WorldWideScience

Sample records for residual stomatal transpiration

  1. Canopy Transpiration and Stomatal Responses to Prolonged Drought by a Dominant Desert Species in Central Asia

    Directory of Open Access Journals (Sweden)

    Daxing Gu

    2017-06-01

    Full Text Available In arid and semiarid lands, canopy transpiration and its dynamics depend largely on stomatal sensitivity to drought. In this study, the sap flow of a dominant species, Haloxylon ammodendron growing in Central Asian deserts, was monitored using Granier-type sensors, from which the canopy stomatal conductance was derived. The responses of canopy transpiration and stomatal conductance to environmental variables during the second half of the growing season, when annual prolonged drought occurred, was analyzed for four continuous years, from 2013 to 2016. A soil water content (SWC of 3% was identified as the lower soil water threshold for this species, below which the plant lost the ability for stomatal regulation on water loss and suffered the risk of mortality. Above this threshold, the sensitivity of canopy transpiration to vapor pressure deficit, VPD (K, was linearly correlated with SWC, which mainly resulted from different stomatal behaviors at varying drought intensities. Stomatal sensitivity to VPD (m/Gsref increased linearly with soil moisture deficit, inducing a shift from more anisohydric to a more isohydric stomatal behavior. The flexibility of stomatal behavior regarding soil drought was one key element facilitating the survival of H. ammodendron in such an extreme dry environment.

  2. Predicting photosynthesis and transpiration responses to ozone: decoupling modeled photosynthesis and stomatal conductance

    Directory of Open Access Journals (Sweden)

    D. Lombardozzi

    2012-08-01

    Full Text Available Plants exchange greenhouse gases carbon dioxide and water with the atmosphere through the processes of photosynthesis and transpiration, making them essential in climate regulation. Carbon dioxide and water exchange are typically coupled through the control of stomatal conductance, and the parameterization in many models often predict conductance based on photosynthesis values. Some environmental conditions, like exposure to high ozone (O3 concentrations, alter photosynthesis independent of stomatal conductance, so models that couple these processes cannot accurately predict both. The goals of this study were to test direct and indirect photosynthesis and stomatal conductance modifications based on O3 damage to tulip poplar (Liriodendron tulipifera in a coupled Farquhar/Ball-Berry model. The same modifications were then tested in the Community Land Model (CLM to determine the impacts on gross primary productivity (GPP and transpiration at a constant O3 concentration of 100 parts per billion (ppb. Modifying the Vcmax parameter and directly modifying stomatal conductance best predicts photosynthesis and stomatal conductance responses to chronic O3 over a range of environmental conditions. On a global scale, directly modifying conductance reduces the effect of O3 on both transpiration and GPP compared to indirectly modifying conductance, particularly in the tropics. The results of this study suggest that independently modifying stomatal conductance can improve the ability of models to predict hydrologic cycling, and therefore improve future climate predictions.

  3. Environmental controls on saltcedar (Tamarix spp.) transpiration and stomatal conductance and implications for determining evapotranspiration by remote sensing

    Science.gov (United States)

    Nagler, P. L.; Glenn, E. P.; morino, K.

    2012-12-01

    Saltcedar is an introduced, salt-tolerant shrub that now dominates many flow-regulated western U.S. rivers. Saltcedar control programs have been implemented to salvage water and to allow the return of native vegetation to infested rivers. However, there is much debate about how much water saltcedar actually uses and the range of ecohydrological niches it occupies. Ground methods for measuring riparian zone ET have improved and there is considerable interest in developing remote sensing methods for saltcedar to conduct wide-area monitoring of water use. Both thermal band and vegetation index methods have been used to estimate riparian ET. However, several problems present themselves in applying existing remote sensing methods to riparian corridors. First, many riparian corridors are narrow and are surrounded by arid uplands, hence they cannot be treated as energetically closed systems, an assumption of thermal band methods that calculate ET as a residual in the surface energy balance. Second, contrary to the assumption that riparian phreatophytes typically grow under unstressed conditions since they are rooted into groundwater, we find that saltcedar stands are under substantial degrees of apparent moisture stress, exhibiting midday depression of transpiration and stomatal conductance, and decreases in stomatal conductance over the growing season as depth to groundwater increases. Furthermore, the degree of stress is site-specific, depending on local soil texture, salinity of the groundwater and distance from the river. This violates a key assumption of vegetation index methods for estimating ET. The implications of these findings for arid-zone riparian ecohydrology and for remote sensing methods that assume either a constant daily evaporative fraction or rate of stomatal conductance will be discussed using saltcedar stands measured in the Cibola NWR on the lower Colorado River as a case study. Daily rates of saltcedar transpiration ranged from 1.6-3.0 mm/m2 leaf

  4. Modelling of root ABA synthesis, stomatal conductance, transpiration and potato production under water saving irrigation regimes

    DEFF Research Database (Denmark)

    Plauborg, Finn; Abrahamsen, Per; Gjettermann, Birgitte

    2010-01-01

    . Experimental data was compared to simulated results from the new enhanced Daisy model which include modelling 2D soil water flow, abscisic acid (ABA) signalling and its effect on stomatal conductance and hence on transpiration and assimilation, and finally crop yield. The results demonstrated that the enhanced......Application of water saving irrigation strategies in agriculture has become increasingly important. Both modelling and experimental work are needed to gain more insights into the biological and physical mechanisms in the soil-plant system, which regulates water flow in the system and plays...... a central role in reducing crop transpiration. This paper presented a mechanistic model (Daisy) developed based on data obtained in the SAFIR project on measured leaf gas exchange and soil water dynamics in irrigated potato crops grown in a semi-field environment subjected to different irrigation regimes...

  5. Carbonyl sulfide (COS) as a tracer for canopy photosynthesis, transpiration and stomatal conductance: potential and limitations.

    Science.gov (United States)

    Wohlfahrt, Georg; Brilli, Federico; Hörtnagl, Lukas; Xu, Xiaobin; Bingemer, Heinz; Hansel, Armin; Loreto, Francesco

    2012-04-01

    The theoretical basis for the link between the leaf exchange of carbonyl sulfide (COS), carbon dioxide (CO(2)) and water vapour (H(2)O) and the assumptions that need to be made in order to use COS as a tracer for canopy net photosynthesis, transpiration and stomatal conductance, are reviewed. The ratios of COS to CO(2) and H(2)O deposition velocities used to this end are shown to vary with the ratio of the internal to ambient CO(2) and H(2)O mole fractions and the relative limitations by boundary layer, stomatal and internal conductance for COS. It is suggested that these deposition velocity ratios exhibit considerable variability, a finding that challenges current parameterizations, which treat these as vegetation-specific constants. COS is shown to represent a better tracer for CO(2) than H(2)O. Using COS as a tracer for stomatal conductance is hampered by our present poor understanding of the leaf internal conductance to COS. Estimating canopy level CO(2) and H(2)O fluxes requires disentangling leaf COS exchange from other ecosystem sources/sinks of COS. We conclude that future priorities for COS research should be to improve the quantitative understanding of the variability in the ratios of COS to CO(2) and H(2)O deposition velocities and the controlling factors, and to develop operational methods for disentangling ecosystem COS exchange into contributions by leaves and other sources/sinks. To this end, integrated studies, which concurrently quantify the ecosystem-scale CO(2), H(2)O and COS exchange and the corresponding component fluxes, are urgently needed. © 2011 Blackwell Publishing Ltd.

  6. Transpiration and stomatal resistance variations of perennial tropical crops under soil water availability conditions and water deficit

    Directory of Open Access Journals (Sweden)

    José Ozinaldo Alves de Sena

    2007-03-01

    Full Text Available During the dry and rainy seasons, determinations of stomatal resistance and transpiration of five tropical crops were carried out: guarana (Paullinia cupana Kunth, coffee (Coffea arabica L., cashew (Anacardium occidentale L., guava (Psidium guajava L. and rubber (Hevea brasiliensis Muell. - Arg. trees. Experimental design was done at randomized complete blocks with five replications. During the dry season there was a decrease in values of stomatal resistance in the following order: guarana > coffee> cashew> guava > rubber, with values from 2.5 to 30.0 s.cm-1. During the rainy season the stomatal resistance values varied from 1.5 to 3.0 s.cm-1. The guarana and coffee crops showed higher resistance to water transpiration when compared to other crops. During the rainy season, the rubber tree continued to present lower stomatal resistance and, consequently, higher transpiration.O experimento foi realizado no Departamento de Produção Vegetal da Escola Superior de Agricultura "Luiz de Queiroz", ESALQ/USP, Piracicaba, São Paulo, Brasil, utilizando-se as culturas de guaranazeiro (Paullinia cupana Kunth, cafeeiro (Coffea arabica L., cajueiro (Anacardium occidentale L., goiabeira (Psidium guajava L. e seringueira (Hevea brasiliensis Muell. - Arg.. No período de seca (setembro/94 e de chuvas (novembro/94, realizaram-se determinações de resistência estomática (RE (s cm-1 e transpiração (T (µg cm-1 s-1 nas diferentes espécies. O delineamento experimental foi em blocos casualizados com cinco repetições. A partir das análises dos dados pode-se concluir: 1. diferenças significativas entre espécies, em termos das variáveis avaliadas no período de deficiência hídrica, com valores decrescentes de resistência estomática e crescente de transpiração na seguinte ordem: guaranazeiro > cafeeiro > cajueiro > goiabeira > seringueira; 2. Nas águas as diferenças entre espécies, para ambas as variáveis, foram menos evidentes, continuando a

  7. Stomatal acclimation to vapour pressure deficit doubles transpiration of small tree seedlings with warming

    DEFF Research Database (Denmark)

    Marchin, Renée M.; Broadhead, Alice A.; Bostic, Laura E.

    2016-01-01

    Future climate change is expected to increase temperature (T) and atmospheric vapour pressure deficit (VPD) in many regions, but the effect of persistent warming on plant stomatal behaviour is highly uncertain. We investigated the effect of experimental warming of 1.9-5.1 °C and increased VPD of 0...... chamber VPD. Warming increased mean water use of Carya by 140% and Quercus by 150%, but had no significant effect on water use of Acer. Increased water use of ring-porous species was attributed to (1) higher air T and (2) stomatal acclimation to VPD resulting in higher gs and more sensitive stomata...

  8. Wheat cultivars selected for high Fv/Fm under heat stress maintain high photosynthesis, total chlorophyll, stomatal conductance, transpiration and dry matter

    DEFF Research Database (Denmark)

    Sharma, Dew Kumari; Andersen, Sven Bode; Ottosen, Carl Otto

    2015-01-01

    ) than the low group, accompanied by higher stomatal conductance (gs), transpiration rate (E) and evaporative cooling of the leaf (ΔT). The difference in PN between the groups was not caused by differences in PSII capacity or gs as the variation in Fv/Fm and intracellular CO2 (Ci) was non...... variation for tolerance to severe heat stress (3 days at 40∘C in controlled conditions) in wheat (Triticum aestivum L.). Here we investigated the performance of the previously selected cultivars (high and low group based on Fv/Fm value) in terms of growth and photosynthetic traits undermoderate heat stress...

  9. Cultivar Differences in Plant Transpiration Rate at High Relative Air Humidity Are Not Related to Genotypic Variation in Stomatal Responsiveness

    DEFF Research Database (Denmark)

    Gebraegziabher, Habtamu Giday; Kjær, Katrine Heinsvig; Ottosen, Carl-Otto

    2015-01-01

    Plants grown at high relative air humidity (RH) often show disturbed water relations due to less responsive stomata. The attenuation of stomatal responsiveness as a result of high RH during leaf expansion depends on the cultivar. We hypothesized that tolerant cultivars to high RH experience a lower...

  10. Effect of (Changes in) Air Humidity on Transpiration and (Adaptation of) Stomatal Closure of Tradescantia Leaves during Water Stress

    NARCIS (Netherlands)

    Meeteren, van U.; Rezaei Nejad, A.; Harbinson, J.

    2009-01-01

    This paper summarises our recent research on the physiological effects of prolonged high RH during growth on stomatal function and we discuss possibilities that arise from this work for reducing postharvest quality problems in cut flowers. Chlorophyll fluorescence imaging was used to measure

  11. Effects of Bois noir on carbon assimilation, transpiration, stomatal conductance of leaves and yield of grapevine (Vitis vinifera) cv. Chardonnay.

    Science.gov (United States)

    Endeshaw, Solomon T; Murolo, Sergio; Romanazz, Gianfranco; Neri, Davide

    2012-06-01

    Bois noir (BN) is one of the main phytoplasma diseases of grapevine (Vitis vinifera). It is widespread, and can cause severe losses in European vineyards. The infective agent colonizes phloem elements and induces visible symptoms of leaf yellowing or reddening after a relatively long incubation period. As the most sensitive cultivars to BN, Chardonnay plants were grouped as healthy or symptomatic in spring, based on the records from the previous year. Leaf gas exchange and chlorophyll a fluorescence were measured weekly from July to September in healthy plants, and in symptomatic and asymptomatic leaves from symptomatic plants. The midday relative water content (mRWC) was measured once per month. The detection of phytoplasma DNA by nested-polymerase chain reaction revealed BN infection in symptomatic leaf samples at the end of September. A significant decrease in pigment content and maximum quantum efficiency of photosystem II (Fv/Fm) of these symptomatic leaves was detected from July to September, although in the asymptomatic leaves of the symptomatic plants the net photosynthesis (Pn) decrease was not significant. In the leaves from the healthy plants, Pn and transpiration were relatively stable. Of note, in July, an initially healthy plant showed a strong Pn reduction that was followed by visible leaf yellowing symptoms only in August. The phytoplasma infection also stimulated significant reductions in mRWC of the symptomatic leaves, with a final large decrease in yield.

  12. Measuring and Modeling Tree Stand Level Transpiration

    Science.gov (United States)

    J.M. Vose; G.J. Harvey; K.J. Elliott; B.D. Clinton

    2003-01-01

    Transpiration is a key process in the application of phytoremediation to soil or groundwater pollutants. To be successful, vegetation must transpire enough water from the soil or groundwater to control or take up the contaminant. Transpiration is driven by a combination of abiotic (climate, soil water availability, and groundwater depth) and biotic (leaf area, stomatal...

  13. Fotossíntese, condutância estomática e transpiração em pupunheira sob deficiência hídrica Photosynthesis, stomatal conductance and transpiration in peach palm under water stress

    Directory of Open Access Journals (Sweden)

    Maria Aparecida José de Oliveira

    2002-03-01

    Full Text Available Resultados de pesquisa envolvendo aspectos fisiológicos da pupunheira (Bactris gasipaes Kunth, fruteira nativa da América Tropical, são escassos. Procurando completar essa lacuna, um experimento sob deficiência hídrica foi conduzido em casa de vegetação, durante um período de 13 dias, utilizando plantas de 12 meses de idade. O objetivo principal foi avaliar as respostas da pupunheira à deficiência hídrica. As variáveis observadas foram: taxa de assimilação de CO2, transpiração, condutância estomática e potencial de água das folhas. As coletas dos dados foram realizadas diariamente em laboratório e sob fluxo de 1200 mim-2 s-1. Os resultados foram submetidos à análise de variância e de regressão. Verificou-se decréscimo no potencial de água da folha e nas trocas gasosas quando a irrigação foi interrompida por mais de seis dias. Valores mínimos foram obtidos no décimo dia, com redução de 92% da fotossíntese líquida, 87% da condutância estomática e 70% da transpiração. O menor potencial de água nas folhas (-1,9 MPa foi também observado nesse período. Houve recuperação total de todas as variáveis dois dias após reirrigação, com exceção da condutância estomática. A diminuição da condutância estomática e a queda mais rápida da taxa de transpiração que a queda na fotossíntese, indicam a existência de mecanismos de aclimatação em pupunheira, no sentido de diminuir as perdas de água, quando sob condição de estresse hídrico moderado.Research results on physiological aspects of peach palm (Bactris gasipaes Kunth, a native fruit tree from tropical America, are scarce. Trying to fill this gap, a water deficit experiment was performed under nursery conditions during 13 days, utilizing 12 months old plants. The main objective was to evaluate peach palm responses to water deficit. The measured variables were: CO2 assimilation rate, transpiration rate, stomatal conductance and leaf water potential

  14. Transpiration: A Test of Optimality Hypothesis

    Science.gov (United States)

    Wang, J.; Bras, R. L.; Lerdau, M.; Salvucci, G. D.; Wofsy, S.

    2003-12-01

    The argument is that the fundamental mechanisms behind bare soil evaporation are also responsible for plant transpiration except that stomata affect the exchange of water vapor between the evaporating surface and the atmosphere. It is hypothesized that the system of liquid water in leaf tissues and the water vapor in the atmosphere tries to evolve towards a potential equilibrium as quickly as possible by maximizing transpiration. In the proposed theory, CO2 flux is used as a non-parametric equivalent of stomatal conductance as CO2 and water vapor diffuse in and out of leaves through the same path. It is further assumed that stomatal aperture is directly controlled by guard cell turgor (or leaf water potential). Transpiration is formulated as a function of leaf temperature, leaf water potential/stomatal conductance (or CO2 flux as the surrogate), and sensible heat flux (characterizing transport mechanism) at a given level of radiative energy input. Optimization of transpiration constrained by the energy balance equation leads to vanishing derivatives of transpiration with respect to leaf temperature and CO2 flux. Effect of vapor pressure deficit on transpiration is also investigated. Preliminary tests using field experimental measurements lead to encouraging evidence in support of the hypothesis. It is found that transpiration is fairly insensitive to atmospheric humidity as suggested by several earlier studies.

  15. Role of Sucrose in Emerging Mechanisms of Stomatal Aperture Regulation.

    Energy Technology Data Exchange (ETDEWEB)

    Outlaw, W. H.

    2000-09-15

    Focused on the second of 2 hypotheses that were proposed for testing that transpiration rate determines the extent to which suc accumulates in the GC wall providing a mechanism for regulating stomatal aperture size.

  16. Sensitivity of stand transpiration to wind velocity in a mixed broadleaved deciduous forest

    Science.gov (United States)

    Dohyoung Kim; Ram Oren; A. Christopher Oishi; Cheng-I Hsieh; Nathan Phillips; Kimberly A. Novick; Paul C. Stoy

    2014-01-01

    Wind velocity (U) within and above forest canopies can alter the coupling between the vapor-saturated sub-stomatal airspace and the drier atmosphere aloft, thereby influencing transpiration rates. In practice, however, the actual increase in transpiration with increasing U depends on the aerodynamic resistance (RA) to vapor transfer compared to canopy resistance to...

  17. Transpiration and crop yields

    NARCIS (Netherlands)

    Wit, de C.T.

    1958-01-01

    Theoretical and practical aspects of the transpiration of crops in the field are discussed and he concludes that the relationship between transpiration and total dry matter production is much less affected by growing conditions than has been supposed. In semi-arid and arid regions, this relationship

  18. K(+) starvation inhibits water-stress-induced stomatal closure.

    Science.gov (United States)

    Benlloch-González, María; Arquero, Octavio; Fournier, José María; Barranco, Diego; Benlloch, Manuel

    2008-04-18

    The effect of potassium starvation on stomatal conductance was studied in olive trees and sunflower plants, two major crops with greatly differing botanical characteristics. In both species, K(+) starvation inhibited water-stress-induced stomatal closure. In olive trees, potassium starvation favoured stomatal conductance and transpiration, as well as inhibiting shoot growth, in the three cultivars studied: 'Lechín de Granada', 'Arbequina' and 'Chetoui'. However, 'Lechín de Granada' - generally considered more drought-tolerant than 'Arbequina' and 'Chetoui' - proved less susceptible to potassium starvation. Results for olive trees also suggest genetic variability in olive cultivars in relation to potassium requirements for stem growth and the regulation of water transpiration. The results obtained suggest that inhibition of the stomatal closure mechanism produced by moderate potassium starvation is a widespread plant physiological disorder, and may be the cause of tissue dehydration in many water-stressed crops.

  19. The ERECTA gene regulates plant transpiration efficiency in Arabidopsis.

    Science.gov (United States)

    Masle, Josette; Gilmore, Scott R; Farquhar, Graham D

    2005-08-11

    Assimilation of carbon by plants incurs water costs. In the many parts of the world where water is in short supply, plant transpiration efficiency, the ratio of carbon fixation to water loss, is critical to plant survival, crop yield and vegetation dynamics. When challenged by variations in their environment, plants often seem to coordinate photosynthesis and transpiration, but significant genetic variation in transpiration efficiency has been identified both between and within species. This has allowed plant breeders to develop effective selection programmes for the improved transpiration efficiency of crops, after it was demonstrated that carbon isotopic discrimination, Delta, of plant matter was a reliable and sensitive marker negatively related to variation in transpiration efficiency. However, little is known of the genetic controls of transpiration efficiency. Here we report the isolation of a gene that regulates transpiration efficiency, ERECTA. We show that ERECTA, a putative leucine-rich repeat receptor-like kinase (LRR-RLK) known for its effects on inflorescence development, is a major contributor to a locus for Delta on Arabidopsis chromosome 2. Mechanisms include, but are not limited to, effects on stomatal density, epidermal cell expansion, mesophyll cell proliferation and cell-cell contact.

  20. Nutrient and water addition effects on day- and night-time conductance and transpiration in a C3 desert annual

    NARCIS (Netherlands)

    Ludwig, F.; Jewitt, R.A.; Donovan, L.A.

    2006-01-01

    Recent research has shown that many C3 plant species have significant stomatal opening and transpire water at night even in desert habitats. Day-time stomatal regulation is expected to maximize carbon gain and prevent runaway cavitation, but little is known about the effect of soil resource

  1. Relating Stomatal Conductance to Leaf Functional Traits.

    Science.gov (United States)

    Kröber, Wenzel; Plath, Isa; Heklau, Heike; Bruelheide, Helge

    2015-10-12

    Leaf functional traits are important because they reflect physiological functions, such as transpiration and carbon assimilation. In particular, morphological leaf traits have the potential to summarize plants strategies in terms of water use efficiency, growth pattern and nutrient use. The leaf economics spectrum (LES) is a recognized framework in functional plant ecology and reflects a gradient of increasing specific leaf area (SLA), leaf nitrogen, phosphorus and cation content, and decreasing leaf dry matter content (LDMC) and carbon nitrogen ratio (CN). The LES describes different strategies ranging from that of short-lived leaves with high photosynthetic capacity per leaf mass to long-lived leaves with low mass-based carbon assimilation rates. However, traits that are not included in the LES might provide additional information on the species' physiology, such as those related to stomatal control. Protocols are presented for a wide range of leaf functional traits, including traits of the LES, but also traits that are independent of the LES. In particular, a new method is introduced that relates the plants' regulatory behavior in stomatal conductance to vapor pressure deficit. The resulting parameters of stomatal regulation can then be compared to the LES and other plant functional traits. The results show that functional leaf traits of the LES were also valid predictors for the parameters of stomatal regulation. For example, leaf carbon concentration was positively related to the vapor pressure deficit (vpd) at the point of inflection and the maximum of the conductance-vpd curve. However, traits that are not included in the LES added information in explaining parameters of stomatal control: the vpd at the point of inflection of the conductance-vpd curve was lower for species with higher stomatal density and higher stomatal index. Overall, stomata and vein traits were more powerful predictors for explaining stomatal regulation than traits used in the LES.

  2. Quantitative trait loci mapping for stomatal traits in interspecific ...

    Indian Academy of Sciences (India)

    M. Sumathi

    2018-02-23

    Feb 23, 2018 ... to be correlated with the rate of photosynthesis and transpiration .... sured in micrometre (μm) from abaxial and adaxial leaf surfaces. Stomatal area (μm2) was calculated using the following formula (Wang et al. 2012),. SL × SW × π. 4 .... **P < 0.01; *P < 0.05; ns, not significant; SE, standard error. Table 3.

  3. Linking stomatal sensitivity and whole-tree hydraulic architecture

    Science.gov (United States)

    Katherine A. McCulloh; David R. Woodruff

    2012-01-01

    Despite the complexity of the relationship between stomatal sensitivity, water loss and vulnerability to embolism, the goal of teasing apart the subtleties is a necessary one. As Litvak et al. (2012) mention, determining transpiration patterns based on vulnerability to embolism would be much easier than the lengthy and potentially expensive processes involved in sap...

  4. Bayesian analysis for uncertainty estimation of a canopy transpiration model

    Science.gov (United States)

    Samanta, S.; Mackay, D. S.; Clayton, M. K.; Kruger, E. L.; Ewers, B. E.

    2007-04-01

    A Bayesian approach was used to fit a conceptual transpiration model to half-hourly transpiration rates for a sugar maple (Acer saccharum) stand collected over a 5-month period and probabilistically estimate its parameter and prediction uncertainties. The model used the Penman-Monteith equation with the Jarvis model for canopy conductance. This deterministic model was extended by adding a normally distributed error term. This extension enabled using Markov chain Monte Carlo simulations to sample the posterior parameter distributions. The residuals revealed approximate conformance to the assumption of normally distributed errors. However, minor systematic structures in the residuals at fine timescales suggested model changes that would potentially improve the modeling of transpiration. Results also indicated considerable uncertainties in the parameter and transpiration estimates. This simple methodology of uncertainty analysis would facilitate the deductive step during the development cycle of deterministic conceptual models by accounting for these uncertainties while drawing inferences from data.

  5. Fruit load governs transpiration of olive trees.

    Science.gov (United States)

    Bustan, Amnon; Dag, Arnon; Yermiyahu, Uri; Erel, Ran; Presnov, Eugene; Agam, Nurit; Kool, Dilia; Iwema, Joost; Zipori, Isaac; Ben-Gal, Alon

    2016-03-01

    We tested the hypothesis that whole-tree water consumption of olives (Olea europaea L.) is fruit load-dependent and investigated the driving physiological mechanisms. Fruit load was manipulated in mature olives grown in weighing-drainage lysimeters. Fruit was thinned or entirely removed from trees at three separate stages of growth: early, mid and late in the season. Tree-scale transpiration, calculated from lysimeter water balance, was found to be a function of fruit load, canopy size and weather conditions. Fruit removal caused an immediate decline in water consumption, measured as whole-plant transpiration normalized to tree size, which persisted until the end of the season. The later the execution of fruit removal, the greater was the response. The amount of water transpired by a fruit-loaded tree was found to be roughly 30% greater than that of an equivalent low- or nonyielding tree. The tree-scale response to fruit was reflected in stem water potential but was not mirrored in leaf-scale physiological measurements of stomatal conductance or photosynthesis. Trees with low or no fruit load had higher vegetative growth rates. However, no significant difference was observed in the overall aboveground dry biomass among groups, when fruit was included. This case, where carbon sources and sinks were both not limiting, suggests that the role of fruit on water consumption involves signaling and alterations in hydraulic properties of vascular tissues and tree organs. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  6. The effect of blue light on stomatal oscillations and leaf turgor pressure in banana leaves.

    Science.gov (United States)

    Zait, Yotam; Shapira, Or; Schwartz, Amnon

    2017-07-01

    Stomatal oscillations are cyclic opening and closing of stomata, presumed to initiate from hydraulic mismatch between leaf water supply and transpiration rate. To test this assumption, mismatches between water supply and transpiration were induced using manipulations of vapour pressure deficit (VPD) and light spectrum in banana (Musa acuminata). Simultaneous measurements of gas exchange with changes in leaf turgor pressure were used to describe the hydraulic mismatches. An increase of VPD above a certain threshold caused stomatal oscillations with variable amplitudes. Oscillations in leaf turgor pressure were synchronized with stomatal oscillations and balanced only when transpiration equaled water supply. Surprisingly, changing the light spectrum from red and blue to red alone at constant VPD also induced stomatal oscillations - while the addition of blue (10%) to red light only ended oscillations. Blue light is known to induce stomatal opening and thus should increase the hydraulic mismatch, reduce the VPD threshold for oscillations and increase the oscillation amplitude. Unexpectedly, blue light reduced oscillation amplitude, increased VPD threshold and reduced turgor pressure loss. These results suggest that additionally, to the known effect of blue light on the hydroactive opening response of stomata, it can also effect stomatal movement by increased xylem-epidermis water supply. © 2017 John Wiley & Sons Ltd.

  7. A rate equation model of stomatal responses to vapour pressure deficit and drought

    Directory of Open Access Journals (Sweden)

    Shanahan ST

    2002-08-01

    Full Text Available Abstract Background Stomata respond to vapour pressure deficit (D – when D increases, stomata begin to close. Closure is the result of a decline in guard cell turgor, but the link between D and turgor is poorly understood. We describe a model for stomatal responses to increasing D based upon cellular water relations. The model also incorporates impacts of increasing levels of water stress upon stomatal responses to increasing D. Results The model successfully mimics the three phases of stomatal responses to D and also reproduces the impact of increasing plant water deficit upon stomatal responses to increasing D. As water stress developed, stomata regulated transpiration at ever decreasing values of D. Thus, stomatal sensitivity to D increased with increasing water stress. Predictions from the model concerning the impact of changes in cuticular transpiration upon stomatal responses to increasing D are shown to conform to experimental data. Sensitivity analyses of stomatal responses to various parameters of the model show that leaf thickness, the fraction of leaf volume that is air-space, and the fraction of mesophyll cell wall in contact with air have little impact upon behaviour of the model. In contrast, changes in cuticular conductance and membrane hydraulic conductivity have significant impacts upon model behaviour. Conclusion Cuticular transpiration is an important feature of stomatal responses to D and is the cause of the 3 phase response to D. Feed-forward behaviour of stomata does not explain stomatal responses to D as feedback, involving water loss from guard cells, can explain these responses.

  8. The importance of micrometeorological variations for photosynthesis and transpiration in a boreal coniferous forest

    DEFF Research Database (Denmark)

    Schurgers, Guy; Lagergren, F.; Molder, M.

    2015-01-01

    the importance of vertical variations in light, temperature, CO2 concentration and humidity within the canopy for fluxes of photosynthesis and transpiration of a boreal coniferous forest in central Sweden. A leaf-level photosynthesis-stomatal conductance model was used for aggregating these processes to canopy...... abovecanopy and within-canopy humidity, and despite large gradients in CO2 concentration during early morning hours after nights with stable conditions, neither humidity nor CO2 played an important role for vertical heterogeneity of photosynthesis and transpiration....

  9. Balancing Water Uptake and Loss through the Coordinated Regulation of Stomatal and Root Development

    Science.gov (United States)

    Hepworth, Christopher; Turner, Carla; Landim, Marcela Guimaraes; Cameron, Duncan; Gray, Julie E.

    2016-01-01

    Root development is influenced by nutrient and water availabilities. Plants are able to adjust many attributes of their root in response to environmental signals including the size and shape of the primary root, lateral roots and root hairs. Here we investigated the response of roots to changes in the levels of leaf transpiration associated with altered stomatal frequency. We found that plants with high stomatal density and conductance produce a larger rooting area and as a result have enhanced phosphate uptake capacity whereas plants with low stomatal conductance produce a smaller root. Manipulating the growth environment of plants indicated that enhanced root growth is most likely a result of an increased demand for water rather than phosphate. Plants manipulated to have an increase or reduction in root hair growth show a reduction or increase respectively, in stomatal conductance and density. Our results demonstrate that plants can balance their water uptake and loss through coordinated regulation of both stomatal and root development. PMID:27275842

  10. Influence of stomatic aperture on photosynthetic activity of bean-seedlings leaves

    International Nuclear Information System (INIS)

    Suarez Moya, J.; Fernandez Gonzalez, J.

    1984-01-01

    The present paper contains the data of photosynthetic activity and stomatic aperture of bean-seedlings Ieaves, and the relations obtained with both results. It has been observed that the product of photosynthetic activity by the resistance; to transpiration measured by a promoter ia a constant, between some limits. (Author) 45 refs

  11. Stomatal response of an anisohydric grapevine cultivar to evaporative demand, available soil moisture and abscisic acid.

    Science.gov (United States)

    Rogiers, Suzy Y; Greer, Dennis H; Hatfield, Jo M; Hutton, Ron J; Clarke, Simon J; Hutchinson, Paul A; Somers, Anthony

    2012-03-01

    Stomatal responsiveness to evaporative demand (air vapour pressure deficit (VPD)) ranges widely between species and cultivars, and mechanisms for stomatal control in response to VPD remain obscure. The interaction of irrigation and soil moisture with VPD on stomatal conductance is particularly difficult to predict, but nevertheless is critical to instantaneous transpiration and vulnerability to desiccation. Stomatal sensitivity to VPD and soil moisture was investigated in Semillon, an anisohydric Vitis vinifera L. variety whose leaf water potential (Ψ(l)) is frequently lower than that of other grapevine varieties grown under similar conditions in the warm grape-growing regions of Australia. A survey of Semillon vines across seven vineyards revealed that, regardless of irrigation treatment, midday Ψ(l) was dependent on not only soil moisture but VPD at the time of measurement. Predawn Ψ(l) was more closely correlated to not only soil moisture in dry vineyards but to night-time VPD in drip-irrigated vineyards, with incomplete rehydration during high night-time VPD. Daytime stomatal conductance was low only under severe plant water deficits, induced by extremes in dry soil. Stomatal response to VPD was inconsistent across irrigation regime; however, in an unirrigated vineyard, stomatal sensitivity to VPD-the magnitude of stomatal response to VPD-was heightened under dry soils. It was also found that stomatal sensitivity was proportional to the magnitude of stomatal conductance at a reference VPD of 1kPa. Exogenous abscisic acid (ABA) applied to roots of Semillon vines growing in a hydroponic system induced stomatal closure and, in field vines, petiole xylem sap ABA concentrations rose throughout the morning and were higher in vines with low Ψ(l). These data indicate that despite high stomatal conductance of this anisohydric variety when grown in medium to high soil moisture, increased concentrations of ABA as a result of very limited soil moisture may augment

  12. Radon transport from uranium mill tailings via plant transpiration. Final report

    International Nuclear Information System (INIS)

    Lewis, B.A.G.

    1985-01-01

    Radon exhalation by vegetation planted on bare or soil-covered uranium mill wastes was studied based on an assumption that radon transport from soil to atmosphere via plants takes place in the transpiration stream. Results show that radon exhalation by plants is inversely related to water transpired, primarily a dilution effect. Radon released appeared directly related to leaf area, suggesting that radon is carried into the plant by mass flow in water; however, once within the plant, radon very likely diffuses through the entire leaf cuticle, while water vapor diffuses primarily through open stomates. Application of a computerized model for water transpiration to radon exhalation is not immediately useful until the role of water in radon transport is defined throughout the continuum from rooting medium to the atmosphere. Until then, a simple calculation based on leaf area index and Ra-226 concentration in the rooting medium can provide an estimate of radon release from revegetated wastes containing radium

  13. Buckwheat stomatal traits under aluminium toxicity

    Directory of Open Access Journals (Sweden)

    Oleksandr E. Smirnov

    2014-04-01

    Full Text Available Aluminium influence on some stomatal parameters of common buckwheat (Fagopyrum esculentum Moench. was studied. Significant changes in stomatal density, stomatal index and stomatal shape coefficient under aluminium treatment were revealed. Stomatal closure and no difference in total stomatal potential conductance index of treatment plants were suggested as aluminium resistance characteristics.

  14. Specialized stomatal humidity responses underpin ecological diversity in C3 bromeliads.

    Science.gov (United States)

    Males, Jamie; Griffiths, Howard

    2017-12-01

    The Neotropical Bromeliaceae display an extraordinary level of ecological variety, with species differing widely in habit, photosynthetic pathway and growth form. Divergences in stomatal structure and function, hitherto understudied in treatments of bromeliad evolutionary physiology, could have been critical to the generation of variety in ecophysiological strategies among the bromeliads. Because humidity is a key factor in bromeliad niches, we focussed on stomatal responses to vapour pressure deficit (VPD). We measured the sensitivity of stomatal conductance and assimilation rate to VPD in eight C 3 bromeliad species of contrasting growth forms and ecophysiological strategies and parameterised the kinetics of stomatal responses to a step change in VPD. Notably, three tank-epiphyte species displayed low conductance, high sensitivity and fast kinetics relative to the lithophytes, while three xeromorphic terrestrial species showed high conductance and sensitivity but slow stomatal kinetics. An apparent feedforward response of transpiration to VPD occurred in the tank epiphytes, while water-use efficiency was differentially impacted by stomatal closure depending on photosynthetic responses. Differences in stomatal responses to VPD between species of different ecophysiological strategies are closely linked to modifications of stomatal morphology, which we argue has been a pivotal component of the evolution of high diversity in this important plant family. © 2017 The Authors Plant, Cell & Environment Published by John Wiley & Sons Ltd.

  15. Impact of Leaf Traits on Temporal Dynamics of Transpired Oxygen Isotope Signatures and Its Impact on Atmospheric Vapor

    Science.gov (United States)

    Dubbert, Maren; Kübert, Angelika; Werner, Christiane

    2017-01-01

    Oxygen isotope signatures of transpiration (δE) are powerful tracers of water movement from plant to global scale. However, a mechanistic understanding of how leaf morphological/physiological traits effect δE is missing. A laser spectrometer was coupled to a leaf-level gas-exchange system to measure fluxes and isotopic signatures of plant transpiration under controlled conditions in seven distinct species (Fagus sylvatica, Pinus sylvestris, Acacia longifolia, Quercus suber, Coffea arabica, Plantago lanceolata, Oxalis triangularis). We analyzed the role of stomatal conductance (gs) and leaf water content (W) on the temporal dynamics of δE following changes in relative humidity (rH). Changes in rH were applied from 60 to 30% and from 30 to 60%, which is probably more than covering the maximum step changes occurring under natural conditions. Further, the impact of gs and W on isotopic non-steady state isofluxes was analyzed. Following changes in rH, temporal development of δE was well described by a one-pool modeling approach for most species. Isofluxes of δE were dominantly driven by stomatal control on E, particularly for the initial period of 30 min following a step change. Hence, the deviation of isofluxes from isotopic steady state can be large, even though plants transpire near to isotopic steady state. Notably, not only transpiration rate and stomatal conductance, but also the leaf traits stomatal density (as a measure of gmax) and leaf water content are significantly related to the time constant (τ) and non-steady-state isofluxes. This might provide an easy-to-access means of a priori assumptions for the impact of isotopic non-steady-state transpiration in various ecosystems. We discuss the implications of our results from leaf to ecosystem scale. PMID:28149303

  16. Plant transpiration at high elevations: Theory, field measurements, and comparisons with desert plants.

    Science.gov (United States)

    Smith, W K; Geller, G N

    1979-07-01

    The influence of elevational changes on plant transpiration was evaluated using leaf energy balance equations and well-known elevational changes in the physical parameters that influence water vapor diffusion. Simulated transpirational fluxes for large leaves with low and high stomatal resistances to water vapor diffusion were compared to small leaves with identical stomatal resistances at elevations ranging from sea level to 4 km. The specific influence of various air temperature lapse rates was also tested. Validation of the simulated results was accomplished by comparing actual field measurements taken at a low elevation (300 m) desert site with similar measurements for a high elevation (2,560 m) mountain research site. Close agreement was observed between predicted and measured values of transpiration for the environmental and leaf parameters tested.Substantial increases in solar irradiation and the diffusion coefficient for water vapor in air (D wv ) occurred with increasing elevation, while air and leaf temperatures, the water vapor concentration difference between the leaf and air, longwave irradiation, and the thermal conductivity coefficient for heat in air decreased with increasing elevation. These changes resulted in temperatures for sunlit leaves that were further above air temperature at higher elevations, especially for large leaves. For large leaves with low stomatal resistances, transpirational fluxes for low-elevation desert plants were close to those predicted for high-elevation plants even though the sunlit leaf temperatures of these mountain plants were over 10°C cooler. Simulating conditions with a low air temperature lapse rate (0.003° C m -1 and 0.004° C m -1 ) resulted in predicted transpirational fluxes that were greater than those calculated for the desert site. Transpiration for smaller leaves decreased with elevation for all lapse rates tested (0.003° C m -1 to 0.010° C m -1 ). However, transpirational fluxes at higher elevations

  17. Transpirational demand affects aquaporin expression in poplar roots.

    Science.gov (United States)

    Laur, Joan; Hacke, Uwe G

    2013-05-01

    Isohydric plants tend to maintain a water potential homeostasis primarily by controlling water loss via stomatal conductance. However, there is accumulating evidence that plants can also modulate water uptake in a dynamic manner. The dynamics of water uptake are influenced by aquaporin-mediated changes in root hydraulics. Most studies in this area have been conducted on herbaceous plants, and less is known about responses of woody plants. Here a study was conducted to determine how roots of hybrid poplar plants (Populus trichocarpa×deltoides) respond to a step change in transpirational demand. The main objective was to measure the expression of selected aquaporin genes and to assess how transcriptional responses correspond to changes in root water flow (Q R) and other parameters of water relations. A subset of plants was grown in shade and was subsequently exposed to a 5-fold increase in light level. Another group of plants was grown at ~95% relative humidity (RH) and was then subjected to lower RH while the light level remained unchanged. Both plant groups experienced a transient drop in stem water potentials. At 28h after the increase in transpirational demand, water potentials recovered. This recovery was associated with changes in the expression of PIP1 and PIP2 subfamily genes and an increase in Q R. Stomata of plants growing at high RH were larger and showed incomplete closure after application of abscisic acid. Since stomatal conductance remained high and unchanged in these plants, it is suggested that the recovery in water potential in these plants was largely driven by the increase in Q R.

  18. FPGA-based Fused Smart Sensor for Real-Time Plant-Transpiration Dynamic Estimation

    Directory of Open Access Journals (Sweden)

    Irineo Torres-Pacheco

    2010-09-01

    Full Text Available Plant transpiration is considered one of the most important physiological functions because it constitutes the plants evolving adaptation to exchange moisture with a dry atmosphere which can dehydrate or eventually kill the plant. Due to the importance of transpiration, accurate measurement methods are required; therefore, a smart sensor that fuses five primary sensors is proposed which can measure air temperature, leaf temperature, air relative humidity, plant out relative humidity and ambient light. A field programmable gate array based unit is used to perform signal processing algorithms as average decimation and infinite impulse response filters to the primary sensor readings in order to reduce the signal noise and improve its quality. Once the primary sensor readings are filtered, transpiration dynamics such as: transpiration, stomatal conductance, leaf-air-temperature-difference and vapor pressure deficit are calculated in real time by the smart sensor. This permits the user to observe different primary and calculated measurements at the same time and the relationship between these which is very useful in precision agriculture in the detection of abnormal conditions. Finally, transpiration related stress conditions can be detected in real time because of the use of online processing and embedded communications capabilities.

  19. Optimal Stomatal Behaviour Around the World: Synthesis of a Global Stomatal Conductance Database and Scaling from Leaf to Ecosystem

    Science.gov (United States)

    Lin, Y. S.; Medlyn, B. E.; Duursma, R.; Prentice, I. C.; Wang, H.

    2014-12-01

    Stomatal conductance (gs) is a key land surface attribute as it links transpiration, the dominant component of global land evapotranspiration and a key element of the global water cycle, and photosynthesis, the driving force of the global carbon cycle. Despite the pivotal role of gs in predictions of global water and carbon cycles, a global scale database and an associated globally applicable model of gs that allow predictions of stomatal behaviour are lacking. We present a unique database of globally distributed gs obtained in the field for a wide range of plant functional types (PFTs) and biomes. We employed a model of optimal stomatal conductance to assess differences in stomatal behaviour, and estimated the model slope coefficient, g1, which is directly related to the marginal carbon cost of water, for each dataset. We found that g1 varies considerably among PFTs, with evergreen savanna trees having the largest g1 (least conservative water use), followed by C3 grasses and crops, angiosperm trees, gymnosperm trees, and C4 grasses. Amongst angiosperm trees, species with higher wood density had a higher marginal carbon cost of water, as predicted by the theory underpinning the optimal stomatal model. There was an interactive effect between temperature and moisture availability on g1: for wet environments, g1 was largest in high temperature environments, indicated by high mean annual temperature during the period when temperature above 0oC (Tm), but it did not vary with Tm across dry environments. We examine whether these differences in leaf-scale behaviour are reflected in ecosystem-scale differences in water-use efficiency. These findings provide a robust theoretical framework for understanding and predicting the behaviour of stomatal conductance across biomes and across PFTs that can be applied to regional, continental and global-scale modelling of productivity and ecohydrological processes in a future changing climate.

  20. Processes driving nocturnal transpiration and implications for estimating land evapotranspiration.

    Science.gov (United States)

    de Dios, Víctor Resco; Roy, Jacques; Ferrio, Juan Pedro; Alday, Josu G; Landais, Damien; Milcu, Alexandru; Gessler, Arthur

    2015-06-15

    Evapotranspiration is a major component of the water cycle, yet only daytime transpiration is currently considered in Earth system and agricultural sciences. This contrasts with physiological studies where 25% or more of water losses have been reported to occur occurring overnight at leaf and plant scales. This gap probably arose from limitations in techniques to measure nocturnal water fluxes at ecosystem scales, a gap we bridge here by using lysimeters under controlled environmental conditions. The magnitude of the nocturnal water losses (12-23% of daytime water losses) in row-crop monocultures of bean (annual herb) and cotton (woody shrub) would be globally an order of magnitude higher than documented responses of global evapotranspiration to climate change (51-98 vs. 7-8 mm yr(-1)). Contrary to daytime responses and to conventional wisdom, nocturnal transpiration was not affected by previous radiation loads or carbon uptake, and showed a temporal pattern independent of vapour pressure deficit or temperature, because of endogenous controls on stomatal conductance via circadian regulation. Our results have important implications from large-scale ecosystem modelling to crop production: homeostatic water losses justify simple empirical predictive functions, and circadian controls show a fine-tune control that minimizes water loss while potentially increasing posterior carbon uptake.

  1. Gravimetric phenotyping of whole plant transpiration responses to atmospheric vapour pressure deficit identifies genotypic variation in water use efficiency.

    Science.gov (United States)

    Ryan, Annette C; Dodd, Ian C; Rothwell, Shane A; Jones, Ros; Tardieu, Francois; Draye, Xavier; Davies, William J

    2016-10-01

    There is increasing interest in rapidly identifying genotypes with improved water use efficiency, exemplified by the development of whole plant phenotyping platforms that automatically measure plant growth and water use. Transpirational responses to atmospheric vapour pressure deficit (VPD) and whole plant water use efficiency (WUE, defined as the accumulation of above ground biomass per unit of water used) were measured in 100 maize (Zea mays L.) genotypes. Using a glasshouse based phenotyping platform with naturally varying VPD (1.5-3.8kPa), a 2-fold variation in WUE was identified in well-watered plants. Regression analysis of transpiration versus VPD under these conditions, and subsequent whole plant gas exchange at imposed VPDs (0.8-3.4kPa) showed identical responses in specific genotypes. Genotype response of transpiration versus VPD fell into two categories: 1) a linear increase in transpiration rate with VPD with low (high WUE) or high (low WUE) transpiration rate at all VPDs, 2) a non-linear response with a pronounced change point at low VPD (high WUE) or high VPD (low WUE). In the latter group, high WUE genotypes required a significantly lower VPD before transpiration was restricted, and had a significantly lower rate of transpiration in response to VPD after this point, when compared to low WUE genotypes. Change point values were significantly positively correlated with stomatal sensitivity to VPD. A change point in stomatal response to VPD may explain why some genotypes show contradictory WUE rankings according to whether they are measured under glasshouse or field conditions. Furthermore, this novel use of a high throughput phenotyping platform successfully reproduced the gas exchange responses of individuals measured in whole plant chambers, accelerating the identification of plants with high WUE. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  2. Measuring Transpiration to Regulate Winter Irrigation Rates

    Energy Technology Data Exchange (ETDEWEB)

    Samuelson, Lisa [Auburn University

    2006-11-08

    Periodic transpiration (monthly sums) in a young loblolly pine plantation between ages 3 and 6 was measured using thermal dissipation probes. Fertilization and fertilization with irrigation were better than irrigation alone in increasing transpiration of young loblolly pines during winter months, apparently because of increased leaf area in fertilized trees. Irrigation alone did not significantly increase transpiration compared with the non-fertilized and non-irrigated control plots.

  3. Maize transpiration in response to meteorological conditions

    Science.gov (United States)

    Klimešová, Jana; Stŕedová, Hana; Stŕeda, Tomáš

    2013-09-01

    Differences in transpiration of maize (Zea mays L.) plants in four soil moisture regimes were quantified in a pot experiment. The transpiration was measured by the "Stem Heat Balance" method. The dependence of transpiration on air temperature, air humidity, global solar radiation, soil moisture, wind speed and leaf surface temperature were quantified. Significant relationships among transpiration, global radiation and air temperature (in the first vegetation period in the drought non-stressed variant, r = 0.881**, r = 0.934**) were found. Conclusive dependence of transpiration on leaf temperature (r = 0.820**) and wind speed (r = 0.710**) was found. Transpiration was significantly influenced by soil moisture (r = 0.395**, r = 0.528**) under moderate and severe drought stress. The dependence of transpiration on meteorological factors decreased with increasing deficiency of water. Correlation between transpiration and plant dry matter weight (r = 0.997**), plant height (r = 0.973**) and weight of corn cob (r = 0.987**) was found. The results of instrumental measuring of field crops transpiration under diverse moisture conditions at a concurrent monitoring of the meteorological elements spectra are rather unique. These results will be utilized in the effort to make calculations of the evapotranspiration in computing models more accurate.

  4. Stomatal guard cells co-opted an ancient ABA-dependent desiccation survival system to regulate stomatal closure.

    Science.gov (United States)

    Lind, Christof; Dreyer, Ingo; López-Sanjurjo, Enrique J; von Meyer, Katharina; Ishizaki, Kimitsune; Kohchi, Takayuki; Lang, Daniel; Zhao, Yang; Kreuzer, Ines; Al-Rasheid, Khaled A S; Ronne, Hans; Reski, Ralf; Zhu, Jian-Kang; Geiger, Dietmar; Hedrich, Rainer

    2015-03-30

    During the transition from water to land, plants had to cope with the loss of water through transpiration, the inevitable result of photosynthetic CO2 fixation on land [1, 2]. Control of transpiration became possible through the development of a new cell type: guard cells, which form stomata. In vascular plants, stomatal regulation is mediated by the stress hormone ABA, which triggers the opening of the SnR kinase OST1-activated anion channel SLAC1 [3, 4]. To understand the evolution of this regulatory circuit, we cloned both ABA-signaling elements, SLAC1 and OST1, from a charophyte alga, a liverwort, and a moss, and functionally analyzed the channel-kinase interactions. We were able to show that the emergence of stomata in the last common ancestor of mosses and vascular plants coincided with the origin of SLAC1-type channels capable of using the ancient ABA drought signaling kinase OST1 for regulation of stomatal closure. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Impact of Canopy Coupling on Canopy Average Stomatal Conductance Across Seven Tree Species in Northern Wisconsin

    Science.gov (United States)

    Ewers, B. E.; Mackay, D. S.; Samanta, S.; Ahl, D. E.; Burrows, S. S.; Gower, S. T.

    2001-12-01

    Land use changes over the last century in northern Wisconsin have resulted in a heterogeneous landscape composed of the following four main forest types: northern hardwoods, northern conifer, aspen/fir, and forested wetland. Based on sap flux measurements, aspen/fir has twice the canopy transpiration of northern hardwoods. In addition, daily transpiration was only explained by daily average vapor pressure deficit across the cover types. The objective of this study was to determine if canopy average stomatal conductance could be used to explain the species effects on tree transpiration. Our first hypothesis is that across all of the species, stomatal conductance will respond to vapor pressure deficit so as to maintain a minimum leaf water potential to prevent catostrophic cavitiation. The consequence of this hypothesis is that among species and individuals there is a proportionality between high stomatal conductance and the sensitivity of stomatal conductance to vapor pressure deficit. Our second hypothesis is that species that do not follow the proportionality deviate because the canopies are decoupled from the atmosphere. To test our two hypotheses we calculated canopy average stomatal conductance from sap flux measurements using an inversion of the Penman-Monteith equation. We estimated the canopy coupling using a leaf energy budget model that requires leaf transpiration and canopy aerodynamic conductance. We optimized the parameters of the aerodynamic conductance model using a Monte Carlo technique across six parameters. We determined the optimal model for each species by selecting parameter sets that resulted in the proportionality of our first hypothesis. We then tested the optimal energy budget models of each species by comparing leaf temperature and leaf width predicted by the models to measurements of each tree species. In red pine, sugar maple, and trembling aspen trees under high canopy coupling conditions, we found the hypothesized proportionality

  6. Modelling maximum canopy conductance and transpiration in ...

    African Journals Online (AJOL)

    There is much current interest in predicting the maximum amount of water that can be transpired by Eucalyptus trees. It is possible that industrial waste water may be applied as irrigation water to eucalypts and it is important to predict the maximum transpiration rates of these plantations in an attempt to dispose of this ...

  7. Measuring and modelling forest transpiration

    Czech Academy of Sciences Publication Activity Database

    Šír, Miloslav; Čermák, J.; Naděždina, N.; Pražák, Josef; Tesař, Miroslav

    2008-01-01

    Roč. 4, - (2008), č. 012050 ISSN 1755-1315. [Conference of the Danubian Countries on the Hydrological Forecasting and Hydrological Bases of Water Management /24./. Bled, 02.06.2008-04.06.2008] R&D Projects: GA ČR GA205/06/0375; GA ČR GA205/08/1174; GA ČR GA526/08/1016; GA MŠk MEB0808114; GA MŽP(CZ) SP/1A6/151/07; GA AV ČR 1QS200420562 Institutional research plan: CEZ:AV0Z20600510; CEZ:AV0Z20760514 Keywords : plant transpiration * SAP flow * floodplain forest Subject RIV: DA - Hydrology ; Limnology

  8. Salicaceae Endophytes Modulate Stomatal Behavior and Increase Water Use Efficiency in Rice

    Directory of Open Access Journals (Sweden)

    Hyungmin Rho

    2018-03-01

    Full Text Available Bacterial and yeast endophytes isolated from the Salicaceae family have been shown to promote growth and alleviate stress in plants from different taxa. To determine the physiological pathways through which endophytes affect plant water relations, we investigated leaf water potential, whole-plant water use, and stomatal responses of rice plants to Salicaceae endophyte inoculation under CO2 enrichment and water deficit. Daytime stomatal conductance and stomatal density were lower in inoculated plants compared to controls. Leaf ABA concentrations increased with endophyte inoculation. As a result, transpirational water use decreased significantly with endophyte inoculation while biomass did not change or slightly increased. This response led to a significant increase in cumulative water use efficiency at harvest. Different endophyte strains produced the same results in host plant water relations and stomatal responses. These stomatal responses were also observed under elevated CO2 conditions, and the increase in water use efficiency was more pronounced under water deficit conditions. The effect on water use efficiency was positively correlated with daily light integrals across different experiments. Our results provide insights on the physiological mechanisms of plant-endophyte interactions involving plant water relations and stomatal functions.

  9. A high CO2 -driven decrease in plant transpiration leads to perturbations in the hydrological cycle and may link terrestrial and marine loss of biodiversity: deep-time evidence.

    Science.gov (United States)

    Steinthorsdottir, Margret; Woodward, F. Ian; Surlyk, Finn; McElwain, Jennifer C.

    2013-04-01

    CO2 is obtained and water vapor simultaneously transpired through plant stomata, driving the water uptake of roots. Stomata are key elements of the Earth's hydrological cycle, since a large part of the evapotranspiration from the surface to the atmosphere takes place via stomatal pores. Plants exercise stomatal control, by adjusting stomatal size and/or density in order to preserve water while maintaining carbon uptake for photosynthesis. A global decrease in stomatal density and/or size causes a decrease in transpiration and has the potential to increase global runoff. Here we show, from 91 fossil leaf cuticle specimens from the Triassic/Jurassic boundary transition (Tr-J) of East Greenland, that both stomatal size and density decreased dramatically during the Tr-J, coinciding with mass extinctions, major environmental upheaval and a negative C-isotope excursion. We estimate that these developmental and structural changes in stomata resulted in a 50-60% drop in stomatal and canopy transpiration as calibrated using a stomatal model, based on empirical measurements and adjusted for fossil plants. We additionally present new field evidence indicating a change to increased erosion and bad-land formation at the Tr-J. We hypothesize that plant physiological responses to high carbon dioxide concentrations at the Tr-J may have increased runoff at the local and perhaps even regional scale. Increased runoff may result in increased flux of nutrients from land to oceans, leading to eutrophication, anoxia and ultimately loss of marine biodiversity. High-CO2 driven changes in stomatal and canopy transpiration therefore provide a possible mechanistic link between terrestrial ecological crisis and marine mass extinction at the Tr-J.

  10. Physiology and Regulation of Calcium Channels in Stomatal Guard Cells

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Julian I.

    2007-05-02

    Stomatal pores in the epidermis of leaves regulate the diffusion of CO2 into leaves for photosynthetic carbon fixation and control water loss of plants during drought periods. Guard cells sense CO2, water status, light and other environmental conditions to regulate stomatal apertures for optimization of CO2 intake and plant growth under drought stress. The cytosolic second messenger calcium contributes to stomatal movements by transducing signals and regulating ion channels in guard cells. Studies suggest that both plasma membrane Ca2+ influx channels and vacuolar/organellar Ca2+ release channels contribute to ABA-induced Ca2+ elevations in guard cells. Recent research in the P.I.'s laboratory has led to identification of a novel major cation-selective Ca2+-permeable influx channel (Ica) in the plasma membrane of Arabidopsis guard cells. These advances will allow detailed characterization of Ica plasma membrane Ca2+ influx channels in guard cells. The long term goal of this research project is to gain a first detailed characterization of these novel plasma membrane Ca2+-permeable channel currents in Arabidopsis guard cells. The proposed research will investigate the hypothesis that Ica represents an important Ca2+ influx pathway for ABA and CO2 signal transduction in Arabidopsis guard cells. These studies will lead to elucidation of key signal transduction mechanisms by which plants balance CO2 influx into leaves and transpirational water loss and may contribute to future strategies for manipulating gas exchange for improved growth of crop plants and for biomass production.

  11. Ozone exposure and stomatal sluggishness in different plant physiognomic classes

    Energy Technology Data Exchange (ETDEWEB)

    Paoletti, Elena, E-mail: e.paoletti@ipp.cnr.i [IPP-CNR, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, Florence (Italy); Grulke, Nancy E. [US Forest Service, 4955 Canyon Crest Drive, Riverside, CA 92507 (United States)

    2010-08-15

    Gas exchange responses to static and variable light were tested in three species: snap bean (Phaseolus vulgaris, two cultivars), California black oak (Quercus kelloggii), and blue oak (Q. douglasii). The effects of 1-month (snap beans) and 2-month (oaks) O{sub 3} (ozone) exposure (70 ppb over 8 h per day in open-top chambers) were investigated. A delay in stomatal responses (i.e., 'sluggish' responses) to variable light was found to be both an effect of O{sub 3} exposure and a reason for increased O{sub 3} sensitivity in snap bean cultivars, as it implied higher O{sub 3} uptake during times of disequilibrium. Sluggishness increased the time to open (thus limiting CO{sub 2} uptake) and close stomata (thus increasing transpirational water loss) after abrupt changes in light level. Similar responses were shown by snap beans and oaks, suggesting that O{sub 3}-induced stomatal sluggishness is a common trait among different plant physiognomic classes. - Sluggish stomatal responses are suggested to be both an effect of O{sub 3} exposure and a reason of increased O{sub 3} sensitivity in plants.

  12. Variability of stomatal conductance in a small and isolated population of silver fir (Abies alba Mill.).

    Science.gov (United States)

    Piovani, Paolo; Leonardi, Stefano; Magnani, Federico; Menozzi, Paolo

    2011-05-01

    We analyzed the response to drought of 420 individuals from eight half-sib families from a small and isolated population of silver fir (Abies alba Mill.): 105 of them were kept in well-watered conditions as control while the remaining 315 were exposed to drought for 27 days. A model describing stomatal behavior derived from Monteith and developed in beech by Leonardi et al. was fitted to experimental transpiration data obtained simply from the difference between two daily pot weighings. The estimated parameters were maximum stomatal conductance, maximum transpiration in well-watered conditions and sensitivity to soil water deficit. The model worked well: convergence for all but four individuals and concordance between experimental and fitted data were good (R(2)=0.86). Inter-individual variability for all three estimated parameters was high and two of them (maximum stomatal conductance and sensitivity to soil water deficit) were significantly different among families, suggesting genetic control. Our results validate the simplified method used to evaluate individual stomatal parameters. We also show that in the small and isolated population of our study substantial adaptive variability remains, a crucial prerequisite to endure environmental conditions determined by climatic change foreseen for the next decades. © The Author 2011. Published by Oxford University Press. All rights reserved.

  13. Convergent approaches to determine an ecosystem's transpiration fraction

    Science.gov (United States)

    Berkelhammer, M.; Noone, D. C.; Wong, T. E.; Burns, S. P.; Knowles, J. F.; Kaushik, A.; Blanken, P. D.; Williams, M. W.

    2016-06-01

    The transpiration (T) fraction of total terrestrial evapotranspiration (ET), T/ET, can vary across ecosystems between 20-95% with a global average of ˜60%. The wide range may either reflect true heterogeneity between ecosystems and/or uncertainties in the techniques used to derive this property. Here we compared independent approaches to estimate T/ET at two needleleaf forested sites with a factor of 3 difference in leaf area index (LAI). The first method utilized water vapor isotope profiles and the second derived transpiration through its functional relationship with gross primary production. We found strong agreement between T/ET values from these two independent approaches although we noted a discrepancy at low vapor pressure deficits (VPD). We hypothesize that this divergence arises because stomatal conductance is independent of humidity at low VPD. Overall, we document significant synoptic-scale T/ET variability but minimal growing season-scale variability. This result indicates a high sensitivity of T/ET to passing weather but convergence toward a stable mean state, which is set by LAI. While changes in T/ET could emerge from a myriad of processes, including aboveground (LAI) or belowground (rooting depth) changes, there was only minimal interannual variability and no secular trend in our analysis of T/ET from the 15 year eddy covariance time series at Niwot Ridge. If the lack of trend observed here is apparent elsewhere, it suggests that the processes controlling the T and E fluxes are coupled in a way to maintain a stable ratio.

  14. Stomatal closure by ultraviolet radiation

    International Nuclear Information System (INIS)

    Negash, L.; Björn, L.O.

    1986-01-01

    The effect of ultraviolet radiation (UV) (255–325 nm) on stomatal closure was investigated on tef [Eragrostis tef (Zucc) Trotter] in the presence of white light (ca 50 ·mol m −2 s −1 ). The action spectrum showed that UV (ca 2 ·mol m −2 s −1 , half band width about 10 nm) of 285 nm or shorter wavelengths was very efficient in causing stomatal closure. The effectiveness decreased sharply towards longer wavelengths. Radiation of 313 nm or longer wavelengths was practically without effect. Increasing UV intensity increased stomatal resistance. When stronger white light (5 to 9 times stronger than the one used during irradiation) was administered, stomates re-opened rapidly irrespective of whether the UV was on or off, although a subsequent gradual closing tendency was observed when the UV was on. (author)

  15. Isotopic steady state of transpired water in wheat leaves grown under different watering regimes

    Science.gov (United States)

    Hu, J.; Simonin, K.; Barbour, M.

    2013-12-01

    Stable oxygen isotopes have been used to answer a range of ecological, hydrological, and climate questions. One important application is to use oxygen isotopes to partition ecosystem evapotranspiration (ET), since the two components, transpiration and evaporation have distinctly different isotopic compositions (δ18O). However, in order to partition ET using isotopes, accurate measurements or modeling of evaporation and transpiration, are needed. Many studies use the Craig-Gordon Model to model the isotopic composition of transpired water (δ18OT), which assume plants are transpiring at isotopic steady state (ISS), such that the isotopic composition of transpired water (δ18OT) is equal to the δ18O of stem water. However, many studies are questioning the assumption that plants are transpiring at ISS, especially across diurnal time scales. A significant motivation for assuming ISS is the difficulty of collecting transpired water for isotopic analysis. However, with the introduction of laser based spectroscopy methods for isotope analysis, we can now measure δ18O of water vapor at high frequency. Furthermore, these laser based instruments can also be coupled with gas exchange systems to not only measure the isotopic composition of δ18OT, but also to examine the physiological and environmental variables that influence the isotope values, and directly test process-based models. In our study, our first objective was to assess how quickly plants reached isotopic constancy (IC) under a range of environmental conditions. We used two different wheat cultivars that had different stomatal conductance (gs) and subjected them to two different watering treatments to extend the range of gs. Our second objective was to compare δ18OT at IC with δ18O of irrigation water to understand the difference between ISS and IC. We found a significant positive relationship between gs and time to IC (pirrigation water; in other words, δ18OT never reached ISS. This has implications for

  16. Influence of stomatic aperture on photosynthetic activity of bean-seedlings leaves; Influencia de la apertura estomatica sobre la actividad fotosintetica de las hojas de plantas de judias

    Energy Technology Data Exchange (ETDEWEB)

    Suarez Moya, J.; Fernandez Gonzalez, J.

    1984-07-01

    The present paper contains the data of photosynthetic activity and stomatic aperture of bean-seedlings Ieaves, and the relations obtained with both results. It has been observed that the product of photosynthetic activity by the resistance; to transpiration measured by a promoter ia a constant, between some limits. (Author) 45 refs.

  17. The dilemma of saving water or being cool: What determines the stomatal response under a changing climate?

    Science.gov (United States)

    Haghighi, Erfan; Kirchner, James W.; Entekhabi, Dara

    2017-04-01

    Stomata play a critical role in terrestrial water and carbon cycles, regulating the trade-off between photosynthetic carbon gain and water loss in leaves. They adjust their aperture in response to a number of physiological and environmental factors, yet the mechanisms driving this response, particularly under climate extremes, remain poorly understood. Partial or complete stomatal closure reduces plant water stress under water-limited or high atmospheric evaporative demand conditions, but at the cost of reduced productivity, elevated heat, leaf shedding, and mortality. A proper account of such complex stomatal behavior is of particular importance for current ecosystem models that poorly capture observed vegetation responses in the context of climate change which is predicted to cause more frequent and intense temperature extremes along with an increase in the frequency of drought in many regions in the future. This study seeks to explore stomatal responses to environmental change accounted for by a varying soil-plant resistance under different atmospheric and soil moisture conditions. To this end, we developed a physically based transpiration model that couples stomatal control of leaf gas exchange to the leaf surface energy balance and the entire plant hydraulic system by considering the interdependence of the guard cell water potential (or turgor pressure) and transpiration rates. Model simulations of diurnal variations in transpiration rates were in good agreement with field observations, and facilitated quantitative prediction of stomatal and xylem flow regulation under a wide range of environmental conditions. Preliminary results demonstrate how soil and plant hydraulic conductances regulating stomatal opening and closure can help mitigate climatic water deficit (e.g., at midday) by boosting evaporative cooling. Our results are expected to advance physical understanding of the water cycle in the soil-plant-atmosphere continuum, and shed light on observed

  18. ABA-Mediated Stomatal Response in Regulating Water Use during the Development of Terminal Drought in Wheat.

    Science.gov (United States)

    Saradadevi, Renu; Palta, Jairo A; Siddique, Kadambot H M

    2017-01-01

    End-of-season drought or "terminal drought," which occurs after flowering, is considered the most significant abiotic stress affecting crop yields. Wheat crop production in Mediterranean-type environments is often exposed to terminal drought due to decreasing rainfall and rapid increases in temperature and evapotranspiration during spring when wheat crops enter the reproductive stage. Under such conditions, every millimeter of extra soil water extracted by the roots benefits grain filling and yield and improves water use efficiency (WUE). When terminal drought develops, soil dries from the top, exposing the top part of the root system to dry soil while the bottom part is in contact with available soil water. Plant roots sense the drying soil and produce signals, which on transmission to shoots trigger stomatal closure to regulate crop water use through transpiration. However, transpiration is linked to crop growth and productivity and limiting transpiration may reduce potential yield. While an early and high degree of stomatal closure affects photosynthesis and hence biomass production, a late and low degree of stomatal closure exhausts available soil water rapidly which results in yield losses through a reduction in post-anthesis water use. The plant hormone abscisic acid (ABA) is considered the major chemical signal involved in stomatal regulation. Wheat genotypes differ in their ability to produce ABA under drought and also in their stomatal sensitivity to ABA. In this viewpoint article we discuss the possibilities of exploiting genotypic differences in ABA response to soil drying in regulating the use of water under terminal drought. Root density distribution in the upper drying layers of the soil profile is identified as a candidate trait that can affect ABA accumulation and subsequent stomatal closure. We also examine whether leaf ABA can be designated as a surrogate characteristic for improved WUE in wheat to sustain grain yield under terminal drought. Ease

  19. Stomatal Conductance and Chlorophyll Characteristics and Their Relationship with Yield of Some Cocoa Clones Under Tectona grandis, Leucaena sp., and Cassia surattensis.

    Directory of Open Access Journals (Sweden)

    Fakhrusy Zakariyya

    2015-08-01

    Full Text Available An optimum physiological condition will support high yield and quality of cocoa production. The research was aimed to study the effects of stomatal conductance and chlorophyll content related to cocoa production under three shade regimes.This research was conducted in Kaliwining Experimental Station, elevation of 45 m above sea level with D climate type based on Schmidt & Fergusson. Cocoa trees which were planted in 1994 at a spacing of 3 X 3 m were used in the study planted by using split plot design. The shade tree species were teak (Tectona grandis, krete (Cassiasurattensis, and lamtoro (Leucaena sp. as the main plots, and cocoa clones of Sulawesi 01,Sulawesi 02, KKM 22 and KW 165 as sub plots. This study showed that there was interaction between cocoa clone and shade species for stomatal conductance where stomatal diffusive resistance of KKM 22 was the best under Leucaena sp.and Cassiasurattensis with the values of 1.38 and 1.34 s.cm -1, respectively. The highest chlorophyll content, stomatal index and transpiration values was under Leucaena sp. shade. There was positive correlation between chlorophyll content and transpiration with pod yield of cocoa. The highest yield and the lowest bean count wereobtainedon Sulawesi 01 clone under Leucaenasp. shade.Keywords: stomatal conductance, transpiration, diffusive resistance, shades trees, clones,pod yield

  20. Water-use efficiency and transpiration across European forests during the Anthropocene

    Science.gov (United States)

    Frank, D. C.; Poulter, B.; Saurer, M.; Esper, J.; Huntingford, C.; Helle, G.; Treydte, K.; Zimmermann, N. E.; Schleser, G. H.; Ahlström, A.; Ciais, P.; Friedlingstein, P.; Levis, S.; Lomas, M.; Sitch, S.; Viovy, N.; Andreu-Hayles, L.; Bednarz, Z.; Berninger, F.; Boettger, T.; D'Alessandro, C. M.; Daux, V.; Filot, M.; Grabner, M.; Gutierrez, E.; Haupt, M.; Hilasvuori, E.; Jungner, H.; Kalela-Brundin, M.; Krapiec, M.; Leuenberger, M.; Loader, N. J.; Marah, H.; Masson-Delmotte, V.; Pazdur, A.; Pawelczyk, S.; Pierre, M.; Planells, O.; Pukiene, R.; Reynolds-Henne, C. E.; Rinne, K. T.; Saracino, A.; Sonninen, E.; Stievenard, M.; Switsur, V. R.; Szczepanek, M.; Szychowska-Krapiec, E.; Todaro, L.; Waterhouse, J. S.; Weigl, M.

    2015-06-01

    The Earth's carbon and hydrologic cycles are intimately coupled by gas exchange through plant stomata. However, uncertainties in the magnitude and consequences of the physiological responses of plants to elevated CO2 in natural environments hinders modelling of terrestrial water cycling and carbon storage. Here we use annually resolved long-term δ13C tree-ring measurements across a European forest network to reconstruct the physiologically driven response of intercellular CO2 (Ci) caused by atmospheric CO2 (Ca) trends. When removing meteorological signals from the δ13C measurements, we find that trees across Europe regulated gas exchange so that for one ppmv atmospheric CO2 increase, Ci increased by ~0.76 ppmv, most consistent with moderate control towards a constant Ci/Ca ratio. This response corresponds to twentieth-century intrinsic water-use efficiency (iWUE) increases of 14 +/- 10 and 22 +/- 6% at broadleaf and coniferous sites, respectively. An ensemble of process-based global vegetation models shows similar CO2 effects on iWUE trends. Yet, when operating these models with climate drivers reintroduced, despite decreased stomatal opening, 5% increases in European forest transpiration are calculated over the twentieth century. This counterintuitive result arises from lengthened growing seasons, enhanced evaporative demand in a warming climate, and increased leaf area, which together oppose effects of CO2-induced stomatal closure. Our study questions changes to the hydrological cycle, such as reductions in transpiration and air humidity, hypothesized to result from plant responses to anthropogenic emissions.

  1. The evolution of mechanisms driving the stomatal response to vapor pressure deficit.

    Science.gov (United States)

    McAdam, Scott A M; Brodribb, Timothy J

    2015-03-01

    Stomatal responses to vapor pressure deficit (VPD) are a principal means by which vascular land plants regulate daytime transpiration. While much work has focused on characterizing and modeling this response, there remains no consensus as to the mechanism that drives it. Explanations range from passive regulation by leaf hydration to biochemical regulation by the phytohormone abscisic acid (ABA). We monitored ABA levels, leaf gas exchange, and water status in a diversity of vascular land plants exposed to a symmetrical, mild transition in VPD. The stomata in basal lineages of vascular plants, including gymnosperms, appeared to respond passively to changes in leaf water status induced by VPD perturbation, with minimal changes in foliar ABA levels and no hysteresis in stomatal action. In contrast, foliar ABA appeared to drive the stomatal response to VPD in our angiosperm samples. Increased foliar ABA level at high VPD in angiosperm species resulted in hysteresis in the recovery of stomatal conductance; this was most pronounced in herbaceous species. Increased levels of ABA in the leaf epidermis were found to originate from sites of synthesis in other parts of the leaf rather than from the guard cells themselves. The transition from a passive regulation to ABA regulation of the stomatal response to VPD in the earliest angiosperms is likely to have had critical implications for the ecological success of this lineage. © 2015 American Society of Plant Biologists. All Rights Reserved.

  2. The Evolution of Mechanisms Driving the Stomatal Response to Vapor Pressure Deficit1[OPEN

    Science.gov (United States)

    McAdam, Scott A.M.; Brodribb, Timothy J.

    2015-01-01

    Stomatal responses to vapor pressure deficit (VPD) are a principal means by which vascular land plants regulate daytime transpiration. While much work has focused on characterizing and modeling this response, there remains no consensus as to the mechanism that drives it. Explanations range from passive regulation by leaf hydration to biochemical regulation by the phytohormone abscisic acid (ABA). We monitored ABA levels, leaf gas exchange, and water status in a diversity of vascular land plants exposed to a symmetrical, mild transition in VPD. The stomata in basal lineages of vascular plants, including gymnosperms, appeared to respond passively to changes in leaf water status induced by VPD perturbation, with minimal changes in foliar ABA levels and no hysteresis in stomatal action. In contrast, foliar ABA appeared to drive the stomatal response to VPD in our angiosperm samples. Increased foliar ABA level at high VPD in angiosperm species resulted in hysteresis in the recovery of stomatal conductance; this was most pronounced in herbaceous species. Increased levels of ABA in the leaf epidermis were found to originate from sites of synthesis in other parts of the leaf rather than from the guard cells themselves. The transition from a passive regulation to ABA regulation of the stomatal response to VPD in the earliest angiosperms is likely to have had critical implications for the ecological success of this lineage. PMID:25637454

  3. Balancing Water Uptake and Loss through the Coordinated Regulation of Stomatal and Root Development.

    Directory of Open Access Journals (Sweden)

    Christopher Hepworth

    Full Text Available Root development is influenced by nutrient and water availabilities. Plants are able to adjust many attributes of their root in response to environmental signals including the size and shape of the primary root, lateral roots and root hairs. Here we investigated the response of roots to changes in the levels of leaf transpiration associated with altered stomatal frequency. We found that plants with high stomatal density and conductance produce a larger rooting area and as a result have enhanced phosphate uptake capacity whereas plants with low stomatal conductance produce a smaller root. Manipulating the growth environment of plants indicated that enhanced root growth is most likely a result of an increased demand for water rather than phosphate. Plants manipulated to have an increase or reduction in root hair growth show a reduction or increase respectively, in stomatal conductance and density. Our results demonstrate that plants can balance their water uptake and loss through coordinated regulation of both stomatal and root development.

  4. Effects of stomatal development on stomatal conductance and on stomatal limitation of photosynthesis in Syringa oblata and Euonymus japonicus Thunb.

    Science.gov (United States)

    Wu, Bing-Jie; Chow, Wah Soon; Liu, Yu-Jun; Shi, Lei; Jiang, Chuang-Dao

    2014-12-01

    During leaf development, the increase in stomatal conductance cannot meet photosynthetic demand for CO2, thus leading to stomatal limitation of photosynthesis (Ls). Considering the crucial influences of stomatal development on stomatal conductance, we speculated whether stomatal development limits photosynthesis to some extent. To test this hypothesis, stomatal development, stomatal conductance and photosynthesis were carefully studied in both Syringa oblata (normal greening species) and Euonymus japonicus Thunb (delayed greening species). Our results show that the size of stomata increased gradually with leaf expansion, resulting in increased stomatal conductance up to the time of full leaf expansion. During this process, photosynthesis also increased steadily. Compared to that in S. oblata, the development of chloroplasts in E. japonicus Thunb was obviously delayed, leading to a delay in the improvement of photosynthetic capacity. Further analysis revealed that before full leaf expansion, stomatal limitation increased rapidly in both S. oblata and E. japonicus Thunb; after full leaf expansion, stomatal limitation continually increased in E. japonicus Thunb. Accordingly, we suggested that the enhancement of photosynthetic capacity is the main factor leading to stomatal limitation during leaf development but that stomatal development can alleviate stomatal limitation with the increase of photosynthesis by controlling gas exchange. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  5. Transpiration and leaf growth of potato clones in response to soil water deficit

    Directory of Open Access Journals (Sweden)

    André Trevisan de Souza

    2014-04-01

    Full Text Available Potato (Solanum tuberosum ssp. Tuberosum crop is particularly susceptible to water deficit because of its small and shallow root system. The fraction of transpirable soil water (FTSW approach has been widely used in the evaluation of plant responses to water deficit in different crops. The FTSW 34 threshold (when stomatal closure starts is a trait of particular interest because it is an indicator of tolerance to water deficit. The FTSW threshold for decline in transpiration and leaf growth was evaluated in a drying soil to identify potato clones tolerant to water deficit. Two greenhouse experiments were carried out in pots, with three advanced clones and the cultivar Asterix. The FTSW, transpiration and leaf growth were measured on a daily basis, during the period of soil drying. FTSW was an efficient method to separate potato clones with regard to their response to water deficit. The advancedclones SMINIA 02106-11 and SMINIA 00017-6 are more tolerant to soil water deficit than the cultivar Asterix, and the clone SMINIA 793101-3 is more tolerant only under high solar radiation.

  6. Downwind evolution of transpiration by two irrigated crops under conditions of local advection

    Science.gov (United States)

    McAneney, K. J.; Brunet, Y.; Itier, B.

    1994-09-01

    Previous measurements of water loss from small-dish evaporimeters mounted at the height of irrigated crops grown under conditions of extreme local advection in the Sudan are reexamined. From these evaporimeter measurements, it is possible to calculate fractional changes in the saturation deficit. Relationships between canopy conductance and saturation deficit are briefly reviewed and introduced into the Penman-Monteith equation to calculate transpiration rates as a function of distance downwind of the boundary between the upwind desert and the irrigated crop. In contradiction to most theoretical predictions, these new calculations show rates of transpiration to undergo only modest changes with increasing fetch. This occurs because of the feedback interaction between saturation deficit and stomatal conductance. This result is in good accord with a recent study suggesting that a dry-moist boundary transition may be best modelled as a simple step change in surface fluxes and further that the advective enhancement of evaporation may have been overestimated by many advection models. Larger effects are expected on dry matter yields because of the direct influence of saturation deficit on the yield-transpiration ratio.

  7. Bayesian analysis of canopy transpiration models: A test of posterior parameter means against measurements

    Science.gov (United States)

    Mackay, D. Scott; Ewers, Brent E.; Loranty, Michael M.; Kruger, Eric L.; Samanta, Sudeep

    2012-04-01

    SummaryBig-leaf models of transpiration are based on the hypothesis that structural heterogeneity within forest canopies can be ignored at stand or larger scales. However, the adoption of big-leaf models is de facto rather than de jure, as forests are never structurally or functionally homogeneous. We tested big-leaf models both with and without modification to include canopy gaps, in a heterogeneous quaking aspen stand having a range of canopy densities. Leaf area index (L) and canopy closure were obtained from biometric data, stomatal conductance parameters were obtained from sap flux measurements, while leaf gas exchange data provided photosynthetic parameters. We then rigorously tested model-data consistency by incrementally starving the models of these measured parameters and using Bayesian Markov Chain Monte Carlo simulation to retrieve the withheld parameters. Model acceptability was quantified with Deviance Information Criterion (DIC), which penalized model accuracy by the number of retrieved parameters. Big-leaf models overestimated canopy transpiration with increasing error as canopy density declined, but models that included gaps had minimal error regardless of canopy density. When models used measured L the other parameters were retrieved with minimal bias. This showed that simple canopy models could predict transpiration in data scarce regions where only L was measured. Models that had L withheld had the lowest DIC values suggesting that they were the most acceptable models. However, these models failed to retrieve unbiased parameter estimates indicating a mismatch between model structure and data. By quantifying model structure and data requirements this new approach to evaluating model-data fusion has advanced the understanding of canopy transpiration.

  8. Relating xylem cavitation to transpiration in cotton

    Science.gov (United States)

    Acoustic emmisions (AEs) from xylem cavitation events are characteristic of transpiration processes. Even though a body of work employing AE exists with a large number of species, cotton and other agronomically important crops have either not been investigated, or limited information exists. A few s...

  9. Growth, Photosynthetic Efficiency, Rate of Transpiration, Lodging ...

    African Journals Online (AJOL)

    Growth, Photosynthetic Efficiency, Rate of Transpiration, Lodging, and Grain Yield of Tef ( Eragrostis Tef (Zucc) Trotter ) as Influenced by Stage and Rate of Paclobutrazol ... Paclobutrazol treatment had reduced plant height and total leaf area there by reduced excessive vegetative growth and lodging percentage.

  10. A phytotoxicity test using transpiration of willows

    DEFF Research Database (Denmark)

    Trapp, Stefan; Zambrano, Kim Cecilia; Kusk, Kresten Ole

    2000-01-01

    A short-term acute toxicity assay for willow trees growing in contaminated solution or in polluted soil was developed and tested. The test apparatus consists of an Erlenmeyer flask with a prerooted tree cutting growing in it. Growth and reduction of transpiration are used to determine toxicity...

  11. Terrestrial water fluxes dominated by transpiration: Comment

    Science.gov (United States)

    Daniel R. Schlaepfer; Brent E. Ewers; Bryan N. Shuman; David G. Williams; John M. Frank; William J. Massman; William K. Lauenroth

    2014-01-01

    The fraction of evapotranspiration (ET) attributed to plant transpiration (T) is an important source of uncertainty in terrestrial water fluxes and land surface modeling (Lawrence et al. 2007, Miralles et al. 2011). Jasechko et al. (2013) used stable oxygen and hydrogen isotope ratios from 73 large lakes to investigate the relative roles of evaporation (E) and T in ET...

  12. Modelled hydraulic redistribution by sunflower (Helianthus annuus L.) matches observed data only after including night-time transpiration.

    Science.gov (United States)

    Neumann, Rebecca B; Cardon, Zoe G; Teshera-Levye, Jennifer; Rockwell, Fulton E; Zwieniecki, Maciej A; Holbrook, N Michele

    2014-04-01

    The movement of water from moist to dry soil layers through the root systems of plants, referred to as hydraulic redistribution (HR), occurs throughout the world and is thought to influence carbon and water budgets and ecosystem functioning. The realized hydrologic, biogeochemical and ecological consequences of HR depend on the amount of redistributed water, whereas the ability to assess these impacts requires models that correctly capture HR magnitude and timing. Using several soil types and two ecotypes of sunflower (Helianthus annuus L.) in split-pot experiments, we examined how well the widely used HR modelling formulation developed by Ryel et al. matched experimental determination of HR across a range of water potential driving gradients. H. annuus carries out extensive night-time transpiration, and although over the last decade it has become more widely recognized that night-time transpiration occurs in multiple species and many ecosystems, the original Ryel et al. formulation does not include the effect of night-time transpiration on HR. We developed and added a representation of night-time transpiration into the formulation, and only then was the model able to capture the dynamics and magnitude of HR we observed as soils dried and night-time stomatal behaviour changed, both influencing HR. © 2013 John Wiley & Sons Ltd.

  13. Leaf temperature and stomatal influences on sap velocity diurnal hysteresis in the Amazon rainforest

    Science.gov (United States)

    Jardine, K.; Gimenez, B.; Negron Juarez, R. I.; Koven, C.; Powell, T.; Higuchi, N.; Chambers, J.; Varadharajan, C.

    2016-12-01

    In order to improve our ability to predict terrestrial evapotranspiration fluxes, an understanding of the interactions between plant physiology and environmental conditions is necessary, but remains poorly characterized, especially in tropical ecosystems. In this study we show a tight positive correlation between sap velocity (at 1 m of height) and leaf surface temperature (LST, 20-30 m of height) in canopy dominant trees in two primary rainforest sites in the Amazon basin (Santarém and Manaus, Brazil). As leaf temperatures varied throughout the day, sap velocity responded with little delay (<15 min). Positive sap velocity was often observed at night, but also closely followed night time LSTs. When plotted versus LST, sap velocity showed an exponential increase before reaching a reflection point and a plateau and is characterized as a sigmoidal curve, in all observed trees. Moreover, a clear diurnal hysteresis in sap velocity was evident with morning periods showing higher temperature sensitivities than afternoon and night periods. Diurnal leaf observations showed a morning peak in stomatal conductance ( 10:00-10:30), but a mid-day to afternoon peak in transpiration and leaf temperature (12:00-14:00). Our observations suggest the sap velocity-LST hysteresis pattern arises due to the temporal offset between stomatal conductance and vapor pressure deficits (VPD) and demonstrates the dominating effect of VPD over stomatal conductance in maintaining high transpiration/sap flow rates under elevated temperatures. Our results have important implications for modeling tropical forest transpiration and suggests the possibility of predicting evapotranspiration fluxes at the ecosystem to regional scales based on remote sensed vegetation temperature.

  14. Carbon and hydrogen isotopic effects of stomatal density in Arabidopsis thaliana

    Science.gov (United States)

    Lee, Hyejung; Feakins, Sarah J.; Sternberg, Leonel da S. L.

    2016-04-01

    Stomata are key gateways mediating carbon uptake and water loss from plants. Varied stomatal densities in fossil leaves raise the possibility that isotope effects associated with the openness of exchange may have mediated plant wax biomarker isotopic proxies for paleovegetation and paleoclimate in the geological record. Here we use Arabidopsis thaliana, a widely used model organism, to provide the first controlled tests of stomatal density on carbon and hydrogen isotopic compositions of cuticular waxes. Laboratory grown wildtype and mutants with suppressed and overexpressed stomatal densities allow us to directly test the isotope effects of stomatal densities independent of most other environmental or biological variables. Hydrogen isotope (D/H) measurements of both plant waters and plant wax n-alkanes allow us to directly constrain the isotopic effects of leaf water isotopic enrichment via transpiration and biosynthetic fractionations, which together determine the net fractionation between irrigation water and n-alkane hydrogen isotopic composition. We also measure carbon isotopic fractionations of n-alkanes and bulk leaf tissue associated with different stomatal densities. We find offsets of +15‰ for δD and -3‰ for δ13C for the overexpressed mutant compared to the suppressed mutant. Since the range of stomatal densities expressed is comparable to that found in extant plants and the Cenozoic fossil record, the results allow us to consider the magnitude of isotope effects that may be incurred by these plant adaptive responses. This study highlights the potential of genetic mutants to isolate individual isotope effects and add to our fundamental understanding of how genetics and physiology influence plant biochemicals including plant wax biomarkers.

  15. A Raf-like protein kinase BHP mediates blue light-dependent stomatal opening.

    Science.gov (United States)

    Hayashi, Maki; Inoue, Shin-Ichiro; Ueno, Yoshihisa; Kinoshita, Toshinori

    2017-03-30

    Stomata in the plant epidermis open in response to blue light and affect photosynthesis and plant growth by regulating CO 2 uptake and transpiration. In stomatal guard cells under blue light, plasma membrane H + -ATPase is phosphorylated and activated via blue light-receptor phototropins and a signaling mediator BLUS1, and H + -ATPase activation drives stomatal opening. However, details of the signaling between phototropins and H + -ATPase remain largely unknown. In this study, through a screening of specific inhibitors for the blue light-dependent H + -ATPase phosphorylation in guard cells, we identified a Raf-like protein kinase, BLUE LIGHT-DEPENDENT H + -ATPASE PHOSPHORYLATION (BHP). Guard cells in the bhp mutant showed impairments of stomatal opening and H + -ATPase phosphorylation in response to blue light. BHP is abundantly expressed in the cytosol of guard cells and interacts with BLUS1 both in vitro and in vivo. Based on these results, BHP is a novel signaling mediator in blue light-dependent stomatal opening, likely downstream of BLUS1.

  16. In situ observation of stomatal movements and gas exchange of Aegopodium podagraria L. in the understorey.

    Science.gov (United States)

    Kaiser, H; Kappen, L

    2000-10-01

    Observations of stomata in situ while simultaneously measuring CO(2) gas exchange and transpiration were made in field experiments with Aegopodium podagraria in a highly variable light climate in the understorey of trees. The low background photosynthetic photon flux density (PPFD) caused a slight opening of the stomata and no visible response to sporadic lightflecks. However, if lightflecks were frequent and brighter, slow opening movements were observed. Small apertures were sufficient to allow maximal photosynthetic rates. Therefore, the small apertures observed in low light usually only caused minor stomatal limitations of lightfleck photosynthesis. The response of stomata to step-wise changes in PPFD under different levels of leaf to air vapour pressure difference (Delta(W)) was observed under controlled conditions. High Delta(W) influenced the stomatal response only slightly by reducing stomatal aperture in low light and causing a slight reduction in the initial capacity to utilize high PPFD levels. Under continuous high PPFD, however, stomata opened to the same degree irrespective of Delta(W). Under high Delta(W), opening and closing responses to PPFD-changes were faster, which enabled a rapid removal of the small stomatal limitations of photosynthesis initially present in high Delta(W) after longer periods in low light. It is concluded that A. podagraria maintains a superoptimal aperture in low light which leads to a low instantaneous water use efficiency, but allows an efficient utilization of randomly occurring lightflecks.

  17. Effect of canopy architectural variation on transpiration and thermoregulation

    Science.gov (United States)

    Linn, R.; Banerjee, T.

    2017-12-01

    One of the major scientific questions identified by the NGEE - Tropics campaign is the effect of disturbances such as forest fires, vegetation thinning and land use change on carbon, water and energy fluxes. Answers to such questions can help develop effective forest management strategies and shape policies to mitigate damages under natural and anthropogenic climate change. The absence of horizontal and vertical variation of forest canopy structure in current models is a major source of uncertainty in answering these questions. The current work addresses this issue through a bottom up process based modeling approach to systematically investigate the effect of forest canopy architectural variation on plant physiological response as well as canopy level fluxes. A plant biophysics formulation is used which is based on the following principles: (1) a model for the biochemical demand for CO2 as prescribed by photosynthesis models. This model can differentiate between photosynthesis under light-limited and nutrient-limited scenarios. (2) A Fickian mass transfer model including transfer through the laminar boundary layer on leaves that may be subjected to forced or free convection depending upon the mean velocity and the radiation load; (3) an optimal leaf water use strategy that maximizes net carbon gain for a given transpiration rate to describe the stomatal aperture variation; (4) a leaf-level energy balance to accommodate evaporative cooling. Such leaf level processes are coupled to solutions of atmospheric flow through vegetation canopies. In the first test case, different scenarios of top heavy and bottom heavy (vertical) foliage distributions are investigated within a one-dimensional framework where no horizontal heterogeneity of canopy structure is considered. In another test case, different spatial distributions (both horizontal and vertical) of canopy geometry (land use) are considered, where flow solutions using large eddy simulations (LES) are coupled to the

  18. Allergic contact stomatitis from colophony.

    Science.gov (United States)

    Sharma, Paul R

    2006-09-01

    Colophony is an ubiquitous contact sensitizer which may be present in dental materials, such as periodontal dressings, impression materials, cements, fix adhesives and varnishes. Exposure to a sensitizer in a hypersensitive person may initiate an allergic contact dermatitis/stomatitis. This usually occurs after direct skin/mucosa contact with the sensitizer. This paper reports the case of a colophony hypersensitive male who developed contact stomatitis after dental treatment with a colophony-containing product. Sensitizing colophony is present in Duraphat 2.26%F varnish, a fluoride varnish used all over the world. A case of hypersensitivity to Duraphat 2.26%F varnish is presented in a patient who, at the initial visit, indicated only an allergy to sticking plasters.

  19. Evaporative demand, transpiration, and photosynthesis: How are they changing?

    Science.gov (United States)

    Farquhar, G. D.; Roderick, M. L.

    2009-04-01

    Carbon dioxide concentration is increasing. This affects photosynthesis via increases in substrate availability (Farquhar et al. 1980). It reduces the amount of water transpired by plants to fix a given amount of carbon into an organic form; i.e it increases transpiration efficiency (Wong et al. 1979). It also warms the earth's surface. It is commonly supposed that this warming causes an increase in evaporative demand - the rate of water loss from a wet surface. This supposition has then been extended to effects on plant water availability, with the idea that there would be offsets to the gains in productivity associated with increased transpiration efficiency. The assumption that increased temperature means increased evaporative demand has also been applied to global maps of changes in soil water content. However, observations of pan evaporation rate show that this measure of evaporative demand has been decreasing in most areas examined over the last few decades. We reconcile these observations with theory by noting that, on long time scales, warming also involves water bodies, so that the vapour pressure at the earth's surface also increases. Using the physics of pan evaporation (Rotstayn et al. 2006) we show that the reduction in evaporative demand has been associated with two main effects, (1) "dimming", a reduction in sunlight received at the earth's surface because of aerosols and clouds, being the first phenomenon identified (Roderick and Farquhar 2002), and (2) "stilling", a reduction in wind speed, being the second (Roderick et al. 2007). We show that better accounting for changes in evaporative demand is important for estimating soil water changes, particularly in regions where precipitation exceeds evaporative demand (i.e where there are rivers) (Hobbins et al. 2008). We synthesise some of these results with others on vegetation change. References: Farquhar, GD, von Caemmerer, S, and Berry, JA, 1980: A biochemical model of photosynthetic CO2 assimilation

  20. Water relations and transpiration of quinoa (Chenopodium quinoa Willd.) under salinity and soil drying

    DEFF Research Database (Denmark)

    Razzaghi, Fatemeh; Ahmadi, Seyed Hamid; Adolf, Verena Isabelle

    2011-01-01

    Drought and salinity are the two major factors limiting crop growth and production in arid and semi-arid regions. The separate and combined effects of salinity and progressive drought in quinoa (Chenopodium quinoa Willd.) were studied in a greenhouse experiment. Stomatal conductance (gs), leaf...... values in both FI and PD. During the drought period, the xylem [ABA] extracted from the shoots increased faster than that extracted from the roots. A reduction in WT, caused by salinity and soil drying, reduced transpiration and increased apparent root resistance (R) to water uptake, especially in PD0.......42 or lower, but under the saline conditions of PD10 and PD20, the threshold values of RAW were 0.67 and 0.96, respectively. In conclusion, due to the additive effect of osmotic and matric potential during soil drying on soil water availability, quinoa should be re-irrigated at higher RAW in salt...

  1. Stomatal Conductance, Plant Hydraulics, and Multilayer Canopies: A New Paradigm for Earth System Models or Unnecessary Uncertainty

    Science.gov (United States)

    Bonan, G. B.

    2016-12-01

    Soil moisture stress is a key regulator of canopy transpiration, the surface energy budget, and land-atmosphere coupling. Many land surface models used in Earth system models have an ad-hoc parameterization of soil moisture stress that decreases stomatal conductance with soil drying. Parameterization of soil moisture stress from more fundamental principles of plant hydrodynamics is a key research frontier for land surface models. While the biophysical and physiological foundations of such parameterizations are well-known, their best implementation in land surface models is less clear. Land surface models utilize a big-leaf canopy parameterization (or two big-leaves to represent the sunlit and shaded canopy) without vertical gradients in the canopy. However, there are strong biometeorological and physiological gradients in plant canopies. Are these gradients necessary to resolve? Here, I describe a vertically-resolved, multilayer canopy model that calculates leaf temperature and energy fluxes, photosynthesis, stomatal conductance, and leaf water potential at each level in the canopy. In this model, midday leaf water stress manifests in the upper canopy layers, which receive high amounts of solar radiation, have high leaf nitrogen and photosynthetic capacity, and have high stomatal conductance and transpiration rates (in the absence of leaf water stress). Lower levels in the canopy become water stressed in response to longer-term soil moisture drying. I examine the role of vertical gradients in the canopy microclimate (solar radiation, air temperature, vapor pressure, wind speed), structure (leaf area density), and physiology (leaf nitrogen, photosynthetic capacity, stomatal conductance) in determining above canopy fluxes and gradients of transpiration and leaf water potential within the canopy.

  2. Data Driven Estimation of Transpiration from Net Water Fluxes: the TEA Algorithm

    Science.gov (United States)

    Nelson, J. A.; Carvalhais, N.; Cuntz, M.; Delpierre, N.; Knauer, J.; Migliavacca, M.; Ogee, J.; Reichstein, M.; Jung, M.

    2017-12-01

    The eddy covariance method, while powerful, can only provide a net accounting of ecosystem fluxes. Particularly with water cycle components, efforts to partitioning total evapotranspiration (ET) into the biotic component (transpiration, T) and the abiotic component (here evaporation, E) have seen limited success, with no one method emerging as a standard.Here we demonstrate a novel method that uses ecosystem WUE to predict transpiration in two steps: (1) a filtration step that to isolate the signal of ET for periods where E is minimized and ET is likely dominated by the signal of T; and (2) a step which predicts the WUE using meteorological variables, as well as information derived from the carbon and energy fluxes. To assess the the underlying assumptions, we tested the proposed method on three ecological models, allowing validation where the underlying carbon:water relationships, as well as the transpiration estimates, are know.The partitioning method shows high correlation (R²>0.8) between Tmodel/ET and TTEA/ET across timescales from half-hourly to annually, as well as capturing spatial variability across sites. Apart from predictive performance, we explore the sensitivities of the method to the underlying assumptions, such as the effects of residual evaporation in the training dataset. Furthermore, we show initial transpiration estimates from the algorithm at global scale, via the FLUXNET dataset.

  3. Coordination of stomatal physiological behavior and morphology with carbon dioxide determines stomatal control.

    Science.gov (United States)

    Haworth, Matthew; Killi, Dilek; Materassi, Alessandro; Raschi, Antonio

    2015-05-01

    Stomatal control is determined by the ability to alter stomatal aperture and/or the number of stomata on the surface of new leaves in response to growth conditions. The development of stomatal control mechanisms to the concentration of CO₂within the atmosphere ([CO₂]) is fundamental to our understanding of plant evolutionary history and the prediction of gas exchange responses to future [CO₂]. In a controlled environment, fern and angiosperm species were grown in atmospheres of ambient (400 ppm) and elevated (2000 ppm) [CO₂]. Physiological stomatal behavior was compared with the stomatal morphological response to [CO₂]. An increase in [CO₂] or darkness induced physiological stomatal responses ranging from reductions (active) to no change (passive) in stomatal conductance. Those species with passive stomatal behavior exhibited pronounced reductions of stomatal density in new foliage when grown in elevated [CO₂], whereas species with active stomata showed little morphological response to [CO₂]. Analysis of the physiological and morphological stomatal responses of a wider range of species suggests that patterns of stomatal control to [CO₂] do not follow a phylogenetic pattern associated with plant evolution. Selective pressures may have driven the development of divergent stomatal control strategies to increased [CO₂]. Those species that are able to actively regulate guard cell turgor are more likely to respond to [CO₂] through a change in stomatal aperture than stomatal number. We propose a model of stomatal control strategies in response to [CO₂] characterized by a trade-off between short-term physiological behavior and longer-term morphological response. © 2015 Botanical Society of America, Inc.

  4. TaER Expression Is Associated with Transpiration Efficiency Traits and Yield in Bread Wheat

    Science.gov (United States)

    Zheng, Jiacheng; Yang, Zhiyuan; Madgwick, Pippa J.; Carmo-Silva, Elizabete; Parry, Martin A. J.; Hu, Yin-Gang

    2015-01-01

    ERECTA encodes a receptor-like kinase and is proposed as a candidate for determining transpiration efficiency of plants. Two genes homologous to ERECTA in Arabidopsis were identified on chromosomes 6 (TaER2) and 7 (TaER1) of bread wheat (Triticum aestivum L.), with copies of each gene on the A, B and D genomes of wheat. Similar expression patterns were observed for TaER1 and TaER2 with relatively higher expression of TaER1 in flag leaves of wheat at heading (Z55) and grain-filling (Z73) stages. Significant variations were found in the expression levels of both TaER1 and TaER2 in the flag leaves at both growth stages among 48 diverse bread wheat varieties. Based on the expression of TaER1 and TaER2, the 48 wheat varieties could be classified into three groups having high (5 varieties), medium (27 varieties) and low (16 varieties) levels of TaER expression. Significant differences were also observed between the three groups varying for TaER expression for several transpiration efficiency (TE)- related traits, including stomatal density (SD), transpiration rate, photosynthetic rate (A), instant water use efficiency (WUEi) and carbon isotope discrimination (CID), and yield traits of biomass production plant-1 (BYPP) and grain yield plant-1 (GYPP). Correlation analysis revealed that the expression of TaER1 and TaER2 at the two growth stages was significantly and negatively associated with SD (Pwheat, implying a function for TaER in regulating leaf development of bread wheat and contributing to expression of these traits. Moreover, the results indicate that TaER could be exploitable for manipulating important agronomical traits in wheat improvement. PMID:26047019

  5. Transpiration of shrub species, Alnus firma under changing atmospheric environments in montane area, Japan

    Science.gov (United States)

    Miyazawa, Y.; Maruyama, A.; Inoue, A.

    2014-12-01

    In the large caldera of Mt. Aso in Japan, grasslands have been traditionally managed by the farmers. Due to changes in the social structure of the region, a large area of the grassland has been abandoned and was invaded by the shrubs with different hydrological and ecophysiological traits. Ecophysiological traits and their responses to seasonally changing environments are fundamental to project the transpiration rates under changing air and soil water environments, but less is understood. We measured the tree- and leaf-level ecophysiological traits of a shrub, Alnus firma in montane region where both rainfall and soil water content drastically changes seasonally. Sap flux reached the annual peak in evaporative summer (July-August) both in 2013 and 2014, although the duration was limited within a short period due to the prolonged rainy season before summer (2014) and rapid decrease in the air vapor pressure deficit (D) in late summer. Leaf ecophysiological traits in close relationship with gas exchange showed modest seasonal changes and the values were kept at relatively high levels typical in plants with nitrogen fixation under nutrient-poor environments. Stomatal conductance, which was measured at leaf-level measurements and sap flux measurements, showed responses to D, which coincided with the theoretical response for isohydric leaves. A multilayer model, which estimates stand-level transpiration by scaling up the leaf-level data, successfully captured the temporal trends in sap flux, suggesting that major processes were incorporated. Thus, ecophysiological traits of A. firma were characterized by the absence of responses to seasonally changing environments and the transpiration rate was the function of the interannually variable environmental conditions.

  6. Modeling stomatal conductance in the earth system: linking leaf water-use efficiency and water transport along the soil-plant-atmosphere continuum

    Science.gov (United States)

    Bonan, G. B.; Williams, M.; Fisher, R. A.; Oleson, K. W.

    2014-09-01

    The Ball-Berry stomatal conductance model is commonly used in earth system models to simulate biotic regulation of evapotranspiration. However, the dependence of stomatal conductance (gs) on vapor pressure deficit (Ds) and soil moisture must be empirically parameterized. We evaluated the Ball-Berry model used in the Community Land Model version 4.5 (CLM4.5) and an alternative stomatal conductance model that links leaf gas exchange, plant hydraulic constraints, and the soil-plant-atmosphere continuum (SPA). The SPA model simulates stomatal conductance numerically by (1) optimizing photosynthetic carbon gain per unit water loss while (2) constraining stomatal opening to prevent leaf water potential from dropping below a critical minimum. We evaluated two optimization algorithms: intrinsic water-use efficiency (ΔAn /Δgs, the marginal carbon gain of stomatal opening) and water-use efficiency (ΔAn /ΔEl, the marginal carbon gain of transpiration water loss). We implemented the stomatal models in a multi-layer plant canopy model to resolve profiles of gas exchange, leaf water potential, and plant hydraulics within the canopy, and evaluated the simulations using leaf analyses, eddy covariance fluxes at six forest sites, and parameter sensitivity analyses. The primary differences among stomatal models relate to soil moisture stress and vapor pressure deficit responses. Without soil moisture stress, the performance of the SPA stomatal model was comparable to or slightly better than the CLM Ball-Berry model in flux tower simulations, but was significantly better than the CLM Ball-Berry model when there was soil moisture stress. Functional dependence of gs on soil moisture emerged from water flow along the soil-to-leaf pathway rather than being imposed a priori, as in the CLM Ball-Berry model. Similar functional dependence of gs on Ds emerged from the ΔAn/ΔEl optimization, but not the ΔAn /gs optimization. Two parameters (stomatal efficiency and root hydraulic

  7. Heat exchanger with transpired, highly porous fins

    Science.gov (United States)

    Kutscher, Charles F.; Gawlik, Keith

    2002-01-01

    The heat exchanger includes a fin and tube assembly with increased heat transfer surface area positioned within a hollow chamber of a housing to provide effective heat transfer between a gas flowing within the hollow chamber and a fluid flowing in the fin and tube assembly. A fan is included to force a gas, such as air, to flow through the hollow chamber and through the fin and tube assembly. The fin and tube assembly comprises fluid conduits to direct the fluid through the heat exchanger, to prevent mixing with the gas, and to provide a heat transfer surface or pathway between the fluid and the gas. A heat transfer element is provided in the fin and tube assembly to provide extended heat transfer surfaces for the fluid conduits. The heat transfer element is corrugated to form fins between alternating ridges and grooves that define flow channels for directing the gas flow. The fins are fabricated from a thin, heat conductive material containing numerous orifices or pores for transpiring the gas out of the flow channel. The grooves are closed or only partially open so that all or substantially all of the gas is transpired through the fins so that heat is exchanged on the front and back surfaces of the fins and also within the interior of the orifices, thereby significantly increasing the available the heat transfer surface of the heat exchanger. The transpired fins also increase heat transfer effectiveness of the heat exchanger by increasing the heat transfer coefficient by disrupting boundary layer development on the fins and by establishing other beneficial gas flow patterns, all at desirable pressure drops.

  8. Optimal stomatal behaviour around the world

    DEFF Research Database (Denmark)

    Lin, Yan-Shih; Medlyn, Belinda E.; Duursma, Remko A.

    2015-01-01

    , a globalscale database and an associated globally applicable model of gs that allow predictions of stomatal behaviour are lacking. Here,we present a database of globally distributed gs obtained in the field for a wide range of plant functional types (PFTs) and biomes. We find that stomatal behaviour diers among...

  9. ABA-Mediated Stomatal Response in Regulating Water Use during the Development of Terminal Drought in Wheat

    Directory of Open Access Journals (Sweden)

    Renu Saradadevi

    2017-07-01

    Full Text Available End-of-season drought or “terminal drought,” which occurs after flowering, is considered the most significant abiotic stress affecting crop yields. Wheat crop production in Mediterranean-type environments is often exposed to terminal drought due to decreasing rainfall and rapid increases in temperature and evapotranspiration during spring when wheat crops enter the reproductive stage. Under such conditions, every millimeter of extra soil water extracted by the roots benefits grain filling and yield and improves water use efficiency (WUE. When terminal drought develops, soil dries from the top, exposing the top part of the root system to dry soil while the bottom part is in contact with available soil water. Plant roots sense the drying soil and produce signals, which on transmission to shoots trigger stomatal closure to regulate crop water use through transpiration. However, transpiration is linked to crop growth and productivity and limiting transpiration may reduce potential yield. While an early and high degree of stomatal closure affects photosynthesis and hence biomass production, a late and low degree of stomatal closure exhausts available soil water rapidly which results in yield losses through a reduction in post-anthesis water use. The plant hormone abscisic acid (ABA is considered the major chemical signal involved in stomatal regulation. Wheat genotypes differ in their ability to produce ABA under drought and also in their stomatal sensitivity to ABA. In this viewpoint article we discuss the possibilities of exploiting genotypic differences in ABA response to soil drying in regulating the use of water under terminal drought. Root density distribution in the upper drying layers of the soil profile is identified as a candidate trait that can affect ABA accumulation and subsequent stomatal closure. We also examine whether leaf ABA can be designated as a surrogate characteristic for improved WUE in wheat to sustain grain yield under

  10. Daily transpiration rates of woody species on drying soil.

    Science.gov (United States)

    Sinclair, Thomas R; Holbrook, N Michelle; Zwieniecki, Maciej A

    2005-11-01

    Among annual plants, daily transpiration rates, expressed as a fraction of volumetric soil water content available for transpiration, show a common pattern in response to soil drying. Initially, as soil dries, there is little decrease in transpiration rate until water availability has fallen to about one third that at field capacity. With further soil drying, relative transpiration rate decreases in a more-or-less linear fashion until all available water has been used. Data previously obtained for perennial woody species have often been confounded by different methods for determining available soil water. In this study, we investigated the daily transpiration response to soil drying in five woody perennial species: Thuja plicata Donn ex D. Don, Acer rubrum L., Robinia pseudoacacia L., Hibiscus sp. and Ibex aquifolium L. Transpiration was unaffected by soil drying until the initial estimated transpirable soil water fraction had decreased to between 0.23 and 0.32 of that at field capacity. Beyond this point, transpiration rate declined linearly with available soil water fraction until reaching one fifth the rate observed in well-watered plants. With further soil drying, the relative transpiration rates remained between 10 and 20% of that observed in well-watered plants. Maintenance of transpiration at these rates with further soil drying was hypothesized to result from contributions to transpiration of water stored in plant tissues. After taking tissue water storage into account, it was estimated that transpiration was curtailed as the available soil water fraction fell to between 0.26 and 0.37 of that at field capacity, which is comparable to values reported for annual crop plants.

  11. Chlorella induces stomatal closure via NADPH oxidase-dependent ROS production and its effects on instantaneous water use efficiency in Vicia faba.

    Directory of Open Access Journals (Sweden)

    Yan Li

    Full Text Available Reactive oxygen species (ROS have been established to participate in stomatal closure induced by live microbes and microbe-associated molecular patterns (MAMPs. Chlorella as a beneficial microorganism can be expected to trigger stomatal closure via ROS production. Here, we reported that Chlorella induced stomatal closure in a dose-and time-dependent manner in epidermal peels of Vicia faba. Using pharmacological methods in this work, we found that the Chlorella-induced stomatal closure was almost completely abolished by a hydrogen peroxide (H2O2 scavenger, catalase (CAT, significantly suppressed by an NADPH oxidase inhibitor, diphenylene iodonium chloride (DPI, and slightly affected by a peroxidase inhibitor, salicylhydroxamic acid (SHAM, suggesting that ROS production involved in Chlorella-induced stomatal closure is mainly mediated by DPI-sensitive NADPH oxidase. Additionally, Exogenous application of optimal concentrations of Chlorella suspension improved instantaneous water use efficiency (WUEi in Vicia faba via a reduction in leaf transpiration rate (E without a parallel reduction in net photosynthetic rate (Pn assessed by gas-exchange measurements. The chlorophyll fluorescence and content analysis further demonstrated that short-term use of Chlorella did not influence plant photosynthetic reactions center. These results preliminarily reveal that Chlorella can trigger stomatal closure via NADPH oxidase-dependent ROS production in epidermal strips and improve WUEi in leave levels.

  12. Chlorella induces stomatal closure via NADPH oxidase-dependent ROS production and its effects on instantaneous water use efficiency in Vicia faba.

    Science.gov (United States)

    Li, Yan; Xu, Shan-Shan; Gao, Jing; Pan, Sha; Wang, Gen-Xuan

    2014-01-01

    Reactive oxygen species (ROS) have been established to participate in stomatal closure induced by live microbes and microbe-associated molecular patterns (MAMPs). Chlorella as a beneficial microorganism can be expected to trigger stomatal closure via ROS production. Here, we reported that Chlorella induced stomatal closure in a dose-and time-dependent manner in epidermal peels of Vicia faba. Using pharmacological methods in this work, we found that the Chlorella-induced stomatal closure was almost completely abolished by a hydrogen peroxide (H2O2) scavenger, catalase (CAT), significantly suppressed by an NADPH oxidase inhibitor, diphenylene iodonium chloride (DPI), and slightly affected by a peroxidase inhibitor, salicylhydroxamic acid (SHAM), suggesting that ROS production involved in Chlorella-induced stomatal closure is mainly mediated by DPI-sensitive NADPH oxidase. Additionally, Exogenous application of optimal concentrations of Chlorella suspension improved instantaneous water use efficiency (WUEi) in Vicia faba via a reduction in leaf transpiration rate (E) without a parallel reduction in net photosynthetic rate (Pn) assessed by gas-exchange measurements. The chlorophyll fluorescence and content analysis further demonstrated that short-term use of Chlorella did not influence plant photosynthetic reactions center. These results preliminarily reveal that Chlorella can trigger stomatal closure via NADPH oxidase-dependent ROS production in epidermal strips and improve WUEi in leave levels.

  13. Regulatory mechanism controlling stomatal behavior conserved across 400 million years of land plant evolution.

    Science.gov (United States)

    Chater, Caspar; Kamisugi, Yasuko; Movahedi, Mahsa; Fleming, Andrew; Cuming, Andrew C; Gray, Julie E; Beerling, David J

    2011-06-21

    Stomatal pores evolved more than 410 million years ago [1, 2] and allowed vascular plants to regulate transpirational water loss during the uptake of CO(2) for photosynthesis [3]. Here, we show that stomata on the sporophytes of the moss Physcomitrella patens [2] respond to environmental signals in a similar way to those of flowering plants [4] and that a homolog of a key signaling component in the vascular plant drought hormone abscisic acid (ABA) response [5] is involved in stomatal control in mosses. Cross-species complementation experiments reveal that the stomatal ABA response of a flowering plant (Arabidopsis thaliana) mutant, lacking the ABA-regulatory protein kinase OPEN STOMATA 1 (OST1) [6], is rescued by substitution with the moss P. patens homolog, PpOST1-1, which evolved more than 400 million years earlier. We further demonstrate through the targeted knockout of the PpOST1-1 gene in P. patens that its role in guard cell closure is conserved, with stomata of mutant mosses exhibiting a significantly attenuated ABA response. Our analyses indicate that core regulatory components involved in guard cell ABA signaling of flowering plants are operational in mosses and likely originated in the last common ancestor of these lineages more than 400 million years ago [7], prior to the evolution of ferns [8, 9]. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Origins and Evolution of Stomatal Development.

    Science.gov (United States)

    Chater, Caspar C C; Caine, Robert S; Fleming, Andrew J; Gray, Julie E

    2017-06-01

    The fossil record suggests stomata-like pores were present on the surfaces of land plants over 400 million years ago. Whether stomata arose once or whether they arose independently across newly evolving land plant lineages has long been a matter of debate. In Arabidopsis, a genetic toolbox has been identified that tightly controls stomatal development and patterning. This includes the basic helix-loop-helix (bHLH) transcription factors SPEECHLESS ( SPCH ), MUTE , FAMA , and ICE/SCREAMs ( SCRMs ), which promote stomatal formation. These factors are regulated via a signaling cascade, which includes mobile EPIDERMAL PATTERNING FACTOR ( EPF ) peptides to enforce stomatal spacing. Mosses and hornworts, the most ancient extant lineages to possess stomata, possess orthologs of these Arabidopsis ( Arabidopsis thaliana ) stomatal toolbox genes, and manipulation in the model bryophyte Physcomitrella patens has shown that the bHLH and EPF components are also required for moss stomatal development and patterning. This supports an ancient and tightly conserved genetic origin of stomata. Here, we review recent discoveries and, by interrogating newly available plant genomes, we advance the story of stomatal development and patterning across land plant evolution. Furthermore, we identify potential orthologs of the key toolbox genes in a hornwort, further supporting a single ancient genetic origin of stomata in the ancestor to all stomatous land plants. © 2017 American Society of Plant Biologists. All Rights Reserved.

  15. Global separation of plant transpiration from groundwater and streamflow

    Science.gov (United States)

    Jaivime Evaristo; Scott Jasechko; Jeffrey J. McDonnell

    2015-01-01

    Current land surface models assume that groundwater, streamflow and plant transpiration are all sourced and mediated by the same well mixed water reservoir—the soil. However, recent work in Oregon and Mexico has shown evidence of ecohydrological separation, whereby different subsurface compartmentalized pools of water supply either plant transpiration fluxes or the...

  16. Effects of increased atmospheric CO{sub 2} concentrations on transpiration of a wheat field in consideration of water and nitrogen limitation; Die Wirkung von erhoehten atmosphaerischen CO{sub 2}-Konzentrationen auf die Transpiration eines Weizenbestandes unter Beruecksichtigung von Wasser- und Stickstofflimitierung

    Energy Technology Data Exchange (ETDEWEB)

    Grossman-Clarke, S.

    2000-09-01

    Primary responses of C{sub 3}-plants to elevated atmospheric CO{sub 2} concentrations are an increase in the net assimilation rate, leading to greater biomass, and an associated decrease in the transpiration rate per unit leaf area due to CO{sub 2}-induced stomatal closure. The question has therefore arisen: does canopy transpiration increase because of the greater biomass, or decrease because of the stomatal closure? The direct impact of an elevated atmospheric CO{sub 2} concentration of 550 {mu}mol mol{sup -1} on the seasonal course of canopy transpiration of a spring wheat crop was investigated by means of the simulation model DEMETER for production under unlimited water and nutrient supply, production under limited water but unlimited nutrient supply and the production under unlimited water but limited nitrogen supply. Independent data of the free-air carbon dioxide enrichment wheat experiments in Arizona, USA (1993-96) were used to test if the model is able to make reasonable predictions of water use and productivity of the spring wheat crop using only parameters derived from the literature. A model integrating leaf photosynthesis, stomatal conductance and energy fluxes between the plant and the atmosphere was scaled to a canopy level in order to be used in the wheat crop growth model. Temporal changes of the model parameters were considered by describing them as dependent on the changing leaf nitrogen content. Comparison of the simulation and experimental results showed that the applicability of the model approach was limited after anthesis by asynchronous changes in mesophyll and stomatal conductance. Therefore a new model approach was developed describing the interaction between assimilation rate and stomatal conductance during grain filling. The simulation results revealed only small differences in the cumulative sum of canopy transpiration and soil evaporation between elevated CO{sub 2} and control conditions. For potential growth conditions the model

  17. Ecology of Candida-associated Denture Stomatitis

    OpenAIRE

    Budtz-Jørgensen, Ejvind

    2011-01-01

    Introduction of a prosthesis into the oral cavity results in profound alterations of the environmental conditions as the prosthesis and the underlying mucosa become colonized with oral microorganisms, including Candida spp. This may lead to denture stomatitis, a non-specific inflammatory reaction against microbial antigens, toxins and enzymes produced by the colonizing microorganisms. The role of Candida in the etiology of denture stomatitis is indicated by an increased number of yeasts on th...

  18. Prevention of Stomatitis: Using Dexamethasone-Based Mouthwash to Inhibit Everolimus-Related Stomatitis

    Science.gov (United States)

    Saigal, Babita; Guerra, Laura

    2018-04-01

    A common class-specific toxicity of mammalian target of rapamycin (mTOR) inhibitors is stomatitis. Some patients experience a severe form of mTOR inhibitor-associated stomatitis (mIAS) that can have a negative effect on nutritional status, compromise quality of life, and potentially lead to nonadherence, reducing the efficacy of cancer therapy. This article aims to address an unmet need for education about mIAS among oncology nurses and patients and to share findings about everolimus-related stomatitis from the SWISH trial. The authors reviewed the literature on mIAS and selected a case series of experiences to illustrate successes and clinical challenges that an oncology nurse might encounter when caring for patients with advanced breast cancer who may develop everolimus-related stomatitis. Recommendations are provided for oncology nurses to educate patients on prevention, early detection, monitoring, and management strategies to mitigate the incidence and severity of everolimus-related stomatitis.

  19. Evidence-based modelling of diverse plant water use strategies on stomatal and non-stomatal components under drought

    Science.gov (United States)

    zhou, S.; Prentice, C.; Medlyn, B. E.; Sabaté, S.

    2013-12-01

    Models disagree on how to represent effects of drought stress on plant gas exchange. Some models assume drought stress affects the marginal water use efficiency of plants (marginal WUE; i.e. the change in photosynthesis per unit of change in transpiration) whereas others assume drought stress acts directly on photosynthetic capacity. It is not clear whether either of these approaches is sufficient to capture the drought response, or whether the effect of drought varies among species and functional types. A collection of Eucalyptus and Quercus species derived from different hydro-climate habitats, in together with two European riparian species, were conducted with drought treatments respectively in Australia and Spain for three months. Measurements included net CO2 assimilation rate versus substomatal CO2 concentration (A-Ci) curves, fluorescence, and predawn leaf water potential at increasing levels of water stress. The correlations with quantitative plant traits of leaf, stomata, vessel, and wood density, leaf nitrogen content and 13C discrimination were also explored. We analysed the effect of drought effect on leaf gas exchange with a recently developed stomatal model that reconciles the empirical and optimal approaches on predicting optimal stomatal conductance. The model's single parameter g1 is a decreasing function of marginal WUE. The two genera showed consistence on the contrasting response patterns between species derived from mesic and arid habitats, which differed greatly in their estimated g1 values under moist conditions, and in the rate at which g1 declined with water stress. They also differed greatly in the predawn water potential at which apparent carboxylation capacity (apparent Vcmax) and mesophyll conductance (gm) declined most steeply, and in the steepness of this decline. Principal components analysis revealed a gradient in water relation strategies from sclerophyll species to malacophyll species. Malacophylls had higher g1, apparent Vcmax

  20. Drought response in wheat: key genes and regulatory mechanisms controlling root system architecture and transpiration efficiency

    Science.gov (United States)

    Kulkarni, Manoj; Soolanayakanahally, Raju; Ogawa, Satoshi; Uga, Yusaku; Selvaraj, Michael G.; Kagale, Sateesh

    2017-12-01

    Abiotic stresses such as drought, heat, salinity and flooding threaten global food security. Crop genetic improvement with increased resilience to abiotic stresses is a critical component of crop breeding strategies. Wheat is an important cereal crop and a staple food source globally. Enhanced drought tolerance in wheat is critical for sustainable food production and global food security. Recent advances in drought tolerance research have uncovered many key genes and transcription regulators governing morpho-physiological traits. Genes controlling root architecture and stomatal development play an important role in soil moisture extraction and its retention, and therefore have been targets of molecular breeding strategies for improving drought tolerance. In this systematic review, we have summarized evidence of beneficial contributions of root and stomatal traits to plant adaptation to drought stress. Specifically, we discuss a few key genes such as DRO1 in rice and ERECTA in Arabidopsis and rice that were identified to be the enhancers of drought tolerance via regulation of root traits and transpiration efficiency. Additionally, we highlight several transcription factor families, such as ERF (ethylene response factors), DREB (dehydration responsive element binding), ZFP (zinc finger proteins), WRKY and MYB that were identified to be both positive and negative regulators of drought responses in wheat, rice, maize and/or Arabidopsis. The overall aim of this review was to provide an overview of candidate genes that have been tested as regulators of drought response in plants. The lack of a reference genome sequence for wheat and nontransgenic approaches for manipulation of gene functions in the past had impeded high-resolution interrogation of functional elements, including genes and QTLs, and their application in cultivar improvement. The recent developments in wheat genomics and reverse genetics, including the availability of a gold-standard reference genome

  1. Constraining Ecosystem Gross Primary Production and Transpiration with Measurements of Photosynthetic 13CO2 Discrimination

    Science.gov (United States)

    Blonquist, J. M.; Wingate, L.; Ogeé, J.; Bowling, D. R.

    2011-12-01

    The stable carbon isotope composition of atmospheric CO2 (δ13Ca) can provide useful information on water use efficiency (WUE) dynamics of terrestrial ecosystems and potentially constrain models of CO2 and water fluxes at the land surface. This is due to the leaf-level relationship between photosynthetic 13CO2 discrimination (Δ), which influences δ13Ca, and the ratio of leaf intercellular to atmospheric CO2 mole fractions (Ci / Ca), which is related to WUE and is determined by the balance between C assimilation (CO2 demand) and stomatal conductance (CO2 supply). We used branch-scale Δ derived from tunable diode laser absorption spectroscopy measurements collected in a Maritime pine forest to estimate Ci / Ca variations over an entire growing season. We combined Ci / Ca estimates with rates of gross primary production (GPP) derived from eddy covariance (EC) to estimate canopy-scale stomatal conductance (Gs) and transpiration (T). Estimates of T were highly correlated to T estimates derived from sapflow data (y = 1.22x + 0.08; r2 = 0.61; slope P MuSICA) (y = 0.88x - 0.05; r2 = 0.64; slope P MuSICA (y = 1.10 + 0.42; r2 = 0.50; slope P < 0.001). Results demonstrate that the leaf-level relationship between Δ and Ci / Ca can be extended to the canopy-scale and that Δ measurements have utility for partitioning ecosystem-scale CO2 and water fluxes.

  2. Intraspecific variation in stomatal traits, leaf traits and physiology reflects adaptation along aridity gradients in a South African shrub.

    Science.gov (United States)

    Carlson, Jane E; Adams, Christopher A; Holsinger, Kent E

    2016-01-01

    increasing transpiration and cooling, but predominately in drier, hotter climates. This study uniquely shows context-dependent benefits of stomatal density--a trait rarely linked to local adaptation in plants. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. A novel bHLH transcription factor PebHLH35 from Populus euphratica confers drought tolerance through regulating stomatal development, photosynthesis and growth in Arabidopsis

    International Nuclear Information System (INIS)

    Dong, Yan; Wang, Congpeng; Han, Xiao; Tang, Sha; Liu, Sha; Xia, Xinli; Yin, Weilun

    2014-01-01

    Highlights: • PebHLH35 is firstly cloned from Populus euphratica and characterized its functions. • PebHLH35 is important for earlier seedling establishment and vegetative growth. • PebHLH35 enhances tolerance to drought by regulating growth. • PebHLH35 enhances tolerance to drought by regulating stomatal development. • PebHLH35 enhances tolerance to drought by regulating photosynthesis and transpiration. - Abstract: Plant basic helix-loop-helix (bHLH) transcription factors (TFs) are involved in a variety of physiological processes including the regulation of plant responses to various abiotic stresses. However, few drought-responsive bHLH family members in Populus have been reported. In this study, a novel bHLH gene (PebHLH35) was cloned from Populus euphratica. Expression analysis in P. euphratica revealed that PebHLH35 was induced by drought and abscisic acid. Subcellular localization studies using a PebHLH35-GFP fusion showed that the protein was localized to the nucleus. Ectopic overexpression of PebHLH35 in Arabidopsis resulted in a longer primary root, more leaves, and a greater leaf area under well-watered conditions compared with vector control plants. Notably, PebHLH35 overexpression lines showed enhanced tolerance to water-deficit stress. This finding was supported by anatomical and physiological analyses, which revealed a reduced stomatal density, stomatal aperture, transpiration rate, and water loss, and a higher chlorophyll content and photosynthetic rate. Our results suggest that PebHLH35 functions as a positive regulator of drought stress responses by regulating stomatal density, stomatal aperture, photosynthesis and growth

  4. A novel bHLH transcription factor PebHLH35 from Populus euphratica confers drought tolerance through regulating stomatal development, photosynthesis and growth in Arabidopsis

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Yan [College of Biological Sciences and Technology, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083 (China); Liaoning Forestry Vocational-Technical College, Shenyang 110101 (China); Wang, Congpeng; Han, Xiao; Tang, Sha; Liu, Sha [College of Biological Sciences and Technology, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083 (China); Xia, Xinli, E-mail: xiaxl@bjfu.edu.cn [College of Biological Sciences and Technology, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083 (China); Yin, Weilun, E-mail: yinwl@bjfu.edu.cn [College of Biological Sciences and Technology, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083 (China)

    2014-07-18

    Highlights: • PebHLH35 is firstly cloned from Populus euphratica and characterized its functions. • PebHLH35 is important for earlier seedling establishment and vegetative growth. • PebHLH35 enhances tolerance to drought by regulating growth. • PebHLH35 enhances tolerance to drought by regulating stomatal development. • PebHLH35 enhances tolerance to drought by regulating photosynthesis and transpiration. - Abstract: Plant basic helix-loop-helix (bHLH) transcription factors (TFs) are involved in a variety of physiological processes including the regulation of plant responses to various abiotic stresses. However, few drought-responsive bHLH family members in Populus have been reported. In this study, a novel bHLH gene (PebHLH35) was cloned from Populus euphratica. Expression analysis in P. euphratica revealed that PebHLH35 was induced by drought and abscisic acid. Subcellular localization studies using a PebHLH35-GFP fusion showed that the protein was localized to the nucleus. Ectopic overexpression of PebHLH35 in Arabidopsis resulted in a longer primary root, more leaves, and a greater leaf area under well-watered conditions compared with vector control plants. Notably, PebHLH35 overexpression lines showed enhanced tolerance to water-deficit stress. This finding was supported by anatomical and physiological analyses, which revealed a reduced stomatal density, stomatal aperture, transpiration rate, and water loss, and a higher chlorophyll content and photosynthetic rate. Our results suggest that PebHLH35 functions as a positive regulator of drought stress responses by regulating stomatal density, stomatal aperture, photosynthesis and growth.

  5. Leaf hydraulic conductance declines in coordination with photosynthesis, transpiration and leaf water status as soybean leaves age regardless of soil moisture

    Science.gov (United States)

    Locke, Anna M.; Ort, Donald R.

    2014-01-01

    Photosynthesis requires sufficient water transport through leaves for stomata to remain open as water transpires from the leaf, allowing CO2 to diffuse into the leaf. The leaf water needs of soybean change over time because of large microenvironment changes over their lifespan, as leaves mature in full sun at the top of the canopy and then become progressively shaded by younger leaves developing above. Leaf hydraulic conductance (K leaf), a measure of the leaf’s water transport capacity, can often be linked to changes in microenvironment and transpiration demand. In this study, we tested the hypothesis that K leaf would decline in coordination with transpiration demand as soybean leaves matured and aged. Photosynthesis (A), stomatal conductance (g s) and leaf water potential (Ψleaf) were also measured at various leaf ages with both field- and chamber-grown soybeans to assess transpiration demand. K leaf was found to decrease as soybean leaves aged from maturity to shading to senescence, and this decrease was strongly correlated with midday A. Decreases in K leaf were further correlated with decreases in g s, although the relationship was not as strong as that with A. Separate experiments investigating the response of K leaf to drought demonstrated no acclimation of K leaf to drought conditions to protect against cavitation or loss of g s during drought and confirmed the effect of leaf age in K leaf observed in the field. These results suggest that the decline of leaf hydraulic conductance as leaves age keeps hydraulic supply in balance with demand without K leaf becoming limiting to transpiration water flux. PMID:25281701

  6. Genetic effects on transpiration, canopy conductance, stomatal sensitivity to vapour pressure deficit, and cavitation resistance in loblolly pine

    Science.gov (United States)

    Michael J Aspinwall; John S King; Jean-Christophe Domec; Steven E McKeand; Isik Fikret

    2011-01-01

    Physiological uniformity and genetic effects on canopy-level gas-exchange and hydraulic function could impact loblolly pine (Pinus taeda L.) plantation sustainability and ecosystem dynamics under projected changes in climate. Over a 1-year period, we examined genetic effects on mean and maximum mid-day canopy conductance (Gs, Gsmax...

  7. Phreatophytes under stress: transpiration and stomatal conductance of saltcedar (Tamarix spp.) in a high-salinity environment

    Science.gov (United States)

    Glenn, Edward P.; Nagler, Pamela L.; Morino, Kiyomi; Hultine, Kevin

    2013-01-01

    Background and aims: We sought to understand the environmental constraints on an arid-zone riparian phreatophtye, saltcedar (Tamarix ramosissima and related species and hybrids), growing over a brackish aquifer along the Colorado River in the western U.S. Depth to groundwater, meteorological factors, salinity and soil hydraulic properties were compared at stress and non-stressed sites that differed in salinity of the aquifer, soil properties and water use characteristics, to identify the factors depressing water use at the stress site.

  8. Low doses of glyphosate enhance growth, CO2 assimilation, stomatal conductance and transpiration in sugarcane and eucalyptus

    Science.gov (United States)

    Sublethal doses of herbicides can enhance plant growth and stimulate other process, an effect known as hormesis. The magnitude of hormesis is dependent on the plant species, the herbicide and its dose, plant development stage, and environmental parameters. Glyphosate hormesis is well established, bu...

  9. Stomatal and Non-Stomatal Turbulent Deposition Flux of Ozone to a Managed Peatland

    Directory of Open Access Journals (Sweden)

    Tarek S. El-Madany

    2017-09-01

    Full Text Available Ozone is a key trace gas in the troposphere; because it is a greenhouse gas, it is very reactive, and it is potentially toxic to humans, fauna, and vegetation. The main sink processes for ozone are chemical reactions and the turbulent deposition flux to the earth’s surface. The deposition process itself is rather complex: The interactions between co-varying drivers such as the tropospheric ozone concentration, turbulence, and chemical reactions are not well understood. In the case of ozone deposition to vegetation, another aspect that must be studied is the role of stomatal regulation for a wide range of conditions. Therefore, we measured turbulent deposition fluxes of ozone with the eddy covariance technique during the peak of the growing season in 2014 over a managed, rewetted peatland in NW Germany. The deposition flux was large during the day (up to −15 nmol m−2 s−1 and relatively small during the night (between −1 and −2 nmol m−2 s−1. Flux partitioning by applying the surface resistance analogy and further analysis showed that the stomatal uptake was smaller than non-stomatal deposition. The correction of stomatal conductance with the gross primary production (GPP improved the estimation of day- and nighttime stomatal deposition fluxes. Statistical analysis confirmed that the friction velocity (u* was the single most important driver of non-stomatal ozone deposition and that relationships with other environmental drivers are not linear and highly variable. Further research is needed to develop a better process understanding of non-stomatal ozone deposition, to quantify the role of surface deposition to the ozone budget of the atmospheric boundary layer, and to estimate uncertainties associated with the partitioning of ozone deposition into stomatal and non-stomatal fluxes.

  10. Stomatal and non-stomatal factors regulated the photosynthesis of soybean seedlings in the present of exogenous bisphenol A.

    Science.gov (United States)

    Jiao, Liya; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

    2017-11-01

    Bisphenol A (BPA) is an emerging environmental endocrine disruptor that has toxic effects on plants growth. Photosynthesis supplies the substances and energy required for plant growth, and regulated by stomatal and non-stomatal factors. Therefore, in this study, to reveal how BPA affects photosynthesis in soybean seedlings (Glycine max L.) from the perspective of stomatal and non-stomatal factors, the stomatal factors (stomatal conductance and behaviours) and non-stomatal factors (Hill reaction, apparent quantum efficiency, Rubisco activity, carboxylation efficiency, the maximum Rubisco carboxylation velocity, ribulose-1,5-bisphospate regeneration capacities mediated by maximum electron transport rates, and triose phosphate utilization rate) were investigated using a portable photosynthesis system. Moreover, the pollution of BPA in the environment was simulated. The results indicate that low-dose BPA enhanced net photosynthetic rate (P n ) primarily by promoting stomatal factors, resulting in increased relative growth rates and accelerated soybean seedling growth. High-dose BPA decreases the P n by simultaneously inhibiting stomatal and non-stomatal factors, and this inhibition decreases the relative growth rates further reducing soybean seedling growth. Following the withdrawal of BPA, all of the indices were restored to varying degrees. In conclusion, low-dose BPA increased the P n by promoting stomatal factors while high-dose BPA decreased the P n by simultaneously inhibiting stomatal and non-stomatal factors. These findings provide a model (or, hypothesis) for the effects of BPA on plant photosynthesis. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Stomatal characteristics of Eucalyptus grandis clonal hybrids in ...

    African Journals Online (AJOL)

    This study describes the stomatal response occurring during water stress and subsequent recovery of three Eucalyptus grandis clonal hybrids. The aim was to investigate the degree to which stomatal conductance (gs) and stomatal density differ between the clonal hybrids across seasons and in response to water stress.

  12. Within-catchment variation in regulation of water use by eucalypts, and the roles of stomatal anatomy and physiology

    Science.gov (United States)

    Gharun, Mana; Turnbull, Tarryn; Adams, Mark

    2014-05-01

    Understanding how environmental cues impact water use of forested catchments is crucial for accurate calculation of water balance and effective catchment management in terrestrial ecosystems. We characterised structural and physiological properties of leaves and canopies of Eucalyptus delegatensis, E. pauciflora and E. radiata, the most common species in high-country catchments in temperate Australia. These properties were related to whole-tree water transport to assess differences in water use strategies among the three species. Stomatal conductance, instantaneous transpiration efficiency, stomatal occlusion (through cuticular ledges) and leaf area index differed significantly among species. Whole-tree water use of all species was strongly coupled to changes in vapour pressure deficit (VPD) and photosynthetically active radiation (Q), yet stomatal closure reduced water transport at VPD > 1 kPa in all species, even when soil water was not limiting. The observed differences in leaf traits and related water use strategies reflect species-specific adaptations to dominant environmental conditions within the landscape matrix of catchments. The generalist E. radiata seems to follow an opportunistic, while the two more spatially restricted species have adopted a pessimistic water use strategy. Catchment-scale models of carbon and water fluxes will need to reflect such variation in structure and function, if they are to fully capture species effects on water balance and yield.

  13. Oxygen isotope signatures of transpired water vapor: the role of isotopic non-steady-state transpiration under natural conditions.

    Science.gov (United States)

    Dubbert, Maren; Cuntz, Matthias; Piayda, Arndt; Werner, Christiane

    2014-09-01

    The oxygen isotope signature of water is a powerful tracer of water movement from plants to the global scale. However, little is known about the short-term variability of oxygen isotopes leaving the ecosystem via transpiration, as high-frequency measurements are lacking. A laser spectrometer was coupled to a gas-exchange chamber directly estimating branch-level fluxes in order to evaluate the short-term variability of the isotopic composition of transpiration (δE ) and to investigate the role of isotopic non-steady-state transpiration under natural conditions in cork-oak trees (Quercus suber) during distinct Mediterranean seasons. The measured δ(18) O of transpiration (δE ) deviated from isotopic steady state throughout most of the day even when leaf water at the evaporating sites was near isotopic steady state. High agreement was found between estimated and modeled δE values assuming non-steady-state enrichment of leaf water. Isoforcing, that is, the influence of the transpirational δ(18) O flux on atmospheric values, deviated from steady-state calculations but daily means were similar between steady state and non-steady state. However, strong daytime isoforcing on the atmosphere implies that short-term variations in δE are likely to have consequences for large-scale applications, for example, partitioning of ecosystem fluxes or satellite-based applications. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  14. Coupling gross primary production and transpiration for a consistent estimate of canopy water use efficiency

    Science.gov (United States)

    Yebra, Marta; van Dijk, Albert

    2015-04-01

    Water use efficiency (WUE, the amount of transpiration or evapotranspiration per unit gross (GPP) or net CO2 uptake) is key in all areas of plant production and forest management applications. Therefore, mutually consistent estimates of GPP and transpiration are needed to analysed WUE without introducing any artefacts that might arise by combining independently derived GPP and ET estimates. GPP and transpiration are physiologically linked at ecosystem level by the canopy conductance (Gc). Estimates of Gc can be obtained by scaling stomatal conductance (Kelliher et al. 1995) or inferred from ecosystem level measurements of gas exchange (Baldocchi et al., 2008). To derive large-scale or indeed global estimates of Gc, satellite remote sensing based methods are needed. In a previous study, we used water vapour flux estimates derived from eddy covariance flux tower measurements at 16 Fluxnet sites world-wide to develop a method to estimate Gc using MODIS reflectance observations (Yebra et al. 2013). We combined those estimates with the Penman-Monteith combination equation to derive transpiration (T). The resulting T estimates compared favourably with flux tower estimates (R2=0.82, RMSE=29.8 W m-2). Moreover, the method allowed a single parameterisation for all land cover types, which avoids artefacts resulting from land cover classification. In subsequent research (Yebra et al, in preparation) we used the same satellite-derived Gc values within a process-based but simple canopy GPP model to constrain GPP predictions. The developed model uses a 'big-leaf' description of the plant canopy to estimate the mean GPP flux as the lesser of a conductance-limited and radiation-limited GPP rate. The conductance-limited rate was derived assuming that transport of CO2 from the bulk air to the intercellular leaf space is limited by molecular diffusion through the stomata. The radiation-limited rate was estimated assuming that it is proportional to the absorbed photosynthetically

  15. Modeling productivity and transpiration of Pinus radiata: climatic effects

    Energy Technology Data Exchange (ETDEWEB)

    Sheriff, D. W.; Mattay, J. P. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Canberra, ACT (Australia). Div. of Forestry and Forest Products; McMurtrie, R. E. [New South Wales Univ., Sydney, NSW (Australia)

    1996-01-01

    Using a process-based forest growth model, BIOMASS, the climatic effect on annual net carbon gain, stem biomass and annual transpiration were simulated for Pinus radiata. Regional variation in climate between Canberra and Mt. Gambier resulted in a 20 per cent difference in simulated annual transpiration rate, but only a relatively small difference in simulated productivity. Simulated carbon gain values averaged about 1.4 per cent; this result was not consistent with the predicted 8 per cent annual carbon assimilation difference between the two sites, based on differences in climate. These results suggest that climatic differences do not account for differences in productivity. 12 refs., 3 tabs., 2 figs.

  16. Resource use and efficiency, and stomatal responses to environmental drivers of oak and pine species in an Atlantic Coastal Plain forest

    Directory of Open Access Journals (Sweden)

    Heidi J Renninger

    2015-05-01

    Full Text Available Pine-oak ecosystems are globally distributed even though differences in anatomy and leaf habit between many co-occurring oaks and pines suggest different strategies for resource use, efficiency and stomatal behavior. The New Jersey Pinelands contain sandy soils with low water- and nutrient-holding capacity providing an opportunity to examine trade-offs in resource uptake and efficiency. Therefore, we compared resource use in terms of transpiration rates and leaf nitrogen content and resource-use efficiency including water-use efficiency (WUE via gas exchange and leaf carbon isotopes and photosynthetic nitrogen-use efficiency (PNUE between oaks (Quercus alba, Q. prinus, Q. velutina and pines (Pinus rigida, P. echinata. We also determined environmental drivers (vapor pressure deficit (VPD, soil moisture, solar radiation of canopy stomatal conductance (GS estimated via sap flow and stomatal sensitivity to light and soil moisture. Net assimilation rates were similar between genera, but oak leaves used about 10% more water and pine foliage contained about 20% more N per unit leaf area. Therefore, oaks exhibited greater PNUE while pines had higher WUE based on gas exchange, although WUE from carbon isotopes was not significantly different. For the environmental drivers of GS, oaks had about 10% lower stomatal sensitivity to VPD normalized by reference stomatal conductance compared with pines. Pines exhibited a significant positive relationship between shallow soil moisture and GS, but only GS in Q. velutina was positively related to soil moisture. In contrast, stomatal sensitivity to VPD was significantly related to solar radiation in all oak species but only pines at one site. Therefore, oaks rely more heavily on groundwater resources but have lower WUE, while pines have larger leaf areas and nitrogen acquisition but lower PNUE demonstrating a trade-off between using water and nitrogen efficiently in a resource-limited ecosystem.

  17. Sequence and function of basic helix-loop-helix proteins required for stomatal development in Arabidopsis are deeply conserved in land plants.

    Science.gov (United States)

    MacAlister, Cora A; Bergmann, Dominique C

    2011-01-01

    Stomata are a broadly conserved feature of land plants with a crucial role regulating transpiration and gas exchange between the plant and atmosphere. Stereotyped cell divisions within a specialized cell lineage of the epidermis generate stomata and define the pattern of their distribution. The behavior of the stomatal lineage varies in its detail among different plant groups, but general features include asymmetric cell divisions and an immediate precursor (the guard mother cell [GMC]) that divides symmetrically to form the pair of cells that will differentiate into the guard cells. In Arabidopsis, the closely related basic helix-loop-helix (bHLH) subgroup Ia transcription factors SPEECHLESS, MUTE, and FAMA promote asymmetric divisions, the acquisition of GMC identity and guard cell differentiation, respectively. Genome sequence data indicate that these key positive regulators of stomatal development are broadly conserved among land plants. While orthologies can be established among individual family members within the angiosperms, more distantly related groups contain subgroup Ia bHLHs of unclear affinity. We demonstrate group Ia members from the moss Physcomitrella patens can partially complement MUTE and FAMA and recapitulate gain of function phenotypes of group Ia genes in multiple steps in the stomatal lineage in Arabidopsis. Our data are consistent with a mechanism whereby a multifunctional transcription factor underwent duplication followed by specialization to provide the three (now nonoverlapping) functions of the angiosperm stomatal bHLHs. © 2011 Wiley Periodicals, Inc.

  18. The K+ channel KZM2 is involved in stomatal movement by modulating inward K+ currents in maize guard cells.

    Science.gov (United States)

    Gao, Yong-Qiang; Wu, Wei-Hua; Wang, Yi

    2017-11-01

    Stomata are the major gates in plant leaf that allow water and gas exchange, which is essential for plant transpiration and photosynthesis. Stomatal movement is mainly controlled by the ion channels and transporters in guard cells. In Arabidopsis, the inward Shaker K + channels, such as KAT1 and KAT2, are responsible for stomatal opening. However, the characterization of inward K + channels in maize guard cells is limited. In the present study, we identified two KAT1-like Shaker K + channels, KZM2 and KZM3, which were highly expressed in maize guard cells. Subcellular analysis indicated that KZM2 and KZM3 can localize at the plasma membrane. Electrophysiological characterization in HEK293 cells revealed that both KZM2 and KZM3 were inward K + (K in ) channels, but showing distinct channel kinetics. When expressed in Xenopus oocytes, only KZM3, but not KZM2, can mediate inward K + currents. However, KZM2 can interact with KZM3 forming heteromeric K in channel. In oocytes, KZM2 inhibited KZM3 channel conductance and negatively shifted the voltage dependence of KZM3. The activation of KZM2-KZM3 heteromeric channel became slower than the KZM3 channel. Patch-clamping results showed that the inward K + currents of maize guard cells were significantly increased in the KZM2 RNAi lines. In addition, the RNAi lines exhibited faster stomatal opening after light exposure. In conclusion, the presented results demonstrate that KZM2 functions as a negative regulator to modulate the K in channels in maize guard cells. KZM2 and KZM3 may form heteromeric K in channel and control stomatal opening in maize. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  19. Vesicular stomatitis forecasting based on Google Trends.

    Science.gov (United States)

    Wang, JianYing; Zhang, Tong; Lu, Yi; Zhou, GuangYa; Chen, Qin; Niu, Bing

    2018-01-01

    Vesicular stomatitis (VS) is an important viral disease of livestock. The main feature of VS is irregular blisters that occur on the lips, tongue, oral mucosa, hoof crown and nipple. Humans can also be infected with vesicular stomatitis and develop meningitis. This study analyses 2014 American VS outbreaks in order to accurately predict vesicular stomatitis outbreak trends. American VS outbreaks data were collected from OIE. The data for VS keywords were obtained by inputting 24 disease-related keywords into Google Trends. After calculating the Pearson and Spearman correlation coefficients, it was found that there was a relationship between outbreaks and keywords derived from Google Trends. Finally, the predicted model was constructed based on qualitative classification and quantitative regression. For the regression model, the Pearson correlation coefficients between the predicted outbreaks and actual outbreaks are 0.953 and 0.948, respectively. For the qualitative classification model, we constructed five classification predictive models and chose the best classification predictive model as the result. The results showed, SN (sensitivity), SP (specificity) and ACC (prediction accuracy) values of the best classification predictive model are 78.52%,72.5% and 77.14%, respectively. This study applied Google search data to construct a qualitative classification model and a quantitative regression model. The results show that the method is effective and that these two models obtain more accurate forecast.

  20. Vesicular stomatitis forecasting based on Google Trends

    Science.gov (United States)

    Lu, Yi; Zhou, GuangYa; Chen, Qin

    2018-01-01

    Background Vesicular stomatitis (VS) is an important viral disease of livestock. The main feature of VS is irregular blisters that occur on the lips, tongue, oral mucosa, hoof crown and nipple. Humans can also be infected with vesicular stomatitis and develop meningitis. This study analyses 2014 American VS outbreaks in order to accurately predict vesicular stomatitis outbreak trends. Methods American VS outbreaks data were collected from OIE. The data for VS keywords were obtained by inputting 24 disease-related keywords into Google Trends. After calculating the Pearson and Spearman correlation coefficients, it was found that there was a relationship between outbreaks and keywords derived from Google Trends. Finally, the predicted model was constructed based on qualitative classification and quantitative regression. Results For the regression model, the Pearson correlation coefficients between the predicted outbreaks and actual outbreaks are 0.953 and 0.948, respectively. For the qualitative classification model, we constructed five classification predictive models and chose the best classification predictive model as the result. The results showed, SN (sensitivity), SP (specificity) and ACC (prediction accuracy) values of the best classification predictive model are 78.52%,72.5% and 77.14%, respectively. Conclusion This study applied Google search data to construct a qualitative classification model and a quantitative regression model. The results show that the method is effective and that these two models obtain more accurate forecast. PMID:29385198

  1. Vesicular stomatitis forecasting based on Google Trends.

    Directory of Open Access Journals (Sweden)

    JianYing Wang

    Full Text Available Vesicular stomatitis (VS is an important viral disease of livestock. The main feature of VS is irregular blisters that occur on the lips, tongue, oral mucosa, hoof crown and nipple. Humans can also be infected with vesicular stomatitis and develop meningitis. This study analyses 2014 American VS outbreaks in order to accurately predict vesicular stomatitis outbreak trends.American VS outbreaks data were collected from OIE. The data for VS keywords were obtained by inputting 24 disease-related keywords into Google Trends. After calculating the Pearson and Spearman correlation coefficients, it was found that there was a relationship between outbreaks and keywords derived from Google Trends. Finally, the predicted model was constructed based on qualitative classification and quantitative regression.For the regression model, the Pearson correlation coefficients between the predicted outbreaks and actual outbreaks are 0.953 and 0.948, respectively. For the qualitative classification model, we constructed five classification predictive models and chose the best classification predictive model as the result. The results showed, SN (sensitivity, SP (specificity and ACC (prediction accuracy values of the best classification predictive model are 78.52%,72.5% and 77.14%, respectively.This study applied Google search data to construct a qualitative classification model and a quantitative regression model. The results show that the method is effective and that these two models obtain more accurate forecast.

  2. Revisiting the contribution of transpiration to global terrestrial evapotranspiration

    NARCIS (Netherlands)

    Wei, Zhongwang; Yoshimura, Kei; Wang, Lixin; Miralles, Diego G.; Jasechko, Scott; Lee, Xuhui

    2017-01-01

    Even though knowing the contributions of transpiration (T), soil and open water evaporation (E), and interception (I) to terrestrial evapotranspiration (ET = T + E + I) is crucial for understanding the hydrological cycle and its connection to ecological processes, the fraction of T is unattainable

  3. respiration and transpiration characteristics of selected fresh fruits

    African Journals Online (AJOL)

    AISA

    Respiration and transpiration characteristics of mushrooms, strawberries, broccoli and tomatoes were determined under different temperature, atmospheric and humidity conditions in order to get information for modified humidity atmosphere conception. The respiration rate was determined using a static method. (scanning ...

  4. Partitioning evapotranspiration into evaporation and transpiration in a corn field

    Science.gov (United States)

    Evapotranspiration (ET) is a main component of the hydrology cycle. It consists of soil water evaporation (E) and plant transpiration (T). Accurate partitioning of ET into E and T is challenging. We measured soil water E using heat pulse sensors and a micro-Bowen ratio system, T using stem flow gaug...

  5. Entropy production and plant transpiration in the Liz catchment

    Czech Academy of Sciences Publication Activity Database

    Šír, Miloslav; Tesař, Miroslav; Krejča, M.; Weger, J.

    2008-01-01

    Roč. 1, č. 1 (2008), s. 81-89 ISSN 1802-503X Grant - others:MŠMT(CZ) 2B06132 Institutional research plan: CEZ:AV0Z20600510 Keywords : plant transpiration * phytomass productivity * heat balance * entropy production Subject RIV: DA - Hydrology ; Limnology

  6. The effect of grass transpiration on the air temperature

    Czech Academy of Sciences Publication Activity Database

    Šír, M.; Tesař, Miroslav; Lichner, Ľ.; Czachor, H.

    2014-01-01

    Roč. 69, č. 11 (2014), s. 1570-1576 ISSN 0006-3088 Institutional support: RVO:67985874 Keywords : air temperature oscillations * embolism * plant transpiration * soil water * tensiometric pressure * xylem tension Subject RIV: DA - Hydrology ; Limnology Impact factor: 0.827, year: 2014

  7. The transpiration cooled first wall and blanket concept

    International Nuclear Information System (INIS)

    Barleon, Leopold; Wong, Clement

    2002-01-01

    To achieve high thermal performance at high power density the EVOLVE concept was investigated under the APEX program. The EVOLVE W-alloy first wall and blanket concept proposes to use transpiration cooling of the first wall and boiling or vaporizing lithium (Li) in the blanket zone. Critical issues of this concept are: the Magnetohydrodynamic (MHD) pressure losses of the Li circuit, the evaporation through a capillary structure and the needed superheating of the Li at the first wall and blanket zones. Application of the transpiration concept to the blanket region results in the integrated transpiration cooling concept (ITCC) with either toroidal or poloidal first wall channels. For both orientations the routing of the liquid Li and the Li vapor has been modeled and the corresponding pressure losses have been calculated by varying the width of the supplying slot and the capillary diameter. The concept works when the sum of the active and passive pumping head is higher than the total system pressure losses and when the temperature at the inner side of the first wall does not override the superheating limit of the coolant. This cooling concept has been extended to the divertor design, and the removal of a surface heat flux of up to 10 MW/m 2 appears to be possible, but this paper will focus on the transpiration cooled first wall and blanket concept assessment

  8. Respiration and transpiration characteristics of selected fresh fruits ...

    African Journals Online (AJOL)

    Respiration and transpiration characteristics of mushrooms, strawberries, broccoli and tomatoes were determined under different temperature, atmospheric and humidity conditions in order to get information for modified humidity atmosphere conception. The respiration rate was determined using a static method (scanning ...

  9. Effects of storage conditions on transpiration rate of pomegranate ...

    African Journals Online (AJOL)

    This study investigated the effects of temperature (5, 10, 15 and 22 °C) and relative humidity (RH) (76%, 86% and 96%) on the transpiration rate (TR) of pomegranate (Punica granatum L.) cv. Bhagwa fruit fractions, namely arils and aril-sac. Both temperature and RH had significant effects on the TR of fruit fractions. The TR ...

  10. Transpiration of glasshouse rose crops: evaluation of regression models

    NARCIS (Netherlands)

    Baas, R.; Rijssel, van E.

    2006-01-01

    Regression models of transpiration (T) based on global radiation inside the greenhouse (G), with or without energy input from heating pipes (Eh) and/or vapor pressure deficit (VPD) were parameterized. Therefore, data on T, G, temperatures from air, canopy and heating pipes, and VPD from both a

  11. ANNUAL AND DIURNAL CYCLES OF THE INVERSE RELATION BETWEEN PLANT TRANSPIRATION AND CARBON SEQUESTRATION

    Directory of Open Access Journals (Sweden)

    Hernán Alonso Moreno

    2008-07-01

    Full Text Available Understanding biogeochemical cycles and especially carbon budgets is clue to validate global change models in the present and near future. As a consequence, sinks and sources of carbon in the world are being studied. One of those sinks is the non-well known behavior of the planet vegetation which involves the processes of photosynthesis and respiration. Carbon sequestration rates are highly related to the transpiration through a molecular diffusion process occurring at the stomatal level which can be recorded by an eddy covariance micrometeorological station. This paper explores annual and diurnal cycles of latent heat (LE and CO2 net (FC fluxes over 6 different ecosystems. Based on the physics of the transpiration process, different time-scale analysis are performed, finding a near-linear relation between LE and CO2 net fluxes, which is stronger at the more vegetated areas. The North American monsoon season increases carbon up taking and LE-CO2 flux relation preserves at different time scales analysis (hours to days to months.El conocimiento de los ciclos biogeoquímicos y, en especial, de los balances de carbono es clave para la validación de los modelos de cambio global para el presente y el futuro cercano. Como consecuencia, en el mundo se estudian las fuentes y los sumideros de carbono. Uno de esos sumideros es la vegetación del planeta, que involucra los procesos de respiración y fotosíntesis y cuyo comportamiento se empieza a estudiar. Las tasas de captura del carbono están muy ligadas a la transpiración mediante un proceso de difusión molecular en los estomas, que puede registrarse por un sistema micrometeorológico de eddy covarianza. Este artículo explora los ciclos anuales y diurnos de los flujos netos de CO2 y calor latente de seis ecosistemas diferentes. Se desarrollan diversos análisis de escala temporal, basados en la física de la transpiración, y se halla una relación cuasilineal entre los flujos netos de calor

  12. Drought Response in Wheat: Key Genes and Regulatory Mechanisms Controlling Root System Architecture and Transpiration Efficiency

    Directory of Open Access Journals (Sweden)

    Manoj Kulkarni

    2017-12-01

    Full Text Available Abiotic stresses such as, drought, heat, salinity, and flooding threaten global food security. Crop genetic improvement with increased resilience to abiotic stresses is a critical component of crop breeding strategies. Wheat is an important cereal crop and a staple food source globally. Enhanced drought tolerance in wheat is critical for sustainable food production and global food security. Recent advances in drought tolerance research have uncovered many key genes and transcription regulators governing morpho-physiological traits. Genes controlling root architecture and stomatal development play an important role in soil moisture extraction and its retention, and therefore have been targets of molecular breeding strategies for improving drought tolerance. In this systematic review, we have summarized evidence of beneficial contributions of root and stomatal traits to plant adaptation to drought stress. Specifically, we discuss a few key genes such as, DRO1 in rice and ERECTA in Arabidopsis and rice that were identified to be the enhancers of drought tolerance via regulation of root traits and transpiration efficiency. Additionally, we highlight several transcription factor families, such as, ERF (ethylene response factors, DREB (dehydration responsive element binding, ZFP (zinc finger proteins, WRKY, and MYB that were identified to be both positive and negative regulators of drought responses in wheat, rice, maize, and/or Arabidopsis. The overall aim of this review is to provide an overview of candidate genes that have been identified as regulators of drought response in plants. The lack of a reference genome sequence for wheat and non-transgenic approaches for manipulation of gene functions in wheat in the past had impeded high-resolution interrogation of functional elements, including genes and QTLs, and their application in cultivar improvement. The recent developments in wheat genomics and reverse genetics, including the availability of a

  13. EFFECT OF SOIL WATER POTENTIAL ON TRANSPIRATION RATE IN CUCUMBER PLANTS

    OpenAIRE

    Cho, Tosio; Eguchi, Hiromi; Kuroda, Masaharu; Tanaka, Akira; Koutaki, Masahiro; Ng, Ah Lek; Matsui, Tsuyoshi

    1985-01-01

    In an attempt to examine the effect of soil water potential (pF) on transpiration rate, leaf temperature of cucumber plants was measured under various conditions of soil water potential, and transpiration rate was calculated from heat balance of the leaf. Transpiration rate decreased with reduction in soil water potential; transpiration rate dropped at soil water potentials lower than pF 3.0. This fact suggests that the reduction in soil water potential restricts water uptake in roots and cau...

  14. Biophysical control of whole tree transpiration under an urban environment in Northern China

    Science.gov (United States)

    Lixin Chen; Zhiqiang Zhang; Zhandong Li; Jianwu Tang; Peter Caldwell; et al

    2011-01-01

    Urban reforestation in China has led to increasing debate about the impact of urban trees and forests on water resources. Although transpiration is the largest water flux leaving terrestrial ecosystems, little is known regarding whole tree transpiration in urban environments. In this study, we quantified urban tree transpiration at various temporal scales and examined...

  15. Mechanistic assessment of hillslope transpiration controls of diel subsurface flow: a steady-state irrigation approach

    Science.gov (United States)

    H.R. Barnard; C.B. Graham; W.J. van Verseveld; J.R. Brooks; B.J. Bond; J.J. McDonnell

    2010-01-01

    Mechanistic assessment of how transpiration influences subsurface flow is necessary to advance understanding of catchment hydrology. We conducted a 24-day, steady-state irrigation experiment to quantify the relationships among soil moisture, transpiration and hillslope subsurface flow. Our objectives were to: (1) examine the time lag between maximum transpiration and...

  16. Transpiration in an oil palm landscape: effects of palm age

    Science.gov (United States)

    Röll, A.; Niu, F.; Meijide, A.; Hardanto, A.; Hendrayanto; Knohl, A.; Hölscher, D.

    2015-10-01

    Oil palm (Elaeis guineensis Jacq.) plantations cover large and continuously increasing areas of humid tropical lowlands. Landscapes dominated by oil palms usually consist of a mosaic of mono-cultural, homogeneous stands of varying age, which may be heterogeneous in their water use characteristics. However, studies on the water use characteristics of oil palms are still at an early stage and there is a lack of knowledge on how oil palm expansion will affect the major components of the hydrological cycle. To provide first insights into hydrological landscape-level consequences of oil palm cultivation, we derived transpiration rates of oil palms in stands of varying age, estimated the contribution of palm transpiration to evapotranspiration, and analyzed the influence of fluctuations in environmental variables on oil palm water use. We studied 15 two- to 25-year old stands in the lowlands of Jambi, Indonesia. A sap flux technique with an oil palm specific calibration and sampling scheme was used to derive leaf-, palm- and stand-level water use rates in all stands under comparable environmental conditions. Additionally, in a two- and a 12-year old stand, eddy covariance measurements were conducted to derive evapotranspiration rates. Water use rates per leaf and palm increased 5-fold from an age of 2 years to a stand age of approx. 10 years and then remained relatively constant. A similar trend was visible, but less pronounced, for estimated stand transpiration rates of oil palms; they varied 12-fold, from 0.2 mm day-1 in a 2-year old to 2.5 mm day-1 in a 12-year old stand, showing particularly high variability in transpiration rates among medium-aged stands. Comparing sap flux and eddy-covariance derived water fluxes suggests that transpiration contributed 8 % to evapotranspiration in the 2-year old stand and 53 % in the 12-year old stand, indicating variable and substantial additional sources of evaporation, e.g., from the soil, the ground vegetation and from trunk

  17. Analysis of Stomatal Patterning in Selected Mutants of MAPK Pathways

    KAUST Repository

    Felemban, Abrar

    2016-05-01

    Stomata are cellular valves in plants that play an essential role in the regulation of gas exchange and are distributed in the epidermis of aerial organs. In Arabidopsis thaliana, stomatal production and development are coordinated by the mitogen-activated protein kinase (MAPK) signalling pathway, which modulates a variety of other processes, including cell proliferation, regulation of cytokinesis, programed cell death, and response to abiotic and biotic stress. The environment also plays a role in stomatal development, by influencing the frequency at which stomata develop in leaves. This thesis presents an analysis of stomatal development in Arabidopsis mutants in two MAPK pathways: MEKK1-MKK1/MKK2-MPK4, and MAP3K17/18-MKK3. Obtained results demonstrate the effect of stress conditions on stomatal development and specify the involvement of analysed MAPK in stomatal patterning. First, both analysed pathways modulate stomatal patterning in Arabidopsis cotyledons. Second, plant growth-promoting bacteria tested enhance stomatal density and affect guard cell morphology. Third, the sucrose or mannitol treatment increases defects in stomatal patterning. Finally, salt stress or high temperature can suppress stomatal defects in mutants of the MEKK1-MKK1/MKK2-MPK4 pathway.

  18. Plant water potential improves prediction of empirical stomatal models.

    Directory of Open Access Journals (Sweden)

    William R L Anderegg

    Full Text Available Climate change is expected to lead to increases in drought frequency and severity, with deleterious effects on many ecosystems. Stomatal responses to changing environmental conditions form the backbone of all ecosystem models, but are based on empirical relationships and are not well-tested during drought conditions. Here, we use a dataset of 34 woody plant species spanning global forest biomes to examine the effect of leaf water potential on stomatal conductance and test the predictive accuracy of three major stomatal models and a recently proposed model. We find that current leaf-level empirical models have consistent biases of over-prediction of stomatal conductance during dry conditions, particularly at low soil water potentials. Furthermore, the recently proposed stomatal conductance model yields increases in predictive capability compared to current models, and with particular improvement during drought conditions. Our results reveal that including stomatal sensitivity to declining water potential and consequent impairment of plant water transport will improve predictions during drought conditions and show that many biomes contain a diversity of plant stomatal strategies that range from risky to conservative stomatal regulation during water stress. Such improvements in stomatal simulation are greatly needed to help unravel and predict the response of ecosystems to future climate extremes.

  19. Transpiration and CO2 fluxes of a pine forest: modelling the undergrowth effect

    Directory of Open Access Journals (Sweden)

    V. Rivalland

    2005-02-01

    Full Text Available A modelling study is performed in order to quantify the relative effect of allowing for the physiological properties of an undergrowth grass sward on total canopy water and carbon fluxes of the Le-Bray forest (Les-Landes, South-western France. The Le-Bray forest consists of maritime pine and an herbaceous undergrowth (purple moor-grass, which is characterised by a low stomatal control of transpiration, in contrast to maritime pine. A CO2-responsive land surface model is used that includes responses of woody and herbaceous species to water stress. An attempt is made to represent the properties of the undergrowth vegetation in the land surface model Interactions between Soil, Biosphere, and Atmosphere, CO2-responsive, ISBA-A-gs. The new adjustment allows for a fairly different environmental response between the forest canopy and the understory in a simple manner. The model's simulations are compared with long term (1997 and 1998 micro-meteorological measurements over the Le-Bray site. The fluxes of energy, water and CO2, are simulated with and without the improved representation of the undergrowth vegetation, and the two simulations are compared with the observations. Accounting for the undergrowth permits one to improve the model's scores. A simple sensitivity experiment shows the behaviour of the model in response to climate change conditions, and the understory effect on the water balance and carbon storage of the forest. Accounting for the distinct characteristics of the undergrowth has a substantial and positive effect on the model accuracy and leads to a different response to climate change scenarios.

  20. Origins and evolution of stomatal development

    OpenAIRE

    Chater, C.; Caine, R.S.; Fleming, A.J.; Gray, J.E.

    2017-01-01

    The fossil record suggests stomata-like pores were present on the surfaces of land plants over 400 million years ago.\\ud Whether stomata arose once or whether they arose independently across newly evolving land plant lineages has long been\\ud a matter of debate. In Arabidopsis, a genetic toolbox has been identified that tightly controls stomatal development and\\ud patterning. This includes the basic helix-loop-helix (bHLH) transcription factors SPEECHLESS (SPCH), MUTE, FAMA, and\\ud ICE/SCREAM...

  1. Mistletoe infection alters the transpiration flow path and suppresses water regulation of host trees during extreme events

    Science.gov (United States)

    Griebel, A.; Maier, C.; Barton, C. V.; Metzen, D.; Renchon, A.; Boer, M. M.; Pendall, E.

    2017-12-01

    Mistletoe is a globally distributed group of parasitic plants that infiltrates the vascular tissue of its host trees to acquire water, carbon and nutrients, making it a leading agent of biotic disturbance. Many mistletoes occur in water-limited ecosystems, thus mistletoe infection in combination with increased climatic stress may exacerbate water stress and potentially accelerate mortality rates of infected trees during extreme events. This is an emerging problem in Australia, as mistletoe distribution is increasing and clear links between mistletoe infection and mortality have been established. However, direct observations about how mistletoes alter host physiological processes during extreme events are rare, which impedes our understanding of mechanisms underlying increased tree mortality rates. We addressed this gap by continuously monitoring stem and branch sap flow and a range of leaf traits of infected and uninfected trees of two co-occurring eucalypt species during a severe heatwave in south-eastern Australia. We demonstrate that mistletoes' leaf water potentials were maintained 30% lower than hosts' to redirect the trees' transpiration flow path towards mistletoe leaves. Eucalypt leaves reduced water loss through stomatal regulation when atmospheric dryness exceeded 2 kPa, but the magnitude of stomatal regulation in non-infected eucalypts differed by species (between 40-80%). Remarkably, when infected, sap flow rates of stems and branches of both eucalypt species remained unregulated even under extreme atmospheric dryness (>8 kPa). Our observations indicate that excessive water use of mistletoes likely increases xylem cavitation rates in hosts during prolonged droughts and supports that hydraulic failure contributes to increased mortality of infected trees. Hence, in order to accurately model the contribution of biotic disturbances to tree mortality under a changing climate, it will be crucial to increase our process-based understanding of the interaction

  2. A banana NAC transcription factor (MusaSNAC1) impart drought tolerance by modulating stomatal closure and H2O2 content.

    Science.gov (United States)

    Negi, Sanjana; Tak, Himanshu; Ganapathi, T R

    2018-03-01

    MusaSNAC1 function in H 2 O 2 mediated stomatal closure and promote drought tolerance by directly binding to CGT[A/G] motif in regulatory region of multiple stress-related genes. Drought is a abiotic stress-condition, causing reduced plant growth and diminished crop yield. Guard cells of the stomata control photosynthesis and transpiration by regulating CO 2 exchange and water loss, thus affecting growth and crop yield. Roles of NAC (NAM, ATAF1/2 and CUC2) protein in regulation of stress-conditions has been well documented however, their control over stomatal aperture is largely unknown. In this study we report a banana NAC protein, MusaSNAC1 which induced stomatal closure by elevating H 2 O 2 content in guard cells during drought stress. Overexpression of MusaSNAC1 in banana resulted in higher number of stomata closure causing reduced water loss and thus elevated drought-tolerance. During drought, expression of GUS (β-glucuronidase) under P MusaSNAC1 was remarkably elevated in guard cells of stomata which correlated with its function as a transcription factor regulating stomatal aperture closing. MusaSNAC1 is a transcriptional activator belonging to SNAC subgroup and its 5'-upstream region contain multiple Dof1 elements as well as stress-associated cis-elements. Moreover, MusaSNAC1 also regulate multiple stress-related genes by binding to core site of NAC-proteins CGT[A/G] in their 5'-upstream region. Results indicated an interesting mechanism of drought tolerance through stomatal closure by H 2 O 2 generation in guard cells, regulated by a NAC-protein in banana.

  3. Further insights into the components of resistance to Ophiostoma novo-ulmi in Ulmus minor: hydraulic conductance, stomatal sensitivity and bark dehydration.

    Science.gov (United States)

    Pita, Pilar; Rodríguez-Calcerrada, Jesús; Medel, David; Gil, Luis

    2018-02-01

    Dutch elm disease (DED) is a vascular disease that has killed over 1 billion elm trees. The pathogen spreads throughout the xylem network triggering vessel blockage, which results in water stress, tissue dehydration and extensive leaf wilting in susceptible genotypes. We investigated the differences between four Ulmus minor Mill. clones of contrasting susceptibility to Ophiostoma novo-ulmi Brasier regarding morphological, anatomical and physiological traits affecting water transport, in order to gain a better understanding of the mechanisms underlying DED susceptibility. We analyzed the differential response to water shortage and increased air vapor pressure deficit (VPD) to investigate whether resistance to water stress might be related to DED tolerance. Sixteen plants per clone, aged 2 years, were grown inside a greenhouse under differential watering. Stomatal conductance was measured under ambient and increased VPD. Growth, bark water content and stem hydraulic and anatomical parameters were measured 22 days after starting differential watering. Vessel lumen area, lumen fraction and hydraulic conductance were highest in susceptible clones. Stomatal conductance was lowest under low VPD and decreased faster under increased VPD in resistant clones. We found a negative relationship between the decrease in stomatal conductance at increased VPD and specific hydraulic conductance, revealing a narrower hydraulic margin for sustaining transpiration in resistant clones. The effect of water shortage was greater on radial stem growth than on leaf area, which could be explained through an extensive use of capacitance water to buffer xylem water potential. Water shortage reduced stomatal conductance and vessel lumen area. Bark water content under conditions of water shortage only decreased in susceptible clones. Higher hydraulic constraints to sap flow in resistant clones may determine higher stomatal sensitivity to VPD and so contribute to DED resistance by limiting pathogen

  4. Revisiting the contribution of transpiration to global terrestrial evapotranspiration

    OpenAIRE

    Wei, Zhongwang; Yoshimura, Kei; Wang, Lixin; Gonzalez Miralles, Diego; Jasechko, Scott; Lee, Xuhui

    2017-01-01

    Even though knowing the contributions of transpiration (T), soil and open water evaporation (E), and interception (I) to terrestrial evapotranspiration (ET = T + E + I) is crucial for understanding the hydrological cycle and its connection to ecological processes, the fraction of T is unattainable by traditional measurement techniques over large scales. Previously reported global mean T/(E + T + I) from multiple independent sources, including satellite-based estimations, reanalysis, land surf...

  5. Seasonal variability of the parameters of the Ball-Berry model of stomatal conductance in maize (Zea mays L.) and sunflower (Helianthus annuus L.) under well-watered and water-stressed conditions.

    Science.gov (United States)

    Miner, Grace L; Bauerle, William L

    2017-09-01

    The Ball-Berry (BB) model of stomatal conductance (g s ) is frequently coupled with a model of assimilation to estimate water and carbon exchanges in plant canopies. The empirical slope (m) and 'residual' g s (g 0 ) parameters of the BB model influence transpiration estimates, but the time-intensive nature of measurement limits species-specific data on seasonal and stress responses. We measured m and g 0 seasonally and under different water availability for maize and sunflower. The statistical method used to estimate parameters impacted values nominally when inter-plant variability was low, but had substantial impact with larger inter-plant variability. Values for maize (m = 4.53 ± 0.65; g 0  = 0.017 ± 0.016 mol m -2 s -1 ) were 40% higher than other published values. In maize, we found no seasonal changes in m or g 0 , supporting the use of constant seasonal values, but water stress reduced both parameters. In sunflower, inter-plant variability of m and g 0 was large (m = 8.84 ± 3.77; g 0  = 0.354 ± 0.226 mol m -2 s -1 ), presenting a challenge to clear interpretation of seasonal and water stress responses - m values were stable seasonally, even as g 0 values trended downward, and m values trended downward with water stress while g 0 values declined substantially. © 2017 John Wiley & Sons Ltd.

  6. A method to determine plant water source using transpired water

    Science.gov (United States)

    Menchaca, L. B.; Smith, B. M.; Connolly, J.; Conrad, M.; Emmett, B.

    2007-04-01

    A method to determine the stable isotope ratio of a plant's water source using the plant's transpired water is proposed as an alternative to standard xylem extraction methods. The method consists of periodically sampling transpired waters from shoots or leaves enclosed in sealed, transparent bags which create a saturated environment, preclude further evaporation and allow the progressive mixing of evaporated transpired water and un-evaporated xylem water. The method was applied on trees and shrubs coexisting in a non-irrigated area where stable isotope ratios of local environmental waters are well characterized. The results show Eucalyptus globulus (tree) and Genista monspessulana (shrub) using water sources of different isotopic ratios congruent with groundwater and soil water respectively. In addition, tritium concentrations indicate that pine trees (Pinus sylvestris) switch water source from soil water in the winter to groundwater in the summer. The method proposed is particularly useful in remote or protected areas and in large scale studies related to water management, environmental compliance and surveillance, because it eliminates the need for destructive sampling and greatly reduces costs associated with laboratory extraction of xylem waters from plant tissues for isotopic analyses.

  7. Mechanisms of stomatal development: an evolutionary view.

    Science.gov (United States)

    Vatén, Anne; Bergmann, Dominique C

    2012-07-06

    Plant development has a significant postembryonic phase that is guided heavily by interactions between the plant and the outside environment. This interplay is particularly evident in the development, pattern and function of stomata, epidermal pores on the aerial surfaces of land plants. Stomata have been found in fossils dating from more than 400 million years ago. Strikingly, the morphology of the individual stomatal complex is largely unchanged, but the sizes, numbers and arrangements of stomata and their surrounding cells have diversified tremendously. In many plants, stomata arise from specialized and transient stem-cell like compartments on the leaf. Studies in the flowering plant Arabidopsis thaliana have established a basic molecular framework for the acquisition of cell fate and generation of cell polarity in these compartments, as well as describing some of the key signals and receptors required to produce stomata in organized patterns and in environmentally optimized numbers. Here we present parallel analyses of stomatal developmental pathways at morphological and molecular levels and describe the innovations made by particular clades of plants.

  8. Mechanisms of stomatal development: an evolutionary view

    Directory of Open Access Journals (Sweden)

    Vatén Anne

    2012-07-01

    Full Text Available Abstract Plant development has a significant postembryonic phase that is guided heavily by interactions between the plant and the outside environment. This interplay is particularly evident in the development, pattern and function of stomata, epidermal pores on the aerial surfaces of land plants. Stomata have been found in fossils dating from more than 400 million years ago. Strikingly, the morphology of the individual stomatal complex is largely unchanged, but the sizes, numbers and arrangements of stomata and their surrounding cells have diversified tremendously. In many plants, stomata arise from specialized and transient stem-cell like compartments on the leaf. Studies in the flowering plant Arabidopsis thaliana have established a basic molecular framework for the acquisition of cell fate and generation of cell polarity in these compartments, as well as describing some of the key signals and receptors required to produce stomata in organized patterns and in environmentally optimized numbers. Here we present parallel analyses of stomatal developmental pathways at morphological and molecular levels and describe the innovations made by particular clades of plants.

  9. Relationship of leaf oxygen and carbon isotopic composition with transpiration efficiency in the C4 grasses Setaria viridis and Setaria italica.

    Science.gov (United States)

    Ellsworth, Patrick Z; Ellsworth, Patrícia V; Cousins, Asaph B

    2017-06-15

    Leaf carbon and oxygen isotope ratios can potentially provide a time-integrated proxy for stomatal conductance (gs) and transpiration rate (E), and can be used to estimate transpiration efficiency (TE). In this study, we found significant relationships of bulk leaf carbon isotopic signature (δ13CBL) and bulk leaf oxygen enrichment above source water (Δ18OBL) with gas exchange and TE in the model C4 grasses Setaria viridis and S. italica. Leaf δ13C had strong relationships with E, gs, water use, biomass, and TE. Additionally, the consistent difference in δ13CBL between well-watered and water-limited plants suggests that δ13CBL is effective in separating C4 plants with different availability of water. Alternatively, the use of Δ18OBL as a proxy for E and TE in S. viridis and S. italica was problematic. First, the oxygen isotopic composition of source water, used to calculate leaf water enrichment (Δ18OLW), was variable with time and differed across water treatments. Second, water limitations changed leaf size and masked the relationship of Δ18OLW and Δ18OBL with E. Therefore, the data collected here suggest that δ13CBL but not Δ18OBL may be an effective proxy for TE in C4 grasses. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  10. Water, heat, and airborne pollutants effects on transpiration of urban trees

    International Nuclear Information System (INIS)

    Wang Hua; Ouyang Zhiyun; Chen Weiping; Wang Xiaoke; Zheng Hua; Ren Yufen

    2011-01-01

    Transpiration rates of six urban tree species in Beijing evaluated by thermal dissipation method for one year were correlated to environmental variables in heat, water, and pollutant groups. To sort out colinearity of the explanatory variables, their individual and joint contributions to variance of tree transpiration were determined by the variation and hierarchical partitioning methods. Majority of the variance in transpiration rates was associated with joint effects of variables in heat and water groups and variance due to individual effects of explanatory group were in comparison small. Atmospheric pollutants exerted only minor effects on tree transpiration. Daily transpiration rate was most affected by air temperature, soil temperature, total radiation, vapor pressure deficit, and ozone. Relative humidity would replace soil temperature when factors influencing hourly transpiration rate was considered. - Highlights: → Heat, water, pollutants effect on transpiration was evaluated by partitioning method. → Urban tree transpiration was mainly affected by combined effects of these variables. → The heat and water variables affected transpiration of urban trees. → The urban air pollution merely acts as an antagonistic factor. - Heat and water related environmental variables affected transpiration of urban trees and ozone was an added yet minor stress factor.

  11. Increase in leaf temperature opens stomata and decouples net photosynthesis from stomatal conductance in Pinus taeda and Populus deltoides x nigra.

    Science.gov (United States)

    Urban, Josef; Ingwers, Miles W; McGuire, Mary Anne; Teskey, Robert O

    2017-03-01

    The effect of temperature on stomatal conductance (gs) and corresponding gas exchange parameters was studied in two tree species with contrasting leaf anatomy and ecophysiology-a broadleaf angiosperm, Populus deltoides x nigra (poplar), and a needle-leaf gymnosperm, Pinus taeda (loblolly pine). Experiments were conducted in growth chambers across a leaf temperature range of 19-48°C. Manipulations of temperature were done in well-watered and drought soil conditions and under ambient (400 ppm) and elevated (800 ppm) air CO2 concentrations. Increases in leaf temperature caused stomatal opening at both ambient and elevated [CO2]. The gs increased by 42% in poplar and by 40% in loblolly pine when leaf temperature increased from 30°C to 40°C at a vapour pressure difference of 1 kPa. Stomatal limitation to photosynthesis decreased in elevated temperature in loblolly pine but not in poplar. The ratio of net photosynthesis to gs depended on leaf temperature, especially at high temperatures. Evaporative cooling of transpiring leaves resulted in reductions in leaf temperature up to 9°C in well-watered poplar but only 1°C in drought-stressed poplar and in loblolly pine. As global mean temperatures rise and temperature extremes become more frequent and severe, understanding the effect of temperature on gs, and modelling that relationship, will become increasingly important. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  12. Origins and Evolution of Stomatal Development1[OPEN

    Science.gov (United States)

    2017-01-01

    The fossil record suggests stomata-like pores were present on the surfaces of land plants over 400 million years ago. Whether stomata arose once or whether they arose independently across newly evolving land plant lineages has long been a matter of debate. In Arabidopsis, a genetic toolbox has been identified that tightly controls stomatal development and patterning. This includes the basic helix-loop-helix (bHLH) transcription factors SPEECHLESS (SPCH), MUTE, FAMA, and ICE/SCREAMs (SCRMs), which promote stomatal formation. These factors are regulated via a signaling cascade, which includes mobile EPIDERMAL PATTERNING FACTOR (EPF) peptides to enforce stomatal spacing. Mosses and hornworts, the most ancient extant lineages to possess stomata, possess orthologs of these Arabidopsis (Arabidopsis thaliana) stomatal toolbox genes, and manipulation in the model bryophyte Physcomitrella patens has shown that the bHLH and EPF components are also required for moss stomatal development and patterning. This supports an ancient and tightly conserved genetic origin of stomata. Here, we review recent discoveries and, by interrogating newly available plant genomes, we advance the story of stomatal development and patterning across land plant evolution. Furthermore, we identify potential orthologs of the key toolbox genes in a hornwort, further supporting a single ancient genetic origin of stomata in the ancestor to all stomatous land plants. PMID:28356502

  13. Flexible Transpiration Cooled Thermal Protection System for Inflatable Atmospheric Capture and Entry Systems, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Andrews Space, Inc. proposes an innovative transpiration cooled aerobrake TPS design that is thermally protective, structurally flexible, and lightweight. This...

  14. Flexible Transpiration Cooled Thermal Protection System for Inflatable Atmospheric Capture and Entry Systems, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Andrews Space, Inc. proposes an innovative transpiration cooled aerobrake TPS design that is thermally protective, structurally flexible, and lightweight. This...

  15. Two-Site Comparison of Transpiration by Larrea Tridentata

    Science.gov (United States)

    Cavanaugh, M. L.; Kurc, S. A.; Scott, R. L.; Bryant, R. B.

    2008-12-01

    As a result of landscape changes within the desert southwestern U.S. such as increased grazing, reduced wildfire frequency, and changes in atmospheric conditions, the native creosotebush (Larrea tridentata) has encroached upon historically grass-dominated ecosystems, expanding in range and land cover density. To understand how creosotebush influences the water budget of ecosystems, heat balance sap flow sensors were employed on creosotebush stems at both the Santa Rita Experimental Range (SRER) and Walnut Gulch Experimental Watershed (WGEW). Additionally, both sites are equipped with eddy covariance towers, associated micrometeorological measurements, and profiles of water content reflectometers for soil moisture. The differences found between the two sites, including soil type and precipitation regime, are the basis of the following hypotheses. Firstly, we hypothesize that we will not see transpiration (T) responses following storms less than 5 mm at both sites. Secondly, we hypothesize that at both sites we will see a lagged response of T to large precipitation events, with evaporation being the dominate component in the partitioning of evapotranspiration (ET) for the first two days. Thirdly, we hypothesize that the ratio of plant transpiration to total evapotranspiration (T/ET) will be less at SRER due to the larger amount of bare soil exposed at this site. In this study, we show data from one summer at both sites and show how these relate to different precipitation events and soil moisture reservoirs.

  16. Modeling productivity and transpiration of Pinus radiata: climatic effects.

    Science.gov (United States)

    Sheriff, D. W.; Mattay, J. P.; McMurtrie, R. E.

    1996-01-01

    Climatic effects on annual net carbon gain, stem biomass and annual transpiration were simulated for Pinus radiata D. Don at Canberra and Mt. Gambier. Simulations were conducted with an existing process-based forest growth model (BIOMASS, Model 1) and with a modified version of the BIOMASS model (Model 2) in which response functions for carbon assimilation and leaf conductance were replaced with those derived from field gas exchange data collected at Mt. Gambier. Simulated carbon gain was compared with a published report stating that mean annual stem volume increment (MAI) at Mt. Gambier was 1.8 times greater than at Canberra and that the difference could be the result solely of differences in climate. Regional differences in climate resulted in a 20% greater simulated annual transpiration at Canberra than at Mt. Gambier but only small differences in simulated productivity, indicating that climatic differences did not account for the reported differences in productivity. With Model 1, simulated annual net carbon gain and annual increase in stem biomass were greater at Canberra than at Mt. Gambier, whereas Model 2 indicated a similar annual net carbon gain and annual stem biomass increase in both regions.

  17. Residual deposits (residual soil)

    International Nuclear Information System (INIS)

    Khasanov, A.Kh.

    1988-01-01

    Residual soil deposits is accumulation of new formate ore minerals on the earth surface, arise as a result of chemical decomposition of rocks. As is well known, at the hyper genes zone under the influence of different factors (water, carbonic acid, organic acids, oxygen, microorganism activity) passes chemical weathering of rocks. Residual soil deposits forming depends from complex of geologic and climatic factors and also from composition and physical and chemical properties of initial rocks

  18. Transcription co-activator Arabidopsis ANGUSTIFOLIA3 (AN3) regulates water-use efficiency and drought tolerance by modulating stomatal density and improving root architecture by the transrepression of YODA (YDA).

    Science.gov (United States)

    Meng, Lai-Sheng; Yao, Shun-Qiao

    2015-09-01

    One goal of modern agriculture is the improvement of plant drought tolerance and water-use efficiency (WUE). Although stomatal density has been linked to WUE, the causal molecular mechanisms and engineered alternations of this relationship are not yet fully understood. Moreover, YODA (YDA), which is a MAPKK kinase gene, negatively regulates stomatal development. BR-INSENSITIVE 2 interacts with phosphorylates and inhibits YDA. However, whether YDA is modulated in the transcriptional level is still unclear. Plants lacking ANGUSTIFOLIA3 (AN3) activity have high drought stress tolerance because of low stomatal densities and improved root architecture. Such plants also exhibit enhanced WUE through declining transpiration without a demonstrable reduction in biomass accumulation. AN3 negatively regulated YDA expression at the transcriptional level by target-gene analysis. Chromatin immunoprecipitation analysis indicated that AN3 was associated with a region of the YDA promoter in vivo. YDA mutation significantly decreased the stomatal density and root length of an3 mutant, thus proving the participation of YDA in an3 drought tolerance and WUE enhancement. These components form an AN3-YDA complex, which allows the integration of water deficit stress signalling into the production or spacing of stomata and cell proliferation, thus leading to drought tolerance and enhanced WUE. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  19. Testing a hydraulic trait based model of stomatal control: results from a controlled drought experiment on aspen (Populus tremuloides, Michx.) and ponderosa pine (Pinus ponderosa, Douglas)

    Science.gov (United States)

    Love, D. M.; Venturas, M.; Sperry, J.; Wang, Y.; Anderegg, W.

    2017-12-01

    Modeling approaches for tree stomatal control often rely on empirical fitting to provide accurate estimates of whole tree transpiration (E) and assimilation (A), which are limited in their predictive power by the data envelope used to calibrate model parameters. Optimization based models hold promise as a means to predict stomatal behavior under novel climate conditions. We designed an experiment to test a hydraulic trait based optimization model, which predicts stomatal conductance from a gain/risk approach. Optimal stomatal conductance is expected to maximize the potential carbon gain by photosynthesis, and minimize the risk to hydraulic transport imposed by cavitation. The modeled risk to the hydraulic network is assessed from cavitation vulnerability curves, a commonly measured physiological trait in woody plant species. Over a growing season garden grown plots of aspen (Populus tremuloides, Michx.) and ponderosa pine (Pinus ponderosa, Douglas) were subjected to three distinct drought treatments (moderate, severe, severe with rehydration) relative to a control plot to test model predictions. Model outputs of predicted E, A, and xylem pressure can be directly compared to both continuous data (whole tree sapflux, soil moisture) and point measurements (leaf level E, A, xylem pressure). The model also predicts levels of whole tree hydraulic impairment expected to increase mortality risk. This threshold is used to estimate survivorship in the drought treatment plots. The model can be run at two scales, either entirely from climate (meteorological inputs, irrigation) or using the physiological measurements as a starting point. These data will be used to study model performance and utility, and aid in developing the model for larger scale applications.

  20. Soil phosphorous and endogenous rhythms exert a larger impact than CO2 or temperature on nocturnal stomatal conductance in Eucalyptus tereticornis.

    Science.gov (United States)

    de Dios, Víctor Resco; Turnbull, Matthew H; Barbour, Margaret M; Ontedhu, Josephine; Ghannoum, Oula; Tissue, David T

    2013-11-01

    High nocturnal transpiration rates (5-15% of total water loss in terrestrial plants) may be adaptive under limited fertility, by increasing nutrient uptake or transport via transpiration-induced mass flow, but the response of stomata in the dark to environmental variables is poorly understood. Here we tested the impact of soil phosphorous (P) concentration, atmospheric CO2 concentration and air temperature on stomatal conductance (gs) during early and late periods in the night, as well as at midday in naturally, sun-lit glasshouse-grown Eucalyptus tereticornis Sm. seedlings. Soil P was the main driver of nocturnal gs, which was consistently higher in low soil P (37.3-79.9 mmol m(-2) s(-1)) than in high soil P (17.7-49.3 mmol m(-2)(-1)). Elevated temperature had only a marginal (P = 0.07) effect on gs early in the night (gs decreased from 34.7 to 25.8 mmol m(-2) s(-1) with an increase in temperature of 4 °C). The effect of CO2 depended on its interaction with temperature. Stomatal conductance responses to soil P were apparently driven by indirect effects of soil P on plant anatomy, since gs was significantly and negatively correlated with wood density. However, the relationship of gs with environmental factors became weaker late in the night, relative to early in the night, likely due to apparent endogenous processes; gs late in the night was two times larger than gs observed early in the night. Time-dependent controls over nocturnal gs suggest that daytime stomatal models may not apply during the night, and that different types of regulation may occur even within a single night. We conclude that the enhancement of nocturnal gs under low soil P availability is unlikely to be adaptive in our species because of the relatively small amount of transpiration-induced mass flow that can be achieved through rates of nocturnal water loss (3-6% of daytime mass flow).

  1. Fruit calcium accumulation coupled and uncoupled from its transpiration in kiwifruit.

    Science.gov (United States)

    Montanaro, Giuseppe; Dichio, Bartolomeo; Lang, Alexander; Mininni, Alba N; Xiloyannis, Cristos

    2015-06-01

    Accumulation of Ca in several fleshy fruit is often supposed to depend, among others, by climatic variables driving fruit transpiration. This study tests the whole causal chain hypothesis: VPD → fruit transpiration → Ca accumulation. Also there are evidences that relationship between fruit transpiration and Ca content is not always clear, hence the hypothesis that low VPD reduces the fraction of xylemic water destined to transpiration was tested by examining the water budget of fruit. Attached fruits of Actinidia deliciosa were subjected to Low (L) and High (H) VPD. Their transpiration was measured from early after fruit-set to day 157 after full bloom (DAFB). Fruits were picked at 70, 130 and 157 DAFB for Ca and K determinations and for water budget analysis. Cumulative transpired water was ∼ 70 g and ∼ 16 g H2O f(-1) in HVPD and LVPD, respectively. Calcium accumulated linearly (R(2) = 0.71) with cumulative transpiration when VPD was high, while correlation was weaker (R(2) = 0.24) under LVPD. Under low VPD the fraction of xylem stream destined to transpiration declined to 40-50%. Results suggest that Ca accumulation is coupled to cumulative transpiration under high VPD because under that condition cumulative transpiration equals xylem stream (which carry the nutrient). At LVPD, Ca gain by fruit is uncoupled from transpiration because ∼ 60% of the xylemic water is needed to sustain fruit growth. Results will apply to most fruits (apples, tomatoes, capsicum, grapes etc.) since most suffer Ca deficiency disorders and grow in changing environments with variable VPD, also they could be supportive for the implementation of fruit quality models accounting also for mineral compositions and for a reinterpretation of certain field practices aimed at naturally improve fruit Ca content. Copyright © 2015 Elsevier GmbH. All rights reserved.

  2. Recurrent aphthous stomatitis: a case report

    Directory of Open Access Journals (Sweden)

    Xiomara Serpa-Romero

    2016-07-01

    Full Text Available Recurrent aphthosus stomatitis is an alteration of the oral mucosa in some cases associated with depression of the immune system that affects the tissue response at the level of the epithelium, triggering repetitive clinical picture of small and medium ulcers (3-5 mm which necrotic presented erythematous background and lasting no more than 15 days. The picture becomes recurrent, symptomatic, compromising the health of the patient who consults again with the same characteristics in oral cavity. The literature associates the process with hormonal changes, trauma, prolonged intake of medications, and stress. A case of female patient 53, who attends the service of dentistry to present multiple oral thrush that hard to swallow, drooling and feverish marked presents in Santa Marta, at the Center for Implantology and Oral Rehabilitation. According to the interrogation and clinical examination it is associated with a reactive inflammatory process caused by the intake of drugs to treat infectious or viral process, which is given the presumptive diagnosis of erythema drug. Any medication intake was suspended and additional tests are ordered antinuclear antibodies

  3. [Stomatitis from dentures: etiopathological and therapeutic considerations].

    Science.gov (United States)

    Tejerina Lobo, J M; Bagan Sebastián, J V; Ramón Muñiz, J

    1989-05-01

    Infection of the oral mucous membrane is frequent in patients with removable prostheses, either totally of partially, and particularly when the prostheses is palatal. The principal etiological factor causing the infection is accepted to be "Candidas" aided by the presence of plaque bacteria (in patients with poor oral hygiene care), and a poor fit of the prostheses to the soft tissues. Treatment of the infection must proceed in the following order: a) use of effective medication against oral fungus such as Nystatin or Ketoconazole. b) Meticulous oral hygiene care in the mucous membrane as well as in the prostheses, but using the prostheses as little as possible during the treatment period. c) A total cure of the infection (denture stomatitis) before proceeding to the next phase of the treatment. d) Determination of the adjustment and occlusion of the prostheses in order to determine those areas of the prostheses which need to be refilled because of maladjustment of the prostheses to the soft tissues of the patient.

  4. The acclimation of Tilia cordata stomatal opening in response to light, and stomatal anatomy to vegetational shade and its components.

    Science.gov (United States)

    Aasamaa, Krõõt; Aphalo, Pedro José

    2017-02-01

    Stomatal anatomical traits and rapid responses to several components of visible light were measured in Tilia cordata Mill. seedlings grown in an open, fully sunlit field (C-set), or under different kinds of shade. The main questions were: (i) stomatal responses to which visible light spectrum regions are modified by growth-environment shade and (ii) which separate component of vegetational shade is most effective in eliciting the acclimation effects of the full vegetational shade. We found that stomatal opening in response to red or green light did not differ between the plants grown in the different environments. Stomatal response to blue light was increased (in comparison with that of C-set) in the leaves grown in full vegetational shade (IABW-set), in attenuated UVAB irradiance (AB-set) or in decreased light intensity (neutral shade) plus attenuated UVAB irradiance (IAB-set). In all sets, the addition of green light-two or four times stronger-into induction light barely changed the rate of the blue-light-stimulated stomatal opening. In the AB-set, stomatal response to blue light equalled the strong IABW-set response. In attenuated UVB-grown leaves, stomatal response fell midway between IABW- and C-set results. Blue light response by neutral shade-grown leaves did not differ from that of the C-set, and the response by the IAB-set did not differ from that of the AB-set. Stomatal size was not modified by growth environments. Stomatal density and index were remarkably decreased only in the IABW- and IAB-sets. It was concluded that differences in white light responses between T. cordata leaves grown in different light environments are caused only by their different blue light response. Differences in stomatal sensitivity are not dependent on altered stomatal anatomy. Attenuated UVAB irradiance is the most efficient component of vegetational shade in stimulating acclimation of stomata, whereas decreased light intensity plays a minor role. © The Author 2016. Published

  5. Measuring whole-plant transpiration gravimetrically: a scalable automated system built from components

    Science.gov (United States)

    Damian Cirelli; Victor J. Lieffers; Melvin T. Tyree

    2012-01-01

    Measuring whole-plant transpiration is highly relevant considering the increasing interest in understanding and improving plant water use at the whole-plant level. We present an original software package (Amalthea) and a design to create a system for measuring transpiration using laboratory balances based on the readily available commodity hardware. The system is...

  6. The sensitivity of regional transpiration to land-surface characteristics: significance of feedback.

    NARCIS (Netherlands)

    Jacobs, C.M.J.; Bruin, de H.A.R.

    1992-01-01

    Several authors have determined the sensitivity of transpiration to different environmental parameters using the Penman-Monteith equation. In their studies the interaction between transpiration and, for example, the humidity of the air is ignored: the feedback with the planetary boundary layer (PBL)

  7. The shape of the transpiration reduction function under plant water stress

    NARCIS (Netherlands)

    Metselaar, K.; Jong van Lier, de Q.

    2007-01-01

    Assuming transpiration to be reduced after a critical pressure head (usually chosen as −1.5 MPa or −150 m) at the root surface has been reached, transpiration rates in this so-called falling-rate phase were analyzed numerically for soils described by the van Genuchten–Mualem equations (numerical

  8. A prototype photovoltaic/thermal system integrated with transpired collector

    Energy Technology Data Exchange (ETDEWEB)

    Athienitis, Andreas K.; Bambara, James; O' Neill, Brendan; Faille, Jonathan [Dept. of Building, Civil and Environmental Engineering, Concordia University, 1455 Maisonneuve W., Montreal, Quebec (Canada)

    2011-01-15

    Building-integrated photovoltaic/thermal (BIPV/T) systems may be utilized to produce useful heat while simultaneously generating electricity from the same building envelope surface. A well known highly efficient collector is the open-loop unglazed transpired collector (UTC) which consists of dark porous cladding through which outdoor air is drawn and heated by absorbed solar radiation. Commercially available photovoltaic systems typically produce electricity with efficiencies up to about 18%. Thus, it is beneficial to obtain much of the normally wasted heat from the systems, possibly by combining UTC with photovoltaics. Combination of BIPV/T and UTC systems for building facades is considered in this paper - specifically, the design of a prototype facade-integrated photovoltaic/thermal system with transpired collector (BIPV/T). A full scale prototype is constructed with 70% of UTC area covered with PV modules specially designed to enhance heat recovery and compared to a UTC of the same area under outdoor sunny conditions with low wind. The orientation of the corrugations in the UTC is horizontal and the black-framed modules are attached so as to facilitate flow into the UTC plenum. While the overall combined thermal efficiency of the UTC is higher than that of the BIPV/T system, the value of the generated energy - assuming that electricity is at least four times more valuable than heat - is between 7% and 17% higher. Also, the electricity is always useful while the heat is usually utilized only in the heating season. The BIPV/T concept is applied to a full scale office building demonstration project in Montreal, Canada. The ratio of photovoltaic area coverage of the UTC may be selected based on the fresh air heating needs of the building, the value of the electricity generated and the available building surfaces. (author)

  9. Ozone deposition and stomatal uptake at flux tower sites

    Science.gov (United States)

    Ducker, J.; Holmes, C.; Schnell, J.; Fares, S.; Keenan, T. F.; Munger, W.; Mammarella, I.

    2017-12-01

    We develop and evaluate a method for estimating O3 deposition and stomatal O3 uptake at FLUXNET tower sites. The method combines standard micrometeorological measurements that are made with the eddy covariance method with a gridded dataset of surface O3 concentration. We evaluate the method at 3 sites where O3 fluxes were measured. This comparison shows that our method reproduces 69-92% of the variability with modest bias. The remaining unexplained variance is due to stomatal conductance filtering methods, non-stomatal parameterizations, representation error in the gridded O3 data and measurement error in . Using our O3 deposition method, we calculate the stomatal O3 uptake at 41 FLUXNET sites in the US and 55 FLUXNET sites in Europe. The spatial patterns in stomatal O3 uptake are driven by the gradients in humidity, which promote stomatal conductance rather than spatial patterns in O3 concentrations alone. Factors such as land cover, land management, and plant functional types are also important underlying factors in the spatial variability in the stomatal O3 uptake throughout the FLUXNET network. With the synthetic O3 flux data we examine the relationship with common concentration-based metrics for plant injuries due to O3, such as mean concentration, AOT40 and W126. We show that concentration-based metrics are poor predictors of O3 flux (R2 ≤ 0.11), when applied across different biomes, but if they must be used, they should be limited to cases where VPD < 1.5 kPa (R2 ≤ 0.28). The synthetic O3 flux data enable evaluation of atmospheric chemistry models at many additional sites.

  10. Chronic gingivitis and aphthous stomatitis relationship hypothesis: A neuroimmunobiological approach

    Directory of Open Access Journals (Sweden)

    Chiquita Prahasanti

    2009-03-01

    Full Text Available Background: Traumatic injuries to the oral mucosa in fixed orthodontic patients are common, especially in the first week of bracket placement, and occasionally lead to the development of aphthous stomatitis or ulcers. Nevertheless, these lesions are selflimiting. Purpose: The objective of this study is to reveal the connection between chronic gingivitis and aphthous stomatitis which is still unclear. Case: A patient with a persistent lesion for more than six months. Case Management: RAS was treated with scaling procedure, the gingival inflammation was healed. However, in this case report, despite the appropriate management procedures had been done, the lesion still worsen and became more painful. Moreover, the symptoms did not heal for more than two weeks. Actually, they had been undergone orthodontic treatment more than six months and rarely suffered from aphthous stomatitis. Coincidentally, at that time they also suffered from chronic gingivitis. It was interesting that after scaling procedures, the ulcer subsides in two days. Conclusion: Recently, the neuroimmunobiological researches which involved neurotransmitters and cytokines on cell-nerve signaling, and heat shock proteins in gingivitis and stomatitis are in progress. Nevertheless, they were done separately, thus do not explain the interrelationship. This proposed new concept which based on an integrated neuroimmunobiological approach could explain the benefit of periodontal treatment, especially scaling procedures, for avoiding prolonged painful episodes and unnecessary medications in aphthous stomatitis. However, for widely acceptance of the chronic gingivitis and aphthous stomatitis relationship, further clinical and laboratory study should be done. Regarding to the relatively fast healing after scaling procedures in this case report; it was concluded that the connection between chronic gingivitis and aphthous stomatitis is possible.

  11. How Reliable Are Heat Pulse Velocity Methods for Estimating Tree Transpiration?

    Directory of Open Access Journals (Sweden)

    Michael A. Forster

    2017-09-01

    Full Text Available Transpiration is a significant component of the hydrologic cycle and its accurate quantification is critical for modelling, industry, and policy decisions. Sap flow sensors provide a low cost and practical method to measure transpiration. Various methods to measure sap flow are available and a popular family of methods is known as heat pulse velocity (HPV. Theory on thermal conductance and convection, that underpins HPV methods, suggests transpiration can be directly estimated from sensor measurements without the need for laborious calibrations. To test this accuracy, transpiration estimated from HPV sensors is compared with an independent measure of plant water use such as a weighing lysimeter. A meta-analysis of the literature that explicitly tested the accuracy of a HPV sensors against an independent measure of transpiration was conducted. Data from linear regression analysis was collated where an R2 of 1 indicates perfect precision and a slope of 1 of the linear regression curve indicates perfect accuracy. The average R2 and slope from all studies was 0.822 and 0.860, respectively. However, the overall error, or deviation from real transpiration values, was 34.706%. The results indicate that HPV sensors are precise in correlating heat velocity with rates of transpiration, but poor in quantifying transpiration. Various sources of error in converting heat velocity into sap velocity and sap flow are discussed including probe misalignment, wound corrections, thermal diffusivity, stem water content, placement of sensors in sapwood, and scaling of point measurements to whole plants. Where whole plant water use or transpiration is required in a study, it is recommended that all sap flow sensors are calibrated against an independent measure of transpiration.

  12. Stomatal density and stomatal index as indicators of paleoatmospheric CO(2) concentration.

    Science.gov (United States)

    Royer, D L.

    2001-03-01

    A growing number of studies use the plant species-specific inverse relationship between atmospheric CO(2) concentration and stomatal density (SD) or stomatal index (SI) as a proxy for paleo-CO(2) levels. A total of 285 previously published SD and 145 SI responses to variable CO(2) concentrations from a pool of 176 C(3) plant species are analyzed here to test the reliability of this method. The percentage of responses inversely responding to CO(2) rises from 40 and 36% (for SD and SI, respectively) in experimental studies to 88 and 94% (for SD and SI, respectively) in fossil studies. The inconsistent experimental responses verify previous concerns involving this method, however the high percentage of fossil responses showing an inverse relationship clearly validates the method when applied over time scales of similar length. Furthermore, for all groups of observations, a positive relationship between CO(2) and SD/SI is found in only stomatal initiation, although the mechanism may involve genetic adaptation and therefore is often not clearly expressed under short CO(2) exposure times.Experimental responses of SD and SI based on open-top chambers (OTCs) inversely relate to CO(2) less often than greenhouse-based responses (P<0.01 for both SD and SI), and should be avoided when experimental responses are required for CO(2) reconstructions. In the combined data set, hypostomatous species follow the inverse relationship more often than amphistomatous species (56 vs. 44% for SD; 69 vs. 32% for SI; P<0.03 for both comparisons). Both the SD and SI of fossil responses are equally likely to inversely relate to CO(2) when exposed to elevated versus subambient CO(2) concentrations (relative to today). This result casts doubt on previous claims that stomata cannot respond to CO(2) concentrations above present-day levels. Although the proportion of SD and SI responses inversely relating to CO(2) are similar, SD is more

  13. Evolutionary Conservation of ABA Signaling for Stomatal Closure1[OPEN

    Science.gov (United States)

    Huang, Yuqing; Dai, Fei; Franks, Peter J.; Nevo, Eviatar; Soltis, Douglas E.; Soltis, Pamela S.; Xue, Dawei; Zhang, Guoping; Pogson, Barry J.

    2017-01-01

    Abscisic acid (ABA)-driven stomatal regulation reportedly evolved after the divergence of ferns, during the early evolution of seed plants approximately 360 million years ago. This hypothesis is based on the observation that the stomata of certain fern species are unresponsive to ABA, but exhibit passive hydraulic control. However, ABA-induced stomatal closure was detected in some mosses and lycophytes. Here, we observed that a number of ABA signaling and membrane transporter protein families diversified over the evolutionary history of land plants. The aquatic ferns Azolla filiculoides and Salvinia cucullata have representatives of 23 families of proteins orthologous to those of Arabidopsis (Arabidopsis thaliana) and all other land plant species studied. Phylogenetic analysis of the key ABA signaling proteins indicates an evolutionarily conserved stomatal response to ABA. Moreover, comparative transcriptomic analysis has identified a suite of ABA-responsive genes that differentially expressed in a terrestrial fern species, Polystichum proliferum. These genes encode proteins associated with ABA biosynthesis, transport, reception, transcription, signaling, and ion and sugar transport, which fit the general ABA signaling pathway constructed from Arabidopsis and Hordeum vulgare. The retention of these key ABA-responsive genes could have had a profound effect on the adaptation of ferns to dry conditions. Furthermore, stomatal assays have shown the primary evidence for ABA-induced closure of stomata in two terrestrial fern species P. proliferum and Nephrolepis exaltata. In summary, we report, to our knowledge, new molecular and physiological evidence for the presence of active stomatal control in ferns. PMID:28232585

  14. Tamarix transpiration along a semiarid river has negligible impact on water resources

    Science.gov (United States)

    McDonald, Alyson K.; Wilcox, Bradford P.; Moore, Georgianne W.; Hart, Charles R.; Sheng, Zhuping; Owens, M. Keith

    2015-07-01

    The proliferation of saltcedar (Tamarix spp.) along regulated rivers in the western United States has transformed riparian plant communities. It is commonly assumed that transpiration by these alien plants has led to large losses of water that would otherwise contribute to streamflow. Control of saltcedar, therefore, has been considered a viable strategy for conserving water and increasing streamflow in these regions. In an effort to better understand the linkage between transpiration by saltcedar and streamflow, we monitored transpiration, stream stage, and groundwater elevations within a saltcedar stand along the Pecos River during June 2004. Transpiration, as determined by sap flow measurements, exhibited a strong diel pattern; stream stage did not. Diel fluctuations in groundwater levels were observed, but only in one well, which was located in the center of the saltcedar stand. In that well, the correlation between maximal transpiration and minimal groundwater elevation was weak (R2 = 0.16). No effects of transpiration were detected in other wells within the saltcedar stand, nor in the stream stage. The primary reason, we believe, is that the saltcedar stand along this reach of the Pecos River has relatively low sapwood area and a limited spatial extent resulting in very low transpiration compared with the stream discharge. Our results are important because they provide a mechanistic explanation for the lack of increase in streamflow following large-scale control of invasive trees along semiarid rivers.

  15. Transpiration of A Mixed Forest Stand: Field Measurements and Model Estimations

    Science.gov (United States)

    Oltchev, A.; Cermak, J.; Nadezhdina, N.; Tatarinov, F.; Gravenhorst, G.

    Transpiration of a mixed spruce-aspen-birch forest stand at the southern part of the Valday Hills in Russia was determined using sap flow measurements and SVAT mod- els. The measurements showed a significant variability of transpiration rates between different species and different trees. Under non-limited soil water conditions broadleaf trees transpired about 10-20% more than spruces trees. Deficit of available water in the upper soil layers had a more pronounced influence on water uptake of spruce than of deciduous tree species due to the shallow spruce root system. Under surplus wa- ter in the upper soil layers the transpiration rates were slightly suppressed both for spruce and for broadleaf tree species. Two one-dimensional multi-layer SVAT mod- els were applied to describe energy and water exchanges between mixed forest stand and the atmosphere. A more simplified MLOD-SVAT model uses averaged biophys- ical properties of different tree species. Estimation of forest water uptake in a more sophisticated EWE-MF model is based on separate description of water uptakes for individual tree species. Comparisons of modelling and measuring results show that under non-limited soil water conditions both modelling approaches allow to describe in a representative way the water uptake and transpiration rates. Under limited soil water conditions more sophisticated model could deduce more representatively the effect of different tree species on forest transpiration. Application of more simplified MLOD-SVAT model can result in an overestimation of daily total forest transpiration up to 50%.

  16. Treatment of radiation- and chemotherapy-induced stomatitis

    Energy Technology Data Exchange (ETDEWEB)

    Carnel, S.B.; Blakeslee, D.B.; Oswald, S.G.; Barnes, M. (Fitzsimons Army Medical Center, Aurora, CO (USA))

    1990-04-01

    Severe stomatitis is a common problem encountered during either radiation therapy or chemotherapy. Most therapeutic regimens are empirical, with no scientific basis. The purpose of this study is to determine the efficacy of various topical solutions in the treatment of radiation- or chemotherapy-induced stomatitis. Eighteen patients were entered into a prospective double-blinded study to test several topical solutions: (1) viscous lidocaine with 1% cocaine; (2) dyclonine hydrochloride 1.0% (Dyclone); (3) kaolin-pectin solution, diphenhydramine plus saline (KBS); and (4) a placebo solution. Degree of pain relief, duration of relief, side effects, and palatability were evaluated. The results showed that Dyclone provided the most pain relief. Dyclone and viscous lidocaine with 1% cocaine provided the longest pain relief, which averaged 50 minutes This study provides objective data and defines useful guidelines for treatment of stomatitis.

  17. [CORRELATION MATRIX OF CHARACTERISTICS OF CHRONIC RECURRENT APHTHOUS STOMATITIS].

    Science.gov (United States)

    Koridze, Kh; Aladashvili, L; Taboridze, I

    2015-09-01

    The purpose of the present work is to study the correlation between the risk factors of chronic recurrent aphthous stomatitis. The research was conducted on 62 patients between ages of 40 and 70 years at Tbilisi Hospital for Veterans of War. The analysis was carried out by Spearman's Rank Correlation method using the statistical package SPSS 11.5. We investigated: harmful habits, professional factors, background and accompanying illnesses, pathology of teeth, focal infection, emotional stress, genetic factors. Correlation matrix between the significant risk factors of chronic recurrent aphthous stomatitis is defined. Multiple correlations have the following factors: industrial dust, focal infections, emotional stress, anemia. Correlation diagram of etiological factors of chronic recurrent aphthous stomatitis is helpful for providing professional and expert services.

  18. Photosynthesis Decrease and Stomatal Control of Gas Exchange in Abies alba Mill. in Response to Vapor Pressure Difference.

    Science.gov (United States)

    Guehl, J M; Aussenac, G

    1987-02-01

    The responses of steady state CO(2) assimilation rate (A), transpiration rate (E), and stomatal conductance (g(s)) to changes in leaf-to-air vapor pressure difference (DeltaW) were examined on different dates in shoots from Abies alba trees growing outside. In Ecouves, a provenance representative of wet oceanic conditions in Northern France, both A and g(s) decreased when DeltaW was increased from 4.6 to 14.5 Pa KPa(-1). In Nebias, which represented the dry end of the natural range of A. alba in southern France, A and g(s) decreased only after reaching peak levels at 9.0 and 7.0 Pa KPa(-1), respectively. The representation of the data in assimilation rate (A) versus intercellular CO(2) partial pressure (C(i)) graphs allowed us to determine how stomata and mesophyll photosynthesis interacted when DeltaW was increased. Changes in A were primarily due to alterations in mesophyll photosynthesis. At high DeltaW, and especially in Ecouves when soil water deficit prevailed, A declined, while C(i) remained approximately constant, which may be interpreted as an adjustment of g(s) to changes in mesophyll photosynthesis. Such a stomatal control of gas exchange appeared as an alternative to the classical feedforward interpretation of E versus DeltaW responses with a peak rate of E. The gas exchange response to DeltaW was also characterized by considerable deviations from the optimization theory of IR Cowan and GD Farquhar (1977 Symp Soc Exp Biol 31: 471-505).

  19. Using ISBA model for partitioning evapotranspiration into soil evaporation and plant transpiration of irrigated crops under semi-arid climate

    Science.gov (United States)

    Aouade, Ghizlane; Jarlan, Lionel; Ezzahar, Jamal; Er-raki, Salah; Napoly, Adrien; Benkaddour, Abdelfettah; Khabba, Said; Boulet, Gilles; Chehbouni, Abdelghani; Boone, Aaron

    2016-04-01

    MEB version simulates more accurately the crop transpiration compared to the standard version. The RMSE and R² were about 0.79 mm and 0.67 for MEB and 1.37mm and 0.65 for standard version. An in-depth analysis of the results points out : (1) a deficiency of the standard version in simulating soil evaporation, in particular after an irrigation event, that directly impact the latent heat fluxes prediction because of two much energy reaching the soil and (2) a significant improvement of the surface temperature predictions with the double energy balance version; an interesting feature in the context of data assimilation; (3) a poor parameterization of the stomatal conductance in the A-gs photosynthetic module that is corrected thanks to a stochastic parameter identification approach. Results have direct implication for the prediction of evapotranspiration and its partition over irrigated crops in semi-arid areas of the South Mediterranean region.

  20. Abscisic acid controlled sex before transpiration in vascular plants.

    Science.gov (United States)

    McAdam, Scott A M; Brodribb, Timothy J; Banks, Jo Ann; Hedrich, Rainer; Atallah, Nadia M; Cai, Chao; Geringer, Michael A; Lind, Christof; Nichols, David S; Stachowski, Kye; Geiger, Dietmar; Sussmilch, Frances C

    2016-10-26

    Sexual reproduction in animals and plants shares common elements, including sperm and egg production, but unlike animals, little is known about the regulatory pathways that determine the sex of plants. Here we use mutants and gene silencing in a fern species to identify a core regulatory mechanism in plant sexual differentiation. A key player in fern sex differentiation is the phytohormone abscisic acid (ABA), which regulates the sex ratio of male to hermaphrodite tissues during the reproductive cycle. Our analysis shows that in the fern Ceratopteris richardii, a gene homologous to core ABA transduction genes in flowering plants [SNF1-related kinase2s (SnRK2s)] is primarily responsible for the hormonal control of sex determination. Furthermore, we provide evidence that this ABA-SnRK2 signaling pathway has transitioned from determining the sex of ferns to controlling seed dormancy in the earliest seed plants before being co-opted to control transpiration and CO 2 exchange in derived seed plants. By tracing the evolutionary history of this ABA signaling pathway from plant reproduction through to its role in the global regulation of plant-atmosphere gas exchange during the last 450 million years, we highlight the extraordinary effect of the ABA-SnRK2 signaling pathway in plant evolution and vegetation function.

  1. Evidence That Drought-Induced Stomatal Closure Is Not an Important Constraint on White Spruce Performance Near the Arctic Treeline in Alaska

    Science.gov (United States)

    Sullivan, P.; Brownlee, A.; Ellison, S.; Sveinbjornsson, B.

    2014-12-01

    peak canopy transpiration under the highest atmospheric vapor pressure deficits observed (>3.0 kPa). Thus, our tree-ring data provide further evidence of what has become known as the "divergence problem" in northern forests, but our physiological measurements suggest that drought-induced stomatal closure may not be the cause.

  2. Gas-exchange response and stomatal and non-stomatal limitations to carbon assimilation of sunflower under salinity.

    Science.gov (United States)

    Steduto; Albrizio; Giorio; Sorrentino

    2000-11-01

    Sunflower (Helianthus annuus) was grown in both open-field and outdoor potted conditions in Southern Italy, and irrigated with water having electrical conductivity ranging between 0.9 and 15.6 dS m(-1) obtained by different NaCl concentrations. The aim of the work was to study the leaf area and photosynthetic responses of sunflower to mild salt stress. The response curve (A/c(i)) of assimilation (A) to leaf internal CO(2) concentration (c(i)) was used to determine leaf gas-exchange parameters, in order to evaluate stomatal and non-stomatal limitations to photosynthesis in relation to salt stress. In the field, a reduction of 19% in leaf area expansion occurred, while no correlation was observed between Psi(l) and stomatal conductance to water vapour (g(sw)) ranging between 0.76 and 1.35 mol m(-2) s(-1). This result was also evident at a higher salinity level reached in the pot experiment where leaf osmotic potential (psi(s)) varied from -1.35 to -2.67 MPa as compared with the field experiment, where psi(s) ranged from -1.15 to -1.42 MPa. Considering the two experiments as a unique data set, the assimilation rate, the stomatal conductance to CO(2) (g(sc)) and the sensitivity of A to c(i) variation (g*) were not significantly influenced by salinity in the whole range of psi(s). As a consequence, the stomatal and non-stomatal limitations to photosynthesis were not affected by salt treatment, averaging around 20 and 80%, respectively. The variation in A (from 44 to 29 µmol m(-2) s(-1)) was paralleled by the variation in g(sc) (from 0.47 to 0.84 mol m(-2) s(-1)), with a remarkable constancy of both c(i) (200+/-12.5 µmol mol(-1)) and normalized water-use efficiency (5+/-0.7 µmol mmol(-1) kPa), showing the optimal behaviour of the plant processes. These findings indicate that, under mild salt stress, the same as observed under water deficit, sunflower controls assimilation mainly by modulating leaf area rather than by stomatal closure, and that non-stomatal limitation

  3. Na+ accumulation in root symplast of sunflower plants exposed to moderate salinity is transpiration-dependent.

    Science.gov (United States)

    Quintero, José Manuel; Fournier, José María; Benlloch, Manuel; Rodríguez-Navarro, Alonso

    2008-08-25

    Twenty-day-old sunflower plants (Helianthus annuus L. cv Sun-Gro 380) grown hydroponically under controlled conditions were used to study the effect of transpiration on Na(+) compartmentalization in roots. The plants were exposed to low Na(+) concentrations (25 mM NaCl) and different environmental humidity conditions over a short time period (8.5 h). Under these conditions, Na(+) was accumulated primarily in the root, but only the Na(+) accumulated in the root symplast was dependent on transpiration, while the Na(+) accumulated in both the shoot and the root apoplast exhibited a low transpiration dependence. Moreover, Na(+) content in the root apoplast was reached quickly (0.25 h) and increased little with time. These results suggest that, in sunflower plants under moderate salinity conditions, Na(+) uptake in the root symplast is mediated by a transport system whose activity is enhanced by transpiration.

  4. Groundwater and unsaturated zone evaporation and transpiration in a semi-arid open woodland

    NARCIS (Netherlands)

    Balugani, E.; Lubczynski, M.W.; Reyes-Acosta, L.; Tol, van der C.; Francés, A.P.; Metselaar, K.

    2017-01-01

    Studies on evapotranspiration partitioning under eddy covariance (EC) towers rarely address the separate effects of transpiration and evaporation on groundwater resources. Such partitioning is important to accurately assess groundwater resources, especially in arid and semi-arid areas. The main

  5. Low-Cost and Light-Weight Transpiration-Cooled Thrust Chambers, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort aims to evaluate the feasibility of using transpiration-cooled Titanium as the primary material in small-scale thrust chambers for in-space...

  6. Preventive effects of Ancer 20 injection against radiation stomatitis

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Naohiko; Nomura, Yasuya; Takano, Shinya (Showa Univ., Tokyo (Japan). School of Medicine) (and others)

    1993-10-01

    Ancer 20 was injected subcutaneously twice a day into 23 patients during the couse of radiation therapy for head and neck cancer, with the aim of preventing radiation stomatitis. Oral mucosa was assessed both subjectively and objectively, in addition to white blood cell counts. Objective findings of oral mucosa revealed grade I in 71%, grade II in 52%, grade III in 14%, and grade IV in 5%. The dose of irradiation needed to produce grade I in 50% was 22.8 Gy. Subjective findings revealed grade I in 67%, grade II in 33%, and grade III in 10%. Irradiation dose needed to produce grade I in 50% was 23.9 Gy. Mucosous damage was slight when the white blood cell count of 6,000/mm[sup 3] was maintained. According to the rate of leukopenia, this drug was effective in 86.4%. These findings showed that Ancer 20 injection is useful in maintaining white blood cell counts and in preventing radiation stomatitis associated with radiation therapy especially to the field of mucous membrane. There was inverse correlation between white blood cell counts and both the occurrence rate and degree of radiation stomatitis. It seemed necessary to maintain white blood cell counts to prevent radiation stomatitis. (N.K.).

  7. mechanisms of drought resistance in grain ii:.stomatal regulation ...

    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT: Earlier research works conducted to identify mechanisms of drought resistance in grain legumes under soil ... maintenance of high plant water potential in common bean under stress was the function of stomatal regulation and/or root ..... available only for maintenance requirements of the plant. On the other ...

  8. Stomatal oscillations in olive trees: analysis and methodological implications.

    Science.gov (United States)

    López-Bernal, Alvaro; García-Tejera, Omar; Testi, Luca; Orgaz, Francisco; Villalobos, Francisco J

    2017-10-13

    Stomatal oscillations have long been disregarded in the literature despite the fact that the phenomenon has been described for a variety of plant species. This study aims to characterize the occurrence of oscillations in olive trees (Olea europaea L.) under different growing conditions and its methodological implications. Three experiments with young potted olives and one with large field-grown trees were performed. Sap flow measurements were always used to monitor the occurrence of oscillations, with additional determinations of trunk diameter variations and leaf-level stomatal conductance, photosynthesis and water potential also conducted in some cases. Strong oscillations with periods of 30-60 min were generally observed for young trees, while large field trees rarely showed significant oscillations. Severe water stress led to the disappearance of oscillations, but moderate water deficits occasionally promoted them. Simultaneous oscillations were also found for leaf stomatal conductance, leaf photosynthesis and trunk diameter, with the former presenting the highest amplitudes. The strong oscillations found in young potted olive trees preclude the use of infrequent measurements of stomatal conductance and related variables to characterize differences between trees of different cultivars or subjected to different experimental treatments. Under these circumstances, our results suggest that reliable estimates could be obtained using measurement intervals below 15 min. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  9. Effects of Moisture and Mycorrhiza on Stomatal Conductance and ...

    African Journals Online (AJOL)

    acer

    ISSN 0794-5698. Effects of Moisture and Mycorrhiza on Stomatal Conductance and Xylem Pressure Potential of Faidherbia albida (Del.) A. Chev. *. 1. M.A. Shinkafi and. 2. A.M. Aduradola. 1Department of Forestry and Fisheries, Usmanu Danfodiyo University, Sokoto, Nigeria. 2Department of Forest Resources Management ...

  10. Gangrenous stomatitis (cancrum oris): clinical features, etiologic factors, and complications.

    Science.gov (United States)

    Chindia, M L; Guthua, S W; Kimaro, S S; Moshy, J

    1997-04-01

    Gangrenous stomatitis (cancrum oris) is a lesion involving the orofacial structures that is primarily seen in areas where the socioeconomic standards are low and there is poor hygiene. The general clinical features, associated etiologic factors, and ensuing complications in eight consecutive cases diagnosed between 1991 and 1995 are presented and discussed.

  11. Evolutionary Conservation of ABA Signaling for Stomatal Closure.

    Science.gov (United States)

    Cai, Shengguan; Chen, Guang; Wang, Yuanyuan; Huang, Yuqing; Marchant, D Blaine; Wang, Yizhou; Yang, Qian; Dai, Fei; Hills, Adrian; Franks, Peter J; Nevo, Eviatar; Soltis, Douglas E; Soltis, Pamela S; Sessa, Emily; Wolf, Paul G; Xue, Dawei; Zhang, Guoping; Pogson, Barry J; Blatt, Michael R; Chen, Zhong-Hua

    2017-06-01

    Abscisic acid (ABA)-driven stomatal regulation reportedly evolved after the divergence of ferns, during the early evolution of seed plants approximately 360 million years ago. This hypothesis is based on the observation that the stomata of certain fern species are unresponsive to ABA, but exhibit passive hydraulic control. However, ABA-induced stomatal closure was detected in some mosses and lycophytes. Here, we observed that a number of ABA signaling and membrane transporter protein families diversified over the evolutionary history of land plants. The aquatic ferns Azolla filiculoides and Salvinia cucullata have representatives of 23 families of proteins orthologous to those of Arabidopsis ( Arabidopsis thaliana ) and all other land plant species studied. Phylogenetic analysis of the key ABA signaling proteins indicates an evolutionarily conserved stomatal response to ABA. Moreover, comparative transcriptomic analysis has identified a suite of ABA-responsive genes that differentially expressed in a terrestrial fern species, Polystichum proliferum These genes encode proteins associated with ABA biosynthesis, transport, reception, transcription, signaling, and ion and sugar transport, which fit the general ABA signaling pathway constructed from Arabidopsis and Hordeum vulgare The retention of these key ABA-responsive genes could have had a profound effect on the adaptation of ferns to dry conditions. Furthermore, stomatal assays have shown the primary evidence for ABA-induced closure of stomata in two terrestrial fern species P proliferum and Nephrolepis exaltata In summary, we report, to our knowledge, new molecular and physiological evidence for the presence of active stomatal control in ferns. © 2017 American Society of Plant Biologists. All Rights Reserved.

  12. The BIG protein distinguishes the process of CO2-induced stomatal closure from the inhibition of stomatal opening by CO2.

    Science.gov (United States)

    He, Jingjing; Zhang, Ruo-Xi; Peng, Kai; Tagliavia, Cecilia; Li, Siwen; Xue, Shaowu; Liu, Amy; Hu, Honghong; Zhang, Jingbo; Hubbard, Katharine E; Held, Katrin; McAinsh, Martin R; Gray, Julie E; Kudla, Jörg; Schroeder, Julian I; Liang, Yun-Kuan; Hetherington, Alistair M

    2018-04-01

    We conducted an infrared thermal imaging-based genetic screen to identify Arabidopsis mutants displaying aberrant stomatal behavior in response to elevated concentrations of CO 2 . This approach resulted in the isolation of a novel allele of the Arabidopsis BIG locus (At3g02260) that we have called CO 2 insensitive 1 (cis1). BIG mutants are compromised in elevated CO 2 -induced stomatal closure and bicarbonate activation of S-type anion channel currents. In contrast with the wild-type, they fail to exhibit reductions in stomatal density and index when grown in elevated CO 2 . However, like the wild-type, BIG mutants display inhibition of stomatal opening when exposed to elevated CO 2 . BIG mutants also display wild-type stomatal aperture responses to the closure-inducing stimulus abscisic acid (ABA). Our results indicate that BIG is a signaling component involved in the elevated CO 2 -mediated control of stomatal development. In the control of stomatal aperture by CO 2 , BIG is only required in elevated CO 2 -induced closure and not in the inhibition of stomatal opening by this environmental signal. These data show that, at the molecular level, the CO 2 -mediated inhibition of opening and promotion of stomatal closure signaling pathways are separable and BIG represents a distinguishing element in these two CO 2 -mediated responses. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

  13. Stem girdling evidences a trade-off between cambial activity and sprouting and dramatically reduces plant transpiration due to feedback inhibition of photosynthesis and hormone signaling

    Directory of Open Access Journals (Sweden)

    Rosana eLópez

    2015-04-01

    Full Text Available The photosynthesis source-sink relationship in young Pinus canariensis seedlings was modified by stem girdling to investigate sprouting and cambial activity, feedback inhibition of photosynthesis, and stem and root hydraulic capacity. Removal of bark tissue showed a trade-off between sprouting and diameter growth. Above the girdle, growth was accelerated but the number of sprouts was almost negligible, whereas below the girdle the response was reversed. Girdling resulted in a sharp decrease in whole plant transpiration and root hydraulic conductance. The reduction of leaf area after girdling was strengthened by the high levels of ABA found in buds which pointed to stronger bud dormancy, preventing a new needle flush. Accumulation of sugars in leaves led to a coordinated reduction in net photosynthesis (AN and stomatal conductance (gS in the short term, but later (gS below 0.07 mol m-2 s-1 AN decreased faster. The decrease in maximal efficiency of photosystem II (FV/FM and the operating quantum efficiency of photosystem II (ΦPSII in girdled plants could suggest photoprotection of leaves, as shown by the vigorous recovery of AN and ΦPSII after reconnection of the phloem. Stem girdling did not affect xylem embolism but increased stem hydraulic conductance above the girdle. This study shows that stem girdling affects not only the carbon balance, but also the water status of the plant.

  14. Predictable 'meta-mechanisms' emerge from feedbacks between transpiration and plant growth and cannot be simply deduced from short-term mechanisms.

    Science.gov (United States)

    Tardieu, François; Parent, Boris

    2017-06-01

    Growth under water deficit is controlled by short-term mechanisms but, because of numerous feedbacks, the combination of these mechanisms over time often results in outputs that cannot be deduced from the simple inspection of individual mechanisms. It can be analysed with dynamic models in which causal relationships between variables are considered at each time-step, allowing calculation of outputs that are routed back to inputs for the next time-step and that can change the system itself. We first review physiological mechanisms involved in seven feedbacks of transpiration on plant growth, involving changes in tissue hydraulic conductance, stomatal conductance, plant architecture and underlying factors such as hormones or aquaporins. The combination of these mechanisms over time can result in non-straightforward conclusions as shown by examples of simulation outputs: 'over production of abscisic acid (ABA) can cause a lower concentration of ABA in the xylem sap ', 'decreasing root hydraulic conductance when evaporative demand is maximum can improve plant performance' and 'rapid root growth can decrease yield'. Systems of equations simulating feedbacks over numerous time-steps result in logical and reproducible emergent properties that can be viewed as 'meta-mechanisms' at plant level, which have similar roles as mechanisms at cell level. © 2016 John Wiley & Sons Ltd.

  15. Salinity controls on plant transpiration and soil water balance

    Science.gov (United States)

    Perri, S.; Molini, A.; Suweis, S. S.; Viola, F.; Entekhabi, D.

    2017-12-01

    Soil salinization and aridification represent a major threat for the food security and sustainable development of drylands. The two problems are deeply connected, and their interplay is expected to be further enhanced by climate change and projected population growth. Salt-affected land is currently estimated to cover around 1.1 Gha, and is particularly widespread in semi-arid to hyper-arid climates. Over 900 Mha of these saline/sodic soils are potentially available for crop or biomass production. Salt-tolerant plants have been recently proposed as valid solution to exploit or even remediate salinized soils. However the effects of salinity on evapotranspiration, soil water balance and the long-term salt mass balance in the soil, are still largely unexplored. In this contribution we analyze the feedback of evapotranspiration on soil salinization, with particular emphasis on the role of vegetation and plant salt-tolerance. The goal is to introduce a simple modeling framework able to shed some light on how (a) soil salinity controls plant transpiration, and (b) salinization itself is favored/impeded by different vegetation feedback. We introduce at this goal a spatially lumped stochastic model of soil moisture and salt mass dynamics averaged over the active soil depth, and accounting for the effect of salinity on evapotranspiration. Here, the limiting effect of salinity on ET is modeled through a simple plant response function depending on both salt concentration in the soil and plant salt-tolerance. The coupled soil moisture and salt mass balance is hence used to obtain the conditional steady-state probability density function (pdf) of soil moisture for given salt tolerance and salinization level, Our results show that salinity imposes a limit in the soil water balance and this limit depends on plant salt-tolerance mainly through the control of the leaching occurrence (tolerant plants exploit water more efficiently than the sensitive ones). We also analyzed the

  16. Transpiration Response and Growth in Pearl Millet Parental Lines and Hybrids Bred for Contrasting Rainfall Environments

    Directory of Open Access Journals (Sweden)

    Susan Medina

    2017-10-01

    Full Text Available Under conditions of high vapor pressure deficit (VPD and soil drying, restricting transpiration is an important avenue to gain efficiency in water use. The question we raise in this article is whether breeding for agro-ecological environments that differ for the rainfall have selected for traits that control plant water use. These are measured in pearl millet materials bred for zones varying in rainfall (8 combinations of parent and F1-hybrids, 18 F1-hybrids and then 40 F1-hybrids. In all cases, we found an agro-ecological variation in the slope of the transpiration response to increasing VPD, and parental line variation in the transpiration response to soil drying within hybrids/parent combinations. The hybrids adapted to lower rainfall had higher transpiration response curves than those from the highest rainfall zones, but showed no variation in how transpiration responded to soil drying. The genotypes bred for lower rainfall zones showed lower leaf area, dry matter, thicker leaves, root development, and exudation, than the ones bred for high rainfall zone when grown in the low VPD environment of the greenhouse, but there was no difference in their root length neither on the root/shoot index in these genotypes. By contrast, when grown under high VPD conditions outdoors, the lower rainfall hybrids had the highest leaf, tiller, and biomass development. Finally, under soil drying the genotypes from the lower rainfall accumulated less biomass than the ones from higher rainfall zone, and so did the parental lines compared to the hybrids. These differences in the transpiration response and growth clearly showed that breeding for different agro-ecological zones also bred for different genotype strategies in relation to traits related to plant water use.Highlights:• Variation in transpiration response reflected breeding for agro-ecological zones• Different growth strategies depended on the environmental conditions• Different ideotypes reflected

  17. Plant, cell, and molecular mechanisms of abscisic-acid regulation of stomatal apertures. A new mechanism for the regulation of stomatal-aperture size in intact leaves: Accumulation of mesophyll-derived sucrose in the guard-cell wall of Vicia faba L.

    Energy Technology Data Exchange (ETDEWEB)

    Lu, P.; Outlaw, W.H. Jr.; Smith, B.G.; Freed, G.A.

    1996-12-31

    At various times after pulse labeling Vicia faba L. leaflets with {sup 14}CO{sub 2}, whole-leaf pieces and rinsed epidermal peels were harvested and subsequently processed for histochemical analysis. Cells dissected from whole leaf retained apoplastic contents whereas those from rinsed peels contained only cytoplastic contents. Sucrose specific radioactivity peaked in palisade cells, 111 GBq{center_dot}mol{sup {minus}1}, at 20 min. In contrast, the {sup 14}C content and sucrose specific radioactivity were very low in guard cells for 20 min, implying little CO{sub 2} incorporation; both then peaked at 40 min. The guard-cell apoplast had a high maximum sucrose specific radioactivity and a high sucrose influx rate. These and other comparisons implied the presence of (a) multiple sucrose pools in mesophyll cells, (b) a localized mesophyll-apoplast region that exchanges with phloem and stomata, and (c) mesophyll-derived sucrose in guard-cell walls sufficient to diminish stomatal opening by {approximately} 4 {micro}m. Factors expected to enhance sucrose accumulation in guard-cell walls are (a) high transpiration rate, which closes stomata, and (b) high apoplastic sucrose concentration, which is elevated when mesophyll-sucrose efflux exceeds translocation. Therefore, multiple physiological factors are integrated in the attenuation of stomatal-aperture size by this previously unrecognized mechanism.

  18. Understanding and altering cell tropism of vesicular stomatitis virus

    OpenAIRE

    Hastie, Eric; Cataldi, Marcela; Marriott, Ian; Grdzelishvili, Valery Z.

    2013-01-01

    Vesicular stomatitis virus (VSV) is a prototypic nonsegmented negative-strand RNA virus. VSV’s broad cell tropism makes it a popular model virus for many basic research applications. In addition, a lack of preexisting human immunity against VSV, inherent oncotropism and other features make VSV a widely used platform for vaccine and oncolytic vectors. However, VSV’s neurotropism that can result in viral encephalitis in experimental animals needs to be addressed for the use of the virus as a sa...

  19. Estimation of Transpiration and Water Use Efficiency Using Satellite and Field Observations

    Science.gov (United States)

    Choudhury, Bhaskar J.; Quick, B. E.

    2003-01-01

    Structure and function of terrestrial plant communities bring about intimate relations between water, energy, and carbon exchange between land surface and atmosphere. Total evaporation, which is the sum of transpiration, soil evaporation and evaporation of intercepted water, couples water and energy balance equations. The rate of transpiration, which is the major fraction of total evaporation over most of the terrestrial land surface, is linked to the rate of carbon accumulation because functioning of stomata is optimized by both of these processes. Thus, quantifying the spatial and temporal variations of the transpiration efficiency (which is defined as the ratio of the rate of carbon accumulation and transpiration), and water use efficiency (defined as the ratio of the rate of carbon accumulation and total evaporation), and evaluation of modeling results against observations, are of significant importance in developing a better understanding of land surface processes. An approach has been developed for quantifying spatial and temporal variations of transpiration, and water-use efficiency based on biophysical process-based models, satellite and field observations. Calculations have been done using concurrent meteorological data derived from satellite observations and four dimensional data assimilation for four consecutive years (1987-1990) over an agricultural area in the Northern Great Plains of the US, and compared with field observations within and outside the study area. The paper provides substantive new information about interannual variation, particularly the effect of drought, on the efficiency values at a regional scale.

  20. Energy and exergy analyses of Photovoltaic/Thermal flat transpired collectors: Experimental and theoretical study

    International Nuclear Information System (INIS)

    Gholampour, Maysam; Ameri, Mehran

    2016-01-01

    Highlights: • A Photovoltaic/Thermal flat transpired collector was theoretically and experimentally studied. • Performance of PV/Thermal flat transpired plate was evaluated using equivalent thermal, first, and second law efficiencies. • According to the actual exergy gain, a critical radiation level was defined and its effect was investigated. • As an appropriate tool, equivalent thermal efficiency was used to find optimum suction velocity and PV coverage percent. - Abstract: PV/Thermal flat transpired plate is a kind of air-based hybrid Photovoltaic/Thermal (PV/T) system concurrently producing both thermal and electrical energy. In order to develop a predictive model, validate, and investigate the PV/Thermal flat transpired plate capabilities, a prototype was fabricated and tested under outdoor conditions at Shahid Bahonar University of Kerman in Kerman, Iran. In order to develop a mathematical model, correlations for Nusselt numbers for PV panel and transpired plate were derived using CFD technique. Good agreement was obtained between measured and simulated values, with the maximum relative root mean square percent deviation (RMSE) being 9.13% and minimum correlation coefficient (R-squared) 0.92. Based on the critical radiation level defined in terms of the actual exergy gain, it was found that with proper fan and MPPT devices, there is no concern about the critical radiation level. To provide a guideline for designers, using equivalent thermal efficiency as an appropriate tool, optimum values for suction velocity and PV coverage percent under different conditions were obtained.

  1. A whole-plant hydraulic capacitance approach to modeling distributed root water uptake and actual transpiration

    Science.gov (United States)

    Vogel, Tomas; Votrubova, Jana; Dohnal, Michal; Dusek, Jaromir

    2017-04-01

    In the present study, we propose a simple transpiration stream model, based on the concept of whole-plant hydraulic capacitance. The suggested algorithm is implemented in a one-dimensional soil water flow model involving vertically distributed macroscopic root water uptake. The proposed transient plant water storage approach is compared with the more conventionally used quasi- steady-state approach. Both approaches are used to simulate soil water flow and diurnal variations of transpiration at a forest site covered with Norway spruce. The key parameter of the transient storage approach - plant hydraulic capacitance - is estimated by comparing the variations of potential transpiration rate, derived from micrometeorological measurements, with observed sap flow intensities. The application of the proposed model leads to improved predictions of root water uptake and actual transpiration rates. The algorithm can be easily implemented into existing soil water flow models and used to simulate transpiration stream responses to varying atmospheric and soil moisture conditions including isohydric and anisohydric plant responses to drought stress.

  2. Residuation theory

    CERN Document Server

    Blyth, T S; Sneddon, I N; Stark, M

    1972-01-01

    Residuation Theory aims to contribute to literature in the field of ordered algebraic structures, especially on the subject of residual mappings. The book is divided into three chapters. Chapter 1 focuses on ordered sets; directed sets; semilattices; lattices; and complete lattices. Chapter 2 tackles Baer rings; Baer semigroups; Foulis semigroups; residual mappings; the notion of involution; and Boolean algebras. Chapter 3 covers residuated groupoids and semigroups; group homomorphic and isotone homomorphic Boolean images of ordered semigroups; Dubreil-Jacotin and Brouwer semigroups; and loli

  3. Regulation of Stomatal Defense by Air Relative Humidity.

    Science.gov (United States)

    Panchal, Shweta; Chitrakar, Reejana; Thompson, Blaine K; Obulareddy, Nisita; Roy, Debanjana; Hambright, W Sealy; Melotto, Maeli

    2016-11-01

    It has long been observed that environmental conditions play crucial roles in modulating immunity and disease in plants and animals. For instance, many bacterial plant disease outbreaks occur after periods of high humidity and rain. A critical step in bacterial infection is entry into the plant interior through wounds and natural openings, such as stomata, which are adjustable microscopic pores in the epidermal tissue. Several studies have shown that stomatal closure is an integral part of the plant immune response to reduce pathogen invasion. In this study, we found that high humidity can effectively compromise Pseudomonas syringae-triggered stomatal closure in both Phaseolus vulgaris and Arabidopsis (Arabidopsis thaliana), which is accompanied by early up-regulation of the jasmonic acid (JA) pathway and simultaneous down-regulation of salicylic acid (SA) pathway in guard cells. Furthermore, SA-dependent response, but not JA-dependent response, is faster in guard cells than in whole leaves, suggesting that the SA signaling in guard cells may be independent from other cell types. Thus, we conclude that high humidity, a well-known disease-promoting environmental condition, acts in part by suppressing stomatal defense and is linked to hormone signaling in guard cells. © 2016 American Society of Plant Biologists. All Rights Reserved.

  4. Responses of transpiration and photosynthesis to reversible changes in photosynthetic foliage area in western red cedar (Thuja plicata) seedlings.

    Science.gov (United States)

    Pepin, S; Livingston, N J; Whitehead, D

    2002-04-01

    Experiments were conducted on 1-year-old western red cedar (Thuja plicata Donn.) seedlings to determine the response of illuminated foliage to reversible changes in total photosynthetic foliage area (L(A)). Reductions in L(A) were brought about by either shading the lower foliage or by reducing the ambient CO2 concentration (c(a)) of the air surrounding the lower part of the seedling. In the latter case, the vapor pressure was also changed so that transpiration rates (E) could be manipulated independently of photosynthetic rates (A). We hypothesized that following such treatments, short-term compensatory changes would occur in stomatal conductance (g(s)) and A of the remaining foliage. These changes would occur in response to hydraulic signals generated by changes in the water potential gradient rather than changes in the distribution of sources and sinks of carbon within the seedling. When a portion of the foliage was shaded, there was an immediate reduction in whole-seedling E and a concomitant increase in g(s), A and E in the remaining illuminated foliage. However, the intercellular CO2 concentration did not change. These compensatory effects were fully reversed after the shade was removed. When the lower foliage A was reduced to < 0 micromol m-2 s-1, by shading or lowering c(a), and E was either unchanged or increased (by adjusting the vapor pressure deficit), there was no significant increase in g(s) and A in the remaining foliage. We conclude that compensatory responses in illuminated foliage occur only when reductions in L(A) are accompanied by a reduction in whole-plant E. The relationship between the reduction in whole-seedling E and the increase in A is highly linear (r2 = 0.68) and confirms our hypothesis of the strong regulation of g(s) by hydraulic signals generated within the seedling. We suggest that the mechanism of the compensatory effects is a combination of both increased CO2 supply, resulting from increased g(s), and a response of the rate of

  5. Dominant controls of transpiration along a hillslope transect inferred from ecohydrological measurements and thermodynamic limits

    Science.gov (United States)

    Renner, Maik; Hassler, Sibylle K.; Blume, Theresa; Weiler, Markus; Hildebrandt, Anke; Guderle, Marcus; Schymanski, Stanislaus J.; Kleidon, Axel

    2016-05-01

    We combine ecohydrological observations of sap flow and soil moisture with thermodynamically constrained estimates of atmospheric evaporative demand to infer the dominant controls of forest transpiration in complex terrain. We hypothesize that daily variations in transpiration are dominated by variations in atmospheric demand, while site-specific controls, including limiting soil moisture, act on longer timescales. We test these hypotheses with data of a measurement setup consisting of five sites along a valley cross section in Luxembourg. Both hillslopes are covered by forest dominated by European beech (Fagus sylvatica L.). Two independent measurements are used to estimate stand transpiration: (i) sap flow and (ii) diurnal variations in soil moisture, which were used to estimate the daily root water uptake. Atmospheric evaporative demand is estimated through thermodynamically constrained evaporation, which only requires absorbed solar radiation and temperature as input data without any empirical parameters. Both transpiration estimates are strongly correlated to atmospheric demand at the daily timescale. We find that neither vapor pressure deficit nor wind speed add to the explained variance, supporting the idea that they are dependent variables on land-atmosphere exchange and the surface energy budget. Estimated stand transpiration was in a similar range at the north-facing and the south-facing hillslopes despite the different aspect and the largely different stand composition. We identified an inverse relationship between sap flux density and the site-average sapwood area per tree as estimated by the site forest inventories. This suggests that tree hydraulic adaptation can compensate for heterogeneous conditions. However, during dry summer periods differences in topographic factors and stand structure can cause spatially variable transpiration rates. We conclude that absorption of solar radiation at the surface forms a dominant control for turbulent heat and

  6. Leaf water relations and stomatal behavior of four allopatric Eucalyptus species planted in Mediterranean southwestern Australia.

    Science.gov (United States)

    White, Don A.; Turner, Neil C.; Galbraith, Jeffrey H.

    2000-11-01

    In 1986, four allopatric Eucalyptus species (E. camaldulensis Dehnh, E. saligna Smith, E. leucoxylon F. Muell and E. platypus Hook.) were planted together in a 480-mm rainfall zone, in 8-m wide contour belts as part of a plan to minimize waterlogging and secondary salinization. Throughout 1997, 1998 and 1999, there was significant inter-specific variation in predawn leaf water potential (Psi(pd)); however, maximum stomatal conductance (g(sm)) only differed significantly between species in mid to late summer. Relationships between g(sm) and Psi(pd) were significant and showed that stomata of E. camaldulensis were significantly more sensitive to Psi(pd), and presumably soil water potential, than stomata of E. leucoxylon or E. platypus. When applied to the Psi(pd) data, these relationships predicted that g(sm), and by inference transpiration, varied much less between species than Psi(pd). Diurnal measurements throughout the season confirmed this prediction, and showed that E. camaldulensis and E. saligna avoided drought by gaining access to deeper water, whereas E. leucoxylon and E. platypus maintained greater g(sm) at a given water stress than E. camaldulensis or E. saligna. Osmotic potentials measured after rehydration and water release curves of the leaves indicated that different mechanisms accounted for the apparent drought tolerance of E. leucoxylon and E. platypus. In summer, E. leucoxylon reduced osmotic potential at full and zero turgor by similar amounts compared with winter. In summer, E. platypus had a significantly lower bulk elastic modulus and relative water content at turgor loss point than E. camaldulensis, E. saligna or E. leucoxylon. This elastic adjustment resulted in a larger difference between osmotic potential at full and zero turgor in summer than in winter. The inherently low osmotic potential in E. leucoxylon and elastic adjustment in E. platypus resulted in turgor loss at a similar and significantly lower water potential than in E

  7. CO2 Sensing and CO2 Regulation of Stomatal Conductance: Advances and Open Questions.

    Science.gov (United States)

    Engineer, Cawas B; Hashimoto-Sugimoto, Mimi; Negi, Juntaro; Israelsson-Nordström, Maria; Azoulay-Shemer, Tamar; Rappel, Wouter-Jan; Iba, Koh; Schroeder, Julian I

    2016-01-01

    Guard cells form epidermal stomatal gas-exchange valves in plants and regulate the aperture of stomatal pores in response to changes in the carbon dioxide (CO2) concentration ([CO2]) in leaves. Moreover, the development of stomata is repressed by elevated CO2 in diverse plant species. Evidence suggests that plants can sense [CO2] changes via guard cells and via mesophyll tissues in mediating stomatal movements. We review new discoveries and open questions on mechanisms mediating CO2-regulated stomatal movements and CO2 modulation of stomatal development, which together function in the CO2 regulation of stomatal conductance and gas exchange in plants. Research in this area is timely in light of the necessity of selecting and developing crop cultivars that perform better in a shifting climate. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Effect of SO/sub 2/ on stomatal aperture and sulfur uptake of woody angiosperm seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Noland, T.L.; Kozlowski, T.T.

    1979-01-01

    Effects of SO/sub 2/ pollution on stomatal aperture and sulfur uptake varied with SO/sub 2/ dosage and plant species. Fumigation of Ulmus americana L. seedlings with 1 ppm SO/sub 2/ for 8 h inhibited stomatal closure and fumigation with 2 ppm SO/sub 2/ for 12 h induced stomatal closure. Sulfur uptake of fumigated Ulmus americana seedlings depended on stomatal aperture and was much higher in the light than in the dark. Fumigation of water-stressed Ginkgo biloba L. seedlings with 2 ppm SO/sub 2/ for 6.5 h tended to prevent stomatal closure. However, the effects of SO/sub 2/ on stomatal aperture were modulated and often overridden by environmental stresses such as low light intensity and drought.

  9. CO2 sensing and CO2 regulation of stomatal conductance: advances and open questions

    Science.gov (United States)

    Engineer, Cawas; Hashimoto-Sugimoto, Mimi; Negi, Juntaro; Israelsson-Nordstrom, Maria; Azoulay-Shemer, Tamar; Rappel, Wouter-Jan; Iba, Koh; Schroeder, Julian

    2015-01-01

    Guard cells form epidermal stomatal gas exchange valves in plants and regulate the aperture of stomatal pores in response to changes in the carbon dioxide (CO2) concentration in leaves. Moreover, the development of stomata is repressed by elevated CO2 in diverse plant species. Evidence suggests that plants can sense CO2 concentration changes via guard cells and via mesophyll tissues in mediating stomatal movements. We review new discoveries and open questions on mechanisms mediating CO2-regulated stomatal movements and CO2 modulation of stomatal development, which together function in CO2-regulation of stomatal conductance and gas exchange in plants. Research in this area is timely in light of the necessity of selecting and developing crop cultivars which perform better in a shifting climate. PMID:26482956

  10. Maximum leaf conductance driven by CO2 effects on stomatal size and density over geologic time

    OpenAIRE

    Franks, Peter J.; Beerling, David J.

    2009-01-01

    Stomatal pores are microscopic structures on the epidermis of leaves formed by 2 specialized guard cells that control the exchange of water vapor and CO2 between plants and the atmosphere. Stomatal size (S) and density (D) determine maximum leaf diffusive (stomatal) conductance of CO2 (gcmax) to sites of assimilation. Although large variations in D observed in the fossil record have been correlated with atmospheric CO2, the crucial significance of similarly large variations in S has been over...

  11. Carbon dioxide and the stomatal control of water balance and photosynthesis in higher plants

    Energy Technology Data Exchange (ETDEWEB)

    Taiz, L.; Zeiger, E.; Mawson, B. T.; Cornish, K.; Radin, J. W.; Turcotte, E. L.; Hercovitz, S.; Tallman, G.; Karlsson, P. E.; Bogomolni, R. A.; Talbott, L. D.; Srivastava, A.

    1992-01-01

    Research continued into the investigation of the effects of carbon dioxide on stomatal control of water balance and photosynthesis in higher plants. Topics discussed this period include a method of isolating a sufficient number of guard cell chloroplasts for biochemical studies by mechanical isolation of epidermal peels; the measurement of stomatal apertures with a digital image analysis system; development of a high performance liquid chromatography method for quantification of metabolites in guard cells; and genetic control of stomatal movements in Pima cotton. (CBS)

  12. Évaluation des caractéristiques des stomates chez le palmier à huile ...

    African Journals Online (AJOL)

    Les résultats ont montré que, sur la face inférieure des feuilles, la densité stomatique est plus importante chez le matériel adulte 50,32 stomates par mm2 que chez le matériel jeune 23,88 stomates par mm2 et, sur la face supérieure des feuilles, cette situation s'inverse 4,77 stomates par mm2 contre 9,21 stomates par mm2.

  13. Effect of Chamomile Mouthwash in the Prevention of Chemotherapy-Induced Stomatitis

    Directory of Open Access Journals (Sweden)

    Reza Shabanlouei

    2006-07-01

    Full Text Available Objective: Stomatitis or Oral Mucositis is a significant problem in patients treated with chemotherapy. The frequency of this side effect is estimated to range from 40% to 100%. Stomatitis is painful and can interfere with eating, drinking, and daily life. For the person with cancer, either condition can also lead to a risk of increased infection, hospitalization, mortality and delay in cancer treatments. The aim of this research is to measure effect of chamomile mouthwash in the protection of chemotherapy induced stomatitis. Materials & Methods: The type of this research is double blind clinical trial for measuring the effects of chamomile mouthwash in the protection of chemotherapy induced stomatitis in Tabriz Ghazzi Oncology Center. 28 patients in case group and 14 patients in control group were involved. Patients (Case group were prescribed qid chamomile for 16 days and two colleagues controlled the mucus of mouth charily who were not been informed about the type of mouthwash. Results: The Findings show that the chamomile mouthwash had significant effect in prevention (stomatitis and pain violence and stomatitis survival of chemotherapy-induced stomatitis (P<0.05. Conclusion: Regarding the fact that the only and prominent way to prevention of chemotherapy-induced stomatitis is the usage of suitable mouthwash, so the usage of chamomile mouthwash is effective in protection of stomatitis in such patients and has improved the quality of treatment and quality of life in patients undergoing chemotherapy.

  14. Evolutionary association of stomatal traits with leaf vein density in Paphiopedilum, Orchidaceae.

    Directory of Open Access Journals (Sweden)

    Shi-Bao Zhang

    Full Text Available Both leaf attributes and stomatal traits are linked to water economy in land plants. However, it is unclear whether these two components are associated evolutionarily.In characterizing the possible effect of phylogeny on leaf attributes and stomatal traits, we hypothesized that a correlated evolution exists between the two. Using a phylogenetic comparative method, we analyzed 14 leaf attributes and stomatal traits for 17 species in Paphiopedilum. Stomatal length (SL, stomatal area (SA, upper cuticular thickness (UCT, and total cuticular thickness (TCT showed strong phylogenetic conservatism whereas stomatal density (SD and stomatal index (SI were significantly convergent. Leaf vein density was correlated with SL and SD whether or not phylogeny was considered. The lower epidermal thickness (LET was correlated positively with SL, SA, and stomatal width but negatively with SD when phylogeny was not considered. When this phylogenetic influence was factored in, only the significant correlation between SL and LET remained.Our results support the hypothesis for correlated evolution between stomatal traits and vein density in Paphiopedilum. However, they do not provide evidence for an evolutionary association between stomata and leaf thickness. These findings lend insight into the evolution of traits related to water economy for orchids under natural selection.

  15. Evolutionary association of stomatal traits with leaf vein density in Paphiopedilum, Orchidaceae.

    Science.gov (United States)

    Zhang, Shi-Bao; Guan, Zhi-Jie; Sun, Mei; Zhang, Juan-Juan; Cao, Kun-Fang; Hu, Hong

    2012-01-01

    Both leaf attributes and stomatal traits are linked to water economy in land plants. However, it is unclear whether these two components are associated evolutionarily. In characterizing the possible effect of phylogeny on leaf attributes and stomatal traits, we hypothesized that a correlated evolution exists between the two. Using a phylogenetic comparative method, we analyzed 14 leaf attributes and stomatal traits for 17 species in Paphiopedilum. Stomatal length (SL), stomatal area (SA), upper cuticular thickness (UCT), and total cuticular thickness (TCT) showed strong phylogenetic conservatism whereas stomatal density (SD) and stomatal index (SI) were significantly convergent. Leaf vein density was correlated with SL and SD whether or not phylogeny was considered. The lower epidermal thickness (LET) was correlated positively with SL, SA, and stomatal width but negatively with SD when phylogeny was not considered. When this phylogenetic influence was factored in, only the significant correlation between SL and LET remained. Our results support the hypothesis for correlated evolution between stomatal traits and vein density in Paphiopedilum. However, they do not provide evidence for an evolutionary association between stomata and leaf thickness. These findings lend insight into the evolution of traits related to water economy for orchids under natural selection.

  16. Guard cell photosynthesis is critical for stomatal turgor production, yet does not directly mediate CO2 - and ABA-induced stomatal closing.

    Science.gov (United States)

    Azoulay-Shemer, Tamar; Palomares, Axxell; Bagheri, Andisheh; Israelsson-Nordstrom, Maria; Engineer, Cawas B; Bargmann, Bastiaan O R; Stephan, Aaron B; Schroeder, Julian I

    2015-08-01

    Stomata mediate gas exchange between the inter-cellular spaces of leaves and the atmosphere. CO2 levels in leaves (Ci) are determined by respiration, photosynthesis, stomatal conductance and atmospheric [CO2 ]. [CO2 ] in leaves mediates stomatal movements. The role of guard cell photosynthesis in stomatal conductance responses is a matter of debate, and genetic approaches are needed. We have generated transgenic Arabidopsis plants that are chlorophyll-deficient in guard cells only, expressing a constitutively active chlorophyllase in a guard cell specific enhancer trap line. Our data show that more than 90% of guard cells were chlorophyll-deficient. Interestingly, approximately 45% of stomata had an unusual, previously not-described, morphology of thin-shaped chlorophyll-less stomata. Nevertheless, stomatal size, stomatal index, plant morphology, and whole-leaf photosynthetic parameters (PSII, qP, qN, FV '/FM' ) were comparable with wild-type plants. Time-resolved intact leaf gas-exchange analyses showed a reduction in stomatal conductance and CO2 -assimilation rates of the transgenic plants. Normalization of CO2 responses showed that stomata of transgenic plants respond to [CO2 ] shifts. Detailed stomatal aperture measurements of normal kidney-shaped stomata, which lack chlorophyll, showed stomatal closing responses to [CO2 ] elevation and abscisic acid (ABA), while thin-shaped stomata were continuously closed. Our present findings show that stomatal movement responses to [CO2 ] and ABA are functional in guard cells that lack chlorophyll. These data suggest that guard cell CO2 and ABA signal transduction are not directly modulated by guard cell photosynthesis/electron transport. Moreover, the finding that chlorophyll-less stomata cause a 'deflated' thin-shaped phenotype, suggests that photosynthesis in guard cells is critical for energization and guard cell turgor production. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

  17. HESS Opinions "a perspective on isotope versus non-isotope approaches to determine the contribution of transpiration to total evaporation"

    NARCIS (Netherlands)

    Sutanto, S. J.; Van Den Hurk, B.; Dirmeyer, P. A.; Seneviratne, S. I.; Röckmann, T.; Trenberth, K. E.; Blyth, E. M.; Wenninger, J.; Hoffmann, G.

    2014-01-01

    Current techniques to disentangle the evaporative fluxes from the continental surface into a contribution evaporated from soils and canopy, or transpired by plants, are under debate. Many isotope-based studies show that transpiration contributes generally more than 70% to the total evaporation,

  18. How soil moisture mediates the influence of transpiration on streamflow at hourly to interannual scales in a forested catchment

    Science.gov (United States)

    G.W. Moore; J.A. Jones; B.J. Bond

    2011-01-01

    The water balance equation dictates that streamflow may be reduced by transpiration. Yet temporal disequilibrium weakens the relationship between transpiration and streamflow in many cases where inputs and outputs are unbalanced. We address two critical knowledge barriers in ecohydrology with respect to time, scale dependence and lags. Study objectives were to...

  19. Modelling annual pasture dynamics: Application to stomatal ozone deposition

    Science.gov (United States)

    González-Fernández, Ignacio; Bermejo, Victoria; Elvira, Susana; Sanz, Javier; Gimeno, Benjamín S.; Alonso, Rocío

    2010-07-01

    Modelling ozone (O 3) deposition for impact risk assessment is still poorly developed for herbaceous vegetation, particularly for Mediterranean annual pastures. High inter-annual climatic variability in the Mediterranean area makes it difficult to develop models characterizing gas exchange behaviour and air pollutant absorption suitable for risk assessment. This paper presents a new model to estimate stomatal conductance (g s) of Trifolium subterraneum, a characteristic species of dehesa pastures. The MEDPAS (MEDiterranean PAStures) model couples 3 modules estimating soil water content (SWC), vegetation growth and gs. The gs module is a reparameterized version of the stomatal component of the EMEP DO 3SE O 3 deposition model. The MEDPAS model was applied to two contrasting years representing typical dry and humid springs respectively and with different O 3 exposures. The MEDPAS model reproduced realistically the gs seasonal and inter-annual variations observed in the field. SWC was identified as the major driver of differences across years. Despite the higher O 3 exposure in the dry year, meteorological conditions favoured 2.1 times higher gs and 56 day longer growing season in the humid year compared to the dry year. This resulted in higher ozone fluxes absorbed by T. subterraneum in the humid year. High inter-family variability was found in gas exchange rates, therefore limiting the relevance of single species O 3 deposition flux modelling for dehesa pastures. Stomatal conductance dynamics at the canopy level need to be considered for more accurate O 3 flux modelling for present and future climate scenarios in the Mediterranean area.

  20. Residue processing

    Energy Technology Data Exchange (ETDEWEB)

    Gieg, W.; Rank, V.

    1942-10-15

    In the first stage of coal hydrogenation, the liquid phase, light and heavy oils were produced; the latter containing the nonliquefied parts of the coal, the coal ash, and the catalyst substances. It was the problem of residue processing to extract from these so-called let-down oils that which could be used as pasting oils for the coal. The object was to obtain a maximum oil extraction and a complete removal of the solids, because of the latter were returned to the process they would needlessly burden the reaction space. Separation of solids in residue processing could be accomplished by filtration, centrifugation, extraction, distillation, or low-temperature carbonization (L.T.C.). Filtration or centrifugation was most suitable since a maximum oil yield could be expected from it, since only a small portion of the let-down oil contained in the filtration or centrifugation residue had to be thermally treated. The most satisfactory centrifuge at this time was the Laval, which delivered liquid centrifuge residue and centrifuge oil continuously. By comparison, the semi-continuous centrifuges delivered plastic residues which were difficult to handle. Various apparatus such as the spiral screw kiln and the ball kiln were used for low-temperature carbonization of centrifuge residues. Both were based on the idea of carbonization in thin layers. Efforts were also being made to produce electrode carbon and briquette binder as by-products of the liquid coal phase.

  1. STOMATITIS AFTOSA REKUREN DAN GANGGUAN FUNGSI OVARIUM (Laporan Kasus

    Directory of Open Access Journals (Sweden)

    Farida Soetiarto

    2015-08-01

    Full Text Available Recurrent aphthous stomatitis (RAS is a common disease of undefine etiology. Many studies have been conducted but the result remain unsatisfied. Fortunately some predisposing factors have been identified and one of predisposing factors is hormonal imbalance. The cases report showed that RAS in ovary disorder and disappear after ovary was amputated, and a case of infertility. IN case of RAS with hormone imbalance as predisposing factor, it is suggested to consider the condition of ovary. This suggestion is based on fact that ovary is producing hormone (estrogen, progesteron whihc influence to oral mucous.

  2. Increasing stomatal conductance in response to rising atmospheric CO2.

    Science.gov (United States)

    Purcell, C; Batke, S P; Yiotis, C; Caballero, R; Soh, W K; Murray, M; McElwain, J C

    2018-01-31

    Studies have indicated that plant stomatal conductance (gs) decreases in response to elevated atmospheric CO2, a phenomenon of significance for the global hydrological cycle. However, gs increases across certain CO2 ranges have been predicted by optimization models. The aim of this work was to demonstrate that under certain environmental conditions, gs can increase in response to elevated CO2. Using (1) an extensive, up-to-date synthesis of gs responses in free air CO2 enrichment (FACE)experiments, (2) in situ measurements across four biomes showing dynamic gs responses to a CO2 rise of ~50 ppm (characterizing the change in this greenhouse gas over the past three decades) and (3) a photosynthesis-stomatal conductance model, it is demonstrated that gs can in some cases increase in response to increasing atmospheric CO2. Field observations are corroborated by an extensive synthesis of gs responses in FACE experiments showing that 11.8 % of gs responses under experimentally elevated CO2 are positive. They are further supported by a strong data-model fit (r2 = 0.607) using a stomatal optimization model applied to the field gs dataset. A parameter space identified in the Farquhar-Ball-Berry photosynthesis-stomatal conductance model confirms field observations of increasing gs under elevated CO2 in hot dry conditions. Contrary to the general assumption, positive gs responses to elevated CO2, although relatively rare, are a feature of woody taxa adapted to warm, low-humidity conditions, and this response is also demonstrated in global simulations using the Community Land Model (CLM4). The results contradict the over-simplistic notion that global vegetation always responds with decreasing gs to elevated CO2, a finding that has important implications for predicting future vegetation feedbacks on the hydrological cycle at the regional level. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For

  3. Effect of bedtime on recurrent aphthous stomatitis in college students.

    Science.gov (United States)

    Ma, Ruiyang; Chen, Hong; Zhou, Tengfei; Chen, Xiyan; Wang, Chaoling; Chen, Yijin; Rao, Songlin; Ge, Lin; Lin, Mei

    2015-02-01

    In this study, we conducted a questionnaire-based survey at Sichuan University to investigate the potential effects of bedtime on recurrent aphthous stomatitis (RAS). An anonymous self-designed questionnaire was adopted to investigate the association between bedtime and RAS in college students at Sichuan University. Statistical analyses were used to identify risk factors for RAS and to explore the relationship between bedtime and RAS. One thousand six students were investigated. High frequency of colds (odds ratio [OR] 2.17; 95% confidence interval [CI] 1.52-3.10; P 0; P 0; P college students. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Outward-Rectifying K^+ Channels in Stomatal Guard Cell Protoplasts

    OpenAIRE

    Shigeru, Hosoi; Moritoshi, Iino; Ken-ichiro, Shimazaki; Tsukuba Research Laboratory, Hamamatsu Photonics; Department of Biology, Tokyo Metropolitan University; Division of Environmental Biology, National Institute for Environmental Studies

    1988-01-01

    Ion channels in stomatal guard cell protoplasts from Vicia faba were examined using the patch-clamp technique. Most ion channels having unit conductance ranging between 10 and 30 pS showed clear outward-rectification in symmetrical 50 mM KCl. The large inside-out membranes contained these outward-rectifiers as the major and relatively stable channels. The channels were K^+ ion-selective. Kinetic analysis revealed that the channels have three conductance states: open, closed and inactivated. T...

  5. Suppression of transpiration due to cloud immersion in a seasonally dry Mexican Weeping Pine plantation

    NARCIS (Netherlands)

    Alvarado-Barrientos, M.S.; Holwerda, F.; Asbjornsen, H.; Dawson, T.E.; Bruijnzeel, L.A.

    2013-01-01

    Cloud immersion affects the water budget of fog-affected forests not only by introducing an additional source of water (via cloud water interception by the canopy), but also by suppressing plant transpiration. The latter effect is often overlooked and not routinely quantified, restricting a complete

  6. Predicting of regional transpiration at elevated atmospheric CO2: influence of the PBL vegetation interaction.

    NARCIS (Netherlands)

    Jacobs, C.M.J.; Bruin, de H.A.R.

    1997-01-01

    A coupled planetary boundary layer (PBL)-vegetation model is used to study the influence of the PBL-vegetation interaction and the ambient CO2 concentration on surface resistance rs and regional transpiration E. Vegetation is described using the big-leaf model in which rs is modeled by means of a

  7. Canopy-scale biophysical controls of transpiration and evaporation in the Amazon Basin

    NARCIS (Netherlands)

    Mallick, Kaniska; Trebs, Ivonne; Boegh, Eva; Giustarini, Laura; Schlerf, Martin; Drewry, Darren T.; Hoffmann, Lucien; Randow, Von Celso; Kruijt, Bart; Araùjo, Alessandro; Saleska, Scott; Ehleringer, James R.; Domingues, Tomas F.; Ometto, Jean Pierre H.B.; Nobre, Antonio D.; Luiz Leal De Moraes, Osvaldo; Hayek, Matthew; William Munger, J.; Wofsy, Steven C.

    2016-01-01

    Canopy and aerodynamic conductances (gC and gA) are two of the key land surface biophysical variables that control the land surface response of land surface schemes in climate models. Their representation is crucial for predicting transpiration (λET) and

  8. Latent manganese deficiency increases transpiration in barley (Hordeum vulgare)

    DEFF Research Database (Denmark)

    Hebbern, Christopher Alan; Laursen, Kristian Holst; Ladegaard, Anne Hald

    2009-01-01

    To investigate if latent manganese (Mn) deficiency leads to increased transpiration, barley plants were grown for 10 weeks in hydroponics with daily additions of Mn in the low nM range. The Mn-starved plants did not exhibit visual leaf symptoms of Mn deficiency, but Chl a fluorescence measurements...

  9. Partitioning evaporation and transpiration in a maize field using heat pulse sensors for evaporation measurement

    Science.gov (United States)

    Evapotranspiration (ET) is the sum of soil water evaporation (E) and plant transpiration (T). E and T occur simultaneously in many systems with varying levels of importance, yet it is often very challenging to distinguish these fluxes separately in the field. Few studies have measured all three term...

  10. Athletic field paint color impacts transpiration and canopy temperature in bermudagrass

    Science.gov (United States)

    Athletic field paints have varying impacts on turfgrass health which have been linked to their ability to alter photosynthetically active radiation (PAR) and photosynthesis based on color. It was further hypothesized they may also alter transpiration and canopy temperature by disrupting gas exchange...

  11. Silver and zinc inhibitors influence transpiration rate and aquaporin transcript levels in intact soybean plants

    Science.gov (United States)

    Some soybean (Glycine max (L.) Merr.) have been identified that expressed limited transpiration rate (TR) above a threshold vapor pressure deficit (VPD). Restriction of TR at high VPD conditions is considered a water conservation trait that allows water to be retained in the soil to benefit of crop...

  12. Transpiration response of upland rice to water deficit changed by different levels of eucalyptus biochar

    Directory of Open Access Journals (Sweden)

    Rogério Gomes Pereira

    2012-05-01

    Full Text Available The objective of this work was to evaluate the effect of eucalyptus biochar on the transpiration rate of upland rice 'BRSMG Curinga' as an alternative means to decrease the effect of water stress on plant growth and development. Two-pot experiments were carried out using a completely randomized block design, in a split-plot arrangement, with six replicates. Main plots were water stress (WS and no-water stress (NWS, and the subplots were biochar doses at 0, 6, 12 and 24% in growing medium (sand. Total transpirable soil water (TTSW, the p factor - defined as the average fraction of TTSW which can be depleted from the root zone before water stress limits growth -, and the normalized transpiration rate (NTR were determined. Biochar addition increased TTSW and the p factor, and reduced NTR. Consequently, biochar addition was able to change the moisture threshold (p factor of the growing medium, up to 12% maximum concentration, delaying the point where transpiration declines and affects yield.

  13. Partitioning evaporation and transpiration in a maize field with heat-pulse sensors used for evaporation

    Science.gov (United States)

    Evaporation (E) and transpiration (T) occur simultaneously in many systems with varying levels of importance, yet terms are typically lumped as evapotranspiration (ET) due to difficulty with distinguishing component fluxes. Few studies have measured all three terms (ET, E, and T), and in the few cas...

  14. Wind speed effects on leaf energy balance, transpiration and water use efficiency

    Science.gov (United States)

    Schymanski, S. J.; Or, D.

    2014-12-01

    Transpiration and heat exchange rates by plant leaves involve coupled physiological processes of significant ecohydrological importance. Prediction of the effects of changing environmental conditions such as irradiance, temperature, humidity and wind speed requires a thorough understanding of these processes. The common assumption that leaf temperature equals air temperature may introduce significant bias into estimates of transpiration rates and water use efficiency (WUE, the amount of carbon gained by photosynthesis per unit of water lost by transpiration). Theoretical considerations and observations suggest that leaf temperatures may deviate substantially from air temperature under typical environmental conditions, leading to greatly modified transpiration rates compared to isothermal conditions. In particular, effects of wind on gas exchange must consider feedbacks with leaf temperature. Systematic quantification of the effects of wind speed on leaf heat and gas exchange rates yield some surprising insights. We found a range of conditions where increased wind speed can suppress transpiration rates. The result reflects unintuitive feedbacks between sensible heat flux, leaf temperature, leaf-to-air vapour pressure deficit and latent heat flux. Modelling results suggest that with high wind speeds the same leaf conductance (for water vapour and carbon dioxide) can be maintained with less evaporative losses. This leads to positive relation between water use efficiency and wind speed across a wide range of conditions. The presentation will report results from a lab experiment allowing separation of the different leaf energy balance components under fully controlled conditions (wind speed, temperature, humidity, irradiance) and put them into perspective with a detailed leaf energy balance model and the commonly used Penman-Monteith equation.

  15. Transpiration of helium and carbon monoxide through a multihundred watt, PICS filter

    International Nuclear Information System (INIS)

    Schaeffer, D.R.

    1976-01-01

    The transpiration of CO through the Multihundred Watt (MHW) filter can be described by Fick's first law or as a first order, reversible reaction. From Fick's first law, a ''diffusion'' coefficient of 7.8 x 10 -4 cm.L/sec (L is the average path length through the filter) was determined. For the first order reversible reaction, a rate constant of 0.0058 hr -1 was obtained for both the forward and reverse reactions (they were assumed to be equal). This corresponds to a half-life of 120 hr. It was also concluded that the rate constants and thus the transpiration rates, which were determined for the test, are smaller than those expected in the IHS. The effect of increasing the number of filters, changing the volumes, and increasing the temperature, changes the rate constant of the transpiration into the PICS to roughly 0.074 hr -1 (t/sub 1 / 2 / = 9.4 hr) and out of the PICS to 0.84 hr -1 (t/sub 1/2/ = 0.8 hr). Of the two suggested mechanisms for the generation of CO inside the IHS, the cyclic process requires a much larger rate of transpiration than the process requiring oxygen exchange of CO given off by the graphite. The data indicate that the cyclic process can provide the CO generation rates observed in the IHS gas taps if there is no delay in time for any other kinetic process involved in the formation of CO or CO 2 . Since the cyclic process (which requires the fastest rate of transpiration) appears possible, this study does not indicate which reaction is occurring but concludes both are possible

  16. Soil moisture and wild olive tree transpiration relationship in a water-limited Mediterranean ecosystem.

    Science.gov (United States)

    Curreli, M.; Montaldo, N.; Oren, R.

    2016-12-01

    Typically, during the dry summers, Mediterranean ecosystems are characterized by a simple dual PFTs system with strong-resistant woody vegetation and bare soil, since grass died. In these conditions the combined use of sap flow measurements, based on Granier's thermo-dissipative probes, eddy covariance technique and soil water content measurements provides a robust estimation of evapotranspiration (ET). An eddy covariance micrometeorological tower, thermo-dissipative probes based on the Granier technique and TDR sensors have been installed in the Orroli site in Sardinia (Italy). The site landscape is a mixture of Mediterranean patchy vegetation types: wild olives, different shrubs and herbaceous species, which died during the summer. 33 sap flow sensors have been installed at the Orroli site into 15 wild olives clumps with different characteristics (tree size, exposition to wind, solar radiation and soil depth). Sap flow measurements show the significantly impacts on transpiration of soil moisture, radiation and vapor pressure deficit (VPD). In addition ET is strongly influenced by the tree position into the clump. Results show a significant difference in sap flow rate for the south exposed trees compared to inside clump and north exposed trees. Using an innovative scaling procedure, the transpiration calculated from sap flow measurements have been compared to the eddy covariance ET. Sap flow measurements show night time uptake allows the recharge of the stem capacity, depleted during the day before due to transpiration. The night uptake increases with increasing VPD and transpiration but surprisingly it is independent to soil water content. Soil moisture probes allow monitoring spatial and temporal dynamics of water content at different soil depth and distance to the trees, and estimating its correlation with hydraulic lift. During the light hours soil moisture is depleted by roots to provide the water for transpiration and during night time the lateral roots

  17. A Glycine soja 14-3-3 protein GsGF14o participates in stomatal and root hair development and drought tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Sun, Xiaoli; Luo, Xiao; Sun, Mingzhe; Chen, Chao; Ding, Xiaodong; Wang, Xuedong; Yang, Shanshan; Yu, Qingyue; Jia, Bowei; Ji, Wei; Cai, Hua; Zhu, Yanming

    2014-01-01

    It is well established that 14-3-3 proteins are key regulators of multiple stress signal transduction cascades. However, the biological functions of soybean 14-3-3 proteins, especially in plant drought response, are not yet known. In this study, we characterized a Glycine soja 14-3-3 gene, GsGF14o, which is involved in plant development and drought response. GsGF14o expression was greatly induced by drought stress, as evidenced by the quantitative real-time PCR and β-glucuronidase (GUS) activity analysis. GsGF14o overexpression in Arabidopsis thaliana resulted in decreased drought tolerance during seed germination and seedling growth. Furthermore, silencing of AtGF14µ, the most homologous 14-3-3 gene of GsGF14o, led to enhanced drought tolerance at both the seed germination and seedling stage. Unexpectedly, GsGF14o transgenic lines showed reduced water loss and transpiration rates compared with wild-type plants, which was demonstrated to be the consequence of the decreased stomatal size. At the same time, the smaller stomata due to GsGF14o overexpression led to a relatively slow net photosynthesis rate, which led to a growth penalty under drought stress. We further demonstrated that GsGF14o overexpression caused deficits in root hair formation and development, and thereby reduced the water intake capacity of the transgenic root system. In addition, GsGF14o overexpression down-regulated the transcript levels of drought-responsive marker genes. Finally, we also investigated the tissue-specific accumulation of GsGF14o by using a GUS activity assay. Collectively, the results presented here confirm that GsGF14o plays a dual role in drought stress responses through its involvement in the regulation of stomatal size and root hair development.

  18. Role of hydraulic and chemical signals in leaves, stems and roots in the stomatal behaviour of olive trees under water stress and recovery conditions.

    Science.gov (United States)

    Torres-Ruiz, Jose M; Diaz-Espejo, Antonio; Perez-Martin, Alfonso; Hernandez-Santana, Virginia

    2015-04-01

    The control of plant transpiration by stomata under water stress and recovery conditions is of paramount importance for plant performance and survival. Although both chemical and hydraulic signals emitted within a plant are considered to play a major role in controlling stomatal dynamics, they have rarely been assessed together. The aims of this study were to evaluate (i) the dynamics of chemical and hydraulic signals at leaf, stem and root level, and (ii) their effect on the regulation of stomatal conductance (gs) during water stress and recovery. Measurements of gs, water potential, abscisic acid (ABA) content and loss of hydraulic functioning at leaf, stem and root level were conducted during a water stress and recovery period imposed on 1-year-old olive plants (Olea europaea L.). Results showed a strong hydraulic segmentation in olive plants, with higher hydraulic functioning losses in roots and leaves than in stems. The dynamics of hydraulic conductance of roots and leaves observed as water stress developed could explain both a protection of the hydraulic functionality of larger organs of the plant (i.e., branches, etc.) and a role in the down-regulation of gs. On the other hand, ABA also increased, showing a similar pattern to gs dynamics, and thus its effect on gs in response to water stress cannot be ruled out. However, neither hydraulic nor non-hydraulic factors were able to explain the delay in the full recovery of gs after soil water availability was restored. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Preparation and Evaluation of Stomatitis Film Using Xyloglucan Containing Loperamide.

    Science.gov (United States)

    Kawano, Yayoi; Sasatsu, Masanaho; Mizutani, Ayako; Hirose, Kaoru; Hanawa, Takehisa; Onishi, Hiraku

    2016-06-01

    Stomatitis induced by radiation therapy or cancer chemotherapy is a factor in sleep disorders and/or eating disorders, markedly decreasing patient quality of life. In recent years, disintegrating oral films that are easy to handle have been developed; therefore, we focused on the formulation of these films. We prepared an adhesive film for the oral cavity using xyloglucan (Xylo), which is a water-soluble macromolecule. We used loperamide, which has been reported to relieve pain caused by stomatitis effectively, as a model drug in this study. Films were prepared from Xylo solutions (3% (w/w)) and hypromellose (HPMC) solutions (1% (w/w)). Xylo and HPMC solutions were mixed at ratios of 1 : 1, 2 : 1, or 3 : 1 for each film, and films 2×2 cm weighing 3 g were prepared and dried at 37°C for 24 h. Physicochemical properties such as strength, adhesiveness, disintegration behavior, and dissolution of loperamide from films were evaluated. Films prepared from Xylo solution alone had sufficient strength and mucosal adhesion. On the other hand, films prepared from a mixture of Xylo and HPMC were inferior to those made from Xylo, but showed sufficient strength and mucosal adhesion and were flexible and easy to handle. The films prepared in this study are useful as adhesion films in the oral cavity.

  20. Development and Characterization of Oral Spray for Stomatitis Containing Irsogladine Maleate.

    Science.gov (United States)

    Kawano, Yayoi; Imamura, Ayano; Nakamura, Tomoe; Akaishi, Mio; Satoh, Mitsutoshi; Hanawa, Takehisa

    2016-12-01

    The stomatitis caused by anticancer agents and radiation therapy deteriorates patient QOL, potentially causing eating disorders as a result of pain. Although gargling and ointments can be used in the treatment of stomatitis, patients must spit out mouthwash after use, while ointment application requires a finger to be inserted into the oral cavity. In contrast, sprays eliminate these potential compliance problems. Therefore, we developed a stomatitis spray that remains on the oral mucosa. It has been reported that irsogladine maleate (IM) is effective against stomatitis via oral administration. IM is water insoluble; thus, it was dissolved with various cyclodextrins (CDs). Furthermore, we examined combination with gum ghatti (GG), a mucoadhesive polymer. The interaction between mucin and GG was examined by Quartz Crystal Microbalance with Dissipation monitoring. We found that GG exhibited mucoadhesion. Furthermore, we examined the healing effects of IM on stomatitis in a stomatitis model hamster. We found that stomatitis healed after direct application of IM. However, the model used in this experiment is not based on stomatitis caused by anticancer agents. Further study is therefore necessary.

  1. [Stomatal response of spring wheat and related affecting factors under different irrigation treatment].

    Science.gov (United States)

    Cheng, Xue-Feng; Zhang, Feng-Yun; Chai, Shou-Xi

    2010-01-01

    Taking three spring wheat cultivars as test materials, a field experiment was conducted to study the effects of different irrigation treatments on the stomatal conductance of the cultivars during their growth period, with the relationships between the stomatal conductance and the environmental factors analyzed. On the basis of winter irrigation with 1800 m3 x hm(-2) of water, three irrigation treatments, i. e., irrigating three times (T1), two times (T2), and once (T3) during spring wheat growth period, were installed, with 1050 m3 x hm(-2) of irrigation water each time. All irrigation treatments had greater effects on the stomatal conductance, which was decreased with the decreasing times of irrigation, and varied with the cultivars. From jointing stage to florescence, the stomatal conductance in all treatments had the same variation trend, i. e., decreased after an initial increase, and reached the peak at heading stage. After florescence, difference occurred among the treatments. In treatment T1, the stomatal conductance of all test cultivars increased after an initial decrease; in treatment T2, the variation patterns of stomatal conductance differed with cultivars; while in treatment T3, the conductance of all cultivars decreased all along. Among the environmental factors, relative atmospheric humidity had the greatest effects on the stomatal conductance, and their correlation coefficient in treatments T2 and T3 reached significant (0.82) and very significant (0.92* *), respectively. The stomatal regulation mechanism of spring wheat adapting to water deficit in Hexi corridor was of feedback manner.

  2. Genetic analysis of differences in stomatal guard cell lengths of bread wheat

    Directory of Open Access Journals (Sweden)

    Наталия Петровна Ламари

    2015-05-01

    Full Text Available Variation in stomatal guard cell length of parental cultivars and its inheritance in F1 and F2 hybrids have been studied after crossing between contrast genotypes of winter wheat (Triticum aestivum L.. Analysis of F2 populations has shown the action of three non-allelic genes in control of stomatal guard cell length of parental cultivars

  3. Stomatal response characteristics of Tradescantia virginiana grown at high relative air humidity

    NARCIS (Netherlands)

    Rezaei Nejad, A.; Meeteren, van U.

    2005-01-01

    Plants produced at high relative air humidity (RH) show poor control of water loss after transferring to low RH, a phenomenon which is thought to be due to their stomatal behaviour. The stomatal anatomy and responses of moderate (55%) and high (90%) RH grown Tradescantia virginiana plants to

  4. Les caractéristiques des stomates des feuilles de Ficus benjamina L ...

    African Journals Online (AJOL)

    Objective: The main objective of this study is to assess the potential of Ficus benjamina stomata to be used as indicators of local air pollution. Methodology: Stomatal prints were taken from the species of study in the vicinity of roads, in residential and industrial areas and parks. Density, pore surface and stomatal resistance ...

  5. Does Size Matter? Atmospheric CO2 May Be a Stronger Driver of Stomatal Closing Rate Than Stomatal Size in Taxa That Diversified under Low CO2

    OpenAIRE

    Elliott-Kingston, Caroline; Haworth, Matthew; Yearsley, Jon M.; Batke, Sven P.; Lawson, Tracy; McElwain, Jennifer C.

    2016-01-01

    (1) One strategy for plants to optimise stomatal function is to open and close their stomata quickly in response to environmental signals. It is generally assumed that small stomata can alter aperture faster than large stomata. (2) We tested the hypothesis that species with small stomata close faster than species with larger stomata in response to darkness by comparing rate of stomatal closure across an evolutionary range of species including ferns, cycads, conifers and angiosperms under co...

  6. Natural variation in stomatal response to closing stimuli among Arabidopsis thaliana accessions after exposure to low VPD as a tool to recognize the mechanism of disturbed stomatal functioning.

    Science.gov (United States)

    Aliniaeifard, Sasan; van Meeteren, Uulke

    2014-12-01

    Stomatal responses to closing stimuli are disturbed after long-term exposure of plants to low vapour pressure deficit (VPD). The mechanism behind this disturbance is not fully understood. Genetic variation between naturally occurring ecotypes can be helpful to elucidate the mechanism controlling stomatal movements in different environments. We characterized the stomatal responses of 41 natural accessions of Arabidopsis thaliana to closing stimuli (ABA and desiccation) after they had been exposed for 4 days to moderate VPD (1.17 kPa) or low VPD (0.23 kPa). A fast screening system was used to test stomatal response to ABA using chlorophyll fluorescence imaging under low O2 concentrations of leaf discs floating on ABA solutions. In all accessions stomatal conductance (gs) was increased after prior exposure to low VPD. After exposure to low VPD, stomata of 39 out of 41 of the accessions showed a diminished ABA closing response; only stomata of low VPD-exposed Map-42 and C24 were as responsive to ABA as moderate VPD-exposed plants. In response to desiccation, most of the accessions showed a normal stomata closing response following low VPD exposure. Only low VPD-exposed Cvi-0 and Rrs-7 showed significantly less stomatal closure compared with moderate VPD-exposed plants. Using principle component analysis (PCA), accessions could be categorized to very sensitive, moderately sensitive, and less sensitive to closing stimuli. In conclusion, we present evidence for different stomatal responses to closing stimuli after long-term exposure to low VPD across Arabidopsis accessions. The variation can be a useful tool for finding the mechanism of stomatal malfunctioning. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  7. Evaluating potential impacts of species conversion on transpiration in the Piedmont of North Carolina

    Science.gov (United States)

    Boggs, J.; Treasure, E.; Simpson, G.; Domec, J.; Sun, G.; McNulty, S.

    2010-12-01

    Land management practices that include species conversion or vegetation manipulation can have consequences to surface water availability, groundwater recharge, streamflow generation, and water quality through altering the transpiration processes in forested watersheds. Our objective in this study is to compare stand water use or transpiration in a piedmont mixed hardwood stand (i.e., present stand) to five hypothetical single species stands (i.e., management scenarios), [Quercus spp. (oak), Acer Rubrum (red maple), Liquidambar styraciflua (sweetgum), Liriodendron tulipifera (tulip poplar), and Pinus Taeda (loblolly pine]. Since October 2007, six watersheds with a flume or v-notch weir installed at the watershed outlet have been monitored for baseline streamflow rates (mm d-1). In the summer of 2010, five trees from each of the above species were instrumented with sap flow sensors in the riparian upland of one watershed to develop linkages between stand stream runoff and transpiration. The sap flow or thermal heat dissipation method was used to calculate tree sap flux density for the mixed hardwood stand. Tree sapwood area and stand tree density were then used to compute stand transpiration rates, mm d-1, from June - August 2010. The parameters of the hypothetical single species stands were based on values determined from mixed hardwood stand conditions (e.g., the same stand sapwood area and stand tree density were applied to each option). The diameter at beast height of the monitored trees ranged from 10 cm to 38 cm with a water use range of 1.8 kg d-1 to 104 kg d-1. From our preliminary data, we found daily transpiration from the mixed hardwood stand (2.8 mm d-1 ± 0.06) was significantly (p < 0.05) lower than daily transpiration from the red maple (3.7 mm d-1 ± 0.14) and tulip poplar (3.5 mm d-1 ± 0.12) single species stand management option and significantly (p < 0.05) higher than the loblolly pine (2.3 mm d-1 ± 0.08), sweetgum (2.1 mm d-1 ± 0.08) and oak

  8. Transpiration of Eucalyptus woodlands across a natural gradient of depth-to-groundwater.

    Science.gov (United States)

    Zolfaghar, Sepideh; Villalobos-Vega, Randol; Zeppel, Melanie; Cleverly, James; Rumman, Rizwana; Hingee, Matthew; Boulain, Nicolas; Li, Zheng; Eamus, Derek

    2017-07-01

    Water resources and their management present social, economic and environmental challenges, with demand for human consumptive, industrial and environmental uses increasing globally. However, environmental water requirements, that is, the allocation of water to the maintenance of ecosystem health, are often neglected or poorly quantified. Further, transpiration by trees is commonly a major determinant of the hydrological balance of woodlands but recognition of the role of groundwater in hydrological balances of woodlands remains inadequate, particularly in mesic climates. In this study, we measured rates of tree water-use and sapwood 13C isotopic ratio in a mesic, temperate Eucalypt woodland along a naturally occurring gradient of depth-to-groundwater (DGW), to examine daily, seasonal and annual patterns of transpiration. We found that: (i) the maximum rate of stand transpiration was observed at the second shallowest site (4.3 m) rather than the shallowest (2.4 m); (ii) as DGW increased from 4.3 to 37.5 m, stand transpiration declined; (iii) the smallest rate of stand transpiration was observed at the deepest (37.5 m) site; (iv) intrinsic water-use efficiency was smallest at the two intermediate DGW sites as reflected in the Δ13C of the most recently formed sapwood and largest at the deepest and shallowest DGW sites, reflecting the imposition of flooding at the shallowest site and the inaccessibility of groundwater at the deepest site; and (v) there was no evidence of convergence in rates of water-use for co-occurring species at any site. We conclude that even in mesic environments groundwater can be utilized by trees. We further conclude that these forests are facultatively groundwater-dependent when groundwater depth is <9 m and suggest that during drier-than-average years the contribution of groundwater to stand transpiration is likely to increase significantly at the three shallowest DGW sites. © The Author 2017. Published by Oxford University Press. All

  9. Effects of thinning intensities on transpiration and productivity of 50-year-old Pinus koraeinsis stands

    Science.gov (United States)

    Park, J.; Kim, T.; Cho, S.; Ryu, D.; Moon, M.; Kim, H. S.

    2015-12-01

    This study investigated the effects of thinning intensities on stand transpiration and productivity of 50-year-old Korean pine forests for three years. Forest thinning, which remove some fraction of trees from stand, alters the microclimatic conditions such as radiation distribution within canopy, vapor pressure deficit, and amount of available soil water. These changes influence on the tree water use, and related tree growth. Thinning was conducted on March, 2012 with two intensities (Control, Light-thinning, and Heavy-thinning). Transpiration was estimated from sap flux density, which was measured with Granier-type thermal dissipation sensors. Tree diameter growth was measured with dendrometer, and converted to tree productivity using allometric equations developed specifically in our study sites.The climatic conditions showed remarkable differences among three years. In 2012, total precipitation was highest but spring was dry. 2013 was normal year with frequent rain events. In contrast, 2014 was hot and extremely dry. Stand transpiration was initially decreased ca. 20% and 42% on light-thinning and heavy-thinning stand, respectively. In second year, it gradually recovered in both thinning intensities, and was 19% and 37% lower on light-thinning and heavy-thinning stand, respectively. However, the recovery trends were different between two thinning intensities. Transpiration of heavy-thinning stand was recovered slowly than that of light thinning stand. In 2014, heavy-thinning stand transpired ca. 5% more than control plot in early growing season, but severe drought had negative effects that caused reduction of stand transpiration in thinned stand on late growing season. The tree-level productivity was increased initially ca. 24% and 28% on light-thinning and heavy-thinning stand, respectively. During the following growing seasons, this thinning-induced enhancement of productivity was diminished in light-thinning stand (21% in 2013 and 20% in 2014), but was

  10. Residual risk

    African Journals Online (AJOL)

    ing the residual risk of transmission of HIV by blood transfusion. An epidemiological approach assumed that all HIV infections detected serologically in first-time donors were pre-existing or prevalent infections, and that all infections detected in repeat blood donors were new or incident infections. During 1986 - 1987,0,012%.

  11. Transpiration and root development of urban trees in structural soil stormwater reservoirs.

    Science.gov (United States)

    Bartens, Julia; Day, Susan D; Harris, J Roger; Wynn, Theresa M; Dove, Joseph E

    2009-10-01

    Stormwater management that relies on ecosystem processes, such as tree canopy interception and rhizosphere biology, can be difficult to achieve in built environments because urban land is costly and urban soil inhospitable to vegetation. Yet such systems offer a potentially valuable tool for achieving both sustainable urban forests and stormwater management. We evaluated tree water uptake and root distribution in a novel stormwater mitigation facility that integrates trees directly into detention reservoirs under pavement. The system relies on structural soils: highly porous engineered mixes designed to support tree root growth and pavement. To evaluate tree performance under the peculiar conditions of such a stormwater detention reservoir (i.e., periodically inundated), we grew green ash (Fraxinus pennsylvanica Marsh.) and swamp white oak (Quercus bicolor Willd.) in either CUSoil or a Carolina Stalite-based mix subjected to three simulated below-system infiltration rates for two growing seasons. Infiltration rate affected both transpiration and rooting depth. In a factorial experiment with ash, rooting depth always increased with infiltration rate for Stalite, but this relation was less consistent for CUSoil. Slow-drainage rates reduced transpiration and restricted rooting depth for both species and soils, and trunk growth was restricted for oak, which grew the most in moderate infiltration. Transpiration rates under slow infiltration were 55% (oak) and 70% (ash) of the most rapidly transpiring treatment (moderate for oak and rapid for ash). We conclude this system is feasible and provides another tool to address runoff that integrates the function of urban green spaces with other urban needs.

  12. Groundwater and unsaturated zone evaporation and transpiration in a semi-arid open woodland

    Science.gov (United States)

    Balugani, E.; Lubczynski, M. W.; Reyes-Acosta, L.; van der Tol, C.; Francés, A. P.; Metselaar, K.

    2017-04-01

    Studies on evapotranspiration partitioning under eddy covariance (EC) towers rarely address the separate effects of transpiration and evaporation on groundwater resources. Such partitioning is important to accurately assess groundwater resources, especially in arid and semi-arid areas. The main objective of this study was to partition (evaluate separately) the evaporation and transpiration components of evapotranspiration, originated either from saturated or unsaturated zone, and estimate their contributions in a semi-arid area characterized by relatively shallow groundwater Table (0-10 m deep). Evapotranspiration, tree transpiration and subsurface evaporation were estimated with EC tower, using sap flow methods and HYDRUS1D model, respectively. To set up the HYDRUS1D model, soil material properties, soil moisture, soil temperature, soil matric potential and water table depth were measured in the area. The tree transpiration was sourced into groundwater and unsaturated zone components (∼0.017 mm d-1 for both) and accounted for only ∼6% of the evapotranspiration measured by the EC tower (∼0.565 mm d-1), due to the low canopy coverage in the study area (7%). The subsurface evaporation fluxes were also sourced into groundwater and unsaturated zone components using the SOURCE package, and their relative relevance in total evapotranspiration was assessed. Subsurface evaporation was the main flux year-round (∼0.526 mm d-1). During late autumn, winter and early spring time, the unsaturated zone evaporation was dominant, while in dry summer the relevance of groundwater evaporation increased, reaching one third of evapotranspiration, although errors in the water balance closure point still at its possible underestimation. The results show that, in arid and semi-arid areas with sparse vegetation, the often neglected groundwater evaporation is a relevant contribution to evapotranspiration, and that water vapor flow should be taken into account in the calculation of

  13. Plant transpiration and net entropy exchange on the Earth’s surface in a Czech watershed

    Czech Academy of Sciences Publication Activity Database

    Tesař, Miroslav; Šír, Miloslav; Lichner, Ľ.; Čermák, J.

    2007-01-01

    Roč. 62, č. 5 (2007), s. 547-551 ISSN 0006-3088 R&D Projects: GA AV ČR 1QS200420562; GA ČR GA205/05/2312 Institutional research plan: CEZ:AV0Z20600510 Keywords : entropy * Gaia theory * hydrologic cycle * plant transpiration Subject RIV: DA - Hydrology ; Limnology Impact factor: 0.207, year: 2007

  14. Epicuticular wax on cherry laurel (Prunus laurocerasus) leaves does not constitute the cuticular transpiration barrier.

    Science.gov (United States)

    Zeisler, Viktoria; Schreiber, Lukas

    2016-01-01

    Epicuticular wax of cherry laurel does not contribute to the formation of the cuticular transpiration barrier, which must be established by intracuticular wax. Barrier properties of cuticles are established by cuticular wax deposited on the outer surface of the cuticle (epicuticular wax) and in the cutin polymer (intracuticular wax). It is still an open question to what extent epi- and/or intracuticular waxes contribute to the formation of the transpiration barrier. Epicuticular wax was mechanically removed from the surfaces of isolated cuticles and intact leaf disks of cherry laurel (Prunus laurocerasus L.) by stripping with different polymers (collodion, cellulose acetate and gum arabic). Scanning electron microscopy showed that two consecutive treatments with all three polymers were sufficient to completely remove epicuticular wax since wax platelets disappeared and cuticle surfaces appeared smooth. Waxes in consecutive polymer strips and wax remaining in the cuticle after treatment with the polymers were determined by gas chromatography. This confirmed that two treatments of the polymers were sufficient for selectively removing epicuticular wax. Water permeability of isolated cuticles and cuticles covering intact leaf disks was measured using (3)H-labelled water before and after selectively removing epicuticular wax. Cellulose acetate and its solvent acetone led to a significant increase of cuticular permeability, indicating that the organic solvent acetone affected the cuticular transpiration barrier. However, permeability did not change after two subsequent treatments with collodion and gum arabic or after treatment with the corresponding solvents (diethyl ether:ethanol or water). Thus, in the case of P. laurocerasus the epicuticular wax does not significantly contribute to the formation of the cuticular transpiration barrier, which evidently must be established by the intracuticular wax.

  15. Transpiration effect on the uptake and distribution of bromacil, nitrobenzene, and phenol in soybean plants

    International Nuclear Information System (INIS)

    McFarlane, J.C.; Pfleeger, T.; Fletcher, J.

    1987-01-01

    The influence of transpiration rate on the uptake and translocation of two industrial waste compounds, phenol and nitrobenzene, and one pesticide, 5-bromo-3-sec-butyl-6-methyluracil (bromacil), was examined. Carbon-14 moieties of each compound were provided separately in hydroponic solution to mature soybean plants maintained under three humidity conditions. The uptake of each compound was determined by monitoring the removal of 14 C from the hydroponic solution. The extent to which 14 C was adsorbed to roots and translocated to plant shoots and leaves was examined by assaying root and shoot parts for 14 C. Bromacil was taken up slower than the other chemicals, had the most 14 C translocated to the shoot, and the amount translocated to the shoot responded directly to the rate of transpiration. In contrast, both phenol and nitrobenzene were rapidly lost from solution and bound to the roots. Less than 1.5% of the 14 C from phenol or nitrobenzene was translocated to the plant shoots. Increased transpiration rates had little influence on root binding of 14 C; however, increasing transpiration rate from low to medium was associated with an increased uptake of nitrobenzene. The three chemicals studied have similar Log K/sub ow/ values, but their interactions with soybean were not the same. Thus, despite the usefulness of the octanol/water partitioning coefficient in predicting the fate of organic chemicals in animals and in correlating with root binding and plant uptake for many pesticides, log K/sub ow/ may not be equally useful in describing uptake and binding of nonpesticide chemicals in plants

  16. Does smoking really protect from recurrent aphthous stomatitis?

    Directory of Open Access Journals (Sweden)

    Faleh A Sawair

    2010-11-01

    Full Text Available Faleh A SawairFaculty of Dentistry, University of Jordan, Amman, JordanPurpose: To study the effect of smoking on the prevalence of recurrent aphthous stomatitis (RAS and to examine whether intensity and duration of smoking influence RAS lesions.Subjects and methods: A cross-sectional survey was conducted on a random sample of 1000 students of The University of Jordan, Amman, between May and September 2008. Sociodemographic factors and details about smoking habits and RAS in last 12 months were collected.Results: Annual prevalence (AP of RAS was 37.1%. Tobacco use was common among students: 30.2% were current smokers and 2.8% were exsmokers. AP was not significantly influenced by students’ age, gender, marital status, college, and household income but was significantly affected by place of living (P = 0.02 and presence of chronic diseases (P = 0.03. No significant difference in AP of RAS was found between smokers and nonsmokers. Cigarette smokers who smoked heavily and for a longer period of time had significantly less AP of RAS when compared to moderate smokers and those who smoked for a shorter period of time. The protective effect of smoking was only noticed when there was heavy cigarette smoking (>20 cigarettes/day (P = 0.021 or smoking for long periods of time (>5 years (P = 0.009. Nevertheless, no significant associations were found between intensity or duration of smoking and clinical severity of RAS lesions.Conclusion: The “protective effect” of smoking on RAS was dose- and time-dependent. When lesions are present, smoking had no effect on RAS severity.Keywords: recurrent aphthous stomatitis, smoking, prevalence

  17. Photodynamic antimicrobial therapy in the treatment of denture stomatitis

    International Nuclear Information System (INIS)

    Senna, Andre Machado de

    2012-01-01

    Denture stomatitis (DS), also called chronic atrophic candidiasis, is the most common oral fungal infection in denture wearers. It has a multifactorial etiology, but the presence of Candida spp. biofilm on the denture is considered the most important factor for the establishment of the DS. This study aimed to evaluate the treatment of DS through the use of photodynamic antimicrobial therapy (PAT), mediated by methylene blue. For this purpose, preclinical studies and clinical trials were performed. Simulators prototypes dentures were made of methyl methacrylate polymer to serve as a basis for biofilm growth of the following species of Candida: C. albicans, C. glabrata, C. dubliniensis, C. krusei, C. tropicalis, C. parapsilosis and C. guilliermondii. Methylene blue solution at a concentration of 450 μg/mL was used as a photosensitizer. The prototypes and biofilms were irradiated with a laser of wavelength of 660 nm, potency of 100 mW, for 80 seconds. For the clinical study, subjects were divided into two groups. The first group received conventional treatment based on the use of antifungal Miconazole. The second group received the treatment by PAT. The preclinical results showed that all species of the genus Candida were susceptible to PAT, with a reduction in colonies that ranged from 2.48 to 3.93 log 10 . Clinical outcomes were evaluated for the reduction of colonies of Candida spp. located in the mucosa and in the prosthesis and relative to the improvement of the clinical aspect of the affected mucosa. Both the conventional therapy and PAT were effective in treating DS. There was no significant statistical difference between PAT and conventional treatment for any of the factors evaluated. Thus, it was concluded that PAT is effective in the treatment of denture stomatitis. (author)

  18. Residual basins

    International Nuclear Information System (INIS)

    D'Elboux, C.V.; Paiva, I.B.

    1980-01-01

    Exploration for uranium carried out over a major portion of the Rio Grande do Sul Shield has revealed a number of small residual basins developed along glacially eroded channels of pre-Permian age. Mineralization of uranium occurs in two distinct sedimentary units. The lower unit consists of rhythmites overlain by a sequence of black shales, siltstones and coal seams, while the upper one is dominated by sandstones of probable fluvial origin. (Author) [pt

  19. Within-field advection enhances evaporation and transpiration in a vineyard in an arid environment

    Science.gov (United States)

    Kool, Dilia; Ben-Gal, Alon; Agam, Nurit

    2017-04-01

    Advection of hot air from a warmer to a cooler surface is known to enhance evaporation through additional supply of energy, provided that water is readily available. This study investigated advection in an isolated irrigated vineyard in the Negev desert, over a period of several months under changing plant cover and environmental conditions, and for different degrees of water availability. Field, canopy, and soil energy balance fluxes were assessed, as well as likely indicators of advection such as wind speed, VPD, vertical temperature gradients between the soil, the canopy air space, and the air, and lateral temperature gradients between the vineyard and the surrounding desert. It was found that for a period from May to July, advection enhanced transpiration by 8%, of which an estimated 80% was soil-to-canopy advection and 20% was local advection. At times, soil-to-canopy advection was responsible for as much as 30-40% of transpiration. Wet irrigated strips likewise experienced soil-to-soil advection from drier soil, but to a much lesser degree. A surprisingly large difference was observed in the contribution of advection to transpiration between June (2%) and July (11%), which had almost identical environmental conditions. This indicates that small changes in the agro-system could have a large impact on within-field advection, and that systems could potentially be managed to reduce or enhance advection.

  20. Effects of dew deposition on transpiration and carbon uptake in leaves

    Science.gov (United States)

    Gerlein-Safdi, C.; Koohafkan, M.; Chung, M.; Rockwell, F. E.; Thompson, S. E.; Caylor, K. K.

    2017-12-01

    Dew deposition occurs in ecosystems worldwide, even in the driest deserts and in times of drought. Although some species absorb dew water directly via foliar uptake, a ubiquitous effect of dew on plant water balance is the interference of dew droplets with the leaf energy balance, which increases leaf albedo and emissivity and decreases leaf temperature through dew evaporation. Dew deposition frequency and amount are expected to be affected by changing environmental conditions, with unknown consequences for plant water stress and ecosystem carbon, water and energy fluxes. Here we present a simple leaf energy balance that characterizes the effect of deposition and the evaporation of dew on leaf energy balance, transpiration, and carbon uptake. The model is driven by five common meteorological variables and shows very good agreement with leaf wetness sensor data from the Blue Oak Ranch Reserve in California. We explore the tradeoffs between energy, water, and carbon balances for leaves of different sizes across a range of relative humidity, wind speed, and air temperature conditions. Our results show significant water savings from transpiration suppression up to 30% for leaf characteristic lengths of 50 cm due to the decrease in leaf temperature. C. 25% of water savings from transpiration suppression in smaller leaves arise from the effect of dew droplets on leaf albedo. CO2 assimilation is decreased by up to 15% by the presence of dew, except for bigger leaves in windspeed conditions below 1 m/s when an increase in assimilation is expected.

  1. Limited-transpiration response to high vapor pressure deficit in crop species.

    Science.gov (United States)

    Sinclair, Thomas R; Devi, Jyostna; Shekoofa, Avat; Choudhary, Sunita; Sadok, Walid; Vadez, Vincent; Riar, Mandeep; Rufty, Thomas

    2017-07-01

    Water deficit under nearly all field conditions is the major constraint on plant yields. Other than empirical observations, very little progress has been made in developing crop plants in which specific physiological traits for drought are expressed. As a consequence, there was little known about under what conditions and to what extent drought impacts crop yield. However, there has been rapid progress in recent years in understanding and developing a limited-transpiration trait under elevated atmospheric vapor pressure deficit to increase plant growth and yield under water-deficit conditions. This review paper examines the physiological basis for the limited-transpiration trait as result of low plant hydraulic conductivity, which appears to be related to aquaporin activity. Methodology was developed based on aquaporin involvement to identify candidate genotypes for drought tolerance of several major crop species. Cultivars of maize and soybean are now being marketed specifically for arid conditions. Understanding the mechanism of the limited-transpiration trait has allowed a geospatial analyses to define the environments in which increased yield responses can be expected. This review highlights the challenges and approaches to finally develop physiological traits contributing directly to plant improvement for water-limited environments. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. An abscisic acid-independent oxylipin pathway controls stomatal closure and immune defense in Arabidopsis.

    Science.gov (United States)

    Montillet, Jean-Luc; Leonhardt, Nathalie; Mondy, Samuel; Tranchimand, Sylvain; Rumeau, Dominique; Boudsocq, Marie; Garcia, Ana Victoria; Douki, Thierry; Bigeard, Jean; Laurière, Christiane; Chevalier, Anne; Castresana, Carmen; Hirt, Heribert

    2013-01-01

    Plant stomata function in innate immunity against bacterial invasion and abscisic acid (ABA) has been suggested to regulate this process. Using genetic, biochemical, and pharmacological approaches, we demonstrate that (i) the Arabidopsis thaliana nine-specific-lipoxygenase encoding gene, LOX1, which is expressed in guard cells, is required to trigger stomatal closure in response to both bacteria and the pathogen-associated molecular pattern flagellin peptide flg22; (ii) LOX1 participates in stomatal defense; (iii) polyunsaturated fatty acids, the LOX substrates, trigger stomatal closure; (iv) the LOX products, fatty acid hydroperoxides, or reactive electrophile oxylipins induce stomatal closure; and (v) the flg22-mediated stomatal closure is conveyed by both LOX1 and the mitogen-activated protein kinases MPK3 and MPK6 and involves salicylic acid whereas the ABA-induced process depends on the protein kinases OST1, MPK9, or MPK12. Finally, we show that the oxylipin and the ABA pathways converge at the level of the anion channel SLAC1 to regulate stomatal closure. Collectively, our results demonstrate that early biotic signaling in guard cells is an ABA-independent process revealing a novel function of LOX1-dependent stomatal pathway in plant immunity.

  3. An abscisic acid-independent oxylipin pathway controls stomatal closure and immune defense in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Jean-Luc Montillet

    Full Text Available Plant stomata function in innate immunity against bacterial invasion and abscisic acid (ABA has been suggested to regulate this process. Using genetic, biochemical, and pharmacological approaches, we demonstrate that (i the Arabidopsis thaliana nine-specific-lipoxygenase encoding gene, LOX1, which is expressed in guard cells, is required to trigger stomatal closure in response to both bacteria and the pathogen-associated molecular pattern flagellin peptide flg22; (ii LOX1 participates in stomatal defense; (iii polyunsaturated fatty acids, the LOX substrates, trigger stomatal closure; (iv the LOX products, fatty acid hydroperoxides, or reactive electrophile oxylipins induce stomatal closure; and (v the flg22-mediated stomatal closure is conveyed by both LOX1 and the mitogen-activated protein kinases MPK3 and MPK6 and involves salicylic acid whereas the ABA-induced process depends on the protein kinases OST1, MPK9, or MPK12. Finally, we show that the oxylipin and the ABA pathways converge at the level of the anion channel SLAC1 to regulate stomatal closure. Collectively, our results demonstrate that early biotic signaling in guard cells is an ABA-independent process revealing a novel function of LOX1-dependent stomatal pathway in plant immunity.

  4. Stomatal limitation to carbon gain in Paphiopedilum sp. (Orchidaceae) and its reversal by blue light

    Energy Technology Data Exchange (ETDEWEB)

    Zeiger, E.; Grivet, C.; Assmann, S.M.; Dietzer, G.F.; Hannegan, M.W.

    1985-02-01

    Leaves from Paphiopedilum sp. (Orchidaceae) having achlorophyllous stomata, show reduced levels of stomatal conductance when irradiated with red light, as compared with either the related, chlorophyllous genus Phragmipedium or with their response to blue light. These reduced levels of stomatal conductance, and the failure of isolated Paphiopedilum stomata to open under red irradiation indicates that the small stomatal response measured in the intact leaf under red light is indirect. The overall low levels of stomatal conductance observed in Paphiopedilum leaves under most growing conditions and their capacity to increase stomatal conductance in response to blue light suggested that growth and carbon gain in Paphiopedilum could be enhanced in a blue light-enriched environment. To test that hypothesis, plants of Paphiopedilum acmodontum were grown in controlled growth chambers under daylight fluorescent light, with or without blue light supplementation. Blue light enrichment resulted in significantly higher growth rates over a 3 to 4 week growing period, with all evidence indicating that the blue light effect was a stomatal response. Manipulations of stomatal properties aimed at long-term carbon gains could have agronomic applications.

  5. An Abscisic Acid-Independent Oxylipin Pathway Controls Stomatal Closure and Immune Defense in Arabidopsis

    Science.gov (United States)

    Mondy, Samuel; Tranchimand, Sylvain; Rumeau, Dominique; Boudsocq, Marie; Garcia, Ana Victoria; Douki, Thierry; Bigeard, Jean; Laurière, Christiane; Chevalier, Anne; Castresana, Carmen; Hirt, Heribert

    2013-01-01

    Plant stomata function in innate immunity against bacterial invasion and abscisic acid (ABA) has been suggested to regulate this process. Using genetic, biochemical, and pharmacological approaches, we demonstrate that (i) the Arabidopsis thaliana nine-specific-lipoxygenase encoding gene, LOX1, which is expressed in guard cells, is required to trigger stomatal closure in response to both bacteria and the pathogen-associated molecular pattern flagellin peptide flg22; (ii) LOX1 participates in stomatal defense; (iii) polyunsaturated fatty acids, the LOX substrates, trigger stomatal closure; (iv) the LOX products, fatty acid hydroperoxides, or reactive electrophile oxylipins induce stomatal closure; and (v) the flg22-mediated stomatal closure is conveyed by both LOX1 and the mitogen-activated protein kinases MPK3 and MPK6 and involves salicylic acid whereas the ABA-induced process depends on the protein kinases OST1, MPK9, or MPK12. Finally, we show that the oxylipin and the ABA pathways converge at the level of the anion channel SLAC1 to regulate stomatal closure. Collectively, our results demonstrate that early biotic signaling in guard cells is an ABA-independent process revealing a novel function of LOX1-dependent stomatal pathway in plant immunity. PMID:23526882

  6. The Stomatal Ontogeny and Structure of the Liassic Pteridosperm Sagenopteris (Caytoniales) from Hungary.

    Science.gov (United States)

    Barbacka; Bóka

    2000-01-01

    Stomatal ontogeny is often inferred but rarely documented for extinct fossil plants because it requires observations from young leaves that are rarely preserved as fossils. The discovery of several very young leaves of the Jurassic plant Sagenopteris (Caytoniales) in the Mecsek Mountains (southern Hungary) in a good state of preservation provides the opportunity for studying the stomatal ontogenesis of this genus. The specimens show perigenous anomocytic stomata. This feature confirms the evolutionarily high position of Sagenopteris among fossil gymnosperms and supports the opinion that the ancestors of angiosperms and some groups of pteridosperms might be closely related. Such clear examples of stomatal development have not previously been documented for fossil material.

  7. A dynamic hydro-mechanical and biochemical model of stomatal conductance for C4 photosynthesis

    OpenAIRE

    Bellasio, C.; Quirk, J.; Buckley, T.N.; Beerling, D.J.

    2017-01-01

    C4 plants are major grain (maize, sorghum), sugar (sugarcane) and biofuel (Miscanthus) producers,\\ud and contribute ~20% to global productivity. Plants lose water through stomatal pores in order to\\ud acquire CO2 (assimilation, A), and control their carbon-for-water balance by regulating stomatal\\ud conductance (gS). The ability to mechanistically predict gS and A in response to atmospheric CO2,\\ud water availability and time is critical for simulating stomatal control of plant-atmospheric ca...

  8. A comparison of two stomatal conductance models for ozone flux modelling using data from two Brassica species

    Energy Technology Data Exchange (ETDEWEB)

    Op de Beeck, M., E-mail: maarten.opdebeeck@ua.ac.b [Research Group of Plant and Vegetation Ecology, University of Antwerp, Campus Drie Eiken, Department of Biology, Universiteitsplein 1, 2160 Wilrijk (Belgium); De Bock, M., E-mail: maarten.debock@ua.ac.b [Research Group of Molecular Plant Physiology and Biotechnology, University of Antwerp, Campus Groenenborger, Department of Biology, Groenenborgerlaan 171, 2020 Antwerpen (Belgium); Vandermeiren, K., E-mail: kavan@var.fgov.b [Veterinary and Agrochemical Research Centre (VAR), Leuvensesteenweg 17, 3080 Tervuren (Belgium); Temmerman, L. de, E-mail: ludet@var.fgov.b [Veterinary and Agrochemical Research Centre (VAR), Leuvensesteenweg 17, 3080 Tervuren (Belgium); Ceulemans, R., E-mail: reinhart.ceulemans@ua.ac.b [Research Group of Plant and Vegetation Ecology, University of Antwerp, Campus Drie Eiken, Department of Biology, Universiteitsplein 1, 2160 Wilrijk (Belgium)

    2010-10-15

    In this study we tested and compared a multiplicative stomatal model and a coupled semi-empirical stomatal-photosynthesis model in their ability to predict stomatal conductance to ozone (g{sub st}) using leaf-level data from oilseed rape (Brassica napus L.) and broccoli (Brassica oleracea L. var. italica Plenck). For oilseed rape, the multiplicative model and the coupled model were able to explain 72% and 73% of the observed g{sub st} variance, respectively. For broccoli, the models were able to explain 53% and 51% of the observed g{sub st} variance, respectively. These results support the coupled semi-empirical stomatal-photosynthesis model as a valid alternative to the multiplicative stomatal model for O{sub 3} flux modelling, in terms of predictive performance. - A multiplicative stomatal model and a coupled semi-empirical stomatal-photosynthesis model performed equally well when tested against leaf-level data for oilseed rape and broccoli.

  9. Can Sap Flow Help Us to Better Understand Transpiration Patterns in Landscapes?

    Science.gov (United States)

    Hassler, S. K.; Weiler, M.; Blume, T.

    2017-12-01

    Transpiration is a key process in the hydrological cycle and a sound understanding and quantification of transpiration and its spatial variability is essential for management decisions and for improving the parameterisation of hydrological and soil-vegetation-atmosphere transfer models. At the tree scale, transpiration is commonly estimated by measuring sap flow. Besides evaporative demand and water availability, tree-specific characteristics such as species, size or social status, stand-specific characteristics such as basal area or stand density and site-specific characteristics such as geology, slope position or aspect control sap flow of individual trees. However, little is known about the relative importance or the dynamic interplay of these controls. We studied these influences with multiple linear regression models to explain the variability of sap velocity measurements in 61 beech and oak trees, located at 24 sites spread over a 290 km²-catchment in Luxembourg. For each of 132 consecutive days of the growing season of 2014 we applied linear models to the daily spatial pattern of sap velocity and determined the importance of the different predictors. By upscaling sap velocities to the tree level with the help of species-dependent empirical estimates for sapwood area we also examined patterns of sap flow as a more direct representation of transpiration. Results indicate that a combination of mainly tree- and site-specific factors controls sap velocity patterns in this landscape, namely tree species, tree diameter, geology and aspect. For sap flow, the site-specific predictors provided the largest contribution to the explained variance, however, in contrast to the sap velocity analysis, geology was more important than aspect. Spatial variability of atmospheric demand and soil moisture explained only a small fraction of the variance. However, the temporal dynamics of the explanatory power of the tree-specific characteristics, especially species, were

  10. Tree-, stand- and site-specific controls on landscape-scale patterns of transpiration

    Science.gov (United States)

    Kathrin Hassler, Sibylle; Weiler, Markus; Blume, Theresa

    2018-01-01

    Transpiration is a key process in the hydrological cycle, and a sound understanding and quantification of transpiration and its spatial variability is essential for management decisions as well as for improving the parameterisation and evaluation of hydrological and soil-vegetation-atmosphere transfer models. For individual trees, transpiration is commonly estimated by measuring sap flow. Besides evaporative demand and water availability, tree-specific characteristics such as species, size or social status control sap flow amounts of individual trees. Within forest stands, properties such as species composition, basal area or stand density additionally affect sap flow, for example via competition mechanisms. Finally, sap flow patterns might also be influenced by landscape-scale characteristics such as geology and soils, slope position or aspect because they affect water and energy availability; however, little is known about the dynamic interplay of these controls.We studied the relative importance of various tree-, stand- and site-specific characteristics with multiple linear regression models to explain the variability of sap velocity measurements in 61 beech and oak trees, located at 24 sites across a 290 km2 catchment in Luxembourg. For each of 132 consecutive days of the growing season of 2014 we modelled the daily sap velocity and derived sap flow patterns of these 61 trees, and we determined the importance of the different controls.Results indicate that a combination of mainly tree- and site-specific factors controls sap velocity patterns in the landscape, namely tree species, tree diameter, geology and aspect. For sap flow we included only the stand- and site-specific predictors in the models to ensure variable independence. Of those, geology and aspect were most important. Compared to these predictors, spatial variability of atmospheric demand and soil moisture explains only a small fraction of the variability in the daily datasets. However, the temporal

  11. The stomatal CO2 proxy does not saturate at high atmospheric CO2 concentrations: evidence from stomatal index responses of Araucariaceae conifers.

    Science.gov (United States)

    Haworth, Matthew; Elliott-Kingston, Caroline; McElwain, Jennifer C

    2011-09-01

    The inverse relationship between the number of stomata on a leaf surface and the atmospheric carbon dioxide concentration ([CO(2)]) in which the leaf developed allows plants to optimise water-use efficiency (WUE), but it also permits the use of fossil plants as proxies of palaeoatmospheric [CO(2)]. The ancient conifer family Araucariaceae is often represented in fossil floras and may act as a suitable proxy of palaeo-[CO(2)], yet little is known regarding the stomatal index (SI) responses of extant Araucariaceae to [CO(2)]. Four Araucaria species (Araucaria columnaris, A. heterophylla, A. angustifolia and A. bidwillii) and Agathis australis displayed no significant relationship in SI to [CO(2)] below current ambient levels (~380 ppm). However, representatives of the three extant genera within the Araucariaceae (A. bidwillii, A. australis and Wollemia nobilis) all exhibited significant reductions in SI when grown in atmospheres of elevated [CO(2)] (1,500 ppm). Stomatal conductance was reduced and WUE increased when grown under elevated [CO(2)]. Stomatal pore length did not increase alongside reduced stomatal density (SD) and SI in the three araucariacean conifers when grown at elevated [CO(2)]. These pronounced SD and SI reductions occur at higher [CO(2)] levels than in other species with more recent evolutionary origins, and may reflect an evolutionary legacy of the Araucariaceae in the high [CO(2)] world of the Mesozoic Era. Araucariacean conifers may therefore be suitable stomatal proxies of palaeo-[CO(2)] during periods of "greenhouse" climates and high [CO(2)] in the Earth's history.

  12. Consistent allometric scaling of stomatal sizes and densities across taxonomic ranks and geologic time

    Science.gov (United States)

    de Boer, H. J.; Price, C. A.; Wagner-Cremer, F.; Dekker, S. C.; Veneklaas, E. J.

    2013-12-01

    Stomatal pores on plants leaves are an important link in the chain of processes that determine biosphere fluxes of water and carbon. Stomatal density (i.e. the number of stomata per area) and the size of the stomatal pore at maximum aperture are particularly relevant traits in this context because they determine the theoretical maximum diffusive stomatal conductance (gsmax) and thereby set an upper limit for leaf gas exchange. Observations on (sub)fossil leaves revealed that changes in stomatal densities are anti-correlated with changes in stomatal sizes at developmental and evolutionary timescales. Moreover, this anti-correlation appears consistently within single species, across multiple species in the extant plant community and at evolutionary time scales. The consistency of the relation between stomatal densities and sizes suggests that common mechanisms constrain the adaptation of these traits across the plant community. In an attempt to identify such potential generic constraints, we investigated the allometry between stomatal densities and sizes in the extant plant community and across geological time. As the size of the stomatal pore at maximum aperture is typically derived from the length of the stomatal pore, we considered the allometric scaling of pore length (lp) with stomatal density (Ds) as the power law: lp = k . Dsa in which k is a normalization constant and the exponent a is the slope of the scaling relation. Our null-hypothesis predicts that stomatal density and pore length scale along a constant slope of -1/2 based on a scale-invariant relation between pore length and the distance between neighboring pores. Our alternative hypothesis predicts a constant slope of -1 based on the idea that stomatal density and pore length scale along an invariant gsmax. To explore these scaling hypotheses in the extant plant community we compiled a dataset of combined observations of stomatal density and pore length on 111 species from published literature and new

  13. Model-assisted analysis of spatial and temporal variations in fruit temperature and transpiration highlighting the role of fruit development.

    Directory of Open Access Journals (Sweden)

    Thibault Nordey

    Full Text Available Fruit physiology is strongly affected by both fruit temperature and water losses through transpiration. Fruit temperature and its transpiration vary with environmental factors and fruit characteristics. In line with previous studies, measurements of physical and thermal fruit properties were found to significantly vary between fruit tissues and maturity stages. To study the impact of these variations on fruit temperature and transpiration, a modelling approach was used. A physical model was developed to predict the spatial and temporal variations of fruit temperature and transpiration according to the spatial and temporal variations of environmental factors and thermal and physical fruit properties. Model predictions compared well to temperature measurements on mango fruits, making it possible to accurately simulate the daily temperature variations of the sunny and shaded sides of fruits. Model simulations indicated that fruit development induced an increase in both the temperature gradient within the fruit and fruit water losses, mainly due to fruit expansion. However, the evolution of fruit characteristics has only a very slight impact on the average temperature and the transpiration per surface unit. The importance of temperature and transpiration gradients highlighted in this study made it necessary to take spatial and temporal variations of environmental factors and fruit characteristics into account to model fruit physiology.

  14. Transpiration and biomass production of the bioenergy crop Giant Knotweed Igniscum under various supplies of water and nutrients

    Directory of Open Access Journals (Sweden)

    Mantovani Dario

    2014-12-01

    Full Text Available Soil water availability, nutrient supply and climatic conditions are key factors for plant production. For a sustainable integration of bioenergy plants into agricultural systems, detailed studies on their water uses and growth performances are needed. The new bioenergy plant Igniscum Candy is a cultivar of the Sakhalin Knotweed (Fallopia sachalinensis, which is characterized by a high annual biomass production. For the determination of transpiration-yield relations at the whole plant level we used wicked lysimeters at multiple irrigation levels associated with the soil water availability (25, 35, 70, 100% and nitrogen fertilization (0, 50, 100, 150 kg N ha-1. Leaf transpiration and net photosynthesis were determined with a portable minicuvette system. The maximum mean transpiration rate was 10.6 mmol m-2 s-1 for well-watered plants, while the mean net photosynthesis was 9.1 μmol m-2 s-1. The cumulative transpiration of the plants during the growing seasons varied between 49 l (drought stressed and 141 l (well-watered per plant. The calculated transpiration coefficient for Fallopia over all of the treatments applied was 485.6 l kg-1. The transpiration-yield relation of Igniscum is comparable to rye and barley. Its growth performance making Fallopia a potentially good second generation bioenergy crop.

  15. Long-term mannitol-induced osmotic stress leads to stomatal ...

    African Journals Online (AJOL)

    Long-term mannitol-induced osmotic stress leads to stomatal closure, carbohydrate accumulation and changes in leaf elasticity in Phaselous vulgaris leaves. S Sassi, S Aydi, K Hessini, EM Gonzalez, C Arrese-Igor, C Abdelly ...

  16. Testing of models of stomatal ozone fluxes with field measurements in a mixed Mediterranean forest

    Czech Academy of Sciences Publication Activity Database

    Fares, S.; Matteucci, G.; Mugnozza, S.; Morani, A.; Calfapietra, Carlo; Salvatori, E.; Fusaro, L.; Manes, F.; Loreto, F.

    2013-01-01

    Roč. 67, MAR (2013), s. 242-251 ISSN 1352-2310 Institutional support: RVO:67179843 Keywords : Ozone fluxes * Stomatal conductance models * GPP * Mediterranean forest Subject RIV: EH - Ecology, Behaviour Impact factor: 3.062, year: 2013

  17. Breaking the silence: three bHLH proteins direct cell-fate decisions during stomatal development.

    Science.gov (United States)

    Pillitteri, Lynn Jo; Torii, Keiko U

    2007-09-01

    Stomata are microscopic pores on the surface of land plants used for gas and water vapor exchange. A pair of highly specialized guard cells surround the pore and adjust pore size. Studies in Arabidopsis have revealed that cell-cell communication is essential to coordinate the asymmetric cell divisions required for proper stomatal patterning. Initial research in this area identified signaling molecules that negatively regulate stomatal differentiation. However, genes promoting cell-fate transition leading to mature guard cells remained elusive. Now, three closely related basic helix-loop-helix (bHLH) proteins, SPEECHLESS, MUTE and FAMA have been identified as positive regulators that direct three consecutive cell-fate decisions during stomatal development. The identification of these genes opens a new direction to investigate the evolution of stomatal development and the conserved functions of bHLH proteins in cell type differentiation adopted by plants and animals.

  18. Developmental priming of stomatal sensitivity to abscisic acid by leaf microclimate.

    Science.gov (United States)

    Pantin, Florent; Renaud, Jeanne; Barbier, François; Vavasseur, Alain; Le Thiec, Didier; Rose, Christophe; Bariac, Thierry; Casson, Stuart; McLachlan, Deirdre H; Hetherington, Alistair M; Muller, Bertrand; Simonneau, Thierry

    2013-09-23

    Plant water loss and CO2 uptake are controlled by valve-like structures on the leaf surface known as stomata. Stomatal aperture is regulated by hormonal and environmental signals. We show here that stomatal sensitivity to the drought hormone abscisic acid (ABA) is acquired during leaf development by exposure to an increasingly dryer atmosphere in the rosette plant Arabidopsis. Young leaves, which develop in the center of the rosette, do not close in response to ABA. As the leaves increase in size, they are naturally exposed to increasingly dry air as a consequence of the spatial arrangement of the leaves, and this triggers the acquisition of ABA sensitivity. Interestingly, stomatal ABA sensitivity in young leaves is rapidly restored upon water stress. These findings shed new light on how plant architecture and stomatal physiology have coevolved to optimize carbon gain against water loss in stressing environments. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Serum cytokine profile and clinicopathological findings in oral lichen planus, oral lichenoid lesions and stomatitis

    DEFF Research Database (Denmark)

    Larsen, Kristine Røn; Johansen, Jeanne Duus; Reibel, Jesper

    2017-01-01

    The objective of this study was to examine if clinical and histopathological variables in patients with oral lichen planus (OLP), oral lichenoid lesions (OLL), and generalized stomatitis display different cytokine profiles and if concomitant contact allergy influences this profile. Forty...

  20. Leaf temperature and transpiration of rice plants in relation to short-wave radiation and wind speed

    International Nuclear Information System (INIS)

    Ito, D.; Haseba, T.

    1984-01-01

    Leaf temperature and transpiration amount of rice plants were measured in a steady environment in a laboratory and in field situations. The plants set in Wagner pots were used. Experiments were carried out at the tillering and booting stages, and on the date of maturity. Measured leaf temperatures and transpiration rates were analyzed in connection with incident short-wave radiation on a leaf and wind speed measured simultaneously.Instantaneous supplying and turning-off of steady artificial light caused cyclic changes in leaf temperature and transpiration. Leaf temperature dropped in feeble illumination compared with the steady temperature in the preceeding dark.On the date of maturity, a rice plant leaf was warmer than the air, even in feeble light. Then, the leaf-air temperature difference and transpiration rate showed approximately linear increases with short-wave radiation intensity. On the same date, an increase in wind speed produced a decrease in leaf-air temperature difference, i.e., leaf temperature dropped, and an increase in transpiration rate. The rates of both changes in leaf temperature and transpiration rate were fairly large in a range of wind speed below about 1m/s.For rice plants growing favorably from the tillering stage through the booting stage, the leaves were considerably cooler than the air, even in an intense light and/or solar radiation. The leaf temperature showed the lowest value at short-wave radiations between 0.15 and 0.20ly/min, at above which the leaf temperature rised with an increase in short-wave radiation until it approached the air temperature. Transpiration rate of rice plants increased rapidly with an increase in short-wave radiation ranging below 0.2 or 0.3ly/min, at above which the increase in transpiration rate slowed.The relationships between leaf temperature and/or transpiration rate and wind speed and/or incident short-wave radiation (solar radiation) which were obtained experimentally, supported the relationships

  1. Carbonic anhydrases, EPF2 and a novel protease mediate CO2 control of stomatal development

    Science.gov (United States)

    Engineer, Cawas B.; Ghassemian, Majid; Anderson, Jeffrey C.; Peck, Scott C.; Hu, Honghong; Schroeder, Julian I.

    2014-09-01

    Environmental stimuli, including elevated carbon dioxide levels, regulate stomatal development; however, the key mechanisms mediating the perception and relay of the CO2 signal to the stomatal development machinery remain elusive. To adapt CO2 intake to water loss, plants regulate the development of stomatal gas exchange pores in the aerial epidermis. A diverse range of plant species show a decrease in stomatal density in response to the continuing rise in atmospheric CO2 (ref. 4). To date, one mutant that exhibits deregulation of this CO2-controlled stomatal development response, hic (which is defective in cell-wall wax biosynthesis, ref. 5), has been identified. Here we show that recently isolated Arabidopsis thaliana β-carbonic anhydrase double mutants (ca1 ca4) exhibit an inversion in their response to elevated CO2, showing increased stomatal development at elevated CO2 levels. We characterized the mechanisms mediating this response and identified an extracellular signalling pathway involved in the regulation of CO2-controlled stomatal development by carbonic anhydrases. RNA-seq analyses of transcripts show that the extracellular pro-peptide-encoding gene EPIDERMAL PATTERNING FACTOR 2 (EPF2), but not EPF1 (ref. 9), is induced in wild-type leaves but not in ca1 ca4 mutant leaves at elevated CO2 levels. Moreover, EPF2 is essential for CO2 control of stomatal development. Using cell-wall proteomic analyses and CO2-dependent transcriptomic analyses, we identified a novel CO2-induced extracellular protease, CRSP (CO2 RESPONSE SECRETED PROTEASE), as a mediator of CO2-controlled stomatal development. Our results identify mechanisms and genes that function in the repression of stomatal development in leaves during atmospheric CO2 elevation, including the carbonic-anhydrase-encoding genes CA1 and CA4 and the secreted protease CRSP, which cleaves the pro-peptide EPF2, in turn repressing stomatal development. Elucidation of these mechanisms advances the understanding of

  2. Electrical signaling, stomatal conductance, ABA and Ethylene content in avocado trees in response to root hypoxia

    OpenAIRE

    Gil, Pilar M; Gurovich, Luis; Schaffer, Bruce; García, Nicolás; Iturriaga, Rodrigo

    2009-01-01

    Avocado (Persea americana Mill.) trees are among the most sensitive of fruit tree species to root hypoxia as a result of flooded or poorly drained soil. Similar to drought stress, an early physiological response to root hypoxia in avocado is a reduction of stomatal conductance. It has been previously determined in avocado trees that an extracellular electrical signal between the base of stem and leaves is produced and related to reductions in stomatal conductance in response to drought stress...

  3. Fern Stomatal Responses to ABA and CO2Depend on Species and Growth Conditions.

    Science.gov (United States)

    Hõrak, Hanna; Kollist, Hannes; Merilo, Ebe

    2017-06-01

    Changing atmospheric CO 2 levels, climate, and air humidity affect plant gas exchange that is controlled by stomata, small pores on plant leaves and stems formed by guard cells. Evolution has shaped the morphology and regulatory mechanisms governing stomatal movements to correspond to the needs of various land plant groups over the past 400 million years. Stomata close in response to the plant hormone abscisic acid (ABA), elevated CO 2 concentration, and reduced air humidity. Whether the active regulatory mechanisms that control stomatal closure in response to these stimuli are present already in mosses, the oldest plant group with stomata, or were acquired more recently in angiosperms remains controversial. It has been suggested that the stomata of the basal vascular plants, such as ferns and lycophytes, close solely hydropassively. On the other hand, active stomatal closure in response to ABA and CO 2 was found in several moss, lycophyte, and fern species. Here, we show that the stomata of two temperate fern species respond to ABA and CO 2 and that an active mechanism of stomatal regulation in response to reduced air humidity is present in some ferns. Importantly, fern stomatal responses depend on growth conditions. The data indicate that the stomatal behavior of ferns is more complex than anticipated before, and active stomatal regulation is present in some ferns and has possibly been lost in others. Further analysis that takes into account fern species, life history, evolutionary age, and growth conditions is required to gain insight into the evolution of land plant stomatal responses. © 2017 American Society of Plant Biologists. All Rights Reserved.

  4. Évaluation des caractéristiques des stomates chez le palmier à huile ...

    African Journals Online (AJOL)

    SARAH

    31 août 2016 ... stomates chez le palmier à huile normal diploïde afin d'appliquer dans le futur les méthodes de la. Biotechnologie. Les objectifs spécifiques portent sur l'évaluation de la densité, de la longueur et de la largeur des stomates des feuilles de palmier à huile en fonction des variétés, de l'âge de la plante et des.

  5. RESIDUAL RISK ASSESSMENTS - RESIDUAL RISK ...

    Science.gov (United States)

    This source category previously subjected to a technology-based standard will be examined to determine if health or ecological risks are significant enough to warrant further regulation for Coke Ovens. These assesments utilize existing models and data bases to examine the multi-media and multi-pollutant impacts of air toxics emissions on human health and the environment. Details on the assessment process and methodologies can be found in EPA's Residual Risk Report to Congress issued in March of 1999 (see web site). To assess the health risks imposed by air toxics emissions from Coke Ovens to determine if control technology standards previously established are adequately protecting public health.

  6. The Pseudomonas syringae type III effector HopF2 suppresses Arabidopsis stomatal immunity.

    Directory of Open Access Journals (Sweden)

    Brenden Hurley

    Full Text Available Pseudomonas syringae subverts plant immune signalling through injection of type III secreted effectors (T3SE into host cells. The T3SE HopF2 can disable Arabidopsis immunity through Its ADP-ribosyltransferase activity. Proteomic analysis of HopF2 interacting proteins identified a protein complex containing ATPases required for regulating stomatal aperture, suggesting HopF2 may manipulate stomatal immunity. Here we report HopF2 can inhibit stomatal immunity independent of its ADP-ribosyltransferase activity. Transgenic expression of HopF2 in Arabidopsis inhibits stomatal closing in response to P. syringae and increases the virulence of surface inoculated P. syringae. Further, transgenic expression of HopF2 inhibits flg22 induced reactive oxygen species production. Intriguingly, ADP-ribosyltransferase activity is dispensable for inhibiting stomatal immunity and flg22 induced reactive oxygen species. Together, this implies HopF2 may be a bifunctional T3SE with ADP-ribosyltransferase activity required for inhibiting apoplastic immunity and an independent function required to inhibit stomatal immunity.

  7. Light and growth form interact to shape stomatal ratio among British angiosperms.

    Science.gov (United States)

    Muir, Christopher D

    2018-04-01

    In most plants, stomata are located only on the abaxial leaf surface (hypostomy), but many plants have stomata on both surfaces (amphistomy). High light and herbaceous growth form have been hypothesized to favor amphistomy, but these hypotheses have not been rigorously tested together using phylogenetic comparative methods. I leveraged a large dataset including stomatal ratio, Ellenberg light indicator value, growth form and phylogenetic relationships for 372 species of British angiosperms. I used phylogenetic comparative methods to test how light and/or growth form influence stomatal ratio and density. High light and herbaceous growth form are correlated with amphistomy, as predicted, but they also interact; the effect of light is pronounced in therophytes (annuals) and perennial herbs, but muted in phanerophytes (shrubs and trees). Furthermore, amphistomy and stomatal density evolve together in response to light. Comparative analyses of British angiosperms reveal two major insights. First, light and growth form interact to shape stomatal ratio; amphistomy is common under high light, but mostly for herbs. Second, coordinated evolution of adaxial stomatal density and light tolerance indicates that amphistomy helps to optimally balance light acquisition with gas exchange. Stomatal ratio may have potential as a functional trait for paleoecology and crop improvement. © 2018 The Author. New Phytologist © 2018 New Phytologist Trust.

  8. What are the evolutionary origins of stomatal responses to abscisic acid in land plants?

    Science.gov (United States)

    Sussmilch, Frances C; Brodribb, Timothy J; McAdam, Scott A M

    2017-04-01

    The evolution of active stomatal closure in response to leaf water deficit, mediated by the hormone abscisic acid (ABA), has been the subject of recent debate. Two different models for the timing of the evolution of this response recur in the literature. A single-step model for stomatal control suggests that stomata evolved active, ABA-mediated control of stomatal aperture, when these structures first appeared, prior to the divergence of bryophyte and vascular plant lineages. In contrast, a gradualistic model for stomatal control proposes that the most basal vascular plant stomata responded passively to changes in leaf water status. This model suggests that active ABA-driven mechanisms for stomatal responses to water status instead evolved after the divergence of seed plants, culminating in the complex, ABA-mediated responses observed in modern angiosperms. Here we review the findings that form the basis for these two models, including recent work that provides critical molecular insights into resolving this intriguing debate, and find strong evidence to support a gradualistic model for stomatal evolution. © 2017 Institute of Botany, Chinese Academy of Sciences.

  9. A first look at the SAPFLUXNET database: global patterns in whole-plant transpiration and implications for ecohydrological research

    Science.gov (United States)

    Poyatos, R.; Granda, V.; Mencuccini, M.; Flo, V.; Oren, R.; Molowny-Horas, R.; Katul, G. G.; Mahecha, M. D.; Steppe, K.; Cabon, A.; De Cáceres, M.; Martínez-Vilalta, J.

    2017-12-01

    Plant transpiration is the fundamental process linking water and vegetation and it is therefore a central topic in ecohydrological research. Globally, plants display a huge variety of coordinated adjustments in their physiology and structure to regulate transpiration in response to fluctuations of water demand and supply at multiple temporal scales. Sap flow measured in plant stems reveals the temporal patterns of these responses but sap flow data have remained fragmentary and generally unavailable for syntheses of regional to global scope. Here we present the first global database of sap flow measurements from individual plants (SAPFLUXNET, http://sapfluxnet.creaf.cat/), which has been compiled from > 150 datasets contributed by researchers worldwide. Received datasets were harmonised and conveniently stored in custom-designed R objects holding sap flow and environmental data time series, together with several ancillary metadata, enabling data access for synthesis activities. SAPFLUXNET covers most vegetated biomes and holds data for > 1500 individual plants, mostly trees, belonging to >100 species and > 50 genera. We retrieved water use traits indicative of maximum transpiration rates and of transpiration sensitivity to vapour pressure deficit using quantile regression approaches and moving window analyses. Global patterns of these water use traits were then analysed as a function of climate, plant functional type and stand characteristics. For example, maximum transpiration rates at a given plant diameter or sapwood area tended to be higher for Angiosperms compared to Gymnosperms, but this relationships converged to a more similar scaling between transpiration and leaf area across these groups. SAPFLUXNET is also a valuable tool to evaluate water balance components in ecosystem models. We combined SAPFLUXNET data with the MEDFATE model (https://cran.r-project.org/web/packages/medfate/index.html) to validate an ecohydrological optimisation approach to retrieve

  10. Oncotargeting by Vesicular Stomatitis Virus (VSV: Advances in Cancer Therapy

    Directory of Open Access Journals (Sweden)

    Suman Bishnoi

    2018-02-01

    Full Text Available Modern oncotherapy approaches are based on inducing controlled apoptosis in tumor cells. Although a number of apoptosis-induction approaches are available, site-specific delivery of therapeutic agents still remain the biggest hurdle in achieving the desired cancer treatment benefit. Additionally, systemic treatment-induced toxicity remains a major limiting factor in chemotherapy. To specifically address drug-accessibility and chemotherapy side effects, oncolytic virotherapy (OV has emerged as a novel cancer treatment alternative. In OV, recombinant viruses with higher replication capacity and stronger lytic properties are being considered for tumor cell-targeting and subsequent cell lysing. Successful application of OVs lies in achieving strict tumor-specific tropism called oncotropism, which is contingent upon the biophysical interactions of tumor cell surface receptors with viral receptors and subsequent replication of oncolytic viruses in cancer cells. In this direction, few viral vector platforms have been developed and some of these have entered pre-clinical/clinical trials. Among these, the Vesicular stomatitis virus (VSV-based platform shows high promise, as it is not pathogenic to humans. Further, modern molecular biology techniques such as reverse genetics tools have favorably advanced this field by creating efficient recombinant VSVs for OV; some have entered into clinical trials. In this review, we discuss the current status of VSV based oncotherapy, challenges, and future perspectives regarding its therapeutic applications in the cancer treatment.

  11. The denture hygiene, denture stomatitis and role of dental hygienist.

    Science.gov (United States)

    Sadig, W

    2010-08-01

    Denture induced stomatitis (DIS) affects a large number of denture wearer patients, particularly elderly people. The purpose of this study was to determine the prevalence of DIS among a sample of denture wearers attending a teaching hospital, in relation to denture hygiene level and method, age, gender, objective and subjective severity of the lesion. A total of 71 denture wearers were systemically interviewed and clinically examined by the same operator of their oral mucosal health and the denture hygiene practice. A questionnaire, including 20 questions was used in this study. The results showed an incidence of DIS in both arches of 62% with no difference between the maxillary and mandibular arches. Denture hygiene within patients was good by 21.1%, of the sample, fair by 43.6% and poor by 35.2%. Another finding proved the incidence of DIS to be higher (Rev-1 + Rev-2) in elderly patients and a significant association was found between the presence of DIS and denture hygiene habits and sleeping with dentures (P responsibility by routinely providing post-placement denture hygiene instructions to educate and motivate the patient.

  12. Uncaria tomentosa Gel against Denture Stomatitis: Clinical Report.

    Science.gov (United States)

    Tay, Lidia Y; Dos Santos, Fabio A; Jorge, Janaina H

    2015-02-09

    The objective of this study is to report the clinical use of 2% Uncaria tomentosa gel against denture stomatitis (DS) as an alternative treatment. The patient was a 65-year-old, denture-wearing woman. At the clinical examination, her palate showed hyperplasic and erythematous mucosa indicating DS type II. DS is a chronic oral disease that affects denture wearers. It occurs as an inflammatory reaction in denture-wearing patients under maxillary prostheses. Candida albicans has been reported as the principal etiological agent. An alternative treatment, the topical application of a gel of 2% U. tomentosa three times a day for 1 week was given to the patient. After 1 week of this treatment, she had significantly reduced signs of the disease. Despite the existence of a great number of antifungal agents, treatment failure is observed frequently. Phytotherapy is becoming more popular worldwide. Currently, the most promising medicinal Amazonian herb is U. tomentosa (Willd.) DC., known as Cat's Claw. Studies of the chemical and pharmacological properties of this medicinal plant have allowed researchers to develop indications for its use. This report demonstrates the effectiveness of U. tomentosa against DS. © 2015 by the American College of Prosthodontists.

  13. Diurnal photosynthesis and stomatal resistance in field-grown soybeans

    International Nuclear Information System (INIS)

    Miller, J.E.; Muller, R.N.; Seegers, P.

    1976-01-01

    The process of photosynthesis in green plants is the major determinant of crop yield. Although the effects of air pollutants, such as sulfur dioxide, on photosynthesis has been studied, many unsolved questions remain. This is especially true with regard to reduction of photosynthetic rate under conditions of chronic exposure causing little or no visible injury. It was the purpose of these studies to develop techniques suitable for measuring photosynthetic rates of field-grown plants without dramatically altering the microenvironment of the plants. Gross photosynthetic rates of soybeans (Glycine max. cv. Wayne) in the field were measured by exposing a small section of representative leaves for 30 seconds to 14 CO 2 in a normal atmospheric mixture by a technique similar to that of Incoll and Wright. A 1-cm 2 section of the area exposed to 14 CO 2 is punched from the leaf and processed for liquid scintillation counting. Since the treatment period is of such short duration, there is little photorespiratory loss of 14 CO 2 , and thus, the amount of 14 C fixed in the leaf can be related to the gross photosynthetic rate. Other parameters measured during the course of these experiments were stomatal resistance, light intensity, leaf water potential, and air temperature

  14. ELISA test for p63 antibodies in chronic ulcerative stomatitis.

    Science.gov (United States)

    Solomon, L W; Stark, P C; Winter, L; Kumar, V; Sinha, S

    2010-03-01

    To develop a novel test for chronic ulcerative stomatitis (CUS), a chronic immunologically mediated condition that produces oral ulcerations. Current diagnostic methods require expensive and technically demanding in situ immunofluorescence (IF) studies. An Enzyme-Linked ImmunoSorbent Assay (ELISA) was prepared and tested with serum samples from patients with CUS and negative controls. The N-terminal portion of the CUS autoantigen, DeltaNp63alpha, was produced as a purified recombinant protein and used to coat ELISA plates. Sera from 25 patients with CUS and 16 negative controls were analyzed for reactive antibodies. The optimal cut-offs for positive and negative samples were determined. The optimal cut-off of 0.236 resulted in a sensitivity and specificity of the ELISA of 0.80 and 0.75, respectively (exact 95% confidence intervals, P-value of <0.001). The ELISA developed in this study provides a novel and reliable diagnostic assessment to distinguish CUS from other oral ulcerative diseases. Immunoassay will allow the true incidence and prevalence of CUS to be determined in future studies. When combined with clinical correlations, the ELISA results will facilitate the evaluation of the prognostic utility of antibody titers and allow correlation with treatment responses in individual CUS cases.

  15. Making pore choices: repeated regime shifts in stomatal ratio.

    Science.gov (United States)

    Muir, Christopher D

    2015-08-22

    Ecologically important traits do not evolve without limits. Instead, evolution is constrained by the set of available and viable phenotypes. In particular, natural selection may only favour a narrow range of adaptive optima constrained within selective regimes. Here, I integrate data with theory to test whether selection explains phenotypic constraint. A global database of 599 plant species from 94 families shows that stomatal ratio, a trait affecting photosynthesis and defence against pathogens, is highly constrained. Most plants have their stomata on the lower leaf surface (hypostomy), but species with half their stomata on each surface (amphistomy) form a distinct mode in the trait distribution. A model based on a trade-off between maximizing photosynthesis and a fitness cost of upper stomata predicts a limited number of adaptive solutions, leading to a multimodal trait distribution. Phylogenetic comparisons show that amphistomy is the most common among fast-growing species, supporting the view that CO2 diffusion is under strong selection. These results indicate that selective optima stay within a relatively stable set of selective regimes over macroevolutionary time. © 2015 The Author(s).

  16. A photosynthesis-based two-leaf canopy stomatal ...

    Science.gov (United States)

    A coupled photosynthesis-stomatal conductance model with single-layer sunlit and shaded leaf canopy scaling is implemented and evaluated in a diagnostic box model with the Pleim-Xiu land surface model (PX LSM) and ozone deposition model components taken directly from the meteorology and air quality modeling system—WRF/CMAQ (Weather Research and Forecast model and Community Multiscale Air Quality model). The photosynthesis-based model for PX LSM (PX PSN) is evaluated at a FLUXNET site for implementation against different parameterizations and the current PX LSM approach with a simple Jarvis function (PX Jarvis). Latent heat flux (LH) from PX PSN is further evaluated at five FLUXNET sites with different vegetation types and landscape characteristics. Simulated ozone deposition and flux from PX PSN are evaluated at one of the sites with ozone flux measurements. Overall, the PX PSN simulates LH as well as the PX Jarvis approach. The PX PSN, however, shows distinct advantages over the PX Jarvis approach for grassland that likely result from its treatment of C3 and C4 plants for CO2 assimilation. Simulations using Moderate Resolution Imaging Spectroradiometer (MODIS) leaf area index (LAI) rather than LAI measured at each site assess how the model would perform with grid averaged data used in WRF/CMAQ. MODIS LAI estimates degrade model performance at all sites but one site having exceptionally old and tall trees. Ozone deposition velocity and ozone flux along with LH

  17. A review on the oxidative stress in recurrent aphtous stomatitis

    Directory of Open Access Journals (Sweden)

    Mehryari Mahsa

    2015-01-01

    Full Text Available   Background and Aims: The purpose of the present study was to review the studies regarding serological and salivary oxidant / antioxidant status in patients with recurrent aphthous stomatitis (RAS.   Materials and Methods: The literature was searched using key words RAS, Antioxidants, Saliva, Hematinic (s and Hematinic Acid in the last 10 years, particularly the recent 3 years (2010-2013. At total of 37 clinical trials, 18 case-control articles were selected and evaluated; fulfilling the requirements as the RAS patients having at least 3 oral aphthous attack per year. The exclusion criteria included systemic as well as periodontal diseases, iron deficiency associated anemia, medication usage and smoking.   Conclusion: Almost all lipid-peroxidation studies in serum and saliva were manifested by an increase of malondialdehyde (MDA concentration in RAS patients compared with controls. This would indicate the role of reactive oxygen species (ROS in the etiology of the disease. Serum trace elements (Zn, Se were reduced and Cu was increased in RAS patients in comparison with control individuals. A decreased serum superoxide dismutase (SOD and an increased salivary SOD were observed in all RAS patients. Catalase (CAT and uric acid (UA analyses were non-inclusive. Levels of paraoxonase and arylesterase as well as antioxidant vitamins (A, E, C were lower in RAS patients than that of controls.

  18. Clouds homogenize shoot temperatures, transpiration, and photosynthesis within crowns of Abies fraseri (Pursh.) Poiret.

    Science.gov (United States)

    Hernandez-Moreno, J Melissa; Bayeur, Nicole M; Coley, Harold D; Hughes, Nicole M

    2017-03-01

    Multiple studies have examined the effects of clouds on shoot and canopy-level microclimate and physiological processes; none have yet done so on the scale of individual plant crowns. We compared incident photosynthetically active radiation (PAR), leaf temperatures, chlorophyll fluorescence, and photosynthetic gas exchange of shoots in three different spatial locations of Abies fraseri crowns on sunny (clear to partly cloudy) versus overcast days. The field site was a Fraser fir farm (1038 m elevation) in the Appalachian mountains, USA. Ten saplings of the same age class were marked and revisited for all measurements. Sunny conditions corresponded with 5-10× greater sunlight incidence on south-facing outer shoots compared to south-facing inner and north-facing outer shoots, which were shaded and received only indirect (diffuse) sunlight. Differences in spatial distribution of irradiance were mirrored in differences in shoot temperatures, photosynthesis, and transpiration, which were all greater in south-facing outer shoots compared to more shaded crown locations. In contrast, overcast conditions corresponded with more homogeneous sunlight distribution between north and south-facing outer shoots, and similar shoot temperatures, chlorophyll fluorescence (ΦPSII), photosynthesis, and transpiration; these effects were observed in south-facing inner shoots as well, but to a lesser extent. There was no significant difference in conductance between different crown locations on sunny or overcast days, indicating spatial differences in transpiration under sunny conditions were likely driven by leaf temperature differences. We conclude that clouds can affect spatial distribution of sunlight and associated physiological parameters not only within forest communities, but within individual crowns as well.

  19. Potential application of glazed transpired collectors to space heating in cold climates

    International Nuclear Information System (INIS)

    Gao, Lixin; Bai, Hua; Mao, Shufeng

    2014-01-01

    Highlights: • A mathematical model for glazed transpired collectors (GTC) is developed. • Glazing results in optical loss, but it decreases convective heat loss effectively. • Thermal performance of GTC shows considerable improvement on flat-plate collectors. • GTC using recirculated air is applicable to space heating in cold climates. - Abstract: Although unglazed transpired collectors (UTC) succeed in industrial ventilation applications, solar fraction is very low when they are used in space heating in cold climates due to the lower exit air temperature. Considering the potential for glazed transpired collectors (GTC) using recirculated air for space heating applications in cold climates, a mathematical model is developed for predicting the thermal performance of GTC. Simulation results show that although glazing results in optical loss, it could decrease convective heat loss resulted from high crosswind velocities effectively. For a solar radiation of 400 W/m 2 , an ambient temperature of −10 °C, and a suction velocity of 0.01 m/s, the exit air temperature of GTC is higher than that of UTC for crosswind velocities exceeding 3.0 m/s. By comparison with a conventional flat-plate solar air collector operating under the same conditions, the thermal performance of GTC shows a significant improvement. For a five-storey hotel building located in the severe cold climate zone of China, case study shows that the annual solar fraction of the GTC-based solar air heating system is about 20%, which is two times higher than that of the flat-plate collector-based system and nearly nine times higher than that of the UTC-based system respectively. Hence, an enormous amount of energy will be saved with the application of GTC to space heating in cold climates

  20. Transpiration and hydraulic strategies in a piñon-juniper woodland.

    Science.gov (United States)

    West, A G; Hultine, K R; Sperry, J S; Bush, S E; Ehleringer, J R

    2008-06-01

    Anthropogenic climate change is likely to alter the patterns of moisture availability globally. The consequences of these changes on species distributions and ecosystem function are largely unknown, but possibly predictable based on key ecophysiological differences among currently coexisting species. In this study, we examined the environmental and biological controls on transpiration from a piñon-juniper (Pinus edulis-Juniperus osteosperma) woodland in southern Utah, USA. The potential for climate-change-associated shifts in moisture inputs could play a critical role in influencing the relative vulnerabilities of piñons and junipers to drought and affecting management decisions regarding the persistence of this dominant landscape type in the Intermountain West. We aimed to assess the sensitivity of this woodland to seasonal variations in moisture and to mechanistically explain the hydraulic strategies of P. edulis and J. osteosperma through the use of a hydraulic transport model. Transpiration from the woodland was highly sensitive to variations in seasonal moisture inputs. There were two distinct seasonal pulses of transpiration: a reliable spring pulse supplied by winter-derived precipitation, and a highly variable summer pulse supplied by monsoonal precipitation. Transpiration of P. edulis and J. osteosperma was well predicted by a mechanistic hydraulic transport model (R2 = 0.83 and 0.92, respectively). Our hydraulic model indicated that isohydric regulation of water potential in P. edulis minimized xylem cavitation during drought, which facilitated drought recovery (94% of pre-drought water uptake) but came at the cost of cessation of gas exchange for potentially extended periods. In contrast, the anisohydric J. osteosperma was able to maintain gas exchange at lower water potentials than P. edulis but experienced greater cavitation over the drought and showed a lesser degree of post-drought recovery (55% of pre-drought uptake). As a result, these species

  1. An Analysis of Unglazed Transpired Solar Collectors Based on Exergetic Performance Criteria

    OpenAIRE

    Motahar, Sadegh

    2010-01-01

    In this paper, an exergetic performance analysis of unglazed transpired collectors (UTC), as well as an exergetic optimization of a typical UTC is performed. Residual nilpotence and residual solubility of groups

    International Nuclear Information System (INIS)

    Mikhailov, R V

    2005-01-01

    The properties of the residual nilpotence and the residual solubility of groups are studied. The main objects under investigation are the class of residually nilpotent groups such that each central extension of these groups is also residually nilpotent and the class of residually soluble groups such that each Abelian extension of these groups is residually soluble. Various examples of groups not belonging to these classes are constructed by homological methods and methods of the theory of modules over group rings. Several applications of the theory under consideration are presented and problems concerning the residual nilpotence of one-relator groups are considered.

  2. Características estomáticas de pares congenéricos de cerrado e mata de galeria crescendo numa região transicional no Brasil central Stomatal traits of cerrado and gallery forest congeneric pairs growing in a transitional region in central Brazil

    Directory of Open Access Journals (Sweden)

    Davi Rodrigo Rossatto

    2009-06-01

    represent two distinct functional types. In this study we performed a comparative study of stomata anatomical characteristics, stomatal conductance and transpiration of 10 congeneric species pairs of cerrado and gallery forest species. Each pair was from a different family. Because stomatal anatomy and density affect the area and the path for gas diffusion through the stomatal pores, we also assessed possible relationships among the selected stomata traits and stomatal conductance. The area of the stomatal pore was the anatomical trait with the largest influence on gas exchange. Increases in pore area were correlated with an increase in stomatal conductance for most species. On the other hand, stomatal density was negatively correlated with both the length of the guard-cell and the area of the stomatal pore. The length of the stomatal pore and of the guard cell was significantly greater for cerrado species. However, most of the observed variation could be attributed to differences among genera, indicating that these stomatal traits are the product of the particular evolutionary history of each genus, and not the result of specialization to the cerrado or forest environment.

  3. Assessing stomatal conductance changes on short and long time scales and its possible impact on climate

    Science.gov (United States)

    Lammertsma, Emmy; Wagner-Cremer, Friederike; Kuerschner, Wolfram M.

    2010-05-01

    Two fundamental responses of vegetation to increasing atmospheric CO2 concentrations ([CO2]) are increased photosynthesis and decreased stomatal conductance. The latter is determined by both stomatal aperture adjustment on the short term, and by stomatal frequency and size adjustment on the long term. The resulting increased WUE of vegetation leads to changes in the hydrological cycle. Integrating this physiological forcing in Global Circulation Models (GCMs) results in increased surface warming and is thought to enhance terrestrial runoff significantly. Stomatal conductance is therefore considered a critical parameter in modelling past and future climate and environmental changes. However, quantification of the rate of change under [CO2] variability has proven to be not so straightforward. Values obtained from growth experiments under elevated [CO2] generally reflect the short term adaptation only, and seem to have too short a runtime for structural adaptation of the vegetation. Here we present the stomatal conductance changes deduced from Florida subfossil leaves over a 100ppmv [CO2] increment since the industrial revolution. Temporally high-resolution measurements of stomatal frequency and size on the epidermis for 8 common Florida tree species (Taxodium distichum, Pinus elliottii, P. taeda, Quercus nigra, Q. laurifolia, Acer rubrum, Myrica cerifera and Ilex cassine) are used to calculate the maximal stomatal conductance to water vapour Gwmax. Resulting conductance decreases over a 100ppmv [CO2] interval range between -19% to -59% for the different species, with an average of -40%. The current warm-temperate to subtropical Florida climate and vegetation composition serve as a modern analogue for Late Tertiary Europe, when [CO2] is thought to be comparable to today's levels. If it is assumed that past vegetation has responded similarly to [CO2] fluctuations, the stomatal conductance change reconstructed for Florida and related WUE changes can be used to better

  4. Diagnosis and management of recurrent herpetiform stomatitis and Behçet syndrome like recurrent aphthous stomatitis herpetiform type

    Directory of Open Access Journals (Sweden)

    Endah Ayu Tri Wulandari

    2008-11-01

    Full Text Available Recurrent Aphthous Stomatitis (RAS is a common inflammatory condition of the oral mucosa. The aetiology of RAS remains unclear, yet there are several predisposing factors which could be involved in the onset of the lesion. The herpetiform type of RAS appeared to be similar to recurrent oral Herpes Simplex infection and also could be part of Behçet Syndrome. This case report discussed a patient suffering from a herpetiform type of RAS with its clinical appearance resembling recurrent oral Herpes Simplex infection and Behçet syndrome. Initial treatment was undertaken based on the empirical treatment, yet the respond was not satisfactory. Then, laboratory tests were undertaken, including complete blood count, the total population of T lymphocyte, B lymphocyte, T helper, T suppressor, NK cells, T helper/T suppressor ratio, C3, C4, IgG, IgA, and IgM. These tests showed that there were immune and hematinic deficiency condition. Nevertheless, the clinical appearance, laboratory findings and consultation did not support the diagnosis of recurrent oral Herpes Simplex infection and Behçet Syndrome, thus, enhancing the definite diagnosis of the herpetiform type of RAS with immune and hematinic deficiency as the underlying condition. Based on the definite diagnosis, treatment plan was then revised to target the underlying condition.

  5. Measurement of transpiration in Pinus taeda L. and Liquidambar styraciflua L. in an environmental chamber using tritiated water

    Science.gov (United States)

    Levy, G. F.; Sonenshine, D. E.; Czoch, J. K.

    1976-01-01

    Transpiration rates of loblolly pine (Pinus taeda L.) and sweetgum (Liquidambar styraciflua L.) were measured at two different atmospheric water vapor pressure deficits (V.P.D.) in a controlled environment growth chamber using tritiated water as a tracer. The trees were maintained in a sealed plant bed containing a hydroponic nutrient solution into which labeled water (spike) was introduced. Samples of leaves, chamber air, spiked nutrient solution and control water were assayed for ratio-activity using liquid scintillation techniques to determine transpiration rates. The transpiration rate of sweetgum in ml./hr./gm. (4.95) was found to be 5 times greater than that of loblolly pine (1.03) at 1.84 V.P.D. and 8 times greater at 6.74 V.P.D. (15.99 for sweetgum vs. 2.19 for pine). Transpiration (based on measurements of leaf radioactivity) in both species rose with increasing deficit; however sweetgum increased its output by 3 times while pine only doubled its rate. Cyclical changes in transpiration rates were noted in both species; the sweetgum cycle required a 6 hour interval whereas the pine cycle required a 9 hour interval.

  6. Natural variation in stomatal response to closing stimuli among Arabidopsis thaliana accessions after exposure to lowe VPD as a tool to recognize the mechanism of disturbed stomatal functioning

    NARCIS (Netherlands)

    Ali Niaei Fard, S.; Meeteren, van U.

    2014-01-01

    Stomatal responses to closing stimuli are disturbed after long-term exposure of plants to low vapour pressure deficit (VPD). The mechanism behind this disturbance is not fully understood. Genetic variation between naturally occurring ecotypes can be helpful to elucidate the mechanism controlling

  7. Scaling of stomatal size and density optimizes allocation of leaf epidermal space for gas exchange in angiosperms

    Science.gov (United States)

    de Boer, Hugo Jan; Price, Charles A.; Wagner-Cremer, Friederike; Dekker, Stefan C.; Franks, Peter J.; Veneklaas, Erik J.

    2015-04-01

    Stomata on plant leaves are key traits in the regulation of terrestrial fluxes of water and carbon. The basic morphology of stomata consists of a diffusion pore and two guard cells that regulate the exchange of CO2 and water vapour between the leaf interior and the atmosphere. This morphology is common to nearly all land plants, yet stomatal size (defined as the area of the guard cell pair) and stomatal density (the number of stomata per unit area) range over three orders of magnitude across species. Evolution of stomatal sizes and densities is driven by selection pressure on the anatomical maximum stomatal conductance (gsmax), which determines the operational range of leaf gas exchange. Despite the importance of stomata traits for regulating leaf gas exchange, a quantitative understanding of the relation between adaptation of gsmax and the underlying co-evolution of stomatal sizes and densities is still lacking. Here we develop a theoretical framework for a scaling relationship between stomatal sizes and densities within the constraints set by the allocation of epidermal space and stomatal gas exchange. Our theory predicts an optimal scaling relationship that maximizes gsmax and minimizes epidermal space allocation to stomata. We test whether stomatal sizes and densities reflect this optimal scaling with a global compilation of stomatal trait data on 923 species reflecting most major clades. Our results show optimal scaling between stomatal sizes and densities across all species in the compiled data set. Our results also show optimal stomatal scaling across angiosperm species, but not across gymnosperm and fern species. We propose that the evolutionary flexibility of angiosperms to adjust stomatal sizes underlies their optimal allocation of leaf epidermal space to gas exchange.

  8. Hydrological effects of forest transpiration loss in bark beetle-impacted watersheds

    Science.gov (United States)

    Bearup, Lindsay A.; Maxwell, Reed M.; Clow, David W.; McCray, John E.

    2014-01-01

    The recent climate-exacerbated mountain pine beetle infestation in the Rocky Mountains of North America has resulted in tree death that is unprecedented in recorded history. The spatial and temporal heterogeneity inherent in insect infestation creates a complex and often unpredictable watershed response, influencing the primary storage and flow components of the hydrologic cycle. Despite the increased vulnerability of forested ecosystems under changing climate1, watershed-scale implications of interception, ground evaporation, and transpiration changes remain relatively unknown, with conflicting reports of streamflow perturbations across regions. Here, contributions to streamflow are analysed through time and space to investigate the potential for increased groundwater inputs resulting from hydrologic change after infestation. Results demonstrate that fractional late-summer groundwater contributions from impacted watersheds are 30 ± 15% greater after infestation and when compared with a neighbouring watershed that experienced earlier and less-severe attack, albeit uncertainty propagations through time and space are considerable. Water budget analysis confirms that transpiration loss resulting from beetle kill can account for the relative increase in groundwater contributions to streams, often considered the sustainable flow fraction and critical to mountain water supplies and ecosystems.

  9. A microfluidic pump/valve inspired by xylem embolism and transpiration in plants.

    Directory of Open Access Journals (Sweden)

    Li Jingmin

    Full Text Available In plants, transpiration draws the water upward from the roots to the leaves. However, this flow can be blocked by air bubbles in the xylem conduits, which is called xylem embolism. In this research, we present the design of a biomimetic microfluidic pump/valve based on water transpiration and xylem embolism. This micropump/valve is mainly composed of three parts: the first is a silicon sheet with an array of slit-like micropores to mimic the stomata in a plant leaf; the second is a piece of agarose gel to mimic the mesophyll cells in the sub-cavities of a stoma; the third is a micro-heater which is used to mimic the xylem embolism and its self-repairing. The solution in the microchannels of a microfluidic chip can be driven by the biomimetic "leaf" composed of the silicon sheet and the agarose gel. The halting and flowing of the solution is controlled by the micro-heater. Results have shown that a steady flow rate of 1.12 µl/min can be obtained by using this micropump/valve. The time interval between the turning on/off of the micro-heater and the halt (or flow of the fluid is only 2∼3 s. This micropump/valve can be used as a "plug and play" fluid-driven unit. It has the potential to be used in many application fields.

  10. Cooling Duct Analysis for Transpiration/Film Cooled Liquid Propellant Rocket Engines

    Science.gov (United States)

    Micklow, Gerald J.

    1996-01-01

    The development of a low cost space transportation system requires that the propulsion system be reusable, have long life, with good performance and use low cost propellants. Improved performance can be achieved by operating the engine at higher pressure and temperature levels than previous designs. Increasing the chamber pressure and temperature, however, will increase wall heating rates. This necessitates the need for active cooling methods such as film cooling or transpiration cooling. But active cooling can reduce the net thrust of the engine and add considerably to the design complexity. Recently, a metal drawing process has been patented where it is possible to fabricate plates with very small holes with high uniformity with a closely specified porosity. Such a metal plate could be used for an inexpensive transpiration/film cooled liner to meet the demands of advanced reusable rocket engines, if coolant mass flow rates could be controlled to satisfy wall cooling requirements and performance. The present study investigates the possibility of controlling the coolant mass flow rate through the porous material by simple non-active fluid dynamic means. The coolant will be supplied to the porous material by series of constant geometry slots machined on the exterior of the engine.

  11. An Experimental Investigation of Transpiration Cooling. Part I: Application of an Infrared Measurement Technique

    Directory of Open Access Journals (Sweden)

    J. H. Wang

    2003-01-01

    Full Text Available This study was an investigation into the application of the infrared thermal imaging technique (IRTIT to evaluate transpiration cooling performance through a porous wall. Two typical infrared thermograph systems, the AGA 782 short-wavelength system and the VARIOSCAN 3021 long-wavelength system, were employed to demonstrate the availability of the IRTIT measurement. In comparison with general infrared apparent temperature measurement, several factors that influence measurement accuracy need to be addressed in the application of the IRTIT in the region of transpiration cooling on the porous surfaces of turbine components. In this article, the influence of these factors on measurement accuracy is discussed, the corresponding calibration methods of the two infrared systems are described, and the ambient conditions and stability of the measurement are analyzed. Aporous circular tube was used as a specimen. The tube consisted of sintered chromium-nickel steel with a porosity of 21%. The experiment was carried out in the hotgas wind tunnel at the Institute of Thermal Turbomachinery at the University of Stuttgart, Stuttgart, Germany.

  12. Stomatal vs. genome size in angiosperms: the somatic tail wagging the genomic dog?

    Science.gov (United States)

    Hodgson, J G; Sharafi, M; Jalili, A; Díaz, S; Montserrat-Martí, G; Palmer, C; Cerabolini, B; Pierce, S; Hamzehee, B; Asri, Y; Jamzad, Z; Wilson, P; Raven, J A; Band, S R; Basconcelo, S; Bogard, A; Carter, G; Charles, M; Castro-Díez, P; Cornelissen, J H C; Funes, G; Jones, G; Khoshnevis, M; Pérez-Harguindeguy, N; Pérez-Rontomé, M C; Shirvany, F A; Vendramini, F; Yazdani, S; Abbas-Azimi, R; Boustani, S; Dehghan, M; Guerrero-Campo, J; Hynd, A; Kowsary, E; Kazemi-Saeed, F; Siavash, B; Villar-Salvador, P; Craigie, R; Naqinezhad, A; Romo-Díez, A; de Torres Espuny, L; Simmons, E

    2010-04-01

    Genome size is a function, and the product, of cell volume. As such it is contingent on ecological circumstance. The nature of 'this ecological circumstance' is, however, hotly debated. Here, we investigate for angiosperms whether stomatal size may be this 'missing link': the primary determinant of genome size. Stomata are crucial for photosynthesis and their size affects functional efficiency. Stomatal and leaf characteristics were measured for 1442 species from Argentina, Iran, Spain and the UK and, using PCA, some emergent ecological and taxonomic patterns identified. Subsequently, an assessment of the relationship between genome-size values obtained from the Plant DNA C-values database and measurements of stomatal size was carried out. Stomatal size is an ecologically important attribute. It varies with life-history (woody species < herbaceous species < vernal geophytes) and contributes to ecologically and physiologically important axes of leaf specialization. Moreover, it is positively correlated with genome size across a wide range of major taxa. Stomatal size predicts genome size within angiosperms. Correlation is not, however, proof of causality and here our interpretation is hampered by unexpected deficiencies in the scientific literature. Firstly, there are discrepancies between our own observations and established ideas about the ecological significance of stomatal size; very large stomata, theoretically facilitating photosynthesis in deep shade, were, in this study (and in other studies), primarily associated with vernal geophytes of unshaded habitats. Secondly, the lower size limit at which stomata can function efficiently, and the ecological circumstances under which these minute stomata might occur, have not been satisfactorally resolved. Thus, our hypothesis, that the optimization of stomatal size for functional efficiency is a major ecological determinant of genome size, remains unproven.

  13. Stomatal response of swordfern to volcanogenic CO2 and SO2 from Kilauea volcano

    Science.gov (United States)

    Tanner, Lawrence H.; Smith, David L.; Allan, Amanda

    2007-08-01

    The experimentally determined relationship between atmospheric pCO2 and plant stomata has been used to interpret large but transient changes in atmospheric composition, such as may have resulted from the eruptions of flood basalt. However, this relationship has not been tested in the field, i.e. in the vicinity of active volcanoes, to examine the specific effects of volcanogenic emissions. Moreover, the interpretation of paleoatmospheric pCO2 from fossil stomatal data assumes that the stomatal response resulted solely from variation in pCO2 and ignores the potential effect of outgassed SO2. We hypothesize that volcanogenic SO2 also has a significant effect on leaf stomata and test this hypothesis by measuring the stomatal index of the common swordfern (Nephrolepis exaltata) in the plumes of the actively outgassing vents of Kilauea volcano. We find that, compared to control locations, stomatal index is lowest at sample sites in the plume of Halema'uma'u Crater, where concentrations of both CO2 and SO2 are much higher than background. However, sites located directly in the plume of Pu'u O'o, where SO2 levels are high, but CO2 levels are not, also yield low values of stomatal index. We propose that shifts in the stomatal index of fossil leaves may record transient atmospheric increases in both SO2 and CO2, such as may be caused by eruptions of flood basalts. Calculations of pCO2 based on stomatal frequency are likely to be exaggerated.

  14. A Dynamic Hydro-Mechanical and Biochemical Model of Stomatal Conductance for C4Photosynthesis.

    Science.gov (United States)

    Bellasio, Chandra; Quirk, Joe; Buckley, Thomas N; Beerling, David J

    2017-09-01

    C 4 plants are major grain (maize [ Zea mays ] and sorghum [ Sorghum bicolor ]), sugar (sugarcane [ Saccharum officinarum ]), and biofuel ( Miscanthus spp.) producers and contribute ∼20% to global productivity. Plants lose water through stomatal pores in order to acquire CO 2 (assimilation [ A ]) and control their carbon-for-water balance by regulating stomatal conductance ( g S ). The ability to mechanistically predict g S and A in response to atmospheric CO 2 , water availability, and time is critical for simulating stomatal control of plant-atmospheric carbon and water exchange under current, past, or future environmental conditions. Yet, dynamic mechanistic models for g S are lacking, especially for C 4 photosynthesis. We developed and coupled a hydromechanical model of stomatal behavior with a biochemical model of C 4 photosynthesis, calibrated using gas-exchange measurements in maize, and extended the coupled model with time-explicit functions to predict dynamic responses. We demonstrated the wider applicability of the model with three additional C 4 grass species in which interspecific differences in stomatal behavior could be accounted for by fitting a single parameter. The model accurately predicted steady-state responses of g S to light, atmospheric CO 2 and oxygen, soil drying, and evaporative demand as well as dynamic responses to light intensity. Further analyses suggest that the effect of variable leaf hydraulic conductance is negligible. Based on the model, we derived a set of equations suitable for incorporation in land surface models. Our model illuminates the processes underpinning stomatal control in C 4 plants and suggests that the hydraulic benefits associated with fast stomatal responses of C 4 grasses may have supported the evolution of C 4 photosynthesis. © 2017 American Society of Plant Biologists. All Rights Reserved.

  15. Stomatal cell wall composition: distinctive structural patterns associated with different phylogenetic groups.

    Science.gov (United States)

    Shtein, Ilana; Shelef, Yaniv; Marom, Ziv; Zelinger, Einat; Schwartz, Amnon; Popper, Zoë A; Bar-On, Benny; Harpaz-Saad, Smadar

    2017-04-01

    Stomatal morphology and function have remained largely conserved throughout ∼400 million years of plant evolution. However, plant cell wall composition has evolved and changed. Here stomatal cell wall composition was investigated in different vascular plant groups in attempt to understand their possible effect on stomatal function. A renewed look at stomatal cell walls was attempted utilizing digitalized polar microscopy, confocal microscopy, histology and a numerical finite-elements simulation. The six species of vascular plants chosen for this study cover a broad structural, ecophysiological and evolutionary spectrum: ferns ( Asplenium nidus and Platycerium bifurcatum ) and angiosperms ( Arabidopsis thaliana and Commelina erecta ) with kidney-shaped stomata, and grasses (angiosperms, family Poaceae) with dumbbell-shaped stomata ( Sorghum bicolor and Triticum aestivum ). Three distinct patterns of cellulose crystallinity in stomatal cell walls were observed: Type I (kidney-shaped stomata, ferns), Type II (kidney-shaped stomata, angiosperms) and Type III (dumbbell-shaped stomata, grasses). The different stomatal cell wall attributes investigated (cellulose crystallinity, pectins, lignin, phenolics) exhibited taxon-specific patterns, with reciprocal substitution of structural elements in the end-walls of kidney-shaped stomata. According to a numerical bio-mechanical model, the end walls of kidney-shaped stomata develop the highest stresses during opening. The data presented demonstrate for the first time the existence of distinct spatial patterns of varying cellulose crystallinity in guard cell walls. It is also highly intriguing that in angiosperms crystalline cellulose appears to have replaced lignin that occurs in the stomatal end-walls of ferns serving a similar wall strengthening function. Such taxon-specific spatial patterns of cell wall components could imply different biomechanical functions, which in turn could be a consequence of differences in

  16. Clinical study on thermography, as modern investigation method for Candida-associated denture stomatitis.

    Science.gov (United States)

    Iosif, Laura; Preoteasa, Cristina Teodora; Murariu-Măgureanu, Cătălina; Preoteasa, Elena

    2016-01-01

    Candida-associated denture stomatitis is an infectious inflammatory condition of the oral mucosa, with frequent recurrences. The aim of this study was to assess the use of infrared thermography as investigation method for Candida-associated denture stomatitis (as inflammatory disorder of the maxillary denture bearing area), by comparing disease and non-disease groups. An observational study was conducted on maxillary edentulous patients treated by acrylic dentures, with and without Candida-associated denture stomatitis. Diagnostic test methods used were clinical examination for denture stomatitis and conventional microbiological culture method for oral candidiasis. Thermography analysis of the maxillary denture bearing area was made using the ThermaCAM PM350 infrared camera (Inframetrics, Flir Systems) and ThermaGram Pro 95 software, data being acquired by usage of standard protocol of thermographic registrations. The sample included 52 patients, 21 with and 31 without Candida-associated denture stomatitis. The temperature of the maxillary mucosa corresponding to the denture bearing area was found to be statistically significantly higher in Candida-associated denture stomatitis (mean 36.20°C), compared to healthy oral mucosa (mean 34.85°C). The thermal threshold value of 35.44°C was identified as best differentiating a pathological from normal state of the maxillary mucosa corresponding to the denture bearing area. In conclusion, infrared thermography, a rapid non-invasive investigation method, has the premises to bring valuable data in inflammatory disorders of the maxillary denture bearing area, as Candida-associated denture stomatitis that may be used for screening, diagnostic or monitoring purposes.

  17. Stomatal characterization of five species of the genus Vanilla

    International Nuclear Information System (INIS)

    Reyes-Lopez, Delfino; Quiroz-Valentin, Jonathan; Kelso-Bucio, Henry Arturo; Huerta-Lara, Manuel; Avendano-Arrazate, Carlos Hugo; Lobato-Ortiz, Ricardo

    2015-01-01

    The stomata of five species of vanilla were characterized. Throughout 2012, leaf samples of V. planifolia G. Jackson, V. pompona Schiede, V. inodora Schiede, V. insignis Ames and V. odorota Presl were taken from the vanilla germplasm bank at the Benemerita Universidad Autonoma de Puebla, throughout 2012. The stomata size was obtained considering their length and width, as well as the index and stomata number of the abaxial and adaxial leaf surfaces in a randomized complete block design with three replications. The highest stomatal index with 8713 and 8246 stomata per mm 2 , was showed in V. pompona Schiede an V. inodora Schiede respectively, followed by V. odorata Presl with 4412 stomata per mm 2 . The lowest stomata index with 2968 and 1378 stomata per mm 2 , was showed by V. insignis Ames and V. planifolia G. Jackson respectively, in the abaxial leaf surface, these differences were statistically significant (p≤0,05). According to the position of the leaf stomata, V. planifolia G. Jackson and V. inodora Schiede can be considered to be hypostomatics since they showed stomata only in the abaxial leaf surface. V. insignis Ames, V. inodora Schiede and V. odorata Presl. can be considered to be anfiestomatic because they showed stomata in both the abaxial and adaxial leaf surfaces. V. inodora Schiede has had smaller stomata compared with the other species. That is an important feature to be included in the genetic improvement of the genus Vanilla, because due to climate change, temperature will increase and precipitation will decrease, so Vainilla will require more efficient genotypes for water use. (author) [es

  18. Sociodemographic and clinical characteristics of patients with recurrent aphthous stomatitis

    Directory of Open Access Journals (Sweden)

    Anıl Gülsel Bahalı

    2014-12-01

    Full Text Available Background and Design: The purpose of this study was to obtain data that may provide an insight into the etiopathogenesis of recurrent aphtous stomatitis (RAS by the way of analysing the sociodemographic and clinical characteristics of patients who had been diagnosed with RAS. Materials and Metods: The patients, who were diagnosed with RAS in the dermatology outpatient clinic, between May 2007 and May 2010, were evaluated retrospectively. The data including sociodemografic and clinical characteristics, and treatment options were recorded. Results: A hundred patients (68 women, 32 men were included in this study. The average age was 40±13.6 years. RAS was more common in patients with middle-income and low education. The most common type of RAS was minor aphtous ulcers (88%. The lesions were most frequently seen on the lateral side of the tongue (34% and cheek (34%. Sixty percent of patients had a positive family history. Some factors such as biting (12%, tooth brushing (18%, dental disease presence (82%, food (39%, menstruation (10.3%, stress (76%, iron deficiency (16.7%, vitamin B12 deficiency (22.4%, low serum ferritin levels (18%, and seasonal variability (32% showed positive correlation with RAS. A negative correlation was found between RAS and smoking. Forty-nine percent of patients had used alternative therapies in addition to drug therapy. The most frequently used alternative method was consumption of sumac (26.5%. Conlucions: In contrast to the literature, our study found that RAS is started in the third decade of life and, approximately 50% of patients prefered alternative treatment methods, particularly sumac. Nowadays, discussions about the etiopathogenesis of RAS continue. In this study, we found that different sociodemographic and clinical factors may be associated with the etiopathogenesis of the disease. Our study will be followed by further studies using prospective design to identify the the etiopathogenesis of RAS.

  19. Stomatal characterization of five species of the genus Vanilla.

    Directory of Open Access Journals (Sweden)

    Delfino Reyes-López

    2015-06-01

    Full Text Available The objective was to characterize the stomata of five species of vanilla. Throughout 2012, leaf samples of V. planifolia G. Jackson, V. pompona Schiede, V. indora Schiede, V. insignis Ames and V. odorota Presl were taken from the vanilla germplasm bank at the Benemérita Universidad Autónoma de Puebla. The stomata size was obtained considering their length and width, as well as the index and stomata number of the abaxial and adaxial leaf surfaces in a randomized complete block design with three replications. V. pompona Schiede and V. inodora Schiede showed the highest stomatal index with 8713 and 8246 stomata per mm2, respectively, followed by V. odorata Presl with 4412 stomata per mm2. V. insignis Ames and V. planifolia G. Jackson showed the lowest stomata index with 2968 and 1378 stomata per mm2, respectively, in the abaxial leaf surface, these differences were statistically significant (P≤0.05. According to the position of the leaf stomata, V. planifolia G. Jackson and V. inodora Schiede can be considered to be hypostomatics since they showed stomata only in the abaxial leaf surface. V. insignis Ames, V. inodora Schiede and V. odorata Presl. can be considered to be anfiestomatic because they showed stomata in both the abaxial and adaxial leaf surfaces. V. inodora Schiede had smaller stomata compared with the other species.That is an important feature to be included in the genetic improvement of the genus Vanilla, because due to climate change, temperature will increase and precipitation will decrease, so Vainilla will require more efficient genotypes for water use.

  1. Contrasting responses of leaf stomatal characteristics to climate change: a considerable challenge to predict carbon and water cycles.

    Science.gov (United States)

    Yan, Weiming; Zhong, Yangquanwei; Shangguan, Zhouping

    2017-09-01

    Stomata control the cycling of water and carbon between plants and the atmosphere; however, no consistent conclusions have been drawn regarding the response of stomatal frequency to climate change. Here, we conducted a meta-analysis of 1854 globally obtained data series to determine the response of stomatal frequency to climate change, which including four plant life forms (over 900 species), at altitudes ranging from 0 to 4500 m and over a time span of more than one hundred thousand years. Stomatal frequency decreased with increasing CO 2 concentration and increased with elevated temperature and drought stress; it was also dependent on the species and experimental conditions. The response of stomatal frequency to climate change showed a trade-off between stomatal control strategies and environmental factors, such as the CO 2 concentration, temperature, and soil water availability. Moreover, threshold effects of elevated CO 2 and temperature on stomatal frequency were detected, indicating that the response of stomatal density to increasing CO 2 concentration will decrease over the next few years. The results also suggested that the stomatal index may be more reliable than stomatal density for determination of the historic CO 2 concentration. Our findings indicate that the contrasting responses of stomata to climate change bring a considerable challenge in predicting future water and carbon cycles. © 2017 John Wiley & Sons Ltd.

  2. Functional Analysis of Cellulose and Xyloglucan in the Walls of Stomatal Guard Cells of Arabidopsis1[OPEN

    Science.gov (United States)

    Rui, Yue; Anderson, Charles T.

    2016-01-01

    Stomatal guard cells are pairs of specialized epidermal cells that control water and CO2 exchange between the plant and the environment. To fulfill the functions of stomatal opening and closure that are driven by changes in turgor pressure, guard cell walls must be both strong and flexible, but how the structure and dynamics of guard cell walls enable stomatal function remains poorly understood. To address this question, we applied cell biological and genetic analyses to investigate guard cell walls and their relationship to stomatal function in Arabidopsis (Arabidopsis thaliana). Using live-cell spinning disk confocal microscopy, we measured the motility of cellulose synthase (CESA)-containing complexes labeled by green fluorescent protein (GFP)-CESA3 and observed a reduced proportion of GFP-CESA3 particles colocalizing with microtubules upon stomatal closure. Imaging cellulose organization in guard cells revealed a relatively uniform distribution of cellulose in the open state and a more fibrillar pattern in the closed state, indicating that cellulose microfibrils undergo dynamic reorganization during stomatal movements. In cesa3je5 mutants defective in cellulose synthesis and xxt1 xxt2 mutants lacking the hemicellulose xyloglucan, stomatal apertures, changes in guard cell length, and cellulose reorganization were aberrant during fusicoccin-induced stomatal opening or abscisic acid-induced stomatal closure, indicating that sufficient cellulose and xyloglucan are required for normal guard cell dynamics. Together, these results provide new insights into how guard cell walls allow stomata to function as responsive mediators of gas exchange at the plant surface. PMID:26729799

  3. Sound Propagation in Saturated Gas-Vapor-Droplet Suspensions Considering the Effect of Transpiration on Droplet Evaporation

    Science.gov (United States)

    Kandula, Max

    2012-01-01

    The Sound attenuation and dispersion in saturated gas-vapor-droplet mixtures with evaporation has been investigated theoretically. The theory is based on an extension of the work of Davidson (1975) to accommodate the effects of transpiration on the linear particle relaxation processes of mass, momentum and energy transfer. It is shown that the inclusion of transpiration in the presence of mass transfer improves the agreement between the theory and the experimental data of Cole and Dobbins (1971) for sound attenuation in air-water fogs at low droplet mass concentrations. The results suggest that transpiration has an appreciable effect on both sound absorption and dispersion for both low and high droplet mass concentrations.

  4. The effects of elevated CO2 and nitrogen fertilization on stomatal conductance estimated from 11 years of scaled sap flux measurements at Duke FACE.

    Science.gov (United States)

    Ward, Eric J; Oren, Ram; Bell, David M; Clark, James S; McCarthy, Heather R; Kim, Hyun-Seok; Domec, Jean-Christophe

    2013-02-01

    In this study, we employ a network of thermal dissipation probes (TDPs) monitoring sap flux density to estimate leaf-specific transpiration (E(L)) and stomatal conductance (G(S)) in Pinus taeda (L.) and Liquidambar styraciflua L. exposed to +200 ppm atmospheric CO(2) levels (eCO(2)) and nitrogen fertilization. Scaling half-hourly measurements from hundreds of sensors over 11 years, we found that P. taeda in eCO(2) intermittently (49% of monthly values) decreased stomatal conductance (G(S)) relative to the control, with a mean reduction of 13% in both total E(L) and mean daytime G(S). This intermittent response was related to changes in a hydraulic allometry index (A(H)), defined as sapwood area per unit leaf area per unit canopy height, which decreased a mean of 15% with eCO(2) over the course of the study, due mostly to a mean 19% increase in leaf area (A(L)). In contrast, L. styraciflua showed a consistent (76% of monthly values) reduction in G(S) with eCO(2) with a total reduction of 32% E(L), 31% G(S) and 23% A(H) (due to increased A(L) per sapwood area). For L. styraciflua, like P. taeda, the relationship between A(H) and G(S) at reference conditions suggested a decrease in G(S) across the range of A(H). Our findings suggest an indirect structural effect of eCO(2) on G(S) in P. taeda and a direct leaf level effect in L. styraciflua. In the initial year of fertilization, P. taeda in both CO(2) treatments, as well as L. styraciflua in eCO(2), exhibited higher G(S) with N(F) than expected from shifts in A(H), suggesting a transient direct effect on G(S). Whether treatment effects on mean leaf-specific G(S) are direct or indirect, this paper highlights that long-term treatment effects on G(S) are generally reflected in A(H) as well.

  5. Carbonic anhydrases are upstream regulators of CO2-controlled stomatal movements in guard cells

    KAUST Repository

    Hu, Honghong

    2009-12-13

    The continuing rise in atmospheric CO2 causes stomatal pores in leaves to close and thus globally affects CO2 influx into plants, water use efficiency and leaf heat stress. However, the CO2-binding proteins that control this response remain unknown. Moreover, which cell type responds to CO2, mesophyll or guard cells, and whether photosynthesis mediates this response are matters of debate. We demonstrate that Arabidopsis thaliana double-mutant plants in the beta-carbonic anhydrases betaCA1 and betaCA4 show impaired CO2-regulation of stomatal movements and increased stomatal density, but retain functional abscisic-acid and blue-light responses. betaCA-mediated CO2-triggered stomatal movements are not, in first-order, linked to whole leaf photosynthesis and can function in guard cells. Furthermore, guard cell betaca-overexpressing plants exhibit instantaneous enhanced water use efficiency. Guard cell expression of mammalian alphaCAII complements the reduced sensitivity of ca1 ca4 plants, showing that carbonic anhydrase-mediated catalysis is an important mechanism for betaCA-mediated CO2-induced stomatal closure and patch clamp analyses indicate that CO2/HCO3- transfers the signal to anion channel regulation. These findings, together with ht1-2 (ref. 9) epistasis analysis demonstrate that carbonic anhydrases function early in the CO2 signalling pathway, which controls gas-exchange between plants and the atmosphere.

  6. Actin Filaments in Mature Guard Cells Are Radially Distributed and Involved in Stomatal Movement.

    Science.gov (United States)

    Kim, M.; Hepler, P. K.; Eun, S. O.; Ha, K. S.; Lee, Y.

    1995-11-01

    Stomatal movements, which regulate gas exchange in plants, involve pronounced changes in the shape and volume of the guard cell. To test whether the changes are regulated by actin filaments, we visualized microfilaments in mature guard cells and examined the effects of actin antagonists on stomatal movements. Immunolocalization on fixed cells and microinjection of fluorescein isothiocyanate-phalloidin into living guard cells of Commelina communis L. showed that cortical microfilaments were radially distributed, fanning out from the stomatal pore site, resembling the known pattern of microtubules. Treatment of epidermal peels with phalloidin prior to stabilizing microfilaments with m-maleimidobenzoyl N-hydroxysuccimimide caused dense packing of radial microfilaments and an accumulation of actin around many organelles. Both stomatal closing induced by abscisic acid and opening under light were inhibited. Treatment of guard cells with cytochalasin D abolished the radial pattern of microfilaments; generated sparse, poorly oriented arrays; and caused partial opening of dark-closed stomata. These results suggest that microfilaments participate in stomatal aperture regulation.

  7. Ozone slows stomatal response to light and leaf wounding in a Mediterranean evergreen broadleaf, Arbutus unedo

    International Nuclear Information System (INIS)

    Paoletti, Elena

    2005-01-01

    The effect of a 90-d ozone exposure (charcoal-filtered air or 110 nmol mol -1 O 3 ) on stomatal conductance (g s ) was investigated in the Mediterranean evergreen broadleaf Arbutus unedo L. Ozone did not significantly reduce midday steady-state g s compared to controls. However, it slowed stomatal response to abrupt reduction of light intensity and to increasing water stress, applied by severing the leaf midrib. Ozone slowed stomatal closure, rather than aperture. Nevertheless, vein-cutting did not allow ozonated leaves to reach the pre-injury g s levels, like controls did, suggesting re-opening was still, slowly in progress. The sluggish behaviour was recorded 10 days after cessation of O 3 exposure ('memory effect') and may affect stomatal control in response to sunflecks and leaf wounding. Mediterranean evergreen broadleaves are regarded as tolerant to O 3 exposure. Nevertheless, measurements of steady-state g s at midday may not account for altered stomatal responses to stressors. - In response to ozone exposure, stomata were slower in closing rather than in opening

  8. Ethylene limits abscisic acid- or soil drying-induced stomatal closure in aged wheat leaves.

    Science.gov (United States)

    Chen, Lin; Dodd, Ian C; Davies, William J; Wilkinson, Sally

    2013-10-01

    The mechanism of age-induced decreased stomatal sensitivity to abscisic acid (ABA) and soil drying has been explored here. Older, fully expanded leaves partly lost their ability to close stomata in response to foliar ABA sprays, and soil drying which stimulated endogenous ABA production, while young fully expanded leaves closed their stomata more fully. However, ABA- or soil drying-induced stomatal closure of older leaves was partly restored by pretreating plants with 1-methylcyclopropene (1-MCP), which can antagonize ethylene receptors, or by inoculating soil around the roots with the rhizobacterium Variovorax paradoxus 5C-2, which contains 1-aminocyclopropane-1-carboxylic acid (ACC)-deaminase. ACC (the immediate biosynthetic precursor of ethylene) sprays revealed higher sensitivity of stomata to ethylene in older leaves than younger leaves, despite no differences in endogenous ACC concentrations or ethylene emission. Taken together, these results indicate that the relative insensitivity of stomatal closure to ABA and soil drying in older leaves is likely due to altered stomatal sensitivity to ethylene, rather than ethylene production. To our knowledge, this is the first study to mechanistically explain diminished stomatal responses to soil moisture deficit in older leaves, and the associated reduction in leaf water-use efficiency. © 2013 John Wiley & Sons Ltd.

  9. Ultrastructure of stomatal development in early-divergent angiosperms reveals contrasting patterning and pre-patterning.

    Science.gov (United States)

    Rudall, Paula J; Knowles, Emma V W

    2013-10-01

    Angiosperm stomata consistently possess a pair of guard cells, but differ between taxa in the patterning and developmental origin of neighbour cells. Developmental studies of phylogenetically pivotal taxa are essential as comparative yardsticks for understanding the evolution of stomatal development. We present a novel ultrastructural study of developing stomata in leaves of Amborella (Amborellales), Nymphaea and Cabomba (Nymphaeales), and Austrobaileya and Schisandra (Austrobaileyales), representing the three earliest-divergent lineages of extant angiosperms (the ANITA-grade). Alternative developmental pathways occur in early-divergent angiosperms, resulting partly from differences in pre-patterning and partly from the presence or absence of highly polarized (asymmetric) mitoses in the stomatal cell lineage. Amplifying divisions are absent from ANITA-grade taxa, indicating that ostensible similarities with the stomatal patterning of Arabidopsis are superficial. In Amborella, 'squared' pre-patterning occurs in intercostal regions, with groups of four protodermal cells typically arranged in a rectangle; most guard-mother cells are formed by asymmetric division of a precursor cell (the mesoperigenous condition) and are typically triangular or trapezoidal. In contrast, water-lily stomata are always perigenous (lacking asymmetric divisions). Austrobaileya has occasional 'giant' stomata. Similar mature stomatal phenotypes can result from contrasting morphogenetic factors, although the results suggest that paracytic stomata are invariably the product of at least one asymmetric division. Loss of asymmetric divisions in stomatal development could be a significant factor in land plant evolution, with implications for the diversity of key structural and physiological pathways.

  10. Bioenergy Sorghum Crop Model Predicts VPD-Limited Transpiration Traits Enhance Biomass Yield in Water-Limited Environments.

    Science.gov (United States)

    Truong, Sandra K; McCormick, Ryan F; Mullet, John E

    2017-01-01

    Bioenergy sorghum is targeted for production in water-limited annual cropland therefore traits that improve plant water capture, water use efficiency, and resilience to water deficit are necessary to maximize productivity. A crop modeling framework, APSIM, was adapted to predict the growth and biomass yield of energy sorghum and to identify potentially useful traits for crop improvement. APSIM simulations of energy sorghum development and biomass accumulation replicated results from field experiments across multiple years, patterns of rainfall, and irrigation schemes. Modeling showed that energy sorghum's long duration of vegetative growth increased water capture and biomass yield by ~30% compared to short season crops in a water-limited production region. Additionally, APSIM was extended to enable modeling of VPD-limited transpiration traits that reduce crop water use under high vapor pressure deficits (VPDs). The response of transpiration rate to increasing VPD was modeled as a linear response until a VPD threshold was reached, at which the slope of the response decreases, representing a range of responses to VPD observed in sorghum germplasm. Simulation results indicated that the VPD-limited transpiration trait is most beneficial in hot and dry regions of production where crops are exposed to extended periods without rainfall during the season or to a terminal drought. In these environments, slower but more efficient transpiration increases biomass yield and prevents or delays the exhaustion of soil water and onset of leaf senescence. The VPD-limited transpiration responses observed in sorghum germplasm increased biomass accumulation by 20% in years with lower summer rainfall, and the ability to drastically reduce transpiration under high VPD conditions could increase biomass by 6% on average across all years. This work indicates that the productivity and resilience of bioenergy sorghum grown in water-limited environments could be further enhanced by development

  11. The Amazon forest-rainfall feedback: the roles of transpiration and interception

    Science.gov (United States)

    Dekker, Stefan; Staal, Arie; Tuinenburg, Obbe

    2017-04-01

    In the Amazon, deep-rooted trees increase local transpiration and high tree cover increase local interception evaporation. These increased local evapotranspiration fluxes to the atmosphere have both positive effects on forests down-wind, as they stimulate rainfall. Although important for the functioning of the Amazon, we have an inadequate assessment on the strength and the timing of these forest-rainfall feedbacks. In this study we (i) estimate local forest transpiration and local interception evaporation, (ii) simulate the trajectories of these moisture flows through the atmosphere and (iii) quantify their contributions to the forest-rainfall feedback for the whole Amazon basin. To determine the atmospheric moisture flows in tropical South America we use a Lagrangian moisture tracking algorithm on 0.25° (c. 25 km) resolution with eight atmospheric layers on a monthly basis for the period 2003-2015. With our approach we account for multiple re-evaporation cycles of this moisture. We also calculate for each month the potential effects of forest loss on evapotranspiration. Combined, these calculations allow us to simulate the effects of land-cover changes on rainfall in downwind areas and estimate the effect on the forest. We found large regional and temporal differences in the importance how forest contribute to rainfall. The transpiration-rainfall feedback is highly important during the dry season. Between September-November, when large parts of the Amazon are at the end of the dry season, more than 50% of the rainfall is caused by the forests upstream. This means that droughts in the Amazon are alleviated by the forest. Furthermore, we found that much moisture cycles several times during its trajectory over the Amazon. After one evapotranspiration-rainfall cycle, more than 40% of the moisture is re-evaporated again. The interception-evaporation feedback is less important during droughts. Finally from our analysis, we show that the forest-rainfall feedback is

  12. The Guard Cell Metabolome: Functions in Stomatal Movement and Global Food Security

    Directory of Open Access Journals (Sweden)

    Biswapriya eMisra

    2015-05-01

    Full Text Available Guard cells represent a unique single cell-type system for the study of cellular responses to abiotic and biotic perturbations that affect stomatal movement. Decades of effort through both classical physiological and functional genomics approaches have generated an enormous amount of information on the roles of individual metabolites in stomatal guard cell function and physiology. Recent application of metabolomics methods has produced a substantial amount of new information on metabolome control of stomatal movement. In conjunction with other ‘omics’ approaches, the knowledge-base is growing to reach a systems-level description of this single cell-type. Here we summarize current knowledge of the guard cell metabolome and highlight critical metabolites that bear significant impact on future engineering and breeding efforts to generate plants/crops that are resistant to environmental challenges and produce high yield and quality products for food and energy security.

  13. Ulcerative Uremic Stomatitis - Review of the Literature and A Rare Case Report

    Directory of Open Access Journals (Sweden)

    Shantala Arunkumar

    2015-01-01

    Full Text Available Uremic Stomatitis (US represents a comparatively uncommon intraoral complication seen, mostly, in cases of end-stage renal disease or undiagnosed or untreated chronic renal failure. Its frequency has diminished due to the advent of renal dialysis. Clinically uremic stomatitis is characterized by the presence of painful plaques and crusts that are usually distributed on the buccal and labial mucosa, dorsal or ventral surface of the tongue, gingiva, and floor of the mouth. Ultimate treatment consists of improvement of blood urea concentration and underlying renal failure is supported by enhancement of oral hygiene with antiseptic mouthwashes and antimicrobial/antifungal agents, if necessary. Here we report a rare case of ulcerative type of uremic stomatitis occurring in a patient of chronic renal failure due to sudden relapse of uremia and reviewed the possible pathophysiology of oral symptoms of chronic renal failure.

  14. Stimulation of Vesicular Stomatitis Virus in vitro RNA Synthesis by Microtubule-Associated Proteins

    Science.gov (United States)

    Hill, Virginia M.; Harmon, Shirley A.; Summers, Donald F.

    1986-08-01

    Microtubule-associated proteins purified from bovine brains stimulated the in vitro transcription and replication reactions of vesicular stomatitis virus. The products of these reactions were intact messenger or genome-sized RNA species. A preparation from HeLa cells containing tubulin and microtubule-associated proteins also stimulated vesicular stomatitis virus transcription in vitro. This observation is in accord with previous studies, which suggested that a host cell factor was involved with the function of the vesicular stomatitis virus RNA polymerase, and others that indicated that several animal viruses displayed an association with host cell cytoskeletal elements during their replication cycles. We show evidence in this report of a host cell protein that seems to have a functional role in interacting with the virion polymerase.

  15. Effect of night temperature on daytime stomatal conductance in early and late successional plants.

    Science.gov (United States)

    Drew, A P; Bazzaz, F A

    1982-01-01

    Sixteen annuals, biennials, and herbaceous and woody perennials characteristic of early and late successional old field ecosystems and upland and floodplain habitats were analyzed for their response of stomatal conductance to changes in night temperature. Early successional species that germinate in early spring when temperatures are low, but above freezing are insensitive to cool nights, i.e., their conductance in the following days is unaffected by low night temperature. Later spring and summer-emerging species' stomatal conductance is inhibited by low temperatures. Tree species show the same effects and in some an enhancement of stomatal conductance by low night temperatures was observed. However, adaptive differences in response to night temperatures appear related to both phenology of germination and growth and habitat types.

  16. Oral symptoms and salivary findings in oral lichen planus, oral lichenoid lesions and stomatitis

    DEFF Research Database (Denmark)

    Larsen, Kristine Roen; Johansen, Jeanne Duus; Reibel, Jesper

    2017-01-01

    BACKGROUND: To examine if patients with oral lichen planus, oral lichenoid lesions and generalised stomatitis and concomitant contact allergy have more frequent and severe xerostomia, lower unstimulated and chewing-stimulated saliva and citric-acid-stimulated parotid saliva flow rates, and higher...... of xerostomia, clinical examination, sialometry, mucosal biopsy and contact allergy testing. RESULTS: Nineteen patients had oral lichen planus, 19 patients had oral lichenoid lesions and 11 patients had generalised stomatitis. 38.8% had contact allergy. Xerostomia was significantly more common and severe...... in the chewing stimulated saliva samples from patients when compared to healthy controls. The differences were not significant and they were irrespective of the presence of contact allergy. CONCLUSION: Xerostomia is prevalent in patients with oral lichen planus, lichenoid lesions and generalised stomatitis...

  17. Effect of Vertical Canopy Architecture on Transpiration, Thermoregulation and Carbon Assimilation

    Directory of Open Access Journals (Sweden)

    Tirtha Banerjee

    2018-04-01

    Full Text Available Quantifying the impact of natural and anthropogenic disturbances such as deforestation, forest fires and vegetation thinning among others on net ecosystem—atmosphere exchanges of carbon dioxide, water vapor and heat—is an important aspect in the context of modeling global carbon, water and energy cycles. The absence of canopy architectural variation in horizontal and vertical directions is a major source of uncertainty in current climate models attempting to address these issues. This manuscript demonstrates the importance of considering the vertical distribution of foliage density by coupling a leaf level plant biophysics model with analytical solutions of wind flow and light attenuation in a horizontally homogeneous canopy. It is demonstrated that plant physiological response in terms of carbon assimilation, transpiration and canopy surface temperature can be widely different for two canopies with the same leaf area index (LAI but different leaf area density distributions, under several conditions of wind speed, light availability, soil moisture availability and atmospheric evaporative demand.

  18. Development and assessment of Transpirative Deficit Index (D-TDI) for agricultural drought monitoring

    Science.gov (United States)

    Borghi, Anna; Rienzner, Michele; Gandolfi, Claudio; Facchi, Arianna

    2017-04-01

    Drought is a major cause of crop yield loss, both in rainfed and irrigated agroecosystems. In past decades, many approaches have been developed to assess agricultural drought, usually based on the monitoring or modelling of the soil water content condition. All these indices show weaknesses when applied for a real time drought monitoring and management at the local scale, since they do not consider explicitly crops and soil properties at an adequate spatial resolution. This work describes a newly developed agricultural drought index, called Transpirative Deficit Index (D-TDI), and assesses the results of its application over a study area of about 210 km2 within the Po River Plain (northern Italy). The index is based on transforming the interannual distribution of the transpirative deficit (potential crop transpiration minus actual transpiration), calculated daily by means of a spatially distributed conceptual hydrological model and cumulated over user-selected time-steps, to a standard normal distribution (following the approach proposed by the meteorological index SPI - Standard Precipitation Index). For the application to the study area a uniform maize crop cover (maize is the most widespread crop in the area) and 22-year (1993-2014) meteorological data series were considered. Simulation results consist in maps of the index cumulated over 10-day time steps over a mesh with cells of 250 m. A correlation analysis was carried out (1) to study the characteristics and the memory of D-TDI and to assess its intra- and inter-annual variability, (2) to assess the response of the agricultural drought (i.e., the information provided by D-TDI) to the meteorological drought computed through the SPI over different temporal steps. The D-TDI is positively auto-correlated with a persistence of 30 days, and positively cross-correlated to the SPI with a persistence of 40 days, demonstrating that D-TDI responds to meteorological forcing. Correlation analyses demonstrate that soils

  19. Absence of Hg transpiration by shoot after Hg uptake by roots of six terrestrial plant species

    International Nuclear Information System (INIS)

    Greger, Maria; Wang Yaodong; Neuschuetz, Clara

    2005-01-01

    In this paper we investigated if, and to what extent, six different plant species accumulate, translocate and emit mercury (Hg) into the air. The Hg uptake by roots, distribution of Hg to the shoot and release of Hg via shoots of garden pea, spring wheat, sugar beet, oil-seed rape, white clover and willow were investigated in a transpiration chamber. The airborne Hg was trapped in a Hopcalite trap or a gold trap. Traps and plant materials were analysed for content of Hg by CVAAS. The results show that all plant species were able to take up Hg to a large extent from a nutrient solution containing 200 μg L -1 Hg. However, the Hg translocation to the shoot was low (0.17-2.5%) and the Hg that reached the leaves was trapped and no release of the absorbed Hg to the air was detected. - Mercury translocation to shoots was low

  20. Observations of leaf stomatal conductance at the canopy scale: an atmospheric modeling perspective

    International Nuclear Information System (INIS)

    Avissar, R.

    1993-01-01

    Plant stomata play a key role in the redistribution of energy received on vegetated land into sensible and latent heat. As a result, they have a considerable impact on the atmospheric planetary boundary layer, the hydrologic cycle, the climate, and the weather. Current parameterizations of the stomatal mechanism in state-of-the-art atmospheric models are based on empirical relations that are established at the leaf scale between stomatal conductance and environmental conditions. In order to evaluate these parameterizations, an experiment was carried out on a potato field in New Jersey during the summer of 1989. Stomatal conductances were measured within a small homogeneous area in the middle of the potato field and under a relatively broad range of atmospheric conditions. A large variability of stomatal conductances was observed. This variability, which was associated with the variability of micro-environmental and physiological conditions that is found even in a homogeneous canopy, cannot be simulated explicitly on the scale of a single agricultural field and,a fortiori, on the scale of atmospheric models. Furthermore, this variability could not be related to the environmental conditions measured at a height of 2 m above the plant canopy simultaneously with the conductances, reinforcing the concept of scale decoupling suggested by Jarvis and McNaughton (1986) and McNaughton and Jarvis (1991). Thus, for atmospheric modeling purposes, a parameterization of stomatal conductance at the canopy scale using external environmental forcing conditions seems more appropriate than a parameterization based on leaf-scale stomatal conductance, as currently adopted in state-of-the-art atmospheric models. The measured variability was characterized by a lognormal probability density function (pdf) that remained relatively stable during the entire measuring period. These observations support conclusions by McNaughton and Jarvis (1991) that, unlike current parameterizations, a

  1. Observations of leaf stomatal conductance at the canopy scale: an atmospheric modeling perspective

    International Nuclear Information System (INIS)

    Avissar, R.

    1993-01-01

    Plant stomata play a key role in the redistribution of energy received on vegetated land into sensible and latent heat. As a result, they have a considerable impact on the atmospheric planetary boundary layer, the hydrologic cycle, the climate, and the weather. Current parameterizations of the stomatal mechanism in state-of-the-art atmospheric models are based on empirical relations that are established at the leaf scale between stomatal conductance and environmental conditions. In order to evaluate these parameterizations, an experiment was carried out on a potato field in New Jersey during the summer of 1989. Stomatal conductances were measured within a small homogeneous area in the middle of the potato field and under a relatively broad range of atmospheric conditions. A large variability of stomatal conductances was observed. This variability, which was associated with the variability of micro-environmental and physiological conditions that is found even in a homogeneous canopy, cannot be simulated explicitly on the scale of a single agricultural field and, a fortiori, on the scale of atmospheric models. Furthermore, this variability could not be related to the environmental conditions measured at a height of 2 m above the plant canopy simultaneously with the conductances, reinforcing the concept of scale decoupling suggested by Jarvis and McNaughton (1986) and McNaughton and Jarvis (1991). Thus, for atmospheric modeling purposes, a parameterization of stomatal conductance at the canopy scale using external environmental forcing conditions seems more appropriate than a parameterization based on leaf-scale stomatal conductance, as currently adopted in state-of-the-art atmospheric models. The measured variability was characterized by a lognormal probability density function (pdf) that remained relatively stable during the entire measuring period. These observations support conclusions by McNaughton and Jarvis (1991) that, unlike current parameterizations, a

  2. Canopy Stomatal Conductance Unlocks Partitioning of Ecosystem-Atmosphere Carbon and Water Exchanges

    Science.gov (United States)

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

    2016-12-01

    Stomata are a key nexus in biosphere-atmosphere interactions: the gateway for both carbon gain and water loss by plant canopies. Accurate quantification of canopy stomatal conductance enables partitioning of both evapotranspiration (ET) and net ecosystem-atmosphere CO2 exchange (NEE)—the latter via CO2 isotope flux measurements. To those ends, we determined the behavior of canopy stomatal conductance in a temperate deciduous forest based on heat and water vapor flux measurements, and validated that determination based on uptake of carbonyl sulfide, which also passes through the stomata. We found that the canopy stomatal conductance followed a simple empirical function of leaf area index, light intensity, diffuse light fraction, and leaf-air water vapor gradient. The dependence on light intensity was highly linear, in contrast to the leaf scale, and in contrast to the behavior of canopy photosynthesis. Using canopy stomatal conductance, we partitioned ET and found that evaporation in this ecosystem peaks at the time of the year when soils are driest and atmospheric vapor pressure deficit is low—because soil temperature is an important driver. As stomatal conductance impacts not only the rate of photosynthesis but also the fractionation of carbon isotopes by photosynthesis, we were also able to combine canopy stomatal conductance with CO2 isotope flux measurements in order to partition NEE. We found that: (1) canopy respiration is much less during the day than at night, likely due to the inhibition of leaf respiration by light (that is, the Kok effect), and (2) canopy photosynthetic light-use efficiency does not decline through the summer, in contrast to standard estimates. These results clarify how leaf-level physiological dynamics impact ecosystem-atmosphere gas exchange, and demonstrate the utility of combining multiple tracers to constrain the processes underlying that exchange.

  3. Honey and Radiation-Induced Stomatitis in Patients With Head and Neck Cancer.

    Science.gov (United States)

    Bahramnezhad, Fatemeh; Dehghan Nayeri, Nahid; Bassampour, Shiva Sadat; Khajeh, Mahboobeh; Asgari, Parvaneh

    2015-10-01

    Stomatitis is a common oral complication which affects 100% of patients undergoing head and neck radiotherapy. Acute stomatitis might cause failure and delay radiotherapy. Attention to mouth hygiene, particularly using mouthwash, has a fundamental importance for these patients. The current study came to addresses the effects of pure natural honey on radiation-induced stomatitis in patients with a variety of head and neck cancers. The present single-blinded nonrandomized controlled trial was conducted on 105 patients undergoing radiotherapy due to head and neck cancer at the radiation unit of Shafa hospital in Kerman, Iran, from October 2012 to March 2012. The research groups were selected by writing the names of the protocols (the mouthwashes of chamomile, honey and the common caring protocol at ward which uses water) on three cubes. The first extracted cube was related to the chamomile mouthwash (Matrica), the second to the honey mouthwash and the last cube to the water mouthwash. The first experimental group (n = 35) gurgled a solution containing 20 mL diluted honey, the second group gurgled a solution containing German chamomile, and the 35 patients in the control group were advised to gurgle 20 mL water (the ward routine). The results showed that severe stomatitis in groups of honey, chamomile and control was 0, 5.7%, and 17.6%, respectively. On the 14th day, it was 0, 0, and 17.6%, respectively. There were significant differences between the three groups regarding the severity of stomatitis in the 14th day (P < 0.001). The application of natural honey is effective in managing and preventing radiation-induced stomatitis in patients with head and neck cancers.

  4. Spatially Explicit Observations to Elucidate Simple Scalars of Forest Canopy Transpiration Across Environmental Gradients

    Science.gov (United States)

    Loranty, M. M.; Ewers, B. E.; Mackay, D. S.; Adelman, J. D.; Kruger, E. L.

    2004-12-01

    The ability to scale from point measurements to watersheds has been a key goal of hydrology. Assumptions are often made that averaging point measurements and scaling them up using a cookie-cutter or paint-by-numbers approach will capture relevant spatial gradients. To test this, we chose a site in the Chequamegon National Forest near Park Falls, WI because of its proximity to the WLEF Ameriflux tower providing kilometer scale estimates of water fluxes from a heterogeneous forest. We used a cyclic sampling design for all 144 plots of spatial measurements within a 1.5 ha area, in order to efficiently quantify spatial trends using geostatistics. Spatial data was collected for sap flux using Granier type sensors daily for ten days in 170 trees representing 7 species, including aspen, alder, and white cedar. Aspen is a dominant species in the managed forests around the WLEF tower and we have previously shown it to have the highest transpiration rates per unit leaf area of all dominant species in the area. Consequently, for this study we focused on aspen. Spatial soil moisture, vapor pressure deficit, and leaf area index were also measured periodically at the same 144 plots. We found that the semivariagram of soil moisture showed a range of 110 meters on a low soil moisture day and 80 meters on a high soil moisture day. When we quantified sap flux per unit xylem area across a 105-meter long gradient from a wetland to an upland we found no differences. However, once we scaled the sap flux measurements to the whole tree using basal area, there was more than a 100 percent increase in whole tree water use in the upland area in comparison to the wetland area. Thus, we will test the hypothesis that in the absence of moisture stress, canopy transpiration in aspen varies spatially with allometrically scaled sapwood area and leaf area and not as a function of sap flux per unit sapwood area.

  5. RIN4 functions with plasma membrane H+-ATPases to regulate stomatal apertures during pathogen attack

    DEFF Research Database (Denmark)

    Liu, Jun; Elmore, James M.; Fuglsang, Anja Thoe

    2009-01-01

    Abstract Pathogen perception by the plant innate immune system is of central importance to plant survival and productivity. The Arabidopsis protein RIN4 is a negative regulator of plant immunity. In order to identify additional proteins involved in RIN4- mediated immune signal transduction, we...... exhibit differential PM H+-ATPase activity. PM H+-ATPase activation induces stomatal opening, enabling bacteria to gain entry into the plant leaf; inactivation induces stomatal closure thus restricting bacterial invasion. The rin4 knockout line exhibited reduced PM H+-ATPase activity and, importantly, its...... apertures, inhibiting the entry of bacterial pathogens into the plant leaf during infection....

  6. Reconstructing Atmospheric CO2 Through The Paleocene-Eocene Thermal Maximum Using Stomatal Index and Stomatal Density Values From Ginkgo adiantoides

    Science.gov (United States)

    Barclay, R. S.; Wing, S. L.

    2013-12-01

    The Paleocene-Eocene Thermal Maximum (PETM) was a geologically brief interval of intense global warming 56 million years ago. It is arguably the best geological analog for a worst-case scenario of anthropogenic carbon emissions. The PETM is marked by a ~4-6‰ negative carbon isotope excursion (CIE) and extensive marine carbonate dissolution, which together are powerful evidence for a massive addition of carbon to the oceans and atmosphere. In spite of broad agreement that the PETM reflects a large carbon cycle perturbation, atmospheric concentrations of CO2 (pCO2) during the event are not well constrained. The goal of this study is to produce a high resolution reconstruction of pCO2 using stomatal frequency proxies (both stomatal index and stomatal density) before, during, and after the PETM. These proxies rely upon a genetically controlled mechanism whereby plants decrease the proportion of gas-exchange pores (stomata) in response to increased pCO2. Terrestrial sections in the Bighorn Basin, Wyoming, contain macrofossil plants with cuticle immediately bracketing the PETM, as well as dispersed plant cuticle from within the body of the CIE. These fossils allow for the first stomatal-based reconstruction of pCO2 near the Paleocene-Eocene boundary; we also use them to determine the relative timing of pCO2 change in relation to the CIE that defines the PETM. Preliminary results come from macrofossil specimens of Ginkgo adiantoides, collected from an ~200ka interval prior to the onset of the CIE (~230-30ka before), and just after the 'recovery interval' of the CIE. Stomatal index values decreased by 37% within an ~70ka time interval at least 100ka prior to the onset of the CIE. The decrease in stomatal index is interpreted as a significant increase in pCO2, and has a magnitude equivalent to the entire range of stomatal index adjustment observed in modern Ginkgo biloba during the anthropogenic CO2 rise during the last 150 years. The inferred CO2 increase prior to the

  7. Starch Biosynthesis in Guard Cells But Not in Mesophyll Cells Is Involved in CO2-Induced Stomatal Closing1[OPEN

    Science.gov (United States)

    Stephan, Aaron B.; Schroeder, Julian I.

    2016-01-01

    Starch metabolism is involved in stomatal movement regulation. However, it remains unknown whether starch-deficient mutants affect CO2-induced stomatal closing and whether starch biosynthesis in guard cells and/or mesophyll cells is rate limiting for high CO2-induced stomatal closing. Stomatal responses to [CO2] shifts and CO2 assimilation rates were compared in Arabidopsis (Arabidopsis thaliana) mutants that were either starch deficient in all plant tissues (ADP-Glc-pyrophosphorylase [ADGase]) or retain starch accumulation in guard cells but are starch deficient in mesophyll cells (plastidial phosphoglucose isomerase [pPGI]). ADGase mutants exhibited impaired CO2-induced stomatal closure, but pPGI mutants did not, showing that starch biosynthesis in guard cells but not mesophyll functions in CO2-induced stomatal closing. Nevertheless, starch-deficient ADGase mutant alleles exhibited partial CO2 responses, pointing toward a starch biosynthesis-independent component of the response that is likely mediated by anion channels. Furthermore, whole-leaf CO2 assimilation rates of both ADGase and pPGI mutants were lower upon shifts to high [CO2], but only ADGase mutants caused impairments in CO2-induced stomatal closing. These genetic analyses determine the roles of starch biosynthesis for high CO2-induced stomatal closing. PMID:27208296

  8. Promotion of stomatal opening in detached epidermis of Kalanchoe daigremontiana Hamet et Perr. by natural and synthetic cytokinins.

    Science.gov (United States)

    Jewer, P C; Incoll, L D

    1981-12-01

    The cytokinins kinetin and zeatin increased stomatal opening at 15°C in the dark by up to 50% in detached epidermis of the CAM plant Kalanchoe daigremontiana. Stomata opened maximally following incubation with 10 mmol m(-3) cytokinin. This study extends the range of species in which exogenous cytokinins promote stomatal opening.

  9. Contrasting hypoxia tolerance and adaptation in Malus species is linked to differences in stomatal behavior and photosynthesis.

    Science.gov (United States)

    Bai, Tuanhui; Li, Cuiying; Li, Chao; Liang, Dong; Ma, Fengwang

    2013-04-01

    We examined the potential differences in tolerance to hypoxia by two species of apple rootstocks. Stomatal behavior and photosynthesis were compared between Malus sieversii and Malus hupehensis. Plants were hydroponically grown for 15 days in normoxic or hypoxic nutrient solutions. Those of M. sieversii showed much greater sensitivity, with exposure to hypoxia resulting in higher leaf concentrations of abscisic acid (ABA) that prompted stomatal closure. Compared with the control plants of that species, stomatal density was greater in both new and mature leaves under stress conditions. In contrast, stomatal density was significantly decreased in leaves from M. hupehensis, while stomatal length was unaffected. Under stress, the net photosynthetic rate, stomatal conductance and chlorophyll contents were markedly reduced in M. sieversii. The relatively hypoxia-tolerant genotype M. hupehensis, however, showed only minor changes in net photosynthesis or chlorophyll content, and only a slight decrease in stomatal conductance due to such treatment. Therefore, we conclude that the more tolerant M. hupehensis utilizes a better protective mechanism for retaining higher photosynthetic capacity than does the hypoxia-sensitive M. sieversii. Moreover, this contrast in tolerance and adaptation to stress is linked to differences in their stomatal behavior, photosynthetic capacity and possibly their patterns of native distribution. Copyright © Physiologia Plantarum 2012.

  10. [Mechanism of resistance of a clone isolated from L cells chronically infected with the virus of vesicular stomatitis].

    Science.gov (United States)

    Sovetova, G P; Zhdanov, V M

    1976-01-01

    The results of the study on antiviral immunity acquired by L cells to vesicular stomatitis virus are presented. We failed to detect the presence of the indicator virus in the resistant culture by means of virological, electron microscopic or cytochemical methods. Molecular hybrization experiments demonstrated the lack in the nuclear DNA of sequences homologous to vesicular stomatitis virus RNA.

  11. Stomatal kinetics and photosynthetic gas exchange along a continuum of isohydric to anisohydric regulation of plant water status

    Science.gov (United States)

    Frederick C. Meinzer; Duncan D. Smith; David R. Woodruff; Danielle E. Marias; Katherine A. McCulloh; Ava R. Howard; Alicia L. Magedman

    2017-01-01

    Species’ differences in the stringency of stomatal control of plant water potential represent a continuum of isohydric to anisohydric behaviours. However, little is known about how quasi-steady-state stomatal regulation of water potential may relate to dynamic behaviour of stomata and photosynthetic gas exchange in species operating at different positions along this...

  12. Differential effects of elevated air humidity on stomatal closing ability of Kalanchoë blossfeldiana between the C

    NARCIS (Netherlands)

    Fanourakis, Dimitrios; Hyldgaard, Benita; Gebraegziabher, Habtamu; Bouranis, Dimitris; Körner, Oliver; Nielsen, Kai Lønne; Ottosen, Carl-Otto

    2017-01-01

    High relative air humidity (RH ≥ 85%) impairs stomatal functionality, attenuating plant capacity to cope with abiotic stress. Previous studies were limited to C3 species, so the RH effect on stomatal physiology of CAM plants remains unexplored. We addressed the topic through

  13. Optimizing stomatal conductance for maximum carbon gain under water stress: A meta-analysis across plant functional types and climates

    Science.gov (United States)

    Stomatal responses to environmental variables, in particular atmospheric CO2 concentration and soil water status, are needed for quantifying the controls on carbon and water exchanges between plants and the atmosphere. Building on previous leaf-scale gas exchange models and stomatal optimality theor...

  14. Biophysical controls on canopy transpiration in a black locust ( Robinia pseudoacacia ) plantation on the semi-arid Loess Plateau, China

    Science.gov (United States)

    Lei Jiao; Nan Lu; Ge Sun; Eric J. Ward; Bojie Fu

    2015-01-01

    In the semi-arid Loess Plateau of China, black locust (Robinia pseudoacacia) was widely planted for soil conservation and afforestation purposes during the past three decades. Investigating biophysical controls on canopy transpiration (Ec) of the plantations is essential to understanding the effects of afforestation on watershed hydrology and regional water resources....

  15. Advances in the two-source energy balance model: Partioning of evaporation and transpiration for row crops for cotton

    Science.gov (United States)

    Accurate partitioning of the evaporation (E) and transpiration (T) components of evapotranspiration (ET) in remote sensing models is important for evaluating strategies aimed at increasing crop water productivity. The two-source energy balance (TSEB) model solves the energy balance of the soil-plant...

  16. Quantifying structural and physiological controls on variation in canopy transpiration among planted pine and hardwood species in the southern Appalachians

    Science.gov (United States)

    Chelcy R. Ford; Robert M. Hubbard; James M. Vose

    2010-01-01

    Recent studies have shown that planted pine stands exhibit higher evapotranspiration (ET) and are more sensitive to climatic conditions compared with hardwood stands. Whether this is due to management and stand effects, biological effects or their interaction is poorly understood. We estimated growing season canopy- and sap flux-scaled leaf-level transpiration (Ec and...

  17. Comparative measurements of transpiration an canopy conductance in two mixed deciduous woodlands differing in structure and species composition

    DEFF Research Database (Denmark)

    Herbst, Mathias; Rosier, Paul T.W.; Morecroft, Michael D.

    2008-01-01

    a continuous hazel (Corylus avellana L.) understory. Wytham Woods, which had an LAI of 3.6, was dominated by ash (Fraxinus excelsior L.) and sycamore (Acer pseudoplatanus L.) and had only a sparse understory. Annual canopy transpiration was 367 mm for Grimsbury Wood and 397 mm for Wytham Woods. These values...

  18. Controls on stand transpiration and soil water utilization along a tree density gradient in a Neotropical savanna

    Science.gov (United States)

    Sandra J. Bucci; Fabian G. Scholz; Guillermo Goldstein; William A. Hoffmann; Frederick C. Meinzer; Augusto C. Franco; Thomas Giambelluca; Fernando Miralles-Wilhelm

    2008-01-01

    Environmental controls of stand-level tree transpiration (E) and seasonal patterns of soil water utilization were studied in five central Brazilian savanna (Cerrado) sites differing in tree density. Tree density of Cerrado vegetation in the study area consistently changes along topographic gradients from ~1,000 trees ha-1 in open savannas (campo...

  19. Plant water relations as affected by osmotic potential of the nutrient solution and potential transpiration in tomato (Lycopersicon esculentum Mill.)

    NARCIS (Netherlands)

    Li, Y.L.; Marcelis, L.F.M.; Stanghellini, C.

    2004-01-01

    The hypothesis that water flow into tomato fruits is affected similarly by osmotic potential of the nutrient solution and potential transpiration (shoot environment) via their effects on stem water potential, was tested through experiments carried out in two glasshouses where climate was controlled

  20. Effects of above- and below-ground competition from shrubs on photosynthesis, transpiration and growth in Quercus robur L

    Science.gov (United States)

    Anna M. Jensen; Magnus Lof; Emile S. Gardiner

    2011-01-01

    For a tree seedling to successfully establish in dense shrubbery, it must maintain function under heterogeneous resource availability. We evaluated leaf-level acclimation in photosynthetic capacity, seedling-level transpiration, and seedling morphology and growth to gain an understanding of the effects of above- and below-ground competition on Quercus robur seedlings....

  1. High atmospheric demand for water can limit forest carbon uptake and transpiration as severely as dry soil

    Science.gov (United States)

    Benjamin N. Sulman; Daniel Tyler Roman; Koong Yi; Lixin Wang; Richard P. Phillips; Kimberly A. Novick

    2016-01-01

    When stressed by low soil water content (SWC) or high vapor pressure deficit (VPD), plants close stomata, reducing transpiration and photosynthesis. However, it has historically been difficult to disentangle the magnitudes of VPD compared to SWC limitations on ecosystem-scale fluxes. We used a 13 year record of eddy covariance measurements from a forest in south...

  2. Advances in the two-source energy balance model:Partioning of evaporation and transpiration for row crops

    Science.gov (United States)

    Accurate partitioning of the evaporation (E) and transpiration (T) components of evapotranspiration (ET) in remote sensing models is important for evaluating strategies aimed at increasing crop water productivity. The two-source energy balance (TSEB) model solves the energy balance of the soil-plant...

  3. Stomatal lock-open, a consequence of epidermal cell death, follows transient suppression of stomatal opening in barley attacked by Blumeria graminis.

    Science.gov (United States)

    Prats, Elena; Gay, Alan P; Mur, Luis A J; Thomas, Barry J; Carver, Timothy L W

    2006-01-01

    Blumeria graminis f.sp. hordei (Bgh) attack disrupted stomatal behaviour, and hence leaf water conductance (g(l)), in barley genotypes Pallas and Risø-S (susceptible), P01 (with Mla1 conditioning a hypersensitive response; HR), and P22 and Risø-R (with mlo5 conditioning papilla-based penetration resistance). Inoculation caused some stomatal closure well before the fungus attempted infection. Coinciding with epidermal cell penetration, stomatal opening in light was also impeded, although stomata of susceptible and mlo5 lines remained largely able to close in darkness. Following infection, in susceptible lines stomata closed in darkness but opening in light was persistently impeded. In Risø-R, stomata recovered nearly complete function by approximately 30 h after inoculation, i.e. after penetration resistance was accomplished. In P01, stomata became locked open and unable to close in darkness shortly after epidermal cells died due to HR. In the P22 background, mlo5 penetration resistance was often followed by consequential death of attacked cells, and here too stomata became locked open, but not until approximately 24 h after pathogen attack had ceased. The influence of epidermal cell death was localized, and only affected stomata within one or two cells distance. These stomata were unable to close not only in darkness but also after application of abscisic acid and in wilted leaves suffering drought. Thus, resistance to Bgh based on HR or associated with cell death may have previously unsuspected negative consequences for the physiological health of apparently 'disease-free' plants. The results are discussed in relation to the control of stomatal aperture in barley by epidermal cells.

  4. Impaired Stomatal Control Is Associated with Reduced Photosynthetic Physiology in Crop Species Grown at Elevated [CO2

    Science.gov (United States)

    Haworth, Matthew; Killi, Dilek; Materassi, Alessandro; Raschi, Antonio; Centritto, Mauro

    2016-01-01

    Physiological control of stomatal conductance (Gs) permits plants to balance CO2-uptake for photosynthesis (PN) against water-loss, so optimizing water use efficiency (WUE). An increase in the atmospheric concentration of carbon dioxide ([CO2]) will result in a stimulation of PN and reduction of Gs in many plants, enhancing carbon gain while reducing water-loss. It has also been hypothesized that the increase in WUE associated with lower Gs at elevated [CO2] would reduce the negative impacts of drought on many crops. Despite the large number of CO2-enrichment studies to date, there is relatively little information regarding the effect of elevated [CO2] on stomatal control. Five crop species with active physiological stomatal behavior were grown at ambient (400 ppm) and elevated (2000 ppm) [CO2]. We investigated the relationship between stomatal function, stomatal size, and photosynthetic capacity in the five species, and then assessed the mechanistic effect of elevated [CO2] on photosynthetic physiology, stomatal sensitivity to [CO2] and the effectiveness of stomatal closure to darkness. We observed positive relationships between the speed of stomatal response and the maximum rates of PN and Gs sustained by the plants; indicative of close co-ordination of stomatal behavior and PN. In contrast to previous studies we did not observe a negative relationship between speed of stomatal response and stomatal size. The sensitivity of stomata to [CO2] declined with the ribulose-1,5-bisphosphate limited rate of PN at elevated [CO2]. The effectiveness of stomatal closure was also impaired at high [CO2]. Growth at elevated [CO2] did not affect the performance of photosystem II indicating that high [CO2] had not induced damage to the photosynthetic physiology, and suggesting that photosynthetic control of Gs is either directly impaired at high [CO2], sensing/signaling of environmental change is disrupted or elevated [CO2] causes some physical effect that constrains stomatal

  5. Impaired stomatal control is associated with reduced photosynthetic physiology in crop species grown at elevated [CO2

    Directory of Open Access Journals (Sweden)

    Matthew Haworth

    2016-10-01

    Full Text Available Physiological control of stomatal conductance (Gs permits plants to balance CO2-uptake for photosynthesis (PN against water-loss, so optimising water use efficiency (WUE. An increase in the atmospheric concentration of carbon dioxide ([CO2] will result in a stimulation of PN and reduction of Gs in many plants, enhancing carbon gain while reducing water-loss. It has also been hypothesised that the increase in WUE associated with lower Gs at elevated [CO2] would reduce the negative impacts of drought on many crops. Despite the large number of CO2-enrichment studies to date, there is relatively little information regarding the effect of elevated [CO2] on stomatal control. Five crop species with active physiological stomatal behaviour were grown at ambient (400 ppm and elevated (2000 ppm [CO2]. We investigated the relationship between stomatal function, stomatal size and photosynthetic capacity in the five species, and then assessed the mechanistic effect of elevated [CO2] on photosynthetic physiology, stomatal sensitivity to [CO2] and the effectiveness of stomatal closure to darkness. We observed positive relationships between the speed of stomatal response and the maximum rates of PN and Gs sustained by the plants; indicative of close co-ordination of stomatal behaviour and PN. In contrast to previous studies we did not observe a negative relationship between speed of stomatal response and stomatal size. The sensitivity of stomata to [CO2] declined with the ribulose-1,5-bisphosphate limited rate of PN at elevated [CO2]. The effectiveness of stomatal closure was also impaired at high [CO2]. Growth at elevated [CO2] did not affect the performance of photosystem II indicating that high [CO2] had not induced damage to the photosynthetic physiology, and suggesting that photosynthetic control of Gs is either directly impaired at high [CO2], sensing/signalling of environmental change is disrupted or elevated [CO2] causes some physical effect that

  6. Aquaporin Expression and Water Transport Pathways inside Leaves Are Affected by Nitrogen Supply through Transpiration in Rice Plants

    Directory of Open Access Journals (Sweden)

    Lei Ding

    2018-01-01

    Full Text Available The photosynthetic rate increases under high-N supply, resulting in a large CO2 transport conductance in mesophyll cells. It is less known that water movement is affected by nitrogen supply in leaves. This study investigated whether the expression of aquaporin and water transport were affected by low-N (0.7 mM and high-N (7 mM concentrations in the hydroponic culture of four rice varieties: (1 Shanyou 63 (SY63, a hybrid variant of the indica species; (2 Yangdao 6 (YD6, a variant of indica species; (3 Zhendao 11 (ZD11, a hybrid variant of japonica species; and (4 Jiuyou 418 (JY418, another hybrid of the japonica species. Both the photosynthetic and transpiration rate were increased by the high-N supply in the four varieties. The expressions of aquaporins, plasma membrane intrinsic proteins (PIPs, and tonoplast membrane intrinsic protein (TIP were higher in high-N than low-N leaves, except in SY63. Leaf hydraulic conductance (Kleaf was lower in high-N than low-N leaves in SY63, while Kleaf increased under high-N supply in the YD6 variant. Negative correlations were observed between the expression of aquaporin and the transpiration rate in different varieties. Moreover, there was a significant negative correlation between transpiration rate and intercellular air space. In conclusion, the change in expression of aquaporins could affect Kleaf and transpiration. A feedback effect of transpiration would regulate aquaporin expression. The present results imply a coordination of gas exchange with leaf hydraulic conductance.

  7. Stomatal Conductance, Plant Species Distribution, and an Exploration of Rhizosphere Microbes and Mycorrhizae at a Deliberately Leakimg Experimental Carbon Sequestration Field (ZERT)

    Science.gov (United States)

    Sharma, B.; Apple, M. E.; Morales, S.; Zhou, X.; Holben, B.; Olson, J.; Prince, J.; Dobeck, L.; Cunningham, A. B.; Spangler, L.

    2010-12-01

    One measure to reduce atmospheric CO2 is to sequester it in deep geological formations. Rapid surface detection of any CO2 leakage is crucial. CO2 leakage rapidly affects vegetation above sequestration fields. Plant responses to high CO2 are valuable tools in surface detection of leaking CO2. The Zero Emission Research Technology (ZERT) site in Bozeman, MT is an experimental field for surface detection of CO2 where 0.15 ton/day of CO2 was released (7/19- 8/15/2010) from a 100m horizontal injection well, HIW, 1.5 m underground with deliberate leaks of CO2 at intervals, and from a vertical injector, VI, (6/3-6/24/2010). The vegetation includes Taraxacum officinale (Dandelion), Dactylis glomerata (Orchard Grass), and other herbaceous plants. We collected soil and roots 1, 3 and 5 m from the VI to determine the responses of mycorrhizal fungi and rhizosphere microbes to high CO2. Mycorrhizal fungi obtain C from root exudates, increase N and P availability, and reduce desiccation, while prokaryotic rhizosphere microbes fix atmospheric N and will be examined for abundance and expression of carbon and nitrogen cycling genes. We are quantifying mycorrhizal colonization and the proportion of spores, hyphae, and arbuscules in vesicular-arbuscular mycorrhizae (VAM) in cleared and stained roots. Stomatal conductance is an important measure of CO2 uptake and water loss via transpiration. We used a porometer (5-40°C, 0-90% RH, Decagon) to measure stomatal conductivity in dandelion and orchard grass at 1, 3, and 5 m from the VI and along a transect perpendicular to the HIW. Dandelion conductance was highest close to the VI and almost consistently higher close to hot spots (circular regions with maximum CO2 and leaf dieback) at the HIW, with 23.2 mmol/m2/s proximal to the hot spot, and 10.8 mmol/m2/s distally. Average conductance in grass (50.3 mmol/m2/s) was higher than in dandelion, but grass did not have high conductance near hot spots. Stomata generally close at elevated CO2

  8. In the light of stomatal opening: new insights into 'the Watergate'.

    Science.gov (United States)

    Roelfsema, M Rob G; Hedrich, Rainer

    2005-09-01

    Stomata can be regarded as hydraulically driven valves in the leaf surface, which open to allow CO2 uptake and close to prevent excessive loss of water. Movement of these 'Watergates' is regulated by environmental conditions, such as light, CO2 and humidity. Guard cells can sense environmental conditions and function as motor cells within the stomatal complex. Stomatal movement results from the transport of K+ salts across the guard cell membranes. In this review, we discuss the biophysical principles and mechanisms of stomatal movement and relate these to ion transport at the plasma membrane and vacuolar membrane. Studies with isolated guard cells, combined with recordings on single guard cells in intact plants, revealed that light stimulates stomatal opening via blue light-specific and photosynthetic-active radiation-dependent pathways. In addition, guard cells sense changes in air humidity and the water status of distant tissues via the stress hormone abscisic acid (ABA). Guard cells thus provide an excellent system to study cross-talk, as multiple signaling pathways induce both short- and long-term responses in these sensory cells.

  9. Stomatal vs. genome size in angiosperms: the somatic tail wagging the genomic dog?

    NARCIS (Netherlands)

    Hodgson, J.G.; Sharafi, M.; Jalili, A.; Diaz, S.; Montserrat-Marti, G.; Palmer, C.; Cerabolini, B.; Pierce, S.; Hamzehee, B.; Asri, Y.; Jamzad, Z.; Wilson, P.; Zarrinkamar, F.; Raven, J.; Band, S.R.; Basconcelo, S.; Bogard, A.; Carter, G.; Charles, M.; Castro-Diez, P.; Cornelissen, J.H.C.; Funes, G.; Jones, M.; Khoshnevis, M.; Perez-Harguindeguy, N.; Perez-Rontome, M.C.; Shirvany, F.A.; Vendramini, F.; Yazdani, S.; Abbas-Azimi, R.; Boustani, S.; Dehghan, M.; Hynd, F.A.; Kowsary, E.; Kazemi-Saeed, F.; Siavash, B.; Villar-Salvador, P.; Cragie, R.; Naqinezhad, A.; Romo-Diez, A.; De Torres Espuny, L.; Simmons, E.

    2010-01-01

    Background and Aims Genome size is a function, and the product, of cell volume. As such it is contingent on ecological circumstance. The nature of 'this ecological circumstance' is, however, hotly debated. Here, we investigate for angiosperms whether stomatal size may be this 'missing link': the

  10. Stomatal conductance, canopy temperature, and leaf area index estimation using remote sensing and OBIA techniques

    Science.gov (United States)

    S. Panda; D.M. Amatya; G. Hoogenboom

    2014-01-01

    Remotely sensed images including LANDSAT, SPOT, NAIP orthoimagery, and LiDAR and relevant processing tools can be used to predict plant stomatal conductance (gs), leaf area index (LAI), and canopy temperature, vegetation density, albedo, and soil moisture using vegetation indices like normalized difference vegetation index (NDVI) or soil adjusted...

  11. Oral hygiene habits, denture plaque, presence of yeasts and stomatitis in institutionalised elderly in Lothian, Scotland

    DEFF Research Database (Denmark)

    Schou, L; Wight, C; Cumming, C

    1987-01-01

    The purpose of the present study was to examine the relation between oral hygiene habits, denture plaque, presence of yeasts and stomatitis in institutionalised elderly. A sample of 201 residents, 48-99 yr of age (mean age 82 yr), was selected from four different institutions in Lothian, Scotland...

  12. Using Plant Temperature to Evaluate the Response of Stomatal Conductance to Soil Moisture Deficit

    Directory of Open Access Journals (Sweden)

    Ming-Han Yu

    2015-10-01

    Full Text Available Plant temperature is an indicator of stomatal conductance, which reflects soil moisture stresses. We explored the relationship between plant temperature and soil moisture to optimize irrigation schedules in a water-stress experiment using Firmiana platanifolia (L. f. Marsili in an incubator. Canopy temperature, leaf temperature, and stomatal conductance were measured using thermal imaging and a porometer. The results indicated that (1 stomatal conductance decreased with declines in soil moisture, and reflected average canopy temperature; (2 the variation of the leaf temperature distribution was a reliable indicator of soil moisture stress, and the temperature distribution in severely water-stressed leaves exhibited greater spatial variation than that in the presence of sufficient irrigation; (3 thermal indices (Ig and crop water stress index (CWSI were theoretically proportional to stomatal conductance (gs, Ig was certified to have linearity relationship with gs and CWSI have a logarithmic relationship with gs, and both of the two indices can be used to estimate soil moisture; and (4 thermal imaging data can reflect water status irrespective of long-term water scarcity or lack of sudden rainfall. This study applied thermal imaging methods to monitor plants and develop adaptable irrigation scheduling, which are important for the formulation of effective and economical agriculture and forestry policy.

  13. Comparison of arabidopsis stomatal density mutants indicates variation in water stress responses and potential epistatic effects

    Science.gov (United States)

    Shaneka S. Lawson; Paula M. Pijut; Charles H. Michler

    2014-01-01

    Recent physiological analysis of Arabidopsis stomatal density (SD) mutants indicated that SD was not the major factor controlling aboveground biomass accumulation. Despite the general theory that plants with fewer stomata have limited biomass acquisition capabilities, epf1 and several other Arabidopsis mutants varied significantly in leaf fresh...

  14. Bovine lactoferrin and piroxicam as an adjunct treatment for lymphocytic-plasmacytic gingivitis stomatitis in cats.

    Science.gov (United States)

    Hung, Yi-Ping; Yang, Yi-Ping; Wang, Hsien-Chi; Liao, Jiunn-Wang; Hsu, Wei-Li; Chang, Chao-Chin; Chang, Shih-Chieh

    2014-10-01

    Feline lymphocytic-plasmacytic gingivitis/stomatitis (LPGS) or caudal stomatitis is an inflammatory disease that causes painfully erosive lesions and proliferations of the oral mucosa. The disease is difficult to cure and can affect cats at an early age, resulting in lifetime therapy. In this study, a new treatment using a combination of bovine lactoferrin (bLf) oral spray and oral piroxicam was investigated using a randomized double-blinded clinical trial in 13 cats with caudal stomatitis. Oral lesion grading and scoring of clinical signs were conducted during and after the trial to assess treatment outcome. Oral mucosal biopsies were used to evaluate histological changes during and after treatment. Clinical signs were significantly improved in 77% of the cats. In a 4-week study, clinical signs were considerably ameliorated by oral piroxicam during the first 2 weeks. In a 12-week study, the combined bLf oral spray and piroxicam, when compared with piroxicam alone, exhibited an enhanced effect that reduced the severity of the oral lesions (P = 0.059), while also significantly improving clinical signs (P piroxicam was safe and might be used to decrease the clinical signs of caudal stomatitis in cats. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  15. Vesicular Stomatitis Virus Infection Promotes Immune Evasion by Preventing NKG2D-Ligand Surface Expression

    DEFF Research Database (Denmark)

    Jensen, Helle; Andresen, Lars; Nielsen, Jens

    2011-01-01

    Vesicular stomatitis virus (VSV) has recently gained attention for its oncolytic ability in cancer treatment. Initially, we hypothesized that VSV infection could increase immune recognition of cancer cells through induction of the immune stimulatory NKG2D-ligands. Here we show that VSV infection ...

  16. Stomatal response characteristics as affected by long-term elevated humidity levels

    NARCIS (Netherlands)

    Fanourakis, D.

    2011-01-01

    Restriction of leaf water loss, by stomatal closure, is decisive for plant survival, especially under conditions of water deficit. This sensitivity of stomata to low water potential is attenuated by high relative air humidity (RH ≥ 85%) during growth, which impedes the plant’s ability to

  17. Clinical evaluation of the essential oil of "Satureja Hortensis" for the treatment of denture stomatitis

    Directory of Open Access Journals (Sweden)

    Ali Mohammad Sabzghabaee

    2012-01-01

    Full Text Available Background: The prevalence of denture stomatitis has been shown to vary from 15 to 65% in complete denture wearers. Satureja hortensis L. has been considered to have antinociceptive, anti-inflammatory, antifungal and antimicrobial activities in vitro and exhibits strong inhibitory effect on the growth of periodontal bacteria. The aim of this study was to evaluate the efficacy of a 1% gel formulation of S. hortensis essential oil for the treatment of denture stomatitis. Materials and Methods: A randomized, controlled clinical trial study was conducted on 80 patients (mean age 62.91±7.34 in two parallel groups treated either with S. hortensis essential oil 1% gel or placebo applied two times daily for two weeks. Denture stomatitis was diagnosed by clinical examination and paraclinical confirmation with sampling the palatal mucosa for Candida albicans. Data were analyzed using Chi-squared or Student′s t tests. Results: The erythematous lesions of palatal area were significantly reduced (P<0.0001 in the treatment group who applied 1% topical gel of S. hortensis essential oil and Candida colonies count were reduced significantly (P=0.001. Conclusion: Topical application of the essential oil of S. hortensis could be considered as an effective agent for the treatment of denture stomatitis.

  18. Stomatal and pavement cell density linked to leaf internal CO2 concentration

    Czech Academy of Sciences Publication Activity Database

    Šantrůček, Jiří; Vráblová, M.; Šimková, Marie; Hronková, Marie; Drtinová, M.; Květoň, J.; Vrábl, D.; Kubásek, J.; Macková, J.; Wiesnerová, Dana; Neuwithová, J.; Schreiber, L.

    2014-01-01

    Roč. 114, č. 2 (2014), s. 191-202 ISSN 0305-7364 R&D Projects: GA ČR(CZ) GAP501/12/1261 Institutional support: RVO:60077344 Keywords : Stomatal density * Stomata development * Pavement cells Subject RIV: CE - Biochemistry Impact factor: 3.654, year: 2014

  19. Stomatal response characteristics as affected by long-term elevated humidity levels

    NARCIS (Netherlands)

    Fanourakis, D.

    2011-01-01

    Restriction of leaf water loss, by stomatal closure, is decisive for plant survival, especially under conditions of water deficit. This sensitivity of stomata to low water potential is attenuated by high relative air humidity (RH ≥ 85%) during growth, which impedes the plant’s ability to survive

  20. Effect of Relative Air Himidity on the Stomatal Functionality in Fully Developed Leaves

    NARCIS (Netherlands)

    Fanourakis, D.; Matkaris, N.; Heuvelink, E.; Carvalho, S.M.P.

    2010-01-01

    Several studies have shown that stomata developed under long-term high relative air humidity (RH =85%) are malfunctional, resulting in a poor control of water loss. Yet, little is known about the dynamics of stomatal adaptation to moderate RH, and the possibilities to improve or reverse the

  1. Dynamics of adaptation of stomatal behaviour to moderate or high relative air humidity in Tradescantia virginiana

    NARCIS (Netherlands)

    Rezaei Nejad, A.; Meeteren, van U.

    2008-01-01

    Chlorophyll fluorescence imaging was used to measure stomatal closure in response to desiccation of Tradescantia virginiana leaves grown under high (90%) and moderate (55%) relative humidities (RHs), or transferred between these humidities. Stomata in leaves grown at high RH were less responsive to

  2. Stomatal design principles for gas exchange in synthetic and real leaves

    Science.gov (United States)

    Jensen, Kaare H.; Haaning, Katrine; Boyce, C. Kevin; Zwieniecki, Maciej

    2016-11-01

    Stomata are portals in plant leaves that control gas exchange for photosynthesis, a process fundamental to life on Earth. Gas fluxes and plant productivity depend on external factors such as light, water, and CO2 availability and on geometric properties of the stomata pores. The link between stomata geometry and environmental factors have informed a wide range of scientific fields - from agriculture to climate science, where observed variations in stomata size and density is used to infer prehistoric atmospheric CO2 content. However, the physical mechanisms and design principles responsible for major trends in stomatal patterning, are not well understood. Here we use a combination of biomimetic experiments and theory to rationalize the observed changes in stomatal geometry. We show that the observed correlations between stomatal size and density are consistent with the hypothesis that plants favor efficient use of space and maximum control of dynamic gas conductivity, and - surprisingly - that the capacity for gas exchange in plants has remained constant over at least the last 325 million years. Our analysis provides a new measure to gauge the relative performance of species based on their stomatal characteristics. Supported by the Carlsberg Foundation (2013-01-0449), VILLUM FONDEN (13166) and the National Science Foundation (EAR-1024041).

  3. Several developmental and morphogenetic factors govern the evolution of stomatal patterning in land plants.

    Science.gov (United States)

    Rudall, Paula J; Hilton, Jason; Bateman, Richard M

    2013-11-01

    We evaluate stomatal development in terms of its primary morphogenetic factors and place it in a phylogenetic context, including clarification of the contrasting specialist terms that are used by different sets of researchers. The genetic and structural bases for stomatal development are well conserved and increasingly well understood in extant taxa, but many phylogenetically crucial plant lineages are known only from fossils, in which it is problematic to infer development. For example, specialized lateral subsidiary cells that occur adjacent to the guard cells in some taxa can be derived either from the same cell lineage as the guard cells or from an adjacent cell file. A potentially key factor in land-plant evolution is the presence (mesogenous type) or absence (perigenous type) of at least one asymmetric division in the cell lineage leading to the guard-mother cell. However, the question whether perigenous or mesogenous development is ancestral in land plants cannot yet be answered definitively based on existing data. Establishment of 'fossil fingerprints' as developmental markers is critical for understanding the evolution of stomatal patterning. Long cell-short cell alternation in the developing leaf epidermis indicates that the stomata are derived from an asymmetric mitosis. Other potential developmental markers include nonrandom stomatal orientation and a range of variation in relative sizes of epidermal cells. Records of occasional giant stomata in fossil bennettites could indicate development of a similar type to early-divergent angiosperms. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  4. Land plants acquired active stomatal control early in their evolutionary history.

    Science.gov (United States)

    Ruszala, Elizabeth M; Beerling, David J; Franks, Peter J; Chater, Caspar; Casson, Stuart A; Gray, Julie E; Hetherington, Alistair M

    2011-06-21

    Stomata are pores that regulate plant gas exchange [1]. They evolved more than 400 million years ago [2, 3], but the origin of their active physiological responses to endogenous and environmental cues is unclear [2-6]. Recent research suggests that the stomata of lycophytes and ferns lack pore closure responses to abscisic acid (ABA) and CO(2). This evidence led to the hypothesis that a fundamental transition from passive to active control of plant water balance occurred after the divergence of ferns 360 million years ago [7, 8]. Here we show that stomatal responses of the lycophyte Selaginella [9] to ABA and CO(2) are directly comparable to those of the flowering plant Arabidopsis [10]. Furthermore, we show that the underlying intracellular signaling pathways responsible for stomatal aperture control are similar in both basal and modern vascular plant lineages. Our evidence challenges the hypothesis that acquisition of active stomatal control of plant carbon and water balance represents a critical turning point in land plant evolution [7, 8]. Instead, we suggest that the critical evolutionary development is represented by the innovation of stomata themselves and that physiologically active stomatal control originated at least as far back as the emergence of the lycophytes (circa 420 million years ago) [11]. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. A note on stomatal types and crystals in the leaves of Melastomataceae

    NARCIS (Netherlands)

    Baas, P.

    1981-01-01

    Original data on leaf crystals and stomatal types in 25 genera of Melastomataceae are presented, and discussed with reference to the classification of the family as modified by Van Vliet et al. (1981, this issue). The heterogeneity of the abolished subfamily Astronioideae is confirmed and a

  6. Early evolutionary acquisition of stomatal control and development gene signalling networks.

    Science.gov (United States)

    Chater, Caspar; Gray, Julie E; Beerling, David J

    2013-10-01

    Fossil stomata of early vascular land plants date back over 418 million years and exhibit properties suggesting that they were operational, including differentially thickened guard cells and sub-stomatal chambers. Molecular studies on basal land plant groups (bryophytes and lycophytes) provide insight into the core genes involved in sensing and translating changes in the drought hormone abscisic acid (ABA), light and concentration of CO2 into changes in stomatal aperture. These studies indicate that early land plants probably possessed the genetic tool kits for stomata to actively respond to environmental/endogenous cues. With these ancestral molecular genetic tool kits in place, stomatal regulation of plant carbon and water relations may have became progressively more effective as hydraulic systems evolved in seed plant lineages. Gene expression and cross-species gene complementation studies suggest that the pathway regulating stomatal fate may also have been conserved across land plant evolution. This emerging area offers a fascinating glimpse into the potential genetic tool kits used by the earliest vascular land plants to build and operate the stomata preserved in the fossil record. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Nitric oxide in guard cells as an important secondary messenger during stomatal closure

    Directory of Open Access Journals (Sweden)

    Gunja eGayatri

    2013-10-01

    Full Text Available he modulation of guard cell function is the basis of stomatal closure, essential for optimizing water use and CO2 uptake by leaves. Nitric oxide (NO in guard cells plays a very important role as a secondary messenger during stomatal closure induced by effectors, including hormones. For example, exposure to abscisic acid (ABA triggers a marked increase in NO of guard cells, well before stomatal closure. In guard cells of multiple species, like Arabidopsis, Vicia and pea, exposure to ABA or methyl jasmonate or even microbial elicitors (e.g. chitosan induces production of NO as well as reactive oxygen species (ROS. The role of NO in stomatal closure has been confirmed by using NO donors (e.g. SNP and NO scavengers (like cPTIO and inhibitors of NOS (L-NAME or NR (tungstate. Two enzymes: a L-NAME-sensitive, nitric oxide synthase (NOS-like enzyme and a tungstate-sensitive nitrate reductase (NR, can mediate ABA-induced NO rise in guard cells. However, the existence of true NOS in plant tissues and its role in guard cell NO-production are still a matter of intense debate. Guard cell signal transduction leading to stomatal closure involves the participation of several components, besides NO, such as cytosolic pH, ROS, free Ca2+ and phospholipids. Use of fluorescent dyes has revealed that the rise in NO of guard cells occurs after the increase in cytoplasmic pH and ROS. The rise in NO causes an elevation in cytosolic free Ca2+ and promotes the efflux of cations as well as anions from guard cells. Stomatal guard cells have become a model system to study the signalling cascade mechanisms in plants, particularly with NO as a dominant component. The interrelationships and interactions of NO with cytosolic pH, ROS, and free Ca2+ are quite complex and need further detailed examination. While assessing critically the available literature, the present review projects possible areas of further work related to NO-action in stomatal guard cells.

  8. Toward an improved understanding of the role of transpiration in critical zone dynamics

    Science.gov (United States)

    Mitra, B.; Papuga, S. A.

    2012-12-01

    Evapotranspiration (ET) is an important component of the total water balance across any ecosystem. In subalpine mixed-conifer ecosystems, transpiration (T) often dominates the total water flux and therefore improved understanding of T is critical for accurate assessment of catchment water balance and for understanding of the processes that governs the complex dynamics across critical zone (CZ). The interaction between T and plant vegetation not only modulates soil water balance but also influences water transit time and hydrochemical flux - key factors in our understanding of how the CZ evolves and responds. Unlike an eddy covariance system which provides only an integrated ET flux from an ecosystem, a sap flow system can provide an estimate of the T flux from the ecosystem. By isolating T, the ecohydrological drivers of this major water loss from the CZ can be identified. Still, the species composition of mixed-conifer ecosystems vary and the drivers of T associated with each species are expected to be different. Therefore, accurate quantification of T from a mixed-conifer requires knowledge of the unique transpiration dynamics of each of the tree species. Here, we installed a sap flow system within two mixed-conifer study sites of the Jemez River Basin - Santa Catalina Mountains Critical Zone Observatory (JRB - SCM CZO). At both sites, we identified the dominant tree species and installed sap flow sensors on healthy representatives for each of those species. At the JRB CZO site, sap sensors were installed in fir (4) and spruce (4) trees; at the SCM CZO site, sap sensors were installed at white fir (4) and maple (4) and one dead tree. Meteorological data as well as soil temperature (Ts) and soil moisture (θ) at multiple depths were also collected from each of the two sites. Preliminary analysis of two years of sap flux rate at JRB - SCM CZO shows that the environmental drivers of fir, spruce, and maple are different and also vary throughout the year. For JRB fir

  9. Application of thermography for monitoring stomatal conductance of Coffea arabica under different shading systems.

    Science.gov (United States)

    Craparo, A C W; Steppe, K; Van Asten, P J A; Läderach, P; Jassogne, L T P; Grab, S W

    2017-12-31

    Stomatal regulation is a key process in the physiology of Coffea arabica (C. arabica). Intrinsically linked to photosynthesis and water relations, it provides insights into the plant's adaptive capacity, survival and growth. The ability to rapidly quantify this parameter for C. arabica under different agroecological systems would be an indispensable tool. Using a Flir E6 MIR Camera, an index that is equivalent to stomatal conductance (I g ) was compared with stomatal conductance measurements (g s ) in a mature coffee plantation. In order to account for varying meteorological conditions between days, the methods were also compared under stable meteorological conditions in a laboratory and I g was also converted to absolute stomatal conductance values (g 1 ). In contrast to typical plant-thermography methods which measure indices once per day over an extended time period, we used high resolution hourly measurements over daily time series with 9 sun and 9 shade replicates. Eight daily time series showed a strong correlation between methods, while the remaining 10 were not significant. Including several other meteorological parameters in the calculation of g 1 did not contribute to any stronger correlation between methods. Total pooled data (combined daily series) resulted in a correlation of ρ=0.66 (P≤2.2e-16), indicating that our approach is particularly useful for situations where absolute values of stomatal conductance are not required, such as for comparative purposes, screening or trend analysis. We use the findings to advance the protocol for a more accurate methodology which may assist in quantifying advantageous microenvironment designs for coffee, considering the current and future climates of coffee growing regions. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  10. The effect of denture stability, occlusion, oral hygiene and smoking on denture-induced stomatitis

    International Nuclear Information System (INIS)

    Nimri, Gadeer Mukatash

    2008-01-01

    This longitudinal clinical investigation was undertaken to find out the effect of denture wearing habit (day versus day and night), denture hygiene and cigarette smoking habit on the frequency of denture induced stomatitis. Comparisons were made between 240 complete denture wearers, half of whom were asked to wear their dentures at the daytime only and the other half to wear the denture day and night. All these participants were male patients with a mean age of 57.6 years who had received maxillary complete acrylic dentures for the first time. Fifty percent of the samples were smokers. A standard method for examination of the mouth and denture construction, insertion and follow up were employed. Putative risk factors (denture wearing habits, denture hygiene and smoking) were investigated. Subjects were recalled 12 months after insertion to examine the quality of the denture and the condition of the maxillary mucosa. No significant correlation was found between deterioration of stability or occlusion and type of habitual use of the dentures (P > 0.05). Fourteen percent of the cases reported with inflamed maxillary mucosa. Deterioration of retention or occlusion separately showed no correlation with the condition of the mucosa. However, associated deterioration of both stability and occlusion proved to be significantly correlated with the occurrence of denture stomatitis (P < 0.05). Denture stomatitis was significantly more frequently with subjects wearing their dentures overnight compared with those who removed them (P < 0.05). A significant correlation was also found between cigarette smoking, poor oral hygiene and the presence of denture induced stomatitis (P < 0.05). Nocturnal denture wearing habit, deficient oral and denture hygiene, and cigarette smoking are all important predisposing factors to denture-induced stomatitis, however, none of these factors was the sole cause of mucosal inflammation. (author)

  11. Seasonal stomatal behavior of a common desert shrub and the influence of plant neighbors.

    Science.gov (United States)

    Kropp, Heather; Ogle, Kiona

    2015-02-01

    Stomata simultaneously regulate plant carbon gain and water loss, and patterns of stomatal conductance (g(s)) provide insight into water use strategies. In arid systems, g(s) varies seasonally based on factors such as water availability and temperature. Moreover, the presence and species identity of neighboring plants likely affects g(s) of the focal plant by altering available soil water and microclimate conditions. We investigated stomatal behavior in Larrea tridentata, a drought-tolerant, evergreen shrub occurring throughout the arid southwestern United States. We measured g(s) in Larrea over multiple seasons in the presence of neighbors representing different woody species. The data were analyzed in the context of a commonly used phenomenological model that relates g(s) to vapor pressure deficit (D) to understand spatial and temporal differences in stomatal behavior. We found that g(s) in Larrea was affected by neighborhood association, and these effects varied seasonally. The greatest effect of neighborhood association on g(s) occurred during the winter period, where Larrea growing alone (without neighbors) had higher g(s) compared to Larrea growing with neighbors. Larrea's stomatal sensitivity to D and reference conductance (i.e., g(s) at D = 1 kPa) also differed significantly among different neighbor associations. Random effects indicated reference g(s) varied over short time scales (daily), while stomatal sensitivity showed little daily or seasonal variation, but was notably affected by neighbor associations such that neighboring species, especially trees, reduced Larrea's sensitivity to D. Overall, seasonal dynamics and neighborhood conditions appear critical to understanding temporal and spatial variation in Larrea's physiological behavior.

  12. Microclimate effects of crop residues on biological processes

    Science.gov (United States)

    Hatfield, J. L.; Prueger, J. H.

    1996-03-01

    plant to maintain transpiration rates at optimal levels during the early vegetative growth period. The biological implications of crop residue on the soil surface can be more positive than negative and increasing our understanding of the physical environment and biological system interactions will lead to improved resource management.

  13. Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles

    Science.gov (United States)

    Hanquist, Kyle M.; Hara, Kentaro; Boyd, Iain D.

    2017-02-01

    Electron transpiration cooling (ETC) is a recently proposed approach to manage the high heating loads experienced at the sharp leading edges of hypersonic vehicles. Computational fluid dynamics (CFD) can be used to investigate the feasibility of ETC in a hypersonic environment. A modeling approach is presented for ETC, which includes developing the boundary conditions for electron emission from the surface, accounting for the space-charge limit effects of the near-wall plasma sheath. The space-charge limit models are assessed using 1D direct-kinetic plasma sheath simulations, taking into account the thermionically emitted electrons from the surface. The simulations agree well with the space-charge limit theory proposed by Takamura et al. for emitted electrons with a finite temperature, especially at low values of wall bias, which validates the use of the theoretical model for the hypersonic CFD code. The CFD code with the analytical sheath models is then used for a test case typical of a leading edge radius in a hypersonic flight environment. The CFD results show that ETC can lower the surface temperature of sharp leading edges of hypersonic vehicles, especially at higher velocities, due to the increase in ionized species enabling higher electron heat extraction from the surface. The CFD results also show that space-charge limit effects can limit the ETC reduction of surface temperatures, in comparison to thermionic emission assuming no effects of the electric field within the sheath.

  14. [Photosynthetic rate, transpiration rate, and water use efficiency of cotton canopy in oasis edge of Linze].

    Science.gov (United States)

    Xie, Ting-Ting; Su, Pei-Xi; Gao, Song

    2010-06-01

    The measurement system of Li-8100 carbon flux and the modified assimilation chamber were used to study the photosynthetic characteristics of cotton (Gossypium hirsutum L.) canopy in the oasis edge region in middle reach of Heihe River Basin, mid Hexi Corridor of Gansu. At the experimental site, soil respiration and evaporation rates were significantly higher in late June than in early August, and the diurnal variation of canopy photosynthetic rate showed single-peak type. The photosynthetic rate was significantly higher (P water use efficiency in late June and early August was (15.67 +/- 1.77) mmol CO2 x mol(-1) H2O and (23.08 +/- 5.54) mmol CO2 x mol(-1) H2O, respectively, but the difference was not significant (P > 0.05). Both in late June and in early August, the canopy photosynthetic rate was positively correlated with air temperature, PAR, and soil moisture content, suggesting that there was no midday depression of photosynthesis in the two periods. In August, the canopy photosynthetic rate and transpiration rate decreased significantly, because of the lower soil moisture content and leaf senescence, but the canopy water use efficiency had no significant decrease.

  15. Evaluation of a low cost wireless heat ratio method system for measuring transpiration

    Science.gov (United States)

    Eiriksson, D.; Boyer, B.; Aishlin, P. S.; Bowling, D. R.

    2016-12-01

    For decades, environmental measurements in remote locations have consisted of sensors hard wired to loggers that send data to central servers via radio, satellite, or cellular telemetry. This model of data collection is effective when all sensors are located in close proximity to the central data logger, such as on a weather station. Frequently, however, in order to adequately capture the spatial heterogeneity associated with environmental processes (e.g., transpiration, soil moisture, or snow depth), it is necessary to install many sensors 10's to 100's of meters from a central data logging station. This presents a practical and financial obstacle when considering the cost of cabling and conduit, in addition to the potential data collection and data quality problems associated with long cable runs. We offer a solution to this persistent challenge with a hybrid datalogging system that combines the power and reliability of Campbell Scientific logging and telemetry equipment with low cost Xbee radios and Arduino based data logging platforms. To evaluate the promise of this hybrid datalogging concept we developed a new generation of low cost, homemade heat ratio sapflux sensors and tested them at a forested site in the Wasatch Mountains, near Salt Lake City, Utah. We present data from this test site, heat ratio method sensor construction details, and example code that merges the capabilities of Arduino and Campbell Scientific datalogging systems.

  16. Inhibition by acrolein of light-induced stomatal opening through inhibition of inward-rectifying potassium channels in Arabidopsis thaliana.

    Science.gov (United States)

    Islam, Md Moshiul; Ye, Wenxiu; Matsushima, Daiki; Khokon, Md Atiqur Rahman; Munemasa, Shintaro; Nakamura, Yoshimasa; Murata, Yoshiyuki

    2015-01-01

    Acrolein is a reactive α,β-unsaturated aldehyde derived from lipid peroxides, which are produced in plants under a variety of stress. We investigated effects of acrolein on light-induced stomatal opening using Arabidopsis thaliana. Acrolein inhibited light-induced stomatal opening in a dose-dependent manner. Acrolein at 100 μM inhibited plasma membrane inward-rectifying potassium (Kin) channels in guard cells. Acrolein at 100 μM inhibited Kin channel KAT1 expressed in a heterologous system using Xenopus leaves oocytes. These results suggest that acrolein inhibits light-induced stomatal opening through inhibition of Kin channels in guard cells.

  17. Partitioning of evaporation into transpiration, soil evaporation and interception: a comparison between isotope measurements and a HYDRUS-1D model

    Directory of Open Access Journals (Sweden)

    S. J. Sutanto

    2012-08-01

    Full Text Available Knowledge of the water fluxes within the soil-vegetation-atmosphere system is crucial to improve water use efficiency in irrigated land. Many studies have tried to quantify these fluxes, but they encountered difficulties in quantifying the relative contribution of evaporation and transpiration. In this study, we compared three different methods to estimate evaporation fluxes during simulated summer conditions in a grass-covered lysimeter in the laboratory. Only two of these methods can be used to partition total evaporation into transpiration, soil evaporation and interception. A water balance calculation (whereby rainfall, soil moisture and percolation were measured was used for comparison as a benchmark. A HYDRUS-1D model and isotope measurements were used for the partitioning of total evaporation. The isotope mass balance method partitions total evaporation of 3.4 mm d−1 into 0.4 mm d−1 for soil evaporation, 0.3 mm d−1 for interception and 2.6 mm d−1 for transpiration, while the HYDRUS-1D partitions total evaporation of 3.7 mm d−1 into 1 mm d−1 for soil evaporation, 0.3 mm d−1 for interception and 2.3 mm d−1 for transpiration. From the comparison, we concluded that the isotope mass balance is better for low temporal resolution analysis than the HYDRUS-1D. On the other hand, HYDRUS-1D is better for high temporal resolution analysis than the isotope mass balance.

  18. Changing Stomatal Conductance in Response to Anthropogenic Climate Change: a Model-Data Comparison

    Science.gov (United States)

    Purcell, C.; Batke, S.; Caballero, R.; McElwain, J.

    2015-12-01

    Understanding the response of stomatal conductance to increasing anthropogenic CO2 is of critical importance for the evaluation of the global hydrological cycle, and has implications for future climate change, particularly flood and risk. Via physiological and morphological changes in leaf structure, stomatal conductance has been shown to decrease under elevated CO2 conditions, stimulating higher vegetation water use efficiency and water retention within the land system. However, an assessment of how the simulation of changing stomatal conductance in an Earth System Model compares with observational data under varying CO2 concentrations (Free Air CO2 Enrichment - FACE - studies) has not yet been conducted, and is crucial for considering the significance of the issue of flooding for global policy making. Here we utilise the Community Land Model, Version 4.5 (CLM4.5), performing climate simulations over a range of atmospheric CO2 concentrations from 350ppm to 700ppm (50ppm increments), and compare the model data with results from a conclusive set of FACE studies (350ppm - 700ppm range). We show general agreement between the climate model and FACE data with regards to decreasing stomatal conductance in response to increasing CO2 concentration. However the magnitudes of the conductance changes differ, spatially within the model, and across species in the FACE studies. We show how the model can be used to assess global stomatal conductance changes on spatial scales where FACE cannot (ie. most FACE studies are located across the 30°- 60° latitude belt). This is useful for understanding the role of groundwater retention and potential flood risk at regional scales across the globe. Additionally the model demonstrates seasonal-spatial changes in stomatal conductance in response to CO2 forcing. Such seasonal changes are generally absent throughout FACE studies, as measurement is predominantly tasked during summer months. Our results reiterate the importance of climate

  19. Effects of carbonyl sulfide (COS) and carbonic anhydrase on stomatal conductance

    Science.gov (United States)

    Yakir, D.; Stimler, K.; Berry, J. A.

    2011-12-01

    The potential use of COS as tracer of the gross, one-way, CO2 flux into plants is based on its co-diffusion with CO2 into leaves without outflux stimulated research on COS-CO2 interactions during leaf gas exchange. We carried out gas exchange measurements of COS and CO2 in 22 plant species representing deciduous and evergreen trees, grasses, and shrubs, under a range of light intensities and ambient COS concentrations, using mid IR laser spectroscopy. A narrow range in the normalized ratio of the net uptake rates of COS (As) and CO2 (Ac; As/Ac*[CO2]/[COS]) was observed, with a mean value of 1.61±0.26. These results reflect the dominance of stomatal conductance over both COS and CO2 uptake, imposing a relatively constant ratio between the two fluxes (except under low light conditions when CO2, but not COS, metabolism is light limited). A relatively constant ratio under common ambient conditions will facilitate the application of COS as a tracer of gross photosynthesis from leaf to global scales. However, its effect on stomatal conductance may require a special attention. Increasing COS concentrations between 250 and 2800 pmol mol-1 (enveloping atmospheric levels) seems to stimulate stomatal conductance. We examined the stimulation of conductance by COS in a range of species and show that there is a large variation with some species showing almost no response while others are highly responsive (up to doubling stomatal conductance). Using C3 and C4 plants with antisense lines abolishing carbonic anhydrase activity, we show that the activity of this enzyme is essential for both the uptake of COS and the enhancement of stomatal conductance by COS. Since carbonic anhydrase catalyzes the conversion of COS to CO2 and H2S it seems likely that the stomata are responding to H2S produced in the mesophyll. In all natural species examined the uptake of COS and CO2 were highly correlated, and there was no relationship between the sensitivity of stomata and the rate of COS uptake

  20. Photosynthesis and Transpiration Rates of Rice Cultivated Under the System of Rice Intensification and the Effects on Growth and Yield

    Directory of Open Access Journals (Sweden)

    Nurul Hidayati

    2016-04-01

    Full Text Available The system of rice intensification (SRI crop management method has been reported by many authors to significantly increase rice yield with lower inputs, but physiological bases of yielding improvement has not been studied. In this research we assessed some physiological parameters and the mechanism of rice yield improvement of rice plants under SRI cultivation method during both vegetative and generative phases compared to conventional rice cultivation methods. We measured photosynthetic rate, transpiration rate, leaf temperature, chlorophyll content, N and P uptake, plant growth parameters and yield for those comparison. SRI methods significantly increased both vegetative and reproductive (generative parameters of rice plants compared to conventional cultivation methods. Photosynthetic rate, chlorophyll content, N and P uptake under SRI cultivation were significantly higher compared to those of the conventional rice cultivation, but no differences were found in transpiration rate and leaf temperature. With SRI method, plants in their generative phase (especially in the grain-filling phase had the highest photosynthetic and the lowest transpiration rates. Grain yield under SRI method was significantly higher (ca. 24% than that of conventional method.

  1. Validation of a simple evaporation-transpiration scheme (SETS) to estimate evaporation using micro-lysimeter measurements

    Science.gov (United States)

    Ghazanfari, Sadegh; Pande, Saket; Savenije, Hubert

    2014-05-01

    Several methods exist to estimate E and T. The Penman-Montieth or Priestly-Taylor methods along with the Jarvis scheme for estimating vegetation resistance are commonly used to estimate these fluxes as a function of land cover, atmospheric forcing and soil moisture content. In this study, a simple evaporation transpiration method is developed based on MOSAIC Land Surface Model that explicitly accounts for soil moisture. Soil evaporation and transpiration estimated by SETS is validated on a single column of soil profile with measured evaporation data from three micro-lysimeters located at Ferdowsi University of Mashhad synoptic station, Iran, for the year 2005. SETS is run using both implicit and explicit computational schemes. Results show that the implicit scheme estimates the vapor flux close to that by the explicit scheme. The mean difference between the implicit and explicit scheme is -0.03 mm/day. The paired T-test of mean difference (p-Value = 0.042 and t-Value = 2.04) shows that there is no significant difference between the two methods. The sum of soil evaporation and transpiration from SETS is also compared with P-M equation and micro-lysimeters measurements. The SETS predicts the actual evaporation with a lower bias (= 1.24mm/day) than P-M (= 1.82 mm/day) and with R2 value of 0.82.

  2. Uptake of 32P and 86Rb as influenced by temperature, transpiration suppress and shading treatment in rice plants

    International Nuclear Information System (INIS)

    Lee, G.B.; Hong, Y.P.; Im, J.N.; Chung, K.W.

    1989-01-01

    This study was carried out to know the uptake pattern of phosphorous and potassium in rice plants using by two radioisotopes, 32P and 86Rb as tracers for two years, 1987 and 1988. Rice plants were grown in the hydroponic culture with Yoshida's solution, and treated with different temperatures, transpiration suppress, shading, and phosphorous and potassium deletions. The uptake amount of 32P and 86Rb were increased with the increasing temperature in root sphere of rice plant, particularly remarkable increase of 86Rb uptake at 35deg C. The uptake of 32P tended to be promoted at the treatment of low air-high water temperature (17-30deg C), while that of 86Rb was not significantly differenced from different temperature treatments. The effect of transpiration on the uptake of 32P and 86Rb was extremely low. This phenomenon may suggest that the absorption be depending on active uptake rather than passive one by transpiration stream. The total carbohydrate contents of rice root were decreased by shading treatment, resulting significant reduction in the uptake of 32P and 86Rb. The uptake of 86Rb was remarkably increased in the treatment of potassium deletion, but that of 32P was not significantly increased in the delection of phosphorous

  3. Sapfluxnet: a global database of sap flow measurements to unravel the ecological factors of transpiration regulation in woody plants

    Science.gov (United States)

    Poyatos, Rafael; Martínez-Vilalta, Jordi; Molowny-Horas, Roberto; Steppe, Kathy; Oren, Ram; Katul, Gabriel; Mahecha, Miguel

    2016-04-01

    Plant transpiration is one of the main components of the global water cycle, it controls land energy balance, determines catchment hydrological responses and exerts strong feedbacks on regional and global climate. At the same time, plant productivity, growth and survival are severely constrained by water availability, which is expected to decline in many areas of the world because of global-change driven increases in drought conditions. While global surveys of drought tolerance traits at the organ level are rapidly increasing our knowledge of the diversity in plant functional strategies to cope with drought stress, a whole-plant perspective of drought vulnerability is still lacking. Sap flow measurements using thermal methods have now been applied to measure seasonal patterns in water use and the response of transpiration to environmental drivers across hundreds of species of woody plants worldwide, covering a wide range of climates, soils and stand structural characteristics. Here, we present the first effort to build a global database of sub-daily, tree-level sap flow (SAPFLUXNET) that will be used to improve our understanding of physiological and structural determinants of plant transpiration and to further investigate the role of vegetation in controlling global water balance. We already have the expression of interest of data contributors representing >115 globally distributed sites, > 185 species and > 700 trees, measured over at least one growing season. However, the potential number of available sites and species is probably much higher given that > 2500 sap flow-related papers have been identified in a Scopus literature search conducted in November 2015. We will give an overview of how data collection, harmonisation and quality control procedures are implemented within the project. We will also discuss potential analytical strategies to synthesize hydroclimatic controls on sap flow into biologically meaningful traits related to whole-plant transpiration

  4. Water stable isotope shifts of surface waters as proxies to quantify evaporation, transpiration and carbon uptake on catchment scales

    Science.gov (United States)

    Barth, Johannes; van Geldern, Robert; Veizer, Jan; Karim, Ajaz; Freitag, Heiko; Fowlwer, Hayley

    2017-04-01

    Comparison of water stable isotopes of rivers to those of precipitation enables separation of evaporation from transpiration on the catchment scale. The method exploits isotope ratio changes that are caused exclusively by evaporation over longer time periods of at least one hydrological year. When interception is quantified by mapping plant types in catchments, the amount of water lost by transpiration can be determined. When in turn pairing transpiration with the water use efficiency (WUE i.e. water loss by transpiration per uptake of CO2) and subtracting heterotrophic soil respiration fluxes (Rh), catchment-wide carbon balances can be established. This method was applied to several regions including the Great Lakes and the Clyde River Catchments ...(Barth, et al., 2007, Karim, et al., 2008). In these studies evaporation loss was 24 % and 1.3 % and transpiration loss was 47 % and 22 % when compared to incoming precipitation for the Great Lakes and the Clyde Catchment, respectively. Applying WUE values for typical plant covers and using area-typical Rh values led to estimates of CO2 uptake of 251 g C m-2 a-1 for the Great Lakes Catchment and CO2 loss of 21 g C m2 a-1 for the Clyde Catchment. These discrepancies are most likely due to different vegetation covers. The method applies to scales of several thousand km2 and has good potential for improvement via calibration on smaller scales. This can for instance be achieved by separate treatment of sub-catchments with more detailed mapping of interception as a major unknown. These previous studies have shown that better uncertainty analyses are necessary in order to estimate errors in water and carbon balances. The stable isotope method is also a good basis for comparison to other landscape carbon balances for instance by eddy covariance techniques. This independent method and its up-scaling combined with the stable isotope and area-integrating methods can provide cross validation of large-scale carbon budgets

  5. Habitat Temperature and Precipitation of Arabidopsis thaliana Ecotypes Determine the Response of Foliar Vasculature, Photosynthesis, and Transpiration to Growth Temperature.

    Science.gov (United States)

    Adams, William W; Stewart, Jared J; Cohu, Christopher M; Muller, Onno; Demmig-Adams, Barbara

    2016-01-01

    Acclimatory adjustments of foliar vascular architecture, photosynthetic capacity, and transpiration rate in Arabidopsis thaliana ecotypes (Italian, Polish [Col-0], Swedish) were characterized in the context of habitat of origin. Temperatures of the habitat of origin decreased linearly with increasing habitat latitude, but habitat precipitation was greatest in Italy, lowest in Poland, and intermediate in Sweden. Plants of the three ecotypes raised under three different growth temperature regimes (low, moderate, and high) exhibited highest photosynthetic capacities, greatest leaf thickness, highest chlorophyll a/b ratio and levels of β-carotene, and greatest levels of wall ingrowths in phloem transfer cells, and, in the Col-0 and Swedish ecotypes, of phloem per minor vein in plants grown at the low temperature. In contrast, vein density and minor vein tracheary to sieve element ratio increased with increasing growth temperature - most strongly in Col-0 and least strongly in the Italian ecotype - and transpirational water loss correlated with vein density and number of tracheary elements per minor vein. Plotting of these vascular features as functions of climatic conditions in the habitat of origin suggested that temperatures during the evolutionary history of the ecotypes determined acclimatory responses of the foliar phloem and photosynthesis to temperature in this winter annual that upregulates photosynthesis in response to lower temperature, whereas the precipitation experienced during the evolutionary history of the ecotypes determined adjustment of foliar vein density, xylem, and transpiration to temperature. In particular, whereas photosynthetic capacity, leaf thickness, and foliar minor vein phloem features increased linearly with increasing latitude and decreasing temperature of the habitats of origin in response to experimental growth at low temperature, transpiration rate, foliar vein density, and minor vein tracheary element numbers and cross

  6. Ferns are less dependent on passive dilution by cell expansion to coordinate leaf vein and stomatal spacing than angiosperms.

    Directory of Open Access Journals (Sweden)

    Madeline R Carins Murphy

    Full Text Available Producing leaves with closely spaced veins is a key innovation linked to high rates of photosynthesis in angiosperms. A close geometric link between veins and stomata in angiosperms ensures that investment in enhanced venous water transport provides the strongest net carbon return to the plant. This link is underpinned by "passive dilution" via expansion of surrounding cells. However, it is not known whether this 'passive dilution' mechanism is present in plant lineages other than angiosperms and is another key feature of the angiosperms' evolutionary success. Consequently, we sought to determine whether the 'passive dilution' mechanism is; (i exclusive to the angiosperms, (ii a conserved mechanism that evolved in the common ancestor of ferns and angiosperms, or (iii has evolved continuously over time. To do this we first we assessed the plasticity of vein and stomatal density and epidermal cell size in ferns in response to light environment. We then compared the relationships between these traits found among ferns with modelled relationships that assume vein and stomatal density respond passively to epidermal cell expansion, and with those previously observed in angiosperms. Vein density, stomatal density and epidermal cell size were linked in ferns with remarkably similar relationships to those observed in angiosperms, except that fern leaves had fewer veins per stomata. However, plasticity was limited in ferns and stomatal spacing was dependent on active stomatal differentiation as well as passive cell expansion. Thus, ferns (like angiosperms appear to coordinate vein and stomatal density with epidermal cell expansion to some extent to maintain a constant ratio between veins and stomata in the leaf. The different general relationships between vein density and stomatal density in ferns and angiosperms suggests the groups have different optimum balances between the production of vein tissue dedicated to water supply and stomatal tissue for gas

  7. Antifungal Effect of Henna against Candida albicans Adhered to Acrylic Resin as a Possible Method for Prevention of Denture Stomatitis

    OpenAIRE

    Nawasrah, Amal; AlNimr, Amani; Ali, Aiman A.

    2016-01-01

    Denture stomatitis is a very common disease affecting the oral mucosa of denture wearers. The aim of this study was to measure the antifungal effect of henna against Candida albicans adhered to acrylic resin as a possible method for prevention of denture stomatitis. One-hundred-eighty acrylic plates were prepared of heat-cured acrylic denture resin. The specimens were divided into six groups of 30 samples each. The first group was only polymer and monomer following the conventional manufactur...

  8. Drought limitations to leaf-level gas exchange: results from a model linking stomatal optimization and cohesion-tension theory

    Science.gov (United States)

    Kimberly A. Novick; Chelcy F. Miniat; James M. Vose

    2016-01-01

    We merge concepts from stomatal optimization theory and cohesion–tension theory to examine the dynamics of three mechanisms that are potentially limiting to leaf-level gas exchange in trees during drought: (1) a ‘demand limitation’ driven by an assumption of optimal stomatal functioning; (2) ‘hydraulic limitation’ of water movement from the roots to the leaves...

  9. Increased contribution of wheat nocturnal transpiration to daily water use under drought.

    Science.gov (United States)

    Claverie, Elodie; Meunier, Félicien; Javaux, Mathieu; Sadok, Walid

    2018-03-01

    Increasing evidence suggests that in crops, nocturnal water use could represent 30% of daytime water consumption, particularly in semi-arid and arid areas. This raises the questions of whether nocturnal transpiration rates (TR N ) are (1) less influenced by drought than daytime TR (TR D ), (2) increased by higher nocturnal vapor pressure deficit (VPD N ), which prevails in such environments and (3) involved in crop drought tolerance. In this investigation, we addressed those questions by subjecting two wheat genotypes differing in drought tolerance to progressive soil drying under two long-term VPD N regimes imposed under naturally fluctuating conditions. A first goal was to characterize the response curves of whole-plant TR N and TR N /TR D ratios to progressive soil drying. A second goal was to examine the effect of VPD N increase on TR N response to soil drying and on 13 other developmental traits. The study revealed that under drought, TR N was not responsive to progressive soil drying and - intriguingly - that TR N seemingly increased with drought under high VPD N consistently for the drought-sensitive genotype. Because TR D was concomitantly decreasing with progressive drought, this resulted in TR N representing up to 70% of TR D at the end of the drydown. In addition, under drought, VPD N increase was found not to influence traits such as leaf area or stomata density. Overall, those findings indicate that TR N contribution to daily water use under drought might be much higher than previously thought, that it is controlled by specific mechanisms and that decreasing TR N under drought might be a valuable trait for improving drought tolerance. © 2017 Scandinavian Plant Physiology Society.

  10. Ecophysiological variation of transpiration of pine forests: synthesis of new and published results.

    Science.gov (United States)

    Tor-Ngern, Pantana; Oren, Ram; Oishi, Andrew C; Uebelherr, Joshua M; Palmroth, Sari; Tarvainen, Lasse; Ottosson-Löfvenius, Mikaell; Linder, Sune; Domec, Jean-Christophe; Näsholm, Torgny

    2017-01-01

    Canopy transpiration (E C ) is a large fraction of evapotranspiration, integrating physical and biological processes within the energy, water, and carbon cycles of forests. Quantifying E C is of both scientific and practical importance, providing information relevant to questions ranging from energy partitioning to ecosystem services, such as primary productivity and water yield. We estimated E C of four pine stands differing in age and growing on sandy soils. The stands consisted of two wide-ranging conifer species: Pinus taeda and Pinus sylvestris, in temperate and boreal zones, respectively. Combining results from these and published studies on all soil types, we derived an approach to estimate daily E C of pine forests, representing a wide range of conditions from 35° S to 64° N latitude. During the growing season and under moist soils, maximum daily E C (E Cm ) at day-length normalized vapor pressure deficit of 1 kPa (E Cm-ref ) increased by 0.55 ± 0.02 (mean ± SE) mm/d for each unit increase of leaf area index (L) up to L = ~5, showing no sign of saturation within this range of quickly rising mutual shading. The initial rise of E Cm with atmospheric demand was linearly related to E Cm-ref . Both relations were unaffected by soil type. Consistent with theoretical prediction, daily E C was sensitive to decreasing soil moisture at an earlier point of relative extractable water in loamy than sandy soils. Our finding facilitates the estimation of daily E C of wide-ranging pine forests using remotely sensed L and meteorological data. We advocate an assembly of worldwide sap flux database for further evaluation of this approach. © 2016 by the Ecological Society of America.

  11. Functional convergence of oxylipin and abscisic acid pathways controls stomatal closure in response to drought.

    Science.gov (United States)

    Savchenko, Tatyana; Kolla, Venkat A; Wang, Chang-Quan; Nasafi, Zainab; Hicks, Derrick R; Phadungchob, Bpantamars; Chehab, Wassim E; Brandizzi, Federica; Froehlich, John; Dehesh, Katayoon

    2014-03-01

    Membranes are primary sites of perception of environmental stimuli. Polyunsaturated fatty acids are major structural constituents of membranes that also function as modulators of a multitude of signal transduction pathways evoked by environmental stimuli. Different stresses induce production of a distinct blend of oxygenated polyunsaturated fatty acids, "oxylipins." We employed three Arabidopsis (Arabidopsis thaliana) ecotypes to examine the oxylipin signature in response to specific stresses and determined that wounding and drought differentially alter oxylipin profiles, particularly the allene oxide synthase branch of the oxylipin pathway, responsible for production of jasmonic acid (JA) and its precursor 12-oxo-phytodienoic acid (12-OPDA). Specifically, wounding induced both 12-OPDA and JA levels, whereas drought induced only the precursor 12-OPDA. Levels of the classical stress phytohormone abscisic acid (ABA) were also mainly enhanced by drought and little by wounding. To explore the role of 12-OPDA in plant drought responses, we generated a range of transgenic lines and exploited the existing mutant plants that differ in their levels of stress-inducible 12-OPDA but display similar ABA levels. The plants producing higher 12-OPDA levels exhibited enhanced drought tolerance and reduced stomatal aperture. Furthermore, exogenously applied ABA and 12-OPDA, individually or combined, promote stomatal closure of ABA and allene oxide synthase biosynthetic mutants, albeit most effectively when combined. Using tomato (Solanum lycopersicum) and Brassica napus verified the potency of this combination in inducing stomatal closure in plants other than Arabidopsis. These data have identified drought as a stress signal that uncouples the conversion of 12-OPDA to JA and have revealed 12-OPDA as a drought-responsive regulator of stomatal closure functioning most effectively together with ABA.

  12. Are stomatal responses the key to understanding the cost of fungal disease resistance in plants?

    Science.gov (United States)

    Withers, Catherine M; Gay, Alan P; Mur, Luis A J

    2011-07-01

    Preventing disease in cereal crops is important for maintaining productivity and as the availability and efficacy of chemical control becomes reduced the emphasis on breeding for disease resistance increases. However, there is evidence that disease resistance may be physiologically costly to the plant and we ask if understanding stomatal responses to fungal attack is the key to minimising reductions in growth associated with disease resistance. Copyright © 2011 Society of Chemical Industry.

  13. The influence of climate change on stomatal ozone flux to a mountain Norway spruce forest

    Czech Academy of Sciences Publication Activity Database

    Zapletal, M.; Pretel, J.; Chroust, P.; Cudlín, Pavel; Edwards-Jonášová, Magda; Urban, Otmar; Pokorný, Radek; Czerný, Radek; Hůnová, I.

    2012-01-01

    Roč. 169, OCT 2012 (2012), s. 267-273 ISSN 0269-7491 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA MŠk OC10022; GA MŠk(CZ) LM2010007 Institutional research plan: CEZ:AV0Z60870520 Keywords : Stomatal ozone flux * AOT40 * Phytotoxic Ozone Dose * Norway spruce * Net ecosystem production * Ozone * Climate change Subject RIV: EH - Ecology, Behaviour Impact factor: 3.730, year: 2012

  14. Modelling of stomatal conductance and ozone deposition flux of Norway Spruce using deposition model

    Czech Academy of Sciences Publication Activity Database

    Zapletal, M.; Chroust, P.; Večeřa, Zbyněk; Mikuška, Pavel; Cudlín, Pavel; Urban, Otmar; Pokorný, Radek; Czerný, Radek; Janouš, Dalibor; Taufarová, Klára

    2009-01-01

    Roč. 12, 2-3 (2009), s. 75-81 ISSN 1335-339X R&D Projects: GA MŽP SP/1B7/189/07 Institutional research plan: CEZ:AV0Z60870520; CEZ:AV0Z40310501 Keywords : ozone concentration * ozone deposition * stomatal conductance * deposition velocity * resistance model * tropo-spheric ozone Subject RIV: DG - Athmosphere Sciences, Meteorology

  15. Longevity of guard cell chloroplasts in falling leaves: implication for stomatal function and cellular aging

    Energy Technology Data Exchange (ETDEWEB)

    Zeiger, E.; Schwartz, A.

    1982-11-12

    Guard cell chloroplasts in senescing leaves from 12 species of perennial trees and three species of annual plants survived considerably longer than their mesophyll counterparts. In Ginkgo biloba, stomata from yellow leaves opened during the day and closed at night; guard cell chloroplasts from these leaves showed fluorescence transients associated with electron transport and photophosphorylation. These findings indicate that guard cell chloroplasts are highly conserved throughout the life-span of the leaf and that leaves retain stomatal control during senescence.

  16. Quantitative Evaluation of Stomatal Cytoskeletal Patterns during the Activation of Immune Signaling in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Masaki Shimono

    Full Text Available Historically viewed as primarily functioning in the regulation of gas and water vapor exchange, it is now evident that stomata serve an important role in plant immunity. Indeed, in addition to classically defined functions related to cell architecture and movement, the actin cytoskeleton has emerged as a central component of the plant immune system, underpinning not only processes related to cell shape and movement, but also receptor activation and signaling. Using high resolution quantitative imaging techniques, the temporal and spatial changes in the actin microfilament array during diurnal cycling of stomatal guard cells has revealed a highly orchestrated transition from random arrays to ordered bundled filaments. While recent studies have demonstrated that plant stomata close in response to pathogen infection, an evaluation of stimulus-induced changes in actin cytoskeletal dynamics during immune activation in the guard cell, as well as the relationship of these changes to the function of the actin cytoskeleton and stomatal aperture, remains undefined. In the current study, we employed quantitative cell imaging and hierarchical clustering analyses to define the response of the guard cell actin cytoskeleton to pathogen infection and the elicitation of immune signaling. Using this approach, we demonstrate that stomatal-localized actin filaments respond rapidly, and specifically, to both bacterial phytopathogens and purified pathogen elicitors. Notably, we demonstrate that higher order temporal and spatial changes in the filament array show distinct patterns of organization during immune activation, and that changes in the naïve diurnal oscillations of guard cell actin filaments are perturbed by pathogens, and that these changes parallel pathogen-induced stomatal gating. The data presented herein demonstrate the application of a highly tractable and quantifiable method to assign transitions in actin filament organization to the activation of

  17. Quantitative Evaluation of Stomatal Cytoskeletal Patterns during the Activation of Immune Signaling in Arabidopsis thaliana

    Science.gov (United States)

    Shimono, Masaki; Higaki, Takumi; Kaku, Hanae; Shibuya, Naoto; Hasezawa, Seiichiro

    2016-01-01

    Historically viewed as primarily functioning in the regulation of gas and water vapor exchange, it is now evident that stomata serve an important role in plant immunity. Indeed, in addition to classically defined functions related to cell architecture and movement, the actin cytoskeleton has emerged as a central component of the plant immune system, underpinning not only processes related to cell shape and movement, but also receptor activation and signaling. Using high resolution quantitative imaging techniques, the temporal and spatial changes in the actin microfilament array during diurnal cycling of stomatal guard cells has revealed a highly orchestrated transition from random arrays to ordered bundled filaments. While recent studies have demonstrated that plant stomata close in response to pathogen infection, an evaluation of stimulus-induced changes in actin cytoskeletal dynamics during immune activation in the guard cell, as well as the relationship of these changes to the function of the actin cytoskeleton and stomatal aperture, remains undefined. In the current study, we employed quantitative cell imaging and hierarchical clustering analyses to define the response of the guard cell actin cytoskeleton to pathogen infection and the elicitation of immune signaling. Using this approach, we demonstrate that stomatal-localized actin filaments respond rapidly, and specifically, to both bacterial phytopathogens and purified pathogen elicitors. Notably, we demonstrate that higher order temporal and spatial changes in the filament array show distinct patterns of organization during immune activation, and that changes in the naïve diurnal oscillations of guard cell actin filaments are perturbed by pathogens, and that these changes parallel pathogen-induced stomatal gating. The data presented herein demonstrate the application of a highly tractable and quantifiable method to assign transitions in actin filament organization to the activation of immune signaling in

  18. Stomatal Frequency and Atmospheric CO2: a Model Based on Photosynthesis and Gaseous Diffusion

    Science.gov (United States)

    Roth-Nebelsick, A.; Konrad, W.

    2004-12-01

    Gaseous exchange in land plants occurs via micropores on the plant surface, the stomata. The stomatal frequency (SF) of leaves has attracted considerable interest with respect to increasing atmospheric CO2 since Woodward (1987) demonstrated that this parameter changes inversely with CO2 in various species. The response is due to 1) individual phenotypic plasticity and 2) evolutionary change, depending on the considered time scale. The SF-CO2 response is regarded to represent a valuable device for determining past atmospheric CO2 concentration and SF data from fossil plant material are therefore often used as CO2 proxies. There are, however, numerous difficulties which have to be considered, such as: 1) high variance of the data, especially for fossil material, 2) interspecific differences of the response, 3) the CO2 ceiling (= weak or no response under CO2 concentration higher than ambient) and 4) differences between short-term and long-term responses. Although processes related to plant gaseous exchange are assumed to represent the causal basis for the response, no clear explanatory model has yet been proposed and even doubts have emerged about the real existence of this phenomenon. In this contribution it is shown that results obtained with a model based on diffusion and assimilation suggest that the SF-CO2 response is a structural adjustment of maximum stomatal conductance. The results 1) offer a clear explanation for the often observed weak response of stomatal frequency to CO2 levels higher than ambient, 2) provide a simple equation for calculating ancient CO2 levels from stomatal data, and 3) can contribute to predictions concerning plant reactions to elevated CO2 levels in the future.

  19. Évaluation des caractéristiques des stomates chez le palmier à huile ...

    African Journals Online (AJOL)

    SARAH

    31 août 2016 ... indicateurs de la pollution locale de l'air (Koffi et al.,. 2014). L'objectif principal de ce travail est de déterminer les paramètres caractéristiques des stomates chez le palmier à huile normal diploïde afin d'appliquer dans le futur les méthodes de la. Biotechnologie. Les objectifs spécifiques portent sur.

  20. Applicability of common stomatal conductance models in maize under varying soil moisture conditions.

    Science.gov (United States)

    Wang, Qiuling; He, Qijin; Zhou, Guangsheng

    2018-07-01

    In the context of climate warming, the varying soil moisture caused by precipitation pattern change will affect the applicability of stomatal conductance models, thereby affecting the simulation accuracy of carbon-nitrogen-water cycles in ecosystems. We studied the applicability of four common stomatal conductance models including Jarvis, Ball-Woodrow-Berry (BWB), Ball-Berry-Leuning (BBL) and unified stomatal optimization (USO) models based on summer maize leaf gas exchange data from a soil moisture consecutive decrease manipulation experiment. The results showed that the USO model performed best, followed by the BBL model, BWB model, and the Jarvis model performed worst under varying soil moisture conditions. The effects of soil moisture made a difference in the relative performance among the models. By introducing a water response function, the performance of the Jarvis, BWB, and USO models improved, which decreased the normalized root mean square error (NRMSE) by 15.7%, 16.6% and 3.9%, respectively; however, the performance of the BBL model was negative, which increased the NRMSE by 5.3%. It was observed that the models of Jarvis, BWB, BBL and USO were applicable within different ranges of soil relative water content (i.e., 55%-65%, 56%-67%, 37%-79% and 37%-95%, respectively) based on the 95% confidence limits. Moreover, introducing a water response function, the applicability of the Jarvis and BWB models improved. The USO model performed best with or without introducing the water response function and was applicable under varying soil moisture conditions. Our results provide a basis for selecting appropriate stomatal conductance models under drought conditions. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Radioimmunological determination of plasma cortisol following application of a stomatic paste containing prednisolone (DontisolonR)

    International Nuclear Information System (INIS)

    Stehn, H.

    1985-01-01

    A radioimmunological method was used to determine the cortisol plasma levels of 69 patients, treated with a stomatic paste containing prednisolone. Significant changes in plasma cortisol were only established in connection with a dose regimen of 3 times 1.25 mg daily. In isolated cases, however, there were major decreases in response to exposure to prednisolone. Therefore, the anamnestic data of any one patient being prescribed corticoids must be examined with care. (TRV) [de

  2. Modelling stomatal ozone flux and deposition to grassland communities across Europe

    Energy Technology Data Exchange (ETDEWEB)

    Ashmore, M.R. [Environment Department, University of York, Heslington, York YO10 5DD (United Kingdom)]. E-mail: ma512@york.ac.uk; Bueker, P. [Stockholm Environment Institute at York, University of York, York YO10 5DD (United Kingdom); Emberson, L.D. [Stockholm Environment Institute at York, University of York, York YO10 5DD (United Kingdom); Terry, A.C. [Environment Department, University of York, Heslington, York YO10 5DD (United Kingdom); Toet, S. [Environment Department, University of York, Heslington, York YO10 5DD (United Kingdom)

    2007-04-15

    Regional scale modelling of both ozone deposition and the risk of ozone impacts is poorly developed for grassland communities. This paper presents new predictions of stomatal ozone flux to grasslands at five different locations in Europe, using a mechanistic model of canopy development for productive grasslands to generate time series of leaf area index and soil water potential as inputs to the stomatal component of the DO{sub 3}SE ozone deposition model. The parameterisation of both models was based on Lolium perenne, a dominant species of productive pasture in Europe. The modelled seasonal time course of stomatal ozone flux to both the whole canopy and to upper leaves showed large differences between climatic zones, which depended on the timing of the start of the growing season, the effect of soil water potential, and the frequency of hay cuts. Values of modelled accumulated flux indices and the AOT40 index showed a five-fold difference between locations, but the locations with the highest flux differed depending on the index used; the period contributing to the accumulation of AOT40 did not always coincide with the modelled period of active ozone canopy uptake. Use of a fixed seasonal profile of leaf area index in the flux model produced very different estimates of annual accumulated total canopy and leaf ozone flux when compared with the flux model linked to a simulation of canopy growth. Regional scale model estimates of both the risks of ozone impacts and of total ozone deposition will be inaccurate unless the effects of climate and management in modifying grass canopy growth are incorporated. - Modelled stomatal flux of ozone to productive grasslands in Europe shows different spatial and temporal variation to AOT40, and is modified by management and soil water status.

  3. Stomatal sensitivity to vapour pressure deficit relates to climate of origin in Eucalyptus species.

    Science.gov (United States)

    Bourne, Aimee E; Haigh, Anthony M; Ellsworth, David S

    2015-03-01

    Selecting plantation species to balance water use and production requires accurate models for predicting how species will tolerate and respond to environmental conditions. Although interspecific variation in water use occurs, species-specific parameters are rarely incorporated into physiologically based models because often the appropriate species parameters are lacking. To determine the physiological control over water use in Eucalyptus, five stands of Eucalyptus species growing in a common garden were measured for sap flux rates and their stomatal response to vapour pressure deficit (D) was assessed. Maximal canopy conductance and whole-canopy stomatal sensitivity to D and reduced water availability were lower in species originating from more arid climates of origin than those from humid climates. Species from humid climates showed a larger decline in maximal sap flux density (JSmax) with reduced water availability, and a lower D at which stomatal closure occurred than species from more arid climates, implying larger sensitivity to water availability and D in these species. We observed significant (P species climate of origin with mean vessel diameter (R(2) = 0.90), stomatal sensitivity to D (R(2) = 0.83) and the size of the decline in JSmax to restricted water availability (R(2) = 0.94). Thus aridity of climate of origin appears to have a selective role in constraining water-use response among the five Eucalyptus plantation species. These relationships emphasize that within this congeneric group of species, climate aridity constrains water use. These relationships have implications for species choices for tree plantation success against drought-induced losses and the ability to manage Eucalyptus plantations against projected changes in water availability and evaporation in the future. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  4. Protective efficacy of a recombinant Newcastle disease virus expressing glycoprotein of vesicular stomatitis virus in mice

    OpenAIRE

    Zhang, Minmin; Ge, Jinying; Li, Xiaofang; Chen, Weiye; Wang, Xijun; Wen, Zhiyuan; Bu, Zhigao

    2016-01-01

    Background Vesicular stomatitis virus (VSV) causes severe losses to the animal husbandry industry. In this study, a recombinant Newcastle disease virus (NDV) expressing the glycoprotein (G) of VSV (rL-VSV-G) was constructed and its pathogenicity and immune protective efficacy in mouse were evaluated. Results In pathogenicity evaluation test, the analysis of the viral distribution in mouse organs and body weight change showed that rL-VSV-G was safe in mice. In immune protection assay, the reco...

  5. Tubulin perturbation leads to unexpected cell wall modifications and affects stomatal behaviour in Populus.

    Science.gov (United States)

    Swamy, Prashant S; Hu, Hao; Pattathil, Sivakumar; Maloney, Victoria J; Xiao, Hui; Xue, Liang-Jiao; Chung, Jeng-Der; Johnson, Virgil E; Zhu, Yingying; Peter, Gary F; Hahn, Michael G; Mansfield, Shawn D; Harding, Scott A; Tsai, Chung-Jui

    2015-10-01

    Cortical microtubules are integral to plant morphogenesis, cell wall synthesis, and stomatal behaviour, presumably by governing cellulose microfibril orientation. Genetic manipulation of tubulins often leads to abnormal plant development, making it difficult to probe additional roles of cortical microtubules in cell wall biogenesis. Here, it is shown that expressing post-translational C-terminal modification mimics of α-tubulin altered cell wall characteristics and guard cell dynamics in transgenic Populus tremula x alba that otherwise appear normal. 35S promoter-driven transgene expression was high in leaves but unusually low in xylem, suggesting high levels of tubulin transgene expression were not tolerated in wood-forming tissues during regeneration of transformants. Cellulose, hemicellulose, and lignin contents were unaffected in transgenic wood, but expression of cell wall-modifying enzymes, and extractability of lignin-bound pectin and xylan polysaccharides were increased in developing xylem. The results suggest that pectin and xylan polysaccharides deposited early during cell wall biogenesis are more sensitive to subtle tubulin perturbation than cellulose and matrix polysaccharides deposited later. Tubulin perturbation also affected guard cell behaviour, delaying drought-induced stomatal closure as well as light-induced stomatal opening in leaves. Pectins have been shown to confer cell wall flexibility critical for reversible stomatal movement, and results presented here are consistent with microtubule involvement in this process. Taken together, the data show the value of growth-compatible tubulin perturbations for discerning microtubule functions, and add to the growing body of evidence for microtubule involvement in non-cellulosic polysaccharide assembly during cell wall biogenesis. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  6. Elevation-related variation in leaf stomatal traits as a function of plant functional type: evidence from Changbai Mountain, China.

    Directory of Open Access Journals (Sweden)

    Ruili Wang

    Full Text Available Understanding the variation in stomatal characteristics in relation to climatic gradients can reveal the adaptation strategies of plants, and help us to predict their responses to future climate changes. In this study, we investigated stomatal density (SD and stomatal length (SL in 150 plant species along an elevation gradient (540-2357 m in Changbai Mountain, China, and explored the patterns and drivers of stomatal characteristics across species and plant functional types (PFTs: trees, shrubs, and herbs. The average values of SD and SL for all species combined were 156 mm(-2 and 35 µm, respectively. SD was higher in trees (224 mm(-2 than in shrubs (156 mm(-2 or herbs (124 mm(-2, and SL was largest in herbs (37 µm. SD was negatively correlated with SL in all species and PFTs (P < 0.01. The relationship between stomatal characteristics and elevation differed among PFTs. In trees, SD decreased and SL increased with elevation; in shrubs and herbs, SD initially increased and then decreased. Elevation-related differences in SL were not significant. PFT explained 7.20-17.6% of the total variation in SD and SL; the contributions of CO2 partial pressure (P CO2, precipitation, and soil water content (SWC were weak (0.02-2.28%. Our findings suggest that elevation-related patterns of stomatal characteristics in leaves are primarily a function of PFT, and highlight the importance of differences among PFTs in modeling gas exchange in terrestrial ecosystems under global climate change.

  7. Sensitivity of infrared water vapor analyzers to oxygen concentration and errors in stomatal conductance.

    Science.gov (United States)

    Bunce, James A

    2002-01-01

    Use of infrared analyzers to measure water vapor concentrations in photosynthesis systems is becoming common. It is known that sensitivity of infrared carbon dioxide and water vapor analyzers is affected by the oxygen concentration in the background gas, particularly for absolute analyzers, but the potential for large errors in estimates of stomatal conductance due to effects of oxygen concentration on the sensitivity of infrared water vapor analyzers is not widely recognized. This work tested three types of infrared water vapor analyzers for changes in sensitivity of infrared water vapor analyzers depending on the oxygen content of the background gas. It was found that changing from either 0 or 2% to 21% oxygen in nitrogen decreased the sensitivity to water vapor for all three types of infrared water vapor analyzers by about 4%. The change in sensitivity was linear with oxygen mole fraction. The resulting error in calculated stomatal conductance would depend strongly on the leaf to air vapor pressure difference and leaf temperature, and also on whether leaf temperature was directly measured or calculated from energy balance. Examples of measurements of gas exchange on soybean leaves under glasshouse conditions indicated that changing from 21% to 2% oxygen produced an artifactual apparent increase in stomatal conductance which averaged about 30%. Similar errors occurred for 'conductances' of wet filter paper. Such errors could affect inferences about the carbon dioxide dependence of the sensitivity of photosynthesis to oxygen.

  8. Maximum leaf conductance driven by CO2 effects on stomatal size and density over geologic time.

    Science.gov (United States)

    Franks, Peter J; Beerling, David J

    2009-06-23

    Stomatal pores are microscopic structures on the epidermis of leaves formed by 2 specialized guard cells that control the exchange of water vapor and CO(2) between plants and the atmosphere. Stomatal size (S) and density (D) determine maximum leaf diffusive (stomatal) conductance of CO(2) (g(c(max))) to sites of assimilation. Although large variations in D observed in the fossil record have been correlated with atmospheric CO(2), the crucial significance of similarly large variations in S has been overlooked. Here, we use physical diffusion theory to explain why large changes in S necessarily accompanied the changes in D and atmospheric CO(2) over the last 400 million years. In particular, we show that high densities of small stomata are the only way to attain the highest g(cmax) values required to counter CO(2)"starvation" at low atmospheric CO(2) concentrations. This explains cycles of increasing D and decreasing S evident in the fossil history of stomata under the CO(2) impoverished atmospheres of the Permo-Carboniferous and Cenozoic glaciations. The pattern was reversed under rising atmospheric CO(2) regimes. Selection for small S was crucial for attaining high g(cmax) under falling atmospheric CO(2) and, therefore, may represent a mechanism linking CO(2) and the increasing gas-exchange capacity of land plants over geologic time.

  9. Stomatal conductance of lettuce grown under or exposed to different light qualities

    Science.gov (United States)

    Kim, Hyeon-Hye; Goins, Gregory D.; Wheeler, Raymond M.; Sager, John C.

    2004-01-01

    BACKGROUND AND AIMS: The objective of this research was to examine the effects of differences in light spectrum on the stomatal conductance (Gs) and dry matter production of lettuce plants grown under a day/night cycle with different spectra, and also the effects on Gs of short-term exposure to different spectra. METHODS: Lettuce (Lactuca sativa) plants were grown with 6 h dark and 18 h light under four different spectra, red-blue (RB), red-blue-green (RBG), green (GF) and white (CWF), and Gs and plant growth were measured. KEY RESULTS AND CONCLUSIONS: Conductance of plants grown for 23 d under CWF rose rapidly on illumination to a maximum in the middle of the light period, then decreased again before the dark period when it was minimal. However, the maximum was smaller in plants grown under RB, RGB and GF. This demonstrates that spectral quality during growth affects the diurnal pattern of stomatal conductance. Although Gs was smaller in plants grown under RGB than CWF, dry mass accumulation was greater, suggesting that Gs did not limit carbon assimilation under these spectral conditions. Temporarily changing the spectral quality of the plants grown for 23 d under CWF, affected stomatal responses reversibly, confirming studies on epidermal strips. This study provides new information showing that Gs is responsive to spectral quality during growth and, in the short-term, is not directly coupled to dry matter accumulation.

  10. Stomatal responses in isolated epidermis of the crassulacean acid metabolism plant Kalanchoe daigremontiana Hamet et Perr.

    Science.gov (United States)

    Jewer, P C; Incoll, L D; Howarth, G L

    1981-11-01

    The optimal conditions for opening of stomata in detached epidermis of the Crassulacean Acid Metabolism (CAM) plant Kalanchoe daigremontiana were determined. Stomatal opening in CO2-free air was unaffected by light so subsequently all epidermal strips were incubated in the dark and in CO2-free air. Apertures were maximal after 3 h incubation and were significantly greater at 15° C than 25° C. Thus stomata in isolated epidermis of this species can respond directly to temperature. Stomatal opening was greatest when the incubating buffer contained 17.6 mol m(-3) K(+), but decreased linearly with increasing K(+) concentrations between 17.6 and 300 mol m(-3); the decrease in aperture was shown to be associated with increasing osmotic potentials of the solutions. Reasons for this behaviour, which differs from that of many C3 and C4 species, are discussed. Stomatal apertures declined linearly upon incubation of epidermis on buffer solutions containing between 10(-11) and 10(-5) mol m(-3) abscisic acid (ABA). Hence stomata on isolated epidermis of K. daigremontiana respond to lower concentrations of ABA than those of any species reported previously.

  11. Maximum leaf conductance driven by CO2 effects on stomatal size and density over geologic time

    Science.gov (United States)

    Franks, Peter J.; Beerling, David J.

    2009-01-01

    Stomatal pores are microscopic structures on the epidermis of leaves formed by 2 specialized guard cells that control the exchange of water vapor and CO2 between plants and the atmosphere. Stomatal size (S) and density (D) determine maximum leaf diffusive (stomatal) conductance of CO2 (gcmax) to sites of assimilation. Although large variations in D observed in the fossil record have been correlated with atmospheric CO2, the crucial significance of similarly large variations in S has been overlooked. Here, we use physical diffusion theory to explain why large changes in S necessarily accompanied the changes in D and atmospheric CO2 over the last 400 million years. In particular, we show that high densities of small stomata are the only way to attain the highest gcmax values required to counter CO2“starvation” at low atmospheric CO2 concentrations. This explains cycles of increasing D and decreasing S evident in the fossil history of stomata under the CO2 impoverished atmospheres of the Permo-Carboniferous and Cenozoic glaciations. The pattern was reversed under rising atmospheric CO2 regimes. Selection for small S was crucial for attaining high gcmax under falling atmospheric CO2 and, therefore, may represent a mechanism linking CO2 and the increasing gas-exchange capacity of land plants over geologic time. PMID:19506250

  12. Recalibrating the Ginkgo Stomatal Index Proxy for Past CO2 with Herbarium Specimens

    Science.gov (United States)

    Conde, G. D.; Retallack, G.

    2015-12-01

    The stomatal index of plant cuticles is inversely related to atmospheric CO2 concentrations, as calibrated from greenhouse experiments and herbarium specimens. Such calibration data for Ginkgo biloba are available for the ongoing rise in atmospheric CO2 and for high levels of CO2 anticipated in the future, but lacking for low CO2 levels of preindustrial and glacial ages. The oldest modern specimen that we have been able to obtain consists of leaf fragments collected in 1829 and provided by Arne Anderberg from the Swedish Natural History Museum. The specimen was labeled "Argentina", but also "Hortus Botanicus Augustinus", a garden founded in 1638 in Amsterdam, Netherlands. Ginkgo has a very thin cuticle that is difficult to prepare, but images very similar to cuticular preparation can be obtained by backscatter SEM imagery. We also obtained secondary SEM images of the same areas and counted 13 images with 6,184 cells from five leaf fragments. Our analyses yield a stomatal index of 10.9 ± 0.9 % for an atmospheric CO2 of 286 ppm, as determined by ice core data from Ciais and Sabine for IPCC-2013. This value is lower than from previous calibration curves for this level of CO2 and changes their curvature. With additional late nineteenth, twentieth and twenty-first century leaves, we can improve both the precision and lower limits of the transfer function for atmospheric CO2 from Ginkgo stomatal index last revised in 2009.

  13. An ancestral stomatal patterning module revealed in the non-vascular land plant Physcomitrella patens.

    Science.gov (United States)

    Caine, Robert S; Chater, Caspar C; Kamisugi, Yasuko; Cuming, Andrew C; Beerling, David J; Gray, Julie E; Fleming, Andrew J

    2016-09-15

    The patterning of stomata plays a vital role in plant development and has emerged as a paradigm for the role of peptide signals in the spatial control of cellular differentiation. Research in Arabidopsis has identified a series of epidermal patterning factors (EPFs), which interact with an array of membrane-localised receptors and associated proteins (encoded by ERECTA and TMM genes) to control stomatal density and distribution. However, although it is well-established that stomata arose very early in the evolution of land plants, until now it has been unclear whether the established angiosperm stomatal patterning system represented by the EPF/TMM/ERECTA module reflects a conserved, universal mechanism in the plant kingdom. Here, we use molecular genetics to show that the moss Physcomitrella patens has conserved homologues of angiosperm EPF, TMM and at least one ERECTA gene that function together to permit the correct patterning of stomata and that, moreover, elements of the module retain function when transferred to Arabidopsis Our data characterise the stomatal patterning system in an evolutionarily distinct branch of plants and support the hypothesis that the EPF/TMM/ERECTA module represents an ancient patterning system. © 2016. Published by The Company of Biologists Ltd.

  14. Non-stomatal limitation to photosynthesis in Cinnamomum camphora seedings exposed to elevated O3.

    Science.gov (United States)

    Niu, Junfeng; Feng, Zhaozhong; Zhang, Weiwei; Zhao, Ping; Wang, Xiaoke

    2014-01-01

    Ozone (O3) is the most phytotoxic air pollutant for global forests, with decreased photosynthesis widely regarded as one of its most common effects. However, controversy exists concerning the mechanism that underlies the depressing effects of O3 on CO2 assimilation. In the present study, seedlings of Cinnamomum camphora, a subtropical evergreen tree species that has rarely been studied, were exposed to ambient air (AA), ambient air plus 60 [ppb] O3 (AA+60), or ambient air plus 120 [ppb] O3 (AA+120) in open-top chambers (OTCs) for 2 years. Photosynthetic CO2 exchange and chlorophyll a fluorescence were investigated in the second growing season (2010). We aim to determine whether stomatal or non-stomatal limitation is responsible for the photosynthesis reduction and to explore the potential implications for forest ecosystem functions. Results indicate that elevated O3 (E-O3) reduced the net photosynthetic rates (PN) by 6.0-32.2%, with significant differences between AA+60 and AA+120 and across the four measurement campaigns (MCs). The actual photochemical efficiency of photosystem II (PSII) in saturated light (Fv'/Fm') was also significantly decreased by E-O3, as was the effective quantum yield of PSII photochemistry (ΦPSII). Moreover, E-O3 significantly and negatively impacted the maximum rates of carboxylation (Vcmax) and electron transport (Jmax). Although neither the stomatal conductance (gs) nor the intercellular CO2 concentration (Ci) was decreased by E-O3, PN/gs was significantly reduced. Therefore, the observed reduction in PN in the present study should not be attributed to the unavailability of CO2 due to stomatal limitation, but rather to the O3-induced damage to Ribulose-1,5-bisphosphate carboxylase/oxygenase and the photochemical apparatus. This suggests that the down-regulation of stomatal conductance could fail to occur, and the biochemical processes in protoplasts would become more susceptible to injuries under long-term O3 exposure, which may have

  15. CO2-induced decrease of canopy stomatal conductance of mature conifer and broadleaved trees

    Science.gov (United States)

    Tor-ngern, P.; Oren, R.; Ward, E. J.; Palmroth, S.; McCarthy, H. R.; domec, J.

    2013-12-01

    Together with canopy leaf area, mean canopy stomatal conductance (GS) controls forest-atmosphere exchanges of energy and mass. Expectations for stomatal response to elevated atmospheric [CO2] (CO2E) based on seedling studies range from large decreases of conductance in foliage of broadleaved species to little or no response in conifers. These responses are not directly translatable to forest canopies, and their underlying mechanisms are ill-defined. The uncertainty of canopy-scale stomatal response to CO2E reduces confidence in modeled predictions of future forest productivity and carbon sequestration, and of partitioning of net radiation between latent and sensible heat flux. Thus, debates on the potential effects of CO2E-induced stomatal closure continue. We used a Free-Air CO2 Enrichment (FACE) experiment in a 27-year-old, 25 m tall forest, to generate a whole-canopy CO2-response and test whether canopy-scale GS response to CO2E of widely distributed, fast growing shade-intolerant species, Pinus taeda (L.) and co-occurring broadleaved species dominated by Liquidambar styraciflua (L.), was indirectly affected by slow changes such as hydraulic adjustments and canopy development, as opposed to quickly responding to CO2 concentrations in the leaf-internal air space. Our results show indirect CO2E-induced reductions of GS of 10% and 30%, respectively, and no signs of a direct stomatal response even as CO2E was pushed to 685 μmol mol-1 (~1.8 of ambient). Modeling the effect of CO2E on the water, energy and carbon cycles of forests must consider slow-response indirect mechanisms producing large variation in the reduction of GS, such as the previously observed inconsistent CO2E effect on canopy leaf area and plant hydraulics. Moreover, the new generation of CO2E studies in forests must allow indirect effects caused by, e.g., hydraulic adjustments and canopy development, to play out. Such acclimation will be particularly prolonged in slowly developing ecosystems, such

  16. Residual gas analysis

    International Nuclear Information System (INIS)

    Berecz, I.

    1982-01-01

    Determination of the residual gas composition in vacuum systems by a special mass spectrometric method was presented. The quadrupole mass spectrometer (QMS) and its application in thin film technology was discussed. Results, partial pressure versus time curves as well as the line spectra of the residual gases in case of the vaporization of a Ti-Pd-Au alloy were demonstrated together with the possible construction schemes of QMS residual gas analysers. (Sz.J.)

  17. Benefits of increasing transpiration efficiency in wheat under elevated CO2for rainfed regions.

    Science.gov (United States)

    Christy, Brendan; Tausz-Posch, Sabine; Tausz, Michael; Richards, Richard; Rebetzke, Greg; Condon, Anthony; McLean, Terry; Fitzgerald, Glenn; Bourgault, Maryse; O'Leary, Garry

    2018-01-13

    Higher transpiration efficiency (TE) has been proposed as a mechanism to increase crop yields in dry environments where water availability usually limits yield. The application of a coupled radiation and TE simulation model shows wheat yield advantage of a high-TE cultivar (cv. Drysdale) over its almost identical low-TE parent line (Hartog), from about -7 to 558 kg/ha (mean 187 kg/ha) over the rainfed cropping region in Australia (221-1,351 mm annual rainfall), under the present-day climate. The smallest absolute yield response occurred in the more extreme drier and wetter areas of the wheat belt. However, under elevated CO 2 conditions, the response of Drysdale was much greater overall, ranging from 51 to 886 kg/ha (mean 284 kg/ha) with the greatest response in the higher rainfall areas. Changes in simulated TE under elevated CO 2 conditions are seen across Australia with notable increased areas of higher TE under a drier climate in Western Australia, Queensland and parts of New South Wales and Victoria. This improved efficiency is subtly deceptive, with highest yields not necessarily directly correlated with highest TE. Nevertheless, the advantage of Drysdale over Hartog is clear with the benefit of the trait advantage attributed to TE ranging from 102% to 118% (mean 109%). The potential annual cost-benefits of this increased genetic TE trait across the wheat growing areas of Australia (5 year average of area planted to wheat) totaled AUD 631 MIL (5-year average wheat price of AUD/260 t) with an average of 187 kg/ha under the present climate. The benefit to an individual farmer will depend on location but elevated CO 2 raises this nation-wide benefit to AUD 796 MIL in a 2°C warmer climate, slightly lower (AUD 715 MIL) if rainfall is also reduced by 20%. © 2018 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

  18. Differentiating transpiration from evaporation in seasonal agricultural wetlands and the link to advective fluxes in the root zone

    Science.gov (United States)

    Bachand, P.A.M.; S. Bachand,; Fleck, Jacob A.; Anderson, Frank E.; Windham-Myers, Lisamarie

    2014-01-01

    The current state of science and engineering related to analyzing wetlands overlooks the importance of transpiration and risks data misinterpretation. In response, we developed hydrologic and mass budgets for agricultural wetlands using electrical conductivity (EC) as a natural conservative tracer. We developed simple differential equations that quantify evaporation and transpiration rates using flowrates and tracer concentrations atwetland inflows and outflows. We used two ideal reactormodel solutions, a continuous flowstirred tank reactor (CFSTR) and a plug flow reactor (PFR), to bracket real non-ideal systems. From those models, estimated transpiration ranged from 55% (CFSTR) to 74% (PFR) of total evapotranspiration (ET) rates, consistent with published values using standard methods and direct measurements. The PFR model more appropriately represents these nonideal agricultural wetlands in which check ponds are in series. Using a fluxmodel, we also developed an equation delineating the root zone depth at which diffusive dominated fluxes transition to advective dominated fluxes. This relationship is similar to the Peclet number that identifies the dominance of advective or diffusive fluxes in surface and groundwater transport. Using diffusion coefficients for inorganic mercury (Hg) and methylmercury (MeHg) we calculated that during high ET periods typical of summer, advective fluxes dominate root zone transport except in the top millimeters below the sediment–water interface. The transition depth has diel and seasonal trends, tracking those of ET. Neglecting this pathway has profound implications: misallocating loads along different hydrologic pathways; misinterpreting seasonal and diel water quality trends; confounding Fick's First Law calculations when determining diffusion fluxes using pore water concentration data; and misinterpreting biogeochemicalmechanisms affecting dissolved constituent cycling in the root zone. In addition,our understanding of internal

  19. Carbon dioxide and the stomatal control of water balance and photosynthesis in higher plants. Progress report, July 1, 1990--June 30, 1992

    Energy Technology Data Exchange (ETDEWEB)

    1992-07-01

    Research continued into the investigation of the effects of carbon dioxide on stomatal control of water balance and photosynthesis in higher plants. Topics discussed this period include a method of isolating a sufficient number of guard cell chloroplasts for biochemical studies by mechanical isolation of epidermal peels; the measurement of stomatal apertures with a digital image analysis system; development of a high performance liquid chromatography method for quantification of metabolites in guard cells; and genetic control of stomatal movements in Pima cotton. (CBS)

  20. Overexpression of plasma membrane H+-ATPase in guard cells promotes light-induced stomatal opening and enhances plant growth.

    Science.gov (United States)

    Wang, Yin; Noguchi, Ko; Ono, Natsuko; Inoue, Shin-ichiro; Terashima, Ichiro; Kinoshita, Toshinori

    2014-01-07

    Stomatal pores surrounded by a pair of guard cells in the plant epidermis control gas exchange between plants and the atmosphere in response to light, CO2, and the plant hormone abscisic acid. Light-induced stomatal opening is mediated by at least three key components: the blue light receptor phototropin (phot1 and phot2), plasma membrane H(+)-ATPase, and plasma membrane inward-rectifying K(+) channels. Very few attempts have been made to enhance stomatal opening with the goal of increasing photosynthesis and plant growth, even though stomatal resistance is thought to be the major limiting factor for CO2 uptake by plants. Here, we show that transgenic Arabidopsis plants overexpressing H(+)-ATPase using the strong guard cell promoter GC1 showed enhanced light-induced stomatal opening, photosynthesis, and plant growth. The transgenic plants produced larger and increased numbers of rosette leaves, with ∼42-63% greater fresh and dry weights than the wild type in the first 25 d of growth. The dry weights of total flowering stems of 45-d-old transgenic plants, including seeds, siliques, and flowers, were ∼36-41% greater than those of the wild type. In addition, stomata in the transgenic plants closed normally in response to darkness and abscisic acid. In contrast, the overexpression of phototropin or inward-rectifying K(+) channels in guard cells had no effect on these phenotypes. These results demonstrate that stomatal aperture is a limiting factor in photosynthesis and plant growth, and that manipulation of stomatal opening by overexpressing H(+)-ATPase in guard cells is useful for the promotion of plant growth.

  1. The role of callose in guard-cell wall differentiation and stomatal pore formation in the fern Asplenium nidus.

    Science.gov (United States)

    Apostolakos, P; Livanos, P; Nikolakopoulou, T L; Galatis, B

    2009-12-01

    The pattern of callose deposition was followed in developing stomata of the fern Asplenium nidus to investigate the role of this polysaccharide in guard cell (GC) wall differentiation and stomatal pore formation. Callose was localized by aniline blue staining and immunolabelling using an antibody against (1 --> 3)-beta-d-glucan. The study was carried out in stomata of untreated material as well as of material treated with: (1) 2-deoxy-d-glucose (2-DDG) or tunicamycin, which inhibit callose synthesis; (2) coumarin or 2,6-dichlorobenzonitrile (dichlobenil), which block cellulose synthesis; (3) cyclopiazonic acid (CPA), which disturbs cytoplasmic Ca(2+) homeostasis; and (d) cytochalasin B or oryzalin, which disintegrate actin filaments and microtubules, respectively. In post-cytokinetic stomata significant amounts of callose persisted in the nascent ventral wall. Callose then began degrading from the mid-region of the ventral wall towards its periphery, a process which kept pace with the formation of an 'internal stomatal pore' by local separation of the partner plasmalemmata. In differentiating GCs, callose was consistently localized in the developing cell-wall thickenings. In 2-DDG-, tunicamycin- and CPA-affected stomata, callose deposition and internal stomatal pore formation were inhibited. The affected ventral walls and GC wall thickenings contained membranous elements. Stomata recovering from the above treatments formed a stomatal pore by a mechanism different from that in untreated stomata. After coumarin or dichlobenil treatment, callose was retained in the nascent ventral wall for longer than in control stomata, while internal stomatal pore formation was blocked. Actin filament disintegration inhibited internal stomatal pore formation, without any effect on callose deposition. In A. nidus stomata the time and pattern of callose deposition and degradation play an essential role in internal stomatal pore formation, and callose participates in deposition of the

  2. The Plasma Membrane H+-ATPase AHA1 Plays a Major Role in Stomatal Opening in Response to Blue Light.

    Science.gov (United States)

    Yamauchi, Shota; Takemiya, Atsushi; Sakamoto, Tomoaki; Kurata, Tetsuya; Tsutsumi, Toshifumi; Kinoshita, Toshinori; Shimazaki, Ken-Ichiro

    2016-08-01

    Stomata open in response to a beam of weak blue light under strong red light illumination. A blue light signal is perceived by phototropins and transmitted to the plasma membrane H(+)-ATPase that drives stomatal opening. To identify the components in this pathway, we screened for mutants impaired in blue light-dependent stomatal opening. We analyzed one such mutant, provisionally named blus2 (blue light signaling2), and found that stomatal opening in leaves was impaired by 65%, although the magnitude of red light-induced opening was not affected. Blue light-dependent stomatal opening in the epidermis and H(+) pumping in guard cell protoplasts were inhibited by 70% in blus2 Whole-genome resequencing identified a mutation in the AHA1 gene of the mutant at Gly-602. T-DNA insertion mutants of AHA1 exhibited a similar phenotype to blus2; this phenotype was complemented by the AHA1 gene. We renamed blus2 as aha1-10 T-DNA insertion mutants of AHA2 and AHA5 did not show any impairment in stomatal response, although the transcript levels of AHA2 and AHA5 were higher than those of AHA1 in wild-type guard cells. Stomata in ost2, a constitutively active AHA1 mutant, did not respond to blue light. A decreased amount of H(+)-ATPase in aha1-10 accounted for the reduced stomatal blue light responses and the decrease was likely caused by proteolysis of misfolded AHA1. From these results, we conclude that AHA1 plays a major role in blue light-dependent stomatal opening in Arabidopsis and that the mutation made the AHA1 protein unstable in guard cells. © 2016 American Society of Plant Biologists. All Rights Reserved.

  3. Convergence and Divergence of Signaling Events in Guard Cells during Stomatal Closure by Plant Hormones or Microbial Elicitors

    Directory of Open Access Journals (Sweden)

    AGURLA SRINIVAS

    2016-08-01

    Full Text Available Dynamic regulation of stomatal aperture is essential for plants to optimize water use and CO2 uptake. Stomatal opening or closure is accompanied by the modulation of guard cell turgor. Among the events leading to stomatal closure by plant hormones or microbial elicitors, three signaling components stand out as the major converging points. These are reactive oxygen species (ROS, cytosolic free Ca2+ and ion channels. Once formed, the ROS and free Ca2+ of guard cells regulate both downstream and upstream events. A major influence of ROS is to increase the levels of NO and cytosolic free Ca2+ in guard cells. Although the rise in NO is an important event during stomatal closure, the available evidences do not support the description of NO as the point of convergence. The rise in ROS and NO would cause an increase of free Ca2+ and modulate ion channels, through a network of events, in such a way that the guard cells lose K+/Cl-/anions. The efflux of these ions decreases the turgor of guard cells and leads to stomatal closure. Thus, ROS, NO and cytosolic free Ca2+ act as points of divergence. The other guard cell components, which are modulated during stomatal closure are G-proteins, cytosolic pH, phospholipids and sphingolipids. However, the current information on the role of these components is not convincing so as to assign them as the points of convergence or divergence. The interrelationships and interactions of ROS, NO, cytosolic pH, and free Ca2+ are quite complex and need further detailed examination. Our review is an attempt to critically assess the current status of information on guard cells, while emphasizing the convergence and divergence of signaling components during stomatal closure. The existing gaps in our knowledge are identified to stimulate further research.

  4. Hyperspectral narrowband and multispectral broadband indices for remote sensing of crop evapotranspiration and its components (transpiration and soil evaporation)

    Science.gov (United States)

    Marshall, Michael T.; Thenkabail, Prasad S.; Biggs, Trent; Post, Kirk

    2016-01-01

    Evapotranspiration (ET) is an important component of micro- and macro-scale climatic processes. In agriculture, estimates of ET are frequently used to monitor droughts, schedule irrigation, and assess crop water productivity over large areas. Currently, in situ measurements of ET are difficult to scale up for regional applications, so remote sensing technology has been increasingly used to estimate crop ET. Ratio-based vegetation indices retrieved from optical remote sensing, like the Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index, and Enhanced Vegetation Index are critical components of these models, particularly for the partitioning of ET into transpiration and soil evaporation. These indices have their limitations, however, and can induce large model bias and error. In this study, micrometeorological and spectroradiometric data collected over two growing seasons in cotton, maize, and rice fields in the Central Valley of California were used to identify spectral wavelengths from 428 to 2295 nm that produced the highest correlation to and lowest error with ET, transpiration, and soil evaporation. The analysis was performed with hyperspectral narrowbands (HNBs) at 10 nm intervals and multispectral broadbands (MSBBs) commonly retrieved by Earth observation platforms. The study revealed that (1) HNB indices consistently explained more variability in ET (ΔR2 = 0.12), transpiration (ΔR2 = 0.17), and soil evaporation (ΔR2 = 0.14) than MSBB indices; (2) the relationship between transpiration using the ratio-based index most commonly used for ET modeling, NDVI, was strong (R2 = 0.51), but the hyperspectral equivalent was superior (R2 = 0.68); and (3) soil evaporation was not estimated well using ratio-based indices from the literature (highest R2 = 0.37), but could be after further evaluation, using ratio-based indices centered on 743 and 953 nm (R2 = 0.72) or 428 and 1518 nm (R2 = 0.69).

  5. Assessing HYDRUS-2D model to estimate soil water contents and olive tree transpiration fluxes under different water distribution systems

    Science.gov (United States)

    Autovino, Dario; Negm, Amro; Rallo, Giovanni; Provenzano, Giuseppe

    2016-04-01

    In Mediterranean countries characterized by limited water resources for agricultural and societal sectors, irrigation management plays a major role to improve water use efficiency at farm scale, mainly where irrigation systems are correctly designed to guarantee a suitable application efficiency and the uniform water distribution throughout the field. In the last two decades, physically-based agro-hydrological models have been developed to simulate mass and energy exchange processes in the soil-plant-atmosphere (SPA) system. Mechanistic models like HYDRUS 2D/3D (Šimunek et al., 2011) have been proposed to simulate all the components of water balance, including actual crop transpiration fluxes estimated according to a soil potential-dependent sink term. Even though the suitability of these models to simulate the temporal dynamics of soil and crop water status has been reported in the literature for different horticultural crops, a few researches have been considering arboreal crops where the higher gradients of root water uptake are the combination between the localized irrigation supply and the three dimensional root system distribution. The main objective of the paper was to assess the performance of HYDRUS-2D model to evaluate soil water contents and transpiration fluxes of an olive orchard irrigated with two different water distribution systems. Experiments were carried out in Castelvetrano (Sicily) during irrigation seasons 2011 and 2012, in a commercial farm specialized in the production of table olives (Olea europaea L., var. Nocellara del Belice), representing the typical variety of the surrounding area. During the first season, irrigation water was provided by a single lateral placed along the plant row with four emitters per plant (ordinary irrigation), whereas during the second season a grid of emitters laid on the soil was installed in order to irrigate the whole soil surface around the selected trees. The model performance was assessed based on the

  6. Fog reduces transpiration in tree species of the Canarian relict heath-laurel cloud forest (Garajonay National Park, Spain).

    Science.gov (United States)

    Ritter, Axel; Regalado, Carlos M; Aschan, Guido

    2009-04-01

    The ecophysiologic role of fog in the evergreen heath-laurel 'laurisilva' cloud forests of the Canary Islands has not been unequivocally demonstrated, although it is generally assumed that fog water is important for the survival and the distribution of this relict paleoecosystem of the North Atlantic Macaronesian archipelagos. To determine the role of fog in this ecosystem, we combined direct transpiration measurements of heath-laurel tree species, obtained with Granier's heat dissipation probes, with micrometeorological and artificial fog collection measurements carried out in a 43.7-ha watershed located in the Garajonay National Park (La Gomera, Canary Islands, Spain) over a 10-month period. Median ambient temperature spanned from 7 to 15 degrees C under foggy conditions whereas higher values, ranging from 9 to 21 degrees C, were registered during fog-free periods. Additionally, during the periods when fog water was collected, global solar radiation values were linearly related (r2=0.831) to those under fog-free conditions, such that there was a 75+/-1% reduction in median radiation in response to fog. Fog events greatly reduced median diurnal tree transpiration, with rates about 30 times lower than that during fog-free conditions and approximating the nighttime rates in both species studied (the needle-like leaf Erica arborea L. and the broadleaf Myrica faya Ait.). This large decrease in transpiration in response to fog was independent of the time of the day, tree size and species and micrometeorological status, both when expressed on a median basis and in cumulative terms for the entire 10-month measuring period. We conclude that, in contrast to the turbulent deposition of fog water droplets on the heath-laurel species, which may be regarded as a localized hydrological phenomenon that is important for high-altitude wind-exposed E. arborea trees, the cooler, wetter and shaded microenvironment provided by the cloud immersion belt represents a large-scale effect

  7. Effects of chemical inhibitors and apyrase enzyme further document a role for apyrases and extracellular ATP in the opening and closing of stomates in Arabidopsis.

    Science.gov (United States)

    Clark, Greg; Darwin, Cameron; Mehta, Viraj; Jackobs, Faith; Perry, Tyler; Hougaard, Katia; Roux, Stan

    2013-11-01

    In Arabidopsis leaves there is a bi-phasic dose-response to applied nucleotides; i.e., lower concentrations induce stomatal opening, while higher concentrations induce closure. Two mammalian purinoceptor antagonists, PPADS and RB2, block both nucleotide-induced stomatal opening and closing. These antagonists also partially block ABA-induced stomatal closure and light-induced stomatal opening. There are two closely related Arabidopsis apyrases, AtAPY1 and AtAPY2, which are both expressed in guard cells. Here we report that low levels of apyrase chemical inhibitors can induce stomatal opening in the dark, while apyrase enzyme blocks ABA-induced stomatal closure. We also demonstrate that high concentrations of ATP induce stomatal closure in the light. Application of ATPγS and chemical apyrase inhibitors at concentrations that have no effect on stomatal closure can lower the threshold for ABA-induced closure. The closure induced by ATPγS was not observed in gpa1-3 loss-of-function mutants. These results further confirm the role of extracellular ATP in regulating stomatal apertures.

  8. Agricultural pesticide residues

    International Nuclear Information System (INIS)

    Fuehr, F.

    1984-01-01

    The utilization of tracer techniques in the study of agricultural pesticide residues is reviewed under the following headings: lysimeter experiments, micro-ecosystems, translocation in soil, degradation of pesticides in soil, biological availability of soil-applied substances, bound residues in the soil, use of macro- and microautography, double and triple labelling, use of tracer labelling in animal experiments. (U.K.)

  9. The Application of Stomatal Frequency Analysis As A Proxy For Paleo-atmospheric Co2: Calibration and Proxy-validation

    Science.gov (United States)

    Kouwenberg, L. L. R.; Wagner, F.; Kürschner, W. M.; Visscher, H.

    Stomata regulate gas-exchange in leaves and their frequency on leaves has a profound influence on the intake of CO2 and the loss of water through the stomata. Experiments and analysis of leaves that have grown naturally under the historical CO2 levels of the past 200 years have demonstrated that many plant species, especially woody an- giosperms, show a reduction in stomatal frequency in relation to a rise in atmospheric CO2. This decrease in stomatal frequency restricts water loss, while the CO2 intake is not substantially reduced due to the higher CO2 concentration in the atmosphere. This species-specific response has been successfully used to reconstruct past CO2 lev- els from the stomatal frequency on fossil leaves after careful calibration to a series of known atmospheric CO2 levels. Methods to obtain such a calibration, are discussed by example of two tree taxa, the tree birch (Betula pubescens/pendula) and the west- ern hemlock (Tsuga heterophylla). The effective use of stomatal frequency analysis as a proxy of atmospheric CO2 requires validation by determination of the influence of other factors such as light availability, humidity, temperature and leaf age on stom- atal frequency. The (dis)advantages of using experiments vs material from naturally grown trees for validation and calibration will be discussed. For angiosperm species, such as Betula, the influence of other factors besides CO2 on stomatal frequency is shown to be of a lesser magnitude when the stomatal index (the number of stomata as a proportion of epidermal cells) is used instead of the stomatal density (the number of stomata per mm2 leaf area). Stomatal frequency in Tsuga heterophylla is not influ- enced by light regime or leaf age, and the observed reduction in stomatal frequency related to the CO2 rise of the last century cannot be explained by trends in precip- itation or temperature as apparent in local climate records. Thus, these two species are considered highly suitable as proxies

  10. A genetic screen reveals Arabidopsis stomatal and/or apoplastic defenses against Pseudomonas syringae pv. tomato DC3000.

    Directory of Open Access Journals (Sweden)

    Weiqing Zeng

    2011-10-01

    Full Text Available Bacterial infection of plants often begins with colonization of the plant surface, followed by entry into the plant through wounds and natural openings (such as stomata, multiplication in the intercellular space (apoplast of the infected tissues, and dissemination of bacteria to other plants. Historically, most studies assess bacterial infection based on final outcomes of disease and/or pathogen growth using whole infected tissues; few studies have genetically distinguished the contribution of different host cell types in response to an infection. The phytotoxin coronatine (COR is produced by several pathovars of Pseudomonas syringae. COR-deficient mutants of P. s. tomato (Pst DC3000 are severely compromised in virulence, especially when inoculated onto the plant surface. We report here a genetic screen to identify Arabidopsis mutants that could rescue the virulence of COR-deficient mutant bacteria. Among the susceptible to coronatine-deficient Pst DC3000 (scord mutants were two that were defective in stomatal closure response, two that were defective in apoplast defense, and four that were defective in both stomatal and apoplast defense. Isolation of these three classes of mutants suggests that stomatal and apoplastic defenses are integrated in plants, but are genetically separable, and that COR is important for Pst DC3000 to overcome both stomatal guard cell- and apoplastic mesophyll cell-based defenses. Of the six mutants defective in bacterium-triggered stomatal closure, three are defective in salicylic acid (SA-induced stomatal closure, but exhibit normal stomatal closure in response to abscisic acid (ABA, and scord7 is compromised in both SA- and ABA-induced stomatal closure. We have cloned SCORD3, which is required for salicylic acid (SA biosynthesis, and SCORD5, which encodes an ATP-binding cassette (ABC protein, AtGCN20/AtABCF3, predicted to be involved in stress-associated protein translation control. Identification of SCORD5 begins to

  11. Plester sariawan efektif dalam mempercepat penyembuhan stomatitis aftosa rekuren dan ulkus traumatikus

    Directory of Open Access Journals (Sweden)

    Rahmi Amtha

    2017-12-01

    Full Text Available Mouth ulcer plaster is effective in accelerating the healing of recurrent aphthous stomatitis and traumatic ulcers. Recurrent aphthous stomatitis (RAS is one of the most commonly occurring oral diseases. The prevalence of oral ulceration worldwide is 4%, with RAS having the largest proportion (25%. Recurrent aphthous stomatitis is oral ulceration which has a self-limiting disease, but the specific medication to reduce pain caused by lesion is still less varied nowadays. This study aimed to examine the differences in the effectiveness between topical application of hyaluronic acid (HA, mouth ulcer plaster (MUP and 0.1% triamcinolone acetonide (TA as a positive control in the healing of RAS and traumatic ulcers (TU. This was a quasi-experimental study by measuring the lesion diameter as well as visual analogue scale (VAS pre- and post-administration of three types of medication. Kruskal-walis test results show that there are differences in effectiveness (p=0.000 of the three types of medication to cure RAS and TU. There are signicant differences in the reduction of RAS and TU lesion diameter (p = 0.015 and VAS (p = 0.038 with the use of HA and MUP on the 4th day. There is no signicant difference in effectiveness (diameter and VAS of MUP and TA medication on the fourth day (p = 0.880 and p = 1.000 respectively. There is no signicant difference among HA, MUP and TA on the healing of the lesions on the seventh day (p>0.05. It can be concluded that the effectiveness of MUP is similar to that of topical medications containing corticosteroids in the healing of RAS and traumatic ulcers. ABSTRAK Stomatitis aftosa rekuren (SAR merupakan salah satu penyakit mulut yang paling umum terjadi. Prevalensi ulserasi mulut di seluruh dunia adalah 4%, dengan SAR menempati urutan terbesar yaitu 25%. Stomatitis aftosa rekuren merupakan ulserasi mulut yang memiliki self-limiting disease, namun sediaan obat yang spesifik untuk mengurangi rasa sakit yang

  12. Enamel defects and aphthous stomatitis in celiac and healthy subjects: Systematic review and meta-analysis of controlled studies.

    Science.gov (United States)

    Nieri, Michele; Tofani, Elena; Defraia, Efisio; Giuntini, Veronica; Franchi, Lorenzo

    2017-10-01

    The aim of this systematic review was to compare the presence of enamel defects and aphthous stomatitis between celiac patients and healthy controls. A systematic review of articles selected from MEDLINE, EMBASE and Google Scholar was performed by two independent operators. Additional studies hand-searched and found in the principal dental and gastroenterology journals were included. Only controlled studies on celiac patients compared to healthy subjects were included. Independent extraction of articles by 2 authors using predefined data fields, including study quality indicators. In total, the celiac patients had greater frequency of enamel defects (odds ratio=5.69, 95%CI from 3.47 to 9.33, Pceliac patients had greater frequency of aphthous stomatitis (odds ratio=3.79, 95%CI from 2.67 to 5.39, Pceliac disease was associated with both enamel defects and aphthous stomatitis. The odds ratio estimates, however, should be interpreted with caution due to the high risk of bias showed by all the studies. In adults, the association between celiac disease and enamel defects or aphthous stomatitis was unclear because very few studies were performed on this population. The presence of enamel defects and/or aphthous stomatitis in a child affected by other typical or atypical symptoms of celiac disease represents an indication for further diagnostic exams for celiac disease. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Stomatal kinetics and photosynthetic gas exchange along a continuum of isohydric to anisohydric regulation of plant water status.

    Science.gov (United States)

    Meinzer, Frederick C; Smith, Duncan D; Woodruff, David R; Marias, Danielle E; McCulloh, Katherine A; Howard, Ava R; Magedman, Alicia L

    2017-08-01

    Species' differences in the stringency of stomatal control of plant water potential represent a continuum of isohydric to anisohydric behaviours. However, little is known about how quasi-steady-state stomatal regulation of water potential may relate to dynamic behaviour of stomata and photosynthetic gas exchange in species operating at different positions along this continuum. Here, we evaluated kinetics of light-induced stomatal opening, activation of photosynthesis and features of quasi-steady-state photosynthetic gas exchange in 10 woody species selected to represent different degrees of anisohydry. Based on a previously developed proxy for the degree of anisohydry, species' leaf water potentials at turgor loss, we found consistent trends in photosynthetic gas exchange traits across a spectrum of isohydry to anisohydry. More anisohydric species had faster kinetics of stomatal opening and activation of photosynthesis, and these kinetics were closely coordinated within species. Quasi-steady-state stomatal conductance and measures of photosynthetic capacity and performance were also greater in more anisohydric species. Intrinsic water-use efficiency estimated from leaf gas exchange and stable carbon isotope ratios was lowest in the most anisohydric species. In comparisons between gas exchange traits, species rankings were highly consistent, leading to species-independent scaling relationships over the range of isohydry to anisohydry observed. © 2017 John Wiley & Sons Ltd.

  14. A previously unknown zinc finger protein, DST, regulates drought and salt tolerance in rice via stomatal aperture control.

    Science.gov (United States)

    Huang, Xin-Yuan; Chao, Dai-Yin; Gao, Ji-Ping; Zhu, Mei-Zhen; Shi, Min; Lin, Hong-Xuan

    2009-08-01

    Abiotic stresses, such as drought and salinity, lead to crop growth damage and a decrease in crop yields. Stomata control CO(2) uptake and optimize water use efficiency, thereby playing crucial roles in abiotic stress tolerance. Hydrogen peroxide (H(2)O(2)) is an important signal molecule that induces stomatal closure. However, the molecular pathway that regulates the H(2)O(2) level in guard cells remains largely unknown. Here, we clone and characterize DST (drought and salt tolerance)-a previously unknown zinc finger transcription factor that negatively regulates stomatal closure by direct modulation of genes related to H(2)O(2) homeostasis-and identify a novel pathway for the signal transduction of DST-mediated H(2)O(2)-induced stomatal closure. Loss of DST function increases stomatal closure and reduces stomatal density, consequently resulting in enhanced drought and salt tolerance in rice. These findings provide an interesting insight into the mechanism of stomata-regulated abiotic stress tolerance, and an important genetic engineering approach for improving abiotic stress tolerance in crops.

  15. Stomatal responses to CO2 during a diel Crassulacean acid metabolism cycle in Kalanchoe daigremontiana and Kalanchoe pinnata.

    Science.gov (United States)

    von Caemmerer, Susanne; Griffiths, Howard

    2009-05-01

    To investigate the diurnal variation of stomatal sensitivity to CO2, stomatal response to a 30 min pulse of low CO2 was measured four times during a 24 h time-course in two Crassulacean acid metabolism (CAM) species Kalanchoe daigremontiana and Kalanchoe pinnata, which vary in the degree of succulence, and hence, expression and commitment to CAM. In both species, stomata opened in response to a reduction in pCO2 in the dark and in the latter half of the light period, and thus in CAM species, chloroplast photosynthesis is not required for the stomatal response to low pCO2. Stomata did not respond to a decreased pCO2 in K. daigremontiana in the light when stomata were closed, even when the supply of internal CO2 was experimentally reduced. We conclude that stomatal closure during phase III is not solely mediated by high internal pCO2, and suggest that in CAM species the diurnal variability in the responsiveness of stomata to pCO2 could be explained by hypothesizing the existence of a single CO2 sensor which interacts with other signalling pathways. When not perturbed by low pCO2, CO2 assimilation rate and stomatal conductance were correlated both in the light and in the dark in both species.

  16. Heterogenous Stomatal Closure in Response to Leaf Water Deficits Is Not a Universal Phenomenon 1

    Science.gov (United States)

    Gunasekera, Dhammika; Berkowitz, Gerald A.

    1992-01-01

    The extent and occurrence of water stress-induced “patchy” CO2 uptake across the surface of leaves was evaluated in a number of plant species. Leaves, while still attached to a plant, were illuminated and exposed to air containing [14C]CO2 before autoradiographs were developed. Plant water deficits that caused leaf water potential depression to −1.1 megapascals during a 4-day period did result in heterogenous CO2 assimilation patterns in bean (Phaseolus vulgaris). However, when the same level of stress was imposed more gradually (during 17 days), no patchy stomatal closure was evident. The patchy CO2 assimilation pattern that occurs when bean plants are subjected to a rapidly imposed stress could induce artifacts in gas exchange studies such that an effect of stress on chloroplast metabolism is incorrectly deduced. This problem was characterized by examining the relationship between photosynthesis and internal [CO2] in stressed bean leaves. When extent of heterogenous CO2 uptake was estimated and accounted for, there appeared to be little difference in this relationship between control and stressed leaves. Subjecting spinach (Spinacea oleracea) plants to stress (leaf water potential depression to −1.5 megapascals) did not appear to cause patchy stomatal closure. Wheat (Triticum aestivum) plants also showed homogenous CO2 assimilation patterns when stressed to a leaf water potential of −2.6 megapascals. It was concluded that water stress-induced patchy stomatal closure can occur to an extent that could influence the analysis of gas exchange studies. However, this phenomenon was not found to be a general response. Not all stress regimens will induce patchiness; nor will all plant species demonstrate this response to water deficits. ImagesFigure 1Figure 3Figure 4 PMID:16668692

  17. Antimicrobial photodynamic therapy for infectious stomatitis in snakes: Clinical views and microbiological findings.

    Science.gov (United States)

    Grego, Kathleen Fernandes; Carvalho, Marcelo Pires Nogueira de; Cunha, Marcos Paulo Vieira; Knöbl, Terezinha; Pogliani, Fabio Celidonio; Catão-Dias, José Luiz; Sant'Anna, Sávio Stefanini; Ribeiro, Martha Simões; Sellera, Fábio Parra

    2017-12-01

    Antimicrobial photodynamic therapy (APDT) has been broadly investigated as an alternative to treat localized infections, without leading to the selection of resistant microorganisms. Infectious stomatitis is a multifactorial disease frequently reported in captive snakes characterized by infection of the oral mucosa and surrounding tissues. In this study, we investigated methylene blue (MB)-mediated APDT to treat infectious stomatitis in snakes and verified the resistance phenotype and genotype before and after APDT. Three Boid snakes presented petechiae, edema and caseous material in their oral cavities. MB (0.01%) was applied on the lesions and after 5min they were irradiated using a red laser (λ=660nm), fluence of 280J/cm 2 , 8J and 80s per point, 100mW, spot size 0.028cm 2 and fluence rate of 3.5W/cm 2 . APDT was repeated once a week during 3 months. Samples of the lesions were collected to identify bacteria and antibiotic resistance profiles. To analyze the clonality of bacterial isolates before and after APDT, isolates were subjected to ERIC PCR analysis. Snakes presented clinical improvement such as reduction of inflammatory signs and caseous material. Pseudomonas aeruginosa and Escherichia coli were present in all snakes; Klebsiella pneumoniae and Morganella morganii were also identified in some animals. We also observed that the oral microbiota was completely replaced following APDT. However, K. pneumoniae isolates before and after APDT were a single clone with 100% of genetic similarity that lost resistance phenotype for seven antibiotics of four classes. These results show that APDT can be used to treat infectious stomatitis in snakes. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Stomatal- and growth responses in willow to deficits in water- and nitrogen supply. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Stadenberg, I. [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dep. for Production Ecology

    2002-02-01

    The two plants, grown with an [N] of 100 mg per litre and subjected to a decrease in N-supply decreased their leaf relative growth rate from 22% per day to 13% per day within 2 days. Stomatal conductance did not change significantly after the decrease in N-supply. Xylem samples did not show any significant changes in its composition of mineral nutrient elements after decreased N-supply. The three plants, grown with an [N] of 50 mg per litre and subjected to a decrease in N-supply, significantly decreased leaf relative growth rate from 18.5 % to 9 % per day within 2 days. Stomatal conductance did not change significantly after the decrease in N-supply. Xylem sap samples showed a significant decrease in [K] (74 mg/l to 42 mg/l) and [S] (11 mg/l to 3.2 mg/l) within 2 days after decreased N-supply. The four plants subjected to root drying decreased their leaf relative growth rate slightly but not significantly during the drying period. Xylem samples showed a significant decrease in S-concentration (11 mg/l to 1.3 mg/l) and [NO{sub 3}] (8.0 mg/l to 1.0 mg/l), while [Fe] increased significantly (0.065 mg/l to 0.14 mg/l). Stomatal conductance is known to decrease when plants are subjected to drying of part of the root system. This was shown for Salix dasyclados in a recent publication.

  19. Analysis of the RNA species isolated from defective particles of vesicular stomatitis virus.

    Science.gov (United States)

    Adler, R; Banerjee, A K

    1976-10-01

    Serial high multiplicity passage of a cloned stock of vesicular stomatitis virus was found to generate defective interfering particles containing three size classes of RNA, with sedimentaiton coefficients of 31 S, 23 S and 19 S. The 31 S and 23 S RNA species were found to be complementary to both the 12 to 18 S and 31 S size classes of VSV mRNAs. The 19 S class of RNA was found to be partially base-paired. All three RNA species were found to contain ppAp at their 5' termini.

  20. Oral hygiene habits, denture plaque, presence of yeasts and stomatitis in institutionalised elderly in Lothian, Scotland

    DEFF Research Database (Denmark)

    Schou, L; Wight, C; Cumming, C

    1987-01-01

    The purpose of the present study was to examine the relation between oral hygiene habits, denture plaque, presence of yeasts and stomatitis in institutionalised elderly. A sample of 201 residents, 48-99 yr of age (mean age 82 yr), was selected from four different institutions in Lothian, Scotland....... Clinical recordings were carried out under standardised circumstances using well recognised indices. Information about oral hygiene habits was obtained through structured interviews conducted immediately before the clinical examination. A multivariate analysis, principal component, was carried out...

  1. Plasticity in stomatal size and density of potato leaves under different irrigation and phosphorus regimes.

    Science.gov (United States)

    Sun, Yanqi; Yan, Fei; Cui, Xiaoyong; Liu, Fulai

    2014-09-01

    The morphological features of stomata including their size and density could be modulated by environmental cues; however, the underlying mechanisms remain largely elusive. Here, the effect of different irrigation and phosphorus (P) regimes on stomatal size (SS) and stomatal density (SD) of potato leaves was investigated. The plants were grown in split-root pots under two P fertilization rates (viz., 0 and 100mgkg(-1) soil, denoted as P0 and P1, respectively) and subjected to full (FI), deficit (DI), and partial root-zone drying (PRD) irrigation regimes. Results showed that SS and SD were unresponsive to P but significantly affected by the irrigation treatment. FI plants had the largest SS, followed by DI, and PRD the smallest; and the reverse was the case for SD. Compared to FI and DI, PRD plants had significantly lower values of specific leaf area (SLA) and leaf carbon isotope discrimination (Δ(13)C) under P0. Midday leaf water potential (Ψleaf) and stomatal conductance (gs) was similar for DI and PRD, which was significantly lower than that of FI. Leaf contents of C, N, K, Ca and Mg were higher in PRD than in DI plants, particularly under P0. When analyzed across the three irrigation regimes, it was found that the P1 plants had significantly higher leaf contents of P and Mg, but significantly lower leaf K content compared to the P0 plants. Linear correlation analyses revealed that SS was positively correlated with Ψleaf and Δ(13)C; whereas SD was negatively correlated with Ψleaf, Δ(13)C and SLA, and positively correlated with leaf C, N and Ca contents. And gs was positively correlated with SS but negatively correlated with SD. Collectively, under low P level, the smaller and denser stomata in PRD plants may bring about a more efficient stomatal control over gas exchange, hereby potentially enhance water-use efficiency as exemplified by the lowered leaf Δ(13)C under fluctuating soil moisture conditions. Copyright © 2014 Elsevier GmbH. All rights reserved.

  2. Diagnosing the Role of Transpiration in the Transition from Dry to Wet Season Over the Amazon Using Satellite Observations

    Science.gov (United States)

    Wright, J. S.; Fu, R.; Yin, L.; Chae, J.

    2013-12-01

    Reanalysis data indicates that land surface evapotranspiration plays a key role in determining the timing of wet season onset over the Amazon. Here, we use satellite observations of water vapor and its stable isotopes, carbon dioxide, leaf area index, and precipitation together with reanalysis data to explore the importance of transpiration in initiating the transition from dry season to wet season over the Amazon. The growth of vegetation in this region is primarily limited by the availability of sunlight rather than the availability of soil moisture, so that the increase of solar radiation during the dry season coincides with dramatic increases in leaf area index within forested ecosystems. This period of plant growth is accompanied by uptake of carbon dioxide and enrichment of heavy isotopes in water vapor, particularly near the land surface. Reanalysis data indicate that this pre-wet season enrichment of HDO is accompanied by sharp increases in the surface latent heat flux, which eventually triggers sporadic moist convection. The transport of transpiration-enriched near-surface air by this convection causes a dramatic increase in free-tropospheric HDO in late August and September. September also marks transition points in the annual cycles of leaf area index (maximum) and carbon dioxide (minimum). The increase in convective activity during this period creates convergence, enhancing moisture transport into the region and initiating the wet season.

  3. Environmental constraints on plant transpiration and the hydrological implications in a northern high latitude upland headwater catchment

    Science.gov (United States)

    Wang, H.; Tetzlaff, D.; Soulsby, C.

    2016-12-01

    Vegetation affects water, carbon and energy transfer in the soil-plant-atmosphere system and mediates land-atmosphere interactions by altering surface albedo, roughness and soil macro-porosity, intercepting rainfall and transpiring water from soil layers. Vegetation water use (Ec) is regulated by stomata behaviour which is constrained by environmental variables including radiation, temperature, vapour pressure deficit, and soil water content. The relative influences of these variables on Ec are usually site specific reflecting climate and species differences. At a catchment scale, Ec can account for a large proportion of total evapotranspiration, and hence regulates water storage and fluxes in the soils, groundwater reservoirs and streams. In this study, we estimated transpiration from short vegetation (Calluna vulgaris) using the Maximum Entropy Production model (MEP), and measured sap flow of two forest plantations, together with meteorological variables, soil moisture and streamflow in an upland headwater catchment in northern Scotland. Our objectives were to investigate the environmental constraints on Ec in this wet humid and cool summer climate, and the hydrological responses and regulations of Ec in terms of rainfall and streamflow. Results will assist the assessment of hydrological implications of land management in terms of afforestation/deforestation.

  4. Effects of thinning on wood production, leaf area index, transpiration and canopy interception of a plantation subject to drought.

    Science.gov (United States)

    McJannet, D; Vertessy, R

    2001-08-01

    We conducted thinning trials in a 5-year-old Eucalyptus globulus ssp. globulus Labill plantation near Warrenbayne, northeastern Victoria, Australia, where soil salinization and waterlogging are common, and assessed treatment effects on tree growth, water use and survival. Half-hectare plots were thinned from the original density of 1100 stems ha(-1) to densities of 800, 600 and 400 stems ha(-1), and stem diameter increment, leaf area index, transpiration, canopy interception and depth of tree water source monitored for 21 months. Two drought periods occurred during the study, rainfall was 30% below the long-term average and there was severe mortality in all three plots. Analysis of deuterium abundance in soil and xylem water indicated that the trees accessed water only from the top meter of the soil profile. Transpiration rates were higher in the most heavily thinned plot than in the least thinned plot, which underwent a reduction in basal area during the study. The most heavily thinned plot increased in basal area by 10% during the study. Edge trees had significantly greater diameters than trees from the middle of the plots.

  5. Transpiration and assimilation of early Devonian land plants with axially symmetric telomes-simulations on the tissue level.

    Science.gov (United States)

    Konrad, W; Roth-Nebelsick, A; Kerp, H; Hass, H

    2000-09-07

    Early terrestrial ancestors of the land flora are characterized by a simple, axially symmetric habit and evolved in an atmosphere with much higher CO(2)concentrations than today. In order to gain information about the ecophysiological interrelationships of these plants, a model dealing with their gaseous exchange, which is basic to transpiration and photosynthesis, is introduced. The model is based on gas diffusion inside a porous medium and on a well-established photosynthesis model and allows for the simulation of the local gas fluxes through the various tissue layers of a plant axis. Necessary parameters consist of kinetical properties of the assimilation process and other physiological parameters (which have to be taken from extant plants), as well as physical constants and anatomical parameters which can be obtained from well-preserved fossil specimens. The model system is applied to an Early Devonian land plant, Aglaophyton major. The results demonstrate that, under an Early Devonian CO(2)concentration, A. major shows an extremely low transpiration rate and a low, but probably sufficiently high assimilation rate. Variation of the atmospheric CO(2)concentration shows that the assimilation is fully saturated even if the CO(2)content is decreased to about one-third of the initial value. This result indicates that A. major was probably able to exist under a wide range of atmospheric CO(2)concentrations. Further applications of this model system to ecophysiological studies of early land plant evolution are discussed. Copyright 2000 Academic Press.

  6. Genotypic variation in transpiration efficiency, carbon-isotope discrimination and carbon allocation during early growth in sunflower

    International Nuclear Information System (INIS)

    Virgona, J.M.; Farquhar, G.D.; Hubick, K.T.; Rawson, H.M.; Downes, R.W.

    1990-01-01

    Transpiration efficiency of dry matter production (W), carbon-isotope discrimination (Δ) and dry matter partitioning were measured on six sunflower (Helianthus annuus L.) genotypes grown for 32 days in a glasshouse. Two watering regimes, one well watered (HW) and the other delivering half the water used by the HW plants (LW), were imposed. Four major results emerged from this study: Three was significant genotypic variation in W in sunflower and this was closely reflected in Δ for both watering treatments; the low watering regime caused a decrease in Δ but no change in W; nonetheless the genotypic ranking for either Δ or W was not significantly altered by water stress; a positive correlation between W and biomass accumulation occurred among genotypes of HW plants; ρ, the ratio of total plant carbon content to leaf area, was positively correlated with W and negatively correlated with Δ. These results are discussed with reference to the connection between transpiration efficiency and plant growth, indicating that Δ can be used to select for W among young sunflower plants. However, selection for W may be accompanied by changes in other important plant growth characteristics such as ρ. 19 refs., 4 figs

  7. Genotypic variation in carbon isotope discrimination and transpiration efficiency in wheat. Leaf gas exchange and whole plant studies

    International Nuclear Information System (INIS)

    Condon, A.G.; Farquhar, G.D.; Richards, R.A.

    1990-01-01

    The relationship between carbon isotope discrimination, Δ, measured in plant dry matter and the ratio of intercellular to atmospheric partial pressures of CO 2 ,p i /p a , in leaves was examined in two glasshouse experiments using 14 wheat genotypes selected on the basis of variation in Δ of dry matter. Genotypic variation in Δ was similar in both experiments, with an average range of 1.8 x 10 -3 . Δ measured in dry matter and p i /p a measured in flag leaves were positively correlated. Variation among genotypes in p i /p a was attributed, approximately equally, to variation in leaf conductance and in photosynthetic capacity. The relationship between plant transpiration efficiency, W * (the amount of above-ground dry matter produced per unit water transpired) and Δ was was also examined. The results indicate that genotypic variation in Δ, measured in dry matter, should provide a reasonable measure of genotypic variation in long-term mean leaf p i /p a in wheat. 42 refs., 2 tabs., 5 figs

  8. Canopy-scale biophysical controls of transpiration and evaporation in the Amazon Basin

    Directory of Open Access Journals (Sweden)

    K. Mallick

    2016-10-01

    Full Text Available Canopy and aerodynamic conductances (gC and gA are two of the key land surface biophysical variables that control the land surface response of land surface schemes in climate models. Their representation is crucial for predicting transpiration (λET and evaporation (λEE flux components of the terrestrial latent heat flux (λE, which has important implications for global climate change and water resource management. By physical integration of radiometric surface temperature (TR into an integrated framework of the Penman–Monteith and Shuttleworth–Wallace models, we present a novel approach to directly quantify the canopy-scale biophysical controls on λET and λEE over multiple plant functional types (PFTs in the Amazon Basin. Combining data from six LBA (Large-scale Biosphere-Atmosphere Experiment in Amazonia eddy covariance tower sites and a TR-driven physically based modeling approach, we identified the canopy-scale feedback-response mechanism between gC, λET, and atmospheric vapor pressure deficit (DA, without using any leaf-scale empirical parameterizations for the modeling. The TR-based model shows minor biophysical control on λET during the wet (rainy seasons where λET becomes predominantly radiation driven and net radiation (RN determines 75 to 80 % of the variances of λET. However, biophysical control on λET is dramatically increased during the dry seasons, and particularly the 2005 drought year, explaining 50 to 65 % of the variances of λET, and indicates λET to be substantially soil moisture driven during the rainfall deficit phase. Despite substantial differences in gA between forests and pastures, very similar canopy–atmosphere "coupling" was found in these two biomes due to soil moisture-induced decrease in gC in the pasture. This revealed the pragmatic aspect of the TR-driven model behavior that exhibits a high sensitivity of gC to per unit change in wetness as opposed to gA that is marginally sensitive to

  9. Handling of Solid Residues

    International Nuclear Information System (INIS)

    Medina Bermudez, Clara Ines

    1999-01-01

    The topic of solid residues is specifically of great interest and concern for the authorities, institutions and community that identify in them a true threat against the human health and the atmosphere in the related with the aesthetic deterioration of the urban centers and of the natural landscape; in the proliferation of vectorial transmitters of illnesses and the effect on the biodiversity. Inside the wide spectrum of topics that they keep relationship with the environmental protection, the inadequate handling of solid residues and residues dangerous squatter an important line in the definition of political and practical environmentally sustainable. The industrial development and the population's growth have originated a continuous increase in the production of solid residues; of equal it forms, their composition day after day is more heterogeneous. The base for the good handling includes the appropriate intervention of the different stages of an integral administration of residues, which include the separation in the source, the gathering, the handling, the use, treatment, final disposition and the institutional organization of the administration. The topic of the dangerous residues generates more expectation. These residues understand from those of pathogen type that are generated in the establishments of health that of hospital attention, until those of combustible, inflammable type, explosive, radio-active, volatile, corrosive, reagent or toxic, associated to numerous industrial processes, common in our countries in development

  10. Transpiration and water use efficiency in native chilean and exotic species, a usefull tool for catchment management?

    Science.gov (United States)

    Hervé-Fernández, P.; Oyarzun, C. E.

    2012-04-01

    Land-use and forest cover change play important roles in socio-economic processes and have been linked with water supply and other ecosystem services in various regions of the world. Water yield from watersheds is a major ecosystem service for human activities but has been altered by landscape management superimposed on climatic variability and change. Sustaining ecosystem services important to humans, while providing a dependable water supply for agriculture and urban needs is a major challenge faced by managers of human-dominated or increased antropical effect over watersheds. Since water is mostly consumed by vegetation (i.e: transpiration), which strongly depends on trees physiological characteristics (i.e: foliar area, transpiration capacity) are very important. The quantity of water consumed by plantations is influenced mainly by forest characteristics (species physiology, age and management), catchment water retention capacity and meteorological characteristics. Eventhough in Chile, the forest sector accounts for 3.6% of the gross domestic product (GDP) and 12.5% of total exports (INFOR, 2003), afforestation with fast growing exotic species has ended up being socially and politically questionable because of the supposed impact on the environment and water resources. We present data of trees transpiration and water use efficiency from three headwater catchments: (a) second growth native evergreen forest (Aetoxicon punctatum, Drimys winterii, Gevuina avellana, Laureliopsis philippiana); (b) Eucalyptus globulus plantation, and (c) a mixed native deciduous (Nothofagus obliqua and some evergreen species) forest and Eucalyptus globulus and Acacia melanoxylon plantation located at the Coastal Mountain Range in southern Chile (40°S). Annual transpiration rates ranged from 1.24 ± 0.41 mol•m-2•s-1 (0.022 ± 0.009 L•m-2•s-1) for E. globulus, while the lowest observed was for L. philippiana 0.44 ± 0.31 mol•m-2•s-1 (0.008 ± 0.006 L•m-2•s-1). However

  11. Coronatine inhibits stomatal closure through guard cell-specific inhibition of NADPH oxidase-dependent ROS production

    Directory of Open Access Journals (Sweden)

    Laila Toum

    2016-12-01

    Full Text Available Microbes trigger stomatal closure through microbe-associated molecular patterns (MAMPs. The bacterial pathogen Pseudomonas syringae pv. tomato (Pst synthesizes the polyketide toxin coronatine, which inhibits stomatal closure by MAMPs and the hormone abscisic acid (ABA. The mechanism by which coronatine, a jasmonic acid-isoleucine analog, achieves this effect is not completely clear. Reactive oxygen species (ROS are essential second messengers in stomatal immunity, therefore we investigated the possible effect of coronatine on their production. We found that coronatine inhibits NADPH oxidase-dependent ROS production induced by ABA, and by the flagellin-derived peptide flg22. This toxin also inhibited NADPH oxidase-dependent stomatal closure induced by darkness, however it failed to prevent stomatal closure by exogenously applied H2O2 or by salicylic acid, which induces ROS production through peroxidases. Contrary to what was observed on stomata, coronatine did not affect the oxidative burst induced by flg22 in leaf discs. Additionally, we observed that in NADPH oxidase mutants atrbohd and atrbohd/f, as well as in guard cell ABA responsive but flg22 insensitive mutants mpk3, mpk6, npr1-3 and lecrk-VI.2-1, the inhibition of ABA stomatal responses by both coronatine and the NADPH oxidase inhibitor diphenylene iodonium was markedly reduced. Interestingly, coronatine still impaired ABA-induced ROS synthesis in mpk3, mpk6, npr1-3 and lecrk-VI.2-1, suggesting a possible feedback regulation of ROS on other guard cell ABA signalling elements in these mutants. Altogether our results show that inhibition of NADPH oxidase-dependent ROS synthesis in guard cells plays an important role during endophytic colonization by Pst through stomata.

  12. Differences in the response sensitivity of stomatal index to atmospheric CO2 among four genera of Cupressaceae conifers.

    Science.gov (United States)

    Haworth, Matthew; Heath, James; McElwain, Jennifer C

    2010-03-01

    The inverse relationship between stomatal density (SD: number of stomata per mm(2) leaf area) and atmospheric concentration of CO2 ([CO2]) permits the use of plants as proxies of palaeo-atmospheric CO2. Many stomatal reconstructions of palaeo-[CO2] are based upon multiple fossil species. However, it is unclear how plants respond to [CO2] across genus, family or ecotype in terms of SD or stomatal index (SI: ratio of stomata to epidermal cells). This study analysed the stomatal numbers of conifers from the ancient family Cupressaceae, in order to examine the nature of the SI-[CO2] relationship, and potential implications for stomatal reconstructions of palaeo-[CO2]. Methods Stomatal frequency measurements were taken from historical herbarium specimens of Athrotaxis cupressoides, Tetraclinis articulata and four Callitris species, and live A. cupressoides grown under CO2-enrichment (370, 470, 570 and 670 p.p.m. CO2). T. articulata, C. columnaris and C. rhomboidea displayed significant reductions in SI with rising [CO2]; by contrast, A. cupressoides, C. preissii and C. oblonga show no response in SI. However, A. cupressoides does reduce SI to increases in [CO2] above current ambient (approx. 380 p.p.m. CO2). This dataset suggests that a shared consistent SI-[CO2] relationship is not apparent across the genus Callitris. Conclusions The present findings suggest that it is not possible to generalize how conifer species respond to fluctuations in [CO2] based upon taxonomic relatedness or habitat. This apparent lack of a consistent response, in conjunction with high variability in SI, indicates that reconstructions of absolute palaeo-[CO2] based at the genus level, or upon multiple species for discrete intervals of time are not as reliable as those based on a single or multiple temporally overlapping species.

  13. Non-stomatal exchange in ammonia dry deposition models: comparison of two state-of-the-art approaches

    Directory of Open Access Journals (Sweden)

    F. Schrader

    2016-10-01

    Full Text Available The accurate representation of bidirectional ammonia (NH3 biosphere–atmosphere exchange is an important part of modern air quality models. However, the cuticular (or external leaf surface pathway, as well as other non-stomatal ecosystem surfaces, still pose a major challenge to translating our knowledge into models. Dynamic mechanistic models including complex leaf surface chemistry have been able to accurately reproduce measured bidirectional fluxes in the past, but their computational expense and challenging implementation into existing air quality models call for steady-state simplifications. Here we qualitatively compare two semi-empirical state-of-the-art parameterizations of a unidirectional non-stomatal resistance (Rw model after Massad et al. (2010, and a quasi-bidirectional non-stomatal compensation-point (χw model after Wichink Kruit et al. (2010, with NH3 flux measurements from five European sites. In addition, we tested the feasibility of using backward-looking moving averages of air NH3 concentrations as a proxy for prior NH3 uptake and as a driver of an alternative parameterization of non-stomatal emission potentials (Γw for bidirectional non-stomatal exchange models. Results indicate that the Rw-only model has a tendency to underestimate fluxes, while the χw model mainly overestimates fluxes, although systematic underestimations can occur under certain conditions, depending on temperature and ambient NH3 concentrations at the site. The proposed Γw parameterization revealed a clear functional relationship between backward-looking moving averages of air NH3 concentrations and non-stomatal emission potentials, but further reduction of uncertainty is needed for it to be useful across different sites. As an interim solution for improving flux predictions, we recommend reducing the minimum allowed Rw and the temperature response parameter in the unidirectional model and revisiting the temperature-dependent Γw parameterization

  14. [Residual neuromuscular blockade].

    Science.gov (United States)

    Fuchs-Buder, T; Schmartz, D

    2017-06-01

    Even small degrees of residual neuromuscular blockade, i. e. a train-of-four (TOF) ratio >0.6, may lead to clinically relevant consequences for the patient. Especially upper airway integrity and the ability to swallow may still be markedly impaired. Moreover, increasing evidence suggests that residual neuromuscular blockade may affect postoperative outcome of patients. The incidence of these small degrees of residual blockade is relatively high and may persist for more than 90 min after a single intubating dose of an intermediately acting neuromuscular blocking agent, such as rocuronium and atracurium. Both neuromuscular monitoring and pharmacological reversal are key elements for the prevention of postoperative residual blockade.

  15. TENORM: Wastewater Treatment Residuals

    Science.gov (United States)

    Water and wastes which have been discharged into municipal sewers are treated at wastewater treatment plants. These may contain trace amounts of both man-made and naturally occurring radionuclides which can accumulate in the treatment plant and residuals.

  16. Residuation in orthomodular lattices

    Directory of Open Access Journals (Sweden)

    Chajda Ivan

    2017-04-01

    Full Text Available We show that every idempotent weakly divisible residuated lattice satisfying the double negation law can be transformed into an orthomodular lattice. The converse holds if adjointness is replaced by conditional adjointness. Moreover, we show that every positive right residuated lattice satisfying the double negation law and two further simple identities can be converted into an orthomodular lattice. In this case, also the converse statement is true and the corresponence is nearly one-to-one.

  17. Continent-Wide Decrease of Stomatal Conductance in Vegetation During Large Droughts of the Recent Decade

    Science.gov (United States)

    Peters, W.; van der Velde, I.; Miller, J. B.; Schaefer, K. M.; Tans, P. P.; Vaughn, B. H.; White, J. W. C.; van der Molen, M. K.

    2015-12-01

    Severe droughts in the Northern Hemisphere caused widespread decline of agricultural yield, reduction of forest carbon uptake, and increased CO₂ growth rates in the atmosphere during the past decade. Plants respond to droughts by partially closing their stomata to limit their evaporative water loss, at the expense of carbon uptake by photosynthesis. Here we present new evidence on this drought response of terrestrial vegetation derived from year-to-year changes in the 13C/12C stable isotope ratio in atmospheric CO2. Observations from more than 50,000 flask samples from the NOAA Global Greenhouse Gas Reference Network suggest a strong decrease in stomatal conductance in vegetation that is highly correlated (see green line in the figure) with reductions of net carbon uptake over the Northern Hemisphere. This correlation is driven by severe drought conditions over areas several million km2 in size in Europe (2003, 2006), Russia (2010), and the United States (2002). This spatially integrated vegetation drought response at this scale can not be measured from laboratory experiments or field studies and the atmosphere thus offers a unique perspective on large-scale vegetation drought dynamics. A widely used stomatal conductance parameterization used in our study as well as many current climate models underestimate this observed decrease in carbon and water exchange during droughts (black and blue lines in the figure). The global δ13C record could provide a new opportunity to improve interannual drought dynamics in coupled vegetation-atmosphere models for CO2.

  18. Protective efficacy of a recombinant Newcastle disease virus expressing glycoprotein of vesicular stomatitis virus in mice.

    Science.gov (United States)

    Zhang, Minmin; Ge, Jinying; Li, Xiaofang; Chen, Weiye; Wang, Xijun; Wen, Zhiyuan; Bu, Zhigao

    2016-02-24

    Vesicular stomatitis virus (VSV) causes severe losses to the animal husbandry industry. In this study, a recombinant Newcastle disease virus (NDV) expressing the glycoprotein (G) of VSV (rL-VSV-G) was constructed and its pathogenicity and immune protective efficacy in mouse were evaluated. In pathogenicity evaluation test, the analysis of the viral distribution in mouse organs and body weight change showed that rL-VSV-G was safe in mice. In immune protection assay, the recombinant rL-VSV-G triggered a high titer of neutralizing antibodies against VSV. After challenge, the wild-type (wt) VSV viral load in mouse organs was lower in rL-VSV-G group than that in rLaSota groups. wt VSV was not detected in the blood, liver, or kidneys of mice, whereas it was found in these tissues in control groups. The mice body weight had no significant change after challenge in the rL-VSV-G group. Additionally, suckling mice produced from female mice immunized with rL-VSV-G were partially protected from wt VSV challenge. These results demonstrated that rL-VSV-G may be a suitable candidate vaccine against vesicular stomatitis (VS).

  19. Stomatal conductance of semi-natural Mediterranean grasslands: Implications for the development of ozone critical levels

    International Nuclear Information System (INIS)

    Alonso, R.; Bermejo, V.; Sanz, J.; Valls, B.; Elvira, S.; Gimeno, B.S.

    2007-01-01

    Intra-genus and intra-specific variation and the influence of nitrogen enrichment on net assimilation and stomatal conductance of some annual Trifolium species of Mediterranean dehesa grasslands were assessed under experimental conditions. Also gas exchange rates were compared between some Leguminosae and Poaceae species growing in the field in a dehesa ecosystem in central Spain. The results showed that the previously reported different O 3 sensitivity of some Trifolium species growing in pots does not seem to be related to different maximum g s values. In addition, no clear differences on gas exchange rates could be attributed to Leguminosae and Poaceae families growing in the field, with intra-genus variation being more important than differences found between families. Further studies are needed to increase the database for developing a flux-based approach for setting O 3 critical levels for semi-natural Mediterranean species. - The stomatal conductance model incorporated within the EMEP DO 3 SE deposition module needs to be re-parameterised for Mediterranean semi-natural vegetation

  20. Grasshoppers (Orthoptera: Acrididae) could serve as reservoirs and vectors of vesicular stomatitis virus.

    Science.gov (United States)

    Nunamaker, Richard A; Lockwood, Jeffrey A; Stith, Charles E; Campbell, Corey L; Schell, Scott P; Drolet, Barbara S; Wilson, William C; White, David M; Letchworth, Geoffrey J

    2003-11-01

    Vesicular stomatitis (VS) is an economically devastating disease of livestock in the Americas. Despite strong circumstantial evidence for the role of arthropods in epizootics, no hematophagous vector explains the field evidence. Based on the spatiotemporal association of grasshopper outbreaks and VS epizootics, we investigated the potential role of these insects as vectors and reservoirs of the disease. The critical steps in the grasshopper-bovine transmission cycle were demonstrated, including 1) 62% of grasshoppers [Melanoplus sanguinipes (F.)] fed vesicular stomatitis virus (VSV) from cell culture became infected, with titers reaching 40,000 times the inoculative dose; 2) 40% of grasshoppers that cannibalized VSV-infected grasshopper cadavers became infected, amplifying virus up to 1,000-fold; 3) one of three cattle consuming VSV-infected grasshopper cadavers contracted typical VS and shed virus in saliva; and 4) 15% of grasshoppers became infected when fed saliva from this infected cow. The ecological conditions and biological processes necessary for these transmissions to occur are present throughout much of the Americas. Field studies will be required to show these findings are relevant to the natural epidemiology of VSV.

  1. Atmospheric CO2 Dynamics During the Holocene Revealed by Stomatal Frequency Analysis

    Science.gov (United States)

    Wagner, F.; McElwain, J.; Kouwenberg, L. L.; Beerling, D. J.; Kuerschner, W. M.; Visscher, H.

    2002-12-01

    A variety of land plants are capable of sustained adjustment of the number of leaf stomata (gas pores) to changing atmospheric CO2 concentrations. Measured on fossil leaves, and calibrated against modern training sets, stomatal frequency data are increasingly applied as a proxy for palaeo-atmospheric CO2 reconstructions. These data demonstrate with high temporal resolution and accuracy that century-scale CO2 fluctuations contributed to Holocene climate evolution. We here present a composite record of Holocene atmospheric CO2 concentrations based on stomatal frequency analysis. The CO2 estimations are derived from fossil leaf assemblages preserved in peat and lake deposits in Europe, Canada and the USA. The leaf material studied originates from deciduous trees, conifers and shrubs. Independent of site locality and plant species studied, CO2 reconstructions from the individual sections correspond well in the overlapping parts of the records. The combined data sets provide convincing evidence for a highly dynamic atmospheric CO2 regime during the Holocene. A fast CO2 increase occurs at the Younger Dryas / Holocene transition. Short-term CO2 reductions are associated with three major cool pulses known from marine and terrestrial records: the Preboreal Oscillation, the 8.2 kyr event and the Little Ice Age.

  2. Stomatal conductance of semi-natural Mediterranean grasslands: Implications for the development of ozone critical levels

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, R. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain)]. E-mail: rocio.alonso@ciemat.es; Bermejo, V. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain); Sanz, J. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain); Valls, B. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain); Elvira, S. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain); Gimeno, B.S. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain)

    2007-04-15

    Intra-genus and intra-specific variation and the influence of nitrogen enrichment on net assimilation and stomatal conductance of some annual Trifolium species of Mediterranean dehesa grasslands were assessed under experimental conditions. Also gas exchange rates were compared between some Leguminosae and Poaceae species growing in the field in a dehesa ecosystem in central Spain. The results showed that the previously reported different O{sub 3} sensitivity of some Trifolium species growing in pots does not seem to be related to different maximum g {sub s} values. In addition, no clear differences on gas exchange rates could be attributed to Leguminosae and Poaceae families growing in the field, with intra-genus variation being more important than differences found between families. Further studies are needed to increase the database for developing a flux-based approach for setting O{sub 3} critical levels for semi-natural Mediterranean species. - The stomatal conductance model incorporated within the EMEP DO{sub 3}SE deposition module needs to be re-parameterised for Mediterranean semi-natural vegetation.

  3. DIPHTHERITIC STOMATITIS IN YELLOW-EYED PENGUINS (MEGADYPTES ANTIPODES) IN NEW ZEALAND.

    Science.gov (United States)

    Alley, Maurice R; Suepaul, Rod B; McKinlay, Bruce; Young, Melanie J; Wang, Jianning; Morgan, Kerri J; Hunter, Stuart A; Gartrell, Brett D

    2017-01-01

    Diphtheritic stomatitis is a seasonal disease that has been recognized as a syndrome in Yellow-eyed Penguin ( Megadyptes antipodes ) chicks in New Zealand for >10 yr. It was present in about 50% of 234 chicks examined since 2002 and is characterized by a thick serocellular exudate in the oral cavity of 1-4-wk-old chicks. The syndrome includes inanition, weight loss, and death in many affected birds. Microscopically, the lesions varied in severity. Most affected chicks had severe, locally extensive, ulcerative stomatitis with large amounts of exudate containing numerous bacteria; a smaller number had mild focal lesions with smaller amounts of exudate and bacteria. Although Corynebacterium amycolatum has been consistently isolated from the oral lesions, it was also present in the oral cavity of 34% of normal adult penguins and their chicks and is not known to possess diphtheritic toxins. A primary viral pathogen was therefore suspected, and intracytoplasmic inclusion bodies were occasionally seen in oral mucosal epithelial cells. No herpesvirus DNA was detected with PCR. Avipoxvirus DNA and an unidentified virus-like agent were detected in some early oral lesions, but could not be confirmed in subsequent testing. Electron microscopy on early affected epithelium with intracytoplasmic inclusion bodies was unrewarding. Our findings raise the possibility that the disease is caused by an unknown primary virus infection followed by secondary Corynebacterium invasion, but this requires confirmation. The means of transmission has not been established but insect vectors are suspected.

  4. OsPRX2 contributes to stomatal closure and improves potassium deficiency tolerance in rice.

    Science.gov (United States)

    Mao, Xiaohui; Zheng, Yanmei; Xiao, Kaizhuan; Wei, Yidong; Zhu, Yongsheng; Cai, Qiuhua; Chen, Liping; Xie, Huaan; Zhang, Jianfu

    2018-01-01

    Peroxiredoxins (Prxs) which are thiol-based peroxidases have been implicated in the toxic reduction and intracellular concentration regulation of hydrogen peroxide. In Arabidopsis thaliana At2-CysPrxB (At5g06290) has been demonstrated to be essential in maintaining the water-water cycle for proper H 2 O 2 scavenging. Although the mechanisms of 2-Cys Prxs have been extensively studied in Arabidopsis thaliana, the function of 2-Cys Prxs in rice is unclear. In this study, a rice homologue gene of At2-CysPrxB, OsPRX2 was investigated aiming to characterize the effect of 2-Cys Prxs on the K + -deficiency tolerance in rice. We found that OsPRX2 was localized in the chloroplast. Overexpressed OsPRX2 causes the stomatal closing and K + -deficiency tolerance increasing, while knockout of OsPRX2 lead to serious defects in leaves phenotype and the stomatal opening under the K + -deficiency tolerance. Detection of K + accumulation, antioxidant activity of transgenic plants under the starvation of potassium, further confirmed that OsPRX2 is a potential target for engineering plants with improved potassium deficiency tolerance. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Characterization of Hospital Residuals

    International Nuclear Information System (INIS)

    Blanco Meza, A.; Bonilla Jimenez, S.

    1997-01-01

    The main objective of this investigation is the characterization of the solid residuals. A description of the handling of the liquid and gassy waste generated in hospitals is also given, identifying the source where they originate. To achieve the proposed objective the work was divided in three stages: The first one was the planning and the coordination with each hospital center, in this way, to determine the schedule of gathering of the waste can be possible. In the second stage a fieldwork was made; it consisted in gathering the quantitative and qualitative information of the general state of the handling of residuals. In the third and last stage, the information previously obtained was organized to express the results as the production rate per day by bed, generation of solid residuals for sampled services, type of solid residuals and density of the same ones. With the obtained results, approaches are settled down to either determine design parameters for final disposition whether for incineration, trituration, sanitary filler or recycling of some materials, and storage politics of the solid residuals that allow to determine the gathering frequency. The study concludes that it is necessary to improve the conditions of the residuals handling in some aspects, to provide the cleaning personnel of the equipment for gathering disposition and of security, minimum to carry out this work efficiently, and to maintain a control of all the dangerous waste, like sharp or polluted materials. In this way, an appreciable reduction is guaranteed in the impact on the atmosphere. (Author) [es

  6. Modeling daily gas exchange of a Douglas-fir forest : comparison of three stomatal conductance models with and without a soil water stress function

    NARCIS (Netherlands)

    Wijk, van M.T.; Dekker, S.C.; Bouten, W.; Bosveld, F.C.; Kohsiek, W.; Kramer, K.; Mohren, G.M.J.

    2000-01-01

    Modeling stomatal conductance is a key element in predicting tree growth and water use at the stand scale. We compared three commonly used models of stomatal conductance, the Jarvis-Loustau, Ball-Berry and Leuning models, for their suitability for incorporating soil water stress into their

  7. Diel trends in stomatal response to ozone and water deficit: a unique relationship of midday values to growth and allometry in Pima cotton?

    Science.gov (United States)

    D. A. Grantz; R. Paudel; H.-B. Vu; A. Shrestha; Nancy Grulke; L. J. De Kok

    2015-01-01

    Plant responses to ozone (O3) and water deficit (WD) are commonly observed, although less is known about their interaction. Stomatal conductance (gs) is both an impact of these stressors and a protective response to them. Stomatal closure reduces inward flux of O3 and outward flux...

  8. A reduced order model to analytically infer atmospheric CO2 concentration from stomatal and climate data

    Science.gov (United States)

    Konrad, Wilfried; Katul, Gabriel; Roth-Nebelsick, Anita; Grein, Michaela

    2017-06-01

    To address questions related to the acceleration or deceleration of the global hydrological cycle or links between the carbon and water cycles over land, reliable data for past climatic conditions based on proxies are required. In particular, the reconstruction of palaeoatmospheric CO2 content (Ca) is needed to assist the separation of natural from anthropogenic Ca variability and to explore phase relations between Ca and air temperature Ta time series. Both Ta and Ca are needed to fingerprint anthropogenic signatures in vapor pressure deficit, a major driver used to explain acceleration or deceleration phases in the global hydrological cycle. Current approaches to Ca reconstruction rely on a robust inverse correlation between measured stomatal density in leaves (ν) of many plant taxa and Ca. There are two methods that exploit this correlation: The first uses calibration curves obtained from extant species assumed to represent the fossil taxa, thereby restricting the suitable taxa to those existing today. The second is a hybrid eco-hydrological/physiological approach that determines Ca with the aid of systems of equations based on quasi-instantaneous leaf-gas exchange theories and fossil stomatal data collected along with other measured leaf anatomical traits and parameters. In this contribution, a reduced order model (ROM) is proposed that derives Ca from a single equation incorporating the aforementioned stomatal data, basic climate (e.g. temperature), estimated biochemical parameters of assimilation and isotope data. The usage of the ROM is then illustrated by applying it to isotopic and anatomical measurements from three extant species. The ROM derivation is based on a balance between the biochemical demand and atmospheric supply of CO2 that leads to an explicit expression linking stomatal conductance to internal CO2 concentration (Ci) and Ca. The resulting expression of stomatal conductance from the carbon economy of the leaf is then equated to another

  9. Diel trends in stomatal response to ozone and water deficit: a unique relationship of midday values to growth and allometry in Pima cotton?

    Science.gov (United States)

    Grantz, D A; Paudel, R; Vu, H-B; Shrestha, A; Grulke, N

    2016-01-01

    Plant responses to ozone (O3 ) and water deficit (WD) are commonly observed, although less is known about their interaction. Stomatal conductance (gs ) is both an impact of these stressors and a protective response to them. Stomatal closure reduces inward flux of O3 and outward flux of water. Stomatal measurements are generally obtained at midday when gas exchange is maximal, but these may not be adequate surrogates for stomatal responses observed at other times of day, nor for non-stomatal responses. Here, we find in Pima cotton that stomatal responses to O3 observed at midday do not reflect responses at other times. Stomata were more responsive to O3 and WD near midday, despite being at quasi-steady state, than during periods of active opening or closing in morning or evening. Stomatal responsivity to O3 was not coincident with maximum gas exchange or with periods of active regulation, but coincident with plant sensitivity to O3 previously determined in this cultivar. Responses of pigmentation and shoot productivity were more closely related to stomatal responses at midday than to responses at other times of day under well-watered (WW) conditions, reflecting higher stomatal responsivity, sensitivity to O3 , and magnitude of midday gs . Under WD conditions, shoot responses were more closely related to early morning gs. Root responses were more closely related to early morning gs under both WW and WD. Responses of stomata to O3 at midday were not good surrogates for stomatal responses early or late in the day, and may not adequately predicting O3 flux under WD or when maximum ambient concentrations do not occur near midday. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

  10. Stomatal behavior and components of the antioxidative system in coffee plants under water stress Comportamento estomático e componentes do sistema antioxidante em cafeeiros sob estresse hídrico

    Directory of Open Access Journals (Sweden)

    Sidnei Deuner

    2011-02-01

    Full Text Available Coffee (Coffea arabica plants show a positive relationship between stomatal closure and formation and accumulation of H2O2. However, for coffee plants under water restriction such relationship has never been studied. The objective of the present study was evaluate the stomatal movement and the antioxidant capacity of coffee seedlings under different water regimes. Eight months old coffee seedlings of cv. Catuaí IAC 99 were submitted to field capacity, gradual and total suspension of irrigation during a period of 21 days. Evaluations of leaf water potential (Ψw were performed in the beginning of the morning, and stomatal resistance, transpiration rate and vapor pressure deficit were determined at 10 am and 5 pm. All biochemical and enzymatic determinations were performed in leaves collected at 5 pm. Evaluations and samplings were performed at three days intervals. There was no variation in Ψw during the evaluated period for plants in field capacity. However, an expressive decrease of Ψw following day 12, reaching values near -2.5 MPa at the end of the experiment was observed for plants submitted to gradual suspension of irrigation. For plants submitted to total suspension of irrigation, Ψw decreases after the sixth day, reaching -2.5 MPa at day 15. The decay of Ψw in plants submitted to gradual and total suspension of irrigation reflected in increased stomatal resistance and in a decreased transpiration rate leading to an increase in hydrogen peroxide formation and, on final stages, increase in lipid peroxidation. As a conclusion, an increase in the activity of antioxidant enzymes as well as in the levels of ascorbate and dehydroascorbate was observed, which act in the detoxification of free radicals formed as result of the water stress.Para o cafeeiro (Coffea arabica existe uma comprovada relação positiva entre fechamento estomático e formação e acúmulo de H2O2. Entretanto, tal relação para a cultura sob restrição hídrica ainda

  11. Imaging the experiments on respiration and transpiration of Lavoisier and Séguin: two unknown drawings by Madame Lavoisier.

    Science.gov (United States)

    Beretta, Marco

    2012-01-01

    This paper presents two hitherto unknown drawings by Marie-Anne-Pierrette Lavoisier dating to the early 1790s that illustrate the experiments on respiration and transpiration of her husband Antoine-Laurent Lavoisier and his assistant Armand Séguin. These works may be associated with the well-known sepia drawings that were published for the first time by Edouard Grimaux in 1888. Details contained in these newly discovered drawings by M.me Lavoisier provide fresh evidence as to the nature and aims of Lavoisier's innovative experiments. As we will show, these drawings were intended to illustrate the collection of papers on respiration being prepared by Lavoisier for his Mémoires de physique et de chimie (1792-1805).

  12. Integrating modelling and phenotyping approaches to identify and screen complex traits - Illustration for transpiration efficiency in cereals.

    Science.gov (United States)

    Chenu, K; van Oosterom, E J; McLean, G; Deifel, K S; Fletcher, A; Geetika, G; Tirfessa, A; Mace, E S; Jordan, D R; Sulman, R; Hammer, G L

    2018-02-21

    Following advances in genetics, genomics, and phenotyping, trait selection in breeding is limited by our ability to understand interactions within the plants and with their environments, and to target traits of most relevance for the target population of environments. We propose an integrated approach that combines insights from crop modelling, physiology, genetics, and breeding to identify traits valuable for yield gain in the target population of environments, develop relevant high-throughput phenotyping platforms, and identify genetic co