permafrost thaw had on average 2-3 times

  6. Soil respiration and organic carbon dynamics with grassland conversions to woodlands in temperate china.

    Directory of Open Access Journals (Sweden)

    Wei Wang

    Full Text Available Soils are the largest terrestrial carbon store and soil respiration is the second-largest flux in ecosystem carbon cycling. Across China's temperate region, climatic changes and human activities have frequently caused the transformation of grasslands to woodlands. However, the effect of this transition on soil respiration and soil organic carbon (SOC dynamics remains uncertain in this area. In this study, we measured in situ soil respiration and SOC storage over a two-year period (Jan. 2007-Dec. 2008 from five characteristic vegetation types in a forest-steppe ecotone of temperate China, including grassland (GR, shrubland (SH, as well as in evergreen coniferous (EC, deciduous coniferous (DC and deciduous broadleaved forest (DB, to evaluate the changes of soil respiration and SOC storage with grassland conversions to diverse types of woodlands. Annual soil respiration increased by 3%, 6%, 14%, and 22% after the conversion from GR to EC, SH, DC, and DB, respectively. The variation in soil respiration among different vegetation types could be well explained by SOC and soil total nitrogen content. Despite higher soil respiration in woodlands, SOC storage and residence time increased in the upper 20 cm of soil. Our results suggest that the differences in soil environmental conditions, especially soil substrate availability, influenced the level of annual soil respiration produced by different vegetation types. Moreover, shifts from grassland to woody plant dominance resulted in increased SOC storage. Given the widespread increase in woody plant abundance caused by climate change and large-scale afforestation programs, the soils are expected to accumulate and store increased amounts of organic carbon in temperate areas of China.

  7. Drivers of leaf carbon exchange capacity across biomes at the continental scale.

    Science.gov (United States)

    Smith, Nicholas G; Dukes, Jeffrey S

    2018-04-29

    Realistic representations of plant carbon exchange processes are necessary to reliably simulate biosphere-atmosphere feedbacks. These processes are known to vary over time and space, though the drivers of the underlying rates are still widely debated in the literature. Here, we measured leaf carbon exchange in >500 individuals of 98 species from the neotropics to high boreal biomes to determine the drivers of photosynthetic and dark respiration capacity. Covariate abiotic (long- and short-term climate) and biotic (plant type, plant size, ontogeny, water status) data were used to explore significant drivers of temperature-standardized leaf carbon exchange rates. Using model selection, we found the previous week's temperature and soil moisture at the time of measurement to be a better predictor of photosynthetic capacity than long-term climate, with the combination of high recent temperatures and low soil moisture tending to decrease photosynthetic capacity. Non-trees (annual and perennials) tended to have greater photosynthetic capacity than trees, and, within trees, adults tended to have greater photosynthetic capacity than juveniles, possibly as a result of differences in light availability. Dark respiration capacity was less responsive to the assessed drivers than photosynthetic capacity, with rates best predicted by multi-year average site temperature alone. Our results suggest that, across large spatial scales, photosynthetic capacity quickly adjusts to changing environmental conditions, namely light, temperature, and soil moisture. Respiratory capacity is more conservative and most responsive to longer-term conditions. Our results provide a framework for incorporating these processes into large-scale models and a dataset to benchmark such models. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  8. Leaf-IT: An Android application for measuring leaf area.

    Science.gov (United States)

    Schrader, Julian; Pillar, Giso; Kreft, Holger

    2017-11-01

    The use of plant functional traits has become increasingly popular in ecological studies because plant functional traits help to understand key ecological processes in plant species and communities. This also includes changes in diversity, inter- and intraspecific interactions, and relationships of species at different spatiotemporal scales. Leaf traits are among the most important traits as they describe key dimensions of a plant's life history strategy. Further, leaf area is a key parameter with relevance for other traits such as specific leaf area, which in turn correlates with leaf chemical composition, photosynthetic rate, leaf longevity, and carbon investment. Measuring leaf area usually involves the use of scanners and commercial software and can be difficult under field conditions. We present Leaf-IT, a new smartphone application for measuring leaf area and other trait-related areas. Leaf-IT is free, designed for scientific purposes, and runs on Android 4 or higher. We tested the precision and accuracy using objects with standardized area and compared the area measurements of real leaves with the well-established, commercial software WinFOLIA using the Altman-Bland method. Area measurements of standardized objects show that Leaf-IT measures area with high accuracy and precision. Area measurements with Leaf-IT of real leaves are comparable to those of WinFOLIA. Leaf-IT is an easy-to-use application running on a wide range of smartphones. That increases the portability and use of Leaf-IT and makes it possible to measure leaf area under field conditions typical for remote locations. Its high accuracy and precision are similar to WinFOLIA. Currently, its main limitation is margin detection of damaged leaves or complex leaf morphologies.

  9. Induction by ethylene of cyanide-resistant respiration

    Energy Technology Data Exchange (ETDEWEB)

    Solomos, T.; Laties, G.G.

    1976-05-17

    Ethylene and cyanide induce an increase in respiration in a variety of plant tissues, whereas ethylene has no effect on tissues whose respiration is strongly inhibited by cyanide. It is suggested that the existence of a cyanide-insensitive electron transport path is a prerequisite for stimulation of respiration by ethylene.

  10. A method for measuring losses of soil carbon by heterotrophic respiration from peat soils under oil palms

    Science.gov (United States)

    Farmer, Jenny; Manning, Frances; Smith, Jo; Arn Teh, Yit

    2017-04-01

    The effects of drainage and deforestation of South East Asian peat swamp forests for the development of oil palm plantations has received considerable attention in both mainstream media and academia, and is the source of significant discussion and debate. However, data on the long-term carbon losses from these peat soils as a result of this land use change is still limited and the methods with which to collect this data are still developing. Here we present the ongoing evolution and implementation of a method for separating autotrophic and heterotrophic respiration by sampling carbon dioxide emissions at increasing distance from palm trees. We present the limitations of the method, modelling approaches and results from our studies. In 2011 we trialled this method in Sumatra, Indonesia and collected rate measurements over a six day period in three ages of oil palm. In the four year oil palm site there were thirteen collars that had no roots present and from these the peat based carbon losses were recorded to be 0.44 g CO2 m2 hr-1 [0.34; 0.57] (equivalent to 39 t CO2 ha-1 yr-1 [30; 50]) with a mean water table depth of 0.40 m, or 63% of the measured total respiration across the plot. In the two older palm sites of six and seven years, only one collar out of 100 had no roots present, and thus a linear random effects model was developed to calculate heterotrophic emissions for different distances from the palm tree. This model suggested that heterotrophic respiration was between 37 - 59% of total respiration in the six year old plantation and 39 - 56% in the seven year old plantation. We applied this method in 2014 to a seven year old plantation, in Sarawak, Malaysia, modifying the method to include the heterotrophic contribution from beneath frond piles and weed covered areas. These results indicated peat based carbon losses to be 0.42 g CO2 m2 hr-1 [0.27;0.59] (equivalent to 37 t CO2 ha-1 yr-1 [24; 52]) at an average water table depth of 0.35 m, 47% of the measured

  11. Occupational Exposure to Respirable Dust, Respirable Crystalline Silica and Diesel Engine Exhaust Emissions in the London Tunnelling Environment.

    Science.gov (United States)

    Galea, Karen S; Mair, Craig; Alexander, Carla; de Vocht, Frank; van Tongeren, Martie

    2016-03-01

    Personal 8-h shift exposure to respirable dust, diesel engine exhaust emissions (DEEE) (as respirable elemental carbon), and respirable crystalline silica of workers involved in constructing an underground metro railway tunnel was assessed. Black carbon (BC) concentrations were also assessed using a MicroAeth AE51. During sprayed concrete lining (SCL) activities in the tunnel, the geometric mean (GM) respirable dust exposure level was 0.91mg m(-3), with the highest exposure measured on a back-up sprayer (3.20mg m(-3)). The GM respirable crystalline silica concentration for SCL workers was 0.03mg m(-3), with the highest measurement also for the back-up sprayer (0.24mg m(-3)). During tunnel boring machine (TBM) activities, the GM respirable dust concentration was 0.54mg m(-3). The GM respirable elemental carbon concentration for all the TBM operators was 18 µg m(-3); with the highest concentration measured on a segment lifter. The BC concentrations were higher in the SCL environment in comparison to the TBM environment (daily GM 18-54 µg m(-3) versus 3-6 µg m(-3)). This small-scale monitoring campaign provides additional personal data on exposures experienced by underground tunnel construction workers. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  12. Diel hysteresis between soil respiration and soil temperature in a biological soil crust covered desert ecosystem.

    Science.gov (United States)

    Guan, Chao; Li, Xinrong; Zhang, Peng; Chen, Yongle

    2018-01-01

    Soil respiration induced by biological soil crusts (BSCs) is an important process in the carbon (C) cycle in arid and semi-arid ecosystems, where vascular plants are restricted by the harsh environment, particularly the limited soil moisture. However, the interaction between temperature and soil respiration remains uncertain because of the number of factors that control soil respiration, including temperature and soil moisture, especially in BSC-dominated areas. In this study, the soil respiration in moss-dominated crusts and lichen-dominated crusts was continuously measured using an automated soil respiration system over a one-year period from November 2015 to October 2016 in the Shapotou region of the Tengger Desert, northern China. The results indicated that over daily cycles, the half-hourly soil respiration rates in both types of BSC-covered areas were commonly related to the soil temperature. The observed diel hysteresis between the half-hourly soil respiration rates and soil temperature in the BSC-covered areas was limited by nonlinearity loops with semielliptical shapes, and soil temperature often peaked later than the half-hourly soil respiration rates in the BSC-covered areas. The average lag times between the half-hourly soil respiration rates and soil temperature for both types of BSC-covered areas were two hours over the diel cycles, and they were negatively and linearly related to the volumetric soil water content. Our results highlight the diel hysteresis phenomenon that occurs between soil respiration rates and soil temperatures in BSC-covered areas and the negative response of this phenomenon to soil moisture, which may influence total C budget evaluations. Therefore, the interactive effects of soil temperature and moisture on soil respiration in BSC-covered areas should be considered in global carbon cycle models of desert ecosystems.

  13. Microbial properties explain temporal variation in soil respiration in a grassland subjected to nitrogen addition

    Science.gov (United States)

    Li, Yue; Liu, Yinghui; Wu, Shanmei; Niu, Lei; Tian, Yuqiang

    2015-01-01

    The role of soil microbial variables in shaping the temporal variability of soil respiration has been well acknowledged but is poorly understood, particularly under elevated nitrogen (N) deposition conditions. We measured soil respiration along with soil microbial properties during the early, middle, and late growing seasons in temperate grassland plots that had been treated with N additions of 0, 2, 4, 8, 16, or 32 g N m−2 yr−1 for 10 years. Representing the averages over three observation periods, total (Rs) and heterotrophic (Rh) respiration were highest with 4 g N m−2 yr−1, but autotrophic respiration (Ra) was highest with 8 to 16 g N m−2 yr−1. Also, the responses of Rh and Ra were unsynchronized considering the periods separately. N addition had no significant impact on the temperature sensitivity (Q10) for Rs but inhibited the Q10 for Rh. Significant interactions between observation period and N level occurred in soil respiration components, and the temporal variations in soil respiration components were mostly associated with changes in microbial biomass carbon (MBC) and phospholipid fatty acids (PLFAs). Further observation on soil organic carbon and root biomass is needed to reveal the long-term effect of N deposition on soil C sequestration. PMID:26678303

  14. Cassava brown streak disease effects on leaf metabolites and ...

    African Journals Online (AJOL)

    Cassava brown streak disease effects on leaf metabolites and pigment accumulation. ... Total reducing sugar and starch content also dropped significantly (-30 and -60%, respectively), much as NASE 14 maintained a relatively higher amount of carbohydrates. Leaf protein levels were significantly reduced at a rate of 0.07 ...

  15. Organic fertilizer application increases the soil respiration and net ecosystem carbon dioxide absorption of paddy fields under water-saving irrigation.

    Science.gov (United States)

    Yang, Shihong; Xiao, Ya Nan; Xu, Junzeng

    2018-04-01

    Quantifying carbon sequestration in paddy soil is necessary to understand the effect of agricultural practices on carbon cycles. The objective of this study was to assess the effect of organic fertilizer addition (MF) on the soil respiration and net ecosystem carbon dioxide (CO 2 ) absorption of paddy fields under water-saving irrigation (CI) in the Taihu Lake Region of China during the 2014 and 2015 rice-growing seasons. Compared with the traditional fertilizer and water management (FC), the joint regulation of CI and MF (CM) significantly increased the rice yields and irrigation water use efficiencies of paddy fields by 4.02~5.08 and 83.54~109.97% (p < 0.05). The effects of organic fertilizer addition on soil respiration and net ecosystem CO 2 absorption rates showed inter-annual differences. CM paddy fields showed a higher soil respiration and net CO 2 absorption rates during some periods of the rice growth stage in the first year and during most periods of the rice growth stage in the second year. These fields also had significantly higher total CO 2 emission through soil respiration (total R soil ) and total net CO 2 absorption compared with FC paddy fields (p < 0.05). The total R soil and net ecosystem CO 2 absorption of CM paddy fields were 67.39~91.55 and 129.41~113.75 mol m -2 , which were 27.66~135.52 and 12.96~31.66% higher than those of FC paddy fields. The interaction between water and fertilizer management had significant effects on total net ecosystem CO 2 absorption. The frequent alternate wet-dry cycles of CI paddy fields increased the soil respiration and reduced the net CO 2 absorption. Organic fertilizer promoted the soil respiration of paddy soil but also increased its net CO 2 absorption and organic carbon content. Therefore, the joint regulation of water-saving irrigation and organic fertilizer is an effective measure for maintaining yield, increasing irrigation water use efficiency, mitigating CO 2 emission, and promoting paddy

  16. Relations between soil respiration, humus quali­ty and ca­tion exchange capacity in selected subtypes of chernozem in South Moravia region

    Directory of Open Access Journals (Sweden)

    Jiřina Foukalová

    2008-01-01

    Full Text Available Soil organic matter (SOM undergoes short and long-term transformation in the soil. Microorganisms through their enzymes are able to mineralize organic carbon while the rate of this process is different. Biological test though referred to one of the main diagnostic methods for evaluating soil qualit­y/health. The aim of our work was to determine basal respiration, total carbon content, fractio­nal composition of humus and basic parameters of soil colloidal complex in selected subtypes of chernozem in South Moravia region. Basal respiration was measured using Vaisala GMT220 apparatus. Total carbon content was determined by oxidimetric titration and basic parameters of soil colloidal according to Mehlich. Results showed that production of carbon dioxide varied from 0.09 to 0.27 mg CO2/100g/h. Linear correlation between basal respiration and humification degree was found. Humus content varied from 2.15% to 4.6%. No correlation between quantity of humus and basal respiration was observed. Higher values of basal respiration were connected with higher quality of HS. Significant linear correlation between total carbon content (TOC and cation exchange capacity (CEC was found.

  17. The dosimetric impact of leaf interdigitation and leaf width on VMAT treatment planning in Pinnacle: comparing Pareto fronts

    International Nuclear Information System (INIS)

    Van Kesteren, Z; Janssen, T M; Damen, E; Van Vliet-Vroegindeweij, C

    2012-01-01

    To evaluate in an objective way the effect of leaf interdigitation and leaf width on volumetric modulated arc therapy plans in Pinnacle. Three multileaf collimators (MLCs) were modeled: two 10 mm leaf width MLCs, with and without interdigitating leafs, and a 5 mm leaf width MLC with interdigitating leafs. Three rectum patients and three prostate patients were used for the planning study. In order to compare treatment techniques in an objective way, a Pareto front comparison was carried out. 200 plans were generated in an automated way, per patient per MLC model, resulting in a total of 3600 plans. From these plans, Pareto-optimal plans were selected which were evaluated for various dosimetric variables. The capability of leaf interdigitation showed little dosimetric impact on the treatment plans, when comparing the 10 mm leaf width MLC with and without leaf interdigitation. When comparing the 10 mm leaf width MLC with the 5 mm leaf width MLC, both with interdigitating leafs, improvement in plan quality was observed. For both patient groups, the integral dose was reduced by 0.6 J for the thin MLC. For the prostate patients, the mean dose to the anal sphincter was reduced by 1.8 Gy and the conformity of the V 95% was reduced by 0.02 using the thin MLC. The V 65% of the rectum was reduced by 0.1% and the dose homogeneity with 1.5%. For rectum patients, the mean dose to the bowel was reduced by 1.4 Gy and the mean dose to the bladder with 0.8 Gy for the thin MLC. The conformity of the V 95% was equivalent for the 10 and 5 mm leaf width MLCs for the rectum patients. We have objectively compared three types of MLCs in a planning study for prostate and rectum patients by analyzing Pareto-optimal plans which were generated in an automated way. Interdigitation of MLC leafs does not generate better plans using the SmartArc algorithm in Pinnacle. Changing the MLC leaf width from 10 to 5 mm generates better treatment plans although the clinical relevance remains to be proven

  18. The dosimetric impact of leaf interdigitation and leaf width on VMAT treatment planning in Pinnacle: comparing Pareto fronts.

    Science.gov (United States)

    van Kesteren, Z; Janssen, T M; Damen, E; van Vliet-Vroegindeweij, C

    2012-05-21

    To evaluate in an objective way the effect of leaf interdigitation and leaf width on volumetric modulated arc therapy plans in Pinnacle. Three multileaf collimators (MLCs) were modeled: two 10 mm leaf width MLCs, with and without interdigitating leafs, and a 5 mm leaf width MLC with interdigitating leafs. Three rectum patients and three prostate patients were used for the planning study. In order to compare treatment techniques in an objective way, a Pareto front comparison was carried out. 200 plans were generated in an automated way, per patient per MLC model, resulting in a total of 3600 plans. From these plans, Pareto-optimal plans were selected which were evaluated for various dosimetric variables. The capability of leaf interdigitation showed little dosimetric impact on the treatment plans, when comparing the 10 mm leaf width MLC with and without leaf interdigitation. When comparing the 10 mm leaf width MLC with the 5 mm leaf width MLC, both with interdigitating leafs, improvement in plan quality was observed. For both patient groups, the integral dose was reduced by 0.6 J for the thin MLC. For the prostate patients, the mean dose to the anal sphincter was reduced by 1.8 Gy and the conformity of the V(95%) was reduced by 0.02 using the thin MLC. The V(65%) of the rectum was reduced by 0.1% and the dose homogeneity with 1.5%. For rectum patients, the mean dose to the bowel was reduced by 1.4 Gy and the mean dose to the bladder with 0.8 Gy for the thin MLC. The conformity of the V(95%) was equivalent for the 10 and 5 mm leaf width MLCs for the rectum patients. We have objectively compared three types of MLCs in a planning study for prostate and rectum patients by analyzing Pareto-optimal plans which were generated in an automated way. Interdigitation of MLC leafs does not generate better plans using the SmartArc algorithm in Pinnacle. Changing the MLC leaf width from 10 to 5 mm generates better treatment plans although the clinical relevance remains

  19. Inter-relationships between light and respiration in the control of ascorbic acid synthesis and accumulation in Arabidopsis thaliana leaves.

    Science.gov (United States)

    Bartoli, Carlos G; Yu, Jianping; Gómez, Facundo; Fernández, Laura; McIntosh, Lee; Foyer, Christine H

    2006-01-01

    The effects of growth irradiance and respiration on ascorbic acid (AA) synthesis and accumulation were studied in the leaves of wild-type and transformed Arabidopsis thaliana with modified amounts of the mitochondrial alternative oxidase (AOX) protein. Plants were grown under low (LL; 50 micromol photons m(-2) s(-1)), intermediate (IL; 100 micromol photons m(-2) s(-1)), or high (HL; 250 micromol photons m(-2) s(-1)) light. Increasing growth irradiance progressively elevated leaf AA content and hence the values of dark-induced disappearance of leaf AA, which were 11, 55, and 89 nmol AA lost g(-1) fresh weight h(-1), from LL-, IL-, and HL-grown leaves, respectively. When HL leaves were supplied with L-galactone-1,4-lactone (L-GalL; the precursor of AA), they accumulated twice as much AA and had double the maximal L-galactone-1,4-lactone dehydrogenase (L-GalLDH) activities of LL leaves. Growth under HL enhanced dehydroascorbate reductase and monodehydroascorbate reductase activities. Leaf respiration rates were highest in the HL leaves, which also had higher amounts of cytochrome c and cytochrome c oxidase (CCO) activities, as well as enhanced capacity of the AOX and CCO electron transport pathways. Leaves of the AOX-overexpressing lines accumulated more AA than wild-type or antisense leaves, particularly at HL. Intact mitochondria from AOX-overexpressing lines had higher AA synthesis capacities than those from the wild-type or antisense lines even though they had similar L-GalLDH activities. AOX antisense lines had more cytochrome c protein than wild-type or AOX-overexpressing lines. It is concluded that regardless of limitations on L-GalL synthesis by regulation of early steps in the AA synthesis pathway, the regulation of L-GalLDH activity via the interaction of light and respiratory controls is a crucial determinant of the overall ability of leaves to produce and accumulate AA.

  20. Frost Induces Respiration and Accelerates Carbon Depletion in Trees.

    Science.gov (United States)

    Sperling, Or; Earles, J Mason; Secchi, Francesca; Godfrey, Jessie; Zwieniecki, Maciej A

    2015-01-01

    Cellular respiration depletes stored carbohydrates during extended periods of limited photosynthesis, e.g. winter dormancy or drought. As respiration rate is largely a function of temperature, the thermal conditions during such periods may affect non-structural carbohydrate (NSC) availability and, ultimately, recovery. Here, we surveyed stem responses to temperature changes in 15 woody species. For two species with divergent respirational response to frost, P. integerrima and P. trichocarpa, we also examined corresponding changes in NSC levels. Finally, we simulated respiration-induced NSC depletion using historical temperature data for the western US. We report a novel finding that tree stems significantly increase respiration in response to near freezing temperatures. We observed this excess respiration in 13 of 15 species, deviating 10% to 170% over values predicted by the Arrhenius equation. Excess respiration persisted at temperatures above 0 °C during warming and reoccurred over multiple frost-warming cycles. A large adjustment of NSCs accompanied excess respiration in P. integerrima, whereas P. trichocarpa neither excessively respired nor adjusted NSCs. Over the course of the years included in our model, frost-induced respiration accelerated stem NSC consumption by 8.4 mg (glucose eq.) cm(-3) yr(-1) on average in the western US, a level of depletion that may continue to significantly affect spring NSC availability. This novel finding revises the current paradigm of low temperature respiration kinetics.

  1. Frost Induces Respiration and Accelerates Carbon Depletion in Trees.

    Directory of Open Access Journals (Sweden)

    Or Sperling

    Full Text Available Cellular respiration depletes stored carbohydrates during extended periods of limited photosynthesis, e.g. winter dormancy or drought. As respiration rate is largely a function of temperature, the thermal conditions during such periods may affect non-structural carbohydrate (NSC availability and, ultimately, recovery. Here, we surveyed stem responses to temperature changes in 15 woody species. For two species with divergent respirational response to frost, P. integerrima and P. trichocarpa, we also examined corresponding changes in NSC levels. Finally, we simulated respiration-induced NSC depletion using historical temperature data for the western US. We report a novel finding that tree stems significantly increase respiration in response to near freezing temperatures. We observed this excess respiration in 13 of 15 species, deviating 10% to 170% over values predicted by the Arrhenius equation. Excess respiration persisted at temperatures above 0 °C during warming and reoccurred over multiple frost-warming cycles. A large adjustment of NSCs accompanied excess respiration in P. integerrima, whereas P. trichocarpa neither excessively respired nor adjusted NSCs. Over the course of the years included in our model, frost-induced respiration accelerated stem NSC consumption by 8.4 mg (glucose eq. cm(-3 yr(-1 on average in the western US, a level of depletion that may continue to significantly affect spring NSC availability. This novel finding revises the current paradigm of low temperature respiration kinetics.

  2. Partitioning of Respiration in an Animal-Algal Symbiosis: Implications for Different Aerobic Capacity Between Symbiodinium spp.

    Directory of Open Access Journals (Sweden)

    Thomas David Hawkins

    2016-04-01

    Full Text Available Cnidarian-dinoflagellate symbioses are ecologically important and the subject of much investigation. However, our understanding of critical aspects of symbiosis physiology, such as the partitioning of total respiration between the host and symbiont, remains incomplete. Specifically, we know little about how the relationship between host and symbiont respiration varies between different holobionts (host-symbiont combinations. We applied molecular and biochemical techniques to investigate aerobic respiratory capacity in naturally symbiotic Exaiptasia pallida sea anemones, alongside animals infected with either homologous ITS2-type A4 Symbiodinium or a heterologous isolate of Symbiodinium minutum (ITS2-type B1. In naturally symbiotic anemones, host, symbiont, and total holobiont mitochondrial citrate synthase (CS enzyme activity, but not host mitochondrial copy number, were reliable predictors of holobiont respiration. There was a positive association between symbiont density and host CS specific activity (mg protein-1, and a negative correlation between host- and symbiont CS specific activities. Notably, partitioning of total CS activity between host and symbiont in this natural E. pallida population was significantly different to the host/symbiont biomass ratio. In re-infected anemones, we found significant between-holobiont differences in the CS specific activity of the algal symbionts. Furthermore, the relationship between the partitioning of total CS activity and the host/symbiont biomass ratio differed between holobionts. These data have broad implications for our understanding of cnidarian-algal symbiosis. Specifically, the long-held assumption of equivalency between symbiont/host biomass and respiration ratios can result in significant overestimation of symbiont respiration and potentially erroneous conclusions regarding the percentage of carbon translocated to the host. The interspecific variability in symbiont aerobic capacity provides

  3. Characterization, antibacterial, total antioxidant, scavenging, reducing power and ion chelating activities of green synthesized silver, copper and titanium dioxide nanoparticles using Artemisia haussknechtii leaf extract.

    Science.gov (United States)

    Alavi, Mehran; Karimi, Naser

    2017-12-12

    Recently, major problem related to pathogenic bacteria is augmentation of antibiotic resistance which has been changed treatment and recovery of millions of infectious patients. The present study reports an eco-friendly, rapid and easy method for synthesis of silver (Ag), copper (Cu) and titanium dioxide (TiO 2 ) nanoparticles (NPs) using Artemisia haussknechtii leaf aqueous extract with antibacterial activities against multi-drug resistance (MDR) bacteria species. Three different concentrations (0.001, 0.01 and 0.1 M) of AgNO 3 , CuSO 4 and TiO (OH) 2 were investigated for obtaining optimum NPs green synthesis. Total phenolic content, total flavonoid content of leaf extract and total antioxidant activity (DPPH) assay were determined as radical scavenging methods. UV-Visible spectroscopy, Fourier transform infrared spectroscopy analysis, X-ray diffraction, energy dispersive X-ray spectroscopy, field emission scanning electron microscope and atomic force microscopy (AFM) were used due to NPs characterization. The size average of the Ag, Cu and TiO 2 NPs obtained were respectively 10.69 ± 5.55, 35.36 ± 44.4 and 92.58 ± 56.98 nm. In the case of antibacterial assay, disc diffusion assay, minimum inhibitory concentration, minimum bactericidal concentration, bacterial growth and morphology of four MDR species Staphylococcus aureus ATCC 43300, Staphylococcus epidermidis ATCC 12258, Serratia marcescens ATTC13880 and Escherichia coli ATCC 25922 were evaluated. Results of this study demonstrated that A. haussknechtii leaf extract with various groups of phytochemicals such as phenols and flavonoids had suitable ability in green synthesis of Ag, Cu and TiO 2 NPs. Also, Ag and Cu NPs had more antibacterial activities compared to TiO 2 NPs.

  4. Transcriptional analyses of natural leaf senescence in maize.

    Directory of Open Access Journals (Sweden)

    Wei Yang Zhang

    Full Text Available Leaf senescence is an important biological process that contributes to grain yield in crops. To study the molecular mechanisms underlying natural leaf senescence, we harvested three different developmental ear leaves of maize, mature leaves (ML, early senescent leaves (ESL, and later senescent leaves (LSL, and analyzed transcriptional changes using RNA-sequencing. Three sets of data, ESL vs. ML, LSL vs. ML, and LSL vs. ESL, were compared, respectively. In total, 4,552 genes were identified as differentially expressed. Functional classification placed these genes into 18 categories including protein metabolism, transporters, and signal transduction. At the early stage of leaf senescence, genes involved in aromatic amino acids (AAAs biosynthetic process and transport, cellular polysaccharide biosynthetic process, and the cell wall macromolecule catabolic process, were up-regulated. Whereas, genes involved in amino acid metabolism, transport, apoptosis, and response to stimulus were up-regulated at the late stage of leaf senescence. Further analyses reveals that the transport-related genes at the early stage of leaf senescence potentially take part in enzyme and amino acid transport and the genes upregulated at the late stage are involved in sugar transport, indicating nutrient recycling mainly takes place at the late stage of leaf senescence. Comparison between the data of natural leaf senescence in this study and previously reported data for Arabidopsis implies that the mechanisms of leaf senescence in maize are basically similar to those in Arabidopsis. A comparison of natural and induced leaf senescence in maize was performed. Athough many basic biological processes involved in senescence occur in both types of leaf senescence, 78.07% of differentially expressed genes in natural leaf senescence were not identifiable in induced leaf senescence, suggesting that differences in gene regulatory network may exist between these two leaf senescence

  5. Forest Ecosystem respiration estimated from eddy covariance and chamber measurements under high turbulence and substantial tree mortality from bark beetles

    Science.gov (United States)

    Speckman, Heather N.; Frank, John M.; Bradford, John B.; Miles, Brianna L.; Massman, William J.; Parton, William J.; Ryan, Michael G.

    2015-01-01

    Eddy covariance nighttime fluxes are uncertain due to potential measurement biases. Many studies report eddy covariance nighttime flux lower than flux from extrapolated chamber measurements, despite corrections for low turbulence. We compared eddy covariance and chamber estimates of ecosystem respiration at the GLEES Ameriflux site over seven growing seasons under high turbulence (summer night mean friction velocity (u*) = 0.7 m s−1), during which bark beetles killed or infested 85% of the aboveground respiring biomass. Chamber-based estimates of ecosystem respiration during the growth season, developed from foliage, wood and soil CO2 efflux measurements, declined 35% after 85% of the forest basal area had been killed or impaired by bark beetles (from 7.1 ±0.22 μmol m−2 s−1 in 2005 to 4.6 ±0.16 μmol m−2 s−1 in 2011). Soil efflux remained at ~3.3 μmol m−2 s−1 throughout the mortality, while the loss of live wood and foliage and their respiration drove the decline of the chamber estimate. Eddy covariance estimates of fluxes at night remained constant over the same period, ~3.0 μmol m−2 s−1 for both 2005 (intact forest) and 2011 (85% basal area killed or impaired). Eddy covariance fluxes were lower than chamber estimates of ecosystem respiration (60% lower in 2005, and 32% in 2011), but the mean night estimates from the two techniques were correlated within a year (r2 from 0.18-0.60). The difference between the two techniques was not the result of inadequate turbulence, because the results were robust to a u* filter of > 0.7 m s−1. The decline in the average seasonal difference between the two techniques was strongly correlated with overstory leaf area (r2=0.92). The discrepancy between methods of respiration estimation should be resolved to have confidence in ecosystem carbon flux estimates.

  6. Forest ecosystem respiration estimated from eddy covariance and chamber measurements under high turbulence and substantial tree mortality from bark beetles.

    Science.gov (United States)

    Speckman, Heather N; Frank, John M; Bradford, John B; Miles, Brianna L; Massman, William J; Parton, William J; Ryan, Michael G

    2015-02-01

    Eddy covariance nighttime fluxes are uncertain due to potential measurement biases. Many studies report eddy covariance nighttime flux lower than flux from extrapolated chamber measurements, despite corrections for low turbulence. We compared eddy covariance and chamber estimates of ecosystem respiration at the GLEES Ameriflux site over seven growing seasons under high turbulence [summer night mean friction velocity (u*) = 0.7 m s(-1)], during which bark beetles killed or infested 85% of the aboveground respiring biomass. Chamber-based estimates of ecosystem respiration during the growth season, developed from foliage, wood, and soil CO2 efflux measurements, declined 35% after 85% of the forest basal area had been killed or impaired by bark beetles (from 7.1 ± 0.22 μmol m(-2) s(-1) in 2005 to 4.6 ± 0.16 μmol m(-2) s(-1) in 2011). Soil efflux remained at ~3.3 μmol m(-2) s(-1) throughout the mortality, while the loss of live wood and foliage and their respiration drove the decline of the chamber estimate. Eddy covariance estimates of fluxes at night remained constant over the same period, ~3.0 μmol m(-2) s(-1) for both 2005 (intact forest) and 2011 (85% basal area killed or impaired). Eddy covariance fluxes were lower than chamber estimates of ecosystem respiration (60% lower in 2005, and 32% in 2011), but the mean night estimates from the two techniques were correlated within a year (r(2) from 0.18 to 0.60). The difference between the two techniques was not the result of inadequate turbulence, because the results were robust to a u* filter of >0.7 m s(-1). The decline in the average seasonal difference between the two techniques was strongly correlated with overstory leaf area (r(2) = 0.92). The discrepancy between methods of respiration estimation should be resolved to have confidence in ecosystem carbon flux estimates. © 2014 John Wiley & Sons Ltd.

  7. A Standard Characterization Methodology for Respirable Coal Mine Dust Using SEM-EDX

    Directory of Open Access Journals (Sweden)

    Rachel Sellaro

    2015-12-01

    Full Text Available A key consideration for responsible development of mineral and energy resources is the well-being of workers. Respirable dust in mining environments represents a serious concern for occupational health. In particular, coal miners can be exposed to a variety of dust characteristics depending on their work activities, and some exposures may pose risk for lung diseases like CWP and silicosis. As underscored by common regulatory frameworks, respirable dust exposures are generally characterized on the basis of total mass concentration, and also the silica mass fraction. However, relatively little emphasis has been placed on other dust characteristics that may be important in terms of identifying health risks. Comprehensive particle-level analysis to estimate chemistry, size, and shape distributions of particles is possible. This paper describes a standard methodology for characterization of respirable coal mine dust using scanning electron microscopy (SEM with energy dispersive X-ray (EDX. Preliminary verification of the method is shown based several dust samples collected from an underground mine in Central Appalachia.

  8. Independent Evaluation of The Lepestok Filtering Facepiece Respirator

    International Nuclear Information System (INIS)

    Hoover, Mark D; Vargo, George J

    2001-01-01

    The purpose of this study was to determine the protection factor of the Lepestok-200 filtering facepiece respirator by conducting a standard quantitative fit test on a panel of 25 representative adults (14 males and 11 females) using the TSI Incorporated PortaCount PlusTM quantitative fit-testing system. Each subject was tested four times. In the total of 100 tests, 95% of the overall fit factors were greater than 3, more than 80% of the overall fit factors were greater than 14, approximately 50% were greater than 86, and 20% were greater than 200. The pass-fail performance of the respirator was similar for each of the six exercises in the test series: (1) normal breathing, (2) deep breathing, (3) moving the head side to side, (4) moving the head up and down, (5) reading a passage of text out loud, and (6) normal breathing, indicating that the respirator performs equally well for each type of exercise. A significant and sustained improvement in fit factor was observed after the initial test, indicating that the subjects benefited from the knowledge gained in the first of the four quantitative fit tests. In the 75 tests conducted after the initial test for each individual, 95% of the overall fit factors were greater than 6, more than 80% of the overall fit factors were greater than 23, and 50% were greater than 116, and 20% were greater than 200. Thus, the initial learning experienced doubled the fit factor for subsequent tests. In addition, there is an indication that the Lepestok-200 may perform better on wearers with wider faces than on individuals with narrower faces. The results of this study demonstrate the effectiveness of the Lepestok-200 respirator and reinforce the general conclusion that quantitative fit-testing can make an important contribution to ensuring that proper protection factors are achieved for workers

  9. Respiration and Heartbeat Measurement for Sleep Monitoring Using a Flexible AlN Piezoelectric Film Sensor

    Directory of Open Access Journals (Sweden)

    Nan BU

    2009-11-01

    Full Text Available Respiratory and heartbeat monitoring during sleep provides basic physiological information for diagnosis of sleep disorders. This paper proposes a new method for non-invasive and unconstrained measurement of respiration and heartbeat during sleep. A flexible piezoelectric film sensor made of aluminum nitride (AlN material is used for signal acquisition. The total thickness of this sensor is less than 40 μm; the thin thickness makes it imperceptible when integrated into a bed. In addition, the AlN film sensor has good sensitivity, so that pressure fluctuation due to respiration and heartbeat can be measured when a subject is lying on this sensor. The pressure fluctuation measured can be further separated into signals corresponding to respiration and heartbeat, respectively. In the proposed method, the signal separation is achieved using an algorithm based on empirical mode decomposition (EMD. From the experimental results, it was found that respiration and heartbeat signals can be successfully obtained with the proposed method.

  10. Experimental study on effects of drilling parameters on respirable dust production during roof bolting operations.

    Science.gov (United States)

    Jiang, Hua; Luo, Yi; McQuerrey, Joe

    2018-02-01

    Underground coalmine roof bolting operators exhibit a continued risk for overexposure to airborne levels of respirable coal and crystalline silica dust from the roof drilling operation. Inhaling these dusts can cause coal worker's pneumoconiosis and silicosis. This research explores the effect of drilling control parameters, specifically drilling bite depth, on the reduction of respirable dust generated during the drilling process. Laboratory drilling experiments were conducted and results demonstrated the feasibility of this dust control approach. Both the weight and size distribution of the dust particles collected from drilling tests with different bite depths were analyzed. The results showed that the amount of total inhalable and respirable dust was inversely proportional to the drilling bite depth. Therefore, control of the drilling process to achieve proper high-bite depth for the rock can be an important approach to reducing the generation of harmful dust. Different from conventional passive engineering controls, such as mist drilling and ventilation approaches, this approach is proactive and can cut down the generation of respirable dust from the source. These findings can be used to develop an integrated drilling control algorithm to achieve the best drilling efficiency as well as reducing respirable dust and noise.

  11. Estimate of respiration rate and physicochemical changes of fresh-cut apples stored under different temperatures

    Directory of Open Access Journals (Sweden)

    Cristiane Fagundes

    2013-03-01

    Full Text Available In this study, the influence of storage temperature and passive modified packaging (PMP on the respiration rate and physicochemical properties of fresh-cut Gala apples (Malus domestica B. was investigated. The samples were packed in flexible multilayer bags and stored at 2 °C, 5 °C, and 7 °C for eleven days. Respiration rate as a function of CO2 and O2 concentrations was determined using gas chromatography. The inhibition parameters were estimated using a mathematical model based on Michaelis-Menten equation. The following physicochemical properties were evaluated: total soluble solids, pH, titratable acidity, and reducing sugars. At 2 °C, the maximum respiration rate was observed after 150 hours. At 5 °C and 7 °C the maximum respiration rates were observed after 100 and 50 hours of storage, respectively. The inhibition model results obtained showed a clear effect of CO2 on O2 consumption. The soluble solids decreased, although not significantly, during storage at the three temperatures studied. Reducing sugars and titratable acidity decreased during storage and the pH increased. These results indicate that the respiration rate influenced the physicochemical properties.

  12. A finger leaf design for dual layer MLCs

    International Nuclear Information System (INIS)

    Cui Weijie; Dai Jianrong

    2010-01-01

    Objective: To introduce a finger leaf design that is applied to dual layer MLCs. Methods: An optimization model was firstly constructed to describe the problem of determining leaf end shapes,and the corresponding problems were then solved by the simplex search method or the simulated annealing technique. Optimal parameters for arc shapes of leaf end projections were obtained, and a comparison was done between optimized MLCs and conventional MLCs in terms of field conformity. The optimization process was based on 634 target fields selected from the patient data base of a treatment planning system. Areas of these fields ranged from 20.0 to 602.7 cm with a mean and its standard deviation of (125.7 ± 0.0) cm 2 . Results: The optimized leaf end shapes projected to the isocenter plane were semicircles. With the finger leaf design, the total area of discrepancy regions between MLC fields and target fields was reduced by 32.3%. Conclusions: The finger leaf design improves the conformity of the MLC shaped fields to the desired target fields. (authors)

  13. Impact of Environmental Factors and Biological Soil Crust Types on Soil Respiration in a Desert Ecosystem

    Science.gov (United States)

    Feng, Wei; Zhang, Yuqing; Jia, Xin; Wu, Bin; Zha, Tianshan; Qin, Shugao; Wang, Ben; Shao, Chenxi; Liu, Jiabin; Fa, Keyu

    2014-01-01

    The responses of soil respiration to environmental conditions have been studied extensively in various ecosystems. However, little is known about the impacts of temperature and moisture on soils respiration under biological soil crusts. In this study, CO2 efflux from biologically-crusted soils was measured continuously with an automated chamber system in Ningxia, northwest China, from June to October 2012. The highest soil respiration was observed in lichen-crusted soil (0.93±0.43 µmol m−2 s−1) and the lowest values in algae-crusted soil (0.73±0.31 µmol m−2 s−1). Over the diurnal scale, soil respiration was highest in the morning whereas soil temperature was highest in the midday, which resulted in diurnal hysteresis between the two variables. In addition, the lag time between soil respiration and soil temperature was negatively correlated with the soil volumetric water content and was reduced as soil water content increased. Over the seasonal scale, daily mean nighttime soil respiration was positively correlated with soil temperature when moisture exceeded 0.075 and 0.085 m3 m−3 in lichen- and moss-crusted soil, respectively. However, moisture did not affect on soil respiration in algae-crusted soil during the study period. Daily mean nighttime soil respiration normalized by soil temperature increased with water content in lichen- and moss-crusted soil. Our results indicated that different types of biological soil crusts could affect response of soil respiration to environmental factors. There is a need to consider the spatial distribution of different types of biological soil crusts and their relative contributions to the total C budgets at the ecosystem or landscape level. PMID:25050837

  14. Impact of environmental factors and biological soil crust types on soil respiration in a desert ecosystem.

    Science.gov (United States)

    Feng, Wei; Zhang, Yuqing; Jia, Xin; Wu, Bin; Zha, Tianshan; Qin, Shugao; Wang, Ben; Shao, Chenxi; Liu, Jiabin; Fa, Keyu

    2014-01-01

    The responses of soil respiration to environmental conditions have been studied extensively in various ecosystems. However, little is known about the impacts of temperature and moisture on soils respiration under biological soil crusts. In this study, CO2 efflux from biologically-crusted soils was measured continuously with an automated chamber system in Ningxia, northwest China, from June to October 2012. The highest soil respiration was observed in lichen-crusted soil (0.93 ± 0.43 µmol m-2 s-1) and the lowest values in algae-crusted soil (0.73 ± 0.31 µmol m-2 s-1). Over the diurnal scale, soil respiration was highest in the morning whereas soil temperature was highest in the midday, which resulted in diurnal hysteresis between the two variables. In addition, the lag time between soil respiration and soil temperature was negatively correlated with the soil volumetric water content and was reduced as soil water content increased. Over the seasonal scale, daily mean nighttime soil respiration was positively correlated with soil temperature when moisture exceeded 0.075 and 0.085 m3 m-3 in lichen- and moss-crusted soil, respectively. However, moisture did not affect on soil respiration in algae-crusted soil during the study period. Daily mean nighttime soil respiration normalized by soil temperature increased with water content in lichen- and moss-crusted soil. Our results indicated that different types of biological soil crusts could affect response of soil respiration to environmental factors. There is a need to consider the spatial distribution of different types of biological soil crusts and their relative contributions to the total C budgets at the ecosystem or landscape level.

  15. Effects of rhizobacteria on the respiration and growth of Cerasus sachalinensis Kom. seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Qin, S.; Zhou, W.; Li, Z.; Lyu, D.

    2016-11-01

    In this study, we investigated the influence of rhizosphere microorganisms on seed germination and root metabolism in Cerasus sachalinensis Kom. We inoculated C. sachalinensis plants with suspensions of dominant bacterial strains isolated from their rhizosphere. Four bacterial strains each with significant growth-promoting or growth-inhibiting effects were screened from the efficient root-colonizing microorganisms. The number of actinomycetes increased and that of fungi decreased significantly in the seedling rhizospheres after rhizobacteria treatment. The growth-promoting bacteria slightly affected the respiration rates and respiratory pathway enzymes, but significantly improved root viability, root carbohydrate concentration and seedling growth. Bacillus cereus, Staphylococcus sp. and Pseudomonas fluorescens were identified as the growth-promoting rhizobacteria; one strain could not be identified. After inoculation with the growth-inhibiting bacteria, the number of fungal colonies in the seedling rhizospheres increased and root viability and respiration rate as well as starch and sucrose accumulation in the roots significantly decreased. The glycolysis, pentose phosphate and alternative oxidase pathways became the major pathways of respiratory metabolism after inoculation with the growth-inhibiting bacteria. The height, leaf number, growth and dry weight of the seedlings decreased significantly in plants inoculated with the growth-inhibiting bacteria. Inoculation of C. sachalinensis rhizosphere with growth-promoting and growth-inhibiting bacteria affected the soil environmental factors such as microbial group composition, nutrient concentration and seedling biomass. (Author)

  16. The Arabidopsis thaliana natriuretic peptide AtPNP-A is a systemic regulator of leaf dark respiration and signals via the phloem

    KAUST Repository

    Ruzvidzo, Oziniel; Donaldson, Lara Elizabeth; Valentine, Alex J.; Gehring, Christoph A

    2011-01-01

    -molar concentrations. Here we show that a recombinant Arabidopsis thaliana PNP (AtPNP-A) rapidly increased the rate of dark respiration in treated leaves after 5 min. In addition, we observed increases in lower leaves, and with a lag time of 10 min, the effect spread

  17. Global net primary production and heterotrophic respiration for 1987

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, R.E. Jr.; Piper, S.C.; Nemani, R. [Univ. of Montana, Missoula, MT (United States)]|[Scripps Institute of Oceanography, La Jolla, CA (United States)] [and others

    1995-06-01

    An ecosystem process model, BIOME-BGC, was parameterized and used to simulate the actual net primary production and heterotrophic respiration using daily climatic data, land cover type, leaf area index gridded to 1{degree} latitude by 1{degree} longitude grid cells for the year 1987. Global net primary production was 52 Pg C. These estimates were validated directly by two different methods. First, the grid cells were aggregated and used as inputs to a 3D atmospheric transport model, to compare CO{sub 2} station data with predictions. We simulated the intra-annual variation of atmospheric CO{sub 2} well for the northern hemisphere, but not for the southern hemisphere. Second, we calculated the net {sup 13}C uptake of vegetation, which is a function of water use efficiency. The {sup 13}C/{sup 12}C ratios agreed with measured data, indicating a strong limitation of global primary processes by the hydrologic cycle, especially precipitation. These are different from other global carbon models as we can simulate the year-to-year variation of climate, including El Nino, on the global carbon cycle.

  18. BOREAS TE-5 Soil Respiration Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. Soil respiration data were collected from 26-May-94 to 07-Sep-94 in the BOREAS NSA and SSA to compare the soil respiration rates in different forest sites using a LI-COR 6200 soil respiration chamber (model 6299). The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distrobuted Activity Archive Center (DAAC).

  19. Seasonal patterns of leaf gas exchange and water relations in dry rain forest trees of contrasting leaf phenology.

    Science.gov (United States)

    Choat, Brendan; Ball, Marilyn C; Luly, Jon G; Donnelly, Christine F; Holtum, Joseph A M

    2006-05-01

    Diurnal and seasonal patterns of leaf gas exchange and water relations were examined in tree species of contrasting leaf phenology growing in a seasonally dry tropical rain forest in north-eastern Australia. Two drought-deciduous species, Brachychiton australis (Schott and Endl.) A. Terracc. and Cochlospermum gillivraei Benth., and two evergreen species, Alphitonia excelsa (Fenzal) Benth. and Austromyrtus bidwillii (Benth.) Burret. were studied. The deciduous species had higher specific leaf areas and maximum photosynthetic rates per leaf dry mass in the wet season than the evergreens. During the transition from wet season to dry season, total canopy area was reduced by 70-90% in the deciduous species and stomatal conductance (g(s)) and assimilation rate (A) were markedly lower in the remaining leaves. Deciduous species maintained daytime leaf water potentials (Psi(L)) at close to or above wet season values by a combination of stomatal regulation and reduction in leaf area. Thus, the timing of leaf drop in deciduous species was not associated with large negative values of daytime Psi(L) (greater than -1.6 MPa) or predawn Psi(L) (greater than -1.0 MPa). The deciduous species appeared sensitive to small perturbations in soil and leaf water status that signalled the onset of drought. The evergreen species were less sensitive to the onset of drought and g(s) values were not significantly lower during the transitional period. In the dry season, the evergreen species maintained their canopies despite increasing water-stress; however, unlike Eucalyptus species from northern Australian savannas, A and g(s) were significantly lower than wet season values.

  20. Acceptable respiratory protection program and LASL respirator research

    International Nuclear Information System (INIS)

    Skaggs, B.J.

    1979-01-01

    A short history is presented on the LASL Respiratory Protection Training Programs. Then a discussion is given on the major points of an acceptable respiratory protection program utilizing the points required by the Occupational, Safety, and Health Administration (OSHA) Regulation 29 CFR 1910.134. Contributions to respirator research are reviewed. Discussion is presented under the following section headings: program administration; respirator selection; respirator use; fitting and training; respirator maintenance; medical clearance and surveillance; special problems; program evaluation; and documentation

  1. Soil respiration dynamics in the middle taiga of Central Siberia region

    Science.gov (United States)

    Makhnykina, Anastasia; Prokushkin, Anatoly; Polosukhina, Daria

    2017-04-01

    A large amount of carbon in soil is released to the atmosphere through soil respiration, which is the main pathway of transferring carbon from terrestrial ecosystems (Comstedt et al., 2011). Considering that boreal forests is a large terrestrial sink (Tans et al., 1990) and represent approximately 11 % of the Earth's total land area (Gower et al., 2001), even a small change in soil respiration could significantly intensify - or mitigate - current atmospheric increases of CO2, with potential feedbacks to climate change. The objectives of the present study are: (a) to study the dynamic of CO2 emission from the soil surface during summer season (from May to October); (b) to identify the reaction of soil respiration to different amount of precipitation as the main limiting factor in the region. The research was located in the pine forests in Central Siberia (60°N, 90°E), Russia. Sample plots were represented by the lichen pine forest, moss pine forest, mixed forest and anthropogenic destroyed area. We used the automated soil CO2 flux system based on the infrared gas analyzer -LI-8100 for measuring the soil efflux. Soil temperature was measured with Soil Temperature Probe Type E in three depths -5, 10, 15 cm. Volumetric soil moisture was measured with Theta Probe Model ML2. The presence and type of ground cover substantially affects the value of soil respiration fluxes. The carbon dioxide emission from the soil surface averaged 5.4 ±2.3 μmol CO2 m-2 s-1. The destroyed area without plant cover demonstrated the lowest soil respiration (0.1-5.6 μmol CO2 m-2 s-1). The lowest soil respiration among forested areas was observed in the feathermoss pine forest. The lichen pine forest was characterized by the intermediate values of soil respiration. The maximum soil respiration values and seasonal fluctuations were obtained in the mixed forest (2.3-29.3 μmol CO2 m-2 s-1). The analysis of relation between soil CO2 efflux and climatic conditions identified the parameters with

  2. [Research progress on photosynthesis regulating and controlling soil respiration].

    Science.gov (United States)

    Jing, Yan-Li; Guan, De-Xin; Wu, Jia-Bing; Wang, An-Zhi; Yuan, Feng-Hui

    2013-01-01

    To understand the mechanisms of soil respiration and accurately estimate its magnitude are the crucial basis of evaluating global carbon balance. However, the previously built soil respiration forecast models usually neglect the physiological processes that photosynthesis supplies substrates for rhizospheric respiration, leading to the defect in evaluating the mechanisms of soil respiration. This paper summarized the research progress on the mechanisms of photosynthetic regulation and control of soil respiration, introduced the related main research methods, and discussed the existing problems and research hotspots.

  3. What controls respiration rate in stored sugarbeet roots

    Science.gov (United States)

    Although respiration is estimated to be responsible for 60 to 80% of the sucrose lost during storage, the mechanisms by which sugarbeet roots regulate their respiration rate are unknown. In plants, respiration rate is regulated by (1) available respiratory capacity, (2) cellular energy status, (3) ...

  4. Total flavonoid and phenolic contents of n-butanol extract of Samanea saman leaf and the antibacterial activity towards Escherichia coli and Staphylococcus aureus

    Science.gov (United States)

    Rita, Wiwik Susanah; Swantara, I. Made Dira; Asih, I. A. Raka Astiti; Sinarsih, Ni Ketut; Suteja, I. Kadek Pater

    2016-03-01

    Total flavonoid and phenolic contents in some natural products was suspected of having a positive correlation to its activity in inhibiting the growth of bacteria. The aim of this study was to determine the total flavonoid and phenolic contents of n-butanol extract of Samanea saman leaf, and to evaluate the antibacterial activity towards Escherechia coli and Staphylococcus aureus. Extraction of compounds was done by ethanol 96%, followed by fractionation into n-hexane, ethyl acetate, and n-butanol. Determination of total flavonoid and phenolic contents was done by UV-Vis Spectrophotometer using standard of quersetin and galic acid respectively. In addition, antibacterial activity was evaluated by agar disc diffusion method. Extraction of 1000 g of Samanea saman leaf was obtained 80 g of ethanol extracts, fractionation of the extract was obtained 8.02 g of n-hexane extracts, 7.11 g of ethyl acetate extracts, 13.5 g of n-butanol extracts, and 14.16 g of aqueous extracts. Phytochemical screening of the n-butanol extracts revealed the presence of flavonoid and phenolic compounds. Total flavonoid and phenolic contents were successively 43.5798 mg QE/100g and 34.0180 mg GAE/100g. The butanol extracts inhibited the growth of S.aureus higher than the growth of E.coli. At the concentration of 2, 4, 6, 8 % (b/v), and positive control (meropenem μg/disc), inhibition zone towards S. aureus was successively 5.67, 9.33, 10.33, 12.00, and 32.33 mm, while the inhibition zone towards E. coli was1.33, 3.33, 4.33, 5.43, and 34.00 mm.

  5. The carbon budget of coarse woody debris in a temperate broad-leafed secondary forest in Japan

    International Nuclear Information System (INIS)

    Jomura, M.; Dannoura, M.; Kanazawa, Y.; Kominami, Y.; Miyama, T.; Goto, Y.; Tamai, K.

    2007-01-01

    We evaluated the carbon budget of coarse woody debris (CWD) in a temperate broad-leafed secondary forest. On the basis of a field survey conducted in 2003, the mass of CWD was estimated at 9.30 tC/ha, with snags amounting to 60% of the total mass. Mean annual CWD input mass was estimated to be 0.61 tC/ha/yr by monitoring tree mortality in the forest from 1999 to 2004. We evaluated the CWD decomposition rate as the CO 2 evolution rate from CWD by measuring CO 2 emissions from 91 CWD samples (RCWD) with a closed dynamic chamber and infrared gas analysis system. The relationships between RCWD and temperature in the chamber, water content of the CWD, and other CWD characteristics were determined. By scaling the measured RCWD to the ecosystem, we estimated that the annual RCWD in the forest in 2003 was 0.50 tC/ha/yr or 10%-16% of the total heterotrophic respiration. Therefore, 0.11 tC/ha/yr or 7% of the forest net ecosystem production was sequestered by CWD. In a young forest, in which CWD input and decomposition are not balanced, the CWD carbon budget needs to be quantified for accurate evaluation of the forest carbon cycle and NEP

  6. Controls on declining carbon balance with leaf age among 10 woody species in Australian woodland: do leaves have zero daily net carbon balances when they die?

    Science.gov (United States)

    Reich, Peter B; Falster, Daniel S; Ellsworth, David S; Wright, Ian J; Westoby, Mark; Oleksyn, Jacek; Lee, Tali D

    2009-01-01

    * Here, we evaluated how increased shading and declining net photosynthetic capacity regulate the decline in net carbon balance with increasing leaf age for 10 Australian woodland species. We also asked whether leaves at the age of their mean life-span have carbon balances that are positive, zero or negative. * The net carbon balances of 2307 leaves on 53 branches of the 10 species were estimated. We assessed three-dimensional architecture, canopy openness, photosynthetic light response functions and dark respiration rate across leaf age sequences on all branches. We used YPLANT to estimate light interception and to model carbon balance along the leaf age sequences. * As leaf age increased to the mean life-span, increasing shading and declining photosynthetic capacity each separately reduced daytime carbon gain by approximately 39% on average across species. Together, they reduced daytime carbon gain by 64% on average across species. * At the age of their mean life-span, almost all leaves had positive daytime carbon balances. These per leaf carbon surpluses were of a similar magnitude to the estimated whole-plant respiratory costs per leaf. Thus, the results suggest that a whole-plant economic framework, including respiratory costs, may be useful in assessing controls on leaf longevity.

  7. Bundvands respiration i Kattegat og Bælthavet

    DEFF Research Database (Denmark)

    Hansen, Jørgen L. S.; Bendtsen, Jørgen

    Der findes generelt meget få direkte målinger af den pelagiske respiration, og det har ikke været muligt at finde repræsentative målinger af den pelagiske respiration for de åbne danske farvande. Her præsenteres et sæsonstudie af bundvandets respiration fra 5 stationer i et transekt gående fra det....... Temperaturfølsomheden af respirationsraten udtrykt som en Q10 var 3,01 ± 1.07 for alle forsøg og uafhængigt af om prøverne blev kølet eller opvarmet under inkubationerne. Den labile pulje af organisk stof blev bestemt og de observerede respirations rater svarede til specifikke kulstof omsætningsrater på mellem 0...... målbar reduktion i det partikulære materiale under inkubationerne, tyder overraskende på,at opløst organisk materiale (DOM) er den vigtigste kulstofkilde for bundvandet respiration....

  8. 42 CFR 84.1134 - Respirator containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84... Combination Gas Masks § 84.1134 Respirator containers; minimum requirements. (a) Except as provided in paragraph (b) of this section each respirator shall be equipped with a substantial, durable container...

  9. 21 CFR 892.1970 - Radiographic ECG/respirator synchronizer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic ECG/respirator synchronizer. 892.1970... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1970 Radiographic ECG/respirator synchronizer. (a) Identification. A radiographic ECG/respirator synchronizer is a device intended to be used to...

  10. A Vineyard Agroecosystem: Disturbance and Precipitation Affect Soil Respiration under Mediterranean Conditions

    Science.gov (United States)

    We investigated impacts of agricultural management practices on soil respiration (Rs) in a Cabernet sauvignon (Vitis vinifera) vineyard (Oakville, CA; November 2003 – December 2005). We determined 1) Rs’s response to cover cropping, mowing and tillage, 2) environmental drivers of Rs and 3) total ann...

  11. Respiration and carbon dynamics of free-living and particle-attached bacteria in coastal waters of NE Pacific

    Science.gov (United States)

    Guo, C.; Ke, Y.; Liu, H.

    2016-02-01

    Bacterial respiration (BR) rates are fundamental to understand the role of bacteria in carbon flow in aquatic ecosystem, and therefore it is critical to obtain reliable measurements. Prefiltration- (mostly 1-3μm) and dark-incubation- (mostly 24 h) based direct measurements of oxygen consumption have been the most commonly used method for BR. However, the prefiltration procedure and long incubation time may cause change of the bacterial abundance and structure, leading to inaccurate measurements. In this study, by measuring bacterial abundance, production and respiration of both particle-attached (PA) and free-living (FL) bacteria at two contrasting site in coastal NE Pacific from Nov 2014 to Mar 2015, we found that the 24 h growth rate of FL bacteria in the traditional BR incubations were significantly higher for 30% and 54% than those obtained for FL and total (FL+PA) bacteria in unfiltered incubations respectively, suggesting removal of protist grazers could cause a significant biomass accumulation during 24 h incubation than the in situ condition. This biomass overestimation resulted in 40% (±12%) overestimation of measured FL BR rates compared with the corrected in situ FL BR. Nevertheless, for the corrected in situ total BR, the rates were overestimated by traditional method in three measurements over nine for 6-46%, and were underestimated in the rest six measurements for 7-67%. Interestingly, those underestimations were attributed to the ignorance of PA bacteria due to prefiltration, which had larger cell size than the FL bacteria, accounted for 19% (±16%) in total bacterial abundance, and contributed to 50% (±19%) of total bacterial production. The average bacterial growth efficiency calculated by comparable 24 h integrated bacterial production and respiration was 0.42 (±0.24). Our results confirmed two major flaws in the current BR methodology, i.e., 1) it only measures the respiration of FL bacteria, and 2) the removal of grazers causing dramatic

  12. Quantifying soil respiration at landscape scales. Chapter 11

    Science.gov (United States)

    John B. Bradford; Michael G. Ryan

    2008-01-01

    Soil CO2, efflux, or soil respiration, represents a substantial component of carbon cycling in terrestrial ecosystems. Consequently, quantifying soil respiration over large areas and long time periods is an increasingly important goal. However, soil respiration rates vary dramatically in space and time in response to both environmental conditions...

  13. Dependence of fluence errors in dynamic IMRT on leaf-positional errors varying with time and leaf number

    International Nuclear Information System (INIS)

    Zygmanski, Piotr; Kung, Jong H.; Jiang, Steve B.; Chin, Lee

    2003-01-01

    ALPO is an Average Leaf Pair Opening (the concept of ALPO was previously introduced by us in Med. Phys. 28, 2220-2226 (2001). Therefore, dose errors associated with RLP errors are larger for fields requiring small leaf gaps. For an N-field IMRT plan, we demonstrate that the total fluence error (if we neglect inhomogeneities and scatter) is proportional to 1/√(N), where N is the number of fields, which slightly reduces the impact of RLP errors of individual fields on the total fluence error. We tested and applied the analytical apparatus in the context of commercial inverse treatment planning systems used in our clinics (Helios TM and BrainScan TM ). We determined the actual distribution of leaf-positional errors by studying MLC controller (Varian Mark II and Brainlab Novalis MLCs) log files created by the controller after each field delivery. The analytically derived relationship between fluence error and RLP errors was confirmed by numerical simulations. The equivalence of relative fluence error to relative dose error was verified by a direct dose calculation. We also experimentally verified the truthfulness of fluences derived from the log file data by comparing them to film data

  14. Drought-Induced Leaf Proteome Changes in Switchgrass Seedlings

    Directory of Open Access Journals (Sweden)

    Zhujia Ye

    2016-08-01

    Full Text Available Switchgrass (Panicum virgatum is a perennial crop producing deep roots and thus highly tolerant to soil water deficit conditions. However, seedling establishment in the field is very susceptible to prolonged and periodic drought stress. In this study, a “sandwich” system simulating a gradual water deletion process was developed. Switchgrass seedlings were subjected to a 20-day gradual drought treatment process when soil water tension was increased to 0.05 MPa (moderate drought stress and leaf physiological properties had expressed significant alteration. Drought-induced changes in leaf proteomes were identified using the isobaric tags for relative and absolute quantitation (iTRAQ labeling method followed by nano-scale liquid chromatography mass spectrometry (nano-LC-MS/MS analysis. Additionally, total leaf proteins were processed using a combinatorial library of peptide ligands to enrich for lower abundance proteins. Both total proteins and those enriched samples were analyzed to increase the coverage of the quantitative proteomics analysis. A total of 7006 leaf proteins were identified, and 257 (4% of the leaf proteome expressed a significant difference (p < 0.05, fold change <0.6 or >1.7 from the non-treated control to drought-treated conditions. These proteins are involved in the regulation of transcription and translation, cell division, cell wall modification, phyto-hormone metabolism and signaling transduction pathways, and metabolic pathways of carbohydrates, amino acids, and fatty acids. A scheme of abscisic acid (ABA-biosynthesis and ABA responsive signal transduction pathway was reconstructed using these drought-induced significant proteins, showing systemic regulation at protein level to deploy the respective mechanism. Results from this study, in addition to revealing molecular responses to drought stress, provide a large number of proteins (candidate genes that can be employed to improve switchgrass seedling growth and

  15. Using a Chlorophyll Meter to Evaluate the Nitrogen Leaf Content in Flue-Cured Tobacco (Nicotiana tabacum L.

    Directory of Open Access Journals (Sweden)

    Fabio Castelli

    2009-06-01

    Full Text Available In flue-cured tobacco N fertilizer is commonly applied during pre-planting, and very often applied again later as a growth-starter. It is generally held that the efficiency of N-fertilizer use can be improved by evaluating the leaf Nstatus after transplanting and until flowering stage. N use efficiency in this context does not refer merely to the yield but also to the quality, in the meanwhile minimizing the negative effects on the environment. To investigate these aspects, we evaluated the capacity of a Minolta model SPAD-502 chlorophyll meter to estimate the N-status in flue-cured tobacco. The aims was to verify if a relationship exists between SPAD readings and leaf N content, and if a single leaf, in a well defined stalk position, could represent the nitrogen content of the whole plant. During the years 1995 and 1996, a pot experiment was conducted using two flue-cured tobacco varieties. SPAD values, total chlorophyll, total N contents and leaf area were measured throughout the growing season, on each odd leaf stalk position. SPAD values were well-correlated with both total chlorophyll and total N leaf concentration, and the regression coefficients were higher when relationships were calculated on a leaf-area basis. For both relationships, SPAD-total chlorophyll and SPAD-total N, the best fittings were obtained with quadratic equations. One leaf stalk position alone is able to monitor the N-status of the whole plant during the first six weeks after transplanting, without distinction of year and variety effects. The SPAD measurement of one leaf per plant, throughout the vegetative growing season, is therefore a valid tool to test the N-status of the crop in a period when a required N supply is still effective.

  16. Effect of urdbean leaf crinkle virus infection on total soluble protein and antioxidant enzymes in blackgram plants

    International Nuclear Information System (INIS)

    Ashfaq, M.; Mughal, S.M.; Khan, A.; Javed, N.; Sahi, S.T.; Shahid, M.

    2010-01-01

    Urdbean leaf crinkle virus (ULCV) is a common, wide spread, destructive and economically important disease causing systemic infection in blackgram (Vigna mungo (L.) Hepper), resulting in extreme crinkling, curling, puckering and rugosity of leaves, and yield reductions. Effect of viral infection was investigated on total soluble proteins and antioxidant enzymes activity in two genotypes viz., Mash-88-susceptible and CM-2002-resistant, at different growth stages under both the inoculated and un-inoculated conditions. ULCV infection resulted in significant increase in total soluble protein contents of the leaves in both genotypes. In healthy plant, super oxide dismutase (SOD), catalase (CAT) and peroxidase (PO) showed similar activity levels. In inoculated plants of Mash-88, SOD and PO activities decreased and increased non-significantly at all growth stages, respectively. The activities of PO and SOD increased and decreased significantly after 15 and 30 days of inoculation in resistant genotype, respectively. No significant changes in catalase (CAT) activity were detected in ULCV-infected leaves over the control. It was concluded that the super oxide dismutase and peroxidases might be associated with resistance/susceptibility to ULCV infection. (author)

  17. Maize YABBY genes drooping leaf1 and drooping leaf2 affect agronomic traits by regulating leaf architecture

    Science.gov (United States)

    Leaf architectural traits, such as length, width and angle, directly influence canopy structure and light penetration, photosynthate production and overall yield. We discovered and characterized a maize (Zea mays) mutant with aberrant leaf architecture we named drooping leaf1 (drl1), as leaf blades ...

  18. Predicting vegetation type through physiological and environmental interactions with leaf traits: evergreen and deciduous forests in an earth system modeling framework.

    Science.gov (United States)

    Weng, Ensheng; Farrior, Caroline E; Dybzinski, Ray; Pacala, Stephen W

    2017-06-01

    Earth system models are incorporating plant trait diversity into their land components to better predict vegetation dynamics in a changing climate. However, extant plant trait distributions will not allow extrapolations to novel community assemblages in future climates, which will require a mechanistic understanding of the trade-offs that determine trait diversity. In this study, we show how physiological trade-offs involving leaf mass per unit area (LMA), leaf lifespan, leaf nitrogen, and leaf respiration may explain the distribution patterns of evergreen and deciduous trees in the temperate and boreal zones based on (1) an evolutionary analysis of a simple mathematical model and (2) simulation experiments of an individual-based dynamic vegetation model (i.e., LM3-PPA). The evolutionary analysis shows that these leaf traits set up a trade-off between carbon- and nitrogen-use efficiency at the scale of individual trees and therefore determine competitively dominant leaf strategies. As soil nitrogen availability increases, the dominant leaf strategy switches from one that is high in nitrogen-use efficiency to one that is high in carbon-use efficiency or, equivalently, from high-LMA/long-lived leaves (i.e., evergreen) to low-LMA/short-lived leaves (i.e., deciduous). In a region of intermediate soil nitrogen availability, the dominant leaf strategy may be either deciduous or evergreen depending on the initial conditions of plant trait abundance (i.e., founder controlled) due to feedbacks of leaf traits on soil nitrogen mineralization through litter quality. Simulated successional patterns by LM3-PPA from the leaf physiological trade-offs are consistent with observed successional dynamics of evergreen and deciduous forests at three sites spanning the temperate to boreal zones. © 2016 John Wiley & Sons Ltd.

  19. Relationships between root respiration rate and root morphology, chemistry and anatomy in Larix gmelinii and Fraxinus mandshurica.

    Science.gov (United States)

    Jia, Shuxia; McLaughlin, Neil B; Gu, Jiacun; Li, Xingpeng; Wang, Zhengquan

    2013-06-01

    Tree roots are highly heterogeneous in form and function. Previous studies revealed that fine root respiration was related to root morphology, tissue nitrogen (N) concentration and temperature, and varied with both soil depth and season. The underlying mechanisms governing the relationship between root respiration and root morphology, chemistry and anatomy along the root branch order have not been addressed. Here, we examined these relationships of the first- to fifth-order roots for near surface roots (0-10 cm) of 22-year-old larch (Larix gmelinii L.) and ash (Fraxinus mandshurica L.) plantations. Root respiration rate at 18 °C was measured by gas phase O2 electrodes across the first five branching order roots (the distal roots numbered as first order) at three times of the year. Root parameters of root diameter, specific root length (SRL), tissue N concentration, total non-structural carbohydrates (starch and soluble sugar) concentration (TNC), cortical thickness and stele diameter were also measured concurrently. With increasing root order, root diameter, TNC and the ratio of root TNC to tissue N concentration increased, while the SRL, tissue N concentration and cortical proportion decreased. Root respiration rate also monotonically decreased with increasing root order in both species. Cortical tissue (including exodermis, cortical parenchyma and endodermis) was present in the first three order roots, and cross sections of the cortex for the first-order root accounted for 68% (larch) and 86% (ash) of the total cross section of the root. Root respiration was closely related to root traits such as diameter, SRL, tissue N concentration, root TNC : tissue N ratio and stele-to-root diameter proportion among the first five orders, which explained up to 81-94% of variation in the rate of root respiration for larch and up to 83-93% for ash. These results suggest that the systematic variations of root respiration rate within tree fine root system are possibly due to the

  20. Leaf structural characteristics are less important than leaf chemical properties in determining the response of leaf mass per area and photosynthesis of Eucalyptus saligna to industrial-age changes in [CO2] and temperature.

    Science.gov (United States)

    Xu, Cheng-Yuan; Salih, Anya; Ghannoum, Oula; Tissue, David T

    2012-10-01

    The rise in atmospheric [CO(2)] is associated with increasing air temperature. However, studies on plant responses to interactive effects of [CO(2)] and temperature are limited, particularly for leaf structural attributes. In this study, Eucalyptus saligna plants were grown in sun-lit glasshouses differing in [CO(2)] (290, 400, and 650 µmol mol(-1)) and temperature (26 °C and 30 °C). Leaf anatomy and chloroplast parameters were assessed with three-dimensional confocal microscopy, and the interactive effects of [CO(2)] and temperature were quantified. The relative influence of leaf structural attributes and chemical properties on the variation of leaf mass per area (LMA) and photosynthesis within these climate regimes was also determined. Leaf thickness and mesophyll size increased in higher [CO(2)] but decreased at the warmer temperature; no treatment interaction was observed. In pre-industrial [CO(2)], warming reduced chloroplast diameter without altering chloroplast number per cell, but the opposite pattern (reduced chloroplast number per cell and unchanged chloroplast diameter) was observed in both current and projected [CO(2)]. The variation of LMA was primarily explained by total non-structural carbohydrate (TNC) concentration rather than leaf thickness. Leaf photosynthetic capacity (light- and [CO(2)]-saturated rate at 28 °C) and light-saturated photosynthesis (under growth [CO(2)] and temperature) were primarily determined by leaf nitrogen contents, while secondarily affected by chloroplast gas exchange surface area and chloroplast number per cell, respectively. In conclusion, leaf structural attributes are less important than TNC and nitrogen in affecting LMA and photosynthesis responses to the studied climate regimes, indicating that leaf structural attributes have limited capacity to adjust these functional traits in a changing climate.

  1. Quantitative evaluation of the protective effect of respirators

    International Nuclear Information System (INIS)

    Murata, Mikio

    1983-01-01

    The present status and related problems of the quantitative evaluation method for respirator efficiency are generally reviewed. As the introduction, the special features of various types of respirators are summarized, and the basic concept of leakage and the protection factor are explained. As for the quantitative measurement of the protective efficiency, the features of various existing man-test methods such as NaCl aerosol man-test, DOP (dioctyl phthalate) man-test, and SF 6 gas man-test are reviewed and discussed. As the important problems associated with those man-tests, the following aspects are discussed. The measurement of the aerosol concentration within masks; the calculation method for the protection factor; the effect of beards. The examples of measuring the protection factor are also explained for the following respirator systems: half mask respirator with a high efficiency filter; full face mask respirator with a high efficiency filter; demand mode and pressure-demand mode respirators; and mound suit with suspenders. Finally, the outline of the manual of respiratory protection published by NRC in 1976 is briefly reviewed. (Aoki, K.)

  2. Simplified pressure method for respirator fit testing.

    Science.gov (United States)

    Han, D; Xu, M; Foo, S; Pilacinski, W; Willeke, K

    1991-08-01

    A simplified pressure method has been developed for fit testing air-purifying respirators. In this method, the air-purifying cartridges are replaced by a pressure-sensing attachment and a valve. While wearers hold their breath, a small pump extracts air from the respirator cavity until a steady-state pressure is reached in 1 to 2 sec. The flow rate through the face seal leak is a unique function of this pressure, which is determined once for all respirators, regardless of the respirator's cavity volume or deformation because of pliability. The contaminant concentration inside the respirator depends on the degree of dilution by the flow through the cartridges. The cartridge flow varies among different brands and is measured once for each brand. The ratio of cartridge to leakflow is a measure of fit. This flow ratio has been measured on human subjects and has been compared to fit factors determined on the same subjects by means of photometric and particle count tests. The aerosol tests gave higher values of fit.

  3. Beyond leaf color: Comparing camera-based phenological metrics with leaf biochemical, biophysical, and spectral properties throughout the growing season of a temperate deciduous forest

    Science.gov (United States)

    Yang, Xi; Tang, Jianwu; Mustard, John F.

    2014-03-01

    Plant phenology, a sensitive indicator of climate change, influences vegetation-atmosphere interactions by changing the carbon and water cycles from local to global scales. Camera-based phenological observations of the color changes of the vegetation canopy throughout the growing season have become popular in recent years. However, the linkages between camera phenological metrics and leaf biochemical, biophysical, and spectral properties are elusive. We measured key leaf properties including chlorophyll concentration and leaf reflectance on a weekly basis from June to November 2011 in a white oak forest on the island of Martha's Vineyard, Massachusetts, USA. Concurrently, we used a digital camera to automatically acquire daily pictures of the tree canopies. We found that there was a mismatch between the camera-based phenological metric for the canopy greenness (green chromatic coordinate, gcc) and the total chlorophyll and carotenoids concentration and leaf mass per area during late spring/early summer. The seasonal peak of gcc is approximately 20 days earlier than the peak of the total chlorophyll concentration. During the fall, both canopy and leaf redness were significantly correlated with the vegetation index for anthocyanin concentration, opening a new window to quantify vegetation senescence remotely. Satellite- and camera-based vegetation indices agreed well, suggesting that camera-based observations can be used as the ground validation for satellites. Using the high-temporal resolution dataset of leaf biochemical, biophysical, and spectral properties, our results show the strengths and potential uncertainties to use canopy color as the proxy of ecosystem functioning.

  4. Plant growth and respiration re-visited: maintenance respiration defined – it is an emergent property of, not a separate process within, the system – and why the respiration : photosynthesis ratio is conservative

    Science.gov (United States)

    Thornley, John H. M.

    2011-01-01

    Background and Aims Plant growth and respiration still has unresolved issues, examined here using a model. The aims of this work are to compare the model's predictions with McCree's observation-based respiration equation which led to the ‘growth respiration/maintenance respiration paradigm’ (GMRP) – this is required to give the model credibility; to clarify the nature of maintenance respiration (MR) using a model which does not represent MR explicitly; and to examine algebraic and numerical predictions for the respiration:photosynthesis ratio. Methods A two-state variable growth model is constructed, with structure and substrate, applicable on plant to ecosystem scales. Four processes are represented: photosynthesis, growth with growth respiration (GR), senescence giving a flux towards litter, and a recycling of some of this flux. There are four significant parameters: growth efficiency, rate constants for substrate utilization and structure senescence, and fraction of structure returned to the substrate pool. Key Results The model can simulate McCree's data on respiration, providing an alternative interpretation to the GMRP. The model's parameters are related to parameters used in this paradigm. MR is defined and calculated in terms of the model's parameters in two ways: first during exponential growth at zero growth rate; and secondly at equilibrium. The approaches concur. The equilibrium respiration:photosynthesis ratio has the value of 0·4, depending only on growth efficiency and recycling fraction. Conclusions McCree's equation is an approximation that the model can describe; it is mistaken to interpret his second coefficient as a maintenance requirement. An MR rate is defined and extracted algebraically from the model. MR as a specific process is not required and may be replaced with an approach from which an MR rate emerges. The model suggests that the respiration:photosynthesis ratio is conservative because it depends on two parameters only whose

  5. Plant species richness regulates soil respiration through changes in productivity.

    Science.gov (United States)

    Dias, André Tavares Corrêa; van Ruijven, Jasper; Berendse, Frank

    2010-07-01

    Soil respiration is an important pathway of the C cycle. However, it is still poorly understood how changes in plant community diversity can affect this ecosystem process. Here we used a long-term experiment consisting of a gradient of grassland plant species richness to test for effects of diversity on soil respiration. We hypothesized that plant diversity could affect soil respiration in two ways. On the one hand, more diverse plant communities have been shown to promote plant productivity, which could increase soil respiration. On the other hand, the nutrient concentration in the biomass produced has been shown to decrease with diversity, which could counteract the production-induced increase in soil respiration. Our results clearly show that soil respiration increased with species richness. Detailed analysis revealed that this effect was not due to differences in species composition. In general, soil respiration in mixtures was higher than would be expected from the monocultures. Path analysis revealed that species richness predominantly regulates soil respiration through changes in productivity. No evidence supporting the hypothesized negative effect of lower N concentration on soil respiration was found. We conclude that shifts in productivity are the main mechanism by which changes in plant diversity may affect soil respiration.

  6. [The development of a respiration and temperature monitor].

    Science.gov (United States)

    Du, X; Wu, B; Liu, Y; He, Q; Xiao, J

    2001-12-01

    This paper introduces the design of a monitoring system to measure the respiration and temperature of a body with an 8Xc196 single-chip microcomputer. This system can measure and display the respiration wave, respiration frequency and the body temperature in real-time with a liquid crystal display (LCD) and give an alarm when the parameters are beyond the normal scope. In addition, this device can provide a 24 hours trend graph of the respiration frequency and the body temperature parameters measured. Data can also be exchanged through serial communication interfaces (RS232) between the PC and the monitor.

  7. Long term carbon dioxide exchange above a mixed forest in the Belgian Ardennes: evaluation of different approaches to deduce total ecosystem respiration from Eddy covariance measurements

    Science.gov (United States)

    Jérôme, Elisabeth; Aubinet, Marc; Heinesch, Bernard

    2010-05-01

    The general aim of this research is to analyze inter annual variability of carbon dioxide (CO2) fluxes exchanged by a mixed forest located at the Vielsalm experimental site in Belgium. At this site, CO2 flux measurements started in 1996 and are still going on. Thirteen complete years of measurements are thus available. Net Ecosystem Exchange (NEE) inter annual variability may be driven by gross primary productivity (GPP) or Total Ecosystem Respiration (TER), which should thus be both quantified. Using flux partitioning methods, TER is deduced from NEE measurements. GPP is then obtained by subtracting TER from NEE. Initially, a robust estimation of TER is required. This work seeks to compare two independent approaches to assess TER in order to quantify the implications on inter-annual variability. The comparison was performed on twelve complete years. TER estimates can be deduced by extrapolating to the whole day NEE measurements taken during selected night or day periods. In both case, the extrapolation is performed by using a respiration response to temperature. The first approach, referred as the night-time approach, consisted in calculating TER using a temperature response function derived from night-time data sets (Reichstein et al., 2005). The second approach, referred as the daytime approach, consisted in assessing TER from the intercept of the NEE/Photosynthetically Photon Flux Density (PPFD) response (Wohlfahrt et al., 2005). For each approach, different modalities were compared: the use of long term (annual) or short term (15 days) data sets for the night-time approach and the use of different types of regression for the daytime approach. In addition, the impact of the temperature choice was studied for each of the approaches. For the night-time approach, main results showed that air temperature sensitivity of ecosystem respiration derived from annual data did not reflect the short-term air temperature sensitivity. Vielsalm is a summer active ecosystem

  8. Leaf Surface Effects on Retrieving Chlorophyll Content from Hyperspectral Remote Sensing

    Science.gov (United States)

    Qiu, Feng; Chen, JingMing; Ju, Weimin; Wang, Jun; Zhang, Qian

    2017-04-01

    Light reflected directly from the leaf surface without entering the surface layer is not influenced by leaf internal biochemical content. Leaf surface reflectance varies from leaf to leaf due to differences in the surface roughness features and is relatively more important in strong absorption spectral regions. Therefore it introduces dispersion of data points in the relationship between biochemical concentration and reflectance (especially in the visible region). Separation of surface from total leaf reflection is important to improve the link between leaf pigments content and remote sensing data. This study aims to estimate leaf surface reflectance from hyperspectral remote sensing data and retrieve chlorophyll content by inverting a modified PROSPECT model. Considering leaf surface reflectance is almost the same in the visible and near infrared spectral regions, a surface layer with a reflectance independent of wavelength but varying from leaf to leaf was added to the PROSPECT model. The specific absorption coefficients of pigments were recalibrated. Then the modified model was inverted on independent datasets to check the performance of the model in predicting the chlorophyll content. Results show that differences in estimated surface layer reflectance of various species are noticeable. Surface reflectance of leaves with epicuticular waxes and trichomes is usually higher than other samples. Reconstruction of leaf reflectance and transmittance in the 400-1000 nm wavelength region using the modified PROSPECT model is excellent with low root mean square error (RMSE) and bias. Improvements for samples with high surface reflectance (e.g. maize) are significant, especially for high pigment leaves. Moreover, chlorophyll retrieved from inversion of the modified model is consequently improved (RMSE from 5.9-13.3 ug/cm2 with mean value 8.1 ug/cm2, while mean correlation coefficient is 0.90) compared to results of PROSPECT-5 (RMSE from 9.6-20.2 ug/cm2 with mean value 13

  9. Effect of the Storage Temperature, Duration and Gamma Irradiation on the Respiration Rate and Sugar Content of Minituber 'Superior'

    International Nuclear Information System (INIS)

    Lim, J.H.; Hwangbo, J.K.; Baek, M.H.; Kim, J.H.; Kim, J.S.; Lee, M.C.

    2005-01-01

    This study was to evaluate whether ionizing gamma radiation could be applied to break the dormancy of a potato minituber. The respiration rate of the minitubers was significantly affected by the storage temperature and a low dose gamma radiation. Ionizing radiation of 8 Gy enhanced the respiration rate of the potato tuber stored at 10°C for 20 days. The potato tuber subjected to 4 and 8 Gy after 40 days storage at 10 and 10°C exhibited higher respiration rates compared to the control (non-irradiated), but not at st. However, the ionizing radiation did not exhibit on significant effect on the respiration rate of the potato tuber stored for 60 days. It was observed that minitubers stored for 20 days had significant response to the storage temperature in terms of the total sugar content the higher the storage temperature, the lower the total sugar content. It was measured that the reducing sugar content was increased under the storage conditions both 5 and 10°C for 40 days, but not to 20°C. The total sugar contents in the minituber stored for 60 days were similar to those stored for 40 days. The data was discussed on the relationships among the storage duration, temperature and ionizing radiation. (author)

  10. Lessons from simultaneous measurements of soil respiration and net ecosystem exchange of CO2 in temperate forests

    Science.gov (United States)

    Renchon, A.; Pendall, E.

    2017-12-01

    findings underscore the value of continuous measurements of RS in flux tower footprints. Findings are also relevant to recent research on light inhibition of leaf respiration and contribute to improved understanding of ecosystem carbon cycle - climate feedback processes.

  11. [Effects of management regime on soil respiration from agroecosystems].

    Science.gov (United States)

    Chen, Shu-tao; Zhu, Da-wei; Niu, Chuan-po; Zou, Jian-wen; Wang, Chao; Sun, Wen-juan

    2009-10-15

    In order to examine the effects of management regime, such as nitrogen application and plowing method, on soil respiration from farmland, the static opaque chamber-gas chromatograph method was used to measure soil CO2 fluxes in situ. The field measurement was carried out for 5 growing seasons, which were the 2002-2003 wheat, 2003 maize and soybean, 2003-2004 wheat, 2004 maize and 2004-2005 wheat seasons. Our results showed that soil respiration increased in fertilizer-applied treatments compared with no fertilizer treatment after 3 times of fertilizer application on 9 November 2002, 14 February and 26 March 2003. And the most obvious increase appeared following the third fertilizer application. No significant difference in soil respiration was found among several fertilizer application treatments. The effect of plowing depth on soil respiration was contingent on preceding cropping practice. Over the 2003-2004 wheat-growing seasons (its preceding cropping practice was rice paddy), mean soil respiration rates were not significant different (p > 0.05) between no plowing treatment and shallow plowing treatment. The shallow plowing treatment CT2 led to higher soil CO2 losses compared with no plowing treatment of NT2 in the 2004 maize-growing season, however, the significant higher (p soil respiration rates occurred with no plowing treatment of NT3 in the following 2004-2005 wheat-growing season. Intensive plowing (25 cm depth), compared with no plowing practice (NT4), increased soil respiration significantly during the 2004-2005 wheat-growing season. Regression analysis showed that the exponential function could be employed to fit the relationship between soil respiration and temperature. The exponential relationship yielded the Q10 values which were varied from 1.26 to 3.60, with a mean value of 2.08. To evaluate the effect of temperature on soil respiration, the CO2 emission fluxes were normalized for each treatment and each crop growing season. Plotting the

  12. Respirators: APR Issuer Self Study 33461

    Energy Technology Data Exchange (ETDEWEB)

    Chochoms, Michael [Los Alamos National Laboratory

    2016-07-13

    Respirators: APR Issuer Self-Study (course 33461) is designed to introduce and familiarize employees selected as air-purifying respirator (APR) issuers at Los Alamos National Laboratory (LANL) with the responsibilities, limitations, procedures, and resources for issuing APRs at LANL. The goal is to enable these issuers to consistently provide proper, functioning APRs to authorized users

  13. Evaluation of Microdesmis puberula leaf meal as feed ingredient in ...

    African Journals Online (AJOL)

    The material was milled using a hammer mill to produce the leaf meal. Microdesmis puberula leaf meal contain 17.32% crude protein, 6.52% ether extract, 12.25% total ash, 24.84% crude fibre, 24.06% NFE and an appreciable percent of minerals. Three broiler starter diets were formulated to contain the meal at dietary ...

  14. Development of conformal respirator monitoring technology

    International Nuclear Information System (INIS)

    Shonka, J.J.; Weismann, J.J.; Logan, R.J.

    1997-04-01

    This report summarizes the results of a Small Business Innovative Research Phase II project to develop a modular, surface conforming respirator monitor to improve upon the manual survey techniques presently used by the nuclear industry. Research was performed with plastic scintillator and gas proportional modules in an effort to find the most conducive geometry for a surface conformal, position sensitive monitor. The respirator monitor prototype developed is a computer controlled, position-sensitive detection system employing 56 modular proportional counters mounted in molds conforming to the inner and outer surfaces of a commonly used respirator (Scott Model 801450-40). The molds are housed in separate enclosures and hinged to create a open-quotes waffle-ironclose quotes effect so that the closed monitor will simultaneously survey both surfaces of the respirator. The proportional counter prototype was also designed to incorporate Shonka Research Associates previously developed charge-division electronics. This research provided valuable experience into pixellated position sensitive detection systems. The technology developed can be adapted to other monitoring applications where there is a need for deployment of many traditional radiation detectors

  15. Redefinition and global estimation of basal ecosystem respiration rate

    DEFF Research Database (Denmark)

    Yuan, Wenping; Luo, Yiqi; Li, Xianglan

    2011-01-01

    Basal ecosystem respiration rate (BR), the ecosystem respiration rate at a given temperature, is a common and important parameter in empirical models for quantifying ecosystem respiration (ER) globally. Numerous studies have indicated that BR varies in space. However, many empirical ER models sti...

  16. Respirable dust measured downwind during rock dust application.

    Science.gov (United States)

    Harris, M L; Organiscak, J; Klima, S; Perera, I E

    2017-05-01

    The Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health (NIOSH) conducted underground evaluations in an attempt to quantify respirable rock dust generation when using untreated rock dust and rock dust treated with an anticaking additive. Using personal dust monitors, these evaluations measured respirable rock dust levels arising from a flinger-type application of rock dust on rib and roof surfaces. Rock dust with a majority of the respirable component removed was also applied in NIOSH's Bruceton Experimental Mine using a bantam duster. The respirable dust measurements obtained downwind from both of these tests are presented and discussed. This testing did not measure miners' exposure to respirable coal mine dust under acceptable mining practices, but indicates the need for effective continuous administrative controls to be exercised when rock dusting to minimize the measured amount of rock dust in the sampling device.

  17. Alpha-glucosidase Inhibitory and Antioxidant Potential of Antidiabetic Herb Alternanthera sessilis: Comparative Analyses of Leaf and Callus Solvent Fractions.

    Science.gov (United States)

    Chai, Tsun-Thai; Khoo, Chee-Siong; Tee, Chong-Siang; Wong, Fai-Chu

    2016-01-01

    Alternanthera sessilis is a medicinal herb which is consumed as vegetable and used as traditional remedies of various ailments in Asia and Africa. This study aimed to investigate the antiglucosidase and antioxidant activity of solvent fractions of A. sessilis leaf and callus. Leaf and callus methanol extracts were fractionated to produce hexane, chloroform, ethyl acetate, butanol, and water fractions. Antiglucosidase and 1,1-diphenyl-2-picrylhydrazyl scavenging activities as well as total phenolic (TP), total flavonoid (TF), and total coumarin (TC) contents were evaluated. Lineweaver-Burk plot analysis was performed on leaf and callus fractions with the strongest antiglucosidase activity. Leaf ethyl acetate fraction (LEF) had the strongest antiglucosidase (EC 50 0.55 mg/mL) and radical scavenging (EC 50 10.81 μg/mL) activity among leaf fractions. Callus ethyl acetate fraction (CEF) and chloroform fraction had the highest antiglucosidase (EC 50 0.25 mg/mL) and radical scavenging (EC 50 34.12 μg/mL) activity, respectively, among callus fractions. LEF and CEF were identified as noncompetitive and competitive α-glucosidase inhibitors, respectively. LEF and CEF had greater antiglucosidase activity than acarbose. Leaf fractions had higher phytochemical contents than callus fractions. LEF had the highest TP, TF, and TC contents. Antiglucosidase and antioxidant activities of leaf fractions correlated with phytochemical contents. LEF had potent antiglucosidase activity and concurrent antioxidant activity. CEF had the highest antiglucosidase activity among all fractions. Callus culture is a promising tool for enhancing production of potent α-glucosidase inhibitors. Leaf ethyl acetate fraction (LEF) had the strongest antiglucosidase (EC 50 0.55 mg/mL) and radical scavenging (EC 50 10.81 μg/mL) activity among leaf fractionsCallus ethyl acetate fraction (CEF) and chloroform fraction had the highest antiglucosidase (EC 50 0.25 mg/mL) and radical scavenging (EC 50 34.12

  18. Short Communication: HIV Patient Systemic Mitochondrial Respiration Improves with Exercise.

    Science.gov (United States)

    Kocher, Morgan; McDermott, Mindy; Lindsey, Rachel; Shikuma, Cecilia M; Gerschenson, Mariana; Chow, Dominic C; Kohorn, Lindsay B; Hetzler, Ronald K; Kimura, Iris F

    2017-10-01

    In HIV-infected individuals, impaired mitochondrial function may contribute to cardiometabolic disease as well as to fatigue and frailty. Aerobic exercise improves total body energy reserves; however, its impact at the cellular level is unknown. We assessed alterations in cellular bioenergetics in peripheral blood mononuclear cells (PBMC) before and after a 12-week aerobic exercise study in sedentary HIV-infected subjects on stable antiretroviral therapy who successfully completed a 12-week aerobic exercise program. In this prospective study, participants underwent supervised 20-40 min of light aerobic exercise (walking or jogging) performed three times per week for 12 weeks, gradually increasing to maintain an intensity of 50%-80% of heart rate reserve. Maximal aerobic capacity (VO 2MAX ) was assessed by a graded exercise test on a cycle ergometer before and after completion of the study. PBMC from compliant subjects (attended at least 70% of exercise sessions) were assessed for mitochondrial respiration using the Seahorse XF24 Bio-Analyzer. Seven of 24 enrolled subjects were compliant with the exercise regimen. In these individuals, a significant increase (p = .04) in VO 2MAX over 12 weeks was found with a median increase of 14%. During the same interval, a 2.45-fold increase in PBMC mitochondrial respiratory capacity (p = .04), a 5.65-fold increase in spare respiratory capacity (p = .01), and a 3.15-fold (p = .04) increase in nonmitochondrial respiration was observed. Aerobic exercise improves respiration at the cellular level. The diagnostic and prognostic value of such improved cellular respiration in the setting of chronic HIV warrants further investigation.

  19. Extraction of antioxidant pigments from dye sorghum leaf sheaths

    NARCIS (Netherlands)

    Kayode, A.P.P.; Bara, C.A.; Dalode-Vieira, G.; Linnemann, A.R.; Nout, M.J.R.

    2012-01-01

    Extraction of antioxidant biocolorant pigments from leaf sheaths of dye sorghum was optimized. Effects of temperature and ethanol concentration of the extraction solvent on the concentrations of the 3-deoxyanthocyanidins, total phenolics and total anthocyanins, and the colour parameters of the

  20. A Global Database of Soil Respiration Data, Version 2.0

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set provides an updated soil respiration database (SRDB), a near-universal compendium of published soil respiration (RS) data. Soil respiration,...

  1. Implications of CO2 pooling on δ13C of ecosystem respiration and leaves in Amazonian forest

    Science.gov (United States)

    de Araújo, A. C.; Ometto, J. P. H. B.; Dolman, A. J.; Kruijt, B.; Waterloo, M. J.; Ehleringer, J. R.

    2007-11-01

    The carbon isotope of a leaf (δ13Cleaf) is generally more negative in riparian zones than in areas with low soil moisture content or rainfall input. In Central Amazonia, the small-scale topography is composed of plateaus and valleys, with plateaus generally being drier than the valley edges in the dry season. The nocturnal accumulation of CO2 is higher in the valleys than on the plateaus in the dry season. The CO2 stored in the valleys takes longer to be released than that on the plateaus, and sometimes the atmospheric CO2 concentration (ca) does not drop to the same level as on the plateaus at any time during the day. Samples of sunlit leaves and atmospheric air were collected along a topographical gradient to test whether the δ13Cleaf of sunlit leaves and the carbon isotope ratio of ecosystem respired CO2 (δ13CR) may be more negative in the valley than those on the plateau. The δ13Cleaf was significantly more negative in the valley than on the plateau. Factors considered to be driving the observed variability in δ13Cleaf were: leaf nitrogen concentration, leaf mass per unit area (LMA), soil moisture availability, more negative carbon isotope ratio of atmospheric CO2 (δ13Ca) in the valleys during daytime hours, and leaf discrimination (Δleaf). The observed pattern of δ13Cleaf suggests that water-use efficiency (WUE) may be higher on the plateaus than in the valleys. The ;13CR was more negative in the valleys than on the plateaus on some nights, whereas in others it was not. It is likely that lateral drainage of CO2 enriched in 13C from upslope areas might have happened when the nights were less stable. Biotic factors such as soil CO2 efflux (Rsoil) and the responses of plants to environmental variables such as vapor pressure deficit (D) may also play a role.

  2. Mitochondrial Respiration and Oxygen Tension.

    Science.gov (United States)

    Shaw, Daniel S; Meitha, Karlia; Considine, Michael J; Foyer, Christine H

    2017-01-01

    Measurements of respiration and oxygen tension in plant organs allow a precise understanding of mitochondrial capacity and function within the context of cellular oxygen metabolism. Here we describe methods that can be routinely used for the isolation of intact mitochondria, and the determination of respiratory electron transport, together with techniques for in vivo determination of oxygen tension and measurement of respiration by both CO 2 production and O 2 consumption that enables calculation of the respiratory quotient [CO 2 ]/[O 2 ].

  3. Thermal adaptation of heterotrophic soil respiration in laboratory microcosms.

    Science.gov (United States)

    Mark A. Bradford; Brian W. Watts; Christian A. Davies

    2010-01-01

    Respiration of heterotrophic microorganisms decomposing soil organic carbon releases carbon dioxide from soils to the atmosphere. In the short term, soil microbial respiration is strongly dependent on temperature. In the long term, the response of heterotrophic soil respiration to temperature is uncertain. However, following established evolutionary tradeoffs, mass-...

  4. A Global Database of Soil Respiration Data, Version 1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set provides a soil respiration data database (SRDB), a near-universal compendium of published soil respiration (RS) data. Soil respiration, the...

  5. Respirators: Air Purifying, Self-Study, Course 40723

    Energy Technology Data Exchange (ETDEWEB)

    Chochoms, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-12-21

    Respirators: Air Purifying Self-Study (COURSE 40723) is designed for Los Alamos National Laboratory (LANL) workers, support services subcontractors, and other LANL subcontractors who work under the LANL Respiratory Protection Program (RPP). This course also meets the air-purifying respirators (APRs) retraining requirement.

  6. Short-term Effect of Nitrogen Addition on Microbial and Root Respiration in an Alpine Spruce Ecosystem

    Directory of Open Access Journals (Sweden)

    Jian Wang1

    2017-03-01

    Full Text Available Soil respiration plays an important role in the carbon (C flux of the global C cycle and is greatly affected by nitrogen (N additions in the form of deposition or fertilization. The aim of this study was to investigate the response of total soil respiration (Rs, microbial respiration (Rm, and root respiration (Rr to short-term N addition and the potential mechanisms of short-term N deposition influencing soil respiration in an alpine spruce ecosystem. Four N treatment levels (0, 50, 100, 150 kg N ha-1 year-1 were applied monthly in a Picea balfouriana (commonly known as "alpine spruce" plantation beginning in November 2013 and Rs, Rm, and Rr were measured from May to November 2014. The results show that simulated N depositions stimulate Rs, Rm, and Rr and the beneficial effects decreased along N gradients from hourly to seasonal scales. The seasonal temperature coefficients (Q10 of Rs, Rm, and Rr ranged from 2.50 to 3.8, 2.99 to 4.63, and 1.86 to 2.96, while the diurnal Q10 ranged from 1.71 to 2.04, 1.89 to 2.32, 1.42 to 1.75, and there was a similar trend with soil respiration along N gradients. In addition, Rr showed significant positive correlation with fine root biomass, and Rm was likely driven by soil enzyme related to the microbial C cycle in the growing season. Our results indicate that short-term N addition stimulated fine root biomass and soil enzymatic activity to bring about a potential increase in soil respiration rates under low-N addition, while the opposite occurred under high-N addition.

  7. Leaf size indices and structure of the peat swamp forest

    Directory of Open Access Journals (Sweden)

    L.G. Aribal

    2017-12-01

    Full Text Available Leaf size indices of the tree species in the peatland of Agusan del Sur in Mindanao in Philippines was examined to deduce the variation of forest structure and observed forest zonation.  Using raunkiaer and webb’s leaf size classification, the leaf morphometrics of seven tree species consistently found on the established sampling plots were determined.  The species includes Ternstroemia philippinensis Merr., Polyscias aherniana Merr. Lowry and G.M. Plunkett, Calophyllum sclerophyllum Vesque, Fagraea racemosa Jack, Ilex cymosa Blume, Syzygium tenuirame (Miq. Merr. and Tristaniopsis micrantha Merr. Peter G.Wilson and J.T.Waterh.The LSI were correlated against the variables of the peat physico-chemical properties (such as bulk density, acrotelm thickness, peat depth, total organic carbon, nitrogen, phosphorus, and potassium, pH; water (pH, ammonium, nitrate, phosphate; and leaf tissue elements (nitrogen, phosphorus and potassium.  Result showed a decreasing leaf size indices and a three leaf size category consisting of mesophyllous, mesophyllous-notophyllous and microphyllous were observed which corresponds to the structure of vegetation i.e., from the tall-pole forest having the biggest average leaf area of 6,142.29 mm2 to the pygmy forest with average leaf area of 1,670.10 mm2.  Such decreased leaf size indices were strongly correlated to soil nitrogen, acrotelm thickness, peat depth, phosphate in water, nitrogen and phosphorus in the plant tissue.

  8. Effects of experimental warming and nitrogen addition on soil respiration and CH4 fluxes from crop rotations of winter wheat–soybean/fallow

    DEFF Research Database (Denmark)

    Liu, L; Hu, C; Yang, P

    2015-01-01

    Soil respiration and CH4 emissions play a significant role in the global carbon balance. However, in situ studies in agricultural soils on responses of soil respiration and CH4 fluxes to climate warming are still sparse, especially from long-term studies with year-round heating. A warming...... by affecting soil NH4 concentration. Across years, CH4 emissions were negatively correlated with soil temperature in N1 treatment. Soil respiration showed clear seasonal fluctuations, with the largest emissions during summer and smallest in winter. Warming and nitrogen fertilization had no significant effects...... on total cumulative soil CO2 fluxes. Soil respiration was positively correlated with microbial biomass C, and microbial biomass C was not affected significantly by warming or nitrogen addition. The lack of significant effects of warming on soil respiration may have resulted from: (1) warming-induced soil...

  9. "Breath figures" on leaf surfaces-formation and effects of microscopic leaf wetness.

    Science.gov (United States)

    Burkhardt, Juergen; Hunsche, Mauricio

    2013-01-01

    "Microscopic leaf wetness" means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 μm, microscopic leaf wetness is about two orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the type and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g., ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past.

  10. The leaf size-twig size spectrum in evergreen broadleaved forest of ...

    African Journals Online (AJOL)

    Compared to deciduous broad-leaved species, the evergreen broad-leaved species were smaller in total leaf area for a given cross-sectional area or stem mass. This suggests that the species would support less leaf area at a given twig cross-sectional area with increasing environmental stress. And the life form can modify ...

  11. Sheep fed with banana leaf hay reduce ruminal protozoa population.

    Science.gov (United States)

    Freitas, Cláudio Eduardo Silva; Duarte, Eduardo Robson; Alves, Dorismar David; Martinele, Isabel; D'Agosto, Marta; Cedrola, Franciane; de Moura Freitas, Angélica Alves; Dos Santos Soares, Franklin Delano; Beltran, Makenzi

    2017-04-01

    A ciliate protozoa suppression can reduce methane production increasing the energy efficiency utilization by ruminants. The physicochemical characteristics of rumen fluid and the profile of the rumen protozoa populations were evaluated for sheep fed banana leaf hay in replacement of the Cynodon dactylon cv. vaqueiro hay. A total of 30 male sheep were raised in intensive system during 15 days of adaptation and 63 days of experimental period. The animals were distributed in a completely randomized design that included six replicates of five treatments with replacement levels (0, 25, 50, 75, and 100%) of the grass vaquero for the banana leaf hay. Samples of fluid were collected directly from the rumen with sterile catheters. Color, odor, viscosity, and the methylene blue reduction potential (MBRP) were evaluated and pH estimated using a digital potentiometer. After decimal dilutions, counts of genus protozoa were performed in Sedgewick Rafter chambers. The averages of pH, MBRP, color, odor, and viscosity were not influenced by the inclusion of the banana leaf hay. However, the total number of protozoa and Entodinium spp. population significantly decreased at 75 and 100% inclusions of banana leaf hay as roughage.

  12. Banana leaf and glucose mineralization and soil organic matter in microhabitats of banana plantations under long-term pesticide use.

    Science.gov (United States)

    Blume, Elena; Reichert, José Miguel

    2015-06-01

    Soil organic matter (SOM) and microbial activity are key components of soil quality and sustainability. In the humid tropics of Costa Rica 3 pesticide regimes were studied-fungicide (low input); fungicide and herbicide (medium input); and fungicide, herbicide, and nematicide (high input)-under continuous banana cultivation for 5 yr (young) or 20 yr (old) in 3 microhabitats-nematicide ring around plants, litter pile of harvested banana, and bare area between litter pile and nematicide ring. Soil samples were incubated sequentially in the laboratory: unamended, amended with glucose, and amended with ground banana leaves. Soil organic matter varied with microhabitat, being greatest in the litter pile, where microbes had the greatest basal respiration with ground banana leaf, whereas microbes in the nematicide ring had the greatest respiration with glucose. These results suggest that soil microbes adapt to specific microhabitats. Young banana plantations had similar SOM compared with old plantations, but the former had greater basal microbial respiration in unamended and in glucose-amended soil and greater first-order mineralization rates in glucose-amended soil, thus indicating soil biological quality decline over time. High pesticide input did not decrease microbial activity or mineralization rate in surface soil. In conclusion, microbial activity in tropical volcanic soil is highly adaptable to organic and inorganic inputs. © 2015 SETAC.

  13. Effect of Plant Growth Regulators on Leaf Number, Leaf Area and Leaf Dry Matter in Grape

    Directory of Open Access Journals (Sweden)

    Zahoor Ahmad BHAT

    2011-03-01

    Full Text Available Influence of phenylureas (CPPU and brassinosteriod (BR along with GA (gibberellic acid were studied on seedless grape vegetative characteristics like leaf number, leaf area and leaf dry matter. Growth regulators were sprayed on the vines either once (7 days after fruit set or 15 days after fruit set or twice (7+15 days after fruit set. CPPU 2 ppm+BR 0.4 ppm+GA 25 ppm produced maximum number of leaves (18.78 while as untreated vines produced least leaf number (16.22 per shoot. Maximum leaf area (129.70 cm2 and dry matter content (26.51% was obtained with higher CPPU (3 ppm and BR (0.4 ppm combination along with GA 25 ppm. Plant growth regulators whether naturally derived or synthetic are used to improve the productivity and quality of grapes. The relatively high value of grapes justifies more expensive inputs. A relatively small improvement in yield or fruit quality can justify the field application of a very costly product. Application of new generation growth regulators like brassinosteroids and phenylureas like CPPU have been reported to increase the leaf number as well as leaf area and dry matter thereby indirectly influencing the fruit yield and quality in grapes.

  14. Models for leaf area estimation in dwarf pigeon pea by leaf dimensions

    Directory of Open Access Journals (Sweden)

    Rafael Vieira Pezzini

    2018-03-01

    Full Text Available ABSTRACT This study aims to determine the most suitable model to estimate the leaf area of dwarf pigeon pea in function of the leaf central leaflet dimension. Six samplings of 200 leaves were performed in the first experiment, at 36, 42, 50, 56, 64, and 72 days after emergence (DAE. In the second experiment, seven samplings of 200 leaves were performed at 29, 36, 43, 49, 57, 65, and 70 DAE, totaling 2600 leaves. The length (L and width (W of the central leaflet were measured in all leaves composed by left, central, and right leaflets, the product of length times width (LW was calculated, and the leaf area (Y – sum of left, central, and right leaflet areas was determined by digital images. Linear, power, quadratic, and cubic models of Y as function of L, W, and LW were built using data from the second experiment. Leaves from the first experiment were used to validate the models. In dwarf pigeon pea, the linear (Ŷ = – 0.4088 + 1.6669x, R2 = 0.9790 is preferable, but power (Ŷ = 1.6097x1.0065, R2 = 0.9766, quadratic (Ŷ = – 0.3625 + 1.663x + 0.00007x2, R2 = 0.9790, and cubic (Ŷ = 0.7216 + 1.522x + 0.005x2 – 5E–05x3, R2 = 0.9791 models in function of LW are also suitable to estimate the leaf area obtained by digital images. The power model (Ŷ = 5.2508x1.7868, R2 = 0.95 based on the central leaflet width is less laborious because requires only one variable, but it presents accuracy reduction.

  15. The effect of air pollution and other environmental stressors on leaf fluctuating asymmetry and specific leaf area of Salix alba L

    Energy Technology Data Exchange (ETDEWEB)

    Wuytack, Tatiana, E-mail: tatiana.wuytack@ua.ac.be [Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Wuyts, Karen, E-mail: karen.wuyts@ugent.be [Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Laboratory of Forestry, Department of Forest and Water Management, Ghent University, Geraardsbergsesteenweg 267, B-9090 Gontrode (Melle) (Belgium); Van Dongen, Stefan, E-mail: stefan.vandongen@ua.ac.be [Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Baeten, Lander, E-mail: lander.baeten@ugent.be [Laboratory of Forestry, Department of Forest and Water Management, Ghent University, Geraardsbergsesteenweg 267, B-9090 Gontrode (Melle) (Belgium); Kardel, Fatemeh, E-mail: fatemeh.kardel@ua.ac.be [Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Verheyen, Kris, E-mail: kris.verheyen@ugent.be [Laboratory of Forestry, Department of Forest and Water Management, Ghent University, Geraardsbergsesteenweg 267, B-9090 Gontrode, Melle (Belgium); Samson, Roeland, E-mail: roeland.samson@ua.ac.be [Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2011-10-15

    We aimed at evaluating the effect of low-level air pollution on leaf area fluctuating asymmetry (FAA) and specific leaf area (SLA) of Salix alba L., taking into account other environmental factors. Cuttings were grown in standardized conditions in the near vicinity of air quality measuring stations in Belgium. Variability of SLA and FAA between measuring stations explained 83% and 7.26%, respectively, of the total variability. FAA was not influenced by air pollution or environmental factors such as shading, herbivory, air temperature and humidity. SLA was increased by an increase in shadow, while NO{sub x} and O{sub 3} concentrations had only a marginal influence. The influence of SO{sub 2} concentration was negligible. Although our data analysis suggests a relationship between SLA and NO{sub x}/O{sub 3} concentration, the absence of a straightforward relationship between FAA and SLA and air pollution still questions the usefulness of these bio-indicators for monitoring air pollution. - Highlights: > Leaf characteristics of white willow as possible bio-indicators for air quality. > Fluctuating asymmetry is not a good bio-indicator for monitoring the air quality. > Shadow increases specific leaf area. > NO{sub x} and O{sub 3} change specific leaf area of white willow. - Specific leaf area of S. alba increased with increasing shade and, in less extent, with increasing NO{sub x} and decreasing O{sub 3} concentration, while leaf asymmetry did not respond to air pollution

  16. The effect of air pollution and other environmental stressors on leaf fluctuating asymmetry and specific leaf area of Salix alba L

    International Nuclear Information System (INIS)

    Wuytack, Tatiana; Wuyts, Karen; Van Dongen, Stefan; Baeten, Lander; Kardel, Fatemeh; Verheyen, Kris; Samson, Roeland

    2011-01-01

    We aimed at evaluating the effect of low-level air pollution on leaf area fluctuating asymmetry (FAA) and specific leaf area (SLA) of Salix alba L., taking into account other environmental factors. Cuttings were grown in standardized conditions in the near vicinity of air quality measuring stations in Belgium. Variability of SLA and FAA between measuring stations explained 83% and 7.26%, respectively, of the total variability. FAA was not influenced by air pollution or environmental factors such as shading, herbivory, air temperature and humidity. SLA was increased by an increase in shadow, while NO x and O 3 concentrations had only a marginal influence. The influence of SO 2 concentration was negligible. Although our data analysis suggests a relationship between SLA and NO x /O 3 concentration, the absence of a straightforward relationship between FAA and SLA and air pollution still questions the usefulness of these bio-indicators for monitoring air pollution. - Highlights: → Leaf characteristics of white willow as possible bio-indicators for air quality. → Fluctuating asymmetry is not a good bio-indicator for monitoring the air quality. → Shadow increases specific leaf area. → NO x and O 3 change specific leaf area of white willow. - Specific leaf area of S. alba increased with increasing shade and, in less extent, with increasing NO x and decreasing O 3 concentration, while leaf asymmetry did not respond to air pollution

  17. Leucocyte profile and offspring production of guinea pig (Cavia cobaya given Anredera cordifolia leaf extract

    Directory of Open Access Journals (Sweden)

    D. Wijayanti

    2018-03-01

    Full Text Available The objective of this study was to determine leucocyte and offspring production of guinea pig (Cavia cobaya giving Anredera cordifolia leaf extract. Materials used were female 16 heads of guinea pig with body weight of 425g. The treatments were an extract of A. cordifolia leaf at doses of 0, 10, 50 and 90 mg/head, designated as T0, T1, T2 and T3, respectively. A. cordifolia leaf extract was administered orally from 10 days prepartum to 10 days postpartum. Blood was taken at 10 days prepartum and 10 days postpartum. Total birth of the offspring was observed. Data were analyzed by analysis of variance and if there was effect of treatment, then continued with Duncan multiple range test and Chi-Square test for fetal production between the given A. cordifolia leaf extract and control. The result showed that there was no significant difference for 10 days prepartum after addition of A cordifolia leaf extract treatment. The postpartum treated showed a total 50 mg/head level increaed for monocytes than that of level 0, 10 and 90 mg/head. Ten days postpartum treatment showed the total increase for leucocyte and monocytes total were 50 and 90 mg/head, respectively compared to 10 mg/head level. Total lymphocyte of 90 mg/head increased compared to level 10 and 50 mg/head. The highest total neutrophil as found at level of 50 mg/head which increased compared to the level of 0 and 10 mg/head. ProvisioningA. cordifolialeaf extract at doses level of 50 and 90 mg/head could increase litter size (P<0.05; χ2=9.267 and decreased offspring mortality (P<0.05; χ2=6.4. In conclusion, by giving 50 mg/head A. cordifolia leaf extract could increase leucocyte profile and offspring production of guinea pig.

  18. Transcriptional regulation of respiration in yeast metabolizing differently repressive carbon substrates

    OpenAIRE

    Fendt, Sarah-Maria; Sauer, Uwe

    2010-01-01

    Abstract Background Depending on the carbon source, Saccharomyces cerevisiae displays various degrees of respiration. These range from complete respiration as in the case of ethanol, to almost complete fermentation, and thus very low degrees of respiration on glucose. While many key regulators are known for these extreme cases, we focus here on regulators that are relevant at intermediate levels of respiration. Results We address this question by linking the functional degree of respiration t...

  19. How much work is expended for respiration?

    Science.gov (United States)

    Johnson, A T

    1993-01-01

    The rate of work expended to move air in the respiratory system has been determined for five different airflow waveshapes, a non-linear respiratory model and five exercise levels. As expected, the rectangular waveshape was the most efficient. Model conditions were then changed one a time: (i) starting lung volume was allowed to vary, (ii) exhalation flow limitation was added, (iii) respiration was considered to be a metabolic burden determining part of the ventilation requirement and (iv) a respirator mask was added. Although there is no direct work advantage to varying initial lung volume, such volume changes appear to be dictated by the asymmetry of lung recoil pressure about the lung relaxation volume; allowing the work of respiration to become a metabolic burden clearly shows why respiratory waveforms change from rest to exercise; and, adding a respirator imposes a severe respiratory burden on the wearer engaging in moderate, heavy and very heavy exercise.

  20. Leaf litter and roots as sources of mineral soil organic matter in temperate deciduous forest with and without earthworms

    Science.gov (United States)

    Fahey, T.; Yavitt, J. B.

    2012-12-01

    We labeled sugar maple trees with 13C to quantify the separate contributions of decaying leaf litter and root turnover/rhizosphere C flux to mineral soil organic matter (SOM). Labeled leaf litter was applied to forest plots with and without earthworms and recovery of the label in SOM was quantified over three years. In parallel, label recovery was quantified in soils from the labeling chambers where all label was supplied by belowground C flux. In the absence of earthworms about half of the label added as leaf litter remained in the surface organic horizons after three years, with about 3% recovered in mineral SOM. The label was most enriched on silt + clay surfaces, representing precipitation of DOC derived from litter. Earthworms mixed nearly all the leaf litter into mineral soil within one year, and after two years the label was most enriched in particulate organic matter held within soil aggregates produced by worms. After three years 15-20% of the added label was recovered in mineral SOM. In the labeling chambers over 75% of belowground C allocation (BCA) was used in root and rhizosphere respiration in the first year after labeling. We recovered only 3.8% of estimated BCA in SOM after 3 years; however, expressed as a proportion of fine root production plus rhizosphere C flux, this value is 15.4%, comparable to that for leaf litter in the presence of earthworms. In conclusion, both roots and leaf litter contribute significantly to the formation of stabilized mineral SOM in temperate deciduous forests, and this process is profoundly altered by the invasion of lumbricid earthworms.

  1. Monitoring biodegradation of diesel fuel in bioventing processes using in situ respiration rate.

    Science.gov (United States)

    Lee, T H; Byun, I G; Kim, Y O; Hwang, I S; Park, T J

    2006-01-01

    An in situ measuring system of respiration rate was applied for monitoring biodegradation of diesel fuel in a bioventing process for bioremediation of diesel contaminated soil. Two laboratory-scale soil columns were packed with 5 kg of soil that was artificially contaminated by diesel fuel as final TPH (total petroleum hydrocarbon) concentration of 8,000 mg/kg soil. Nutrient was added to make a relative concentration of C:N:P = 100:10:1. One soil column was operated with continuous venting mode, and the other one with intermittent (6 h venting/6 h rest) venting mode. On-line O2 and CO2 gas measuring system was applied to measure O2 utilisation and CO2 production during biodegradation of diesel for 5 months. Biodegradation rate of TPH was calculated from respiration rate measured by the on-line gas measuring system. There were no apparent differences between calculated biodegradation rates from two columns with different venting modes. The variation of biodegradation rates corresponded well with trend of the remaining TPH concentrations comparing other biodegradation indicators, such as C17/pristane and C18/phytane ratio, dehydrogenase activity, and the ratio of hydrocarbon utilising bacteria to total heterotrophic bacteria. These results suggested that the on-line measuring system of respiration rate would be applied to monitoring biodegradation rate and to determine the potential applicability of bioventing process for bioremediation of oil contaminated soil.

  2. Timing and duration of autumn leaf development in Sweden

    Science.gov (United States)

    Bolmgren, Kjell

    2014-05-01

    The growing season is changing in both ends and autumn phases seem to be responding in more diverse ways than spring events. Indeed, we know little about autumn leaf phenological strategies and how they are correlated with fitness components or ecosystem properties, and how they vary between species and over bioclimatic gradients. In this study more than 10 000 students were involved in observing autumn leaf development at 378 sites all over Sweden (55-68°N). They followed an image based observation protocol classifying autumn leaf development into five levels, from summer green (level 0) to 100% autumn leaf colored (level 4) canopy. In total, they submitted almost 12 000 observations between August 9 and November 15. 75% of the observations were made on the common species of Populus tremula, Betula pendula/pubescens and Sorbus aucuparia. The expected (negative) correlation between latitude and start of leaf senescence (level 2) was found in Populus and Betula, but not in Sorbus. The duration of the leaf senescence period, defined as the period between 1/3 (level 2) and 100% (level 4) of the canopy autumn leaf colored, was negatively correlated with latitude in Populus and Betula, but not in Sorbus. There was also a strong (negative) correlation of the start (level 2) and the duration of the leaf senescence in the early senescing Sorbus and Betula, while this effect was weaker in the late senescing Populus.

  3. Impaired photosynthesis and increased leaf construction costs may induce floral stress during episodes of global warming over macroevolutionary timescales.

    Science.gov (United States)

    Haworth, Matthew; Belcher, Claire M; Killi, Dilek; Dewhirst, Rebecca A; Materassi, Alessandro; Raschi, Antonio; Centritto, Mauro

    2018-04-18

    Global warming events have coincided with turnover of plant species at intervals in Earth history. As mean global temperatures rise, the number, frequency and duration of heat-waves will increase. Ginkgo biloba was grown under controlled climatic conditions at two different day/night temperature regimes (25/20 °C and 35/30 °C) to investigate the impact of heat stress. Photosynthetic CO 2 -uptake and electron transport were reduced at the higher temperature, while rates of respiration were greater; suggesting that the carbon balance of the leaves was adversely affected. Stomatal conductance and the potential for evaporative cooling of the leaves was reduced at the higher temperature. Furthermore, the capacity of the leaves to dissipate excess energy was also reduced at 35/30 °C, indicating that photo-protective mechanisms were no longer functioning effectively. Leaf economics were adversely affected by heat stress, exhibiting an increase in leaf mass per area and leaf construction costs. This may be consistent with the selective pressures experienced by fossil Ginkgoales during intervals of global warming such as the Triassic - Jurassic boundary or Early Eocene Climatic Optimum. The physiological and morphological responses of the G. biloba leaves were closely interrelated; these relationships may be used to infer the leaf economics and photosynthetic/stress physiology of fossil plants.

  4. Leaf area index from litter collection: impact of specific leaf area variability within a beech stand

    Energy Technology Data Exchange (ETDEWEB)

    Bouriaud, O. [Inst. National de la Recherche Agronomique, Centre de Recherches Forestieres de Nancy, Champenoux (France); Soudani, K. [Univ. Paris-Sud XI, Dept. d' Ecophysiologie Vegetale, Lab. Ecologie Systematique et Evolution, Orsay Cedex (France); Breda, N. [Inst. National de la Recherche Agronomique, Centre de Recherches Forestieres de Nancy, Champenoux (France)

    2003-06-01

    Litter fall collection is a direct method widely used to estimate leaf area index (LAI) in broad-leaved forest stands. Indirect measurements using radiation transmittance and gap fraction theory are often compared and calibrated against litter fall, which is considered as a reference method, but few studies address the question of litter specific leaf area (SLA) measurement and variability. SLA (leaf area per unit of dry weight, m{sup 2}{center_dot}g{sup -1}) is used to convert dry leaf litter biomass (g .m{sup -}2) into leaf area per ground unit area (m{sup 2}{center_dot}m{sup -2}). We paid special attention to this parameter in two young beech stands (dense and thinned) in northeastern France. The variability of both canopy (closure, LAI) and site conditions (soil properties, vegetation) was investigated as potential contributing factors to beech SLA variability. A systematic description of soil and floristic composition was performed and three types of soil were identified. Ellenberg's indicator values were averaged for each plot to assess nitrogen soil content. SLA of beech litter was measured three times during the fall in 23 plots in the stands (40 ha). Litter was collected bimonthly in square-shaped traps (0.5 m{sup 2}) and dried. Before drying, 30 leaves per plot and for each date were sampled, and leaf length, width, and area were measured with the help of a LI-COR areameter. SLA was calculated as the ratio of cumulated leaf area to total dry weight of the 30 leaves. Leaves characteristics per plot were averaged for the three dates of litter collection. Plant area index (PAI), estimated using the LAI-2000 plant canopy analyser and considering only the upper three rings, ranged from 2.9 to 8.1. Specific leaf area of beech litter was also highly different from one plot to the other, ranging from 150 to 320 cm{sup 2}{center_dot}g{sup -1}. Nevertheless, no relationship was found between SLA and stand canopy closure or PAI On the contrary, a significant

  5. Leaf area index from litter collection: impact of specific leaf area variability within a beech stand

    International Nuclear Information System (INIS)

    Bouriaud, O.; Soudani, K.; Breda, N.

    2003-01-01

    Litter fall collection is a direct method widely used to estimate leaf area index (LAI) in broad-leaved forest stands. Indirect measurements using radiation transmittance and gap fraction theory are often compared and calibrated against litter fall, which is considered as a reference method, but few studies address the question of litter specific leaf area (SLA) measurement and variability. SLA (leaf area per unit of dry weight, m 2 ·g -1 ) is used to convert dry leaf litter biomass (g .m - 2) into leaf area per ground unit area (m 2 ·m -2 ). We paid special attention to this parameter in two young beech stands (dense and thinned) in northeastern France. The variability of both canopy (closure, LAI) and site conditions (soil properties, vegetation) was investigated as potential contributing factors to beech SLA variability. A systematic description of soil and floristic composition was performed and three types of soil were identified. Ellenberg's indicator values were averaged for each plot to assess nitrogen soil content. SLA of beech litter was measured three times during the fall in 23 plots in the stands (40 ha). Litter was collected bimonthly in square-shaped traps (0.5 m 2 ) and dried. Before drying, 30 leaves per plot and for each date were sampled, and leaf length, width, and area were measured with the help of a LI-COR areameter. SLA was calculated as the ratio of cumulated leaf area to total dry weight of the 30 leaves. Leaves characteristics per plot were averaged for the three dates of litter collection. Plant area index (PAI), estimated using the LAI-2000 plant canopy analyser and considering only the upper three rings, ranged from 2.9 to 8.1. Specific leaf area of beech litter was also highly different from one plot to the other, ranging from 150 to 320 cm 2 ·g -1 . Nevertheless, no relationship was found between SLA and stand canopy closure or PAI On the contrary, a significant relationship between SLA and soil properties was observed. Both SLA

  6. Fourteen Annually Repeated Droughts Suppressed Autotrophic Soil Respiration and Resulted in an Ecosystem Change

    NARCIS (Netherlands)

    Kopittke, G.R.; Tietema, A.; van Loon, E.; Asscheman, D.

    2014-01-01

    Predictions of future climate over the next 100 years show that the frequency of long periods of droughts in summer will increase in the Netherlands. This study investigated the effect of 14 annually repeated droughts on soil respiration at a Dutch heathland. Field measurements of total soil

  7. Abnormal mitochondrial respiration in failed human myocardium.

    Science.gov (United States)

    Sharov, V G; Todor, A V; Silverman, N; Goldstein, S; Sabbah, H N

    2000-12-01

    Chronic heart failure (HF) is associated with morphologic abnormalities of cardiac mitochondria including hyperplasia, reduced organelle size and compromised structural integrity. In this study, we examined whether functional abnormalities of mitochondrial respiration are also present in myocardium of patients with advanced HF. Mitochondrial respiration was examined using a Clark electrode in an oxygraph cell containing saponin-skinned muscle bundles obtained from myocardium of failed explanted human hearts due to ischemic (ICM, n=9) or idiopathic dilated (IDC, n=9) cardiomyopathy. Myocardial specimens from five normal donor hearts served as controls (CON). Basal respiratory rate, respiratory rate after addition of the substrates glutamate and malate (V(SUB)), state 3 respiration (after addition of ADP, V(ADP)) and respiration after the addition of atractyloside (V(AT)) were measured in scar-free muscle bundles obtained from the subendocardial (ENDO) and subepicardial (EPI) thirds of the left ventricular (LV) free wall, interventricular septum and right ventricular (RV) free wall. There were no differences in basal and substrate-supported respiration between CON and HF regardless of etiology. V(ADP)was significantly depressed both in ICM and IDC compared to CON in all the regions studied. The respiratory control ratio, V(ADP)/V(AT), was also significantly decreased in HF compared to CON. In both ICM and IDC, V(ADP)was significantly lower in ENDO compared to EPI. The results indicate that mitochondrial respiration is abnormal in the failing human heart. The findings support the concept of low myocardial energy production in HF via oxidative phosphorylation, an abnormality with a potentially impact on global cardiac performance. Copyright 2000 Academic Press.

  8. A model using marginal efficiency of investment to analyse carbon and nitrogen interactions in terrestrial ecosystems (ACONITE Version 1)

    Science.gov (United States)

    Thomas, R. Q.; Williams, M.

    2014-04-01

    Carbon (C) and nitrogen (N) cycles are coupled in terrestrial ecosystems through multiple processes including photosynthesis, tissue allocation, respiration, N fixation, N uptake, and decomposition of litter and soil organic matter. Capturing the constraint of N on terrestrial C uptake and storage has been a focus of the Earth System modelling community. However there is little understanding of the trade-offs and sensitivities of allocating C and N to different tissues in order to optimize the productivity of plants. Here we describe a new, simple model of ecosystem C-N cycling and interactions (ACONITE), that builds on theory related to plant economics in order to predict key ecosystem properties (leaf area index, leaf C : N, N fixation, and plant C use efficiency) using emergent constraints provided by marginal returns on investment for C and/or N allocation. We simulated and evaluated steady-state ecosystem stocks and fluxes in three different forest ecosystems types (tropical evergreen, temperate deciduous, and temperate evergreen). Leaf C : N differed among the three ecosystem types (temperate deciduous database describing plant traits. Gross primary productivity (GPP) and net primary productivity (NPP) estimates compared well to observed fluxes at the simulation sites. Simulated N fixation at steady-state, calculated based on relative demand for N and the marginal return on C investment to acquire N, was an order of magnitude higher in the tropical forest than in the temperate forest, consistent with observations. A sensitivity analysis revealed that parameterization of the relationship between leaf N and leaf respiration had the largest influence on leaf area index and leaf C : N. Also, a widely used linear leaf N-respiration relationship did not yield a realistic leaf C : N, while a more recently reported non-linear relationship performed better. A parameter governing how photosynthesis scales with day length had the largest influence on total vegetation C

  9. Occurrence of trace elements in respirable coal dust

    International Nuclear Information System (INIS)

    Sahoo, B.N.

    1991-01-01

    Inhalation of fine particles of coal dust contributes significantly to the occurrence of the disease, pneumoconiosis, prevailing in coal mining community. It is not presently known whether only the coal dust or specific chemical compounds or synergistic effects of several compounds associated with respirable coal dust is responsible for the disease, pneumoconiosis. The present paper describes the quantitative determination of ten minor and trace elements in respirable coal dust particles by atomic absorption spectrophotometric methods. The respirable coal dust samples are collected at the mine atmosphere during drilling in coal scams by using Messrs. Casella's Hexlet apparatus specially designed and fitted with horizontal elutriator to collect the respirable coal dust fraction simulating as near as possible to the lung's retention of the coal miners. After destruction of organic matter by wet oxidation and filtering off clay and silica, Fe, Ca, Mg, Na, K, Mn, Cu, Zn, Cd, and Ni were determined directly in the resulting solution by atomic absorption spectrophotometric procedures. The results show that the trace metals are more acute in lower range of size spectrum. Correlation coefficient, enrichment factor and linear regression values and their inverse relationship between the slope and EF values suggest that, in general, the trace metals in respirable particulates are likely to be from coal derived source if their concentrations are likewise high in the coal. The trace metal analytical data of respirable particulates fitted well to the linear regressive equation. The results of the studies are of importance as it may throw some light on the respirable lung disease 'pneumoconiosis' which are predominant in coal mining community. (author). 13 refs., 6 tabs

  10. Partitioning of ecosystem respiration in a paludified shallow-peat spruce forest in the southern taiga of European Russia

    International Nuclear Information System (INIS)

    Kurbatova, J; Tatarinov, F; Varlagin, A; Avilov, V; Molchanov, A; Kozlov, D; Ivanov, D; Valentini, R

    2013-01-01

    Soil, tree stems, and ecosystem carbon dioxide fluxes were measured by chambers and eddy covariance methods in a paludified shallow-peat spruce forest in the southern taiga of European Russia (Tver region, 56° N 33° E) during the growing seasons of 2002–2012. The site was established in 1998 as part of the EUROSIBERIAN CARBONFLUX project, an international field experiment examining atmosphere–biosphere interaction in Siberia and European Russia. In all years the observed annual cumulative net ecosystem flux was positive (the forest was a source of carbon to the atmosphere). Soil and tree stem respiration was a significant part of the total ecosystem respiration (ER) in this paludified shallow-peat spruce forest. On average, 49% of the ER came from soil respiration. We found that the soil fluxes exhibited high seasonal variability, ranging from 0.7 to 10 μmol m −2  s −1 . Generally, the soil respiration depended on the soil temperature and ground water level. In drought conditions, the soil respiration was low and did not depend on temperature. The stem respiration of spruces grew intensively in May, had permanently high values from June to the end of September, and in October it dramatically decreased. The tree stem respiration in midsummer was about 3–5 μmol m −2  s −1 for dominant trees and about 1–2 μmol m −2  s −1 for subdominant trees. The respiration of living tree stems was about 10–20% of the ER. (letter)

  11. Phytochemical Analysis, Antifungal and Antioxidant Activity of Leaf ...

    African Journals Online (AJOL)

    Science, Technology and Arts Research Journal ... of total phenolics, antifungal and antioxidant activity of leaf and fruit extract of Zizyphus xylopyrus (Retz.) ... Flavonoids, saponins, terpenoids, tannins and phenols were found in both extracts.

  12. Effects of simulated warming on soil respiration to XiaoPo lake

    Science.gov (United States)

    Zhao, Shuangkai; Chen, Kelong; Wu, Chengyong; Mao, Yahui

    2018-02-01

    The main flux of carbon cycling in terrestrial and atmospheric ecosystems is soil respiration, and soil respiration is one of the main ways of soil carbon output. This is of great significance to explore the dynamic changes of soil respiration rate and its effect on temperature rise, and the correlation between environmental factors and soil respiration. In this study, we used the open soil carbon flux measurement system (LI-8100, LI-COR, NE) in the experimental area of the XiaoPo Lake wetland in the Qinghai Lake Basin, and the Kobresia (Rs) were measured, and the soil respiration was simulated by simulated temperature (OTC) and natural state. The results showed that the temperature of 5 cm soil was 1.37 °C higher than that of the control during the experiment, and the effect of warming was obvious. The respiration rate of soil under warming and natural conditions showed obvious diurnal variation and monthly variation. The effect of warming on soil respiration rate was promoted and the effect of precipitation on soil respiration rate was inhibited. Further studies have shown that the relationship between soil respiration and 5 cm soil temperature under the control and warming treatments can be described by the exponential equation, and the correlation analysis between the two plots shows a very significant exponential relationship (p main influencing factor of soil respiration in this region.

  13. Root Zone Respiration on Hydroponically Grown Wheat Plant Systems

    Science.gov (United States)

    Soler-Crespo, R. A.; Monje, O. A.

    2010-01-01

    Root respiration is a biological phenomenon that controls plant growth and physiological development during a plant's lifespan. This process is dependent on the availability of oxygen in the system where the plant is located. In hydroponic systems, where plants are submerged in a solution containing vital nutrients but no type of soil, the availability of oxygen arises from the dissolved oxygen concentration in the solution. This oxygen concentration is dependent on the , gas-liquid interface formed on the upper surface of the liquid, as given by Henry's Law, depending on pressure and temperature conditions. Respiration rates of the plants rise as biomass and root zone increase with age. The respiration rate of Apogee wheat plants (Triticum aestivum) was measured as a function of light intensity (catalytic for photosynthesis) and CO2 concentration to determine their effect on respiration rates. To determine their effects on respiration rate and plant growth microbial communities were introduced into the system, by Innoculum. Surfactants were introduced, simulating gray-water usage in space, as another factor to determine their effect on chemical oxygen demand of microbials and on respiration rates of the plants. It is expected to see small effects from changes in CO2 concentration or light levels, and to see root respiration decrease in an exponential manner with plant age and microbial activity.

  14. Use of respirators for protection of workers against airborne radioactive materials

    International Nuclear Information System (INIS)

    Revoir, W.H.

    1990-01-01

    The various types of respirators and the requirements for an effective respirator program are outlined. The use of specific types of respirators to protect workers against inhalation of airborne radioactive materials is discussed. Problems encountered in using respirators in the nuclear industry which have resulted in worker injury and death are described

  15. Linear relations between leaf mass per area (LMA) and seasonal climate discovered through Linear Manifold Clustering (LMC)

    Science.gov (United States)

    Kiang, N. Y.; Haralick, R. M.; Diky, A.; Kattge, J.; Su, X.

    2016-12-01

    Leaf mass per area (LMA) is a critical variable in plant carbon allocation, correlates with leaf activity traits (photosynthetic activity, respiration), and is a controller of litterfall mass and hence carbon substrate for soil biogeochemistry. Recent advances in understanding the leaf economics spectrum (LES) show that LMA has a strong correlation with leaf life span, a trait that reflects ecological strategy, whereas physiological traits that control leaf activity scale with each other when mass-normalized (Osnas et al., 2013). These functional relations help reduce the number of independent variables in quantifying leaf traits. However, LMA is an independent variable that remains a challenge to specify in dynamic global vegetation models (DGVMs), when vegetation types are classified into a limited number of plant functional types (PFTs) without clear mechanistic drivers for LMA. LMA can range orders of magnitude across plant species, as well as vary within a single plant, both vertically and seasonally. As climate relations in combination with alternative ecological strategies have yet to be well identified for LMA, we have assembled 22,000 records of LMA spanning 0.004 - 33 mg/m2 from the numerous contributors to the TRY database (Kattge et al., 2011), with observations distributed over several climate zones and plant functional categories (growth form, leaf type, phenology). We present linear relations between LMA and climate variables, including seasonal temperature, precipitation, and radiation, as derived through Linear Manifold Clustering (LMC). LMC is a stochastic search technique for identifying linear dependencies between variables in high dimensional space. We identify a set of parsimonious classes of LMA-climate groups based on a metric of minimum description to identify structure in the data set, akin to data compression. The relations in each group are compared to Köppen-Geiger climate classes, with some groups revealing continuous linear relations

  16. Comparative Study on the Antioxidant Activity of Leaf Extract and Carotenoids Extract from Ipomoea batatas var. Oren (Sweetpotato) Leaves

    OpenAIRE

    Seow-Mun Hue; Amru Nasrulhaq Boyce; Chandran Somasundram

    2011-01-01

    Ipomoea batatas (Sweetpotato) is currently ranked sixth in the total world food production and are planted mainly for their storage roots. The present study was undertaken to evaluate and compare the antioxidant properties of the leaf and carotenoids extract from the Ipomoea batatas var. Oren leaves. Total flavonoids in the leaf extract was 144.6 ± 40.5 μg/g compared to 114.86 ± 4.35 μg/g catechin equivalent in the carotenoids extract. Total polyphenols in the leaf extrac...

  17. Organic fuels for respiration in tropical river systems

    Science.gov (United States)

    Ward, N.; Keil, R. G.; Richey, J. E.; Krusche, A. V.; Medeiros, P. M.

    2011-12-01

    Watershed-derived organic matter is thought to provide anywhere from 30-90% of the organic matter in rivers (e.g. Hernes et al 2008; Spencer et al 2010). The most abundant biochemicals on land are cellulose, hemicelluloses, and lignin. Combined, they represent as much as 80% of the biomass in a typical forest and as much as 60% of the biomass in a typical field (natural or crop)(Bose et al 2009; Bridgeman et al., 2007; Hu and Zu 2006; Martens et al 2004). They are often assumed to be refractory and hard to degrade, but this assumption is at odds with virtually all observations: soils and marine sediments are not accumulating vast amounts of these compounds (Hedges and Oades, 1997), and degradation experiments suggest that cellulose, hemicelluloses and lignin are reactive and likely to be important fuels for respiration (Benner, 1991; Haddad et al, 1992; Dittmar et al, 2001; Otto and Simpson, 2006). During several trips to the lower Amazon River, incubation experiments were performed in which the biological degradation of lignin phenols was observed in order to assess the contribution of microbial respiration of terrestrially-derived macromolecules to gross respiration and CO2 gas evasion rates. Both particulate and dissolved lignin concentrations decreased by ~40% after being incubated in the dark for 5-7 days, indicating a turnover time of the entire lignin pool of 12-18 days. These results shift the paradigm that lignocellulose derived OM is highly recalcitrant, and indicate that microbial respiration of lignocellulose may play a larger role in total respiration rates/CO2 outgassing than previously thought. A simple mass balance calculation was done to test whether microbial degradation alone could explain the lignin data observed in the field. First, a theoretical particulate lignin concentration for Macapa was calculated based on the observed data at Obidos. The measured rate of particulate lignin degradation was multiplied by the transit time of water from

  18. The drought of 2012: Effects on photosynthesis and soil respiration in bioenergy cropping systems of the Midwest USA

    Science.gov (United States)

    Cruse, M.; Kucharik, C. J.

    2012-12-01

    Climate change is predicted to increase the frequency and severity of drought conditions across the central US. This heightened risk on producers and economies alike also supports the need to improve our understanding of how extreme environmental conditions impact other ecosystem services such as carbon sequestration, which is directly linked to net ecosystem exchange (NEE). In doing so, the scientific community aims to improve the realism of ecosystem models that are relied upon to project changes in large scale and long-term land surface-atmosphere carbon exchange as they are affected by continued land management change and climate change. One such large-scale land management change of the next several decades in the Midwest US could be the expansion of bioenergy cropping systems across the landscape. A wide range of bioenergy cropping systems (e.g., miscanthus, switchgrass, diverse prairie, hybrid poplar) are now targeted to support a feedstock supply chain for production of cellulosic biofuels. Many of these agroecosystems have only recently begun to appear as functional types in dynamic ecosystem models, and a general lack of observational data across a wide range of soils and climate has hampered model development and validation. In response to this shortcoming, from 2009 through 2012, component measurements of ecosystem carbon exchange (total soil respiration and leaf level photosynthetic rates) have been made along with measurements of other soil and meteorological variables in three model bioenergy cropping systems (continuous corn, hybrid poplar and switchgrass) at the Great Lakes Bioenergy Research Center (GLBRC) field trial at Arlington, Wisconsin. The three cropping systems encompass a wide range of growth (e.g. C3 vs. C4, annual vs. perennial) and management (e.g., tillage, harvesting) strategies that are predicted to impart different controls on NEE given likely varying biological responses to extreme weather events. Throughout the study period, the

  19. Transcriptional regulation of respiration in yeast metabolizing differently repressive carbon substrates

    Directory of Open Access Journals (Sweden)

    Fendt Sarah-Maria

    2010-02-01

    Full Text Available Abstract Background Depending on the carbon source, Saccharomyces cerevisiae displays various degrees of respiration. These range from complete respiration as in the case of ethanol, to almost complete fermentation, and thus very low degrees of respiration on glucose. While many key regulators are known for these extreme cases, we focus here on regulators that are relevant at intermediate levels of respiration. Results We address this question by linking the functional degree of respiration to transcriptional regulation via enzyme abundances. Specifically, we investigated aerobic batch cultures with the differently repressive carbon sources glucose, mannose, galactose and pyruvate. Based on 13C flux analysis, we found that the respiratory contribution to cellular energy production was largely absent on glucose and mannose, intermediate on galactose and highest on pyruvate. In vivo abundances of 40 respiratory enzymes were quantified by GFP-fusions under each condition. During growth on the partly and fully respired substrates galactose and pyruvate, several TCA cycle and respiratory chain enzymes were significantly up-regulated. From these enzyme levels and the known regulatory network structure, we determined the probability for a given transcription factor to cause the coordinated expression changes. The most probable transcription factors to regulate the different degrees of respiration were Gcr1p, Cat8p, the Rtg-proteins and the Hap-complex. For the latter three ones we confirmed their importance for respiration by quantifying the degree of respiration and biomass yields in the corresponding deletion strains. Conclusions Cat8p is required for wild-type like respiration, independent of its known activation of gluconeogenic genes. The Rtg-proteins and the Hap-complex are essential for wild-type like respiration under partially respiratory conditions. Under fully respiratory conditions, the Hap-complex, but not the Rtg-proteins are essential

  20. Transcriptional regulation of respiration in yeast metabolizing differently repressive carbon substrates.

    Science.gov (United States)

    Fendt, Sarah-Maria; Sauer, Uwe

    2010-02-18

    Depending on the carbon source, Saccharomyces cerevisiae displays various degrees of respiration. These range from complete respiration as in the case of ethanol, to almost complete fermentation, and thus very low degrees of respiration on glucose. While many key regulators are known for these extreme cases, we focus here on regulators that are relevant at intermediate levels of respiration. We address this question by linking the functional degree of respiration to transcriptional regulation via enzyme abundances. Specifically, we investigated aerobic batch cultures with the differently repressive carbon sources glucose, mannose, galactose and pyruvate. Based on 13C flux analysis, we found that the respiratory contribution to cellular energy production was largely absent on glucose and mannose, intermediate on galactose and highest on pyruvate. In vivo abundances of 40 respiratory enzymes were quantified by GFP-fusions under each condition. During growth on the partly and fully respired substrates galactose and pyruvate, several TCA cycle and respiratory chain enzymes were significantly up-regulated. From these enzyme levels and the known regulatory network structure, we determined the probability for a given transcription factor to cause the coordinated expression changes. The most probable transcription factors to regulate the different degrees of respiration were Gcr1p, Cat8p, the Rtg-proteins and the Hap-complex. For the latter three ones we confirmed their importance for respiration by quantifying the degree of respiration and biomass yields in the corresponding deletion strains. Cat8p is required for wild-type like respiration, independent of its known activation of gluconeogenic genes. The Rtg-proteins and the Hap-complex are essential for wild-type like respiration under partially respiratory conditions. Under fully respiratory conditions, the Hap-complex, but not the Rtg-proteins are essential for respiration.

  1. Why do leaf-tying caterpillars abandon their leaf ties?

    Directory of Open Access Journals (Sweden)

    Michelle Sliwinski

    2013-09-01

    Full Text Available Leaf-tying caterpillars act as ecosystem engineers by building shelters between overlapping leaves, which are inhabited by other arthropods. Leaf-tiers have been observed to leave their ties and create new shelters (and thus additional microhabitats, but the ecological factors affecting shelter fidelity are poorly known. For this study, we explored the effects of resource limitation and occupant density on shelter fidelity and assessed the consequences of shelter abandonment. We first quantified the area of leaf material required for a caterpillar to fully develop for two of the most common leaf-tiers that feed on white oak, Quercus alba. On average, Psilocorsis spp. caterpillars consumed 21.65 ± 0.67 cm2 leaf material to complete development. We also measured the area of natural leaf ties found in a Maryland forest, to determine the distribution of resources available to caterpillars in situ. Of 158 natural leaf ties examined, 47% were too small to sustain an average Psilocorsis spp. caterpillar for the entirety of its development. We also manipulated caterpillar densities within experimental ties on potted trees to determine the effects of cohabitants on the likelihood of a caterpillar to leave its tie. We placed 1, 2, or 4 caterpillars in ties of a standard size and monitored the caterpillars twice daily to track their movement. In ties with more than one occupant, caterpillars showed a significantly greater propensity to leave their tie, and left sooner and at a faster rate than those in ties as single occupants. To understand the consequences of leaf tie abandonment, we observed caterpillars searching a tree for a site to build a shelter in the field. This is a risky behavior, as 17% of the caterpillars observed died while searching for a shelter site. Caterpillars that successfully built a shelter traveled 110 ± 20 cm and took 28 ± 7 min to find a suitable site to build a shelter. In conclusion, leaf-tying caterpillars must frequently

  2. No diurnal variation in rate or carbon isotope composition of soil respiration in a boreal forest

    International Nuclear Information System (INIS)

    Betson, N.R.; Gottlicher, S.G.; Hogberg, P.; Hall, M.; Wallin, G.; Richter, A.

    2007-01-01

    This study evaluated the diurnal variability in the rate and stable carbon isotope ratio ((delta) 13 C) of soil respiration in a northern boreal forest, measured with opaque chambers after the removal of understory vegetation. The experiment was conducted in June and August 2004 at the Picea abies L. Karst-dominated Flakaliden Research Forest in northern Sweden, using unfertilized girdled-tree plots and unfertilized non-girdled tree plots. Soil respiration and (delta) 13 C of soil-respired carbon dioxide (CO 2 ) were measured every 4 hours on 6 plots, with a total of 11 sampling times over each 48 hour period. The purpose was to clarify an earlier study regarding the origin of diurnal patterns of soil CO 2 flux. This study explored whether the diurnal patterns were the result of photosynthetic CO 2 uptake during the day by the understory or whether there were underlying trends in soil respiration driven by plant root allocation. The sampling campaigns undertaken in this study investigated whether diurnal variations in soil respiration rate and (delta) 13 C exist in this ecosystem when no understory vegetation is present. Shoot photosynthesis and environmental parameters were measured simultaneously. Despite significant variations in climatic conditions and shoot photosynthetic rates in non-girdled trees, no diurnal patterns in soil respiration rates and (delta) 13 C were noted in either treatment. The lack of detectable diurnal changes in both treatments indicates that modeling of daily boreal forest carbon balances based on single instantaneous measurements are unlikely to be misconstrued by substantial diurnal trends. However, it was suggested that spatial variable should be accounted for, given the large standard errors. The impact of tree girdling on soil respiration rates also emphasized the significance of canopy photosynthesis in driving soil processes. 37 refs., 2 figs

  3. Climatic Controls on Leaf Nitrogen Content and Implications for Biochemical Modeling.

    Science.gov (United States)

    Tcherednichenko, I. A.; White, M.; Bastidas, L.

    2007-12-01

    Leaf nitrogen (N) content, expressed as percent total nitrogen per unit of leaf dry mass, is a widely used parameter in biochemical modeling, due mainly to its role as a potentially limiting factor for photosynthesis. The amount of nitrogen, however, does not occur in a fixed amount in every leaf, but rather varies continuously with the leaf life cycle, in constant response to soil-root-stem-leaf-climate interactions and demand for growth. Moreover, while broad data on leaf N has become available it is normally measured under ambient conditions with consequent difficulty for distinguishing between genetic and time specific environmental effects. In the present work we: 1) Investigate the theoretical variation of leaf mass, specific heat capacity and leaf thickness of full sun-expanded leaves as a regulatory mechanism to ensure thermal survival along with long-term climatic radiation/temperature gradient; and discuss nitrogen and carbon controls on leaf thickness. 2) Based on possible states of partition between nitrogenous and non-nitrogenous components of a leaf we further derive probability density functions (PDFs) of nitrogen and carbon content and assess the effect of water and nutrient uptake on the PDFs. 3) Translate the results to spatially explicit representation over the conterminous USA at 1 km spatial resolution by providing maximum potential values of leaf N of fully expanded leaf optimally suited for long term climatic averages values and soils conditions. Implications for potential presence of inherently slow/fast growing species are discussed along with suitability of results for use by biochemical models.

  4. Elemental Concentration of Inhalable and Respirable Particulate ...

    African Journals Online (AJOL)

    20537 and respirable foam for I.O.M sampler. The elemental composition (Co, Ni, Zn, Cu, Fe, Pb, Cr, Mn and Cd) were analyzed by using Atomic Absorption Spectrophotometric (AAS). The data generated were subjected to descriptive analysis. In inhalable fraction,the enrichment factor ranged from 1-73.3 while in respirable ...

  5. Metabolic interactions between methanogenic consortia and anaerobic respiring bacteria

    DEFF Research Database (Denmark)

    Stams, A.J.; Oude Elferink, S.J.; Westermann, Peter

    2003-01-01

    Most types of anaerobic respiration are able to outcompete methanogenic consortia for common substrates if the respective electron acceptors are present in sufficient amounts. Furthermore, several products or intermediate compounds formed by anaerobic respiring bacteria are toxic to methanogenic...... consortia. Despite the potentially adverse effects, only few inorganic electron acceptors potentially utilizable for anaerobic respiration have been investigated with respect to negative interactions in anaerobic digesters. In this chapter we review competitive and inhibitory interactions between anaerobic...... respiring populations and methanogenic consortia in bioreactors. Due to the few studies in anaerobic digesters, many of our discussions are based upon studies of defined cultures or natural ecosystems...

  6. Reductions in the variations of respiration signals for respiratory-gated radiotherapy when using the video-coaching respiration guiding system

    Science.gov (United States)

    Lee, Hyun Jeong; Yea, Ji Woon; Oh, Se An

    2015-07-01

    Respiratory-gated radiation therapy (RGRT) has been used to minimize the dose to normal tissue in lung-cancer radiotherapy. The present research aims to improve the regularity of respiration in RGRT by using a video-coached respiration guiding system. In the study, 16 patients with lung cancer were evaluated. The respiration signals of the patients were measured by using a realtime position management (RPM) respiratory gating system (Varian, USA), and the patients were trained using the video-coaching respiration guiding system. The patients performed free breathing and guided breathing, and the respiratory cycles were acquired for ~5 min. Then, Microsoft Excel 2010 software was used to calculate the mean and the standard deviation for each phase. The standard deviation was computed in order to analyze the improvement in the respiratory regularity with respect to the period and the displacement. The standard deviation of the guided breathing decreased to 48.8% in the inhale peak and 24.2% in the exhale peak compared with the values for the free breathing of patient 6. The standard deviation of the respiratory cycle was found to be decreased when using the respiratory guiding system. The respiratory regularity was significantly improved when using the video-coaching respiration guiding system. Therefore, the system is useful for improving the accuracy and the efficiency of RGRT.

  7. Development of an Advanced Respirator Fit Test Headform (Postprint)

    Science.gov (United States)

    2012-11-01

    N95 filtering facepiece respirators (FFRs) for pro - tection studies against viable airborne particles. A Static (i.e., non-moving, non-speaking...requiredto wear respirators to reduce their exposure to air- borne hazards.(1) The U.S. Occupational Safety and Health Administration ( OSHA ) Respiratory...13 workplace protection factors.(9,10). Inward leakage (IL) of con - taminants into a respirator facepiece has been described as a combination of

  8. An isotope approach based on C-13 pulse-chase labelling vs. the root trenching method to separate heterotrophic and autotrophic respiration in cultivated peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Biasi, C.; Pitkamaki, A. S.; Tavi, N. M.; Koponen, H. T.; Martikainen, P. J. [Univ.of Eastern Finland, Kuopio (Finland). Dept. of Environmental Science], e-mail: christina.biasi@uef.fi

    2012-11-01

    We tested an isotope method based on C-13 pulse-chase labelling for determining the fractional contribution of soil microbial respiration to overall soil respiration in an organic soil (cutaway peatland, eastern Finland), cultivated with the bioenergy crop, reed canary grass. The plants were exposed to CO{sub 2}-13 for five hours and the label was thereafter determined in CO{sub 2} derived from the soil-root system. A two-pool isotope mixing model was used to separate sources of respiration. The isotopic approach showed that a minimum of 50% of the total CO{sub 2} originated from soil-microbial respiration. Even though the method uses undisturbed soil-plant systems, it has limitations concerning the experimental determination of the true isotopic signal of all components contributing to autotrophic respiration. A trenching experiment which was comparatively conducted resulted in a 71% fractional contribution of soil-microbial respiration. This value was likely overestimated. Further studies are needed to evaluate critically the output from these two partitioning approaches. (orig.)

  9. Does oolong tea (Camellia sinensis) made from a combination of leaf and stem smell more aromatic than leaf-only tea? Contribution of the stem to oolong tea aroma.

    Science.gov (United States)

    Zeng, Lanting; Zhou, Ying; Fu, Xiumin; Mei, Xin; Cheng, Sihua; Gui, Jiadong; Dong, Fang; Tang, Jinchi; Ma, Shengzhou; Yang, Ziyin

    2017-12-15

    The raw materials used to make oolong tea (Camellia sinensis) are a combination of leaf and stem. Oolong tea made from leaf and stem is thought to have a more aromatic smell than leaf-only tea. However, there is no available evidence to support the viewpoint. In this study, sensory evaluation and detailed characterization of emitted and internal volatiles (not readily emitted, but stored in samples) of dry oolong teas and infusions indicated that the presence of stem did not significantly improve the total aroma characteristics. During the enzyme-active processes, volatile monoterpenes and theanine were accumulated more abundantly in stem than in leaf, while jasmine lactone, indole, and trans-nerolidol were lower in stem than in leaf. Tissue-specific aroma-related gene expression and availability of precursors of aroma compounds resulted in different aroma distributions in leaf and stem. This study presents the first determination of the contribution of stem to oolong tea aroma. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Dynamic characteristics of soil respiration in Yellow River Delta wetlands, China

    Science.gov (United States)

    Wang, Xiao; Luo, Xianxiang; Jia, Hongli; Zheng, Hao

    2018-02-01

    The stable soil carbon (C) pool in coastal wetlands, referred to as "blue C", which has been extensively damaged by climate change and soil degradation, is of importance to maintain global C cycle. Therefore, to investigate the dynamic characteristics of soil respiration rate and evaluate C budgets in coastal wetlands are urgently. In this study, the diurnal and seasonal variation of soil respiration rate in the reed wetland land (RL) and the bare wetland land (BL) was measured in situ with the dynamic gas-infrared CO2 method in four seasons, and the factors impacted on the dynamic characteristics of soil respiration were investigated. The results showed that the diurnal variation of soil respiration rate consistently presented a "U" curve pattern in April, July, and September, with the maximum values at 12:00 a.m. and the minimum values at 6:00 a.m. In the same season, the diurnal soil respiration rate in RL was significantly greater than those in BL (P respiration rate was 0.14, 0.42, and 0.39 μmol m-2 s-1 in RL, 0.05, 0.22, 0.13, and 0.01 μmol m-2 s-1 in BL, respectively. Soil surface temperature was the primary factor that influenced soil respiration, which was confirmed by the exponential positive correlation between the soil respiration rate and soil surface temperature in BL and RL (P respiration, confirming by the significantly negative correlation between soil respiration rate and the content of soluble salt. These results will be useful for understanding the mechanisms underlying soil respiration and elevating C sequestration potential in the coastal wetlands.

  11. Effect of litter, leaf cover and cover of basal internodes of the dominant species Molinia caerulea on seedling recruitment and established vegetation

    Science.gov (United States)

    Janeček, Štěpán; Lepš, Jan

    2005-09-01

    The effects of litter removal, leaf cover of established plants and cover of basal internodes of a dominant species Molinia caerulea on seedling germination and the dynamics of established plants were studied in a field experiment in an oligotrophic wet meadow. Although the negative influence of litter on total seedling number and seedling species composition was non-significant, litter significantly affected the dynamics of the established vegetation and caused inhibition of total leaf cover development. The effects of total leaf cover of established plants on seedling establishment changed during the vegetation season. Whereas the effect of total leaf cover was positive at the start and in the middle of the vegetation season, at the end the total leaf cover negatively affected seedling establishment. Both total leaf cover and cover of basal internodes affected seedling composition. Effects of these two variables were statistically separable suggesting that they are based on different mechanisms. The response of seedling establishment to these factors was species specific and, consequently, our data support the hypothesis that that biotically generated spatial heterogeneity can promote species co-existence through the differentiation of species regeneration niches.

  12. Hydrologic control of the oxygen isotope ratio of ecosystem respiration in a semi-arid woodland

    Directory of Open Access Journals (Sweden)

    J. H. Shim

    2013-07-01

    Full Text Available We conducted high frequency measurements of the δ18O value of atmospheric CO2 from a juniper (Juniperus monosperma woodland in New Mexico, USA, over a four-year period to investigate climatic and physiological regulation of the δ18O value of ecosystem respiration (δR. Rain pulses reset δR with the dominant water source isotope composition, followed by progressive enrichment of δR. Transpiration (ET was significantly related to post-pulse δR enrichment because the leaf water δ18O value showed strong enrichment with increasing vapor pressure deficit that occurs following rain. Post-pulse δR enrichment was correlated with both ET and the ratio of ET to soil evaporation (ET/ES. In contrast, the soil water δ18O value was relatively stable and δR enrichment was not correlated with ES. Model simulations captured the large post-pulse δR enrichments only when the offset between xylem and leaf water δ18O value was modeled explicitly and when a gross flux model for CO2 retro-diffusion was included. Drought impacts δR through the balance between evaporative demand, which enriches δR, and low soil moisture availability, which attenuates δR enrichment through reduced ET. The net result, observed throughout all four years of our study, was a negative correlation of post-precipitation δR enrichment with increasing drought.

  13. A comparison of step-and-shoot leaf sequencing algorithms that eliminate tongue-and-groove effects

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, Srijit [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States); Sahni, Sartaj [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States); Ranka, Sanjay [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States); Li, Jonathan [Department of Radiation Oncology, University of Florida, Gainesville, FL (United States); Palta, Jatinder [Department of Radiation Oncology, University of Florida, Gainesville, FL (United States)

    2004-07-21

    The performances of three recently published leaf sequencing algorithms for step-and-shoot intensity-modulated radiation therapy delivery that eliminates tongue-and-groove underdosage are evaluated. Proofs are given to show that the algorithm of Que et al (2004 Phys. Med. Biol. 49 399-405) generates leaf sequences free of tongue-and-groove underdosage and interdigitation. However, the total beam-on times could be up to n times those of the sequences generated by the algorithms of Kamath et al (2004 Phys. Med. Biol. 49 N7-N19), which are optimal in beam-on time for unidirectional leaf movement under the same constraints, where n is the total number of involved leaf pairs. Using 19 clinical fluence matrices and 100 000 randomly generated 15 x 15 matrices, the average monitor units and number of segments of the leaf sequences generated using the algorithm of Que et al are about two to four times those generated by the algorithm of Kamath et al.

  14. A comparison of step-and-shoot leaf sequencing algorithms that eliminate tongue-and-groove effects

    International Nuclear Information System (INIS)

    Kamath, Srijit; Sahni, Sartaj; Ranka, Sanjay; Li, Jonathan; Palta, Jatinder

    2004-01-01

    The performances of three recently published leaf sequencing algorithms for step-and-shoot intensity-modulated radiation therapy delivery that eliminates tongue-and-groove underdosage are evaluated. Proofs are given to show that the algorithm of Que et al (2004 Phys. Med. Biol. 49 399-405) generates leaf sequences free of tongue-and-groove underdosage and interdigitation. However, the total beam-on times could be up to n times those of the sequences generated by the algorithms of Kamath et al (2004 Phys. Med. Biol. 49 N7-N19), which are optimal in beam-on time for unidirectional leaf movement under the same constraints, where n is the total number of involved leaf pairs. Using 19 clinical fluence matrices and 100 000 randomly generated 15 x 15 matrices, the average monitor units and number of segments of the leaf sequences generated using the algorithm of Que et al are about two to four times those generated by the algorithm of Kamath et al

  15. Respirator studies for the Nuclear Regulatory Commission (NRC)

    International Nuclear Information System (INIS)

    Skaggs, B.J.; Fairchild, C.I.; DeField, J.D.; Hack, A.L.

    1985-01-01

    A project of the Health, Safety and Environment Division is described. The project provides the NRC with information of respiratory protective devices and programs for their licensee personnel. The following activities were performed during FY 1983: selection of alternate test aerosols for quality assurance testing of high-efficiency particulate air respirator filters; evaluation of MAG-1 spectacles for use with positive and negative-pressure respirators; development of a Manual of Respiratory Protection in Emergencies Involving Airborne Radioactive Materials, and technical assistance to NRC licensees regarding respirator applications. 2 references, 1 figure

  16. A pilot study of the nocturnal respiration rates in COPD patients in the home environment using a non-contact biomotion sensor

    International Nuclear Information System (INIS)

    Ballal, Tarig; Zaffaroni, Alberto; Heneghan, Conor; Shouldice, Redmond; Boyle, Patricia; McNicholas, Walter T; De Chazal, Philip; Donnelly, Seamas C

    2014-01-01

    Nocturnal respiration rate parameters were collected from 20 COPD subjects over an 8 week period, to determine if changes in respiration rate were associated with exacerbations of COPD. These subjects were primarily GOLD Class 2 to 4, and had been recently discharged from hospital following a recent exacerbation. The respiration rates were collected using a non-contact radio-frequency biomotion sensor which senses respiratory effort and body movement using a short-range radio-frequency sensor. An adaptive notch filter was applied to the measured signal to determine respiratory rate over rolling 15 s segments. The accuracy of the algorithm was initially verified using ten manually-scored 15 min segments of respiration extracted from overnight polysomnograms. The calculated respiration rates were within 1 breath min −1 for >98% of the estimates. For the 20 subjects monitored, 11 experienced one or more subsequent exacerbation of COPD (ECOPD) events during the 8 week monitoring period (19 events total). Analysis of the data revealed a significant increase in nocturnal respiration rate (e.g. >2 breath min −1 ) prior to many ECOPD events. Using a simple classifier of a change of 1 breath min −1 in the mode of the nocturnal respiration rate, a predictive rule showed a sensitivity of 63% and specificity of 85% for predicting an exacerbation within a 5 d window. We conclude that it is possible to collect respiration rates reliably in the home environment, and that the respiration rate may be a potential indicator of change in clinical status. (paper)

  17. Cattle respiration facility

    DEFF Research Database (Denmark)

    Hellwing, Anne Louise Frydendahl; Lund, Peter; Weisbjerg, Martin Riis

    2012-01-01

    In Denmark, the emission rate of methane from dairy cows has been calculated using the IPCC standard values for dairy cows in Western countries, due to the lack of national data. Therefore, four respiration chambers for dairy cows were built with the main purpose of measuring methane, but also...

  18. Estimating leaf photosynthetic pigments information by stepwise multiple linear regression analysis and a leaf optical model

    Science.gov (United States)

    Liu, Pudong; Shi, Runhe; Wang, Hong; Bai, Kaixu; Gao, Wei

    2014-10-01

    Leaf pigments are key elements for plant photosynthesis and growth. Traditional manual sampling of these pigments is labor-intensive and costly, which also has the difficulty in capturing their temporal and spatial characteristics. The aim of this work is to estimate photosynthetic pigments at large scale by remote sensing. For this purpose, inverse model were proposed with the aid of stepwise multiple linear regression (SMLR) analysis. Furthermore, a leaf radiative transfer model (i.e. PROSPECT model) was employed to simulate the leaf reflectance where wavelength varies from 400 to 780 nm at 1 nm interval, and then these values were treated as the data from remote sensing observations. Meanwhile, simulated chlorophyll concentration (Cab), carotenoid concentration (Car) and their ratio (Cab/Car) were taken as target to build the regression model respectively. In this study, a total of 4000 samples were simulated via PROSPECT with different Cab, Car and leaf mesophyll structures as 70% of these samples were applied for training while the last 30% for model validation. Reflectance (r) and its mathematic transformations (1/r and log (1/r)) were all employed to build regression model respectively. Results showed fair agreements between pigments and simulated reflectance with all adjusted coefficients of determination (R2) larger than 0.8 as 6 wavebands were selected to build the SMLR model. The largest value of R2 for Cab, Car and Cab/Car are 0.8845, 0.876 and 0.8765, respectively. Meanwhile, mathematic transformations of reflectance showed little influence on regression accuracy. We concluded that it was feasible to estimate the chlorophyll and carotenoids and their ratio based on statistical model with leaf reflectance data.

  19. The relationship between leaf water status, gas exchange, and spectral reflectance in cotton leaves

    Science.gov (United States)

    Bowman, William D.

    1989-01-01

    Measurements of leaf spectral reflectance, the components of water potential, and leaf gas exchanges as a function of leaf water content were made to evaluate the use of NIR reflectance as an indicator of plant water status. Significant correlations were determined between spectral reflectance at 810 nm, 1665 nm, and 2210 nm and leaf relative water content, total water potential, and turgor pressure. However, the slopes of these relationships were relatively shallow and, when evaluated over the range of leaf water contents in which physiological activity occurs (e.g., photosynthesis), had lower r-squared values, and some relationships were not statistically significant. NIR reflectance varied primarily as a function of leaf water content, and not independently as a function of turgor pressure, which is a sensitive indicator of leaf water status. The limitations of this approach to measuring plant water stress are discussed.

  20. Shrub encroachment alters sensitivity of soil respiration to temperature and moisture

    Science.gov (United States)

    Cable, Jessica M.; Barron-Gafford, Greg A.; Ogle, Kiona; Pavao-Zuckerman, Mitchell; Scott, Russell L.; Williams, David G.; Huxman, Travis E.

    2012-03-01

    A greater abundance of shrubs in semiarid grasslands affects the spatial patterns of soil temperature, moisture, and litter, resulting in fertile islands with potentially enhanced soil metabolic activity. The goal of this study was to quantify the microsite specificity of soil respiration in a semiarid riparian ecosystem experiencing shrub encroachment. We quantified the response of soil respiration to different microsite conditions created by big mesquite shrubs (near the trunk and the canopy edge), medium-sized mesquite, sacaton bunchgrasses, and open spaces. We hypothesized that soil respiration would be more temperature sensitive and less moisture sensitive and have a greater magnitude in shrub microsites compared with grass and open microsites. Field and incubation soil respiration data were simultaneously analyzed in a Bayesian framework to quantify the microsite-specific temperature and moisture sensitivities and magnitude of respiration. The analysis showed that shrub expansion increases the heterogeneity of respiration. Respiration has greater temperature sensitivity near the shrub canopy edge, and respiration rates are higher overall under big mesquite compared with those of the other microsites. Respiration in the microsites beneath medium-sized mesquites does not behave like a downscaled version of big mesquite microsites. The grass microsites show more similarity to big mesquite microsites than medium-sized shrubs. This study shows there can be a great deal of fine-scale spatial heterogeneity that accompanies shifts in vegetation structure. Such complexity presents a challenge in scaling soil respiration fluxes to the landscape for systems experiencing shrub encroachment, but quantifying this complexity is significantly important in determining overall ecosystem metabolic behavior.

  1. Respiration in Aquatic Insects.

    Science.gov (United States)

    MacFarland, John

    1985-01-01

    This article: (1) explains the respiratory patterns of several freshwater insects; (2) describes the differences and mechanisms of spiracular cutaneous, and gill respiration; and (3) discusses behavioral aspects of selected aquatic insects. (ML)

  2. Improvement of ballistocardiogram processing by inclusion of respiration information

    International Nuclear Information System (INIS)

    Tavakolian, Kouhyar; Vaseghi, Ali; Kaminska, Bozena

    2008-01-01

    In this paper a novel methodology for processing of a ballistocardiogram (BCG) is proposed in which the respiration signal is utilized to improve the averaging of the BCG signal and ultimately the annotation and interpretation of the signal. Previous research works filtered out the respiration signal while the novelty of the current research is that, rather than removing the respiration effect from the signal, we utilize the respiration information to improve the averaging and thus analysis and interpretation of the BCG signal in diagnosis of cardiac malfunctions. This methodology is based on our investigation that BCG cycles corresponding to the inspiration and expiration phases of the respiration cycle are different in morphology. BCG cycles corresponding to the expiration phase of respiration have been proved to be more closely related to each other when compared to cycles corresponding to inspiration, and therefore expiration cycles are better candidates to be selected for the calculation of the averaged BCG signal. The new BCG average calculated based on this methodology is then considered as the representative and a template of the BCG signal for further processing. This template can be considered as the output of a clinical BCG instrument with higher reliability and accuracy compared to the previous processing methods

  3. Simulation of Human Respiration with Breathing Thermal Manikin

    DEFF Research Database (Denmark)

    Bjørn, Erik

    The human respiration contains carbon dioxide, bioeffluents, and perhaps virus or bacteria. People may also indulge in activities that produce contaminants, as for example tobacco smoking. For these reasons, the human respiration remains one of the main contributors to contamination of the indoor...

  4. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    Directory of Open Access Journals (Sweden)

    Zhen Wang

    Full Text Available Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2.s(-1 and clipping (2.06 μmol.m(-2.s(-1 than under grazing (1.65 μmol.m-(2.s(-1 over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP. Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content and biotic (ANPP and BNPP factors regulate soil respiration in the semiarid temperate grassland of northern China.

  5. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    Science.gov (United States)

    Wang, Zhen; Ji, Lei; Hou, Xiangyang; Schellenberg, Michael P

    2016-01-01

    Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures) on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2).s(-1)) and clipping (2.06 μmol.m(-2).s(-1)) than under grazing (1.65 μmol.m-(2).s(-1)) over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP). Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP) and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content) and biotic (ANPP and BNPP) factors regulate soil respiration in the semiarid temperate grassland of northern China.

  6. Components of Soil Respiration and its Monthly Dynamics in Rubber Plantation Ecosystems

    OpenAIRE

    Zhixiang Wu; Limin Guan; Bangqian Chen; Chuan Yang; Guoyu Lan; Guishui Xie; Zhaode Zhou

    2014-01-01

    Aim: Our objective was to quantify four components and study effect factors of soil respiration in rubber plantation ecosystems. Providing the basic data support for the establishment of the trade of rubber plantation ecosystem carbon source/sink. Methods: We used Li-6400 (IRGA, Li-COR) to quantitate four components of soil respiration in rubber plantation ecosystems at different ages. Soil respiration can be separated as four components: heterotrophic respiration (Rh), Respiration of roots (...

  7. Can Leaf Spectroscopy Predict Leaf and Forest Traits Along a Peruvian Tropical Forest Elevation Gradient?

    Science.gov (United States)

    Doughty, Christopher E.; Santos-Andrade, P. E.; Goldsmith, G. R.; Blonder, B.; Shenkin, A.; Bentley, L. P.; Chavana-Bryant, C.; Huaraca-Huasco, W.; Díaz, S.; Salinas, N.; Enquist, B. J.; Martin, R.; Asner, G. P.; Malhi, Y.

    2017-11-01

    High-resolution spectroscopy can be used to measure leaf chemical and structural traits. Such leaf traits are often highly correlated to other traits, such as photosynthesis, through the leaf economics spectrum. We measured VNIR (visible-near infrared) leaf reflectance (400-1,075 nm) of sunlit and shaded leaves in 150 dominant species across ten, 1 ha plots along a 3,300 m elevation gradient in Peru (on 4,284 individual leaves). We used partial least squares (PLS) regression to compare leaf reflectance to chemical traits, such as nitrogen and phosphorus, structural traits, including leaf mass per area (LMA), branch wood density and leaf venation, and "higher-level" traits such as leaf photosynthetic capacity, leaf water repellency, and woody growth rates. Empirical models using leaf reflectance predicted leaf N and LMA (r2 > 30% and %RMSE < 30%), weakly predicted leaf venation, photosynthesis, and branch density (r2 between 10 and 35% and %RMSE between 10% and 65%), and did not predict leaf water repellency or woody growth rates (r2<5%). Prediction of higher-level traits such as photosynthesis and branch density is likely due to these traits correlations with LMA, a trait readily predicted with leaf spectroscopy.

  8. Soil respiration and photosynthetic uptake of carbon dioxide by ground-cover plants in four ages of jack pine forest

    Science.gov (United States)

    Striegl, Robert G.; Wickland, K.P.

    2001-01-01

    Soil carbon dioxide (CO2) emission (soil respiration), net CO2 exchange after photosynthetic uptake by ground-cover plants, and soil CO2 concentration versus depth below land surface were measured at four ages of jack pine (Pinus banksiana Lamb.) forest in central Saskatchewan. Soil respiration was smallest at a clear-cut site, largest in an 8-year-old stand, and decreased with stand age in 20-year-old and mature (60-75 years old) stands during May-September 1994 (12.1, 34.6, 31.5, and 24.9 mol C??m-2, respectively). Simulations of soil respiration at each stand based on continuously recorded soil temperature were within one standard deviation of measured flux for 48 of 52 measurement periods, but were 10%-30% less than linear interpolations of measured flux for the season. This was probably due to decreased soil respiration at night modeled by the temperature-flux relationships, but not documented by daytime chamber measurements. CO2 uptake by ground-cover plants ranged from 0 at the clear-cut site to 29, 25, and 9% of total growing season soil respiration at the 8-year, 20-year, and mature stands. CO2 concentrations were as great as 7150 ppmv in the upper 1 m of unsaturated zone and were proportional to measured soil respiration.

  9. Strong resilience of soil respiration components to drought-induced die-off resulting in forest secondary succession.

    Science.gov (United States)

    Barba, Josep; Curiel Yuste, Jorge; Poyatos, Rafael; Janssens, Ivan A; Lloret, Francisco

    2016-09-01

    How forests cope with drought-induced perturbations and how the dependence of soil respiration on environmental and biological drivers is affected in a warming and drying context are becoming key questions. The aims of this study were to determine whether drought-induced die-off and forest succession were reflected in soil respiration and its components and to determine the influence of climate on the soil respiration components. We used the mesh exclusion method to study seasonal variations in soil respiration (R S) and its components: heterotrophic (R H) and autotrophic (R A) [further split into fine root (R R) and mycorrhizal respiration (R M)] in a mixed Mediterranean forest where Scots pine (Pinus sylvestris L.) is undergoing a drought-induced die-off and is being replaced by holm oak (Quercus ilex L.). Drought-induced pine die-off was not reflected in R S nor in its components, which denotes a high functional resilience of the plant and soil system to pine die-off. However, the succession from Scots pine to holm oak resulted in a reduction of R H and thus in an important decrease of total respiration (R S was 36 % lower in holm oaks than in non-defoliated pines). Furthermore, R S and all its components were strongly regulated by soil water content-and-temperature interaction. Since Scots pine die-off and Quercus species colonization seems to be widely occurring at the driest limit of the Scots pine distribution, the functional resilience of the soil system over die-off and the decrease of R S from Scots pine to holm oak could have direct consequences for the C balance of these ecosystems.

  10. Mesozooplankton respiration and community structure in a seamount region of the eastern South Pacific

    Science.gov (United States)

    Frederick, Leissing; Escribano, Ruben; Morales, Carmen E.; Hormazabal, Samuel; Medellín-Mora, Johanna

    2018-05-01

    Seamounts in the Juan Fernandez Ridge, as well as in other seamount regions in the eastern South Pacific and in the world oceans, remain poorly studied ecosystems in terms of structure and functioning. Here, community respiration by epipelagic mesozooplankton in three seamounts of the Juan Fernandez Ridge, including the O`Higgins Seamount close to the coastal upwelling zone and two oceanic seamounts near the Juan Fernandez Archipelago ( 33°S-78°W), was assessed. Oxygen consumption by mixed assemblages was estimated using continuous measurements of dissolved oxygen concentration under controlled temperature during onboard, short-term incubations (2-4 h). Mesozooplankton composition was analyzed with a ZooScan device and expressed in terms of community normalized size spectra, and taxa and size diversity (Shannon-Wiener index). Carbon-specific community respiration rates in the upper 100 m layer were in the range of 0.3-1.9 mg O2 m-2 d-1, indicating that up to 3.1% of the mesozooplankton biomass can be respired on a daily basis. The mesozooplankton community was dominated by small-size copepods but the proportions of small copepods, large copepods, and gelatinous zooplankton (mostly salps) changed between the seamounts, in association with modifications in taxa composition, size diversity, and the slope of the size spectrum. Community respiration was significantly correlated to these community descriptors, suggesting the composition of the pelagic community has a direct impact on the total amount of respired-C. Connectivity between the coastal upwelling zone and the Juan Fernandez Ridge region mediated by mesoscale activity, interacting with the seamounts, is suggested as a most important process in controlling zooplankton community structure and in turn community metabolism.

  11. Changes in mitochondrial respiration in the human placenta over gestation.

    Science.gov (United States)

    Holland, Olivia J; Hickey, Anthony J R; Alvsaker, Anna; Moran, Stephanie; Hedges, Christopher; Chamley, Lawrence W; Perkins, Anthony V

    2017-09-01

    Placental mitochondria are subjected to micro-environmental changes throughout gestation, in particular large variations in oxygen. How placental mitochondrial respiration adapts to changing oxygen concentrations remains unexplored. Additionally, placental tissue is often studied in culture; however, the effect of culture on placental mitochondria is unclear. Placental tissue was obtained from first trimester and term (laboured and non-laboured) pregnancies, and selectively permeabilized to access mitochondria. Respirometry was used to compare respiration states and substrate use in mitochondria. Additionally, explants of placental tissue were cultured for four, 12, 24, 48, or 96 h and respiration measured. Mitochondrial respiration decreased at 11 weeks compared to earlier gestations (p = 0.05-0.001), and mitochondrial content increased at 12-13 weeks compared to 7-10 weeks (p = 0.042). In term placentae, oxidative phosphorylation (OXPHOS) through mitochondrial complex IV (p Respiration was increased (p ≤ 0.006-0.001) in laboured compared to non-laboured placenta. After four hours of culture, respiration was depressed compared to fresh tissue from the same placenta and continued to decline with time in culture. Markers of apoptosis were increased, while markers of autophagy, mitochondrial biogenesis, and mitochondrial membrane potential were decreased after four hours of culture. Respiration and mitochondrial content alter over gestation/with labour. Decreased respiration at 11 weeks and increased mitochondrial content at 12-13 weeks may relate to onset of maternal blood flow, and increased respiration as a result of labour may be an adaptation to ischaemia-reperfusion. At term, mitochondria were more susceptible to changes in respiratory function relative to first trimester when cultured in vitro, perhaps reflecting changes in metabolic demands as gestation progresses. Metabolic plasticity of placental mitochondria has relevance to placenta

  12. Leaf size and leaf display of thirty-eight tropical tree species

    NARCIS (Netherlands)

    Poorter, L.; Rozendaal, D.M.A.

    2008-01-01

    Trees forage for light through optimal leaf display. Effective leaf display is determined by metamer traits (i.e., the internode, petiole, and corresponding leaf), and thus these traits strongly co-determine carbon gain and as a result competitive advantage in a light-limited environment. We

  13. Glycolysis-respiration relationships in a neuroblastoma cell line.

    Science.gov (United States)

    Swerdlow, Russell H; E, Lezi; Aires, Daniel; Lu, Jianghua

    2013-04-01

    Although some reciprocal glycolysis-respiration relationships are well recognized, the relationship between reduced glycolysis flux and mitochondrial respiration has not been critically characterized. We concomitantly measured the extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) of SH-SY5Y neuroblastoma cells under free and restricted glycolysis flux conditions. Under conditions of fixed energy demand ECAR and OCR values showed a reciprocal relationship. In addition to observing an expected Crabtree effect in which increasing glucose availability raised the ECAR and reduced the OCR, a novel reciprocal relationship was documented in which reducing the ECAR via glucose deprivation or glycolysis inhibition increased the OCR. Substituting galactose for glucose, which reduces net glycolysis ATP yield without blocking glycolysis flux, similarly reduced the ECAR and increased the OCR. We further determined how reduced ECAR conditions affect proteins that associate with energy sensing and energy response pathways. ERK phosphorylation, SIRT1, and HIF1a decreased while AKT, p38, and AMPK phosphorylation increased. These data document a novel intracellular glycolysis-respiration effect in which restricting glycolysis flux increases mitochondrial respiration. Since this effect can be used to manipulate cell bioenergetic infrastructures, this particular glycolysis-respiration effect can practically inform the development of new mitochondrial medicine approaches. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Plant traits and environment: floating leaf blade production and turnover of waterlilies.

    Science.gov (United States)

    Klok, Peter F; van der Velde, Gerard

    2017-01-01

    Floating leaf blades of waterlilies fulfill several functions in wetland ecosystems by production, decomposition and turnover as well as exchange processes. Production and turnover rates of floating leaf blades of three waterlily species, Nuphar lutea (L.) Sm., Nymphaea alba L. and Nymphaea candida Presl, were studied in three freshwater bodies, differing in trophic status, pH and alkalinity. Length and percentages of leaf loss of marked leaf blades were measured weekly during the growing season. Area and biomass were calculated based on leaf length and were used to calculate the turnover rate of floating leaf blades. Seasonal changes in floating leaf production showed that values decreased in the order: Nymphaea alba , Nuphar lutea , Nymphaea candida . The highest production was reached for Nuphar lutea and Nymphaea alba in alkaline, eutrophic water bodies. The production per leaf was relatively high for both species in the acid water body. Nymphaea candida showed a very short vegetation period and low turnover rates. The ratio Total potential leaf biomass/Maximum potential leaf biomass (P/B max ) of the three species ranged from 1.35-2.25. The ratio Vegetation period (Period with floating leaves)/Mean leaf life span ranged from 2.94-4.63, the ratio Growth period (Period with appearance of new floating leaves)/Vegetation period from 0.53-0.73. The clear differences between Nymphaea candida versus Nuphar lutea and Nymphaea alba , may be due to adaptations of Nymphaea candida to an Euro-Siberic climate with short-lasting summer conditions.

  15. Respiration-to-DNA ratio reflects physiological state of microorganisms in root-free and rhizosphere soil

    Science.gov (United States)

    Blagodatskaya, E.; Blagodatsky, S.; Kuzyakov, Y.

    2009-04-01

    VCO2-to-total DNA ratios were lower than 0.1 µg CO2-C µg-1 total DNA h-1 whereas during exponential microbial growth these values increased consistently and exceeded 1 µg CO2-C µg-1 DNA h-1. Thus, the VCO2-to-total DNA ratio strongly changes along with the physiological state of soil microorganisms and can be used as valuable physiological parameter. In growing microorganisms the quantity of CO2 evolved per unit of newly formed DNA was identical in rhizosphere and root free soil and averaged for 13.5 ± 1.1 µg CO2-C µg-1 newly formed DNA. The CO2 yield per unit of newly formed DNA allows the estimation of microbial growth efficiency and validation of specific growth rates obtained during kinetic analysis of respiration curves. The study was supported by European Commission (Marie Curie IIF program, project MICROSOM) and by Alexander von Humboldt Foundation. References: Blagodatskaya EV, Blagodatskii SA, Anderson TH. 2003. Quantitative Isolation of Microbial DNA from Different Types of Soils of Natural and Agricultural Ecosystems. Microbiology 72(6):744-749. Blagodatsky SA, Heinemeyer O, Richter J. 2000. Estimating the active and total soil microbial biomass by kinetic respiration analysis. Biology and Fertility of Soils 32(1):73-81.

  16. Simultaneous minimizing monitor units and number of segments without leaf end abutment for segmental intensity modulated radiation therapy delivery

    International Nuclear Information System (INIS)

    Li Kaile; Dai Jianrong; Ma Lijun

    2004-01-01

    Leaf end abutment is seldom studied when delivering segmental intensity modulated radiation therapy (IMRT) fields. We developed an efficient leaf sequencing method to eliminate leaf end abutment for segmental IMRT delivery. Our method uses simple matrix and sorting operations to obtain a solution that simultaneously minimizes total monitor units and number of segments without leaf end abutment between segments. We implemented and demonstrated our method for multiple clinical cases. We compared the results of our method with the results from exhaustive search method. We found that our solution without leaf end abutment produced equivalent results to the unconstrained solutions in terms of minimum total monitor units and minimum number of leaf segments. We conclude that the leaf end abutment fields can be avoided without affecting the efficiency of segmental IMRT delivery. The major strength of our method is its simplicity and high computing speed. This potentially provides a useful means for generating segmental IMRT fields that require high spatial resolution or complex intensity distributions

  17. Evaluation of Methane from Sisal Leaf Residue and Palash Leaf Litter

    Science.gov (United States)

    Arisutha, S.; Baredar, P.; Deshpande, D. M.; Suresh, S.

    2014-12-01

    The aim of this study is to evaluate methane production from sisal leaf residue and palash leaf litter mixed with different bulky materials such as vegetable market waste, hostel kitchen waste and digested biogas slurry in a laboratory scale anaerobic reactor. The mixture was prepared with 1:1 proportion. Maximum methane content of 320 ml/day was observed in the case of sisal leaf residue mixed with vegetable market waste as the feed. Methane content was minimum (47 ml/day), when palash leaf litter was used as feed. This was due to the increased content of lignin and polyphenol in the feedstock which were of complex structure and did not get degraded directly by microorganisms. Sisal leaf residue mixtures also showed highest content of volatile fatty acids (VFAs) as compared to palash leaf litter mixtures. It was observed that VFA concentration in the digester first increased, reached maximum (when pH was minimum) and then decreased.

  18. Implications of CO2 pooling on delta13C of ecosystem respiration and leaves in Amazonian forest

    Science.gov (United States)

    de Araújo, A. C.; Ometto, J. P. H. B.; Dolman, A. J.; Kruijt, B.; Waterloo, M. J.; Ehleringer, J. R.

    2008-05-01

    The carbon isotope of a leaf (δ13Cleaf) is generally more negative in riparian zones than in areas with low soil moisture content or rainfall input. In Central Amazonia, the small-scale topography is composed of plateaus and valleys, with plateaus generally having a lower soil moisture status than the valley edges in the dry season. Yet in the dry season, the nocturnal accumulation of CO2 is higher in the valleys than on the plateaus. Samples of sunlit leaves and atmospheric air were collected along a topographical gradient in the dry season to test whether the δ13Cleaf of sunlit leaves and the carbon isotope ratio of ecosystem respired CO2 (δ13CReco) may be more negative in the valley than those on the plateau. The δ13Cleaf was significantly more negative in the valley than on the plateau. Factors considered to be driving the observed variability in δ13Cleaf were: leaf nitrogen concentration, leaf mass per unit area (LMA), soil moisture availability, more negative carbon isotope ratio of atmospheric CO2 (δ13Ca) in the valleys during daytime hours, and leaf discrimination (Δleaf). The observed pattern of δ13Cleaf might suggest that water-use efficiency (WUE) is higher on the plateaus than in the valleys. However, there was no full supporting evidence for this because it remains unclear how much of the difference in δ13Cleaf was driven by physiology or &delta13Ca. The δ13CReco was more negative in the valleys than on the plateaus on some nights, whereas in others it was not. It is likely that lateral drainage of CO2 enriched in 13C from upslope areas might have happened when the nights were less stable. Biotic factors such as soil CO2 efflux (Rsoil) and the responses of plants to environmental variables such as vapor pressure deficit (D) may also play a role. The preferential pooling of CO2 in the low-lying areas of this landscape may confound the interpretation of δ13Cleaf and δ13CReco.

  19. Implications of CO2 pooling on δ13C of ecosystem respiration and leaves in Amazonian forest

    Directory of Open Access Journals (Sweden)

    M. J. Waterloo

    2008-05-01

    Full Text Available The carbon isotope of a leaf (δ13Cleaf is generally more negative in riparian zones than in areas with low soil moisture content or rainfall input. In Central Amazonia, the small-scale topography is composed of plateaus and valleys, with plateaus generally having a lower soil moisture status than the valley edges in the dry season. Yet in the dry season, the nocturnal accumulation of CO2 is higher in the valleys than on the plateaus. Samples of sunlit leaves and atmospheric air were collected along a topographical gradient in the dry season to test whether the δ13Cleaf of sunlit leaves and the carbon isotope ratio of ecosystem respired CO2 (δ13CReco may be more negative in the valley than those on the plateau. The δ13Cleaf was significantly more negative in the valley than on the plateau. Factors considered to be driving the observed variability in δ13Cleaf were: leaf nitrogen concentration, leaf mass per unit area (LMA, soil moisture availability, more negative carbon isotope ratio of atmospheric CO2 (δ13Ca in the valleys during daytime hours, and leaf discrimination (Δleaf. The observed pattern of δ13Cleaf might suggest that water-use efficiency (WUE is higher on the plateaus than in the valleys. However, there was no full supporting evidence for this because it remains unclear how much of the difference in δ13Cleaf was driven by physiology or &delta13Ca. The δ13CReco was more negative in the valleys than on the plateaus on some nights, whereas in others it was not. It is likely that lateral drainage of CO2 enriched in 13C from upslope areas might have happened when the nights were less stable. Biotic factors such as soil CO2 efflux (Rsoil and the responses of plants to environmental variables such as vapor pressure deficit (D may also play a role. The preferential pooling of CO2 in the low-lying areas of this landscape may confound the interpretation of δ13Cleaf and δ13CReco.

  20. CO2 and temperature effects on leaf area production in two annual plant species

    International Nuclear Information System (INIS)

    Ackerly, D.D.; Coleman, J.S.; Morse, S.R.; Bazzaz, F.A.

    1992-01-01

    The authors studied leaf area production in two annual plant species, Abutilon theophrasti and Amaranthus retroflexus, under three day/night temperature regimes and two concentrations of carbon dioxide. The production of whole-plant leaf area during the first 30 d of growth was analyzed in terms of the leaf initiation rate, leaf expansion, individual leaf area, and, in Amaranthus, production of branch leaves. Temperature and CO 2 influenced leaf area production through effects on the rate of development, determined by the production of nodes on the main stem, and through shifts in the relationship between whole-plant leaf area and the number of main stem nodes. In Abutilon, leaf initiation rate was highest at 38 degree, but area of individual leaves was greatest at 28 degree. Total leaf area was greatly reduced at 18 degree due to slow leaf initiation rates. Elevated CO 2 concentration increased leaf initiation rate at 28 degree, resulting in an increase in whole-part leaf area. In Amaranthus, leaf initiation rate increased with temperature, and was increased by elevated CO 2 at 28 degree. Individual leaf area was greatest at 28 degree, and was increased by elevated CO 2 at 28 degree but decreased at 38 degree. Branch leaf area displayed a similar response to CO 2 , butt was greater at 38 degree. Overall, wholeplant leaf area was slightly increased at 38 degree relative to 28 degree, and elevated CO 2 levels resulted in increased leaf area at 28 degree but decreased leaf area at 38 degree

  1. ‘Breath figures’ on leaf surfaces – formation and effects of microscopic leaf wetness

    Directory of Open Access Journals (Sweden)

    Jürgen eBurkhardt

    2013-10-01

    Full Text Available ‘Microscopic leaf wetness’ means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 µm, microscopic leaf wetness it is about 2 orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the amount and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g. ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past.

  2. Nutritional evaluation of bitter leaf meal ( Vernonia amygdalina ...

    African Journals Online (AJOL)

    Nutritional evaluation of bitter leaf meal ( Vernonia amygdalina ): effects on ... A total of 72 one-day-old broiler chicks of Abor-acre breed were used for the trial and ... reduced the level of cholesterol, triglyceride, glucose, low density lipoprotein, ...

  3. Photosynthesis, respiration, and carbon turnover in sinking marine snow from surface waters of Southern California Bight: implications for the carbon cycle in the ocean

    DEFF Research Database (Denmark)

    Ploug, Helle; Grossart, Hans-Peter; Azam, F.

    1999-01-01

    Photosynthesis and respiration were measured in 1 to 6 mm large aggregates (marine snow) collected in the Southern Californian Eight, USA. The aggregates were freely sinking in a vertical flow system with an upward flow velocity which opposed the sinking velocity of individual aggregates during...... techniques. Both the respiration rate per aggregate volume and the bacterial densities decreased with increasing aggregate size. The respiration rates normalized to the number of bacteria in single aggregates were 7.4 to 70 fmol C cell(-1) d(-1). The aggregate community respired 433 to 984 ng C d(-1) per...... aggregate in darkness, which yielded a turnover time of 8 to 9 d for the total organic carbon in aggregates. Thus, marine snow is not only a vehicle for vertical flux of organic matter; the aggregates are also hotspots of microbial respiration which cause a fast and efficient respiratory turnover...

  4. Insulin resistance in HIV-infected youth is associated with decreased mitochondrial respiration.

    Science.gov (United States)

    Takemoto, Jody K; Miller, Tracie L; Wang, Jiajia; Jacobson, Denise L; Geffner, Mitchell E; Van Dyke, Russell B; Gerschenson, Mariana

    2017-01-02

    To identify relationships between insulin resistance (IR) and mitochondrial respiration in perinatally HIV-infected youth. Case-control study. Mitochondrial respiration was assessed in perinatally HIV-infected youth in Tanner stages 2-5, 25 youth with IR (IR+) and 50 without IR (IR-) who were enrolled in the Pediatric HIV/AIDS Cohort Study. IR was defined as a homeostatic model of assessment for IR value at least 4.0. A novel, high-throughput oximetry method was used to evaluate cellular respiration in peripheral blood mononuclear cells. Unadjusted and adjusted differences in mitochondrial respiration markers between IR+ and IR- were evaluated, as were correlations between mitochondrial respiration markers and biochemical measurements. IR+ and IR- youth were similar on age, sex, and race/ethnicity. Mean age was 16.5 and 15.6 years in IR+ and IR-, respectively. The IR+ group had significantly higher mean BMI and metabolic analytes (fasting glucose, insulin, cholesterol, triglycerides, and venous lactate and pyruvate) compared with the IR-. Mitochondrial respiration markers were, on average, lower in the IR+ compared with IR-, including basal respiration (417.5 vs. 597.5 pmol, P = 0.074), ATP production (11 513 vs. 15 202 pmol, P = 0.078), proton leak (584.6 vs. 790.0 pmol, P = 0.033), maximal respiration (1815 vs. 2399 pmol, P = 0.025), and spare respiration capacity (1162 vs. 2017 pmol, P = 0.032). Nonmitochondrial respiration did not differ by IR status. The results did not change when adjusted for age. HIV-infected youth with IR have lower mitochondrial respiration markers when compared to youth without IR. Disordered mitochondrial respiration may be a potential mechanism for IR in this population.

  5. Can we relate respiration rates of bark and wood with tissue nitrogen concentrations and branch-level CO2 fluxes across woody species?

    Science.gov (United States)

    Eller, A. S.; Wright, I.; Cernusak, L. A.

    2013-12-01

    Respiration from above-ground woody tissue is generally responsible for 5-15% of ecosystem respiration (~ 30% of total above-ground respiration). The CO2 respired by branches comes from both the sapwood and the living layers within the bark, but because there is considerable movement of respired CO2 within woody tissues (e.g. in the transpiration stream), and because the bark can present a considerable barrier to CO2 diffusion, it can be difficult to interpret measured CO2 efflux from intact branches in relation to the respiration rates of the component tissues, and to relative mass allocation to each. In this study we investigated these issues in 15 evergreen tree and shrub species native to the Sydney area in eastern Australia. We measured CO2 efflux and light-dependent refixation of respired CO2 in photosynthetic bark from the exterior surfaces of branches (0.5-1.5 cm in diameter), and measured the tissue-specific respiration rates of the bark and wood from those same branches. We also measured the nitrogen content and tissue density of the wood and bark to determine: 1) Among species, what is the relationship between %N and tissue respiration? 2) How is photosynthetic refixation of CO2 related to respiration and %N in the bark and underlying wood? and 3) What is the relationship between branch CO2 efflux and the respiration rates of the underlying wood and bark that make up the branch? Across the 15 species %N was a better predictor of respiration in wood than in bark. CO2 efflux measured from the exterior of the stem in the dark was positively correlated with photosynthetic refixation and explained ~40% of the variation in rates of refixation. Refixation rates were not strongly related to bark or wood %N. Differences among species in CO2 efflux rates were not well explained by differences in bark or wood %N and there was a stronger relationship between bark respiration and CO2 efflux than between wood respiration and CO2 efflux. These results suggest that the

  6. Soil Respiration and Student Inquiry: A Perfect Match

    Science.gov (United States)

    Hoyt, Catherine Marie; Wallenstein, Matthew David

    2011-01-01

    This activity explores the cycling of carbon between the atmosphere (primarily as CO[subscript 2]) and biomass in plants, animals, and microscopic organisms. Students design soil respiration experiments using a protocol that resembles current practice in soil ecology. Three methods for measuring soil respiration are presented. Student-derived…

  7. Phytochemical analysis and gastroprotective activity of an olive leaf extract

    Directory of Open Access Journals (Sweden)

    IVANA ARSIĆ

    2009-04-01

    Full Text Available Some medicinal features of olive leaf have been known for centuries. It has been traditionally used as an antimicrobial and to prevent and treat diabetes mellitus and heart disease. Whether olive leaf, a natural antioxidant, influences the gastric defense mechanism and exhibits gastroprotection against experimentally-induced gastric lesions remains unknown. In this study, the content of total phenols, total flavonoids and tannins in olive leaf extract (OLE were determined. Seven phenolic compounds were identified and quantified (oleuropein, caffeic acid, luteolin, luteolin-7-O-glucoside, apigenin-7-O-glucoside, quercetin, and chryseriol. Furthermore, the protective activity of the OLE in gastric mucosal injury induced by a corrosive concentration of ethanol was investigated. In relation to the control group, pretreatment with OLE (40, 80 and 120 mg kg-1 significantly (p < 0.001 attenuated the gastric lesions induced by absolute ethanol. The protective effect of the OLE was similar to that obtained with a reference drug, ranitidine. The results obtained indicate that OLE possesses significant gastroprotective activity, and that the presence of compounds with antioxidative properties would probably explain this effect.

  8. Effect of subchronic administration of ethanolic leaf extract of croton ...

    African Journals Online (AJOL)

    The biochemical effcts of ethanolic leaf extract of Croton zambesicus on serum alkaline phosphatase(SAP),aspartate aminotransferase (AST) ,alanine aminotransferase(ALT),serum total protein and albumin were studied.The levels of these enzymes and that of total protein and albumin in the extract treated rats were not ...

  9. Does the increased air humidity affect soil respiration and carbon stocks?

    Science.gov (United States)

    Kukumägi, Mai; Celi, Luisella; Said-Pullicino, Daniel; Kupper, Priit; Sõber, Jaak; Lõhmus, Krista; Kutti, Sander; Ostonen, Ivika

    2013-04-01

    Climate manipulation experiments at ecosystem-scale enable us to simulate, investigate and predict changes in carbon balance of forest ecosystems. Considering the predicted increase in air humidity and precipitation for northern latitudes, this work aimed at investigating the effect of increased air humidity on soil respiration, distribution of soil organic matter (SOM) among pools having different turnover times, and microbial, fine root and rhizome biomass. The study was carried out in silver birch (Betula pendula Roth.) and hybrid aspen (Populus tremula L. × P. tremuloides Michx.) stands in a Free Air Humidity Manipulation (FAHM) experimental facility containing three humidified (H; on average 7% above current ambient levels since 2008) and three control (C) plots. Soil respiration rates were measured monthly during the growing season using a closed dynamic chamber method. Density fractionation was adopted to separate SOM into two light fractions (free and aggregate-occluded particulate organic matter, fPOM and oPOM respectively), and one heavy fraction (mineral-associated organic matter, MOM). The fine root and rhizome biomass and microbial data are presented for silver birch stands only. In 2011, after 4 growing seasons of humidity manipulation soil organic carbon contents were significantly higher in C plots than H plot (13.5 and 12.5 g C kg-1, respectively), while soil respiration tended to be higher in the latter. Microbial biomass and basal respiration were 13 and 14% higher in H plots than in the C plots, respectively. Twice more fine roots of trees were estimated in H plots, while the total fine root and rhizome biomass (tree + understory) was similar in C and H plots. Fine root turnover was higher for both silver birch and understory roots in H plots. Labile SOM light fractions (fPOM and oPOM) were significantly smaller in H plots with respect to C plots (silver birch and hybrid aspen stands together), whereas no differences were observed in the

  10. Short-term acclimation to warmer temperatures accelerates leaf carbon exchange processes across plant types.

    Science.gov (United States)

    Smith, Nicholas G; Dukes, Jeffrey S

    2017-11-01

    While temperature responses of photosynthesis and plant respiration are known to acclimate over time in many species, few studies have been designed to directly compare process-level differences in acclimation capacity among plant types. We assessed short-term (7 day) temperature acclimation of the maximum rate of Rubisco carboxylation (V cmax ), the maximum rate of electron transport (J max ), the maximum rate of phosphoenolpyruvate carboxylase carboxylation (V pmax ), and foliar dark respiration (R d ) in 22 plant species that varied in lifespan (annual and perennial), photosynthetic pathway (C 3 and C 4 ), and climate of origin (tropical and nontropical) grown under fertilized, well-watered conditions. In general, acclimation to warmer temperatures increased the rate of each process. The relative increase in different photosynthetic processes varied by plant type, with C 3 species tending to preferentially accelerate CO 2 -limited photosynthetic processes and respiration and C 4 species tending to preferentially accelerate light-limited photosynthetic processes under warmer conditions. R d acclimation to warmer temperatures caused a reduction in temperature sensitivity that resulted in slower rates at high leaf temperatures. R d acclimation was similar across plant types. These results suggest that temperature acclimation of the biochemical processes that underlie plant carbon exchange is common across different plant types, but that acclimation to warmer temperatures tends to have a relatively greater positive effect on the processes most limiting to carbon assimilation, which differ by plant type. The acclimation responses observed here suggest that warmer conditions should lead to increased rates of carbon assimilation when water and nutrients are not limiting. © 2017 John Wiley & Sons Ltd.

  11. Ecosystem respiration, methane and nitrous oxide fluxes from ecotopes in a rewetted extracted peatland in Sweden

    Directory of Open Access Journals (Sweden)

    S. Jordan

    2016-09-01

    Full Text Available Ecosystem respiration (carbon dioxide; CO2, methane (CH4 and nitrous oxide (N2O fluxes to the atmosphere were determined using an opaque closed chamber method within various ecotopes (vegetation covered, bare peat and open water in a rewetted extracted peatland and within an adjacent open poor fen in Sweden. Ecotopes had a significant impact on CO2 and CH4 fluxes to the atmosphere. Ecosystem respiration and CH4 emissions from the bare peat site, the constructed shallow lake and the open poor fen were low but were much higher from ecotopes with Eriophorum vaginatum tussocks and Eriophorum angustifolium. A combination of vascular plant cover and high soil temperatures enhanced ecosystem respiration, while a combination of vascular plant cover, high water table levels and high soil temperatures enhanced CH4 emissions. N2O emissions contributed little to total greenhouse gas (GHG fluxes from the soil-plant-water systems to the atmosphere. However, the overall climate impact of CH4 emissions from the study area did not exceed the impact of soil and plant respiration. With regard to management of extracted peatlands, the construction of a nutrient-poor shallow lake showed great potential for lowering GHG fluxes to the atmosphere.

  12. Combined effects of leaf litter and soil microsite on decomposition process in arid rangelands.

    Science.gov (United States)

    Carrera, Analía Lorena; Bertiller, Mónica Beatriz

    2013-01-15

    The objective of this study was to analyze the combined effects of leaf litter quality and soil properties on litter decomposition and soil nitrogen (N) mineralization at conserved (C) and disturbed by sheep grazing (D) vegetation states in arid rangelands of the Patagonian Monte. It was hypothesized that spatial differences in soil inorganic-N levels have larger impact on decomposition processes of non-recalcitrant than recalcitrant leaf litter (low and high concentration of secondary compounds, respectively). Leaf litter and upper soil were extracted from modal size plant patches (patch microsite) and the associated inter-patch area (inter-patch microsite) in C and D. Leaf litter was pooled per vegetation state and soil was pooled combining vegetation state and microsite. Concentrations of N and secondary compounds in leaf litter and total and inorganic-N in soil were assessed at each pooled sample. Leaf litter decay and soil N mineralization at microsites of C and D were estimated in 160 microcosms incubated at field capacity (16 month). C soils had higher total N than D soils (0.58 and 0.41 mg/g, respectively). Patch soil of C and inter-patch soil of D exhibited the highest values of inorganic-N (8.8 and 8.4 μg/g, respectively). Leaf litter of C was less recalcitrant and decomposed faster than that of D. Non-recalcitrant leaf litter decay and induced soil N mineralization had larger variation among microsites (coefficients of variation = 25 and 41%, respectively) than recalcitrant leaf litter (coefficients of variation = 12 and 32%, respectively). Changes in the canopy structure induced by grazing disturbance increased leaf litter recalcitrance, and reduced litter decay and soil N mineralization, independently of soil N levels. This highlights the importance of the combined effects of soil and leaf litter properties on N cycling probably with consequences for vegetation reestablishment and dynamics, rangeland resistance and resilience with implications

  13. Assessment of hepatoprotective role of Eucalyptus tereticornis leaf extract in Rattus norvegicus after vanadium intoxication

    International Nuclear Information System (INIS)

    Saxena, Prabhu N.; Shukla, Aparna; Saxena, Nishi; Arya, Jyoti

    2010-01-01

    The protective effect of Eucalyptus tereticornis leaf extract and its potency has been compared with Liv.52 following V 2 O 5 , induced hepatotoxicity in albino rats. LD 50 estimated for V 2 O 5 , was 69.6 mg/kg b.wt. The administered doses of V 2 O 5 , were LD 50 /10 th for acute and 1/7 th , 1/14 th and 1/21 th of sublethal dose for subacute (7, 14 and 21 ds) respectively. Body weight, liver weight and hepatosomatic index were assessed. Hepatotoxicity was assessed in terms of hepatic total proteins, total lipids and total cholesterol. V 2 O 5 intoxication significantly increased liver weight, hepatosomatic index, total lipids and total cholesterol, while significantly decreased body weight and total proteins. Pretreatment with dose of 100 mg/kg b.wt of Eucalyptus tereticornis leaf extract and 0.125 ml/kg b.wt. of Liv.52 syrup restored the increased liver weight, hepatosomatic index, total lipids and total cholesterol and decreased parameters like body weight and total proteins toward normalcy. The results reveal that Eucalyptus tereticornis leaf extract modulates V 2 O 5 toxicity like well known hepatoprotectant, however the modulation is less than Liv.52. (author)

  14. Stimulation of respiration in rat thymocytes induced by ionizing radiation

    International Nuclear Information System (INIS)

    Gudz, T.I.; Pandelova, I.G.; Novgorodov, S.A.

    1994-01-01

    The effect of X irradiation on the respiration of rat thymocytes was studied. An increase in the rate of O 2 uptake was observed 1 h after cells were irradiated with doses of 6-10 Gy. The radiation-induced increase in respiration could be blocked by oligomycin, an inhibitor of mitochondrial ATP synthase, suggesting control by increased cytoplasmic ATP turnover. The stimulation of respiration was not associated with changes in the activity of mitochondrial electron transfer enzymes or permeability of the inner membrane. Several inhibitors of processes which used ATP were screened for their effects on the basal respiration rate and on the radiation response. In irradiated thymocytes, an enhancement of inhibition of respiration by ouabain, La 3+ and cycloheximide was observed. These results indicate that the radiation-induced stimulation of respiration is due to changes in ion homeostasis and protein synthesis. The effect of X irradiation was shown to be independent of the redox status of nonprotein thiols and was not associated with detectable changes in some products of lipid peroxidation. The radiation-induced decrease in activity of superoxide dismutase suggests free radical involvement in deleterious effects of radiation. 43 refs., 2 figs., 3 tabs

  15. Influence of spectral properties on cassava leaf development and ...

    African Journals Online (AJOL)

    sunny t

    2014-02-12

    Feb 12, 2014 ... changes in leaf spectral characteristics were studied using Digimizer ... main wavelengths used by plants (blue, green and red) with the blue being the most preferred. Total ...... differences observed allude to plant behavior.

  16. Leaf rust of cultivated barley: pathology and control.

    Science.gov (United States)

    Park, Robert F; Golegaonkar, Prashant G; Derevnina, Lida; Sandhu, Karanjeet S; Karaoglu, Haydar; Elmansour, Huda M; Dracatos, Peter M; Singh, Davinder

    2015-01-01

    Leaf rust of barley is caused by the macrocyclic, heteroecious rust pathogen Puccinia hordei, with aecia reported from selected species of the genera Ornithogalum, Leopoldia, and Dipcadi, and uredinia and telia occurring on Hordeum vulgare, H. vulgare ssp. spontaneum, Hordeum bulbosum, and Hordeum murinum, on which distinct parasitic specialization occurs. Although Puccinia hordei is sporadic in its occurrence, it is probably the most common and widely distributed rust disease of barley. Leaf rust has increased in importance in recent decades in temperate barley-growing regions, presumably because of more intensive agricultural practices. Although total crop loss does not occur, under epidemic conditions yield reductions of up to 62% have been reported in susceptible varieties. Leaf rust is primarily controlled by the use of resistant cultivars, and, to date, 21 seedling resistance genes and two adult plant resistance (APR) genes have been identified. Virulence has been detected for most seedling resistance genes but is unknown for the APR genes Rph20 and Rph23. Other potentially new sources of APR have been reported, and additivity has been described for some of these resistances. Approaches to achieving durable resistance to leaf rust in barley are discussed.

  17. Supplementation of Red Betel Leaf (Piper crocatum in Dairy Cattle Feed on Fermentation Characteristics by in Vitro

    Directory of Open Access Journals (Sweden)

    Caribu Hadi Prayitno

    2016-05-01

    Full Text Available The aim of this study was to assess the impact and efficiency of red betel leaf’s extract supplementation in the diet of dairy cattle on fermentation characteristics by in vitro.  The research method was experiment by using completely randomized design.  The treatments that were tested were R1: basal feed, R2:  R1 + 15 ppm of  red betel  leaf (Piper crocatum extract, R3: R1 + 30 ppm of  red betel leaf (Piper crocatum extract, R4: R1 + 45 ppm of red betel leaf (Piper crocatum extract, R5: R1 + 60 ppm of red betel leaf (Piper crocatum extract. The parameters measured in this study were (1Dry MatterDigestibility (DMD,(2Organic Matter Digestibility (OMD  (3 total gas production  (4 methane production (CH4 and (5  total Volatille Fatty Acid (VFA.  The data were analyzed using analysis of variance followed Orthogonal Polynomial Test.The results showed that the suplementation red batel extract in the diet of dairy cow was significant (P < 0.01 on DMD, OMD, total gas production, methane production (CH4  and total VFA.Orthogonal Polynomial test showed the effect of treatment on Dry MatterDigestibility (DMD, total gas and CH4 gas production were in the form of cubic curve, as well as Organic Matter Digestibility (OMD and Volatille Fatty Acid (VFA in the form of quadrate curvewith supplementation of red betel leaf.

  18. Plant traits and environment: floating leaf blade production and turnover of waterlilies

    Directory of Open Access Journals (Sweden)

    Peter F. Klok

    2017-04-01

    Full Text Available Floating leaf blades of waterlilies fulfill several functions in wetland ecosystems by production, decomposition and turnover as well as exchange processes. Production and turnover rates of floating leaf blades of three waterlily species, Nuphar lutea (L. Sm., Nymphaea alba L. and Nymphaea candida Presl, were studied in three freshwater bodies, differing in trophic status, pH and alkalinity. Length and percentages of leaf loss of marked leaf blades were measured weekly during the growing season. Area and biomass were calculated based on leaf length and were used to calculate the turnover rate of floating leaf blades. Seasonal changes in floating leaf production showed that values decreased in the order: Nymphaea alba, Nuphar lutea, Nymphaea candida. The highest production was reached for Nuphar lutea and Nymphaea alba in alkaline, eutrophic water bodies. The production per leaf was relatively high for both species in the acid water body. Nymphaea candida showed a very short vegetation period and low turnover rates. The ratio Total potential leaf biomass/Maximum potential leaf biomass (P/Bmax of the three species ranged from 1.35–2.25. The ratio Vegetation period (Period with floating leaves/Mean leaf life span ranged from 2.94–4.63, the ratio Growth period (Period with appearance of new floating leaves/Vegetation period from 0.53–0.73. The clear differences between Nymphaea candida versus Nuphar lutea and Nymphaea alba, may be due to adaptations of Nymphaea candida to an Euro-Siberic climate with short-lasting summer conditions.

  19. Effects of combination of leaf resources on competition in container mosquito larvae.

    Science.gov (United States)

    Reiskind, M H; Zarrabi, A A; Lounibos, L P

    2012-08-01

    Resource diversity is critical to fitness in many insect species, and may determine the coexistence of competitive species and the function of ecosystems. Plant material provides the nutritional base for numerous aquatic systems, yet the consequences of diversity of plant material have not been studied in aquatic container systems important for the production of mosquitoes. To address how diversity in leaf detritus affects container-inhabiting mosquitoes, we examined how leaf species affect competition between two container inhabiting mosquito larvae, Aedes aegypti and Aedes albopictus, that co-occur in many parts of the world. We tested the hypotheses that leaf species changes the outcome of intra- and interspecific competition between these mosquito species, and that combinations of leaf species affect competition in a manner not predictable based upon the response to each leaf species alone (i.e. the response to leaf combinations is non-additive). We find support for our first hypothesis that leaf species can affect competition, evidence that, in general, leaf combination alters competitive interactions, and no support that leaf combination impacts interspecific competition differently than intraspecific competition. We conclude that combinations of leaves increase mosquito production non-additively such that combinations of leaves act synergistically, in general, and result in higher total yield of adult mosquitoes in most cases, although certain leaf combinations for A. albopictus are antagonistic. We also conclude that leaf diversity does not have a different effect on interspecific competition between A. aegypti and A. albopictus, relative to intraspecific competition for each mosquito.

  20. Acute toxicity of Nerium oleander aqueous leaf extract in rabbits

    Directory of Open Access Journals (Sweden)

    B. A. Al-Badrani

    2008-01-01

    Full Text Available The median lethal dose was evaluated in rabbits subcutaneously injected with Nerium oleander aqueous leaf extract . The clinical signs , postmortem changes , hematological and biochemical changes were recorded. The results revealed that the median lethal dose was 157.37 mg / kg B. wt. The live animals showed nervous signs in the second days after treatment as crying, ataxia , abdominal respiration , inaddition to a significant increase in body temperature and loss in the body weigth then all animals die during 4 -5 day.The postmortem changes included hemorrhages , and congestion in all organs particularly in the subcutaneous tissue. Hematological changes including increase in the packed cell volume and hemoglobin concentration ,and erythrocytic count and leukocytosis with neutrophilia and lymphopenia .Significant increase in the aspartate and alanine aminotraferease activities , serum sodium and potassium ions , and inhibition in blood cholinesterase activity in both erythrocytes and plasma in 2 and 24 houres after injection as compared to the values in animals before injection.

  1. Effect of Addition of Moringa Leaf By-Product (Leaf-Waste) on ...

    African Journals Online (AJOL)

    The effects of incorporation of Moringa leaf fibre (a by-product of leaf processing which contains 24% Crude Fibre by dry weight at 0, 5 and 10 % substitution of wheat flour in cookies was investigated. Three products containing wheat flour: Moringa leaf fibre ratios of 100:0, 95:5, and 90:10 respectively were prepared, and a ...

  2. Interpreting diel hysteresis between soil respiration and temperature

    Science.gov (United States)

    C. Phillips; N. Nickerson; D. Risk; B.J. Bond

    2011-01-01

    Increasing use of automated soil respiration chambers in recent years has demonstrated complex diel relationships between soil respiration and temperature that are not apparent from less frequent measurements. Soil surface flux is often lagged from soil temperature by several hours, which results in semielliptical hysteresis loops when surface flux is plotted as a...

  3. Supporting Aspartate Biosynthesis Is an Essential Function of Respiration in Proliferating Cells.

    Science.gov (United States)

    Sullivan, Lucas B; Gui, Dan Y; Hosios, Aaron M; Bush, Lauren N; Freinkman, Elizaveta; Vander Heiden, Matthew G

    2015-07-30

    Mitochondrial respiration is important for cell proliferation; however, the specific metabolic requirements fulfilled by respiration to support proliferation have not been defined. Here, we show that a major role of respiration in proliferating cells is to provide electron acceptors for aspartate synthesis. This finding is consistent with the observation that cells lacking a functional respiratory chain are auxotrophic for pyruvate, which serves as an exogenous electron acceptor. Further, the pyruvate requirement can be fulfilled with an alternative electron acceptor, alpha-ketobutyrate, which provides cells neither carbon nor ATP. Alpha-ketobutyrate restores proliferation when respiration is inhibited, suggesting that an alternative electron acceptor can substitute for respiration to support proliferation. We find that electron acceptors are limiting for producing aspartate, and supplying aspartate enables proliferation of respiration deficient cells in the absence of exogenous electron acceptors. Together, these data argue a major function of respiration in proliferating cells is to support aspartate synthesis. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Changes in soil respiration after thinning activities in dense Aleppo pine forests

    Science.gov (United States)

    Llovet, Joan; Alonso, Macià; Cerdà, Artemi

    2015-04-01

    Forest fires are a widespread perturbation in Mediterranean areas, and they have tended to increase during the last decades (Pausas, 2004; Moreno et al, 1998). Aleppo pine (Pinus halepensis Mill) is dominant specie in some forest landscapes of western Mediterranean Basin, due to its capacity to colonize abandoned fields, and also due to afforestation practices mainly performed during the 20th century (Ruiz Navarro et al., 2009). Aleppo pine tends to die as consequence of forest fires, although it is able to disperse a high quantity of seeds which easily germinates. These dispersion and germination can result in dense forests with high inter and intra-specific competition, low diversity, low growth, and high fuel accumulation, increasing the risk of new forest fires. These forests of high density present ecological problems and management difficulties that require preventive treatments. Thinning treatments are common in these types of communities, but the management has to be oriented towards strengthening their functions. In the context of global change, better understandings of the implications of forest management practices in the carbon cycle are necessary. The objective of this study was to examine the evolution of seasonal soil respiration after treatment of selective thinning in dense Aleppo pine forests. The study area covers three localities placed in the Valencian Community (E Spain) affected by a forest fire in 1994. Thinning activities were done 16 years after the fire, reducing pine density from around 100,000 individuals per hectare to around 900 individuals per hectare. Soil respiration was measured in situ with a portable soil respiration instrument (LI-6400, LiCor, Lincoln, NB, USA) fitted with a soil respiration chamber (6400-09, LiCor, Lincoln, NB, USA). We installed 12 plots per treatment (control and thinned) and locality, being a total of 72 plots. We carried out 13 measurements covering a period of one year. We also estimated other related

  5. Geochemical importance of isotopic fractionation during respiration

    International Nuclear Information System (INIS)

    Schleser, G.; Foerstel, H.

    1975-01-01

    In 1935 it was found that atmospheric oxygen contained a relatively greater abundance of the 18 O isotope than did the oxygen bound in water (Dole effect). A major contribution to the fractionation of the stable oxygen isotopes should result from the respiration of microorganisms. In this respect our interest centers on the soil because nearly all organic material produced on land is decomposed within the soil. The oceans are less important because the primary productivity on land is twice the value for the oceans. In a first approach we measured the oxygen isotope fractionation during the respiration of E. coli K12 for different respiration rates. These results, accomplished with a chemostat, indicate that the fractionation factor α of the oxygen isotopes increases with the increasing respiratory activity, measured as Q/sub O 2 /. At low dilution rates or growth rates respectively of about 0.05 h -1 , the fractionation factor amounts to 1.006 increasing to 1.017 at dilution rates of about 1.0 h -1 . The results are interpreted as a kinetic mass fractionation due to the slightly different diffusion coefficients of 16 O 2 and 18 O 16 O. The respiration rates in conjunction with the corresponding fractionation data are compared with the respiration rates of typical soil microorganisms such as Azotobacter, in order to deduce fractionation data for these organisms. This is necessary to calculate a mean global fractionation factor. Understanding the Dole effect with these fractionation processes should finally give us the opportunity to calculate gas-exchange rates between the atmosphere and the oceans, on the basis of the behavior of the stable oxygen isotopes

  6. Investigation of the change in marker geometry during respiration motion: a preliminary study for dynamic-multi-leaf real-time tumor tracking

    International Nuclear Information System (INIS)

    Yamazaki, Rie; Nishioka, Seiko; Date, Hiroyuki; Shirato, Hiroki; Koike, Takao; Nishioka, Takeshi

    2012-01-01

    The use of stereotactic body radiotherapy (SBRT) is rapidly increasing. Presently, the most accurate method uses fiducial markers implanted near the tumor. A shortcoming of this method is that the beams turn off during the majority of the respiratory cycle, resulting in a prolonged treatment time. Recent advances in collimation technology have enabled continuous irradiation to a moving tumor. However, the lung is a dynamic organ characterized by inhalation exhalation cycles, during which marker/tumor geometry may change (i.e., misalignment), resulting in under-dosing to the tumor. Eight patients with lung cancer who were candidates for stereotactic radiotherapy were examined with 4D high-resolution CT. As a marker surrogate, virtual bronchoscopy using the pulmonary artery (VBPA) was conducted. To detect possible marker/tumor misalignment during the respiration cycle, the distance between the peripheral bronchus, where a marker could be implanted, and the center of gravity of a tumor were calculated for each respiratory phase. When the respiration cycle was divided into 10 phases, the median value was significantly larger for the 30%-70% respiratory phases compared to that for the 10% respiratory phase (P<0.05, Mann–Whitney U-test). These results demonstrate that physiological aspect must be considered when continuous tumor tracking is applied to a moving tumor. To minimize an “additional” internal target volume (ITV) margin, a marker should be placed approximately 2.5 cm from the tumor

  7. Effect of test exercises and mask donning on measured respirator fit.

    Science.gov (United States)

    Crutchfield, C D; Fairbank, E O; Greenstein, S L

    1999-12-01

    Quantitative respirator fit test protocols are typically defined by a series of fit test exercises. A rationale for the protocols that have been developed is generally not available. There also is little information available that describes the effect or effectiveness of the fit test exercises currently specified in respiratory protection standards. This study was designed to assess the relative impact of fit test exercises and mask donning on respirator fit as measured by a controlled negative pressure and an ambient aerosol fit test system. Multiple donnings of two different sizes of identical respirator models by each of 14 test subjects showed that donning affects respirator fit to a greater degree than fit test exercises. Currently specified fit test protocols emphasize test exercises, and the determination of fit is based on a single mask donning. A rationale for a modified fit test protocol based on fewer, more targeted test exercises and multiple mask donnings is presented. The modified protocol identified inadequately fitting respirators as effectively as the currently specified Occupational Safety and Health Administration (OSHA) quantitative fit test protocol. The controlled negative pressure system measured significantly (p < 0.0001) more respirator leakage than the ambient aerosol fit test system. The bend over fit test exercise was found to be predictive of poor respirator fit by both fit test systems. For the better fitting respirators, only the talking exercise generated aerosol fit factors that were significantly lower (p < 0.0001) than corresponding donning fit factors.

  8. Tai Chi training reduced coupling between respiration and postural control.

    Science.gov (United States)

    Holmes, Matthew L; Manor, Brad; Hsieh, Wan-hsin; Hu, Kun; Lipsitz, Lewis A; Li, Li

    2016-01-01

    In order to maintain stable upright stance, the postural control system must account for the continuous perturbations to the body's center-of-mass including those caused by spontaneous respiration. Both aging and disease increase "posturo-respiratory synchronization;" which reflects the degree to which respiration affects postural sway fluctuations over time. Tai Chi training emphasizes the coordination of respiration and bodily movements and may therefore optimize the functional interaction between these two systems. The purpose of the project was to examine the effect of Tai Chi training on the interaction between respiration and postural control in older adults. We hypothesized that Tai Chi training would improve the ability of the postural control system to compensate for respiratory perturbations and thus, reduce posturo-respiratory synchronization. Participants were recruited from supportive housing facilities and randomized to a 12-week Tai Chi intervention (n=28; 86 ± 5 yrs) or educational-control program (n=34, 85 ± 6 yrs). Standing postural sway and respiration were simultaneously recorded with a force plate and respiratory belt under eyes-open and eyes-closed conditions. Posturo-respiratory synchronization was determined by quantifying the variation of the phase relationship between the dominant oscillatory mode of respiration and corresponding oscillations within postural sway. Groups were similar in age, gender distribution, height, body mass, and intervention compliance. Neither intervention altered average sway speed, sway magnitude or respiratory rate. As compared to the education-control group, however, Tai Chi training reduced posturo-respiratory synchronization when standing with eyes open or closed (ppostural control or respiration, yet reduced the coupling between respiration and postural control. The beneficial effects of Tai Chi training may therefore stem in part from optimization of this multi-system interaction. Copyright © 2015

  9. ECG-derived respiration methods: adapted ICA and PCA.

    Science.gov (United States)

    Tiinanen, Suvi; Noponen, Kai; Tulppo, Mikko; Kiviniemi, Antti; Seppänen, Tapio

    2015-05-01

    Respiration is an important signal in early diagnostics, prediction, and treatment of several diseases. Moreover, a growing trend toward ambulatory measurements outside laboratory environments encourages developing indirect measurement methods such as ECG derived respiration (EDR). Recently, decomposition techniques like principal component analysis (PCA), and its nonlinear version, kernel PCA (KPCA), have been used to derive a surrogate respiration signal from single-channel ECG. In this paper, we propose an adapted independent component analysis (AICA) algorithm to obtain EDR signal, and extend the normal linear PCA technique based on the best principal component (PC) selection (APCA, adapted PCA) to improve its performance further. We also demonstrate that the usage of smoothing spline resampling and bandpass-filtering improve the performance of all EDR methods. Compared with other recent EDR methods using correlation coefficient and magnitude squared coherence, the proposed AICA and APCA yield a statistically significant improvement with correlations 0.84, 0.82, 0.76 and coherences 0.90, 0.91, 0.85 between reference respiration and AICA, APCA and KPCA, respectively. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

  10. Renal mobility during uncoached quiet respiration: An analysis of 4DCT scans

    International Nuclear Information System (INIS)

    Soernsen de Koste, John R. van; Senan, Suresh; Kleynen, Catharina E.; Slotman, Ben J.; Lagerwaard, Frank J.

    2006-01-01

    Purpose: Data on organ mobility is required for optimizing radiotherapy. Renal mobility was studied in four-dimensional computed tomography (4DCT) scans acquired during uncoached respiration. Methods and Materials: The 4DCT scans of 54 patients, in whom at least the upper pole of both kidneys were visualized in all 10 respiratory phases, were analyzed. Scans were performed on a 16-slice CT scanner (slice index and reconstruction, 2.5 mm) during quiet, uncoached respiration. Mobility of the renal apex was evaluated in all patients by use of the z-position on CT slices. Reproducibility of mobility was studied in 8 patients who underwent 1 or 2 repeat 4DCT scans. Results: Mobility was predominantly craniocaudal, with a mean of 9.8 mm for the left kidney and 9.0 mm for the right kidney. Large interpatient variations were observed that ranged from 2.5 to 30 mm (left) and 2.5 to 20 mm (right), and mobility of 1 kidney did not predict for mobility of the contralateral organ. Reproducibility of renal mobility and position at end-expiration was poor, with positional variations in repeat scans appearing to correlate with changes in the amplitude of respiratory waveform and total lung volume. Conclusions: Large interpatient variations in renal movement occur during uncoached respiration, which indicates that respiratory coaching is useful for 4DCT imaging and treatment delivery

  11. Effect of nitrogen supply on leaf appearance, leaf growth, leaf nitrogen economy and photosynthetic capacity in maize (Zea mays L.)

    NARCIS (Netherlands)

    Vos, J.; Putten, van der P.E.L.; Birch, C.J.

    2005-01-01

    Leaf area growth and nitrogen concentration per unit leaf area, Na (g m-2 N) are two options plants can use to adapt to nitrogen limitation. Previous work indicated that potato (Solanum tuberosum L.) adapts the size of leaves to maintain Na and photosynthetic capacity per unit leaf area. This paper

  12. Differential soil respiration responses to changing hydrologic regimes

    Science.gov (United States)

    Vincent J. Pacific; Brian L. McGlynn; Diego A. Riveros-Iregui; Howard E. Epstein; Daniel L. Welsch

    2009-01-01

    Soil respiration is tightly coupled to the hydrologic cycle (i.e., snowmelt and precipitation timing and magnitude). We examined riparian and hillslope soil respiration across a wet (2005) and a dry (2006) growing season in a subalpine catchment. When comparing the riparian zones, cumulative CO2 efflux was 33% higher, and peak efflux occurred 17 days earlier during the...

  13. Respirator studies for the Nuclear Regulatory Commission. Protection factors for supplied-air respirators. Progress report, October 1, 1976--September 30, 1977

    International Nuclear Information System (INIS)

    Hack, A.; Bradley, O.D.; Trujillo, A.

    1977-12-01

    This report describes the work performed during FY 1977 for the Nuclear Regulatory Commission. The Protection Factors (efficiency) provided by 25 NIOSH approved supplied-air respirators were determined while the devices were worn by a panel of anthropometrically selected test subjects. The major recommendation was that demand-type respirators should neither be used nor approved

  14. Two Proximal Skin Electrodes — A Respiration Rate Body Sensor

    Directory of Open Access Journals (Sweden)

    Viktor Avbelj

    2012-10-01

    Full Text Available We propose a new body sensor for extracting the respiration rate based on the amplitude changes in the body surface potential differences between two proximal body electrodes. The sensor could be designed as a plaster-like reusable unit that can be easily fixed onto the surface of the body. It could be equipped either with a sufficiently large memory for storing the measured data or with a low-power radio system that can transmit the measured data to a gateway for further processing. We explore the influence of the sensor’s position on the quality of the extracted results using multi-channel ECG measurements and considering all the pairs of two neighboring electrodes as potential respiration-rate sensors. The analysis of the clinical measurements, which also include reference thermistor-based respiration signals, shows that the proposed approach is a viable option for monitoring the respiration frequency and for a rough classification of breathing types. The obtained results were evaluated on a wireless prototype of a respiration body sensor. We indicate the best positions for the respiration body sensor and prove that a single sensor for body surface potential difference on proximal skin electrodes can be used for combined measurements of respiratory and cardiac activities.

  15. Targeting mitochondrial respiration as a therapeutic strategy for cervical cancer.

    Science.gov (United States)

    Tian, Shenglan; Chen, Heng; Tan, Wei

    2018-05-23

    Targeting mitochondrial respiration has been documented as an effective therapeutic strategy in cancer. However, the impact of mitochondrial respiration inhibition on cervical cancer cells are not well elucidated. Using a panel of cervical cancer cell lines, we show that an existing drug atovaquone is active against the cervical cancer cells with high profiling of mitochondrial biogenesis. Atovaquone inhibited proliferation and induced apoptosis with varying efficacy among cervical cancer cell lines regardless of HPV infection, cellular origin and their sensitivity to paclitaxel. We further demonstrated that atovaquone acts on cervical cancer cells via inhibiting mitochondrial respiration. In particular, atovaquone specifically inhibited mitochondrial complex III but not I, II or IV activity, leading to respiration inhibition and energy crisis. Importantly, we found that the different sensitivity of cervical cancer cell lines to atovaquone were due to their differential level of mitochondrial biogenesis and dependency to mitochondrial respiration. In addition, we demonstrated that the in vitro observations were translatable to in vivo cervical cancer xenograft mouse model. Our findings suggest that the mitochondrial biogenesis varies among patients with cervical cancer. Our work also suggests that atovaquone is a useful addition to cervical cancer treatment, particularly to those with high dependency on mitochondrial respiration. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. SU-F-T-350: Continuous Leaf Optimization (CLO) for IMRT Leaf Sequencing

    Energy Technology Data Exchange (ETDEWEB)

    Long, T; Chen, M; Jiang, S; Lu, W [UT Southwestern Medical Center, Dallas, TX (United States)

    2016-06-15

    Purpose: To study a new step-and-shoot IMRT leaf sequencing model that avoids the two main pitfalls of conventional leaf sequencing: (1) target fluence being stratified into a fixed number of discrete levels and/or (2) aperture leaf positions being restricted to a discrete set of locations. These assumptions induce error into the sequence or reduce the feasible region of potential plans, respectively. Methods: We develop a one-dimensional (single leaf pair) methodology that does not make assumptions (1) or (2) that can be easily extended to a multi-row model. The proposed continuous leaf optimization (CLO) methodology takes in an existing set of apertures and associated intensities, or solution “seed,” and improves the plan without the restrictiveness of 1or (2). It then uses a first-order descent algorithm to converge onto a locally optimal solution. A seed solution can come from models that assume (1) and (2), thus allowing the CLO model to improve upon existing leaf sequencing methodologies. Results: The CLO model was applied to 208 generated target fluence maps in one dimension. In all cases for all tested sequencing strategies, the CLO model made improvements on the starting seed objective function. The CLO model also was able to keep MUs low. Conclusion: The CLO model can improve upon existing leaf sequencing methods by avoiding the restrictions of (1) and (2). By allowing for more flexible leaf positioning, error can be reduced when matching some target fluence. This study lays the foundation for future models and solution methodologies that can incorporate continuous leaf positions explicitly into the IMRT treatment planning model. Supported by Cancer Prevention & Research Institute of Texas (CPRIT) - ID RP150485.

  17. Measurement of lung tumor motion using respiration-correlated CT

    International Nuclear Information System (INIS)

    Mageras, Gig S.; Pevsner, Alex; Yorke, Ellen D.; Rosenzweig, Kenneth E.; Ford, Eric C.; Hertanto, Agung; Larson, Steven M.; Lovelock, D. Michael; Erdi, Yusuf E.; Nehmeh, Sadek A.; Humm, John L.; Ling, C. Clifton

    2004-01-01

    Purpose: We investigate the characteristics of lung tumor motion measured with respiration-correlated computed tomography (RCCT) and examine the method's applicability to radiotherapy planning and treatment. Methods and materials: Six patients treated for non-small-cell lung carcinoma received a helical single-slice computed tomography (CT) scan with a slow couch movement (1 mm/s), while simultaneously respiration is recorded with an external position-sensitive monitor. Another 6 patients receive a 4-slice CT scan in a cine mode, in which sequential images are acquired for a complete respiratory cycle at each couch position while respiration is recorded. The images are retrospectively resorted into different respiration phases as measured with the external monitor (4-slice data) or patient surface displacement observed in the images (single-slice data). The gross tumor volume (GTV) in lung is delineated at one phase and serves as a visual guide for delineation at other phases. Interfractional GTV variation is estimated by scaling diaphragm position variations measured in gated radiographs at treatment with the ratio of GTV:diaphragm displacement observed in the RCCT data. Results: Seven out of 12 patients show GTV displacement with respiration of more than 1 cm, primarily in the superior-inferior (SI) direction; 2 patients show anterior-posterior displacement of more than 1 cm. In all cases, extremes in GTV position in the SI direction are consistent with externally measured extremes in respiration. Three patients show evidence of hysteresis in GTV motion, in which the tumor trajectory is displaced 0.2 to 0.5 cm anteriorly during expiration relative to inspiration. Significant (>1 cm) expansion of the GTV in the SI direction with respiration is observed in 1 patient. Estimated intrafractional GTV motion for gated treatment at end expiration is 0.6 cm or less in all cases; however; interfraction variation estimates (systematic plus random) are more than 1 cm in 3

  18. Evaluation of banana hybrids for tolerance to black leaf streak (Mycosphaerella fijiensis Morelet) in Puerto Rico

    Science.gov (United States)

    In Puerto Rico, bananas (including plantains) are important agricultural commodities; their combined production totaled 133,500 tons in 2008. Black leaf streak (BLS) and Sigatoka leaf spot diseases, caused by Mycosphaerella fijiensis and M. musicola, respectively, are responsible for significant los...

  19. Identification of Alfalfa Leaf Diseases Using Image Recognition Technology.

    Directory of Open Access Journals (Sweden)

    Feng Qin

    Full Text Available Common leaf spot (caused by Pseudopeziza medicaginis, rust (caused by Uromyces striatus, Leptosphaerulina leaf spot (caused by Leptosphaerulina briosiana and Cercospora leaf spot (caused by Cercospora medicaginis are the four common types of alfalfa leaf diseases. Timely and accurate diagnoses of these diseases are critical for disease management, alfalfa quality control and the healthy development of the alfalfa industry. In this study, the identification and diagnosis of the four types of alfalfa leaf diseases were investigated using pattern recognition algorithms based on image-processing technology. A sub-image with one or multiple typical lesions was obtained by artificial cutting from each acquired digital disease image. Then the sub-images were segmented using twelve lesion segmentation methods integrated with clustering algorithms (including K_means clustering, fuzzy C-means clustering and K_median clustering and supervised classification algorithms (including logistic regression analysis, Naive Bayes algorithm, classification and regression tree, and linear discriminant analysis. After a comprehensive comparison, the segmentation method integrating the K_median clustering algorithm and linear discriminant analysis was chosen to obtain lesion images. After the lesion segmentation using this method, a total of 129 texture, color and shape features were extracted from the lesion images. Based on the features selected using three methods (ReliefF, 1R and correlation-based feature selection, disease recognition models were built using three supervised learning methods, including the random forest, support vector machine (SVM and K-nearest neighbor methods. A comparison of the recognition results of the models was conducted. The results showed that when the ReliefF method was used for feature selection, the SVM model built with the most important 45 features (selected from a total of 129 features was the optimal model. For this SVM model, the

  20. Identification of Alfalfa Leaf Diseases Using Image Recognition Technology

    Science.gov (United States)

    Qin, Feng; Liu, Dongxia; Sun, Bingda; Ruan, Liu; Ma, Zhanhong; Wang, Haiguang

    2016-01-01

    Common leaf spot (caused by Pseudopeziza medicaginis), rust (caused by Uromyces striatus), Leptosphaerulina leaf spot (caused by Leptosphaerulina briosiana) and Cercospora leaf spot (caused by Cercospora medicaginis) are the four common types of alfalfa leaf diseases. Timely and accurate diagnoses of these diseases are critical for disease management, alfalfa quality control and the healthy development of the alfalfa industry. In this study, the identification and diagnosis of the four types of alfalfa leaf diseases were investigated using pattern recognition algorithms based on image-processing technology. A sub-image with one or multiple typical lesions was obtained by artificial cutting from each acquired digital disease image. Then the sub-images were segmented using twelve lesion segmentation methods integrated with clustering algorithms (including K_means clustering, fuzzy C-means clustering and K_median clustering) and supervised classification algorithms (including logistic regression analysis, Naive Bayes algorithm, classification and regression tree, and linear discriminant analysis). After a comprehensive comparison, the segmentation method integrating the K_median clustering algorithm and linear discriminant analysis was chosen to obtain lesion images. After the lesion segmentation using this method, a total of 129 texture, color and shape features were extracted from the lesion images. Based on the features selected using three methods (ReliefF, 1R and correlation-based feature selection), disease recognition models were built using three supervised learning methods, including the random forest, support vector machine (SVM) and K-nearest neighbor methods. A comparison of the recognition results of the models was conducted. The results showed that when the ReliefF method was used for feature selection, the SVM model built with the most important 45 features (selected from a total of 129 features) was the optimal model. For this SVM model, the

  1. Glycolysis Is Dynamic and Relates Closely to Respiration Rate in Stored Sugarbeet Roots

    Directory of Open Access Journals (Sweden)

    Clarice A. Megguer

    2017-05-01

    Full Text Available Although respiration is the principal cause of the loss of sucrose in postharvest sugarbeet (Beta vulgaris L., the internal mechanisms that control root respiration rate are unknown. Available evidence, however, indicates that respiration rate is likely to be controlled by the availability of respiratory substrates, and glycolysis has a central role in generating these substrates. To determine glycolytic changes that occur in sugarbeet roots after harvest and to elucidate relationships between glycolysis and respiration, sugarbeet roots were stored for up to 60 days, during which activities of glycolytic enzymes and concentrations of glycolytic substrates, intermediates, cofactors, and products were determined. Respiration rate was also determined, and relationships between respiration rate and glycolytic enzymes and metabolites were evaluated. Glycolysis was highly variable during storage, with 10 of 14 glycolytic activities and 14 of 17 glycolytic metabolites significantly altered during storage. Changes in glycolytic enzyme activities and metabolites occurred throughout the 60 day storage period, but were greatest in the first 4 days after harvest. Positive relationships between changes in glycolytic enzyme activities and root respiration rate were abundant, with 10 of 14 enzyme activities elevated when root respiration was elevated and 9 glycolytic activities static during periods of unchanging respiration rate. Major roles for pyruvate kinase and phosphofructokinase in the regulation of postharvest sugarbeet root glycolysis were indicated based on changes in enzymatic activities and concentrations of their substrates and products. Additionally, a strong positive relationship between respiration rate and pyruvate kinase activity was found indicating that downstream TCA cycle enzymes were unlikely to regulate or restrict root respiration in a major way. Overall, these results establish that glycolysis is not static during sugarbeet root

  2. Antimicrobial compounds from leaf extracts of Jatropha curcas, Psidium guajava, and Andrographis paniculata.

    Science.gov (United States)

    Rahman, M M; Ahmad, S H; Mohamed, M T M; Ab Rahman, M Z

    2014-01-01

    The present research was conducted to discover antimicrobial compounds in methanolic leaf extracts of Jatropha curcas and Andrographis paniculata and ethanolic leaf extract of Psidium guajava and the effectiveness against microbes on flower preservative solution of cut Mokara Red orchid flowers was evaluated. The leaves were analyzed using gas chromatography-mass spectrometry. A total of nine, 66, and 29 compounds were identified in J. curcas, P. guajava, and A. paniculata leaf extracts, with five (88.18%), four (34.66%), and three (50.47%) having unique antimicrobial compounds, respectively. The experimental design on vase life was conducted using a completely randomized design with 10 replications. The flower vase life was about 6 days in the solution containing the P. guajava and A. paniculata leaf extracts at 15 mg/L. Moreover, solution with leaf extracts of A. paniculata had the lowest bacterial count compared to P. guajava and J. curcas. Thus, these leaf extracts revealed the presence of relevant antimicrobial compounds. The leaf extracts have the potential as a cut flower solution to minimize microbial populations and extend flower vase life. However, the activities of specific antimicrobial compounds and double or triple combination leaf extracts to enhance the effectiveness to extend the vase life need to be tested.

  3. Influence of forced respiration on nonlinear dynamics in heart rate variability

    DEFF Research Database (Denmark)

    Kanters, J K; Højgaard, M V; Agner, E

    1997-01-01

    Although it is doubtful whether the normal sinus rhythm can be described as low-dimensional chaos, there is evidence for inherent nonlinear dynamics and determinism in time series of consecutive R-R intervals. However, the physiological origin for these nonlinearities is unknown. The aim...... with a metronome set to 12 min(-1). Nonlinear dynamics were measured as the correlation dimension and the nonlinear prediction error. Complexity expressed as correlation dimension was unchanged from normal respiration, 9.1 +/- 0.5, compared with forced respiration, 9.3 +/- 0.6. Also, nonlinear determinism...... expressed as the nonlinear prediction error did not differ between spontaneous respiration, 32.3 +/- 3.4 ms, and forced respiration, 31.9 +/- 5.7. It is concluded that the origin of the nonlinear dynamics in heart rate variability is not a nonlinear input from the respiration into the cardiovascular...

  4. Photosynthate partitioning in basal zones of tall fescue leaf blades

    International Nuclear Information System (INIS)

    Allard, G.; Nelson, C.J.

    1991-01-01

    Elongating grass leaves have successive zones of cell division, cell elongation, and cell maturation in the basal portion of the blade and are a strong sink for photosynthate. Our objective was to determine dry matter (DM) deposition and partitioning in basal zones of elongating tall fescue (Festuca arundinacea Schreb.) leaf blades. Vegetative tall fescue plants were grown in continuous light (350 micromoles per square meter per second photosynthetic photon flux density) to obtain a constant spatial distribution of elongation growth with time. Content and net deposition rates of water-soluble carbohydrates (WSC) and DM along elongating leaf blades were determined. These data were compared with accumulation of 14 C in the basal zones following leaf-labeling with 14 CO 2 . Net deposition of DM was highest in the active cell elongation zone, due mainly to deposition of WSC. The maturation zone, just distal to the elongation zone, accounted for 22% of total net deposition of DM in elongating leaves. However, the spatial profile of 14 C accumulation suggested that the elongation zone and the maturation zone were sinks of equal strength. WSC-free DM accounted for 55% of the total net DM deposition in elongating leaf blades, but only 10% of incoming 14 C-photosynthate accumulated in the water-insoluble fraction (WIF ∼ WSC-free DM) after 2 hours. In the maturation zone, more WSC was used for synthesis of WSC-free DM than was imported as recent photosynthate

  5. Effect of Wind on the Relation of Leaf N, P Stoichiometry with Leaf Morphology in Quercus Species

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2018-02-01

    Full Text Available Leaf nitrogen (N and phosphorus (P stoichiometry correlates closely to leaf morphology, which is strongly impacted by wind at multiple scales. However, it is not clear how leaf N, P stoichiometry and its relationship to leaf morphology changes with wind load. We determined the leaf N and P concentrations and leaf morphology—including specific leaf area (SLA and leaf dissection index (LDI—for eight Quercus species under a simulated wind load for seven months. Leaf N and P concentrations increased significantly under these conditions for Quercus acutissima, Quercus rubra, Quercus texana, and Quercus palustris—which have elliptic leaves—due to their higher N, P requirements and a resultant leaf biomass decrease, which is a tolerance strategy for Quercus species under a wind load. Leaf N:P was relatively stable under wind for all species, which supports stoichiometric homeostasis. Leaf N concentrations showed a positive correlation to SLA, leaf N and P concentrations showed positive correlations to LDI under each wind treatment, and the slope of correlations was not affected by wind, which indicates synchronous variations between leaf stoichiometry and leaf morphology under wind. However, the intercept of correlations was affected by wind, and leaf N and P use efficiency decreased under the wind load, which suggests that the Quercus species changes from “fast investment-return” in the control to “slow investment-return” under windy conditions. These results will be valuable to understanding functional strategies for plants under varying wind loads, especially synchronous variations in leaf traits along a wind gradient.

  6. Response Surface Optimized Extraction of Total Triterpene Acids ...

    African Journals Online (AJOL)

    Purpose: To optimize extraction of total triterpene acids from loquat leaf and evaluate their in vitro antioxidant activities. Methods: The independent variables were ethanol concentration, extraction time, and solvent ratio, while the dependent variable was content of total triterpene acids. Composite design and response ...

  7. Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species?

    Directory of Open Access Journals (Sweden)

    BRUNO H.P. ROSADO

    2013-09-01

    Full Text Available During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models.

  8. Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species?

    Science.gov (United States)

    Rosado, Bruno H P; De Mattos, Eduardo A; Sternberg, Leonel Da S L

    2013-09-01

    During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models.

  9. Effects of bioirrigation of non-biting midges (Diptera: Chironomidae) on lake sediment respiration

    Science.gov (United States)

    Baranov, Viktor; Lewandowski, Jörg; Romeijn, Paul; Singer, Gabriel; Krause, Stefan

    2016-06-01

    Bioirrigation or the transport of fluids into the sediment matrix due to the activities of organisms such as bloodworms (larvae of Diptera, Chironomidae), has substantial impacts on sediment respiration in lakes. However, previous quantifications of bioirrigation impacts of Chironomidae have been limited by technical challenges such as the difficulty to separate faunal and bacterial respiration. This paper describes a novel method based on the bioreactive tracer resazurin for measuring respiration in-situ in non-sealed systems with constant oxygen supply. Applying this new method in microcosm experiments revealed that bioirrigation enhanced sediment respiration by up to 2.5 times. The new method is yielding lower oxygen consumption than previously reported, as it is only sensitive to aerobic heterotrophous respiration and not to other processes causing oxygen decrease. Hence it decouples the quantification of respiration of animals and inorganic oxygen consumption from microbe respiration in sediment.

  10. Automatic patient respiration failure detection system with wireless transmission

    Science.gov (United States)

    Dimeff, J.; Pope, J. M.

    1968-01-01

    Automatic respiration failure detection system detects respiration failure in patients with a surgically implanted tracheostomy tube, and actuates an audible and/or visual alarm. The system incorporates a miniature radio transmitter so that the patient is unencumbered by wires yet can be monitored from a remote location.

  11. Tuning Transpiration by Interfacial Solar Absorber-Leaf Engineering.

    Science.gov (United States)

    Zhuang, Shendong; Zhou, Lin; Xu, Weichao; Xu, Ning; Hu, Xiaozhen; Li, Xiuqiang; Lv, Guangxin; Zheng, Qinghui; Zhu, Shining; Wang, Zhenlin; Zhu, Jia

    2018-02-01

    Plant transpiration, a process of water movement through a plant and its evaporation from aerial parts especially leaves, consumes a large component of the total continental precipitation (≈48%) and significantly influences global water distribution and climate. To date, various chemical and/or biological explorations have been made to tune the transpiration but with uncertain environmental risks. In recent years, interfacial solar steam/vapor generation is attracting a lot of attention for achieving high energy transfer efficiency. Various optical and thermal designs at the solar absorber-water interface for potential applications in water purification, seawater desalination, and power generation appear. In this work, the concept of interfacial solar vapor generation is extended to tunable plant transpiration by showing for the first time that the transpiration efficiency can also be enhanced or suppressed through engineering the solar absorber-leaf interface. By tuning the solar absorption of membrane in direct touch with green leaf, surface temperature of green leaf will change accordingly because of photothermal effect, thus the transpiration efficiency as well as temperature and relative humidity in the surrounding environment will be tuned. This tunable transpiration by interfacial absorber-leaf engineering can open an alternative avenue to regulate local atmospheric temperature, humidity, and eventually hydrologic cycle.

  12. Tuning Transpiration by Interfacial Solar Absorber‐Leaf Engineering

    Science.gov (United States)

    Zhuang, Shendong; Zhou, Lin; Xu, Weichao; Xu, Ning; Hu, Xiaozhen; Li, Xiuqiang; Lv, Guangxin; Zheng, Qinghui; Zhu, Shining

    2017-01-01

    Abstract Plant transpiration, a process of water movement through a plant and its evaporation from aerial parts especially leaves, consumes a large component of the total continental precipitation (≈48%) and significantly influences global water distribution and climate. To date, various chemical and/or biological explorations have been made to tune the transpiration but with uncertain environmental risks. In recent years, interfacial solar steam/vapor generation is attracting a lot of attention for achieving high energy transfer efficiency. Various optical and thermal designs at the solar absorber–water interface for potential applications in water purification, seawater desalination, and power generation appear. In this work, the concept of interfacial solar vapor generation is extended to tunable plant transpiration by showing for the first time that the transpiration efficiency can also be enhanced or suppressed through engineering the solar absorber–leaf interface. By tuning the solar absorption of membrane in direct touch with green leaf, surface temperature of green leaf will change accordingly because of photothermal effect, thus the transpiration efficiency as well as temperature and relative humidity in the surrounding environment will be tuned. This tunable transpiration by interfacial absorber‐leaf engineering can open an alternative avenue to regulate local atmospheric temperature, humidity, and eventually hydrologic cycle. PMID:29619300

  13. Redefinition and global estimation of basal ecosystem respiration rate

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Wenping [College of Global Change and Earth System Science, Beijing Normal University, Beijing, China; Luo, Yiqi [Department of Botany and Microbiology, University of Oklahoma, Norman, Oklahoma, USA; Li, Xianglan [College of Global Change and Earth System Science, Beijing Normal University, Beijing, China; Liu, Shuguang; Yu, Guirui [Key Laboratory of Ecosystem Network Observation and Modeling, Synthesis Research Center of Chinese Ecosystem Research Network, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China; Zhou, Tao [State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China; Bahn, Michael [Institute of Ecology, University of Innsbruck, Innsbruck, Austria; Black, Andy [Faculty of Land and Food Systems, University of British Columbia, Vancouver, B. C., Canada; Desai, Ankur R. [Atmospheric and Oceanic Sciences Department, Center for Climatic Research, Nelson Institute for Environmental Studies, University of Wisconsin-Madison, Madison, Wisconsin, USA; Cescatti, Alessandro [Institute for Environment and Sustainability, Joint Research Centre, European Commission, Ispra, Italy; Marcolla, Barbara [Sustainable Agro-ecosystems and Bioresources Department, Fondazione Edmund Mach-IASMA Research and Innovation Centre, San Michele all' Adige, Italy; Jacobs, Cor [Alterra, Earth System Science-Climate Change, Wageningen University, Wageningen, Netherlands; Chen, Jiquan [Department of Earth, Ecological, and Environmental Sciences, University of Toledo, Toledo, Ohio, USA; Aurela, Mika [Climate and Global Change Research, Finnish Meteorological Institute, Helsinki, Finland; Bernhofer, Christian [Chair of Meteorology, Institute of Hydrology and Meteorology, Technische Universität Dresden, Dresden, Germany; Gielen, Bert [Department of Biology, University of Antwerp, Wilrijk, Belgium; Bohrer, Gil [Department of Civil, Environmental, and Geodetic Engineering, Ohio State University, Columbus, Ohio, USA; Cook, David R. [Climate Research Section, Environmental Science Division, Argonne National Laboratory, Argonne, Illinois, USA; Dragoni, Danilo [Department of Geography, Indiana University, Bloomington, Indiana, USA; Dunn, Allison L. [Department of Physical and Earth Sciences, Worcester State College, Worcester, Massachusetts, USA; Gianelle, Damiano [Sustainable Agro-ecosystems and Bioresources Department, Fondazione Edmund Mach-IASMA Research and Innovation Centre, San Michele all' Adige, Italy; Grünwald, Thomas [Chair of Meteorology, Institute of Hydrology and Meteorology, Technische Universität Dresden, Dresden, Germany; Ibrom, Andreas [Risø DTU National Laboratory for Sustainable Energy, Biosystems Division, Technical University of Denmark, Roskilde, Denmark; Leclerc, Monique Y. [Department of Crop and Soil Sciences, College of Agricultural and Environmental Sciences, University of Georgia, Griffin, Georgia, USA; Lindroth, Anders [Geobiosphere Science Centre, Physical Geography and Ecosystems Analysis, Lund University, Lund, Sweden; Liu, Heping [Laboratory for Atmospheric Research, Department of Civil and Environmental Engineering, Washington State University, Pullman, Washington, USA; Marchesini, Luca Belelli [Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, Viterbo, Italy; Montagnani, Leonardo; Pita, Gabriel [Department of Mechanical Engineering, Instituto Superior Técnico, Lisbon, Portugal; Rodeghiero, Mirco [Sustainable Agro-ecosystems and Bioresources Department, Fondazione Edmund Mach-IASMA Research and Innovation Centre, San Michele all' Adige, Italy; Rodrigues, Abel [Unidade de Silvicultura e Produtos Florestais, Instituto Nacional dos Recursos Biológicos, Oeiras, Portugal; Starr, Gregory [Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA; Stoy, Paul C. [Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, Montana, USA

    2011-10-13

    Basal ecosystem respiration rate (BR), the ecosystem respiration rate at a given temperature, is a common and important parameter in empirical models for quantifying ecosystem respiration (ER) globally. Numerous studies have indicated that BR varies in space. However, many empirical ER models still use a global constant BR largely due to the lack of a functional description for BR. In this study, we redefined BR to be ecosystem respiration rate at the mean annual temperature. To test the validity of this concept, we conducted a synthesis analysis using 276 site-years of eddy covariance data, from 79 research sites located at latitudes ranging from ~3°S to ~70°N. Results showed that mean annual ER rate closely matches ER rate at mean annual temperature. Incorporation of site-specific BR into global ER model substantially improved simulated ER compared to an invariant BR at all sites. These results confirm that ER at the mean annual

  14. Disclosure and Fit Capability of the Filtering Facepiece Respirator.

    Science.gov (United States)

    Lofgren, Don J

    2018-05-01

    The filtering facepiece air-purifying respirator is annually purchased in the tens of millions and widely used for worker protection from harmful airborne particulates. The workplace consumers of this safety product, i.e., employers, workers, and safety and health professionals, have assurances of its effectiveness through the respirator certification and disclosure requirements of the National Institute for Occupational Safety and Health. However, the certification of a critical performance requirement has been missing for the approved filtering facepiece respirator since 1995: fit capability. Without this certification, consumers continue to be at risk of purchasing a respirator model that may fit a small percentage of the intended users. This commentary updates and expands an earlier one by this author, addresses the consequences of poorly fitting certified models on the market and lack of disclosure, and calls for further action by National Institute for Occupational Safety and Health to meet the needs and expectations of the consumer.

  15. Ascorbate Biosynthesis in Mitochondria Is Linked to the Electron Transport Chain between Complexes III and IV1

    Science.gov (United States)

    Bartoli, Carlos G.; Pastori, Gabriela M.; Foyer, Christine H.

    2000-01-01

    Ascorbic acid is synthesized from galactono-γ-lactone (GL) in plant tissues. An improved extraction procedure involving ammonium sulfate precipitation of membrane proteins from crude leaf homogenates yielded a simple, quick method for determining tissue activities of galactono-γ-lactone dehydrogenase (GLDH). Total foliar ascorbate and GLDH activity decreased with leaf age. Subcellular fractionation experiments using marker enzymes demonstrated that 80% of the total GLDH activity was located on the inner mitochondrial membrane, and 20% in the microsomal fraction. Specific antibody raised against potato (Solanum tuberosum L.) tuber GLDH recognized a 56-kD polypeptide in extracts from the mitochondrial membranes but failed to detect the equivalent polypeptide in microsomes. We demonstrate that isolated intact mitochondria synthesize ascorbate in the presence of GL. GL stimulated mitochondrial electron transport rates. The respiration inhibitor antimycin A stimulated ascorbate biosynthesis, while cyanide inhibited both respiration and ascorbate production. GL-dependent oxygen uptake was observed in isolated intact mitochondria. This evidence suggests that GLDH delivers electrons to the mitochondrial electron transport chain between complexes III and IV. PMID:10806250

  16. Untangling metabolic and spatial interactions of stress tolerance in plants. 2. Accelerated method for measuring and predicting stress tolerance. Can we unravel the mysteries of the interactions between photosynthesis and respiration?

    Science.gov (United States)

    Biel, Karl Y; Nishio, John N

    2010-09-01

    A simple method using the O(2) electrode that allows examination of the response of respiration and photosynthesis in leaf slices or algae to anoxia and high light under different temperatures useful for the examination of the interactions among photosynthesis, photorespiration, and respiration is described. The method provides a quantifiable assessment of stress tolerance that also permits us to examine fundamental biochemically and genetically related responses involved in stress tolerance and the cooperation among organelles. Additionally, we demonstrated a role for compounds, such as NO(-)(3) and oxaloacetate, as protective agents against photoinhibition, and we examined the role of dark adaptation in the activation of photosynthesis and NO(-)(3)-dependent O(2) oxygen evolution. A physiological and ecological role of a dark period (night) in stress tolerance is presented. Utilizing the method to follow changes in such metabolic activities as protein synthesis, protein conformation states, enzymes activity, carbon metabolism, and gene expression at different points during the treatments will be educational.

  17. Creating the Chemistry in Cellular Respiration Concept Inventory (CCRCI)

    Science.gov (United States)

    Forshee, Jay Lance, II

    Students at our institution report cellular respiration to be the most difficult concept they encounter in undergraduate biology, but why students find this difficult is unknown. Students may find cellular respiration difficult because there is a large amount of steps, or because there are persistent, long-lasting misconceptions and misunderstandings surrounding their knowledge of chemistry, which affect their performance on cellular respiration assessments. Most studies of cellular respiration focus on student macro understanding of the process related to breathing, and matter and energy. To date, no studies identify which chemistry concepts are most relevant to students' development of an understanding of the process of cellular respiration or have developed an assessment to measure student understanding of them. Following the Delphi method, the researchers conducted expert interviews with faculty members from four-year, masters-, and PhD-granting institutions who teach undergraduate general biology, and are experts in their respective fields of biology. From these interviews, researchers identified twelve chemistry concepts important to understanding cellular respiration and using surveys, these twelve concepts were refined into five (electron transfer, energy transfer, thermodynamics (law/conservation), chemical reactions, and gradients). The researchers then interviewed undergraduate introductory biology students at a large Midwestern university to identify their knowledge and misconceptions of the chemistry concepts that the faculty had identified previously as important. The CCRCI was developed using the five important chemistry concepts underlying cellular respiration. The final version of the CCRCI was administered to n=160 introductory biology students during the spring 2017 semester. Reliability of the CCRCI was evaluated using Cronbach's alpha (=.7) and split-half reliability (=.769), and validity of the instrument was assessed through content validity

  18. An evolutionary perspective on leaf economics : Phylogenetics of leaf mass per area in vascular plants

    NARCIS (Netherlands)

    Flores, Olivier; Garnier, Eric; Wright, Ian J.; Reich, Peter B.; Pierce, Simon; Diaz, Sandra; Pakeman, Robin J.; Rusch, Graciela M.; Bernard-Verdier, Maud; Testi, Baptiste; Bakker, Jan P.; Bekker, Renee M.; Cerabolini, Bruno E. L.; Ceriani, Roberta M.; Cornu, Guillaume; Cruz, Pablo; Delcamp, Matthieu; Dolezal, Jiri; Eriksson, Ove; Fayolle, Adeline; Freitas, Helena; Golodets, Carly; Gourlet-Fleury, Sylvie; Hodgson, John G.; Brusa, Guido; Kleyer, Michael; Kunzmann, Dieter; Lavorel, Sandra; Papanastasis, Vasilios P.; Perez-Harguindeguy, Natalia; Vendramini, Fernanda; Weiher, Evan

    In plant leaves, resource use follows a trade-off between rapid resource capture and conservative storage. This "worldwide leaf economics spectrum" consists of a suite of intercorrelated leaf traits, among which leaf mass per area, LMA, is one of the most fundamental as it indicates the cost of leaf

  19. Contribution of root respiration to soil respiration in a C3/C4 mixed ...

    Indian Academy of Sciences (India)

    Unknown

    The linear regression relationship between soil respiration and root biomass was used to determine the .... 10 days, sieved 50 g soil samples were placed in a 100 ml beaker and a 250 ..... Comparatively, the method can take multi-samples by ...

  20. Spectroscopic determination of leaf water content using linear ...

    African Journals Online (AJOL)

    DR. NJ TONUKARI

    2012-02-02

    Feb 2, 2012 ... characteristics, this study measured 33 groups of peach tree leaf ... spectral absorption values were obtained from a total of 33 groups of leaves .... using the trial and error method, based on the following empirical ... be used as indicators for evaluation of prediction models. .... Comparison of the methods of.

  1. Procedures for extraction and purification of leaf wax biomarkers from peats

    Directory of Open Access Journals (Sweden)

    J.E. Nichols

    2011-12-01

    Full Text Available Palaeoecological and palaeoclimate reconstruction, using leaf wax biomarkers, is a relatively new sub-discipline of peatland science. The ability to process large numbers of samples rapidly for biomarkers makes this type of analysis particularly appealing. This review is a guide to the preparation of leaf waxes for analysis by gas chromatography. The main phases of preparation are extraction of soluble organic compounds from sediment, separation of the total extract into fractions of differing polarity, and the derivatisation of polar functional groups. The procedures described here are not meant be exhaustive of all organic geochemical possibilities in peatlands, but a distillation of methods for the preparation of leaf waxes that are commonly and increasingly being used in palaeoecological and palaeoclimatological studies.

  2. Calcium Co-regulates Oxidative Metabolism and ATP Synthase-dependent Respiration in Pancreatic Beta Cells

    Science.gov (United States)

    De Marchi, Umberto; Thevenet, Jonathan; Hermant, Aurelie; Dioum, Elhadji; Wiederkehr, Andreas

    2014-01-01

    Mitochondrial energy metabolism is essential for glucose-induced calcium signaling and, therefore, insulin granule exocytosis in pancreatic beta cells. Calcium signals are sensed by mitochondria acting in concert with mitochondrial substrates for the full activation of the organelle. Here we have studied glucose-induced calcium signaling and energy metabolism in INS-1E insulinoma cells and human islet beta cells. In insulin secreting cells a surprisingly large fraction of total respiration under resting conditions is ATP synthase-independent. We observe that ATP synthase-dependent respiration is markedly increased after glucose stimulation. Glucose also causes a very rapid elevation of oxidative metabolism as was followed by NAD(P)H autofluorescence. However, neither the rate of the glucose-induced increase nor the new steady-state NAD(P)H levels are significantly affected by calcium. Our findings challenge the current view, which has focused mainly on calcium-sensitive dehydrogenases as the target for the activation of mitochondrial energy metabolism. We propose a model of tight calcium-dependent regulation of oxidative metabolism and ATP synthase-dependent respiration in beta cell mitochondria. Coordinated activation of matrix dehydrogenases and respiratory chain activity by calcium allows the respiratory rate to change severalfold with only small or no alterations of the NAD(P)H/NAD(P)+ ratio. PMID:24554722

  3. Divergent Effects of Nitrogen Addition on Soil Respiration in a Semiarid Grassland

    OpenAIRE

    Cheng Zhu; Yiping Ma; Honghui Wu; Tao Sun; Kimberly J. La Pierre; Zewei Sun; Qiang Yu

    2016-01-01

    Nitrogen (N) deposition has been steadily increasing for decades, with consequences for soil respiration. However, we have a limited understanding of how soil respiration responds to N availability. Here, we investigated the soil respiration responses to low and high levels of N addition (0.4?mol N m?2 yr?1 vs 1.6?mol N m?2 yr?1) over a two-year period in a semiarid Leymus chinensis grassland in Inner Mongolia, China. Our results show that low-level N addition increased soil respiration, plan...

  4. Microclimate, canopy structure and photosynthesis in canopies of three contrasting temperate forage grasses. III. Canopy photosynthesis, individual leaf photosynthesis and the distribution of current assimilate

    Energy Technology Data Exchange (ETDEWEB)

    Sheehy, J E

    1977-01-01

    The rates of canopy and individual leaf photosynthesis and /sup 14/C distribution for three temperate forage grasses Lolium perenne cv. S24, L. perenne cv. Reveille and Festuca arundinacea cv. S170 were determined in the field during a summer growth period. Canopy photosynthesis declined as the growth period progressed, reflecting a decline in the photosynthetic capacity of successive youngest fully expanded leaves. The decline in the maximum photosynthetic capacity of the canopies was correlated with a decline in their quantum efficiencies at low irradiance. Changes in canopy structure resulted in changes in canopy net photosynthesis and dark respiration. No clear relationships between changes in the environment and changes in canopy net photosynthesis and dark respiration were established. The relative distributions of /sup 14/C in the shoots of the varieties gave a good indication of the amount of dry matter per ground area in the varieties. 21 references, 4 figures, 1 table.

  5. Hypolipidemic Effect of Psidium guajava Leaf Extract Against Hepatotoxicity in Rats.

    Science.gov (United States)

    Vijayakumar, K; Rengarajan, R L; Radhakrishnan, R; Anand, A Vijaya

    2018-01-01

    Plant-based natural extracts cure several diseases in human. However, the extract of Psidium guajava leaf is not yet evaluated on changes of lipid profile in hepatic disease affected rats. The present study was aimed to evaluate the mitigation effect of the ethanolic extract of P. guajava leaf and its isolated quercetin fraction on hepatotoxic rats. Carbon tetrachloride (CCl 4 ) was injected to rats for hepatic disease induction and silymarin drug was used as positive control to compare plant ethanolic extract. The lipid profiles were assessed in both plasma and liver tissue of diseased and control rats. Levels of total cholesterol, triglycerides, free fatty acids, phospholipids, and low-density lipoprotein cholesterol were increased and the level of high-density lipoprotein cholesterol (HDL-C) was decreased in CCl 4 -induced hepatotoxic rats. The treatment of P. guajava (100, 200, and 300 mg/kg, bw) and isolated quercetin fraction (20 mg/kg, bw) doses decreased the elevated levels of all these parameters in diseased rats and restored the normal concentration of HDL-C. The results of the present study concluded that the P. guajava leaf and its isolated quercetin fraction can significantly regulate lipid metabolism in CCl 4 -induced hepatotoxic rats and decrease the disease rate. Psidium guajava leaf extract reduces the hepatotoxicity and disease rate in ratsQuercetin fraction of leaf extract significantly regulates lipid profile in hepatic diseased rats. Abbreviations used: CCl 4 : Carbon tetrachloride; FFA: Free fatty acids; HDL-C: High-density lipoprotein cholesterol; LCAT: Lecithin cholesterol acyltransferase; LDL-C: Low-density lipoprotein cholesterol; PL: Phospholipids; TC: Total cholesterol; TG: Triglycerides; VLDL-C: Very low-density lipoprotein cholesterol.

  6. Phenophases alter the soil respiration-temperature relationship in an oak-dominated forest

    Science.gov (United States)

    Jared L. DeForest; Askoo Noormets; Steve G. McNulty; Ge Sun; Gwen Teeney; Jiquan Chen

    2006-01-01

    Soil respiration (SR) represents a major component of forest ecosystem respiration and is influenced seasonally by environmental factors such as temperature, soil moisture, root respiration, and litter fall. Changes in these environmental factors correspond with shifts in plant phenology. In this study, we examined the relationship between canopy phenophases @re-growth...

  7. Easy Leaf Area: Automated digital image analysis for rapid and accurate measurement of leaf area.

    Science.gov (United States)

    Easlon, Hsien Ming; Bloom, Arnold J

    2014-07-01

    Measurement of leaf areas from digital photographs has traditionally required significant user input unless backgrounds are carefully masked. Easy Leaf Area was developed to batch process hundreds of Arabidopsis rosette images in minutes, removing background artifacts and saving results to a spreadsheet-ready CSV file. • Easy Leaf Area uses the color ratios of each pixel to distinguish leaves and calibration areas from their background and compares leaf pixel counts to a red calibration area to eliminate the need for camera distance calculations or manual ruler scale measurement that other software methods typically require. Leaf areas estimated by this software from images taken with a camera phone were more accurate than ImageJ estimates from flatbed scanner images. • Easy Leaf Area provides an easy-to-use method for rapid measurement of leaf area and nondestructive estimation of canopy area from digital images.

  8. Automatic respiration tracking for radiotherapy using optical 3D camera

    Science.gov (United States)

    Li, Tuotuo; Geng, Jason; Li, Shidong

    2013-03-01

    Rapid optical three-dimensional (O3D) imaging systems provide accurate digitized 3D surface data in real-time, with no patient contact nor radiation. The accurate 3D surface images offer crucial information in image-guided radiation therapy (IGRT) treatments for accurate patient repositioning and respiration management. However, applications of O3D imaging techniques to image-guided radiotherapy have been clinically challenged by body deformation, pathological and anatomical variations among individual patients, extremely high dimensionality of the 3D surface data, and irregular respiration motion. In existing clinical radiation therapy (RT) procedures target displacements are caused by (1) inter-fractional anatomy changes due to weight, swell, food/water intake; (2) intra-fractional variations from anatomy changes within any treatment session due to voluntary/involuntary physiologic processes (e.g. respiration, muscle relaxation); (3) patient setup misalignment in daily reposition due to user errors; and (4) changes of marker or positioning device, etc. Presently, viable solution is lacking for in-vivo tracking of target motion and anatomy changes during the beam-on time without exposing patient with additional ionized radiation or high magnet field. Current O3D-guided radiotherapy systems relay on selected points or areas in the 3D surface to track surface motion. The configuration of the marks or areas may change with time that makes it inconsistent in quantifying and interpreting the respiration patterns. To meet the challenge of performing real-time respiration tracking using O3D imaging technology in IGRT, we propose a new approach to automatic respiration motion analysis based on linear dimensionality reduction technique based on PCA (principle component analysis). Optical 3D image sequence is decomposed with principle component analysis into a limited number of independent (orthogonal) motion patterns (a low dimension eigen-space span by eigen-vectors). New

  9. Carbon dioxide titration method for soil respiration measurements

    OpenAIRE

    Martín Rubio, Luis

    2017-01-01

    This thesis was commissioned by Tampere University of Applied Sciences, which was interested in studying and developing a titration measurement method for soil respiration and biodegradability. Some experiments were carried out measuring soil respiration for testing the method and others adding some biodegradable material like polylactic acid compressed material and 100% biodegradable plastic bags to test its biodegradability and the possibility to measure it via titration. The thesi...

  10. The effect of respiration buffer composition on mitochondrial metabolism and function

    OpenAIRE

    Wollenman, Lucas C.; Vander Ploeg, Matthew R.; Miller, Mackinzie L.; Zhang, Yizhu; Bazil, Jason N.

    2017-01-01

    Functional studies on isolated mitochondria critically rely on the right choice of respiration buffer. Differences in buffer composition can lead to dramatically different respiration rates leading to difficulties in comparing prior studies. The ideal buffer facilities high ADP-stimulated respiratory rates and minimizes substrate transport effects so that the ability to distinguish between various treatments and conditions is maximal. In this study, we analyzed a variety of respiration buffer...

  11. Increasing Leaf Vein Density via Mutagenesis in Rice Results in an Enhanced Rate of Photosynthesis, Smaller Cell Sizes and Can Reduce Interveinal Mesophyll Cell Number

    Directory of Open Access Journals (Sweden)

    Aryo B. Feldman

    2017-11-01

    Full Text Available Improvements to leaf photosynthetic rates of crops can be achieved by targeted manipulation of individual component processes, such as the activity and properties of RuBisCO or photoprotection. This study shows that simple forward genetic screens of mutant populations can also be used to rapidly generate photosynthesis variants that are useful for breeding. Increasing leaf vein density (concentration of vascular tissue per unit leaf area has important implications for plant hydraulic properties and assimilate transport. It was an important step to improving photosynthetic rates in the evolution of both C3 and C4 species and is a foundation or prerequisite trait for C4 engineering in crops like rice (Oryza sativa. A previous high throughput screen identified five mutant rice lines (cv. IR64 with increased vein densities and associated narrower leaf widths (Feldman et al., 2014. Here, these high vein density rice variants were analyzed for properties related to photosynthesis. Two lines were identified as having significantly reduced mesophyll to bundle sheath cell number ratios. All five lines had 20% higher light saturated photosynthetic capacity per unit leaf area, higher maximum carboxylation rates, dark respiration rates and electron transport capacities. This was associated with no significant differences in leaf thickness, stomatal conductance or CO2 compensation point between mutants and the wild-type. The enhanced photosynthetic rate in these lines may be a result of increased RuBisCO and electron transport component amount and/or activity and/or enhanced transport of photoassimilates. We conclude that high vein density (associated with altered mesophyll cell length and number is a trait that may confer increased photosynthetic efficiency without increased transpiration.

  12. Leaf anatomical traits determine the 18O enrichment of leaf water in coastal halophytes

    Science.gov (United States)

    Liang, J.; Lin, G., Sr.; Sternberg, L. O.

    2017-12-01

    Foliar anatomical adaptations to high-salinity environment in mangroves may be recorded by leaf water isotopes. Recent studies observed that a few mangrove species have lower 18O enrichment of leaf water (ΔL) relative to source water than the adjacent terrestrial trees, but what factors actually control this phenomenon is still disputable at present. To resolve this issue, we collected 15 species of true mangrove plants, 14 species of adjacent freshwater trees and 4 species of semi-mangrove plants at five study sites on the southeastern coast of China. Leaf stomatal density and pore size, water content, ΔL and other related leaf physiological traits were determined for the selected leaves of these plants. Our results confirmed that ΔL values of mangroves were generally 3 4 ‰ lower than those of the adjacent freshwater or semi-mangrove species. Higher leaf water per area (LWC) and lower leaf stomatal density (LS) of mangroves played co-dominant roles in lowering ΔL through elongating effective leaf mixing length by about 20%. The Péclet model incorporated by LWC and LS performed well in predicting ΔL. The demonstrated general law between leaf anatomy and ΔL in this paper based on a large pool of species bridges the gap between leaf functional traits and metabolic proxies derived ΔL, which will have considerable potential applications in vegetation succession and reconstruction of paleoclimate research.

  13. [Soil respiration characteristics in winter wheat field in North China Plain].

    Science.gov (United States)

    Chen, Shuyue; Li, Jun; Lu, Peiling; Wang, Yinghong; Yu, Qiang

    2004-09-01

    Experiments were conducted at the Yucheng Comprehensive Experimental Station of the Chinese Academy of Sciences during 2002-2003 to investigate the respiration of a pulverous sandstone soil under cultivation of winter wheat over a growth season. The effluent CO2 was collected and analyzed by the static-chamber/gas chromatography (GC) method at a frequency of once a week in spring and autumn, once two weeks in winter, twice a week for straw manure treatment, once a week for no straw manure treatment and nitrogen fertilization treatment in summer. The results indicated that diurnal variation of soil respiration rate showed a single peak in typical winter wheat farmlands in the North China Plain, and reached the highest at about 13 o'clock, and the lowest at about 4 o'clock in the early morning. In winter wheat growth season, the soil respiration rate was 31.23-606.85 mg x m(-2) x h(-1) under straw manure, 28.99-549.66 x m(-2) x h(-1) under no straw manure, 10.46-590.86 mg x m(-2) x h(-1) in N0, 16.11-349.88 mg x m(-2) x h(-1) in N100, 12.25-415.00 mg x m(-2) x h(-1) in N200, and 23.01-410.58 mg x m(-2) x h(-1) in N300, showing a similar seasonal variation tendency with soil temperature. Among all treatments, the straw manure had the most distinct soil respiration, though the soil respiration also increased slightly with increasing nitrogen fertilization. Soil respiration increased exponentially with increasing soil temperature, and the correlation of soil temperature at the depth of 5 cm was the best. This relationship was usually described with the Q10 model, which represented the sensitivity of soil respiration to temperature. Q10 was not a fixed value, which varied with the depth at which the temperature was measured and the depth of the active soil layer and soil temperature. At same time, the Q10 value decreased with increasing soil temperature. Soil water content was another important factor affecting soil respiration rate, but in this region, the relationship

  14. Occurrence of barley leaf disease and control strategies in Denmark

    DEFF Research Database (Denmark)

    Jørgensen, Lise Nistrup; Ørum, Jens Erik; Heick, Thies Marten

    Barley (Hordeum vulgare) is one of the major crops in Denmark and of special importance for malting and for pig feed. In 2016, the crop was grown covering a total area of 700,000 ha; approximately 25% of arable area in Denmark. To ensure high yield of around 60 dt ha-1, disease-tolerant cultivars...... have proven to be quite effective against all leaf diseases, aside from brown rust and mildew. Denmark has a national record system for pesticide usages. All farmers upload their fungicide use by crop, creating a good basis for assessing the differences in use pattern across different regions...... and fungicide treatments are required. Each year, barley cultivars are assessed for susceptibility towards leaf diseases in national observation plots. The most predominant fungal leaf diseases in Denmark are barley scald (Rhynchosporium secalis), net blotch (Pyrenophora teres), brown rust (Puccinia hordei...

  15. Algorithm for retrieving vegetative canopy and leaf parameters from multi- and hyperspectral imagery

    Science.gov (United States)

    Borel, Christoph

    2009-05-01

    In recent years hyper-spectral data has been used to retrieve information about vegetative canopies such as leaf area index and canopy water content. For the environmental scientist these two parameters are valuable, but there is potentially more information to be gained as high spatial resolution data becomes available. We developed an Amoeba (Nelder-Mead or Simplex) based program to invert a vegetative canopy radiosity model coupled with a leaf (PROSPECT5) reflectance model and modeled for the background reflectance (e.g. soil, water, leaf litter) to a measured reflectance spectrum. The PROSPECT5 leaf model has five parameters: leaf structure parameter Nstru, chlorophyll a+b concentration Cab, carotenoids content Car, equivalent water thickness Cw and dry matter content Cm. The canopy model has two parameters: total leaf area index (LAI) and number of layers. The background reflectance model is either a single reflectance spectrum from a spectral library() derived from a bare area pixel on an image or a linear mixture of soil spectra. We summarize the radiosity model of a layered canopy and give references to the leaf/needle models. The method is then tested on simulated and measured data. We investigate the uniqueness, limitations and accuracy of the retrieved parameters on canopy parameters (low, medium and high leaf area index) spectral resolution (32 to 211 band hyperspectral), sensor noise and initial conditions.

  16. Calibrations between chlorophyll meter values and chlorophyll contents vary as the result of differences in leaf structure

    Science.gov (United States)

    In order to relate leaf chlorophyll meter values with total leaf chlorophyll contents (µg cm-2), calibration equations are established with measured data on leaves. Many studies have documented differences in calibration equations using different species and using different growing conditions for th...

  17. Soil respiration in different agricultural and natural ecosystems in an arid region.

    Science.gov (United States)

    Lai, Liming; Zhao, Xuechun; Jiang, Lianhe; Wang, Yongji; Luo, Liangguo; Zheng, Yuanrun; Chen, Xi; Rimmington, Glyn M

    2012-01-01

    The variation of different ecosystems on the terrestrial carbon balance is predicted to be large. We investigated a typical arid region with widespread saline/alkaline soils, and evaluated soil respiration of different agricultural and natural ecosystems. Soil respiration for five ecosystems together with soil temperature, soil moisture, soil pH, soil electric conductivity and soil organic carbon content were investigated in the field. Comparing with the natural ecosystems, the mean seasonal soil respiration rates of the agricultural ecosystems were 96%-386% higher and agricultural ecosystems exhibited lower CO(2) absorption by the saline/alkaline soil. Soil temperature and moisture together explained 48%, 86%, 84%, 54% and 54% of the seasonal variations of soil respiration in the five ecosystems, respectively. There was a significant negative relationship between soil respiration and soil electrical conductivity, but a weak correlation between soil respiration and soil pH or soil organic carbon content. Our results showed that soil CO(2) emissions were significantly different among different agricultural and natural ecosystems, although we caution that this was an observational, not manipulative, study. Temperature at the soil surface and electric conductivity were the main driving factors of soil respiration across the five ecosystems. Care should be taken when converting native vegetation into cropland from the point of view of greenhouse gas emissions.

  18. Significance of heme-based respiration in meat spoilage caused by Leuconostoc gasicomitatum.

    Science.gov (United States)

    Jääskeläinen, Elina; Johansson, Per; Kostiainen, Olli; Nieminen, Timo; Schmidt, Georg; Somervuo, Panu; Mohsina, Marzia; Vanninen, Paula; Auvinen, Petri; Björkroth, Johanna

    2013-02-01

    Leuconostoc gasicomitatum is a psychrotrophic lactic acid bacterium (LAB) which causes spoilage in cold-stored modified-atmosphere-packaged (MAP) meat products. In addition to the fermentative metabolism, L. gasicomitatum is able to respire when exogenous heme and oxygen are available. In this study, we investigated the respiration effects on growth rate, biomass, gene expression, and volatile organic compound (VOC) production in laboratory media and pork loin. The meat samples were evaluated by a sensory panel every second or third day for 29 days. We observed that functional respiration increased the growth (rate and yield) of L. gasicomitatum in laboratory media with added heme and in situ meat with endogenous heme. Respiration increased enormously (up to 2,600-fold) the accumulation of acetoin and diacetyl, which are buttery off-odor compounds in meat. Our transcriptome analyses showed that the gene expression patterns were quite similar, irrespective of whether respiration was turned off by excluding heme from the medium or mutating the cydB gene, which is essential in the respiratory chain. The respiration-based growth of L. gasicomitatum in meat was obtained in terms of population development and subsequent development of sensory characteristics. Respiration is thus a key factor explaining why L. gasicomitatum is so well adapted in high-oxygen packed meat.

  19. Herd protection effect of N95 respirators in healthcare workers.

    Science.gov (United States)

    Chen, Xin; Chughtai, Abrar Ahmad; MacIntyre, Chandini Raina

    2017-12-01

    Objective To determine if there was herd protection conferred to unprotected healthcare workers (HCWs) by N95 respirators worn by colleagues. Methods Data were analysed from a prospective cluster randomized clinical trial conducted in Beijing, China between 1 December 2008 and 15 January 2009. A minimum compliance level (MCL) of N95 respirators for prevention of clinical respiratory illness (CRI) was set based on various compliance cut-offs. The CRI rates were compared between compliant (≥MCL) and non-compliant (protection from use of N95 respirators by colleagues within a hospital ward.

  20. Action of γ-rays on the respiration and growth of perilla

    International Nuclear Information System (INIS)

    Sergeeva, E.A.

    1976-01-01

    The respiration rate of leaves of different stroyes and the growth rate of the main steam of perilla plants have been studied after irradiation with γ-rays (3 and 6 kR). Three periods have been distinguished in the rate of the processes under study. The growth and respiration were inhibited in the initial post-irradiation period, then their rate increased till it exceeded the control values at the end of the restoration period. During the subsequent third period, the rate of growth and respiration processes decreased reaching the values observed in unirradiated plants. Changes in the radiosensitive process of growth of irradiated plants are suggested to be the cause for changes in the respiration rate

  1. Impact of Altered Precipitation Patterns on Plant Productivity and Soil Respiration in a Northern Great Plains Grassland

    Science.gov (United States)

    Haase, L.; Flanagan, L. B.

    2017-12-01

    Precipitation patterns are expected to shift towards larger but fewer rain events, with longer intermittent dry periods, associated with climate change. The larger rain events may compensate for and help to mitigate climate change effects on key ecosystem functions such as plant productivity and soil respiration in semi-arid grasslands. We experimentally manipulated the amount and frequency of simulated precipitation added to trenched, treatment plots that were covered by rain shelters, and measured the response in plant productivity and soil respiration in a native, grassland ecosystem near Lethbridge, Alberta. We compared the observed responses to the predictions of a conceptual ecosystem response model developed by Knapp et al. 2008 (BioScience 58: 811-821). Two experiments were conducted during 14 weeks of the growing season from May-August. The first experiment (normal amount) applied total growing season precipitation of 180 mm (climate normal), and the second experiment (reduced amount) applied total precipitation of 90 mm. In both experiments, precipitation was applied at two frequencies, 1 rain event every week (normal frequency) and 1 rain event every two weeks (reduced frequency). In the normal amount experiment, the average rain event was 12.8 mm for the normal frequency treatment and 25.8 mm for the reduced frequency treatment. In the reduced amount experiment, the average rain event was 6.4 mm for the normal frequency treatment and 12.8 mm for the reduced frequency treatment. We hypothesized that larger but fewer rain events would result in increased plant productivity and soil respiration for both experiments. Plant greenness values calculated from digital photographs were used as a proxy for plant productivity, and showed significantly higher values for the normal vs. reduced amount experiment. Soil respiration rate also showed significantly higher values for the normal vs. reduced amount experiment. No significant treatment effect could be detected

  2. Effects of different potting growing media for Petunia grandiflora and Nicotiana alata Link & Otto on photosynthetic capacity, leaf area, and flowering potential

    Directory of Open Access Journals (Sweden)

    Gheorghe Cristian Popescu

    2015-03-01

    Full Text Available Petunia grandiflora Juss. and Nicotiana alata Link & Otto are two of the most widely spread plants on the market for annual potted ornamental plants. In order to identify the most adequate substrate formula we analyzed the effects of different potting growing media used for P. hybrida grandiflora 'Bravo' and N. alata 'Dinamo' on their photosynthetic capacity, leaf area, and flowering potential. Optimization of growing media formula for petunia and ornamental tobacco was performed by preparing four growing media mixing fallow soil (FS, Biolan peat (BP, acid peat (AP, leaf compost (C, and perlite (P in different proportions. The physiological potential of petunia and ornamental tobacco was investigated by photosynthesis and respiration rate and chlorophyll pigments in leaves, while the vegetative and flowering phenological stages were evaluated by number of leaves per plant, leaf area, number of flowers per plant and leaf area/flowers ratio. These measurements were significantly influenced by the different potting growing media used in this study. In the flowering stage, the highest photosynthesis rates (8.612 μmol CO2 m-2 s-1 as well as leaf area (1.766 dm² of petunias were obtained on growing media with 60% biolan peat, 30% acid peat and 10% perlite (BP60-AP30-P10. Flowering responses to growing conditions vary greatly among plants and the biggest number of ornamental tobacco flowers (22 flowers plant-1 was registered as an effect of BP60-AP30-P10 media. Growing media with the BP60-AP30-P10 formula seem to be the most adequate growth substrate to develop profitable crops for petunias and ornamental tobacco with high decorative value.

  3. Effect of Simvastatin, Coenzyme Q10, Resveratrol, Acetylcysteine and Acetylcarnitine on Mitochondrial Respiration.

    Science.gov (United States)

    Fišar, Z; Hroudová, J; Singh, N; Kopřivová, A; Macečková, D

    2016-01-01

    Some therapeutic and/or adverse effects of drugs may be related to their effects on mitochondrial function. The effects of simvastatin, resveratrol, coenzyme Q10, acetylcysteine, and acetylcarnitine on Complex I-, Complex II-, or Complex IV-linked respiratory rate were determined in isolated brain mitochondria. The protective effects of these biologically active compounds on the calcium-induced decrease of the respiratory rate were also studied. We observed a significant inhibitory effect of simvastatin on mitochondrial respiration (IC50 = 24.0 μM for Complex I-linked respiration, IC50 = 31.3 μM for Complex II-linked respiration, and IC50 = 42.9 μM for Complex IV-linked respiration); the inhibitory effect of resveratrol was found at very high concentrations (IC50 = 162 μM for Complex I-linked respiration, IC50 = 564 μM for Complex II-linked respiration, and IC50 = 1454 μM for Complex IV-linked respiration). Concentrations required for effective simvastatin- or resveratrol-induced inhibition of mitochondrial respiration were found much higher than concentrations achieved under standard dosing of these drugs. Acetylcysteine and acetylcarnitine did not affect the oxygen consumption rate of mitochondria. Coenzyme Q10 induced an increase of Complex I-linked respiration. The increase of free calcium ions induced partial inhibition of the Complex I+II-linked mitochondrial respiration, and all tested drugs counteracted this inhibition. None of the tested drugs showed mitochondrial toxicity (characterized by respiratory rate inhibition) at drug concentrations achieved at therapeutic drug intake. Resveratrol, simvastatin, and acetylcarnitine had the greatest neuroprotective potential (characterized by protective effects against calcium-induced reduction of the respiratory rate).

  4. Evaluation of respiration-correlated digital tomosynthesis in lung.

    Science.gov (United States)

    Santoro, Joseph; Kriminski, Sergey; Lovelock, D Michael; Rosenzweig, Kenneth; Mostafavi, Hassan; Amols, Howard I; Mageras, Gig S

    2010-03-01

    Digital tomosynthesis (DTS) with a linear accelerator-mounted imaging system provides a means of reconstructing tomographic images from radiographic projections over a limited gantry arc, thus requiring only a few seconds to acquire. Its application in the thorax, however, often results in blurred images from respiration-induced motion. This work evaluates the feasibility of respiration-correlated (RC) DTS for soft-tissue visualization and patient positioning. Image data acquired with a gantry-mounted kilovoltage imaging system while recording respiration were retrospectively analyzed from patients receiving radiotherapy for non-small-cell lung carcinoma. Projection images spanning an approximately 30 degrees gantry arc were sorted into four respiration phase bins prior to DTS reconstruction, which uses a backprojection, followed by a procedure to suppress structures above and below the reconstruction plane of interest. The DTS images were reconstructed in planes at different depths through the patient and normal to a user-selected angle close to the center of the arc. The localization accuracy of RC-DTS was assessed via a comparison with CBCT. Evaluation of RC-DTS in eight tumors shows visible reduction in image blur caused by the respiratory motion. It also allows the visualization of tumor motion extent. The best image quality is achieved at the end-exhalation phase of the respiratory motion. Comparison of RC-DTS with respiration-correlated cone-beam CT in determining tumor position, motion extent and displacement between treatment sessions shows agreement in most cases within 2-3 mm, comparable in magnitude to the intraobserver repeatability of the measurement. These results suggest the method's applicability for soft-tissue image guidance in lung, but must be confirmed with further studies in larger numbers of patients.

  5. Soil respiration response to experimental disturbances over 3 years

    Science.gov (United States)

    Amy Concilio; Siyan Ma; Soung-Ryoul Ryu; Malcolm North; Jiquan Chen

    2006-01-01

    Soil respiration is a major pathway for carbon cycling in terrestrial ecosystems yet little is known about its response to natural and anthropogenic disturbances. This study examined soil respiration response to prescribed burning and thinning treatments in an old-growth, mixed-conifer forest on the western slope of the Sierra Nevada Mountains. Experimental treatments...

  6. Respiration of the external mycelium in the arbuscular mycorrhizal symbiosis shows strong dependence on recent photosynthates and acclimation to temperature.

    Science.gov (United States)

    Heinemeyer, A; Ineson, P; Ostle, N; Fitter, A H

    2006-01-01

    * Although arbuscular mycorrhizal (AM) fungi are a major pathway in the global carbon cycle, their basic biology and, in particular, their respiratory response to temperature remain obscure. * A pulse label of the stable isotope (13)C was applied to Plantago lanceolata, either uninoculated or inoculated with the AM fungus Glomus mosseae. The extra-radical mycelium (ERM) of the fungus was allowed to grow into a separate hyphal compartment excluding roots. We determined the carbon costs of the ERM and tested for a direct temperature effect on its respiration by measuring total carbon and the (13)C:(12)C ratio of respired CO(2). With a second pulse we tested for acclimation of ERM respiration after 2 wk of soil warming. * Root colonization remained unchanged between the two pulses but warming the hyphal compartment increased ERM length. delta(13)C signals peaked within the first 10 h and were higher in mycorrhizal treatments. The concentration of CO(2) in the gas samples fluctuated diurnally and was highest in the mycorrhizal treatments but was unaffected by temperature. Heating increased ERM respiration only after the first pulse and reduced specific ERM respiration rates after the second pulse; however, both pulses strongly depended on radiation flux. * The results indicate a fast ERM acclimation to temperature, and that light is the key factor controlling carbon allocation to the fungus.

  7. Video-based respiration monitoring with automatic region of interest detection

    NARCIS (Netherlands)

    Janssen, R.J.M.; Wang, Wenjin; Moço, A.; de Haan, G.

    2016-01-01

    Vital signs monitoring is ubiquitous in clinical environments and emerging in home-based healthcare applications. Still, since current monitoring methods require uncomfortable sensors, respiration rate remains the least measured vital sign. In this paper, we propose a video-based respiration

  8. Annual ecosystem respiration budget for a Pinus sylvestris stand in central Siberia

    International Nuclear Information System (INIS)

    Shibistova, O.; Zrazhevskaya, G.; Astrakhantceva, N.; Shijneva, I.; Lloyd, J.; Arneth, A.; Kolle, J.; Knohl, A.; Schmerler, J.

    2002-01-01

    Using a ground-based and an above-canopy eddy covariance system in addition to stem respiration measurements, the annual respiratory fluxes attributable to soil, stems and foliage were determined for a Scots pine (Pinus sylvestris L.) forest growing in central Siberia. Night-time foliar respiration was estimated on the basis of the difference between fluxes measured below and above the canopy and the stem respiration measurements. Comparison of the effects of night-time turbulence on measured CO 2 fluxes showed flux loss above the canopy at low wind speeds, but no such effect was observed for the ground-based eddy system. This suggests that problems with flow homogeneity or flux divergence (both of which would be expected to be greater above the canopy than below) were responsible for above-canopy losses under these conditions. After correcting for this, a strong seasonality in foliar respiration was observed. This was not solely attributable to temperature variations, with intrinsic foliar respiratory capacities being much greater in spring and autumn. The opposite pattern was observed for stem respiration, with the intrinsic respiratory capacity being lower from autumn through early spring. Maximum respiratory activity was observed in early summer. This was not simply associated with a response to higher temperatures but seemed closely linked with cambial activity and the development of new xylem elements. Soil respiration rates exhibited an apparent high sensitivity to temperature, with seasonal data implying a Q 10 of about 7. We interpret this as reflecting covarying changes in soil microbial activity and soil temperatures throughout the snow-free season. Averaged over the two study years (1999 and 2000), the annual respiratory flux was estimated at 38.3 mol C/m 2 /a. Of this 0.61 was attributable to soil respiration, with stem respiration accounting for 0.21 and foliar respiration 0.18

  9. Amplification and dampening of soil respiration by changes in temperature variability

    Directory of Open Access Journals (Sweden)

    C. A. Sierra

    2011-04-01

    Full Text Available Accelerated release of carbon from soils is one of the most important feedbacks related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature variability. Anthropogenic activities are likely to modify both the average state and the variability of the climatic system; therefore, the effects of future warming on decomposition should not only focus on trends in the average temperature, but also variability expressed as a change of the probability distribution of temperature. Using analytical and numerical analyses we tested common relationships between temperature and respiration and found that the variability of temperature plays an important role determining respiration rates of soil organic matter. Changes in temperature variability, without changes in the average temperature, can affect the amount of carbon released through respiration over the long-term. Furthermore, simultaneous changes in the average and variance of temperature can either amplify or dampen the release of carbon through soil respiration as climate regimes change. These effects depend on the degree of convexity of the relationship between temperature and respiration and the magnitude of the change in temperature variance. A potential consequence of this effect of variability would be higher respiration in regions where both the mean and variance of temperature are expected to increase, such as in some low latitude regions; and lower amounts of respiration where the average temperature is expected to increase and the variance to decrease, such as in northern high latitudes.

  10. Amplification and dampening of soil respiration by changes in temperature variability

    Science.gov (United States)

    Sierra, C.A.; Harmon, M.E.; Thomann, E.; Perakis, S.S.; Loescher, H.W.

    2011-01-01

    Accelerated release of carbon from soils is one of the most important feed backs related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature vari-ability. Anthropogenic activities are likely to modify both the average state and the variability of the climatic system; therefore, the effects of future warming on decomposition should not only focus on trends in the average temperature, but also variability expressed as a change of the probability distribution of temperature.Using analytical and numerical analyses we tested common relationships between temperature and respiration and found that the variability of temperature plays an important role determining respiration rates of soil organic matter. Changes in temperature variability, without changes in the average temperature, can affect the amount of carbon released through respiration over the long term. Furthermore, simultaneous changes in the average and variance of temperature can either amplify or dampen there release of carbon through soil respiration as climate regimes change. The effects depend on the degree of convexity of the relationship between temperature and respiration and the magnitude of the change in temperature variance. A potential consequence of this effect of variability would be higher respiration in regions where both the mean and variance of temperature are expected to increase, such as in some low latitude regions; and lower amounts of respiration where the average temperature is expected to increase and the variance to decrease, such as in northern high latitudes.

  11. Leaf chemical composition of twenty-one Populus hybrid clones grown under intensive culture

    Science.gov (United States)

    Richard E. Dickson; Philip R. Larson

    1976-01-01

    Leaf material from 21 nursery-grown Populus hybrid clones was analyzed for three nitrogen fractions (total N, soluble protein, and soluble amino acids) and three carbhydrate fractions (reducing sugars, total soluble sugars, and total nonstructural carbohydrates-TNC). In addition, nursery-grown green ash and silver maple, field-grown bigtooth and trembling aspen, and...

  12. Leaf endophyte load influences fungal garden development in leaf-cutting ants

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    Van Bael Sunshine A

    2012-11-01

    Full Text Available Abstract Background Previous work has shown that leaf-cutting ants prefer to cut leaf material with relatively low fungal endophyte content. This preference suggests that fungal endophytes exact a cost on the ants or on the development of their colonies. We hypothesized that endophytes may play a role in their host plants’ defense against leaf-cutting ants. To measure the long-term cost to the ant colony of fungal endophytes in their forage material, we conducted a 20-week laboratory experiment to measure fungal garden development for colonies that foraged on leaves with low or high endophyte content. Results Colony mass and the fungal garden dry mass did not differ significantly between the low and high endophyte feeding treatments. There was, however, a marginally significant trend toward greater mass of fungal garden per ant worker in the low relative to the high endophyte treatment. This trend was driven by differences in the fungal garden mass per worker from the earliest samples, when leaf-cutting ants had been foraging on low or high endophyte leaf material for only 2 weeks. At two weeks of foraging, the mean fungal garden mass per worker was 77% greater for colonies foraging on leaves with low relative to high endophyte loads. Conclusions Our data suggest that the cost of endophyte presence in ant forage material may be greatest to fungal colony development in its earliest stages, when there are few workers available to forage and to clean leaf material. This coincides with a period of high mortality for incipient colonies in the field. We discuss how the endophyte-leaf-cutter ant interaction may parallel constitutive defenses in plants, whereby endophytes reduce the rate of colony development when its risk of mortality is greatest.

  13. Changes in respiration rates and biomass attributes of epilithon due to extended exposure to zinc

    International Nuclear Information System (INIS)

    Colwell, F.S.

    1986-01-01

    The purpose of this research was to determine the influence of extended dosing of zinc on the carbon cycling and biomass characteristics of freshwater epilithon. Experiments were conducted in artificial streams continuously dosed with 0.00, 0.05, or 1.00 mg Zn liter -1 for 20 to 30 days during summer and fall, 1984 and 1985. Repeated measurement of epilithon structure and function included estimates of 14 C-glucose respiration, 14 C-glutamate respiration, O 2 and CO 2 flux rates, ash-free dry weight (AFDW), protein, carbohydrate, and algal pigment concentrations, and total and zinc-tolerant colony forming units. An increase in epilithic glucose respiration per unit biomass consistently occurred 5 to 10 days after dosing with 1.0 mg Zn liter -1 was started. At the same time significantly lower epilithon biomass occurred in the high dosed streams relative to controls in 3 out of 4 studies. Although algal pigment concentrations were lowest in the high dose streams at the midpoint of the studies, the chlorophyll a-to-pheophytin a ratio remained high, indicating that the minimal algal population was not senescing in situ. After 30 days, the epilithon dosed with 1.0 mg Zn liter -1 had higher AFDW, protein, and carbohydrate concentrations than the other treatments. The development of unique epilithon communities that are acclimated to prolonged zinc exposure is evident in the eventual recolonization of the artificial surfaces, glucose respiration rates that are comparable to controls, and presence of zinc-tolerant heterotrophs

  14. Short-term natural δ13C and δ18O variations in pools and fluxes in a beech forest: the transfer of isotopic signal from recent photosynthates to soil respired CO2

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    G. Matteucci

    2011-10-01

    Full Text Available The fate of photosynthetic products within the plant-soil continuum determines how long the reduced carbon resides within the ecosystem and when it returns back to the atmosphere in the form of respiratory CO2. We have tested the possibility of measuring natural variation in δ13C and δ18O to disentangle the potential times needed to transfer carbohydrates produced by photosynthesis down to trunk, roots and, in general, to belowground up to its further release in the form of soil respiration into the atmosphere in a beech (Fagus sylvatica forest. We have measured the variation in stable carbon and oxygen isotope compositions in plant material and in soil respired CO2 every three hours for three consecutive days. Possible steps and different signs of post-photosynthetic fractionation during carbon translocation were also identified. A 12 h-periodicity was observed for variation in δ13C in soluble sugars in the top crown leaves and it can be explained by starch day/night dynamics in synthesis and breakdown and by stomatal limitations under elevated vapour pressure deficits. Photosynthetic products were transported down the trunk and mixed with older carbon pools, therefore causing the dampening of the δ13C signal variation. The strongest periodicity of 24 h was found in δ13C in soil respiration indicating changes in root contribution to the total CO2 efflux. Other non-biological causes like diffusion fractionation and advection induced by gas withdrawn from the measurement chamber complicate data interpretation on this step of C transfer path. Nevertheless, it was possible to identify the speed of carbohydrates' translocation from the point of assimilation to the trunk breast height because leaf-imprinted enrichment of δ18O in soluble sugars was less modified along the downward transport and was well related to environmental parameters potentially linked to stomatal conductance. The speed of carbohydrates translocation from the site of

  15. Phenotypic Plasticity of Leaf Shape along a Temperature Gradient in Acer rubrum

    Science.gov (United States)

    Royer, Dana L.; Meyerson, Laura A.; Robertson, Kevin M.; Adams, Jonathan M.

    2009-01-01

    Both phenotypic plasticity and genetic determination can be important for understanding how plants respond to environmental change. However, little is known about the plastic response of leaf teeth and leaf dissection to temperature. This gap is critical because these leaf traits are commonly used to reconstruct paleoclimate from fossils, and such studies tacitly assume that traits measured from fossils reflect the environment at the time of their deposition, even during periods of rapid climate change. We measured leaf size and shape in Acer rubrum derived from four seed sources with a broad temperature range and grown for two years in two gardens with contrasting climates (Rhode Island and Florida). Leaves in the Rhode Island garden have more teeth and are more highly dissected than leaves in Florida from the same seed source. Plasticity in these variables accounts for at least 6–19 % of the total variance, while genetic differences among ecotypes probably account for at most 69–87 %. This study highlights the role of phenotypic plasticity in leaf-climate relationships. We suggest that variables related to tooth count and leaf dissection in A. rubrum can respond quickly to climate change, which increases confidence in paleoclimate methods that use these variables. PMID:19893620

  16. Easy Leaf Area: Automated Digital Image Analysis for Rapid and Accurate Measurement of Leaf Area

    Directory of Open Access Journals (Sweden)

    Hsien Ming Easlon

    2014-07-01

    Full Text Available Premise of the study: Measurement of leaf areas from digital photographs has traditionally required significant user input unless backgrounds are carefully masked. Easy Leaf Area was developed to batch process hundreds of Arabidopsis rosette images in minutes, removing background artifacts and saving results to a spreadsheet-ready CSV file. Methods and Results: Easy Leaf Area uses the color ratios of each pixel to distinguish leaves and calibration areas from their background and compares leaf pixel counts to a red calibration area to eliminate the need for camera distance calculations or manual ruler scale measurement that other software methods typically require. Leaf areas estimated by this software from images taken with a camera phone were more accurate than ImageJ estimates from flatbed scanner images. Conclusions: Easy Leaf Area provides an easy-to-use method for rapid measurement of leaf area and nondestructive estimation of canopy area from digital images.

  17. Effect of Packaging Materials on Orthosiphon Stamineus Dried-Leaf Quality During Storage

    Science.gov (United States)

    Norawanis, A. R.; Shaari, A. R.; Leng, L. Y.

    2018-03-01

    The experiment was conducted to determine the effects on the total phenolic content, antioxidant capacity, moisture content and total different color (ΔE) when the O. stamineus dried whole-leaf were packed in different packaging materials (plastic bag, paper bag and glass container) and stored under room temperature (±25 °C) and relative humidity (±65 %RH) for 8 weeks. The total phenolic compounds and antioxidant activity were measured using the Folin-Ciocalteu method and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity assay respectively, and analyzed using UV/VIS Spectrophotometer. The moisture content changes were examined using a moisture analyzer and the color changes were analyzed using colorimeter. The results showed that packing O. stamineus dried whole-leaf in different packaging materials significantly affected the herbal leaves quality. After 8 weeks of storage period, the total phenolic content and antioxidant capacity exhibited the increase values during storage. Meanwhile, the moisture content of the samples decreased by storage period for the samples packed in plastic bag and glass container. The moisture content of the samples packed in the paper bag fluctuated along the 8 weeks of storage period. The total different color (ΔE) of the O. stamineus dried whole-leaf increased by storage period. The highest changes of ΔE belonged to the samples packed in the glass container, followed by paper and plastic bags. The selection of the packaging materials can be considered as an important element to control the quality of raw herbal materials for further processing and the herbal finished products.

  18. ACTIVITY TEST OF GUAVA (Psidium guajava L. LEAF METHANOL EXTRACT AS CONTRACEPTION ANTIFERTILITY TO WHITE MICE (Rattus norvegicus

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    Sri Retno Dwi Ariani

    2010-06-01

    Full Text Available The aim of this research is to know about if the guava (Psidium guajava L. leaf methanol extract on 10.5 mg/mL and 21.0 mg/mL dossages indicate a positive test as contraception antifertility to white mice (Rattus norvegicus. The sample is guava leaf from Mungkid, Magelang Central of Java Indonesia. The animals experiment are the white mice on 140-300 g for female, 200-250 g for male and about 3 months of age in average. The steps of this research are : (1 preparing  sample, i.e. washing, drying on to indirect sunlight and make the sample into powder, (2 isolation the guava leaf powder in soxhlet instrument with hexane, (3 evaporation the sample with rotary evaporator until guava leaf hexane extract produced, (4 maseration the sample with methanol, (5 evaporation the sample with rotary evaporator until guava leaf methanol extract produced, (6 conducting contraception antifertility activity test to guave leaf methanol extract on 10.5 mg/mL and 21.0 mg/mL dossages to mice white. The results of this research are guava leaf methanol extract on 10.5 mg/mL and 21.0 mg/mL dossages indicate a negative contraception antifertility test to white mice but in these dossages have indicated that an antiimplantation effect (the total natality of fetus is less than the total implantation site in mice white.   Keywords: Guava leaf, contraseption antifertility, methanol extract, white mice, implantation

  19. Plant community structure regulates responses of prairie soil respiration to decadal experimental warming.

    Science.gov (United States)

    Xu, Xia; Shi, Zheng; Li, Dejun; Zhou, Xuhui; Sherry, Rebecca A; Luo, Yiqi

    2015-10-01

    Soil respiration is recognized to be influenced by temperature, moisture, and ecosystem production. However, little is known about how plant community structure regulates responses of soil respiration to climate change. Here, we used a 13-year field warming experiment to explore the mechanisms underlying plant community regulation on feedbacks of soil respiration to climate change in a tallgrass prairie in Oklahoma, USA. Infrared heaters were used to elevate temperature about 2 °C since November 1999. Annual clipping was used to mimic hay harvest. Our results showed that experimental warming significantly increased soil respiration approximately from 10% in the first 7 years (2000-2006) to 30% in the next 6 years (2007-2012). The two-stage warming stimulation of soil respiration was closely related to warming-induced increases in ecosystem production over the years. Moreover, we found that across the 13 years, warming-induced increases in soil respiration were positively affected by the proportion of aboveground net primary production (ANPP) contributed by C3 forbs. Functional composition of the plant community regulated warming-induced increases in soil respiration through the quantity and quality of organic matter inputs to soil and the amount of photosynthetic carbon (C) allocated belowground. Clipping, the interaction of clipping with warming, and warming-induced changes in soil temperature and moisture all had little effect on soil respiration over the years (all P > 0.05). Our results suggest that climate warming may drive an increase in soil respiration through altering composition of plant communities in grassland ecosystems. © 2015 John Wiley & Sons Ltd.

  20. Calcium oxalate druses affect leaf optical properties in selenium-treated Fagopyrum tataricum.

    Science.gov (United States)

    Golob, Aleksandra; Stibilj, Vekoslava; Nečemer, Marijan; Kump, Peter; Kreft, Ivan; Hočevar, Anja; Gaberščik, Alenka; Germ, Mateja

    2018-03-01

    Plants of the genus Fagopyrum contain high levels of crystalline calcium oxalate (CaOx) deposits, or druses, that can affect the leaf optical properties. As selenium has been shown to modify the uptake and accumulation of metabolically important elements such as calcium, we hypothesised that the numbers of druses can be altered by selenium treatment, and this would affect the leaf optical properties. Tartary buckwheat (Fagopyrum tataricum Gaertn.) was grown outdoors in an experimental field. At the beginning of flowering, plants were foliarly sprayed with sodium selenate solution at 10 mg selenium L -1 or only with water. Plant morphological, biochemical, physiological and optical properties were examined, along with leaf elemental composition and content. Se spraying did not affect leaf biochemical and functional properties. However, it increased leaf thickness and the contents of Se in the leaves, and decreased the density of calcium oxalate druses in the leaves. Except Se content, Se spraying did not affect contents of other elements in leaves, including total calcium per dry mass of leaf tissue. Redundancy analysis showed that of all parameters tested, only the calcium oxalate druses parameters were significant in explaining the variability of the leaf reflectance and transmittance spectra. The density of CaOx druses positively correlated with the reflectance in the blue, green, yellow and UV-B regions of the spectrum, while the area of CaOx druses per mm 2 of leaf transection area positively correlated with the transmittance in the green and yellow regions of the spectrum. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Classification of soil respiration in areas of sugarcane renewal using decision tree

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    Camila Viana Vieira Farhate

    Full Text Available ABSTRACT: The use of data mining is a promising alternative to predict soil respiration from correlated variables. Our objective was to build a model using variable selection and decision tree induction to predict different levels of soil respiration, taking into account physical, chemical and microbiological variables of soil as well as precipitation in renewal of sugarcane areas. The original dataset was composed of 19 variables (18 independent variables and one dependent (or response variable. The variable-target refers to soil respiration as the target classification. Due to a large number of variables, a procedure for variable selection was conducted to remove those with low correlation with the variable-target. For that purpose, four approaches of variable selection were evaluated: no variable selection, correlation-based feature selection (CFS, chisquare method (χ2 and Wrapper. To classify soil respiration, we used the decision tree induction technique available in the Weka software package. Our results showed that data mining techniques allow the development of a model for soil respiration classification with accuracy of 81 %, resulting in a knowledge base composed of 27 rules for prediction of soil respiration. In particular, the wrapper method for variable selection identified a subset of only five variables out of 18 available in the original dataset, and they had the following order of influence in determining soil respiration: soil temperature > precipitation > macroporosity > soil moisture > potential acidity.

  2. Soil respiration in different agricultural and natural ecosystems in an arid region.

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    Liming Lai

    Full Text Available The variation of different ecosystems on the terrestrial carbon balance is predicted to be large. We investigated a typical arid region with widespread saline/alkaline soils, and evaluated soil respiration of different agricultural and natural ecosystems. Soil respiration for five ecosystems together with soil temperature, soil moisture, soil pH, soil electric conductivity and soil organic carbon content were investigated in the field. Comparing with the natural ecosystems, the mean seasonal soil respiration rates of the agricultural ecosystems were 96%-386% higher and agricultural ecosystems exhibited lower CO(2 absorption by the saline/alkaline soil. Soil temperature and moisture together explained 48%, 86%, 84%, 54% and 54% of the seasonal variations of soil respiration in the five ecosystems, respectively. There was a significant negative relationship between soil respiration and soil electrical conductivity, but a weak correlation between soil respiration and soil pH or soil organic carbon content. Our results showed that soil CO(2 emissions were significantly different among different agricultural and natural ecosystems, although we caution that this was an observational, not manipulative, study. Temperature at the soil surface and electric conductivity were the main driving factors of soil respiration across the five ecosystems. Care should be taken when converting native vegetation into cropland from the point of view of greenhouse gas emissions.

  3. Automated Leaf Tracking using Multi-view Image Sequences of Maize Plants for Leaf-growth Monitoring

    Science.gov (United States)

    Das Choudhury, S.; Awada, T.; Samal, A.; Stoerger, V.; Bashyam, S.

    2017-12-01

    Extraction of phenotypes with botanical importance by analyzing plant image sequences has the desirable advantages of non-destructive temporal phenotypic measurements of a large number of plants with little or no manual intervention in a relatively short period of time. The health of a plant is best interpreted by the emergence timing and temporal growth of individual leaves. For automated leaf growth monitoring, it is essential to track each leaf throughout the life cycle of the plant. Plants are constantly changing organisms with increasing complexity in architecture due to variations in self-occlusions and phyllotaxy, i.e., arrangements of leaves around the stem. The leaf cross-overs pose challenges to accurately track each leaf using single view image sequence. Thus, we introduce a novel automated leaf tracking algorithm using a graph theoretic approach by multi-view image sequence analysis based on the determination of leaf-tips and leaf-junctions in the 3D space. The basis of the leaf tracking algorithm is: the leaves emerge using bottom-up approach in the case of a maize plant, and the direction of leaf emergence strictly alternates in terms of direction. The algorithm involves labeling of the individual parts of a plant, i.e., leaves and stem, following graphical representation of the plant skeleton, i.e., one-pixel wide connected line obtained from the binary image. The length of the leaf is measured by the number of pixels in the leaf skeleton. To evaluate the performance of the algorithm, a benchmark dataset is indispensable. Thus, we publicly release University of Nebraska-Lincoln Component Plant Phenotyping dataset-2 (UNL-CPPD-2) consisting of images of the 20 maize plants captured by visible light camera of the Lemnatec Scanalyzer 3D high throughout plant phenotyping facility once daily for 60 days from 10 different views. The dataset is aimed to facilitate the development and evaluation of leaf tracking algorithms and their uniform comparisons.

  4. Plant physiology and proteomics reveals the leaf response to drought in alfalfa (Medicago sativa L.).

    Science.gov (United States)

    Aranjuelo, Iker; Molero, Gemma; Erice, Gorka; Avice, Jean Christophe; Nogués, Salvador

    2011-01-01

    Despite its relevance, protein regulation, metabolic adjustment, and the physiological status of plants under drought is not well understood in relation to the role of nitrogen fixation in nodules. In this study, nodulated alfalfa plants were exposed to drought conditions. The study determined the physiological, metabolic, and proteomic processes involved in photosynthetic inhibition in relation to the decrease in nitrogenase (N(ase)) activity. The deleterious effect of drought on alfalfa performance was targeted towards photosynthesis and N(ase) activity. At the leaf level, photosynthetic inhibition was mainly caused by the inhibition of Rubisco. The proteomic profile and physiological measurements revealed that the reduced carboxylation capacity of droughted plants was related to limitations in Rubisco protein content, activation state, and RuBP regeneration. Drought also decreased amino acid content such as asparagine, and glutamic acid, and Rubisco protein content indicating that N availability limitations were caused by N(ase) activity inhibition. In this context, drought induced the decrease in Rubisco binding protein content at the leaf level and proteases were up-regulated so as to degrade Rubisco protein. This degradation enabled the reallocation of the Rubisco-derived N to the synthesis of amino acids with osmoregulant capacity. Rubisco degradation under drought conditions was induced so as to remobilize Rubisco-derived N to compensate for the decrease in N associated with N(ase) inhibition. Metabolic analyses showed that droughted plants increased amino acid (proline, a major compound involved in osmotic regulation) and soluble sugar (D-pinitol) levels to contribute towards the decrease in osmotic potential (Ψ(s)). At the nodule level, drought had an inhibitory effect on N(ase) activity. This decrease in N(ase) activity was not induced by substrate shortage, as reflected by an increase in total soluble sugars (TSS) in the nodules. Proline accumulation

  5. Oxygen and carbon isotopic compositions of gases respired by humans

    International Nuclear Information System (INIS)

    Epstein, S.; Zeiri, L.

    1988-01-01

    Oxygen-isotope fractionation associated with respiration in human individuals at rest is linearly related to the fraction of the O 2 utilized in the respiration process. The slope of this relationship is affected by a history of smoking, by vigorous exercise, and by the N 2 /O 2 ratio of the inhaled gas. For patients who suffer anemia-related diseases, the slope of this relationship is directly proportional to their level of hemoglobin. These results introduce a new approach for studying the mechanisms of O 2 consumption in human respiration and how they are affected by related diseases

  6. Effects of simulated acid rain on soil respiration and its components in a subtropical mixed conifer and broadleaf forest in southern China.

    Science.gov (United States)

    Liang, Guohua; Hui, Dafeng; Wu, Xiaoying; Wu, Jianping; Liu, Juxiu; Zhou, Guoyi; Zhang, Deqiang

    2016-02-01

    Soil respiration is a major pathway in the global carbon cycle and its response to environmental changes is an increasing concern. Here we explored how total soil respiration (RT) and its components respond to elevated acid rain in a mixed conifer and broadleaf forest, one of the major forest types in southern China. RT was measured twice a month in the first year under four treatment levels of simulated acid rain (SAR: CK, the local lake water, pH 4.7; T1, water pH 4.0; T2, water pH 3.25; and T3, water pH 2.5), and in the second year, RT, litter-free soil respiration (RS), and litter respiration (RL) were measured simultaneously. The results indicated that the mean rate of RT was 2.84 ± 0.20 μmol CO2 m(-2) s(-1) in the CK plots, and RS and RL contributed 60.7% and 39.3% to RT, respectively. SAR marginally reduced (P = 0.08) RT in the first year, but significantly reduced RT and its two components in the second year (P rain, the decline trend of RT in the forests in southern China appears to be attributable to the decline of soil respiration in the litter layer.

  7. Respiration climacteric in tomato fruits elucidated by constraint-based modelling.

    Science.gov (United States)

    Colombié, Sophie; Beauvoit, Bertrand; Nazaret, Christine; Bénard, Camille; Vercambre, Gilles; Le Gall, Sophie; Biais, Benoit; Cabasson, Cécile; Maucourt, Mickaël; Bernillon, Stéphane; Moing, Annick; Dieuaide-Noubhani, Martine; Mazat, Jean-Pierre; Gibon, Yves

    2017-03-01

    Tomato is a model organism to study the development of fleshy fruit including ripening initiation. Unfortunately, few studies deal with the brief phase of accelerated ripening associated with the respiration climacteric because of practical problems involved in measuring fruit respiration. Because constraint-based modelling allows predicting accurate metabolic fluxes, we investigated the respiration and energy dissipation of fruit pericarp at the breaker stage using a detailed stoichiometric model of the respiratory pathway, including alternative oxidase and uncoupling proteins. Assuming steady-state, a metabolic dataset was transformed into constraints to solve the model on a daily basis throughout tomato fruit development. We detected a peak of CO 2 released and an excess of energy dissipated at 40 d post anthesis (DPA) just before the onset of ripening coinciding with the respiration climacteric. We demonstrated the unbalanced carbon allocation with the sharp slowdown of accumulation (for syntheses and storage) and the beginning of the degradation of starch and cell wall polysaccharides. Experiments with fruits harvested from plants cultivated under stress conditions confirmed the concept. We conclude that modelling with an accurate metabolic dataset is an efficient tool to bypass the difficulty of measuring fruit respiration and to elucidate the underlying mechanisms of ripening. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  8. Exposure to inhalable, respirable, and ultrafine particles in welding fume.

    Science.gov (United States)

    Lehnert, Martin; Pesch, Beate; Lotz, Anne; Pelzer, Johannes; Kendzia, Benjamin; Gawrych, Katarzyna; Heinze, Evelyn; Van Gelder, Rainer; Punkenburg, Ewald; Weiss, Tobias; Mattenklott, Markus; Hahn, Jens-Uwe; Möhlmann, Carsten; Berges, Markus; Hartwig, Andrea; Brüning, Thomas

    2012-07-01

    This investigation aims to explore determinants of exposure to particle size-specific welding fume. Area sampling of ultrafine particles (UFP) was performed at 33 worksites in parallel with the collection of respirable particles. Personal sampling of respirable and inhalable particles was carried out in the breathing zone of 241 welders. Median mass concentrations were 2.48 mg m(-3) for inhalable and 1.29 mg m(-3) for respirable particles when excluding 26 users of powered air-purifying respirators (PAPRs). Mass concentrations were highest when flux-cored arc welding (FCAW) with gas was applied (median of inhalable particles: 11.6 mg m(-3)). Measurements of particles were frequently below the limit of detection (LOD), especially inside PAPRs or during tungsten inert gas welding (TIG). However, TIG generated a high number of small particles, including UFP. We imputed measurements welding fume. Concentrations were mainly predicted by the welding process and were significantly higher when local exhaust ventilation (LEV) was inefficient or when welding was performed in confined spaces. Substitution of high-emission techniques like FCAW, efficient LEV, and using PAPRs where applicable can reduce exposure to welding fume. However, harmonizing the different exposure metrics for UFP (as particle counts) and for the respirable or inhalable fraction of the welding fume (expressed as their mass) remains challenging.

  9. Sustained stimulation of soil respiration after 10 years of experimental warming

    International Nuclear Information System (INIS)

    Reth, S; Graf, W; Reichstein, M; Munch, J C

    2009-01-01

    A number of forest and grassland studies indicated that stimulation of the soil respiration by soil warming ceases after a couple of years (Luo et al 2001 Nature 413 622-5). Here we present results from a long-term soil warming lysimeter experiment in southern Germany showing sustained stimulation of soil respiration after 10 years. Moreover, both warmed and control treatments exhibited a similar temperature response of soil respiration, indicating that adaptation in terms of temperature sensitivity was absent. Carbon dioxide concentration measurements within the profiles are supporting these findings. The increased soil respiration occurred although vegetation productivity in the warmed treatment was not higher than in the control plots. These findings strongly contrast with current soil carbon modeling concepts, where carbon pools decay according to first-order kinetics, and thus a depletion of labile soil carbon pools leads to an apparent down-regulation of microbial respiration (Knorr et al 2005 Nature 433 298-301). Consequently, the potential for positive climate carbon cycle feedback may be larger than represented in current models of soil carbon turnover.

  10. Measurement and Modeling of Respiration Rate of Tomato (Cultivar Roma) for Modified Atmosphere Storage.

    Science.gov (United States)

    Kandasamy, Palani; Moitra, Ranabir; Mukherjee, Souti

    2015-01-01

    Experiments were conducted to determine the respiration rate of tomato at 10, 20 and 30 °C using closed respiration system. Oxygen depletion and carbon dioxide accumulation in the system containing tomato was monitored. Respiration rate was found to decrease with increasing CO2 and decreasing O2 concentration. Michaelis-Menten type model based on enzyme kinetics was evaluated using experimental data generated for predicting the respiration rate. The model parameters that obtained from the respiration rate at different O2 and CO2 concentration levels were used to fit the model against the storage temperatures. The fitting was fair (R2 = 0.923 to 0.970) when the respiration rate was expressed as O2 concentation. Since inhibition constant for CO2 concentration tended towards negetive, the model was modified as a function of O2 concentration only. The modified model was fitted to the experimental data and showed good agreement (R2 = 0.998) with experimentally estimated respiration rate.

  11. Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis

    Science.gov (United States)

    Smith, Jeffrey D.; MacDougall, Colin C.; Johnstone, Jennie; Copes, Ray A.; Schwartz, Brian; Garber, Gary E.

    2016-01-01

    Background: Conflicting recommendations exist related to which facial protection should be used by health care workers to prevent transmission of acute respiratory infections, including pandemic influenza. We performed a systematic review of both clinical and surrogate exposure data comparing N95 respirators and surgical masks for the prevention of transmissible acute respiratory infections. Methods: We searched various electronic databases and the grey literature for relevant studies published from January 1990 to December 2014. Randomized controlled trials (RCTs), cohort studies and case–control studies that included data on health care workers wearing N95 respirators and surgical masks to prevent acute respiratory infections were included in the meta-analysis. Surrogate exposure studies comparing N95 respirators and surgical masks using manikins or adult volunteers under simulated conditions were summarized separately. Outcomes from clinical studies were laboratory-confirmed respiratory infection, influenza-like illness and workplace absenteeism. Outcomes from surrogate exposure studies were filter penetration, face-seal leakage and total inward leakage. Results: We identified 6 clinical studies (3 RCTs, 1 cohort study and 2 case–control studies) and 23 surrogate exposure studies. In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection (RCTs: odds ratio [OR] 0.89, 95% confidence interval [CI] 0.64–1.24; cohort study: OR 0.43, 95% CI 0.03–6.41; case–control studies: OR 0.91, 95% CI 0.25–3.36); (b) influenza-like illness (RCTs: OR 0.51, 95% CI 0.19–1.41); or (c) reported workplace absenteeism (RCT: OR 0.92, 95% CI 0.57–1.50). In the surrogate exposure studies, N95 respirators were associated with less filter penetration, less face-seal leakage and less total inward leakage under laboratory experimental conditions

  12. Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis.

    Science.gov (United States)

    Smith, Jeffrey D; MacDougall, Colin C; Johnstone, Jennie; Copes, Ray A; Schwartz, Brian; Garber, Gary E

    2016-05-17

    Conflicting recommendations exist related to which facial protection should be used by health care workers to prevent transmission of acute respiratory infections, including pandemic influenza. We performed a systematic review of both clinical and surrogate exposure data comparing N95 respirators and surgical masks for the prevention of transmissible acute respiratory infections. We searched various electronic databases and the grey literature for relevant studies published from January 1990 to December 2014. Randomized controlled trials (RCTs), cohort studies and case-control studies that included data on health care workers wearing N95 respirators and surgical masks to prevent acute respiratory infections were included in the meta-analysis. Surrogate exposure studies comparing N95 respirators and surgical masks using manikins or adult volunteers under simulated conditions were summarized separately. Outcomes from clinical studies were laboratory-confirmed respiratory infection, influenza-like illness and workplace absenteeism. Outcomes from surrogate exposure studies were filter penetration, face-seal leakage and total inward leakage. We identified 6 clinical studies (3 RCTs, 1 cohort study and 2 case-control studies) and 23 surrogate exposure studies. In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection (RCTs: odds ratio [OR] 0.89, 95% confidence interval [CI] 0.64-1.24; cohort study: OR 0.43, 95% CI 0.03-6.41; case-control studies: OR 0.91, 95% CI 0.25-3.36); (b) influenza-like illness (RCTs: OR 0.51, 95% CI 0.19-1.41); or (c) reported workplace absenteeism (RCT: OR 0.92, 95% CI 0.57-1.50). In the surrogate exposure studies, N95 respirators were associated with less filter penetration, less face-seal leakage and less total inward leakage under laboratory experimental conditions, compared with surgical masks. Although N95

  13. Pinus sylvestris switches respiration substrates under shading but not during drought

    Science.gov (United States)

    Hartmann, Henrik; Fischer, Sarah; Hanf, Stefan; Frosch, Torsten; Poppp, Jürgen; Trumbore, Susan

    2015-04-01

    Reduced carbon assimilation during prolonged drought forces trees to rely on stored carbon to maintain vital processes like respiration. It has been shown, however, that the use of carbohydrates, a major carbon storage pool and main respiratory substrate in plants, strongly declines with deceasing plant hydration. Yet, no empirical evidence has been produced to what degree other carbon storage compounds like lipids and proteins may fuel respiration during drought. We exposed young scots pine trees to carbon limitation using either drought or shading and assessed respiratory substrate use by monitoring the respiratory quotient, δ13C of respired CO2and concentrations of the major storage compounds, i.e. carbohydrates (COH), lipids and amino acids. Generally, respiration was dominated by the most abundant substrate. Only shaded trees shifted from carbohydrate-dominated to lipid-dominated respiration and showed progressive carbohydrate depletion. In drought trees respiration was strongly reduced and fueled with carbohydrates from also strongly reduced carbon assimilation. Initial COH content was maintained during drought probably due to reduced COH mobilization and use and the maintained COH content may have prevented lipid catabolism via sugar signaling. Our results suggest that respiratory substrates other than carbohydrates are used under carbohydrate limitation but not during drought. Thus, respiratory substrate change cannot provide an efficient means to counterbalance carbon limitation under natural drought.

  14. Evaluation of dried vegetables residues for poultry: II. Effects of feeding cabbage leaf residues on broiler performance, ileal digestibility and total tract nutrient digestibility.

    Science.gov (United States)

    Mustafa, A F; Baurhoo, B

    2017-03-01

    A study was conducted to investigate the effects of partial replacing corn and soybean meal with dried cabbage leaf residues (DCR) on broiler growth performance, apparent ileal nutrient digestibility, and apparent total tract nutrient utilization. Dietary treatments include 4 levels of DCR (0, 3, 6, and 9%). Two hundred and twenty-four day-old male broilers were randomly assigned to one of 4 groups (8 cage replicates; 7 birds/cage) and grown over a 35-d experimental period. Results showed that feeding DCR had no effects on daily body weigh gain (average 53.4 g/d), daily feed intake (average 94.9 g/d), and feed conversion ratio (average 1.78 g of feed/g of gain). Inclusion of DCR reduced apparent ileal DM (quadratic effect, P digestibility of younger birds (d 21) while incremental levels of DCR had no effect on apparent ileal nutrient digestibilities of older birds (d 35). Apparent total tract digestibility of DM, OM, and CP increased (linear effect, P digestibility of older birds and improved apparent total tract nutrient digestibility. © 2016 Poultry Science Association Inc.

  15. Effects of dietary sweet potato leaf meal on the growth, non-specific immune responses, total phenols and antioxidant capacity in channel catfish (Ictalurus punctatus).

    Science.gov (United States)

    Lochmann, Rebecca T; Islam, Shahidul; Phillips, Harold; Adam, Zelalem; Everette, Jace

    2013-04-01

    Traditional energy sources in catfish diets have become costly, and economical alternatives are needed. Sweet potato leaves are underutilised agricultural by-products that provide energy and substantial amounts of phenols, which affect animal and human health. There is little information on the effects of these compounds on catfish, or the capacity of catfish to accumulate dietary phenols. Catfish enriched with phenols have marketing potential as functional foods. This study investigated the effects of diets with sweet potato leaf meal (SPLM) on growth performance, health and total phenolic compounds in catfish. SPLM was substituted for wheat middlings in three diets fed to groups of juvenile catfish for 10 weeks. Weight gain, feed conversion, survival, alternative complement activity and lysozyme activity were similar among diets. Haematocrit was lower in fish fed diets with SPLM, but within the normal range. Total phenols and antioxidant capacity in the whole body were similar among treatments. SPLM was an effective energy source for catfish up to the maximum level tested (230 g kg(-1) diet). SPLM did not enhance total phenols in catfish, but there were no apparent antinutritional effects of the meal on catfish growth, health or survival. © 2012 Society of Chemical Industry.

  16. Induced resistance and gene expression in wheat against leaf rust ...

    African Journals Online (AJOL)

    uvp

    2013-05-15

    associated molecular .... Total RNA was extracted from approximately 0.1 g ground leaf tissue harvested at 0, 24, 48, 72, 96 and ... The RNA was finally dissolved in 100 µl 0.1% (v/v) DMPC treated water. Residual DNA was eliminated ...

  17. Cheyne-Stokes respiration in patients with congestive heart failure: causes and consequences.

    Science.gov (United States)

    Lorenzi-Filho, Geraldo; Genta, Pedro R; Figueiredo, Adelaide C; Inoue, Daniel

    2005-08-01

    Cheyne-Stokes respiration is a form of periodic breathing in which central apneas and hypopneas alternate with periods of hyperventilation, producing a waxing and waning pattern of tidal volume. This review focuses on the causes and consequences of Cheyne-Stokes respiration in patients with congestive heart failure, in whom the prevalence is strikingly high and ranges from 30% to 50%. Several factors have been implicated in the genesis of Cheyne-Stokes respiration, including low cardiac output and recurrent hypoxia. The key pathophysiological mechanism triggering Cheyne-Stokes respiration is hyperventilation and low arterial CO2 (PaCO2) that when below the apneic threshold triggers a central apnea. Hyperventilation is associated with pulmonary congestion, and Cheyne-Stokes respiration is more prone to occur during sleep, when the respiratory system is mainly dependent on chemical control. It is associated with recurrent dips in oxygen saturation and arousals from sleep, with oscillations in blood pressure and heart rate, sympathetic activation and increased risk of ventricular tachycardia. Cheyne-Stokes respiration is an independent marker of poor prognosis and may participate in a vicious cycle, further stressing the failing heart.

  18. Metabolic responses and β-carotene production by the unicellular green alga Dunaliella salina exposed to leaf extracts

    Directory of Open Access Journals (Sweden)

    Alireza Einali

    Full Text Available ABSTRACT The present work investigated the effects of aqueous extracts of eucalyptus ( Eucalyptus globulus and elderberry ( Sambucus ebulus leaves on β-carotene productivity in Dunaliella salina, a green microalga. Leaf extracts from eucalyptus have greater amounts of phenolics and flavonoids, as well as greater ferric reducing antioxidant potential than elderberry. The extracts of both species greatly inhibited growth of algal suspensions. However, chlorophyll and β-carotene concentration increased in cells treated with leaf extracts, and the highest values were detected in 1 % eucalyptus and 2 % elderberry extracts. Fresh weight, total sugar, and protein content significantly increased following exposure of cells to different doses of leaf extracts. However, in doses containing more than 2 % eucalyptus, the upward trend for total sugar and protein ceased and remained statistically unchanged. These results suggest that metabolic modifications enable D. salina cells to tolerate the stress induced by the leaf extracts through allocating carbon flux to the synthesis of osmolytes and putative antioxidant molecules (e.g. sugars and β-carotene. Therefore, the use of leaf extracts holds potential to be a promising and effective way to improve D. salina cultivation for β-carotene production and other biotechnological and industrial applications.

  19. Forest floor and mineral soil respiration rates in a northern Minnesota red pine chronosequence

    Science.gov (United States)

    Powers, Matthew; Kolka, Randall; Bradford, John B.; Palik, Brian J.; Jurgensen, Martin

    2018-01-01

    We measured total soil CO2 efflux (RS) and efflux from the forest floor layers (RFF) in red pine (Pinus resinosaAit.) stands of different ages to examine relationships between stand age and belowground C cycling. Soil temperature and RS were often lower in a 31-year-old stand (Y31) than in 9-year-old (Y9), 61-year-old (Y61), or 123-year-old (Y123) stands. This pattern was most apparent during warm summer months, but there were no consistent differences in RFF among different-aged stands. RFF represented an average of 4–13% of total soil respiration, and forest floor removal increased moisture content in the mineral soil. We found no evidence of an age effect on the temperature sensitivity of RS, but respiration rates in Y61 and Y123 were less sensitive to low soil moisture than RS in Y9 and Y31. Our results suggest that soil respiration’s sensitivity to soil moisture may change more over the course of stand development than its sensitivity to soil temperature in red pine, and that management activities that alter landscape-scale age distributions in red pine forests could have significant impacts on rates of soil CO2 efflux from this forest type.

  20. Seasonal Oxygen Dynamics in a Warm Temperate Estuary: Effects of Hydrologic Variability on Measurements of Primary Production, Respiration, and Net Metabolism

    Science.gov (United States)

    Seasonal responses in estuarine metabolism (primary production, respiration, and net metabolism) were examined using two complementary approaches. Total ecosystem metabolism rates were calculated from dissolved oxygen time series using Odum’s open water method. Water column rates...

  1. Inhibitory Effects of Respiration Inhibitors on Aflatoxin Production

    Directory of Open Access Journals (Sweden)

    Shohei Sakuda

    2014-03-01

    Full Text Available Aflatoxin production inhibitors, which do not inhibit the growth of aflatoxigenic fungi, may be used to control aflatoxin without incurring a rapid spread of resistant strains. A respiration inhibitor that inhibits aflatoxin production was identified during a screening process for natural, aflatoxin-production inhibitors. This prompted us to evaluate respiration inhibitors as potential aflatoxin control agents. The inhibitory activities of four natural inhibitors, seven synthetic miticides, and nine synthetic fungicides were evaluated on aflatoxin production in Aspergillus parasiticus. All of the natural inhibitors (rotenone, siccanin, aptenin A5, and antimycin A inhibited fungal aflatoxin production with IC50 values around 10 µM. Among the synthetic miticides, pyridaben, fluacrypyrim, and tolfenpyrad exhibited strong inhibitory activities with IC50 values less than 0.2 µM, whereas cyflumetofen did not show significant inhibitory activity. Of the synthetic fungicides, boscalid, pyribencarb, azoxystrobin, pyraclostrobin, and kresoxim-methyl demonstrated strong inhibitory activities, with IC50 values less than 0.5 µM. Fungal growth was not significantly affected by any of the inhibitors tested at concentrations used. There was no correlation observed between the targets of respiration inhibitors (complexes I, II, and III and their IC50 values for aflatoxin-production inhibitory activity. This study suggests that respiration inhibitors, including commonly used pesticides, are useful for aflatoxin control.

  2. Inhibitory Effects of Respiration Inhibitors on Aflatoxin Production

    Science.gov (United States)

    Sakuda, Shohei; Prabowo, Diyan Febri; Takagi, Keiko; Shiomi, Kazuro; Mori, Mihoko; Ōmura, Satoshi; Nagasawa, Hiromichi

    2014-01-01

    Aflatoxin production inhibitors, which do not inhibit the growth of aflatoxigenic fungi, may be used to control aflatoxin without incurring a rapid spread of resistant strains. A respiration inhibitor that inhibits aflatoxin production was identified during a screening process for natural, aflatoxin-production inhibitors. This prompted us to evaluate respiration inhibitors as potential aflatoxin control agents. The inhibitory activities of four natural inhibitors, seven synthetic miticides, and nine synthetic fungicides were evaluated on aflatoxin production in Aspergillus parasiticus. All of the natural inhibitors (rotenone, siccanin, aptenin A5, and antimycin A) inhibited fungal aflatoxin production with IC50 values around 10 µM. Among the synthetic miticides, pyridaben, fluacrypyrim, and tolfenpyrad exhibited strong inhibitory activities with IC50 values less than 0.2 µM, whereas cyflumetofen did not show significant inhibitory activity. Of the synthetic fungicides, boscalid, pyribencarb, azoxystrobin, pyraclostrobin, and kresoxim-methyl demonstrated strong inhibitory activities, with IC50 values less than 0.5 µM. Fungal growth was not significantly affected by any of the inhibitors tested at concentrations used. There was no correlation observed between the targets of respiration inhibitors (complexes I, II, and III) and their IC50 values for aflatoxin-production inhibitory activity. This study suggests that respiration inhibitors, including commonly used pesticides, are useful for aflatoxin control. PMID:24674936

  3. Genetic diversity of flavonoid content in leaf of hawthorn resources

    International Nuclear Information System (INIS)

    Zhao, Y.; Wang, G.; Liu, Z.

    2014-01-01

    Hawthorn (Cratageus spp.) are important medicinal plants. Flavonoids are the main active ingredient in hawthorn. With the help of hawthorn leaf flavonoids efficient detection system, vitexin, rhamnosylvitexin, hyperin, rutin and quercetin of 122 hawthorn resources was precisely measured.The flavonoid contents of 10 hawthorn species were explicited. The comparation of flavonoids revealed the abundant genetic diversity of hawthorn flavones. Large variable coefficient has been observed among 5 flavonoid monomer traits. The coefficients of variation were 44.17%, 132.2%, 157.08%, 113.91% and 31.05 for Vitexin, Rhamnosylvitexin, Hyperoside, Rutin and Quercetin respectively. The sum of these 5 flavonoid monomer contents represented the total flavonoids in hawthorn. The total coefficients of variation was 44.01%. Some high-content-flavone and valuable leaf resources were found. This research could provide accurate date for further production, breeding and the effective use of medicinal resources. (author)

  4. Effects of long-term microgravitation exposure on cell respiration of the rat musculus soleus fibers.

    Science.gov (United States)

    Veselova, O M; Ogneva, I V; Larina, I M

    2011-07-01

    Cell respiration of the m. soleus fibers was studied in Wistar rats treated with succinic acid and exposed to microgravitation for 35 days. The results indicated that respiration rates during utilization of endogenous and exogenous substrates and the maximum respiration rate decreased in animals subjected to microgravitation without succinate treatment. The respiration rate during utilization of exogenous substrate did not increase in comparison with that on endogenous substrates. Succinic acid prevented the decrease in respiration rate on endogenous substrates and the maximum respiration rate. On the other hand, the respiration rate on exogenous substrates was reduced in vivarium control rats receiving succinate in comparison with intact control group. That could indicate changed efficiency of complex I of the respiratory chain due to reciprocal regulation of the tricarbonic acid cycle.

  5. Use of Facemasks and Respirators

    Centers for Disease Control (CDC) Podcasts

    2007-05-15

    This program demonstrates the differences of facemasks and respirators that are to be used in public settings during an influenza pandemic.  Created: 5/15/2007 by CDC, National Institute for Occupational Safety and Health (NIOSH).   Date Released: 5/25/2007.

  6. Characterization of the respiration-induced yeast mitochondrial permeability transition pore.

    Science.gov (United States)

    Bradshaw, Patrick C; Pfeiffer, Douglas R

    2013-12-01

    When isolated mitochondria from the yeast Saccharomyces cerevisiae oxidize respiratory substrates in the absence of phosphate and ADP, the yeast mitochondrial unselective channel, also called the yeast permeability transition pore (yPTP), opens in the inner membrane, dissipating the electrochemical gradient. ATP also induces yPTP opening. yPTP opening allows mannitol transport into isolated mitochondria of laboratory yeast strains, but mannitol is not readily permeable through the yPTP in an industrial yeast strain, Yeast Foam. The presence of oligomycin, an inhibitor of ATP synthase, allowed for respiration-induced mannitol permeability in mitochondria from this strain. Potassium (K+) had varied effects on the respiration-induced yPTP, depending on the concentration of the respiratory substrate added. At low respiratory substrate concentrations K+ inhibited respiration-induced yPTP opening, while at high substrate concentrations this effect diminished. However, at the high respiratory substrate concentrations, the presence of K+ partially prevented phosphate inhibition of yPTP opening. Phosphate was found to inhibit respiration-induced yPTP opening by binding a site on the matrix space side of the inner membrane in addition to its known inhibitory effect of donating protons to the matrix space to prevent the pH change necessary for yPTP opening. The respiration-induced yPTP was also inhibited by NAD, Mg2+, NH4 + or the oxyanion vanadate polymerized to decavanadate. The results demonstrate similar effectors of the respiration-induced yPTP as those previously described for the ATP-induced yPTP and reconcile previous strain-dependent differences in yPTP solute selectivity. Copyright © 2013 John Wiley & Sons, Ltd.

  7. Geometric leaf placement strategies

    International Nuclear Information System (INIS)

    Fenwick, J D; Temple, S W P; Clements, R W; Lawrence, G P; Mayles, H M O; Mayles, W P M

    2004-01-01

    Geometric leaf placement strategies for multileaf collimators (MLCs) typically involve the expansion of the beam's-eye-view contour of a target by a uniform MLC margin, followed by movement of the leaves until some point on each leaf end touches the expanded contour. Film-based dose-distribution measurements have been made to determine appropriate MLC margins-characterized through an index d 90 -for multileaves set using one particular strategy to straight lines lying at various angles to the direction of leaf travel. Simple trigonometric relationships exist between different geometric leaf placement strategies and are used to generalize the results of the film work into d 90 values for several different strategies. Measured d 90 values vary both with angle and leaf placement strategy. A model has been derived that explains and describes quite well the observed variations of d 90 with angle. The d 90 angular variations of the strategies studied differ substantially, and geometric and dosimetric reasoning suggests that the best strategy is the one with the least angular variation. Using this criterion, the best straightforwardly implementable strategy studied is a 'touch circle' approach for which semicircles are imagined to be inscribed within leaf ends, the leaves being moved until the semicircles just touch the expanded target outline

  8. Antimony Redox Biotransformation in the Subsurface: Effect of Indigenous Sb(V) Respiring Microbiota.

    Science.gov (United States)

    Wang, Liying; Ye, Li; Yu, Yaqin; Jing, Chuanyong

    2018-02-06

    Anaerobic microbiological antimonate [Sb(V)] respiration is a newly discovered process regulating the Sb redox transformation in soils. However, little is known about the role microbiological Sb(V) respiration plays in the fate of Sb in the subsurface, especially in the presence of sulfate and electron shuttles. Herein, we successfully enriched a Sb(V) reducing microbiota (SbRM) from the subsurface near an active Sb mine. SbRM was dominated by genus Alkaliphilus (18-36%), Clostridiaceae (17-18%), Tissierella (24-27%), and Lysinibacillus (16-37%). The incubation results showed that SbRM reduced 88% of dissolved Sb(V) to Sb(III), but the total Sb mobility remained the same as in the abiotic control, indicating that SbRM alone did not increase the total Sb release but regulated the Sb speciation in the subsurface. Micro X-ray fluorescence (μ-XRF) analysis suggested the association of Sb and Fe, and electron shuttles such as anthraquinone-2,6-disulfonic disodium salt (AQDS) markedly enhanced the Sb release due to its ability to facilitate Fe mineral dissolution. Sb L-edge and S K-edge X-ray absorption near edge structure (XANES) results demonstrated that indigenous SbRM immobilized Sb via Sb 2 S 3 formation, especially in a sulfur-rich environment. The insights gained from this study shed new light on Sb mobilization and its risk assessment in the subsurface environment.

  9. Molecular mapping and improvement of leaf rust resistance in wheat breeding lines.

    Science.gov (United States)

    Tsilo, Toi J; Kolmer, James A; Anderson, James A

    2014-08-01

    Leaf rust, caused by Puccinia triticina, is the most common and widespread disease of wheat (Triticum aestivum) worldwide. Deployment of host-plant resistance is one of the strategies to reduce losses due to leaf rust disease. The objective of this study was to map genes for adult-plant resistance to leaf rust in a recombinant inbred line (RIL) population originating from MN98550-5/MN99394-1. The mapping population of 139 RILs and five checks were evaluated in 2005, 2009, and 2010 in five environments. Natural infection occurred in the 2005 trials and trials in 2009 and 2010 were inoculated with leaf rust. Four quantitative trait loci (QTL) on chromosomes 2BS, 2DS, 7AL, and 7DS were detected. The QTL on 2BS explained up to 33.6% of the phenotypic variation in leaf rust response, whereas the QTL on 2DS, 7AL, and 7DS explained up to 15.7, 8.1, and 34.2%, respectively. Seedling infection type tests conducted with P. triticina races BBBD and SBDG confirmed that the QTL on 2BS and 2DS were Lr16 and Lr2a, respectively, and these genes were expressed in the seedling and field plot tests. The Lr2a gene mapped at the same location as Sr6. The QTL on 7DS was Lr34. The QTL on 7AL is a new QTL for leaf rust resistance. The joint effects of all four QTL explained 74% of the total phenotypic variation in leaf rust severity. Analysis of different combinations of QTL showed that the RILs containing all four or three of the QTL had the lowest average leaf rust severity in all five environments. Deployment of these QTL in combination or with other effective genes will lead to successful control of leaf rust.

  10. Dynamics of enhanced mitochondrial respiration in female compared with male rat cerebral arteries.

    Science.gov (United States)

    Rutkai, Ibolya; Dutta, Somhrita; Katakam, Prasad V; Busija, David W

    2015-11-01

    Mitochondrial respiration has never been directly examined in intact cerebral arteries. We tested the hypothesis that mitochondrial energetics of large cerebral arteries ex vivo are sex dependent. The Seahorse XFe24 analyzer was used to examine mitochondrial respiration in isolated cerebral arteries from adult male and female Sprague-Dawley rats. We examined the role of nitric oxide (NO) on mitochondrial respiration under basal conditions, using N(ω)-nitro-l-arginine methyl ester, and following pharmacological challenge using diazoxide (DZ), and also determined levels of mitochondrial and nonmitochondrial proteins using Western blot, and vascular diameter responses to DZ. The components of mitochondrial respiration including basal respiration, ATP production, proton leak, maximal respiration, and spare respiratory capacity were elevated in females compared with males, but increased in both male and female arteries in the presence of the NOS inhibitor. Although acute DZ treatment had little effect on mitochondrial respiration of male arteries, it decreased the respiration in female arteries. Levels of mitochondrial proteins in Complexes I-V and the voltage-dependent anion channel protein were elevated in female compared with male cerebral arteries. The DZ-induced vasodilation was greater in females than in males. Our findings show that substantial sex differences in mitochondrial respiratory dynamics exist in large cerebral arteries and may provide the mechanistic basis for observations that the female cerebral vasculature is more adaptable after injury. Copyright © 2015 the American Physiological Society.

  11. Yielding of leaf celery Apium graveolens L. var. secalinum Alef. depending on the number of harvests and irrigation

    Directory of Open Access Journals (Sweden)

    Ewa Rożek

    2013-04-01

    Full Text Available Leaf celery (Apium graveolensvar. secalinum is a vegetable with medicinal and spicy properties. Its numerous intensely fragrant leaves can be cut several times during the plant growing period. The aim of this study was to evaluate the effect of irrigation and number of harvests on leaf celery yield of the cultivars ‘Afina’ and‘Gewone Snij’. Plant irrigation significantly increased leaf yield and plant height of leaf celery. Higher total yield was obtained from non-irrigated plants when leaves were harvested three times, whereas for irrigated plants yield was higher in the case of two leaf harvests. Irrespective of the experimental factors, higher yield was obtained from the cultivar ‘Gewone Snij’.

  12. Apparent over-investment in leaf venation relaxes leaf morphological constraints on photosynthesis in arid habitats

    Science.gov (United States)

    de Boer, Hugo; Drake, Paul; Veneklaas, Erik

    2017-04-01

    The close relationship between leaf water status and stomatal conductance implies that the hydraulic architecture of leaves poses an important constraint on transpiration, specifically in arid environments with high evaporative demands. However, it remains uncertain how morphological, hydraulic and photosynthetic traits are coordinated to achieve optimal leaf functioning in arid environments. Critical is that leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy≈1. Although this theory is supported by observations on many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis we assembled leaf hydraulic, morphological and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent over-investment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf lifespan, high hydraulic and thermal capacitances, and high potential rates of leaf

  13. Delayed ultraviolet light-induced cessation of respiration by inadequate aeration of Escherichia coli

    International Nuclear Information System (INIS)

    Joshi, J.G.; Swenson, P.A.; Schenley, R.L.

    1977-01-01

    Inadequately aerated Escherichia coli B/r cultures did not shut their respiration off 60 min after ultraviolet light (52 J/m 2 at 254 nm) as they did when well supplied with oxygen. Since cessation of respiration is associated with cell death, the result suggested that oxygen toxicity by superoxide radicals generated by cell metabolism might be responsible for cell death. The specific activity of superoxide dismutase, which scavenges O 2 - radicals, increased twofold after 90 min of adequate aeration, but the specific activity of catalase remained constant. Respiration and viability of irradiated cells were affected not at all by the presence of superoxide dismutase and only slightly by the presence of catalase. Metal ions such as Mn 2+ and Fe 2+ , inducers of superoxide dismutase, had no effect on respiration and viability. When irradiated cells were incubated under N 2 for 90 min, the respiration, growth, and viability time-course responses were the same as for cells not exposed to anaerobiosis. We conclude that superoxide anions generated at the time of irradiation play no part in cessation of respiration and cell death and that inadequate aeration or anaerobiosis delays the ultraviolet light-induced synthesis of proteins responsible for the irreversible cessation of respiration

  14. Acclimation and soil moisture constrain sugar maple root respiration in experimentally warmed soil.

    Science.gov (United States)

    Jarvi, Mickey P; Burton, Andrew J

    2013-09-01

    The response of root respiration to warmer soil can affect ecosystem carbon (C) allocation and the strength of positive feedbacks between climatic warming and soil CO2 efflux. This study sought to determine whether fine-root (maple (Acer saccharum Marsh.)-dominated northern hardwood forest would adjust to experimentally warmed soil, reducing C return to the atmosphere at the ecosystem scale to levels lower than that would be expected using an exponential temperature response function. Infrared heating lamps were used to warm the soil (+4 to +5 °C) in a mature sugar maple forest in a fully factorial design, including water additions used to offset the effects of warming-induced dry soil. Fine-root-specific respiration rates, root biomass, root nitrogen (N) concentration, soil temperature and soil moisture were measured from 2009 to 2011, with experimental treatments conducted from late 2010 to 2011. Partial acclimation of fine-root respiration to soil warming occurred, with soil moisture deficit further constraining specific respiration rates in heated plots. Fine-root biomass and N concentration remained unchanged. Over the 2011 growing season, ecosystem root respiration was not significantly greater in warmed soil. This result would not be predicted by models that allow respiration to increase exponentially with temperature and do not directly reduce root respiration in drier soil.

  15. Soil Respiration Declines Following Beetle - Induced Forest Mortality in a Lodgepole Pine Forest

    Science.gov (United States)

    Borkhuu, B.; Peckham, S. D.; Norton, U.; Ewers, B. E.; Pendall, E.

    2014-12-01

    Lodgepole pine (Pinus contorta var. latifolia) forests in northern Colorado and southeast Wyoming have been undergoing a major mortality event owing to mountain pine beetle (Dendroctonus ponderosae) infestation since 2007. We studied biotic and abiotic drivers of growing season soil respiration in four mature stands experiencing different levels of mortality between 2008 and 2012 in the Medicine Bow Mountains, southeastern Wyoming, USA. For five years, beetle infestation significantly altered forest structure. Stand mortality was 30% and more than 80% in stands with the lowest and highest mortality, respectively. Understory vegetation cover increased by 50% for five years following beetle infestation. Needlefall was increased by more than 50% during first two years of beetle infestation compared to the pre-disturbance period. We did not observe an immediate increase in soil respiration following beetle infestation as suggested by some researchers. Soil respiration rates in midsummer ranged from 1.4 ± 0.1 μmol m-2 s-1 in stands with highest mortality to 3.1 ± 0.2 μmol m-2s-1 in uninfested stand. Live tree basal area was the dominant factor controlling soil respiration, explaining more than 60% of the interannual and spatial variations in response to the disturbance. In addition, soil respiration was significantly correlated with fine root biomass, which explained 55% of variations, providing strong evidence that autotrophic respiration dominated the forest soil respiration flux. Furthermore, the seasonality of soil respiration was controlled mainly by mean monthly precipitation and mid-day photosynthetically active radiation. Each factor predicted from 30% to 50% of seasonal soil respiration variability with the highest correlation coefficients in stand with the lowest mortality. Our results clearly indicate that the reduction of photosynthesis in trees over the infestation period significantly reduced soil respiration. The remaining activity in dead stands may

  16. Internal respiration of Amazon tree stems greatly exceeds external CO2 efflux

    Directory of Open Access Journals (Sweden)

    J. Q. Chambers

    2012-12-01

    Full Text Available Respiration in tree stems is an important component of forest carbon balance. The rate of CO2 efflux from the stem has often been assumed to be a measure of stem respiration. However, recent work in temperate forests has demonstrated that stem CO2 efflux can either overestimate or underestimate respiration rate because of emission or removal of CO2 by transport in xylem water. Here, we studied gas exchange from stems of tropical forest trees using a new approach to better understand respiration in an ecosystem that plays a key role in the global carbon cycle. Our main questions were (1 is internal CO2 transport important in tropical trees, and, if so, (2 does this transport result in net release of CO2 respired in the roots at the stem, or does it cause the opposite effect of net removal of stem-respired CO2? To answer these questions, we measured the ratio of stem CO2 efflux to O2 influx. This ratio, defined here as apparent respiratory quotient (ARQ, is expected to equal 1.0 if carbohydrates are the substrate for respiration, and the net transport of CO2 in the xylem water is negligible. Using a stem chamber approach to quantifying ARQ, we found values of 0.66 ± 0.18. These low ARQ values indicate that a large portion of respired CO2 (~ 35% is not emitted locally, and is probably transported upward in the stem. ARQ values of 0.21 ± 0.10 were found for the steady-state gas concentration within the stem, sampled by in-stem equilibration probes. These lower values may result from the proximity to the xylem water stream. In contrast, we found ARQ values of 1.00 ± 0.13 for soil respiration. Our results indicate the existence of a considerable internal flux of CO2 in the stems of tropical trees. If the transported CO2 is used in the canopy as a substrate for photosynthesis, it could account for up to 10% of the C fixed by the tree, and perhaps serve as a mechanism that buffers the response of the tree to changing CO2 levels. Our results also

  17. [Soil basal respiration and enzyme activities in the root-layer soil of tea bushes in a red soil].

    Science.gov (United States)

    Yu, Shen; He, Zhenli; Zhang, Rongguang; Chen, Guochao; Huang, Changyong

    2003-02-01

    Soil basal respiration potential, metabolic quotient (qCO2), and activities of urease, invertase and acid phosphomonoesterase were investigated in the root-layer of 10-, 40-, and 90-yr-old tea bushes grown on the same type of red soil. The soil daily basal respiration potential ranged from 36.23 to 58.52 mg.kg-1.d-1, and the potentials in the root-layer of 40- or 90-yr-old were greater than that of 10-yr old tea bushes. The daily qCO2, ranging from 0.30 to 0.68, was in the reverse trend. The activities of test three enzymes changed differently with tea bushes' age. Urease activity in the root-layer of all age tea bushes ranged from 41.48 to 47.72 mg.kg-1.h-1 and slightly decreased with tea bushes' age. Invertase activity was 189.29-363.40 mg.kg-1.h-1 and decreased with tea bushes' age, but its activity in the root-layer of 10-year old tea bushes was significantly greater than that in the root-layer soil of 40- or 90-year old tea bushes. Acid phosphomonoesterase activity (444.22-828.32 mg.kg-1.h-1) increased significantly with tea bushes' age. Soil basal respiration potential, qCO2 and activities of 3 soil enzymes were closely related to soil pH, soil organic carbon, total nitrogen and C/N ratio, total soluble phenol, and microbial biomass carbon, respectively.

  18. Soil respiration in tropical seasonal rain forest in Xishuangbanna, SW China

    Institute of Scientific and Technical Information of China (English)

    SHA; Liqing; ZHENG; Zheng; TANG; Jianwei; WANG; Yinghong

    2005-01-01

    With the static opaque chamber and gas chromatography technique, from January 2003 to January 2004 soil respiration was investigated in a tropical seasonal rain forest in Xishuangbanna, SW China. In this study three treatments were applied, each with three replicates: A (bare soil), B (soil+litter), and C (soil+litter+seedling). The results showed that soil respiration varied seasonally, low from December 2003 to February 2004, and high from June to July 2004. The annual average values of CO2 efflux from soil respiration differed among the treatments at 1% level, with the rank of C (14642 mgCO2· m-2. h-1)>B (12807 mgCO2· m-2. h-1)>A (9532 mgCO2· m-2. h-1). Diurnal variation in soil respiration was not apparent due to little diurnal temperate change in Xishuangbanna. There was a parabola relationship between soil respiration and soil moisture at 1% level. Soil respiration rates were higher when soil moisture ranged from 35% to 45%. There was an exponential relationship between soil respiration and soil temperature (at a depth of 5cm in mineral soil) at 1% level. The calculated Q1o values in this study,ranging from 2.03 to 2.36, were very near to those of tropical soil reported. The CO2 efflux in 2003was 5.34 kgCO2· m-2. a-1 from soil plus litter plus seedling, of them 3.48 kgCO2· m-2. a-1 from soil (accounting for 62.5%), 1.19 kgCO2· m-2. a-1 from litter (22.3%) and 0.67 kgCO2·m-2. a-1 from seedling (12.5%).

  19. Antibacterial, Antibiofilm Effect of Burdock (Arctium lappa L.) Leaf Fraction and Its Efficiency in Meat Preservation.

    Science.gov (United States)

    Lou, Zaixiang; Li, Cheng; Kou, Xingran; Yu, Fuhao; Wang, Hongxin; Smith, Gary M; Zhu, Song

    2016-08-01

    First, the antibacterial, antibiofilm effect and chemical composition of burdock (Arctium lappa L.) leaf fractions were studied. Then, the efficiency of burdock leaf fractions in pork preservation was evaluated. The results showed that burdock leaf fraction significantly inhibited the growth and biofilm development of Escherichia coli and Salmonella Typhimurium. MICs of burdock leaf fractions on E. coli and Salmonella Typhimurium were both 2 mg/ml. At a concentration of 2.0 mg/ml, the inhibition rates of the fraction on growth and development of E. coli and Salmonella Typhimurium biofilms were 78.7 and 69.9%, respectively. During storage, the log CFU per gram of meat samples treated with burdock leaf fractions decreased 2.15, compared with the samples without treatment. The shelf life of pork treated with burdock leaf fractions was extended 6 days compared with the pork without treatment, and the sensory property was obviously improved. Compared with the control group, burdock leaf fraction treatment significantly decreased the total volatile basic nitrogen value and pH of the meat samples. Chemical composition analysis showed that the burdock leaf fraction consisted of chlorogenic acid, caffeic acid, p-coumaric acid, rutin, cynarin, crocin, luteolin, arctiin, and quercetin. As a vegetable with an abundant source, burdock leaf is safe, affordable, and efficient in meat preservation, indicating that burdock leaf fraction is a promising natural preservative for pork.

  20. An application of plot-scale NDVI in predicting carbon dioxide exchange and leaf area index in heterogeneous subarctic tundra

    Energy Technology Data Exchange (ETDEWEB)

    Dagg, J.; Lafleur, P.

    2010-07-01

    This paper reported on a study that examined the flow of carbon into and out of tundra ecosystems. It is necessary to accurately predict carbon dioxide (CO{sub 2}) exchange in the Tundra because of the impacts of climate change on carbon stored in permafrost. Understanding the relationships between the normalized difference vegetation index (NDVI) and vegetation and CO{sub 2} exchange may explain how small-scale variation in vegetation community extends to remotely sensed estimates of landscape characteristics. In this study, CO{sub 2} fluxes were measured with a portable chamber in a range of Tundra vegetation communities. Biomass and leaf area were measured with destructive harvest, and NDVI was obtained using a hand-held infrared camera. There was a weak correlation between NDVI and leaf area index in some vegetation communities, but a significant correlation between NDVI and biomass, including mosses. NDVI was found to be strongly related to photosynthetic activity and net CO{sub 2} uptake in all vegetation groups. However, NDVI related to ecosystem respiration only in wet sedge. It was concluded that at plot scale, the ability of NDVI to predict ecosystem properties and CO{sub 2} exchange in heterogeneous Tundra vegetation is variable.