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Sample records for net transpiration water

  1. 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.

  2. Moderate water stress from regulated deficit irrigation decreases transpiration similarly to net carbon exchange in grapevine canopies

    Science.gov (United States)

    To determine the effects of timing and extent of regulated deficit irrigation (RDI) on grapevine (Vitis vinifera) canopies, whole-canopy transpiration (TrV) and canopy conductance to water vapor (gc) were calculated from whole-vine gas exchange near key stages of fruit development. The vines were ma...

  3. Terrestrial water fluxes dominated by transpiration.

    Science.gov (United States)

    Jasechko, Scott; Sharp, Zachary D; Gibson, John J; Birks, S Jean; Yi, Yi; Fawcett, Peter J

    2013-04-18

    Renewable fresh water over continents has input from precipitation and losses to the atmosphere through evaporation and transpiration. Global-scale estimates of transpiration from climate models are poorly constrained owing to large uncertainties in stomatal conductance and the lack of catchment-scale measurements required for model calibration, resulting in a range of predictions spanning 20 to 65 per cent of total terrestrial evapotranspiration (14,000 to 41,000 km(3) per year) (refs 1, 2, 3, 4, 5). Here we use the distinct isotope effects of transpiration and evaporation to show that transpiration is by far the largest water flux from Earth's continents, representing 80 to 90 per cent of terrestrial evapotranspiration. On the basis of our analysis of a global data set of large lakes and rivers, we conclude that transpiration recycles 62,000 ± 8,000 km(3) of water per year to the atmosphere, using half of all solar energy absorbed by land surfaces in the process. We also calculate CO2 uptake by terrestrial vegetation by connecting transpiration losses to carbon assimilation using water-use efficiency ratios of plants, and show the global gross primary productivity to be 129 ± 32 gigatonnes of carbon per year, which agrees, within the uncertainty, with previous estimates. The dominance of transpiration water fluxes in continental evapotranspiration suggests that, from the point of view of water resource forecasting, climate model development should prioritize improvements in simulations of biological fluxes rather than physical (evaporation) fluxes.

  4. 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...

  5. Studies on transpiration rates and tritium concentration in transpired water in some plant species at Kaiga site

    International Nuclear Information System (INIS)

    Selvi, S.B.; Ravi, P.M.; Hegde, A.G.

    2005-01-01

    Transpiration is the driving force for uptake of water and hence that of tritiated water from environment. Transpiration rates and tritium concentration in transpired water in some plants at Kaiga site were estimated. Good correlation was observed between transpiration rates with humidity, temperature and leaf surface area. Transpiration rates varied seasonally and diurnally due to the influence of interdependent parameters such as temperature, humidity, water availability, etc. The ratio between the tritium concentrations in transpired plant water to that in air moisture ranged from 0.1 to 0.2. (author)

  6. Net zero water

    CSIR Research Space (South Africa)

    Lindeque, M

    2013-01-01

    Full Text Available the national grid. The unfortunate situation with water is that there is no replacement technology for water. Water can be supplied from many different sources. A net zero energy development will move closer to a net zero water development by reducing...

  7. African Mahogany transpiration with Granier method and water table lysimeter

    Directory of Open Access Journals (Sweden)

    Ana C. O. Sérvulo

    Full Text Available ABSTRACT The thermal dissipation probe (Granier method is useful in the water deficit monitoring and irrigation management of African Mahogany, but its model needs proper adjustment. This paper aimed to adjust and validate the Granier sap flux model to estimate African Mahogany transpiration, measure transpiration using lysimeter and relate it to atmospheric water demand. Weather conditions, transpiration and sap flux were monitored in three units of 2.5-year-old African Mahogany trees in constant water table lysimeter, in Goiânia, GO. Sapwood area (SA, leaf area (LA, transpiration measured by lysimeter (TLYS and estimated by sap flux (TSF were evaluated. The SA comprised 55.24% of the trunk’s transversal section. The LA varied from 11.95 to 10.66 m2. TLYS and TSF varied from 2.94 to 29.31 and from 0.94 to 15.45 L d-1, respectively. The original model underestimated transpiration by 44.4%, being the adjusted equation F = 268.25 . k1.231. SA was significant (F < 0.05. Due the root confinement, the transpiration showed low correlation, but positive, with the atmospheric water demand.

  8. Reduction of plant water consumption through anti-transpirants foliar application in tomato plants (Solanum lycopersicum L.)

    Science.gov (United States)

    Optimizing water use efficiency (WUE) is a crucial goal. However, water savings must not be made at the expense of yield and fruit quality in order to secure economical sustainability for producers. The impact of different anti-transpirants (ATS) on WUE, water consumption (WC), net carbon assimilati...

  9. 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.

  10. Forest Transpiration: Resolving Species-Specific Root Water Uptake Patterns

    Science.gov (United States)

    Blume, T.; Heidbuechel, I.; Simard, S.; Guntner, A.; Weiler, M.; Stewart, R. D.

    2016-12-01

    Transpiration and its spatio-temporal variability are still not fully understood, despite their importance for the global water cycle. This is in part due to our inability to measure transpiration comprehensively. Transpiration is usually either estimated with empirical equations based on climatic variables and crop factors, by measuring sap velocities, estimating sap wood area and scaling up to the forest stand based on a number of assumptions or by measuring the integral signal across a footprint with eddy flux towers. All these methods are focused on the cumulated loss of water to the atmosphere and do not provide information on where this water is coming from. In this study, spatio-temporal variability of root water uptake was investigated in a forest in the northeastern German lowlands. The soils are sandy and the depth of the unsaturated zone ranges from 1 to 30 m. We estimated root water uptake from different soil depths, from 0.1 m down to 2 m, based on diurnal fluctuations in soil moisture content during rain-free days. The 15 field sites cover different topographic positions and forest stands: 4 pure stands of both mature and young beech and pine and 9 mixed stands. The resulting daily data set of root water uptake shows that the forest stands differ in total amounts as well as in uptake depth distributions. Temporal dynamics of signal strength within the profile suggest a locally shifting spatial distribution of uptake that changes with water availability. The relationship of these depth-resolved uptake rates to overall soil water availability varies considerably between tree species. Using the physically-based soil hydrological model HYDRUS we investigated to what extent the observed patterns in uptake can be related to soil physical relationships alone and where tree species-specific aspects come into play. We furthermore used the model to test assumptions and estimate uncertainties of this soil moisture based estimation of plant water uptake. The

  11. 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.

  12. Evolution of Corn Transpiration and Leaf Water Potential During Sprinkler Irrigation

    OpenAIRE

    Martínez-Cob, Antonio; Fernández-Navajas, Julián; Durán, Víctor; Cavero Campo, José

    2009-01-01

    Corn (Zea mays L.) transpiration during daytime solid-set sprinkler irrigation was analyzed on two neighbouring subplots to determine the effect of the transpiration reduction on water application efficiency. During each irrigation event, one subplot was irrigated (moist treatment) while the other was not (dry treatment). Transpiration rates were determined at each subplot by the heat balance method (Dynamax Flow4 System) before, during and after the irrigations. During irri...

  13. [Experimental study on crop photosynthesis, transpiration and high efficient water use].

    Science.gov (United States)

    Wang, Huixiao; Liu, Changming

    2003-10-01

    It is well known that the development of water-saving agriculture is a strategic choice for getting rid of the crisis of water shortage. In this paper, the crop photosynthesis, transpiration, stomatic behavior, and their affecting factors were studied in view of increasing the crop water use efficiency. The experimental results showed that there was a parabola relationship between photosynthesis and transpiration. The transpiration at the maximum photosynthesis was a critical value, above which, transpiration was the luxurious part. The luxurious transpiration could be controlled without affecting photosynthetic production. It is possible that the measures for increasing stomatic resistance and preventing transpiration could save water, and improve photosynthesis and yield as well. The photosynthesis rate increased with photosynthetic active radiation, and the light saturation point for photosynthesis existed. The light saturation point of dry treatment was much lower than that of wet treatment, and the relationship between transpiration and radiation was linear. When the photosynthetic active radiation was bigger than 1,000 mumol.m-2.s-1, some treatments could be carried out for decreasing transpiration and improving photosynthesis.

  14. Rootstock control of scion transpiration and its acclimation to water deficit are controlled by different genes.

    Science.gov (United States)

    Marguerit, Elisa; Brendel, Oliver; Lebon, Eric; Van Leeuwen, Cornelis; Ollat, Nathalie

    2012-04-01

    The stomatal control of transpiration is one of the major strategies by which plants cope with water stress. Here, we investigated the genetic architecture of the rootstock control of scion transpiration-related traits over a period of 3 yr. The rootstocks studied were full sibs from a controlled interspecific cross (Vitis vinifera cv. Cabernet Sauvignon × Vitis riparia cv. Gloire de Montpellier), onto which we grafted a single scion genotype. After 10 d without stress, the water supply was progressively limited over a period of 10 d, and a stable water deficit was then applied for 15 d. Transpiration rate was estimated daily and a mathematical curve was fitted to its response to water deficit intensity. We also determined δ(13) C values in leaves, transpiration efficiency and water extraction capacity. These traits were then analysed in a multienvironment (year and water status) quantitative trait locus (QTL) analysis. Quantitative trait loci, independent of year and water status, were detected for each trait. One genomic region was specifically implicated in the acclimation of scion transpiration induced by the rootstock. The QTLs identified colocalized with genes involved in water deficit responses, such as those relating to ABA and hydraulic regulation. Scion transpiration rate and its acclimation to water deficit are thus controlled genetically by the rootstock, through different genetic architectures. © 2012 INRA. New Phytologist © 2012 New Phytologist Trust.

  15. Measurement of transpiration and biomass of coconut palm with tritiated water

    International Nuclear Information System (INIS)

    Vasu, K.; Wahid, P.A.

    1990-01-01

    Measurements of transpiration rate and biomass of coconut palm have been made using tritiated water as a tracer. The method of tracer injection into the coconut trunk and the extraction of tritiated water from coconut leaves are outlined. The transpiration rate of the tree selected for the study was found to be 2.2 litres/hour with a total biomass of 172 kg. (author). 8 refs., 3 tabs

  16. 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.

  17. 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

  18. 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

  19. Transpiration and water-use efficiency in mixed-species forests versus monocultures: effects of tree size, stand density and season.

    Science.gov (United States)

    Forrester, David I

    2015-03-01

    Mixtures can be more productive than monocultures and may therefore use more water, which may make them more susceptible to droughts. The species interactions that influence growth, transpiration and water-use efficiency (WUE, tree growth per unit transpiration) within a given mixture vary with intra- and inter-annual climatic variability, stand density and tree size, but these effects remain poorly quantified. These relationships were examined in mixtures and monocultures of Eucalyptus globulus Labill. and Acacia mearnsii de Wildeman. Growth and transpiration were measured between ages 14 and 15 years. All E. globulus trees in mixture that were growing faster than similar sized trees in monocultures had higher WUE, while trees with similar growth rates had similar WUE. By the age of 14 years A. mearnsii trees were beginning to senesce and there were no longer any relationships between tree size and growth or WUE. The relationship between transpiration and tree size did not differ between treatments for either species, so stand-level increases in transpiration simply reflected the larger mean tree size in mixtures. Increasing neighbourhood basal area increased the complementarity effect on E. globulus growth and transpiration. The complementarity effect also varied throughout the year, but this was not related to the climatic seasonality. This study shows that stand-level responses can be the net effect of a much wider range of individual tree-level responses, but at both levels, if growth has not increased for a given species, it appears unlikely that there will be differences in transpiration or WUE for that species. Growth data may provide a useful initial indication of whether mixtures have higher transpiration or WUE, and which species and tree sizes contribute to this effect. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. 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.

  1. Transpiration directly regulates the emissions of water-soluble short-chained OVOCs.

    Science.gov (United States)

    Rissanen, K; Hölttä, T; Bäck, J

    2018-04-20

    Most plant-based emissions of volatile organic compounds (VOCs) are considered mainly temperature dependent. However, certain oxygenated VOCs (OVOCs) have high water solubility; thus, also stomatal conductance could regulate their emissions from shoots. Due to their water solubility and sources in stem and roots, it has also been suggested that their emissions could be affected by transport in xylem sap. Yet, further understanding on the role of transport has been lacking until present. We used shoot-scale long-term dynamic flux data from Scots pines (Pinus sylvestris) to analyse the effects of transpiration and transport in xylem sap flow on emissions of three water soluble OVOC: methanol, acetone and acetaldehyde. We found a direct effect of transpiration on the shoot emissions of the three OVOCs. The emissions were best explained by a regression model that combined linear transpiration and exponential temperature effects. In addition, a structural equation model indicated that stomatal conductance affects emissions mainly indirectly, by regulating transpiration. A part of temperature's effect is also indirect. The tight coupling of shoot emissions to transpiration clearly evidences that these OVOCs are transported in xylem sap from their sources in roots and stem to leaves and to ambient air. This article is protected by copyright. All rights reserved.

  2. Influence of water deficit on transpiration and radiation use efficiency of chickpea (Cicer arietinum L.)

    International Nuclear Information System (INIS)

    Singh, P.; Sri Rama, Y.V.

    1989-01-01

    Information on the relationship between biomass production, radiation use and water use of chickpea (Cicer arietinum L.) is essential to estimate biomass production in different water regimes. Experiments were conducted during three post-rainy seasons on a Vertisol (a typic pallustert) to study the effect of water deficits on radiation use, radiation use efficiency (RUE), transpiration and transpiration efficiency (TE) of chickpea. Different levels of soil water availability were created, either by having irrigated and non-irrigated plots or using a line source. Biomass production was linearly related to both cumulative intercepted solar radiation and transpiration in both well watered and water deficit treatments. Soil water availability did not affect RUE (total dry matter produced per unit of solar radiation interception) when at least 30% of extractable soil water (ESW) was present in the rooting zone, but below 30% ESW, RUE decreased linearly with the decrease in soil water content. RUE was also significantly correlated (R 2 = 0.61, P < 0.01) with the ratio of actual to potential transpiration (T/Tp) and it declined curvilinearly with the decrease in T/Tp. TE decreased with the increase in saturation deficit (SD) of air. Normalization of TE with SD gave a conservative value of 4.8 g kPa kg −1 . To estimate biomass production of chickpea in different environments, we need to account for the effect of plant water deficits on RUE in a radiation-based model and the effect of SD on TE in a transpiration-based model. (author)

  3. Reduced nighttime transpiration is a relevant breeding target for high water-use efficiency in grapevine.

    Science.gov (United States)

    Coupel-Ledru, Aude; Lebon, Eric; Christophe, Angélique; Gallo, Agustina; Gago, Pilar; Pantin, Florent; Doligez, Agnès; Simonneau, Thierry

    2016-08-09

    Increasing water scarcity challenges crop sustainability in many regions. As a consequence, the enhancement of transpiration efficiency (TE)-that is, the biomass produced per unit of water transpired-has become crucial in breeding programs. This could be achieved by reducing plant transpiration through a better closure of the stomatal pores at the leaf surface. However, this strategy generally also lowers growth, as stomatal opening is necessary for the capture of atmospheric CO2 that feeds daytime photosynthesis. Here, we considered the reduction in transpiration rate at night (En) as a possible strategy to limit water use without altering growth. For this purpose, we carried out a genetic analysis for En and TE in grapevine, a major crop in drought-prone areas. Using recently developed phenotyping facilities, potted plants of a cross between Syrah and Grenache cultivars were screened for 2 y under well-watered and moderate soil water deficit scenarios. High genetic variability was found for En under both scenarios and was primarily associated with residual diffusion through the stomata. Five quantitative trait loci (QTLs) were detected that underlay genetic variability in En Interestingly, four of them colocalized with QTLs for TE. Moreover, genotypes with favorable alleles on these common QTLs exhibited reduced En without altered growth. These results demonstrate the interest of breeding grapevine for lower water loss at night and pave the way to breeding other crops with this underexploited trait for higher TE.

  4. 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.

  5. 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...

  6. 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.

  7. Effect of different soil water potential on leaf transpiration and on stomatal conductance in poinsettia

    Directory of Open Access Journals (Sweden)

    Jacek S. Nowak

    2013-12-01

    Full Text Available Euphorbia pulcherrima Wild.'Lilo' was grown in containers in 60% peat, 30% perlite and 10% clay (v/v mixture, with different irrigation treatments based on soil water potential. Plants were watered at two levels of drought stress: -50kPa or wilting. The treatments were applied at different stages of plant development for a month or soil was brought to the moisture stress only twice. Additionally, some plants were watered at -50 kPa during the entire cultivation period while the control plants were watered at -5kPa. Plants were also kept at maximum possible moisture level (watering at -0,5kPa or close to it (-1.OkPa through the entire growing period. Soil water potential was measured with tensiometer. Drought stress applied during entire cultivation period or during the flushing stage caused significant reduction in transpiration and conductance of leaves. Stress applied during bract coloration stage had not as great effect on the stomatal conductance and transpiration of leaves as the similar stress applied during the flushing stage. High soil moisture increased stomatal conductance and transpiration rate, respectively by 130% and 52% (flushing stage, and 72% and 150% (bract coloration stage at maximum, compared to the control.

  8. Edge type affects leaf-level water relations and estimated transpiration of Eucalyptus arenacea.

    Science.gov (United States)

    Wright, Thomas E; Tausz, Michael; Kasel, Sabine; Volkova, Liubov; Merchant, Andrew; Bennett, Lauren T

    2012-03-01

    While edge effects on tree water relations are well described for closed forests, they remain under-examined in more open forest types. Similarly, there has been minimal evaluation of the effects of contrasting land uses on the water relations of open forest types in highly fragmented landscapes. We examined edge effects on the water relations and gas exchange of a dominant tree (Eucalyptus arenacea Marginson & Ladiges) in an open forest type (temperate woodland) of south-eastern Australia. Edge effects in replicate woodlands adjoined by cleared agricultural land (pasture edges) were compared with those adjoined by 7- to 9-year-old eucalypt plantation with a 25m fire break (plantation edges). Consistent with studies in closed forest types, edge effects were pronounced at pasture edges where photosynthesis, transpiration and stomatal conductance were greater for edge trees than interior trees (75m into woodlands), and were related to greater light availability and significantly higher branch water potentials at woodland edges than interiors. Nonetheless, gas exchange values were only ∼50% greater for edge than interior trees, compared with ∼200% previously found in closed forest types. In contrast to woodlands adjoined by pasture, gas exchange in winter was significantly lower for edge than interior trees in woodlands adjoined by plantations, consistent with shading and buffering effects of plantations on edge microclimate. Plantation edge effects were less pronounced in summer, although higher water use efficiency of edge than interior woodland trees indicated possible competition for water between plantation trees and woodland edge trees in the drier months (an effect that might have been more pronounced were there no firebreak between the two land uses). Scaling up of leaf-level water relations to stand transpiration using a Jarvis-type phenomenological model indicated similar differences between edge types. That is, transpiration was greater at pasture than

  9. Real-Time Determination of Photosynthesis, Transpiration, Water-Use Efficiency and Gene Expression of Two Sorghum bicolor (Moench Genotypes Subjected to Dry-Down

    Directory of Open Access Journals (Sweden)

    Alessandra Fracasso

    2017-05-01

    Full Text Available Plant growth and productivity are strongly affected by limited water availability in drought prone environments. The current climate change scenario, characterized by long periods without precipitations followed by short but intense rainfall, forces plants to implement different strategies to cope with drought stress. Understanding how plants use water during periods of limited water availability is of primary importance to identify and select the best adapted genotypes to a certain environment. Two sorghum genotypes IS22330 and IS20351, previously characterized as drought tolerant and drought sensitive genotypes, were subjected to progressive drought stress through a dry-down experiment. A whole-canopy multi-chamber system was used to determine the in vivo water use efficiency (WUE. This system records whole-canopy net photosynthetic and transpiration rate of 12 chambers five times per hour allowing the calculation of whole-canopy instantaneous WUE daily trends. Daily net photosynthesis and transpiration rates were coupled with gene expression dynamics of five drought related genes. Under drought stress, the tolerant genotype increased expression level for all the genes analyzed, whilst the opposite trend was highlighted by the drought sensitive genotype. Correlation between gene expression dynamics and gas exchange measurements allowed to identify three genes as valuable candidate to assess drought tolerance in sorghum.

  10. Real-Time Determination of Photosynthesis, Transpiration, Water-Use Efficiency and Gene Expression of Two Sorghum bicolor (Moench) Genotypes Subjected to Dry-Down.

    Science.gov (United States)

    Fracasso, Alessandra; Magnanini, Eugenio; Marocco, Adriano; Amaducci, Stefano

    2017-01-01

    Plant growth and productivity are strongly affected by limited water availability in drought prone environments. The current climate change scenario, characterized by long periods without precipitations followed by short but intense rainfall, forces plants to implement different strategies to cope with drought stress. Understanding how plants use water during periods of limited water availability is of primary importance to identify and select the best adapted genotypes to a certain environment. Two sorghum genotypes IS22330 and IS20351, previously characterized as drought tolerant and drought sensitive genotypes, were subjected to progressive drought stress through a dry-down experiment. A whole-canopy multi-chamber system was used to determine the in vivo water use efficiency (WUE). This system records whole-canopy net photosynthetic and transpiration rate of 12 chambers five times per hour allowing the calculation of whole-canopy instantaneous WUE daily trends. Daily net photosynthesis and transpiration rates were coupled with gene expression dynamics of five drought related genes. Under drought stress, the tolerant genotype increased expression level for all the genes analyzed, whilst the opposite trend was highlighted by the drought sensitive genotype. Correlation between gene expression dynamics and gas exchange measurements allowed to identify three genes as valuable candidate to assess drought tolerance in sorghum.

  11. Rates of nocturnal transpiration in two evergreen temperate woodland species with differing water-use strategies.

    Science.gov (United States)

    Zeppel, Melanie; Tissue, David; Taylor, Daniel; Macinnis-Ng, Catriona; Eamus, Derek

    2010-08-01

    Nocturnal fluxes may be a significant factor in the annual water budget of forested ecosystems. Here, we assessed sap flow in two co-occurring evergreen species (Eucalyptus parramattensis and Angophora bakeri) in a temperate woodland for 2 years in order to quantify the magnitude of seasonal nocturnal sap flow (E(n)) under different environmental conditions. The two species showed different diurnal water relations, demonstrated by different diurnal curves of stomatal conductance, sap flow and leaf water potential. The relative influence of several microclimatic variables, including wind speed (U), vapour pressure deficit (D), the product of U and D (UD) and soil moisture content, were quantified. D exerted the strongest influence on E(n) (r² = 0.59-0.86), soil moisture content influenced E(n) when D was constant, but U and UD did not generally influence E(n). In both species, cuticular conductance (G(c)) was a small proportion of total leaf conductance (G(s)) and was not a major pathway for E(n). We found that E(n) was primarily a function of transpiration from the canopy rather than refilling of stem storage, with canopy transpiration accounting for 50-70% of nocturnal flows. Mean E(n) was 6-8% of the 24-h flux across seasons (spring, summer and winter), but was up to 19% of the 24-h flux on some days in both species. Despite different daytime strategies in water use of the two species, both species demonstrated low night-time water loss, suggesting similar controls on water loss at night. In order to account for the impact of E(n) on pre-dawn leaf water potential arising from the influence of disequilibria between root zone and leaf water potential, we also developed a simple model to more accurately predict soil water potential (ψ(s)).

  12. 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.

  13. Destruction of an industrial wastewater by supercritical water oxidation in a transpiring wall reactor

    International Nuclear Information System (INIS)

    Bermejo, M.D.; Cocero, M.J.

    2006-01-01

    The supercritical water oxidation (SCWO) is a technology that takes advantage of the special properties of water in the surroundings of critical point of water to completely oxidize wastes in residence times lower than 1 min. The problems caused by the harsh operational conditions of the SCWO process are being solved by new reactor designs, such as the transpiring wall reactor (TWR). In this work, the operational parameters of a TWR have been studied for the treatment of an industrial wastewater. As a result, the process has been optimized for a feed flow of 16 kg/h with feed inlet temperatures higher than 300 deg. C and transpiring flow relation (R) between 0.2 and 0.6 working with an 8% (w/w) isopropanol (IPA) as a fuel. The experimental data and a mathematical model have been applied for the destruction of an industrial waste containing acetic acid and crotonaldehyde as main compounds. As the model predicted, removal efficiencies higher than 99.9% were obtained, resulting in effluents with 2 ppm total organic carbon (TOC) at feed flow of 16 kg/h, 320 deg. C of feed temperature and R = 0.32. An effluent TOC of 35 ppm under conditions feed flow of 18 kg/h, feed inlet temperatures of 290 deg. C, reaction temperatures of 570 deg. C and R = 0.6

  14. 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

    water potential (Wl), shoot and root abscisic acid concentration ([ABA]) and transpiration rate were measured in full irrigation (FI; around 95 % of water holding capacity (WHC)) and progressive drought (PD) treatments using the irrigation water with five salinity levels (0, 10, 20, 30 and 40 dS m)1...

  15. 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

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

    International Nuclear Information System (INIS)

    Isoda, A.; Wang, P.

    2001-01-01

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

  17. Development of synchronized, autonomous, and self-regulated oscillations in transpiration rate of a whole tomato plant under water stress.

    Science.gov (United States)

    Wallach, Rony; Da-Costa, Noam; Raviv, Michael; Moshelion, Menachem

    2010-07-01

    Plants respond to many environmental changes by rapidly adjusting their hydraulic conductivity and transpiration rate, thereby optimizing water-use efficiency and preventing damage due to low water potential. A multiple-load-cell apparatus, time-series analysis of the measured data, and residual low-pass filtering methods were used to monitor continuously and analyse transpiration of potted tomato plants (Solanum lycopersicum cv. Ailsa Craig) grown in a temperature-controlled greenhouse during well-irrigated and drought periods. A time derivative of the filtered residual time series yielded oscillatory behaviour of the whole plant's transpiration (WPT) rate. A subsequent cross-correlation analysis between the WPT oscillatory pattern and wet-wick evaporation rates (vertical cotton fabric, 0.14 m(2) partly submerged in water in a container placed on an adjacent load cell) revealed that autonomous oscillations in WPT rate develop under a continuous increase in water stress, whereas these oscillations correspond with the fluctuations in evaporation rate when water is fully available. The relative amplitude of these autonomous oscillations increased with water stress as transpiration rate decreased. These results support the recent finding that an increase in xylem tension triggers hydraulic signals that spread instantaneously via the plant vascular system and control leaf conductance. The regulatory role of synchronized oscillations in WPT rate in eliminating critical xylem tension points and preventing embolism is discussed.

  18. Transpirational water use and its regulation in the mountainous terrain of S. Korea

    Science.gov (United States)

    Otieno Dennis, O.; Eunyoung, J.; Sinkyu, K.; Tenhunen, J. D.

    2009-12-01

    Quantifying water use by forests growing on complex mountainous terrain is difficult and understanding of controls on water use by these forests a challenge. Yet mountains are crucial as water towers and better understanding of their hydrology and ecology is critical for sustainable management. Consequently, there is a growing need for new research approaches designed with attention to the particular needs and constraints of large-scale studies and that have the potential to generate reliable and accurate data. The use of a combination of different sapflow-measurement techniques provides a unique opportunity to monitor water use by the understory and canopy forest tree species at micro-scale, allowing for accurate estimation of total forest water use. The obtained data, in conjunction with intensively measured climatic variables, allow for better understanding and interpretation of transpiration results. A research initiative under the International Training Group: Complex Terrain and Ecological Heterogeneity (TERRECO) seeks to address pertinent issues related to forest water use and production in complex terrain. Stem Heat balance (SHB) and Heat Dissipation techniques have been employed to measure sapflow in the understory woody plants and tree branches and on stems of canopy trees respectively. Measurements have been stratified to account for differences in tree sizes and species diversity. To better understand the data, we are intensively monitoring soil moisture at 5, 10 and 30 cm depths, in addition to a range of micrometeorology sensors that have been set up below, within and above the canopy. These measurements have been planned, taking into account altitudinal/elevation gradient, aspect and within site differences in species composition and tree sizes and to generate data for large-scale modeling of the entire catchment. A total of 70 trees from 9 species growing in six different locations at varying elevations and aspects are being monitored. Peak daily

  19. 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...

  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. [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 transpiration rate also presented single-peak type, with the daily average value in late June and early August being (3.10 +/- 0.34) mmol H2O x m(-2) x s(-1) and (1.60 +/- 0.26) mmol H2O x m(-2) x s(-1), respectively, and differed significantly (P 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.

  2. Arbuscular Mycorrhiza Alleviates Restrictions to Substrate Water Flow and Delays Transpiration Limitation to Stronger Drought in Tomato.

    Science.gov (United States)

    Bitterlich, Michael; Sandmann, Martin; Graefe, Jan

    2018-01-01

    Arbuscular mycorrhizal fungi (AMF) proliferate in soil pores, on the surface of soil particles and affect soil structure. Although modifications in substrate moisture retention depend on structure and could influence plant water extraction, mycorrhizal impacts on water retention and hydraulic conductivity were rarely quantified. Hence, we asked whether inoculation with AMF affects substrate water retention, water transport properties and at which drought intensity those factors become limiting for plant transpiration. Solanum lycopersicum plants were set up in the glasshouse, inoculated or not with Funneliformis mosseae , and grown for 35 days under ample water supply. After mycorrhizal establishment, we harvested three sets of plants, one before (36 days after inoculation) and the second (day 42) and third (day 47) within a sequential drying episode. Sampling cores were introduced into pots before planting. After harvest, moisture retention and substrate conductivity properties were assessed and water retention and hydraulic conductivity models were fitted. A root water uptake model was adopted in order to identify the critical substrate moisture that induces soil derived transpiration limitation. Neither substrate porosity nor saturated water contents were affected by inoculation, but both declined after substrates dried. Drying also caused a decline in pot water capacity and hydraulic conductivity. Plant available water contents under wet (pF 1.8-4.2) and dry (pF 2.5-4.2) conditions increased in mycorrhizal substrates and were conserved after drying. Substrate hydraulic conductivity was higher in mycorrhizal pots before and during drought exposure. After withholding water from pots, higher substrate drying rates and lower substrate water potentials were found in mycorrhizal substrates. Mycorrhiza neither affected leaf area nor root weight or length. Consistently with higher substrate drying rates, AMF restored the plant hydraulic status, and increased plant

  3. 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.

  4. Increased transpiration and plant water stress in a black spruce bog exposed to whole ecosystem warming

    Science.gov (United States)

    Warren, J.; Ward, E. J.; Wullschleger, S. D.; Hanson, P. J.

    2017-12-01

    The Spruce and Peatland Responses under Changing Environments (SPRUCE) experiment (http://mnspruce.ornl.gov/) in Northern Minnesota, USA, has exposed 12.8 m diameter plots of an ombrotrophic Picea mariana-Ericaceous shrub bog to whole ecosystem warming (0, +2.25, +4.5, +6.75, +9 °C) since August 2015, and elevated CO2 treatments (ambient or +500 ppm) since June 2016. The mixed-age stand has trees up to 40 year old, and a 5-8 m tall canopy. Thermal dissipation sap flow probes were installed into dominant Picea mariana and Larix laricina trees in each of the 10 open-top chambers in fall 2015. This talk will focus on the first two years of sap flux data from the 10 treatment plots and the relationships with seasonal growth and prevailing environmental conditions. Sap flow was scaled to whole tree and plot level transpiration based on prior in situ calibrations using cut trees, establishment of a sapwood depth: tree diameter relationship, and the tree size distribution within each plot. We also assessed water potential in the trees and two dominant shrubs at the site: Rhododendron groenlandicum and Chamaedaphne calyculata. The warming treatments increased the growing season by up to 6 weeks, with sapflow beginning earlier in spring and lasting later into the fall. The deciduous Larix was the only species exhibiting substantial predawn water stress under the treatments, where water potentials reached -2.5 MPa for the warmest plots. The elevated CO2 reduced midday water stress in the Rhododendron, but not the Chamaedaphne, which could lead to shifts in shrub species composition.

  5. Modeling the water use efficiency of soybean and maize plants under environmental stresses: application of a synthetic model of photosynthesis-transpiration based on stomatal behavior.

    Science.gov (United States)

    Yu, Gui-Rui; Wang, Qiu-Feng; Zhuang, Jie

    2004-03-01

    Understanding the variability of plant WUE and its control mechanism can promote the comprehension to the coupling relationship of water and carbon cycle in terrestrial ecosystem, which is the foundation for developing water-carbon coupling cycle model. In this paper, we made clear the differences of net assimilation rate, transpiration rate, and WUE between the two species by comparing the experiment data of soybean (Glycine max Merr.) and maize (Zea mays L.) plants under water and soil nutrient stresses. WUE of maize was about two and a half times more than that of soybean in the same weather conditions. Enhancement of water stresses led to the marked decrease of Am and Em of two species, but water stresses of some degree could improve WUE, and this effect was more obvious for soybean. WUE of the two species changed with psiL in a second-order curve relation, and the WUE at high fertilization was higher than that at low fertilization, this effect was especially obvious for maize. Moreover, according to the synthetic model of photosynthesis-transpiration based on stomatal behavior (SMPTSB) presented by Yu et al. (2001), the WUE model and its applicability were discussed with the data measured in this experiment. The WUE estimated by means of the model accorded well with the measured values. However, this model underestimated the WUE for maize slightly, thus further improvement on the original model was made in this study. Finally, by discussing some physiological factors controlling Am and WUE, we made clear the physiological explanation for differences of the relative contributions of stomata- and mesophyll processes to control of Am and WUE, and the applicability of WUE model between the two species. Because the requirement to stomatal conductance by unit change of net assimilation rate is different, the responses of opening-closing activity of stomata to environmental stresses are different between the two species. To obtain the same level of net assimilation

  6. Effectiveness of cuticular transpiration barriers in a desert plant at controlling water loss at high temperatures.

    Science.gov (United States)

    Schuster, Ann-Christin; Burghardt, Markus; Alfarhan, Ahmed; Bueno, Amauri; Hedrich, Rainer; Leide, Jana; Thomas, Jacob; Riederer, Markus

    2016-01-01

    Maintaining the integrity of the cuticular transpiration barrier even at elevated temperatures is of vital importance especially for hot-desert plants. Currently, the temperature dependence of the leaf cuticular water permeability and its relationship with the chemistry of the cuticles are not known for a single desert plant. This study investigates whether (i) the cuticular permeability of a desert plant is lower than that of species from non-desert habitats, (ii) the temperature-dependent increase of permeability is less pronounced than in those species and (iii) whether the susceptibility of the cuticular permeability barrier to high temperatures is related to the amounts or properties of the cutin or the cuticular waxes. We test these questions with Rhazya stricta using the minimum leaf water vapour conductance (gmin) as a proxy for cuticular water permeability. gmin of R. stricta (5.41 × 10(-5) m s(-1) at 25 °C) is in the upper range of all existing data for woody species from various non-desert habitats. At the same time, in R. stricta, the effect of temperature (15-50 °C) on gmin (2.4-fold) is lower than in all other species (up to 12-fold). Rhazya stricta is also special since the temperature dependence of gmin does not become steeper above a certain transition temperature. For identifying the chemical and physical foundation of this phenomenon, the amounts and the compositions of cuticular waxes and cutin were determined. The leaf cuticular wax (251.4 μg cm(-2)) is mainly composed of pentacyclic triterpenoids (85.2% of total wax) while long-chain aliphatics contribute only 3.4%. In comparison with many other species, the triterpenoid-to-cutin ratio of R. stricta (0.63) is high. We propose that the triterpenoids deposited within the cutin matrix restrict the thermal expansion of the polymer and, thus, prevent thermal damage to the highly ordered aliphatic wax barrier even at high temperatures. Published by Oxford University Press on behalf of the

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

    Science.gov (United States)

    Ludwig, Fulco; Jewitt, Rebecca A; Donovan, Lisa A

    2006-06-01

    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 availability on night-time stomatal conductance (g) and transpiration (E). Water (low and high) and nutrients (low and high) were applied factorially during the growing season to naturally occurring seedlings of the annual Helianthus anomalus. Plant height and biomass were greatest in the treatment where both water and nutrients were added, confirming resource limitations in this habitat. Plants from all treatments showed significant night-time g (approximately 0.07 mol m(-2) s(-1)) and E (approximately 1.5 mol m(-2) s(-1)). In July, water and nutrient additions had few effects on day- or night-time gas exchange. In August, however, plants in the nutrient addition treatments had lower day-time photosynthesis, g and E, paralleled by lower night-time g and E. Lower predawn water potentials and higher integrated photosynthetic water-use efficiency suggests that the nutrient addition indirectly induced a mild water stress. Thus, soil resources can affect night-time g and E in a manner parallel to day-time, although additional factors may also be involved.

  8. 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...

  9. WaterNet: The NASA Water Cycle Solutions Network

    Science.gov (United States)

    Houser, P. R.; Belvedere, D. R.; Pozzi, W. H.; Imam, B.; Schiffer, R.; Lawford, R.; Schlosser, C. A.; Gupta, H.; Welty, C.; Vorosmarty, C.; Matthews, D.

    2007-12-01

    Water is essential to life and directly impacts and constrains society's welfare, progress, and sustainable growth, and is continuously being transformed by climate change, erosion, pollution, and engineering practices. The water cycle is a critical resource for industry, agriculture, natural ecosystems, fisheries, aquaculture, hydroelectric power, recreation, and water supply, and is central to drought, flood, transportation-aviation, and disease hazards. It is therefore a national priority to use advancements in scientific observations and knowledge to develop solutions to the water challenges faced by society. NASA's unique role is to use its view from space to improve water and energy cycle monitoring and prediction. NASA has collected substantial water cycle information and knowledge that must be transitioned to develop solutions for all twelve National Priority Application (NPA) areas. NASA cannot achieve this goal alone -it must establish collaborations and interoperability with existing networks and nodes of research organizations, operational agencies, science communities, and private industry. Therefore, WaterNet: The NASA Water Cycle Solutions Network goal is to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend NASA research results to augment decision support tools and meet national needs. WaterNet is a catalyst for discovery and sharing of creative solutions to water problems. It serves as a creative, discovery process that is the entry-path for a research-to-solutions systems engineering NASA framework, with the end result to ultimately improve decision support.

  10. 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

  11. Modeling of water treatment plant using timed continuous Petri nets

    Science.gov (United States)

    Nurul Fuady Adhalia, H.; Subiono, Adzkiya, Dieky

    2017-08-01

    Petri nets represent graphically certain conditions and rules. In this paper, we construct a model of the Water Treatment Plant (WTP) using timed continuous Petri nets. Specifically, we consider that (1) the water pump always active and (2) the water source is always available. After obtaining the model, the flow through the transitions and token conservation laws are calculated.

  12. 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

  13. The effect of water availability on stand-level productivity, transpiration, water use efficiency and radiation use efficiency of field-grown willow clones

    International Nuclear Information System (INIS)

    Linderson, Maj-Lena; Iritz, Zinaida; Lindroth, Anders

    2007-01-01

    The effect of water availability on stand-level productivity, transpiration, water use efficiency (WUE) and radiation use efficiency (RUE) is evaluated for different willow clones at stand level. The measurements were made during the growing season 2000 in a 3-year-old plantation in Scania, southernmost Sweden. Six willow clones were included in the study: L78183, SW Rapp, SW Jorunn, SW Jorr, SW Tora and SW Loden. All clones were exposed to two water treatments: rain-fed, non-irrigated treatment and reduced water availability by reduced soil water recharge. Field measurements of stem sap-flow and biometry are up-scaled to stand transpiration and stand dry substance production and used to assess WUE. RUE is estimated from the ratio between the stand dry substance production and the accumulated absorbed photosynthetic active radiation over the growing season. The total stand transpiration rate for the 5 months lies between 100 and 325 mm, which is fairly low compared to the Penman-Monteith transpiration for willow, reaching 400-450 mm for the same period. Mean WUE of all clones and treatments is 5.3 g/kg, which is high compared to earlier studies, while average RUE is 0.31 g/mol, which is slightly low compared to other results. Generally, all clones, except for Jorunn, seem to be better off concerning biomass production, WUE and RUE than the reference clone. Jorr, Jorunn and Loden also seem to be able to cope with the reduced water availability with increase in the water use efficiency. Tora performs significantly better than the other clones concerning both growth and efficiency in light and water use, but the effect of the dry treatment on stem growth shows sensitivity to water availability. The reduced stem growth could be due to a change in allocation patterns

  14. Water consumption in artificial desert oasis based on net primary productivity

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Analysis of the water consumption is the basis for water allocation in oasis. However, the method of estimating oasis water consumption remains a great challenge. Based on net primary productivity (NPP) and the transpiration coefficient, a vegetation water consumption model was developed to estimate the water consumption in desert oasis in ERDAS environment. Our results demonstrated that the ecosystem in the middle reaches of the Heihe oasis consumed water of 18.41×108-21.9×108 m3 for irrigation. Without taking precipitation into account, the water consumption in farmland accounted for 77.1%-77.8% (or about 13.97×108-16.84×108 m3) of the oasis vegetation water consumption and in the farmland protection system accounting for 22%. The growing period precipitation in desert environments is about 7.02×108 m3, and the total annual precipitation is about 8.29×108 m3. The modeled water consumption of desert vegetation, however, is about 4.57×108 m3, equivalent to only 65% of the growing period precipitation or 55% of the total annual precipitation. The modeled value equals to the cumulative precipitation of greater than 5 mm, which is defined as the effective precipitation in arid desert.

  15. Do Reductions in Dry Season Transpiration Allow Shallow Soil Water Uptake to Persist in a Tropical Lower Montane Cloud Forest?

    Science.gov (United States)

    Munoz Villers, L. E.; Holwerda, F.; Alvarado-Barrientos, M. S.; Goldsmith, G. R.; Geissert Kientz, D. R.; González Martínez, T. M.; Dawson, T. E.

    2016-12-01

    Tropical montane cloud forests (TMCF) are ecosystems particularly sensitive to climate change; however, the effects of warmer and drier conditions on TMCF water cycling remain poorly understood. To investigate the plant functional response to reduced water availability, we conducted a study during the mid to late dry season (2014) in the lower limit (1,325 m asl) of the TMCF belt (1200-2500 m asl) in central Veracruz, Mexico. The temporal variation of transpiration rates of dominant upper canopy and mid-story tree species, depth of water uptake, as well as tree water sources were examined using micrometeorological, sapflow and soil moisture measurements, in combination with data on stable isotope (δ18O and δ2H) composition of rain, tree xylem, soil (bulk and low suction-lysimeter) and stream water. The sapflow data suggest that crown conductances decreased as temperature and vapor pressure deficit increased, and soil moisture decreased from the mid to late dry season. Across all samplings (January 21, April 12 and 26), upper canopy species (Quercus spp.) showed more depleted (negative) isotope values compared to mid-story trees (Carpinus tropicalis). Overall, we found that the evaporated soil water pool was the main source for the trees. Furthermore, our MixSIAR Bayesian mixing model results showed that the depth of tree water uptake changed over the course of the dry season. Unexpectedly, a shift in water uptake from deeper (60-120 cm depth) to shallower soil water (0-30 cm) sources was observed, coinciding with the decreases in transpiration rates towards the end of the dry season. A larger reduction in deep soil water contributions was observed for upper canopy trees (from 70±14 to 22±15%) than for mid-story species (from 10±13 to 7±10%). The use of shallow soil water by trees during the dry season seems consistent with the greater root biomass and higher macronutrient concentrations found in the first 10 cm of the soil profiles. These findings are an

  16. Stress-inducible expression of At DREB1A in transgenic peanut (Arachis hypogaea L.) increases transpiration efficiency under water-limiting conditions.

    Science.gov (United States)

    Bhatnagar-Mathur, Pooja; Devi, M Jyostna; Reddy, D Srinivas; Lavanya, M; Vadez, Vincent; Serraj, R; Yamaguchi-Shinozaki, K; Sharma, Kiran K

    2007-12-01

    Water deficit is the major abiotic constraint affecting crop productivity in peanut (Arachis hypogaea L.). Water use efficiency under drought conditions is thought to be one of the most promising traits to improve and stabilize crop yields under intermittent water deficit. A transcription factor DREB1A from Arabidopsis thaliana, driven by the stress inducible promoter from the rd29A gene, was introduced in a drought-sensitive peanut cultivar JL 24 through Agrobacterium tumefaciens-mediated gene transfer. The stress inducible expression of DREB1A in these transgenic plants did not result in growth retardation or visible phenotypic alterations. T3 progeny of fourteen transgenic events were exposed to progressive soil drying in pot culture. The soil moisture threshold where their transpiration rate begins to decline relative to control well-watered (WW) plants and the number of days needed to deplete the soil water was used to rank the genotypes using the average linkage cluster analysis. Five diverse events were selected from the different clusters and further tested. All the selected transgenic events were able to maintain a transpiration rate equivalent to the WW control in soils dry enough to reduce transpiration rate in wild type JL 24. All transgenic events except one achieved higher transpiration efficiency (TE) under WW conditions and this appeared to be explained by a lower stomatal conductance. Under water limiting conditions, one of the selected transgenic events showed 40% higher TE than the untransformed control.

  17. Effect of near-infrared-radiation reflective screen materials on ventilation requirement, crop transpiration and water use efficiency of a greenhouse rose crop

    NARCIS (Netherlands)

    Stanghellini, C.; Jianfeng, D.; Kempkes, F.L.K.

    2011-01-01

    The effect of Near Infrared (NIR)-reflective screen material on ventilation requirement, crop transpiration and water use efficiency of a greenhouse rose crop was investigated in an experiment whereby identical climate was ensured in greenhouse compartments installed with either NIR-reflective or

  18. The effect of water availability on stand-level productivity, transpiration, water use efficiency and radiation use efficiency of field-grown willow clones

    DEFF Research Database (Denmark)

    Linderson, Maj-Lena; Iritz, Z.; Lindroth, A.

    2007-01-01

    The effect of water availability on stand-level productivity, transpiration, water use efficiency (WUE) and radiation use efficiency (RUE) is evaluated for different willow clones at stand level. The measurements were made during the growing season 2000 in a 3-year-old plantation in Scania......, southernmost Sweden. Six willow clones were included in the study: L78183, SW Rapp, SW Jorunn, SW Jorr, SW Tora and SW Loden. All clones were exposed to two water treatments: rain-fed, non-irrigated treatment and reduced water availability by reduced soil water recharge. Field measurements of stem sap...... low compared to other results. Generally, all clones, except for Jorunn, seem to be better off concerning biomass production, WUE and RUE than the reference clone. Jorr, Jorunn and Loden also seem to be able to cope with the reduced water availability with increase in the water use efficiency. Tora...

  19. 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

  20. Response of the physiological parameters of mango fruit (transpiration, water relations and antioxidant system) to its light and temperature environment.

    Science.gov (United States)

    Léchaudel, Mathieu; Lopez-Lauri, Félicie; Vidal, Véronique; Sallanon, Huguette; Joas, Jacques

    2013-04-15

    Depending on the position of the fruit in the tree, mango fruit may be exposed to high temperature and intense light conditions that may lead to metabolic and physiological disorders and affect yield and quality. The present study aimed to determine how mango fruit adapted its functioning in terms of fruit water relations, epicarp characteristics and the antioxidant defence system in peel, to environmental conditions. The effect of contrasted temperature and light conditions was evaluated under natural solar radiation and temperature by comparing well-exposed and shaded fruit at three stages of fruit development. The sun-exposed and shaded peels of the two sides of the well-exposed fruit were also compared. Depending on fruit position within the canopy and on the side of a well-exposed fruit, the temperature gradient over a day affected fruit characteristics such as transpiration, as revealed by the water potential gradient as a function of the treatments, and led to a significant decrease in water conductance for well-exposed fruits compared to fruits within the canopy. Changes in cuticle thickness according to fruit position were consistent with those of fruit water conductance. Osmotic potential was also affected by climatic environment and harvest stage. Environmental conditions that induced water stress and greater light exposure, like on the sunny side of well-exposed fruit, increased the hydrogen peroxide, malondialdehyde and total and reduced ascorbate contents, as well as SOD, APX and MDHAR activities, regardless of the maturity stage. The lowest values were measured in the peel of the shaded fruit, that of the shaded side of well-exposed fruit being intermediate. Mango fruits exposed to water-stress-induced conditions during growth adapt their functioning by reducing their transpiration. Moreover, oxidative stress was limited as a consequence of the increase in antioxidant content and enzyme activities. This adaptive response of mango fruit to its

  1. 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 ...

  2. Genetic Variation of Morphological Traits and Transpiration in an Apple Core Collection under Well-Watered Conditions: Towards the Identification of Morphotypes with High Water Use Efficiency.

    Directory of Open Access Journals (Sweden)

    Gerardo Lopez

    Full Text Available Water use efficiency (WUE is a quantitative measurement which improvement is a major issue in the context of global warming and restrictions in water availability for agriculture. In this study, we aimed at studying the variation and genetic control of WUE and the respective role of its components (plant biomass and transpiration in a perennial fruit crop. We explored an INRA apple core collection grown in a phenotyping platform to screen one-year-old scions for their accumulated biomass, transpiration and WUE under optimal growing conditions. Plant biomass was decompose into morphological components related to either growth or organ expansion. For each trait, nine mixed models were evaluated to account for the genetic effect and spatial heterogeneity inside the platform. The Best Linear Unbiased Predictors of genetic values were estimated after model selection. Mean broad-sense heritabilities were calculated from variance estimates. Heritability values indicated that biomass (0.76 and WUE (0.73 were under genetic control. This genetic control was lower in plant transpiration with an heritability of 0.54. Across the collection, biomass accounted for 70% of the WUE variability. A Hierarchical Ascendant Classification of the core collection indicated the existence of six groups of genotypes with contrasting morphology and WUE. Differences between morphotypes were interpreted as resulting from differences in the main processes responsible for plant growth: cell division leading to the generation of new organs and cell elongation leading to organ dimension. Although further studies will be necessary on mature trees with more complex architecture and multiple sinks such as fruits, this study is a first step for improving apple plant material for the use of water.

  3. Genetic Variation of Morphological Traits and Transpiration in an Apple Core Collection under Well-Watered Conditions: Towards the Identification of Morphotypes with High Water Use Efficiency.

    Science.gov (United States)

    Lopez, Gerardo; Pallas, Benoît; Martinez, Sébastien; Lauri, Pierre-Éric; Regnard, Jean-Luc; Durel, Charles-Éric; Costes, Evelyne

    2015-01-01

    Water use efficiency (WUE) is a quantitative measurement which improvement is a major issue in the context of global warming and restrictions in water availability for agriculture. In this study, we aimed at studying the variation and genetic control of WUE and the respective role of its components (plant biomass and transpiration) in a perennial fruit crop. We explored an INRA apple core collection grown in a phenotyping platform to screen one-year-old scions for their accumulated biomass, transpiration and WUE under optimal growing conditions. Plant biomass was decompose into morphological components related to either growth or organ expansion. For each trait, nine mixed models were evaluated to account for the genetic effect and spatial heterogeneity inside the platform. The Best Linear Unbiased Predictors of genetic values were estimated after model selection. Mean broad-sense heritabilities were calculated from variance estimates. Heritability values indicated that biomass (0.76) and WUE (0.73) were under genetic control. This genetic control was lower in plant transpiration with an heritability of 0.54. Across the collection, biomass accounted for 70% of the WUE variability. A Hierarchical Ascendant Classification of the core collection indicated the existence of six groups of genotypes with contrasting morphology and WUE. Differences between morphotypes were interpreted as resulting from differences in the main processes responsible for plant growth: cell division leading to the generation of new organs and cell elongation leading to organ dimension. Although further studies will be necessary on mature trees with more complex architecture and multiple sinks such as fruits, this study is a first step for improving apple plant material for the use of water.

  4. Effect of Leaf Water Potential on Internal Humidity and CO2 Dissolution: Reverse Transpiration and Improved Water Use Efficiency under Negative Pressure.

    Science.gov (United States)

    Vesala, Timo; Sevanto, Sanna; Grönholm, Tiia; Salmon, Yann; Nikinmaa, Eero; Hari, Pertti; Hölttä, Teemu

    2017-01-01

    The pull of water from the soil to the leaves causes water in the transpiration stream to be under negative pressure decreasing the water potential below zero. The osmotic concentration also contributes to the decrease in leaf water potential but with much lesser extent. Thus, the surface tension force is approximately balanced by a force induced by negative water potential resulting in concavely curved water-air interfaces in leaves. The lowered water potential causes a reduction in the equilibrium water vapor pressure in internal (sub-stomatal/intercellular) cavities in relation to that over water with the potential of zero, i.e., over the flat surface. The curved surface causes a reduction also in the equilibrium vapor pressure of dissolved CO 2 , thus enhancing its physical solubility to water. Although the water vapor reduction is acknowledged by plant physiologists its consequences for water vapor exchange at low water potential values have received very little attention. Consequences of the enhanced CO 2 solubility to a leaf water-carbon budget have not been considered at all before this study. We use theoretical calculations and modeling to show how the reduction in the vapor pressures affects transpiration and carbon assimilation rates. Our results indicate that the reduction in vapor pressures of water and CO 2 could enhance plant water use efficiency up to about 10% at a leaf water potential of -2 MPa, and much more when water potential decreases further. The low water potential allows for a direct stomatal water vapor uptake from the ambient air even at sub-100% relative humidity values. This alone could explain the observed rates of foliar water uptake by e.g., the coastal redwood in the fog belt region of coastal California provided the stomata are sufficiently open. The omission of the reduction in the water vapor pressure causes a bias in the estimates of the stomatal conductance and leaf internal CO 2 concentration based on leaf gas exchange

  5. 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

  6. How soil water storage moderates climate changes effects on transpiration, across the different climates of the Critical Zone Observatories

    Science.gov (United States)

    Heckman, C.; Tague, C.

    2017-12-01

    While the demand side of transpiration is predicted to increase under a warmer climate, actual evapotranspiration (AET) will be moderated by the supply of water available to vegetation. A key question to ask is how will plant accessible water storage capacity (PAWSC) affect the partitioning of precipitation between AET and runoff. Our results indicate that whether AET increases or decreases, and how much, is significantly based upon interactions between PAWSC and characteristics of precipitation such as the amount, frequency, and skew as well the partitioning between rain and snow. In snow dominated climates, if PAWSC cannot make up for the loss of storage as snowpack then AET could decrease, and in rain dominated climates, PAWSC could significantly limit the increase in AET. These results highlight the importance of critical zone research: constraining PAWSC is critical in predicting not only the magnitude but also the direction of the change in AET with climate warming. Due to the highly heterogeneous nature of PAWSC and the difficulty of measuring it across large scales, we use a well-tested hydrologic model to estimate the impacts from a range of PAWSC on the partitioning of precipitation between runoff and AET. We completed this analysis for the range of precipitation and vegetation characteristics found across 9 of the Critical Zone Observatories.

  7. Tuberous Roots Yield, Transpiration Rate, Stomatal Conductance and Water Use Efficiency of Divergent Cassava Clones as Influenced by Climate and Growth Stage

    International Nuclear Information System (INIS)

    Githunguri, C.M; Chewa, J.A; Ekanayake, I.J

    1999-01-01

    Cassava roots provide a cheap source of dietary energy to millions of people in the tropics. Variations in yield, stomatal conductance, transpiration rate and water use efficiency occur due to various factors. This makes selection of clones with wide ecological adaptation and high yield difficult. The influence of crop age and agroecozones (AEZ) in Nigeria on above parametres were studied. The tested AEZs were Sudan savanna (Minjibir), Southern Guinea savanna (Mokwa) and forest-savanna transition (Ibadan) AEZ. The environment plays a significant role in determining root yield with plant age playing a bigger role at the early stages. Results suggest root development was restricted by low moisture stress. Cassava ought to be harvested at eight months after planting (MAP) rather than at 12 MAP in order to obtain maximum yields. Yields at Mokwa were significantly higher than both Minjibir and Ibadan suggesting that cassava is not a crop for either forest or semi arid zones. During both seasons Minjbir had the highest stomatal conductance trend while Ibadan had the lowest. Stomatal conductance at Minjibir becomes critical at 12 MAP. The highest transpiration rate was recorded at Minijibir at 4 and 12 MAP. The lowest transpiration rate ws observed at Ibadan. The lowest transpiration rate was also observed during drought. There was a close positive close relationship between tuberous roots yield and transpiration. The lowest and highest water use efficiency (WUE) was recorded at 4 and 8 MAP during rains. The lowest and the highest WUE was recorded at Ibadan and Mokwa respectively. The two seasons trends were similar. Clone TMS 50395 had the highest WUE. Tere was close positive relationship between WUE and tuberous roots yield

  8. Soil water storage, yield, water productivity and transpiration efficiency of soybeans (Glyxine max L.Merr as affected by soil surface management in Ile-Ife, Nigeria

    Directory of Open Access Journals (Sweden)

    Omotayo B. Adeboye

    2017-06-01

    Full Text Available Rainfed agriculture has a high yield potential if rainfall and land resources are effectively used. In this study, conventional (NC and six in-situ water conservation practices were used to cultivate Soybean in 2011 and 2012 in Ile-Ife, Nigeria. The conservation practices are: Tied ridge (TR, Soil bund (BD, Mulch (ML, Mulch plus Soil bund (MLBD, Tied ridge plus Mulch (TRML, Tied ridge plus Soil bund (TRBD. The practices were arranged in Randomised Complete Block Design with four replicates. Seasonal rainfall was 539 and 761 mm in 2011 and 2012, respectively. Seasonal soil water storage (SWS ranged from 485 mm for NC to 517 mm for TRML in the two seasons. ML increased the SWS in the upper 30 cm of the soil by 17% while TR increased the soil water content in the lower 30–60 cm by 22% compared with NC. ML reduced soil temperature in the upper 30 cm between 2.2 and 2.9 oC compared with NC, TR and TRML. Seasonal crop evapotranspiration ranged between 432 mm for NC and 481 mm for BD in the seasons. Grain yield increased by 41.7% and 44.3% for BD and MLBD, respectively compared with NC. Water conservation practices increased water productivity for grain yield by 14.0–41.8% compared with NC. Similarly, it increased average seasonal transpiration efficiency by 15.3–32.5% compared with NC. These findings demonstrate that when there are fluctuations in rainfall, in-situ water conservation practices improve SWS, land, and water productivity and transpiration efficiency of Soybeans.

  9. Interactive effects of nocturnal transpiration and climate change on the root hydraulic redistribution and carbon and water budgets of southern United States pine plantations.

    Science.gov (United States)

    Domec, Jean-Christophe; Ogée, Jérôme; Noormets, Asko; Jouangy, Julien; Gavazzi, Michael; Treasure, Emrys; Sun, Ge; McNulty, Steve G; King, John S

    2012-06-01

    Deep root water uptake and hydraulic redistribution (HR) have been shown to play a major role in forest ecosystems during drought, but little is known about the impact of climate change, fertilization and soil characteristics on HR and its consequences on water and carbon fluxes. Using data from three mid-rotation loblolly pine plantations, and simulations with the process-based model MuSICA, this study indicated that HR can mitigate the effects of soil drying and had important implications for carbon uptake potential and net ecosystem exchange (NEE), especially when N fertilization is considered. At the coastal site (C), characterized by deep organic soil, HR increased dry season tree transpiration (T) by up to 40%, and such an increase affected NEE through major changes in gross primary productivity (GPP). Deep-rooted trees did not necessarily translate into a large volume of HR unless soil texture allowed large water potential gradients to occur, as was the case at the sandy site (S). At the Piedmont site (P) characterized by a shallow clay-loam soil, HR was low but not negligible, representing up to 10% of T. In the absence of HR, it was predicted that at the C, S and P sites, annual GPP would have been diminished by 19, 7 and 9%, respectively. Under future climate conditions HR was predicted to be reduced by up to 25% at the C site, reducing the resilience of trees to precipitation deficits. The effect of HR on T and GPP was predicted to diminish under future conditions by 12 and 6% at the C and P sites, respectively. Under future conditions, T was predicted to stay the same at the P site, but to be marginally reduced at the C site and slightly increased at the S site. Future conditions and N fertilization would decrease T by 25% at the C site, by 15% at the P site and by 8% at the S site. At the C and S sites, GPP was estimated to increase by 18% and by >70% under future conditions, respectively, with little effect of N fertilization. At the P site, future

  10. On the spatial distribution of the transpiration and soil moisture of a Mediterranean heterogeneous ecosystem in water-limited conditions.

    Science.gov (United States)

    Curreli, Matteo; Corona, Roberto; Montaldo, Nicola; Albertson, John D.; Oren, Ram

    2014-05-01

    Mediterranean ecosystems are characterized by a strong heterogeneity, and often by water-limited conditions. In these conditions contrasting plant functional types (PFT, e.g. grass and woody vegetation) compete for the water use. Both the vegetation cover spatial distribution and the soil properties impact the soil moisture (SM) spatial distribution. Indeed, vegetation cover density and type affects evapotranspiration (ET), which is the main lack of the soil water balance in these ecosystems. With the objective to carefully estimate SM and ET spatial distribution in a Mediterranean water-limited ecosystem and understanding SM and ET relationships, an extended field campaign is carried out. The study was performed in a heterogeneous ecosystem in Orroli, Sardinia (Italy). The experimental site is a typical Mediterranean ecosystem where the vegetation is distributed in patches of woody vegetation (wild olives mainly) and grass. Soil depth is low and spatially varies between 10 cm and 40 cm, without any correlation with the vegetation spatial distribution. ET, land-surface fluxes and CO2 fluxes are estimated by an eddy covariance technique based micrometeorological tower. But in heterogeneous ecosystems a key assumption of the eddy covariance theory, the homogeneity of the surface, is not preserved and the ET estimate may be not correct. Hence, we estimate ET of the woody vegetation using the thermal dissipation method (i.e. sap flow technique) for comparing the two methodologies. Due the high heterogeneity of the vegetation and soil properties of the field a total of 54 sap flux sensors were installed. 14 clumps of wild olives within the eddy covariance footprint were identified as the most representative source of flux and they were instrumented with the thermal dissipation probes. Measurements of diameter at the height of sensor installation (height of 0.4 m above ground) were recorded in all the clumps. Bark thickness and sapwood depth were measured on several

  11. Microclimate, Water Potential, Transpiration, and Bole Dielectric Constant of Coniferous and Deciduous Tree Species in the Continental Boreal Ecotone of Central Alaska

    Science.gov (United States)

    Zimmermann, R.; McDonald, K.; Way, J.; Oren, R.

    1994-01-01

    Tree canopy microclimate, xylem water flux and xylem dielectric constant have been monitored in situ since June 1993 in two adjacent natural forest stands in central Alaska. The deciduous stand represents a mature balsam poplar site on the Tanana River floodplain, while the coniferous stand consists of mature white spruce with some black spruce mixed in. During solstice in June and later in summer, diurnal changes of xylem water potential were measured to investigate the occurrence and magnitude of tree transpiration and dielectric constant changes in stems.

  12. A phytotoxicity test using transpiration of willows

    DEFF Research Database (Denmark)

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

    2000-01-01

    is expressed as % decrease after 48 and 72 h or longer compared to the initial transpiration, divided by the transpiration of control plants. More toxicity parameters are growth and water use efficiency of the plants. The sensitivity of the test was evaluated with 3,5-dichlorophenol. EC50 values between 5......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....... Transpiration is closely related to photosynthesis and growth, but is easier and faster to measure and can be measured without disturbance of the test system. Plants are grown for 24 h in uncontaminated nutrient solution before the toxicant is added to determine the initial transpiration. The loss of weight...

  13. Water Sustainability Assessments for Four Net Zero Water Installations

    Science.gov (United States)

    2013-12-01

    average daily water use, in six leaks. While the cost of the lost water might seem insignificant using current valuation methods, the financial impacts...One function of GFEBS is to identify facility maintenance requirements through integrated asset valuation and depreciation. The desired outcome is...considers tapping groundwater reservoirs as an additional water source. The most feasible groundwater source would likely originate in an alluvial valley

  14. Transpiration efficiency and its relationship with carbon isotope discrimination under well-watered and water-stressed conditions in Stylosanthes scabra

    International Nuclear Information System (INIS)

    Thumma, B.R.; Naidu, B.P.; Cameron, D. F.; Bahnisch, L. M.

    1998-01-01

    Stylosanthes scabra cv. Seca is a widely sown tropical pasture legume in northern Australia and has a high degree of drought resistance. Identification of traits contributing to the drought resistance of Seca may be valuable for use in breeding programs. Transpiration efficiency (TE) has been suggested as one such trait contributing to drought resistance. Carbon isotope discrimination (Δ) has been proposed for estimating TE indirectly in C 3 plants. A glasshouse experiment was conducted using 8 accessions of S. scabra to identify whether Seca differs in TE from other accessions of S. scabra and to determine the relationship between TE and Δ) under both well-watered and water-stressed treatments. Seca maintained the highest TE (lowest Δ) under both control and stress treatments, and leaf Δ was significantly and negatively correlated with TE under both control and stress conditions. A significant and negative relationship was found between Δ and dry matter production under stress treatment. The interaction between accession and watering treatment was not significant for either TE or Δ. We also found a significant agreement between the performance in the field and in the laboratory for these 8 accessions. These results indicate that TE could be one of the significant factors contributing to drought resistance of Seca. Furthermore, Δ and/or specific leaf area may be useful as selection criteria in breeding programs to identify the lines with high TE. Copyright (1998) CSIRO Australia

  15. Experimental study on the operating characteristics of an inner preheating transpiring wall reactor for supercritical water oxidation: Temperature profiles and product properties

    International Nuclear Information System (INIS)

    Zhang, Fengming; Xu, Chunyan; Zhang, Yong; Chen, Shouyan; Chen, Guifang; Ma, Chunyuan

    2014-01-01

    A new process to generate multiple thermal fluids by supercritical water oxidation (SCWO) was proposed to enhance oil recovery. An inner preheating transpiring wall reactor for SCWO was designed and tested to avoid plugging in the preheating section. Hot water (400–600 °C) was used as auxiliary heat source to preheat the feed to the reaction temperature. The effect of different operating parameters on the performance of the inner preheating transpiring wall reactor was investigated, and the optimized operating parameters were determined based on temperature profiles and product properties. The reaction temperature is close to 900 °C at an auxiliary heat source flow of 2.79 kg/h, and the auxiliary heat source flow is determined at 6–14 kg/h to avoid the overheating of the reactor. The useful reaction time is used to quantitatively describe the feed degradation efficiency. The outlet concentration of total organic carbon (TOC out ) and CO in the effluent gradually decreases with increasing useful reaction time. The useful reaction time needed for complete oxidation of the feed is 10.5 s for the reactor. - Highlights: • A new process to generate multiple thermal fluids by SCWO was proposed. • An inner preheating transpiring wall reactor for SCWO was designed and tested. • Hot water was used as auxiliary heat source to preheat the feed at room temperature. • Effect of operating parameters on the performance of the reactor was investigated. • The useful reaction time required for complete oxidation of the feed is 10.5 s

  16. Community level offset of rain use- and transpiration efficiency for a heavily grazed ecosystem in inner Mongolia grassland.

    Science.gov (United States)

    Gao, Ying Z; Giese, Marcus; Gao, Qiang; Brueck, Holger; Sheng, Lian X; Yang, Hai J

    2013-01-01

    Water use efficiency (WUE) is a key indicator to assess ecosystem adaptation to water stress. Rain use efficiency (RUE) is usually used as a proxy for WUE due to lack of transpiration data. Furthermore, RUE based on aboveground primary productivity (RUEANPP) is used to evaluate whole plant water use because root production data is often missing as well. However, it is controversial as to whether RUE is a reliable parameter to elucidate transpiration efficiency (TE), and whether RUEANPP is a suitable proxy for RUE of the whole plant basis. The experiment was conducted at three differently managed sites in the Inner Mongolia steppe: a site fenced since 1979 (UG79), a winter grazing site (WG) and a heavily grazed site (HG). Site HG had consistent lowest RUEANPP and RUE based on total net primary productivity (RUENPP). RUEANPP is a relatively good proxy at sites UG79 and WG, but less reliable for site HG. Similarly, RUEANPP is good predictor of transpiration efficiency based on aboveground net primary productivity (TEANPP) at sites UG79 and WG but not for site HG. However, if total net primary productivity is considered, RUENPP is good predictor of transpiration efficiency based on total net primary productivity (TENPP) for all sites. Although our measurements indicate decreased plant transpiration and consequentially decreasing RUE under heavy grazing, productivity was relatively compensated for with a higher TE. This offset between RUE and TE was even enhanced under water limited conditions and more evident when belowground net primary productivity (BNNP) was included. These findings suggest that BNPP should be considered when studies fucus on WUE of more intensively used grasslands. The consideration of the whole plant perspective and "real" WUE would partially revise our picture of system performance and therefore might affect the discussion on the C-sequestration and resilience potential of ecosystems.

  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. WaterNet: The NASA water cycle solutions network - Danubian regional applications

    International Nuclear Information System (INIS)

    Matthews, Dave; Brilly, Mitja; Kobold, Mira; Zagar, Mark; Houser, Paul

    2008-01-01

    WaterNet is a new international network of researchers, stakeholders, and end-users of remote sensing tools that will benefit the water resources management community. This paper provides an overview and it discusses the concept of solutions networks focusing on the WaterNet. It invites Danubian research and applications teams to join our WaterNet network. The NASA Water cycle Solutions Network's goal is to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend NASA research results to augment decision support tools and meet national needs. Our team will develop WaterNet by engaging relevant NASA water cycle research resources and community-of-practice organizations, to develop what we term an 'actionable database' that can be used to communicate and connect NASA Water cycle research Results (NWRs) towards the improvement of water-related Decision Support Tools (DSTs). Recognizing that the European Commission and European Space Agency have also developed many related Water Research products (EWRs), we seek to learn about these and network with the EU teams to include their information in the WaterNet actionable data base and Community of Practice. WaterNet will then develop strategies to connect researchers and decision-makers via innovative communication strategies, improved user access to NASA and EU - Danubian resources, improved water cycle research community appreciation for user requirements, improved policymaker, management and stakeholder knowledge of research and application products, and improved identification of pathways for progress. Finally, WaterNet will develop relevant benchmarking and metrics, to understand the network's characteristics, to optimize its performance, and to establish sustainability. This paper provides examples of several NASA products based on remote sensing and land data assimilation systems that integrate remotely sensed and in

  19. The diversity of (13)C isotope discrimination in a Quercus robur full-sib family is associated with differences in intrinsic water use efficiency, transpiration efficiency, and stomatal conductance.

    Science.gov (United States)

    Roussel, Magali; Dreyer, Erwin; Montpied, Pierre; Le-Provost, Grégoire; Guehl, Jean-Marc; Brendel, Oliver

    2009-01-01

    (13)C discrimination in organic matter with respect to atmospheric CO(2) (Delta(13)C) is under tight genetic control in many plant species, including the pedunculate oak (Quercus robur L.) full-sib progeny used in this study. Delta(13)C is expected to reflect intrinsic water use efficiency, but this assumption requires confirmation due to potential interferences with mesophyll conductance to CO(2), or post-photosynthetic discrimination. In order to dissect the observed Delta(13)C variability in this progeny, six genotypes that have previously been found to display extreme phenotypic values of Delta(13)C [either very high ('high Delta') or low ('low Delta') phenotype] were selected, and transpiration efficiency (TE; accumulated biomass/transpired water), net CO(2) assimilation rate (A), stomatal conductance for water vapour (g(s)), and intrinsic water use efficiency (W(i)=A/g(s)) were compared with Delta(13)C in bulk leaf matter, wood, and cellulose in wood. As expected, 'high Delta' displayed higher values of Delta(13)C not only in bulk leaf matter, but also in wood and cellulose. This confirmed the stability of the genotypic differences in Delta(13)C recorded earlier. 'High Delta' also displayed lower TE, lower W(i), and higher g(s). A small difference was detected in photosynthetic capacity but none in mesophyll conductance to CO(2). 'High Delta' and 'low Delta' displayed very similar leaf anatomy, except for higher stomatal density in 'high Delta'. Finally, diurnal courses of leaf gas exchange revealed a higher g(s) in 'high Delta' in the morning than in the afternoon when the difference decreased. The gene ERECTA, involved in the control of water use efficiency, leaf differentiation, and stomatal density, displayed higher expression levels in 'low Delta'. In this progeny, the variability of Delta(13)C correlated closely with that of W(i) and TE. Genetic differences of Delta(13)C and W(i) can be ascribed to differences in stomatal conductance and stomatal

  20. Seasonal, synoptic and diurnal variation of atmospheric water-isotopologues in the boundary layer of Southwestern Germany caused by plant transpiration, cold-front passages and dewfall.

    Science.gov (United States)

    Christner, Emanuel; Dyroff, Christoph; Kohler, Martin; Zahn, Andreas; Gonzales, Yenny; Schneider, Matthias

    2013-04-01

    Atmospheric water is an enormously crucial trace gas. It is responsible for ~70 % of the natural greenhouse effect (Schmidt et al., JGR, 2010) and carries huge amounts of latent heat. The isotopic composition of water vapor is an elegant tracer for a better understanding and quantification of the extremely complex and variable hydrological cycle in Earth's atmosphere (evaporation, cloud condensation, rainout, re-evaporation, snow), which in turn is a prerequisite to improve climate modeling and predictions. As H216O, H218O and HDO differ in vapor pressure and mass, isotope fractionation occurs due to condensation, evaporation and diffusion processes. In contrast to that, plants are able to transpire water with almost no isotope fractionation. For that reason the ratio of isotopologue concentrations in the boundary layer (BL) provides, compared to humidity measurements alone, independent and additional constraints for quantifying the strength of evaporation and transpiration. Furthermore the isotope ratios contain information about transport history of an air mass and microphysical processes, that is not accessible by humidity measurements. Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) a commercial Picarro Analyzer L2120-i is operated at Karlsruhe in Southwestern Germany, which is continuously measuring the isotopologues H216O, HDO and H218O of atmospheric water vapor since January 2012. A one year record of H216O, HDO and H218O shows clear seasonal, synoptic and diurnal characteristics and reveals the main driving processes affecting the isotopic composition of water vapor in the Middle European BL. Changes in continental plant transpiration and evaporation throughout the year lead to a slow seasonal HDO/H216O-variation, that cannot be explained by pure Rayleigh condensation. Furthermore, cold-front passages from NW lead to fast and pronounced depletion of the HDO/H216O-ratio within

  1. Water- and nitrogen-dependent alterations in the inheritance mode of transpiration efficiency in winter wheat at the leaf and whole-plant level.

    Science.gov (United States)

    Ratajczak, Dominika; Górny, Andrzej G

    2012-11-01

    The effects of contrasting water and nitrogen (N) supply on the observed inheritance mode of transpiration efficiency (TE) at the flag-leaf and whole-season levels were examined in winter wheat. Major components of the photosynthetic capacity of leaves and the season-integrated efficiency of water use in vegetative and grain mass formation were evaluated in parental lines of various origins and their diallel F(2)-hybrids grown in a factorial experiment under different moisture and N status of the soil. A broad genetic variation was mainly found for the season-long TE measures. The variation range in the leaf photosynthetic indices was usually narrow, but tended to slightly enhance under water and N shortage. Genotype-treatment interaction effects were significant for most characters. No consistency between the leaf- and season-long TE measures was observed. Preponderance of additivity-dependent variance was mainly identified for the season-integrated TE and leaf CO(2) assimilation rate. Soil treatments exhibited considerable influence on the phenotypic expression of gene action for the residual leaf measures. The contribution of non-additive gene effects and degree of dominance tended to increase in water- and N-limited plants, especially for the leaf transpiration rate and stomatal conductance. The results indicate that promise exists to improve the season-integrated TE. However, selection for TE components should be prolonged for later hybrid generations to eliminate the masking of non-additive causes. Such evaluation among families grown under sub-optimal water and nitrogen supply seems to be the most promising strategy in winter wheat.

  2. Remetabolism of transpired ethanol by Populus deltoides

    International Nuclear Information System (INIS)

    MacDonald, R.C.; Kimmerer, T.W.

    1990-01-01

    Ethanol is present in the transpiration stream of flooded and unflooded trees in concentrations up to 0.5mM. Transpired ethanol does not evaporate but is remetabolized by foliage and upper stems in Populus deltoides. 14 C-ethanol was supplied in the transpiration stream to excised leaves and shoots; more than 98% was incorporated. Less than 1% was respired as CO 2 . Organic and amino acids were labelled initially, with eventual accumulations in water- and chloroform-soluble fractions and into protein. Much of the label was incorporated into stem tissue, with little reaching the lamina. These experiments suggest that ethanol is not lost transpirationally through the leaves, but is efficiently recycled in a manner resembling lactate recycling in mammals

  3. Net CO2 and water exchanges of trees and grasses in a semi-arid region (Gourma, Mali)

    Science.gov (United States)

    Le Dantec, Valérie; Kergoat, Laurent; Timouk, Franck; Hiernaux, Pierre; Mougin, Eric

    2010-05-01

    An improved understanding of plant and soil processes is critical to predict land surface-atmosphere water exchanges, especially in semi-arid environments, where knowledge is still severely lacking. Within the frame of the African Monsoon Multidisciplinary Project (AMMA), eddy covariance and sapflow stations have been installed to document the intensity, the temporal variability and the main drivers of net CO2 fluxes, water fluxes and contribution of the trees to these fluxes in a pastoral Sahelian landscape. Indeed, although the importance of vegetation in the West African monsoon system has long been postulated, extremely few data were available sofar to test and develop land surface models. In particular, data documenting seasonal and inter-annual dynamics of vegetation/atmosphere exchanges did not exist at 15° N in West Africa before AMMA. The site is located in the Gourma, Mali. Vegetation in this area is sparse and mainly composed of annual grasses and forbs, and trees. Vegetation is organized according to soil type and lateral water redistribution, with bare soil with scattered trees on shallow soils and rocky outcrops (35% of the area), annual grasses and scattered trees on sandy soils (65% of the area), and more dense canopies of grasses and trees growing in valley bottoms over clay soil. To quantify tree transpiration in the overall evapotranspiration flux, sapflow measurements, associated to soil moisture measurements, have been conducted on the main tree species (Acacia senegal, A. seyal, A. raddiana, Combretum glutinosum, Balanites aegyptiaca) in a grassland site and in an open forest site, where eddy covariance fluxes measured the total flux. Using this dataset, we have studied the effects of plant diversity on carbon and water fluxes at the foot-print scale and seasonal dynamics of fluxes due to plant phenology and variations of soil water content (SWC). Carbon fluxes were documented as well, over two years. NEE was close to 0 during the dry season

  4. Combining field performance with controlled environment plant imaging to identify the genetic control of growth and transpiration underlying yield response to water-deficit stress in wheat.

    Science.gov (United States)

    Parent, Boris; Shahinnia, Fahimeh; Maphosa, Lance; Berger, Bettina; Rabie, Huwaida; Chalmers, Ken; Kovalchuk, Alex; Langridge, Peter; Fleury, Delphine

    2015-09-01

    Crop yield in low-rainfall environments is a complex trait under multigenic control that shows significant genotype×environment (G×E) interaction. One way to understand and track this trait is to link physiological studies to genetics by using imaging platforms to phenotype large segregating populations. A wheat population developed from parental lines contrasting in their mechanisms of yield maintenance under water deficit was studied in both an imaging platform and in the field. We combined phenotyping methods in a common analysis pipeline to estimate biomass and leaf area from images and then inferred growth and relative growth rate, transpiration, and water-use efficiency, and applied these to genetic analysis. From the 20 quantitative trait loci (QTLs) found for several traits in the platform, some showed strong effects, accounting for between 26 and 43% of the variation on chromosomes 1A and 1B, indicating that the G×E interaction could be reduced in a controlled environment and by using dynamic variables. Co-location of QTLs identified in the platform and in the field showed a possible common genetic basis at some loci. Co-located QTLs were found for average growth rate, leaf expansion rate, transpiration rate, and water-use efficiency from the platform with yield, spike number, grain weight, grain number, and harvest index in the field. These results demonstrated that imaging platforms are a suitable alternative to field-based screening and may be used to phenotype recombinant lines for positional cloning. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  5. Business Profile of Boat Lift Net and Stationary Lift Net Fishing Gear in Morodemak Waters Central Java

    Science.gov (United States)

    Hapsari, Trisnani D.; Jayanto, Bogi B.; Fitri, Aristi D. P.; Triarso, I.

    2018-02-01

    Lift net is one of the fishing gears that is used widely in the Morodemak coastal fishing port (PPP) for catching pelagic fish. The yield of fish captured by these fishing gear has high economic value, such as fish belt (Trichiurus sp), squids (Loligo sp) and anchovies (Stelophorus sp). The aims of this research were to determine the technical aspects of boat lift net and stationary lift net fishing gear in Morodemak Waters Demak Regency; to find out the financial aspect of those fishing gears and to analyze the financial feasibility by counting PP, NPV, IRR, and B/C ratio criteria. This research used case study method with descriptive analysis. The sampling method was purposive sampling with 22 fishermen as respondents. The result of the research showed that the average of boat lift net acceptance was Rp 388,580,000. The financial analysis of fisheries boat lift net with the result of NPV Rp 836,149,272, PP 2.44 years, IRR value 54%, and B/C ratio 1.73. The average of stationary lift net acceptance was Rp 27,750,000. The financial analysis lift net with the result of NPV Rp 37,937,601; PP 1.96 years, IRR value 86%, and B/C ratio 1.32. This research had a positive NPV value, B/C ratio >1, and IRR > discount rate (12 %). This study concluded that the fishery business of boat lift net and stationary lift net in Morodemak coastal fishing port (PPP) was worth running.

  6. Coordination of Leaf Photosynthesis, Transpiration, and Structural Traits in Rice and Wild Relatives (Genus Oryza).

    Science.gov (United States)

    Giuliani, Rita; Koteyeva, Nuria; Voznesenskaya, Elena; Evans, Marc A; Cousins, Asaph B; Edwards, Gerald E

    2013-07-01

    The genus Oryza, which includes rice (Oryza sativa and Oryza glaberrima) and wild relatives, is a useful genus to study leaf properties in order to identify structural features that control CO(2) access to chloroplasts, photosynthesis, water use efficiency, and drought tolerance. Traits, 26 structural and 17 functional, associated with photosynthesis and transpiration were quantified on 24 accessions (representatives of 17 species and eight genomes). Hypotheses of associations within, and between, structure, photosynthesis, and transpiration were tested. Two main clusters of positively interrelated leaf traits were identified: in the first cluster were structural features, leaf thickness (Thick(leaf)), mesophyll (M) cell surface area exposed to intercellular air space per unit of leaf surface area (S(mes)), and M cell size; a second group included functional traits, net photosynthetic rate, transpiration rate, M conductance to CO(2) diffusion (g(m)), stomatal conductance to gas diffusion (g(s)), and the g(m)/g(s) ratio.While net photosynthetic rate was positively correlated with gm, neither was significantly linked with any individual structural traits. The results suggest that changes in gm depend on covariations of multiple leaf (S(mes)) and M cell (including cell wall thickness) structural traits. There was an inverse relationship between Thick(leaf) and transpiration rate and a significant positive association between Thick(leaf) and leaf transpiration efficiency. Interestingly, high g(m) together with high g(m)/g(s) and a low S(mes)/g(m) ratio (M resistance to CO(2) diffusion per unit of cell surface area exposed to intercellular air space) appear to be ideal for supporting leaf photosynthesis while preserving water; in addition, thick M cell walls may be beneficial for plant drought tolerance.

  7. Selection of black poplars for water use efficiency

    OpenAIRE

    Orlović Saša S.; Pajević Slobodanka P.; Krstić Borivoj Đ.

    2002-01-01

    Photosynthesis, transpiration, water use efficiency (WUE) and biomass production have been investigated in nine black poplar clones (section Aigeiros) in three field experiments. Eastern cottonwood clones (Populus deltoides) had the highest net photosynthesis and water use efficiency. European black poplar clones had the highest transpiration intensity. Correlation analysis showed that net photosynthesis was in a high positive correlation with biomass. Medium negative correlations existed bet...

  8. Whole-tree transpiration and water-use partitioning between Eucalyptus nitens and Acacia dealbata weeds in a short-rotation plantation in northeastern Tasmania.

    Science.gov (United States)

    Hunt, Mark A.; Beadle, Christopher L.

    1998-01-01

    Whole-tree water use in 4- and 8-year-old plantations of Eucalyptus nitens Deane and Maiden (ex Maiden) in the presence and absence of Acacia dealbata Link. weeds was estimated by the heat pulse velocity technique during a six-week summer period. Maximum sap velocities were recorded between 5 and 15 mm under the cambium for both eucalypt and acacia trees, and marked radial and axial variations in sap velocity were observed. The latter source of variation was most pronounced in mixed stands where crowns were asymmetrical. Mean daily sap flux ranged from 1.4 to 103.6 l day(-1) for eucalypts and from acacias. Stem diameter explained 98% of the variation in sapwood area for E. nitens and 89% for A. dealbata, and was determined to be a suitable parameter for scaling water use from the tree to stand level. Plot transpiration varied from 1.4 to 2.8 mm day(-1) in mixed 8-year-old plots and was 0.85 mm day(-1) in a mixed 4-year-old plot. The degree of A. dealbata infestation was associated with absolute plot water use and regression models predicted that, in the absence of acacia competition, plot water use for the 8-year-old stand would approach 5-6 mm day(-1) during the growing season.

  9. Hydraulic Limits on Maximum Plant Transpiration

    Science.gov (United States)

    Manzoni, S.; Vico, G.; Katul, G. G.; Palmroth, S.; Jackson, R. B.; Porporato, A. M.

    2011-12-01

    Photosynthesis occurs at the expense of water losses through transpiration. As a consequence of this basic carbon-water interaction at the leaf level, plant growth and ecosystem carbon exchanges are tightly coupled to transpiration. In this contribution, the hydraulic constraints that limit transpiration rates under well-watered conditions are examined across plant functional types and climates. The potential water flow through plants is proportional to both xylem hydraulic conductivity (which depends on plant carbon economy) and the difference in water potential between the soil and the atmosphere (the driving force that pulls water from the soil). Differently from previous works, we study how this potential flux changes with the amplitude of the driving force (i.e., we focus on xylem properties and not on stomatal regulation). Xylem hydraulic conductivity decreases as the driving force increases due to cavitation of the tissues. As a result of this negative feedback, more negative leaf (and xylem) water potentials would provide a stronger driving force for water transport, while at the same time limiting xylem hydraulic conductivity due to cavitation. Here, the leaf water potential value that allows an optimum balance between driving force and xylem conductivity is quantified, thus defining the maximum transpiration rate that can be sustained by the soil-to-leaf hydraulic system. To apply the proposed framework at the global scale, a novel database of xylem conductivity and cavitation vulnerability across plant types and biomes is developed. Conductivity and water potential at 50% cavitation are shown to be complementary (in particular between angiosperms and conifers), suggesting a tradeoff between transport efficiency and hydraulic safety. Plants from warmer and drier biomes tend to achieve larger maximum transpiration than plants growing in environments with lower atmospheric water demand. The predicted maximum transpiration and the corresponding leaf water

  10. 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

    . Data were collected daily in a laboratory, under a photosynthetic photon flux (PPF of 1200 mum-2 s-1, and studied by variance and regression analysis. Significant decreases of leaf water potential values and gas exchange rates were verified when water was withhold for more than six days. The smallest values were found at the tenth day without water replacement, with a reduction of 92% of the net photosynthetic rate, 87% of the stomatal conductance and 70% of the transpiration. By that time, the smallest measured leaf water potential was --1.9 MPa. Recovering from water stress was accomplished two days after rewatering, except for stomatal conductance. The partial closing of the stomata (decrease in stomatal conductance and the reduction of photosynthesis, suggest the existence of an acclimation mechanism of the peach palm, diminishing water loss under moderate stress.

  11. 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...

  12. Net-bottom Cage Inserts for Water Bird Casualties

    Directory of Open Access Journals (Sweden)

    Jackie Belle

    2017-10-01

    Full Text Available My Bright Idea is a net-bottomed cage insert, which is used to support pelagic avian casualties. The idea was designed and modified by the International Bird Rescue in California (Bird Rescue.

  13. Genetic variation in a grapevine progeny (Vitis vinifera L. cvs Grenache×Syrah) reveals inconsistencies between maintenance of daytime leaf water potential and response of transpiration rate under drought

    Science.gov (United States)

    Coupel-Ledru, Aude; Lebon, Éric; Christophe, Angélique; Doligez, Agnès; Cabrera-Bosquet, Llorenç; Péchier, Philippe; Hamard, Philippe; This, Patrice; Simonneau, Thierry

    2014-01-01

    In the face of water stress, plants evolved with different abilities to limit the decrease in leaf water potential, notably in the daytime (ΨM). So-called isohydric species efficiently maintain high ΨM, whereas anisohydric species cannot prevent ΨM from dropping as soil water deficit develops. The genetic and physiological origins of these differences in (an)isohydric behaviours remain to be clarified. This is of particular interest within species such as Vitis vinifera L. where continuous variation in the level of isohydry has been observed among cultivars. With this objective, a 2 year experiment was conducted on the pseudo-F1 progeny from a cross between the two widespread cultivars Syrah and Grenache using a phenotyping platform coupled to a controlled-environment chamber. Potted plants of all the progeny were analysed for ΨM, transpiration rate, and soil-to-leaf hydraulic conductance, under both well-watered and water deficit conditions. A high genetic variability was found for all the above traits. Four quantitative trait loci (QTLs) were detected for ΨM under water deficit conditions, and 28 other QTLs were detected for the different traits in either condition. Genetic variation in ΨM maintenance under water deficit weakly correlated with drought-induced reduction in transpiration rate in the progeny, and QTLs for both traits did not completely co-localize. This indicates that genetic variation in the control of ΨM under water deficit was not due simply to variation in transpiration sensitivity to soil drying. Possible origins of the diversity in (an)isohydric behaviours in grapevine are discussed on the basis of concurrent variations in soil-to-leaf hydraulic conductance and stomatal control of transpiration. PMID:25381432

  14. Mineralizing urban net-zero water treatment: Phase II field results and design recommendations

    Science.gov (United States)

    Net-zero water (NZW) systems, or water management systems achieving high recycling rates and low residuals generation so as to avoid water import and export, can also conserve energy used to heat and convey water, while economically restoring local eco-hydrology. However, design ...

  15. Transpiration and water potential of young Quercus petraea (M.) Liebl. coppice sprouts and seedlings during favourable and drought conditions

    Czech Academy of Sciences Publication Activity Database

    Stojanović, Marko; Szatniewska, Justyna; Kyselová, Ina; Pokorný, R.; Čater, M.

    2017-01-01

    Roč. 63, č. 7 (2017), s. 313-323 ISSN 1212-4834 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : sessile oak * management system * comparison * sap flow * leaf water potential * water availability Subject RIV: EH - Ecology, Behaviour OBOR OECD: Environmental sciences (social aspects to be 5.7) http://www.agriculturejournals.cz/web/jfs.htm?type=article&id=36_2017-JFS

  16. Water relations, stomatal response and transpiration of Quercus pubescens trees during summer in a Mediterranean carbon dioxide spring

    Energy Technology Data Exchange (ETDEWEB)

    Tognetti, R.; Miglietta, F.; Raschi, A. [Consiglio Nazionale della Ricerche, Firenze (Italy); Longobucco, A. [Centro Studi per l`Informatica applicata all`Agricoltura, Firenze (Italy)

    1999-04-01

    Variations in water relations and stomatal response of downy oak (Quercus pubescens) were analyzed under Mediterranean field conditions during two consecutive summers at two locations characterized by different atmospheric CO{sub 2} concentrations due to the presence of a CO{sub 2} spring at one of the locations. The heat-pulse velocity technique was used to estimate water use during a five-month period from June to November 1994. At the end of the sap flow measurements, the trees were harvested and foliage and sapwood area measured. The effect of elevated CO{sub 2} concentration on leaf conductance was less at high leaf-to-air water vapour pressure difference than at low leaf-to-air water vapour pressure difference. Mean and diurnal sap fluxes were consistently higher in trees at the control site than in the trees at the CO{sub 2} spring site. Results are discussed in terms of effects of elevated CO{sub 2} concentration on plant water use at the organ and whole-tree level. 76 refs., 9 figs.

  17. Warmer temperatures reduce net carbon uptake, but not water use, in a mature southern Appalachian forest

    Science.gov (United States)

    Increasing air temperature is expected to extend growing season length in temperate, broadleaf forests, leading to potential increases in evapotranspiration and net carbon uptake. However, other key processes affecting water and carbon cycles are also highly temperature-dependent...

  18. 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

  19. Reply to Miglietta et al.: Maximal transpiration controlled by plants

    NARCIS (Netherlands)

    Boer, H.J. de; Lammertsma, E.I.; Wagner-Cremer, F.; Dilcher, D.L.; Wassen, M.J.; Dekker, S.C.

    2011-01-01

    We thank Miglietta et al. for their interest in our study. Their first and main point arises from the idea that plant transpiration (T) is driven by atmospheric demand, giving plants limited control over the water they lose...

  20. 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.

  1. 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

    2016-01-01

    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. PMID:26802540

  2. Effect of water stress on carbon isotope discrimination and its relationship with transpiration efficiency and specific leaf area in Cenchrus species.

    Science.gov (United States)

    Dubey, Archana; Chandra, Amaresh

    2008-05-01

    Carbon isotope discrimination (CID) has been proposed in estimating transpiration efficiency (TE) in plants indirectly To identify variations for TE and specific leaf area (SLA) and their association with CID, a glasshouse experiment was conducted using six prominent species of Cenchrus. A significant increase in TE (3.50 to 3.87 g kg(-1)) and decrease in SLA (219.50 to 207.99 cm2 g(-1)) and CID (13.72 to 13.23% per hundred) was observed from well watered to stress condition. Results indicated a direct relationship of SLA with CID (r = 0.511* and 0.544*) and inverse relationship between TE and CID (r = -0.229 and -0.270) However the relationship of TE with CID was insignificant. A positive and significant relationship was visualized between TE and dry matter production in both control (r = 0.917**) and stress (0.718**) treatments. Relationships of total dry matter with SLA and CID were monitored insignificant and negative in control and positive in stress treatment indicated difference in dry matter production under two treatments. It seems that, in Cenchrus species, CID was influenced more by the photosynthetic capacity than by stomatal conductance, as indicated by its positive relationship with SLAin both control (r = 0.511) and stress (r = 0.544) conditions and negative relationship with root dry matter production under control (r = -0.921**) and stress (r = -0.919***) condition. Results showed good correspondence between CID and SLA, indicating that lines having high TE and biomass production can be exploited for their genetic improvement for drought.

  3. Daily course of transpiration productivity

    Energy Technology Data Exchange (ETDEWEB)

    Koch, W

    1957-01-01

    THIS STUDY OF THE RELATIONSHIP BETWEEN TRANSPIRATION AND DRY-MATTER PRODUCTION OF FIELD CROPS, INCLUDED ALSO INVESTIGATIONS OF NEEDLES OF SPRUCE AND SILVER FIR SUFFERING FROM SO/sup 3/ DAMAGE, IN WHICH A MARKED INCREASE IN TRANSPIRATION PRODUCTIVITY WAS NOTED. 25 REFERENCES, 32 FIGURES.

  4. Mineralizing urban net-zero water treatment: Field experience for energy-positive water management.

    Science.gov (United States)

    Wu, Tingting; Englehardt, James D

    2016-12-01

    An urban net-zero water treatment system, designed for energy-positive water management, 100% recycle of comingled black/grey water to drinking water standards, and mineralization of hormones and other organics, without production of concentrate, was constructed and operated for two years, serving an occupied four-bedroom, four-bath university residence hall apartment. The system comprised septic tank, denitrifying membrane bioreactor (MBR), iron-mediated aeration (IMA) reactor, vacuum ultrafilter, and peroxone or UV/H 2 O 2 advanced oxidation, with 14% rainwater make-up and concomitant discharge of 14% of treated water (ultimately for reuse in irrigation). Chemical oxygen demand was reduced to 12.9 ± 3.7 mg/L by MBR and further decreased to below the detection limit (treatment. The process produced a mineral water meeting 115 of 115 Florida drinking water standards that, after 10 months of recycle operation with ∼14% rainwater make-up, had a total dissolved solids of ∼500 mg/L, pH 7.8 ± 0.4, turbidity 0.12 ± 0.06 NTU, and NO 3 -N concentration 3.0 ± 1.0 mg/L. None of 97 hormones, personal care products, and pharmaceuticals analyzed were detected in the product water. For a typical single-home system with full occupancy, sludge pumping is projected on a 12-24 month cycle. Operational aspects, including disinfection requirements, pH evolution through the process, mineral control, advanced oxidation by-products, and applicability of point-of-use filters, are discussed. A distributed, peroxone-based NZW management system is projected to save more energy than is consumed in treatment, due largely to retention of wastewater thermal energy. Recommendations regarding design and operation are offered. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Can net photosynthesis and water relations provide a clue on the ...

    African Journals Online (AJOL)

    Net photosynthesis, sap flow density (SFD) and water use efficiency (WUE) were measured in a Quercus suber forest in north Tunisia in an attempt to explain the forest decline. In general, sap flow was positively related to light intensity and water loss, indicating that high light intensities can increase the SFD up to the ...

  6. Tuning Transpiration by Interfacial Solar Absorber-Leaf Engineering.

    Science.gov (United States)

    Zhuang, Shendong; Zhou, Lin; Xu, Weichao; Xu, Ning; Hu, Xiaozhen; Li, Xiuqiang; Lv, Guangxin; Zheng, Qinghui; Zhu, Shining; Wang, Zhenlin; Zhu, Jia

    2018-02-01

    Plant transpiration, a process of water movement through a plant and its evaporation from aerial parts especially leaves, consumes a large component of the total continental precipitation (≈48%) and significantly influences global water distribution and climate. To date, various chemical and/or biological explorations have been made to tune the transpiration but with uncertain environmental risks. In recent years, interfacial solar steam/vapor generation is attracting a lot of attention for achieving high energy transfer efficiency. Various optical and thermal designs at the solar absorber-water interface for potential applications in water purification, seawater desalination, and power generation appear. In this work, the concept of interfacial solar vapor generation is extended to tunable plant transpiration by showing for the first time that the transpiration efficiency can also be enhanced or suppressed through engineering the solar absorber-leaf interface. By tuning the solar absorption of membrane in direct touch with green leaf, surface temperature of green leaf will change accordingly because of photothermal effect, thus the transpiration efficiency as well as temperature and relative humidity in the surrounding environment will be tuned. This tunable transpiration by interfacial absorber-leaf engineering can open an alternative avenue to regulate local atmospheric temperature, humidity, and eventually hydrologic cycle.

  7. Tuning Transpiration by Interfacial Solar Absorber‐Leaf Engineering

    Science.gov (United States)

    Zhuang, Shendong; Zhou, Lin; Xu, Weichao; Xu, Ning; Hu, Xiaozhen; Li, Xiuqiang; Lv, Guangxin; Zheng, Qinghui; Zhu, Shining

    2017-01-01

    Abstract Plant transpiration, a process of water movement through a plant and its evaporation from aerial parts especially leaves, consumes a large component of the total continental precipitation (≈48%) and significantly influences global water distribution and climate. To date, various chemical and/or biological explorations have been made to tune the transpiration but with uncertain environmental risks. In recent years, interfacial solar steam/vapor generation is attracting a lot of attention for achieving high energy transfer efficiency. Various optical and thermal designs at the solar absorber–water interface for potential applications in water purification, seawater desalination, and power generation appear. In this work, the concept of interfacial solar vapor generation is extended to tunable plant transpiration by showing for the first time that the transpiration efficiency can also be enhanced or suppressed through engineering the solar absorber–leaf interface. By tuning the solar absorption of membrane in direct touch with green leaf, surface temperature of green leaf will change accordingly because of photothermal effect, thus the transpiration efficiency as well as temperature and relative humidity in the surrounding environment will be tuned. This tunable transpiration by interfacial absorber‐leaf engineering can open an alternative avenue to regulate local atmospheric temperature, humidity, and eventually hydrologic cycle. PMID:29619300

  8. Sap flow measurements to determine the transpiration of facade greenings

    Science.gov (United States)

    Hölscher, Marie-Therese; Nehls, Thomas; Wessolek, Gerd

    2014-05-01

    Facade greening is expected to make a major contribution to the mitigation of the urban heat-island effect through transpiration cooling, thermal insulation and shading of vertical built structures. However, no studies are available on water demand and the transpiration of urban vertical green. Such knowledge is needed as the plants must be sufficiently watered, otherwise the posited positive effects of vertical green can turn into disadvantages when compared to a white wall. Within the framework of the German Research Group DFG FOR 1736 "Urban Climate and Heat Stress" this study aims to test the practicability of the sap flow technique for transpiration measurements of climbing plants and to obtain potential transpiration rates for the most commonly used species. Using sap flow measurements we determined the transpiration of Fallopia baldschuanica, Parthenocissus tricuspidata and Hedera helix in pot experiments (about 1 m high) during the hot summer period from August 17th to August 30th 2012 under indoor conditions. Sap flow measurements corresponded well to simultaneous weight measurement on a daily base (factor 1.19). Fallopia baldschuanica has the highest daily transpiration rate based on leaf area (1.6 mm d-1) and per base area (5.0 mm d-1). Parthenocissus tricuspidata and Hedera helix show transpiration rates of 3.5 and 0.4 mm d-1 (per base area). Through water shortage, transpiration strongly decreased and leaf temperature measured by infrared thermography increased by 1 K compared to a well watered plant. We transferred the technique to outdoor conditions and will present first results for facade greenings in the inner-city of Berlin for the hottest period in summer 2013.

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

    Science.gov (United States)

    Chen, Lixin; Zhang, Zhiqiang; Li, Zhandong; Tang, Jianwu; Caldwell, Peter; Zhang, Wenjuan

    2011-05-01

    SummaryUrban 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 the biophysical control of the transpiration pattern under different water conditions to understand how trees survive in an urban environment. Concurrent with microclimate and soil moisture measurements, transpiration from C edrus deodara(Roxb)Loud ., Zelkova schneideriana Hend.-Mazz., Euonymus bungeanus Maxim., and Metasequoia glyptostroboides Hu et cheng was measured over a 2-year period using thermal dissipation probe (TDP) techniques. The average monthly transpiration rates reached 12.78 ± 0.73 (S.E.) mm, 1.79 ± 0.16 mm, 10.18 ± 0.55 mm and 19.28 ± 2.24 mm for C. deodara, Z.schneideriana, E. bungeanus and M. glyptostroboides, respectively. Transpiration rates from M. glyptostroboides reported here may need further study as this species showed much higher sap flows and greater transpiration fluctuation under different environmental conditions than other species. Because of deep soil moisture supply, summer dry spells did not reduce transpiration rates even when tree transpiration exceeded rainfall. While vapor pressure deficit ( VPD) was the dominant environmental factor on transpiration, trees controlled canopy conductance effectively to limit transpiration in times of water stress. Our results provide evidence that urban trees could adopt strong physiological control over transpiration under high evaporative demands to avoid dehydration and can make use of water in deeper soil layers to survive summer dry spells. Moreover, urban trees have the ability to make the best use of precipitation when it is limited, and are sensitive to soil and air dryness.

  10. UV sensitivity of planktonic net community production in ocean surface waters

    OpenAIRE

    Regaudie de Gioux, Aurore; Agustí, Susana; Duarte, Carlos M.

    2014-01-01

    The net plankton community metabolism of oceanic surface waters is particularly important as it more directly affects the partial pressure of CO2 in surface waters and thus the air-sea fluxes of CO2. Plankton communities in surface waters are exposed to high irradiance that includes significant ultraviolet blue (UVB, 280-315 nm) radiation. UVB radiation affects both photosynthetic and respiration rates, increase plankton mortality rates, and other metabolic and chemical processes. Here we tes...

  11. Irrigation Alternatives to Meet Army Net Zero Water Goals

    Science.gov (United States)

    2012-05-01

    Use of mulches  Appropriate maintenance BUILDING STRONG® Soil Additives/Amendments  Maximize soil moisture retention ► Compost to improve water...holding capacity ►Polyacrylamides to prolong soil moisture release ► Ideal soil texture (mix of clay, silt, and sand) maintained to adequate depths...BUILDING STRONG® Mulches  Organic ► Compost ►Shredded barks and other landscape wastes  Inorganic ►Gravel ►Rock ►Crumb rubber ►Fabrics and

  12. UV sensitivity of planktonic net community production in ocean surface waters

    Science.gov (United States)

    Regaudie-de-Gioux, Aurore; Agustí, Susana; Duarte, Carlos M.

    2014-05-01

    The net plankton community metabolism of oceanic surface waters is particularly important as it more directly affects the partial pressure of CO2 in surface waters and thus the air-sea fluxes of CO2. Plankton communities in surface waters are exposed to high irradiance that includes significant ultraviolet blue (UVB, 280-315 nm) radiation. UVB radiation affects both photosynthetic and respiration rates, increase plankton mortality rates, and other metabolic and chemical processes. Here we test the sensitivity of net community production (NCP) to UVB of planktonic communities in surface waters across contrasting regions of the ocean. We observed here that UVB radiation affects net plankton community production at the ocean surface, imposing a shift in NCP by, on average, 50% relative to the values measured when excluding partly UVB. Our results show that under full solar radiation, the metabolic balance shows the prevalence of net heterotrophic community production. The demonstration of an important effect of UVB radiation on NCP in surface waters presented here is of particular relevance in relation to the increased UVB radiation derived from the erosion of the stratospheric ozone layer. Our results encourage design future research to further our understanding of UVB effects on the metabolic balance of plankton communities.

  13. Efeito do déficit hídrico na transpiração e resistência estomática da mangueira Effect of water deficit on the transpiration and stomatal resistance of mango tree

    Directory of Open Access Journals (Sweden)

    Manoel Teixeira de Castro Neto

    2003-04-01

    Full Text Available O processo de indução floral da mangueira no Nordeste brasileiro, mediante o uso do déficit hídrico, não tem dado resultado satisfatório, principalmente pelo manejo inadequado da irrigação. O processo transpiratório e a resistência estomática da mangueira refletem a condição hídrica da planta. O monitoramento destes parâmetros fisiológicos na mangueira, durante o período de repouso fisiológico e irrigado, sugere que a indução floral por déficit hídrico não é eficiente devido ao manejo incorreto da irrigação.Flowering induction of mango growth at the Northeast Brazil has not given satisfactory results mainly due to inadequate irrigation management. Transpiration and stomatal resistance of mango trees can reflect the water status of the plant. Monitoring the transpiration and stomatal resistance of mango trees during water deficit and irrigation period suggests that the flower induction by water deficit is not efficient due to incorrect irrigation management.

  14. 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.

  15. Seasonal and Topographic Variation in Net Primary Productivity and Water Use Efficiency in a Southwest Sky Island Fores

    Science.gov (United States)

    Murphy, P.; Minor, R. L.; Sanchez-Canete, E. P.; Potts, D. L.; Barron-Gafford, G.

    2016-12-01

    Western North American Forests represent an uncertain sink for atmospheric carbon. While understanding of the physical drivers of productivity in these forests has grown in the last decade, the relative influence of topographic position in the complex terrain of montane systems remains understudied. The high-latitude mixed conifer forest ecosystems of the southern Arizona Madrean Sky Islands are characterized by low precipitation, high annual variation in temperature, and heterogeneous topography. Eddy covariance measurements these forests show distinct seasonal trends due to temperature and bi-modal precipitation patterns, but these measurements are unable to resolve potential differences in physiological function on opposing north and south aspects within the footprint of the tower. Most of the year, north aspects receive less energy input due to the oblique angle of incoming solar radiation, leading to a divergence in soil moistures and temperatures. However, overall movement of energy and material is much higher on these north aspects on an annual basis. The implications of these differences for net primary productivity (NPP) and water use efficiency (WUE) are poorly addressed in the literature. We evaluated the relative control that topography has on the physical environment (soil moisture and temperature) and how these factors affect water stress, NPP, and WUE. We combined leaf-level measurements of photosynthesis and transpiration with other physiological and meteorological measurements to determine how the dominant vegetation functions as a result of microclimatic conditions. Initial results from the spring and summer measurement periods suggest topographical differences in microclimate, resulting in differences in NPP in the spring, but not the summer. Also, each of the three species on the same aspect responded differently to the same microclimatic conditions, underscoring interspecific variation at the site. How might these patterns change throughout an

  16. [Response processes of Aralia elata photosynthesis and transpiration to light and soil moisture].

    Science.gov (United States)

    Chen, Jian; Zhang, Guang-Can; Zhang, Shu-Yong; Wang, Meng-Jun

    2008-06-01

    By using CIRAS-2 portable photosynthesis system, the light response processes of Aralia elata photosynthesis and transpiration under different soil moisture conditions were studied, aimed to understand the adaptability of A. elata to different light and soil moisture conditions. The results showed that the response processes of A. elata net photosynthetic rate (Pn), transpiration rate (Tr), and water use efficiency (WUE) to photon flux density (PFD) were different. With the increasing PFD in the range of 800-1800 micromol x m2(-2) x s(-1), Pn changed less, Tr decreased gradually, while WUE increased obviously. The light saturation point (LSP) and light compensation point (LCP) were about 800 and 30 micromol m(-2) x s(-1), respectively, and less affected by soil water content; while the apparent photosynthetic quantum yield (Phi) and dark respiratory rate (Rd) were more affected by the moisture content. The Pn and WUE had evident threshold responses to the variations of soil water content. When the soil relative water content (RWC) was in the range of 44%-79%, A. elata could have higher levels of Pn and WUE.

  17. TIGER-NET – enabling an Earth Observation capacity for Integrated Water Resource Management in Africa

    DEFF Research Database (Denmark)

    Walli, A.; Tøttrup, C.; Naeimi, V.

    As part of the TIGER initiative [1] the TIGER-NET project aims to support the assessment and monitoring of water resources from watershed to transboundary basin level delivering indispensable information for Integrated Water Resource Management in Africa through: 1. Development of an open......-source Water Observation and Information Systems (WOIS) for monitoring, assessing and inventorying water resources in a cost-effective manner; 2. Capacity building and training of African water authorities and technical centers to fully exploit the increasing observation capacity offered by current...... and upcoming generations of satellites, including the Sentinel missions. Dedicated application case studies have been developed and demonstrated covering all EO products required by and developed with the participating African water authorities for their water resource management tasks, such as water reservoir...

  18. Role of aquaporins in determining transpiration and photosynthesis in water-stressed plants: crop water-use efficiency, growth and yield.

    Science.gov (United States)

    Moshelion, Menachem; Halperin, Ofer; Wallach, Rony; Oren, Ram; Way, Danielle A

    2015-09-01

    The global shortage of fresh water is one of our most severe agricultural problems, leading to dry and saline lands that reduce plant growth and crop yield. Here we review recent work highlighting the molecular mechanisms allowing some plant species and genotypes to maintain productivity under water stress conditions, and suggest molecular modifications to equip plants for greater production in water-limited environments. Aquaporins (AQPs) are thought to be the main transporters of water, small and uncharged solutes, and CO2 through plant cell membranes, thus linking leaf CO2 uptake from the intercellular airspaces to the chloroplast with water loss pathways. AQPs appear to play a role in regulating dynamic changes of root, stem and leaf hydraulic conductivity, especially in response to environmental changes, opening the door to using AQP expression to regulate plant water-use efficiency. We highlight the role of vascular AQPs in regulating leaf hydraulic conductivity and raise questions regarding their role (as well as tonoplast AQPs) in determining the plant isohydric threshold, growth rate, fruit yield production and harvest index. The tissue- or cell-specific expression of AQPs is discussed as a tool to increase yield relative to control plants under both normal and water-stressed conditions. © 2014 John Wiley & Sons Ltd.

  19. Role of transpiration reduction during center-pivot sprinkler irrigation in application efficiency

    OpenAIRE

    Urrego Pereira, Yenny Fernanda; Cavero Campo, José; Medina Pueyo, Eva Teresa; Martínez-Cob, Antonio

    2013-01-01

    The magnitude and duration of corn transpiration reduction during center-pivot sprinkler irrigation was analyzed on a commercial plot. The irrigation event was defined as the period during which the pivot arm was passing over the transect AC and water droplets were moistening the plants (moist treatment). Corn transpiration rates were measured at three spots of that transect and simultaneously at another spot (dry treatment) located approximately 270 m east from the transect AC. Corn transpir...

  20. Transpiration efficiency of three Mediterranean annual pasture species and wheat.

    Science.gov (United States)

    Bolger, T P; Turner, N C

    1998-06-01

    Attempts to improve water use efficiency in regions with Mediterranean climates generally focus on increasing plant transpiration relative to evaporation from the soil and increasing transpiration efficiency. Our aim was to determine if transpiration efficiency differs among key species occurring in annual pastures in southern Australia. Two glasshouse experiments were conducted with three key pasture species, subterranean clover (Trifolium subterraneum L.), capeweed [Arctotheca calendula (L.) Levyns] and annual ryegrass (Lolium rigidum Gaudin), and wheat (Triticum aestivum L.). Transpiration efficiency was assessed at the levels of␣whole-plant biomass and water use (W), leaf gas exchange measurements of the ratio of CO 2 assimilation to leaf conductance to water vapour (A/g), and carbon isotope discrimination (Δ) in leaf tissue. In addition, Δ was measured on shoots of the three pasture species growing together in the field. In the glasshouse studies, annual ryegrass had a consistently higher transpiration efficiency than subterranean clover or capeweed by all methods of measurement. Subterranean clover and capeweed had similar transpiration efficiencies by all three methods of measurement. Wheat had W values similar to ryegrass but A/g and Δ values similar to subterranean clover or capeweed. The high W of annual ryegrass seems to be related to a conservative leaf gas exchange behaviour, with lower assimilation and conductance but higher A/g than for the other species. In contrast to the glasshouse results, the three pasture species had similar Δ values when growing together in mixed-species swards in the field. Reasons for these differing responses between glasshouse and field-grown plants are discussed in terms of the implications for improving the transpiration efficiency of mixed-species annual pasture communities in the field.

  1. Why a regional approach to postgraduate water education makes sense - the WaterNet experience in Southern Africa

    Science.gov (United States)

    Jonker, L.; van der Zaag, P.; Gumbo, B.; Rockström, J.; Love, D.; Savenije, H. H. G.

    2012-03-01

    This paper reports the experience of a regional network of academic departments involved in water education that started as a project and evolved, over a period of 12 yr, into an independent network organisation. The paper pursues three objectives. First, it argues that it makes good sense to organise postgraduate education and research on water resources on a regional scale. This is because water has a transboundary dimension that poses delicate sharing questions, an approach that promotes a common understanding of what the real water-related issues are, results in future water specialists speaking a common (water) language, enhances mutual respect, and can thus be considered an investment in future peace. Second, it presents the WaterNet experience as an example that a regional approach can work and has an impact. Third, it draws three generalised lessons from the WaterNet experience. Lesson 1: For a regional capacity building network to be effective, it must have a legitimate ownership structure and a clear mandate. Lesson 2: Organising water-related training opportunities at a regional and transboundary scale makes sense - not only because knowledge resources are scattered, but also because the topic - water - has a regional and transboundary scope. Lesson 3: Jointly developing educational programmes by sharing expertise and resources requires intense intellectual management and sufficient financial means.

  2. 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.

  3. Surface Acoustic Waves to Drive Plant Transpiration.

    Science.gov (United States)

    Gomez, Eliot F; Berggren, Magnus; Simon, Daniel T

    2017-03-31

    Emerging fields of research in electronic plants (e-plants) and agro-nanotechnology seek to create more advanced control of plants and their products. Electronic/nanotechnology plant systems strive to seamlessly monitor, harvest, or deliver chemical signals to sense or regulate plant physiology in a controlled manner. Since the plant vascular system (xylem/phloem) is the primary pathway used to transport water, nutrients, and chemical signals-as well as the primary vehicle for current e-plant and phtyo-nanotechnology work-we seek to directly control fluid transport in plants using external energy. Surface acoustic waves generated from piezoelectric substrates were directly coupled into rose leaves, thereby causing water to rapidly evaporate in a highly localized manner only at the site in contact with the actuator. From fluorescent imaging, we find that the technique reliably delivers up to 6x more water/solute to the site actuated by acoustic energy as compared to normal plant transpiration rates and 2x more than heat-assisted evaporation. The technique of increasing natural plant transpiration through acoustic energy could be used to deliver biomolecules, agrochemicals, or future electronic materials at high spatiotemporal resolution to targeted areas in the plant; providing better interaction with plant physiology or to realize more sophisticated cyborg systems.

  4. Catch me if you can: Comparing ballast water sampling skids to traditional net sampling

    Science.gov (United States)

    Bradie, Johanna; Gianoli, Claudio; Linley, Robert Dallas; Schillak, Lothar; Schneider, Gerd; Stehouwer, Peter; Bailey, Sarah

    2018-03-01

    With the recent ratification of the International Convention for the Control and Management of Ships' Ballast Water and Sediments, 2004, it will soon be necessary to assess ships for compliance with ballast water discharge standards. Sampling skids that allow the efficient collection of ballast water samples in a compact space have been developed for this purpose. We ran 22 trials on board the RV Meteor from June 4-15, 2015 to evaluate the performance of three ballast water sampling devices (traditional plankton net, Triton sampling skid, SGS sampling skid) for three organism size classes: ≥ 50 μm, ≥ 10 μm to Natural sea water was run through the ballast water system and untreated samples were collected using paired sampling devices. Collected samples were analyzed in parallel by multiple analysts using several different analytic methods to quantify organism concentrations. To determine whether there were differences in the number of viable organisms collected across sampling devices, results were standardized and statistically treated to filter out other sources of variability, resulting in an outcome variable representing the mean difference in measurements that can be attributed to sampling devices. These results were tested for significance using pairwise Tukey contrasts. Differences in organism concentrations were found in 50% of comparisons between sampling skids and the plankton net for ≥ 50 μm, and ≥ 10 μm to < 50 μm size classes, with net samples containing either higher or lower densities. There were no differences for < 10 μm organisms. Future work will be required to explicitly examine the potential effects of flow velocity, sampling duration, sampled volume, and organism concentrations on sampling device performance.

  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 influence of fish culture in floating net cages on microbial indicators of water quality

    Directory of Open Access Journals (Sweden)

    K. Gorlach-Lira

    Full Text Available This work was carried out to analyse the microbiological parameters of the water quality of a reservoir used for the irrigation and culture of tilapia (Oreochromis niloticus in floating net cages. The physico-chemical parameters, counts of mesophilic total aerobic bacteria, total and thermotolerant coliforms and fecal streptococci, and the presence of Escherichia coli in samples of water collected in three sites of the reservoir (pre-culture site, culture site, post-culture site were analysed. The levels of ammonia (0.047-0.059 mg/L, nitrite (0.001-0.021 mg/L and total phosphorus (0.050-0.355 mg/L in the water did not show significant differences (p > 0.05 between sampling sites. The levels of total bacteria in the water varied between 1.3 x 104 and 67.3 x 104 CFU/100 mL. The MPN values of thermotolerant coliforms (< 930 MPN/100 mL were within values recommended for water used for fish culture and/or irrigation. The presence of E. coli and fecal streptococci were verified in 48% and 56% of analysed samples, respectively. The site with floating net cages showed more samples contaminated with E. coli and fecal streptococci than other sampling points.

  7. Net carbon allocation in soybean seedlings as influenced by soil water stress at two soil temperatures

    International Nuclear Information System (INIS)

    McCoy, E.L.; Boersma, L.; Ekasingh, M.

    1990-01-01

    The influence of water stress at two soil temperatures on allocation of net photoassimilated carbon in soybean (Glycine max [L.] Merr.) was investigated using compartmental analysis. The experimental phase employed classical 14 C labeling methodology with plants equilibrated at soil water potentials of -0.04, -0.25 and -0.50 MPa; and soil temperatures of 25 and 10C. Carbon immobilization in the shoot apex generally followed leaf elongation rates with decreases in both parameters at increasing water stress at both soil temperatures. However, where moderate water stress resulted in dramatic declines in leaf elongation rates, carbon immobilization rates were sharply decreased only at severe water stress levels. Carbon immobilization was decreased in the roots and nodules of the nonwater stressed treatment by the lower soil temperature. This relation was reversed with severe water stress, and carbon immobilization in the roots and nodules was increased at the lower soil temperature. Apparently, the increased demand for growth and/or carbon storage in these tissues with increased water stress overcame the low soil temperature limitations. Both carbon pool sizes and partitioning of carbon to the sink tissues increased with moderate water stress at 25C soil temperature. Increased pool sizes were consistent with whole plant osmotic adjustment at moderate water stress. Increased partitioning to the sinks was consistent with carbon translocation processes being less severely influenced by water stress than is photosynthesis

  8. Net Zero Fort Carson: Integrating Energy, Water, and Waste Strategies to Lower the Environmental Impact of a Military Base

    Science.gov (United States)

    Military bases resemble small cities and face similar sustainability challenges. As pilot studies in the U.S. Army Net Zero program, 17 locations are moving to 100% renewable energy, zero depletion of water resources, and/or zero waste to landfill by 2020. Some bases target net z...

  9. 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

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

    Science.gov (United States)

    Hebbern, Christopher A; Laursen, Kristian Holst; Ladegaard, Anne H; Schmidt, Sidsel B; Pedas, Pai; Bruhn, Dan; Schjoerring, Jan K; Wulfsohn, Dvoralai; Husted, Søren

    2009-03-01

    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 revealed that the quantum yield efficiency of PSII (F(v)/F(m)) was reduced from 0.83 in Mn-sufficient control plants to below 0.5 in Mn-starved plants. Leaf Mn concentrations declined from 30 to 7 microg Mn g(-1) dry weight in control and Mn-starved plants, respectively. Mn-starved plants had up to four-fold higher transpiration than control plants. Stomatal closure and opening upon light/dark transitions took place at the same rate in both Mn treatments, but the nocturnal leaf conductance for water vapour was still twice as high in Mn-starved plants compared with the control. The observed increase in transpiration was substantiated by (13)C-isotope discrimination analysis and gravimetric measurement of the water consumption, showing significantly lower water use efficiency in Mn-starved plants. The extractable wax content of leaves of Mn-starved plants was approximately 40% lower than that in control plants, and it is concluded that the increased leaf conductance and higher transpirational water loss are correlated with a reduction in the epicuticular wax layer under Mn deficiency.

  11. Urban net-zero water treatment and mineralization: experiments, modeling and design.

    Science.gov (United States)

    Englehardt, James D; Wu, Tingting; Tchobanoglous, George

    2013-09-01

    Water and wastewater treatment and conveyance account for approximately 4% of US electric consumption, with 80% used for conveyance. Net zero water (NZW) buildings would alleviate demands for a portion of this energy, for water, and for the treatment of drinking water for pesticides and toxic chemical releases in source water. However, domestic wastewater contains nitrogen loads much greater than urban/suburban ecosystems can typically absorb. The purpose of this work was to identify a first design of a denitrifying urban NZW treatment process, operating at ambient temperature and pressure and circum-neutral pH, and providing mineralization of pharmaceuticals (not easily regulated in terms of environmental half-life), based on laboratory tests and mass balance and kinetic modeling. The proposed treatment process is comprised of membrane bioreactor, iron-mediated aeration (IMA, reported previously), vacuum ultrafiltration, and peroxone advanced oxidation, with minor rainwater make-up and H2O2 disinfection residual. Similar to biological systems, minerals accumulate subject to precipitative removal by IMA, salt-free treatment, and minor dilution. Based on laboratory and modeling results, the system can produce potable water with moderate mineral content from commingled domestic wastewater and 10-20% rainwater make-up, under ambient conditions at individual buildings, while denitrifying and reducing chemical oxygen demand to below detection (<3 mg/L). While economics appear competitive, further development and study of steady-state concentrations and sludge management options are needed. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. 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

  13. Effects of salt and water stress on plant biomass and photosynthetic ...

    African Journals Online (AJOL)

    Water deficit led to earlier peaks of net photosynthetic rate (PN) during the day. Relative rate of electron transport (ETR) decreased, but optimal quantum yield of photosystem II (Fv/Fm) showed no significant difference (P<0.05) with water deficit (from 60 to 20% FC); soil salt significantly decreased PN and transpiration rate ...

  14. 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.

  15. On the extent of genetic variation for transpiration efficiency in sorghum

    International Nuclear Information System (INIS)

    Hammer, G.L.; Broad, I.J.; Farquhar, G.D.

    1997-01-01

    A glasshouse study examined 49 diverse sorghum lines for variation in transpiration efficiency. Three of the 49 lines grown were Sorghum spp. native to Australia; one was the major weed Johnson grass (Sorghum halepense), and the remaining 45 lines were cultivars of Sorghum bicolor. All plants were grown under non-limiting water and nutrient conditions using a semi-automatic pot watering system designed to facilitate accurate measurement of water use. Plants were harvested 56-58 days after sowing and dry weights of plant parts were determined. Transpiration efficiency differed significantly among cultivars. The 3 Australian native sorghums had much lower transpiration efficiency than the other 46 cultivars, which ranged from 7.7 to 6.0 g/kg. For the 46 diverse cultivars, the ratio of range in transpiration efficiency to its l.s.d. was 2.0, which was similar to that found among more adapted cultivars in a previous study. This is a significant finding as it suggests that there is likely to be little pay-off from pursuing screening of unadapted material for increased variation in transpiration efficiency. It is necessary, however, also to examine absolute levels of transpiration efficiency to determine whether increased levels have been found. The cultivar with greatest transpiration efficiency in this study (IS9710) had a value 9% greater (P < 0.05) than the accepted standard for adapted sorghum cultivars. The potential impact of such an increase in transpiration efficiency warrants continued effort to capture it. Transpiration efficiency has been related theoretically and experimentally to the degree of carbon isotope discrimination in leaf tissue in sorghum, which thus offers a relatively simple selection index. In this study, the variation in transpiration efficiency was not related simply to carbon isotope discrimination. Significant associations of transpiration efficiency with ash content and indices of photosynthetic capacity were found. However, the

  16. Annual and Seasonal Mean Net Evaporation Rates of the Red Sea Water during Jan 1958 - Dec 2007

    OpenAIRE

    Nassir, Sahbaldeen Abdulaziz

    2012-01-01

    Data set including sea level, temperature, salinity, and current from Simple Ocean Data Assimilation (SODA) is used in this study to estimate the mean net annually and seasonally evaporation rates. Then wind data is used to examine its impact on the evaporation. This work calculated the seasonal and annual evaporation rates based on assumption of that there is no net mass transport (balanced). Hence, the difference in the transport supposed to be equal to the water that has eva...

  17. Uncertainty in sap flow-based transpiration due to xylem properties

    Science.gov (United States)

    Looker, N. T.; Hu, J.; Martin, J. T.; Jencso, K. G.

    2014-12-01

    Transpiration, the evaporative loss of water from plants through their stomata, is a key component of the terrestrial water balance, influencing streamflow as well as regional convective systems. From a plant physiological perspective, transpiration is both a means of avoiding destructive leaf temperatures through evaporative cooling and a consequence of water loss through stomatal uptake of carbon dioxide. Despite its hydrologic and ecological significance, transpiration remains a notoriously challenging process to measure in heterogeneous landscapes. Sap flow methods, which estimate transpiration by tracking the velocity of a heat pulse emitted into the tree sap stream, have proven effective for relating transpiration dynamics to climatic variables. To scale sap flow-based transpiration from the measured domain (often area) to the whole-tree level, researchers generally assume constancy of scale factors (e.g., wood thermal diffusivity (k), radial and azimuthal distributions of sap velocity, and conducting sapwood area (As)) through time, across space, and within species. For the widely used heat-ratio sap flow method (HRM), we assessed the sensitivity of transpiration estimates to uncertainty in k (a function of wood moisture content and density) and As. A sensitivity analysis informed by distributions of wood moisture content, wood density and As sampled across a gradient of water availability indicates that uncertainty in these variables can impart substantial error when scaling sap flow measurements to the whole tree. For species with variable wood properties, the application of the HRM assuming a spatially constant k or As may systematically over- or underestimate whole-tree transpiration rates, resulting in compounded error in ecosystem-scale estimates of transpiration.

  18. Biotic, temporal and spatial variability of tritium concentrations in transpirate samples collected in the vicinity of a near-surface low-level nuclear waste disposal site and nearby research reactor

    Energy Technology Data Exchange (ETDEWEB)

    Twining, J.R., E-mail: jrt@ansto.gov.au [Institute for Environmental Research, ANSTO, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Hughes, C.E.; Harrison, J.J.; Hankin, S.; Crawford, J.; Johansen, M.; Dyer, L. [Institute for Environmental Research, ANSTO, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)

    2011-06-15

    The results of a 21 month sampling program measuring tritium in tree transpirate with respect to local sources are reported. The aim was to assess the potential of tree transpirate to indicate the presence of sub-surface seepage plumes. Transpirate gathered from trees near low-level nuclear waste disposal trenches contained activity concentrations of {sup 3}H that were significantly higher (up to {approx}700 Bq L{sup -1}) than local background levels (0-10 Bq L{sup -1}). The effects of the waste source declined rapidly with distance to be at background levels within 10s of metres. A research reactor 1.6 km south of the site contributed significant (p < 0.01) local fallout {sup 3}H but its influence did not reach as far as the disposal trenches. The elevated {sup 3}H levels in transpirate were, however, substantially lower than groundwater concentrations measured across the site (ranging from 0 to 91% with a median of 2%). Temporal patterns of tree transpirate {sup 3}H, together with local meteorological observations, indicate that soil water within the active root zones comprised a mixture of seepage and rainfall infiltration. The degree of mixing was variable given that the soil water activity concentrations were heterogeneous at a scale equivalent to the effective rooting volume of the trees. In addition, water taken up by roots was not well mixed within the trees. Based on correlation modelling, net rainfall less evaporation (a surrogate for infiltration) over a period of from 2 to 3 weeks prior to sampling seems to be the optimum predictor of transpirate {sup 3}H variability for any sampled tree at this site. The results demonstrate successful use of {sup 3}H in transpirate from trees to indicate the presence and general extent of sub-surface contamination at a low-level nuclear waste site. - Highlights: > Data on environmental tritium behaviour over 21 months related to a legacy waste site are presented. > The relative contributions of atmospheric and

  19. Interactive effects of nocturnal transpiration and climate change on the root hydraulic redistribution and carbon and water budgets of southern United States pine plantations

    Science.gov (United States)

    Jean-Christophe Domec; Jérôme Ogée; Asko Noormets; Julien Jouangy; Michael Gavazzi; Emrys Treasure; Ge Sun; Steve G. McNulty; John S. King

    2012-01-01

    Deep root water uptake and hydraulic redistribution (HR) have been shown to play a major role in forest ecosystems during drought, but little is known about the impact of climate change, fertilization and soil characteristics on HR and its consequences on water and carbon fluxes. Using data from three mid-rotation loblolly pine plantations, and simulations with the...

  20. Modeling the Economic Feasibility of Large-Scale Net-Zero Water Management: A Case Study.

    Science.gov (United States)

    Guo, Tianjiao; Englehardt, James D; Fallon, Howard J

      While municipal direct potable water reuse (DPR) has been recommended for consideration by the U.S. National Research Council, it is unclear how to size new closed-loop DPR plants, termed "net-zero water (NZW) plants", to minimize cost and energy demand assuming upgradient water distribution. Based on a recent model optimizing the economics of plant scale for generalized conditions, the authors evaluated the feasibility and optimal scale of NZW plants for treatment capacity expansion in Miami-Dade County, Florida. Local data on population distribution and topography were input to compare projected costs for NZW vs the current plan. Total cost was minimized at a scale of 49 NZW plants for the service population of 671,823. Total unit cost for NZW systems, which mineralize chemical oxygen demand to below normal detection limits, is projected at ~$10.83 / 1000 gal, approximately 13% above the current plan and less than rates reported for several significant U.S. cities.

  1. Structural adjustments in resprouting trees drive differences in post-fire transpiration.

    Science.gov (United States)

    Nolan, Rachael H; Mitchell, Patrick J; Bradstock, Ross A; Lane, Patrick N J

    2014-02-01

    Following disturbance many woody species are capable of resprouting new foliage, resulting in a reduced leaf-to-sapwood area ratio and altered canopy structure. We hypothesized that such changes would promote adjustments in leaf physiology, resulting in higher rates of transpiration per unit leaf area, consistent with the mechanistic framework proposed by Whitehead et al. (Whitehead D, Jarvis PG, Waring RH (1984) Stomatal conductance, transpiration and resistance to water uptake in a Pinus sylvestris spacing experiment. Can J For Res 14:692-700). We tested this in Eucalyptus obliqua L'Hér following a wildfire by comparing trees with unburnt canopies with trees that had been subject to 100% canopy scorch and were recovering their leaf area via resprouting. In resprouting trees, foliage was distributed along the trunk and on lateral branches, resulting in shorter hydraulic path lengths. We evaluated measurements of whole-tree transpiration and structural and physiological traits expected to drive any changes in transpiration. We used these structural and physiological measurements to parameterize the Whitehead et al. equation, and found that the expected ratio of transpiration per unit leaf area between resprouting and unburnt trees was 3.41. This is similar to the observed ratio of transpiration per unit leaf area, measured from sapflow observations, which was 2.89 (i.e., resprouting trees had 188% higher transpiration per unit leaf area). Foliage at low heights (tree crown (14-18 m) in a number of traits, including higher specific leaf area, midday leaf water potential and higher rates of stomatal conductance and photosynthesis. We conclude that these post-fire adjustments in resprouting trees help to drive increased stomatal conductance and hydraulic efficiency, promoting the rapid return of tree-scale transpiration towards pre-disturbance levels. These transient patterns in canopy transpiration have important implications for modelling stand-level water fluxes

  2. OUT Success Stories: Transpired Solar Collectors

    International Nuclear Information System (INIS)

    Clyne, R.

    2000-01-01

    Transpired solar collectors are a reliable, low-cost technology for preheating building ventilation air. With simple payback periods ranging from 3 to 12 years and an estimated 30-year life span, transpired collector systems offer building owners substantial cost savings

  3. Residual transpiration as a component of salinity stress tolerance mechanism: a case study for barley.

    Science.gov (United States)

    Hasanuzzaman, Md; Davies, Noel W; Shabala, Lana; Zhou, Meixue; Brodribb, Tim J; Shabala, Sergey

    2017-06-19

    While most water loss from leaf surfaces occurs via stomata, part of this loss also occurs through the leaf cuticle, even when the stomata are fully closed. This component, termed residual transpiration, dominates during the night and also becomes critical under stress conditions such as drought or salinity. Reducing residual transpiration might therefore be a potentially useful mechanism for improving plant performance when water availability is reduced (e.g. under saline or drought stress conditions). One way of reducing residual transpiration may be via increased accumulation of waxes on the surface of leaf. Residual transpiration and wax constituents may vary with leaf age and position as well as between genotypes. This study used barley genotypes contrasting in salinity stress tolerance to evaluate the contribution of residual transpiration to the overall salt tolerance, and also investigated what role cuticular waxes play in this process. Leaves of three different positions (old, intermediate and young) were used. Our results show that residual transpiration was higher in old leaves than the young flag leaves, correlated negatively with the osmolality, and was positively associated with the osmotic and leaf water potentials. Salt tolerant varieties transpired more water than the sensitive variety under normal growth conditions. Cuticular waxes on barley leaves were dominated by primary alcohols (84.7-86.9%) and also included aldehydes (8.90-10.1%), n-alkanes (1.31-1.77%), benzoate esters (0.44-0.52%), phytol related compounds (0.22-0.53%), fatty acid methyl esters (0.14-0.33%), β-diketones (0.07-0.23%) and alkylresorcinols (1.65-3.58%). A significant negative correlation was found between residual transpiration and total wax content, and residual transpiration correlated significantly with the amount of primary alcohols. Both leaf osmolality and the amount of total cuticular wax are involved in controlling cuticular water loss from barley leaves under well

  4. 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...

  5. Evaluating the Life Cycle Environmental Benefits and Trade-Offs of Water Reuse Systems for Net-Zero Buildings.

    Science.gov (United States)

    Hasik, Vaclav; Anderson, Naomi E; Collinge, William O; Thiel, Cassandra L; Khanna, Vikas; Wirick, Jason; Piacentini, Richard; Landis, Amy E; Bilec, Melissa M

    2017-02-07

    Aging water infrastructure and increased water scarcity have resulted in higher interest in water reuse and decentralization. Rating systems for high-performance buildings implicitly promote the use of building-scale, decentralized water supply and treatment technologies. It is important to recognize the potential benefits and trade-offs of decentralized and centralized water systems in the context of high-performance buildings. For this reason and to fill a gap in the current literature, we completed a life cycle assessment (LCA) of the decentralized water system of a high-performance, net-zero energy, net-zero water building (NZB) that received multiple green building certifications and compared the results with two modeled buildings (conventional and water efficient) using centralized water systems. We investigated the NZB's impacts over varying lifetimes, conducted a break-even analysis, and included Monte Carlo uncertainty analysis. The results show that, although the NZB performs better in most categories than the conventional building, the water efficient building generally outperforms the NZB. The lifetime of the NZB, septic tank aeration, and use of solar energy have been found to be important factors in the NZB's impacts. While these findings are specific to the case study building, location, and treatment technologies, the framework for comparison of water and wastewater impacts of various buildings can be applied during building design to aid decision making. As we design and operate high-performance buildings, the potential trade-offs of advanced decentralized water treatment systems should be considered.

  6. Progress in design and analysis of the net water cooled liquid breeder blanket

    International Nuclear Information System (INIS)

    Danner, W.; Rieger, M.; Verschuur, K.A.; Vieider, G.; Casini, G.; Chazalon, M.; Libin, B.; Farfaletti-Casali, F.; Piana, R.

    1987-01-01

    The NET liquid breeder blanket was subjected to a major design revision and integrated in the new NET-DN machine configuration. In this paper briefly the most essential design features are summarized and some results from thermohydraulics and 1D as well as 3D neutronics analyses are presented. It is concluded that the performance meets well the requirements of NET but that the concept needs substantial improvement if applied to a reactor

  7. COST-EFFECTIVE APPROACH TO ESTIMATE UNREPORTED DATA: REBUILDING HISTORY OF LIFT-NET FISHING IN KWANDANG WATERS

    Directory of Open Access Journals (Sweden)

    Andhika Prima Prasetyo

    2014-12-01

    Full Text Available This paper aims to develop cost-effective approach regarding the estimation unreported annual catch data of lift-net fishery using Google Earth imagery. Lift net fishery is one of the main fishing activities of coastal community in Kwandang Bay, it has been faced problem of uncertain fisheries status due to limited recorded data. Combination of a Monte Carlo procedure was applied by involving couple of assumptions on parameters such as estimate growth rate of the total number of lift-net per years (10%, day at sea per unit per month (21 days and operated lift-net per month (50% and 80%. The results showed that 101 units of lift-nets were found around Kwandang waters based on Google Earth imagery recorded in October, 7th 2010, and this were used as a benchmark of calculation. This prediction was 28 units higher than official data from North Gorontalo District of Marine Affairs and Fisheries Services (DKP Gorontalo Utara. Compared with capture fisheries statistics issued by Kwandang CFP, the estimated lift-net catches based on two-scenarios represent additional catches of 46 % and 86 %. These results suggested and could be used as a correction index to improve the reliability of Kwandang District officially reported fisheries statistics as a baseline to develop a local common fisheries policy.

  8. Water and energy link in the cities of the future - achieving net zero carbon and pollution emissions footprint.

    Science.gov (United States)

    Novotny, V

    2011-01-01

    This article discusses the link between water conservation, reclamation, reuse and energy use as related to the goal of achieving the net zero carbon emission footprint in future sustainable cities. It defines sustainable ecocities and outlines quantitatively steps towards the reduction of energy use due to water and used water flows, management and limits in linear and closed loop water/stormwater/wastewater management systems. The three phase water energy nexus diagram may have a minimum inflection point beyond which reduction of water demand may not result in a reduction of energy and carbon emissions. Hence, water conservation is the best alternative solution to water shortages and minimizing the carbon footprint. A marginal water/energy chart is developed and proposed to assist planners in developing future ecocities and retrofitting older communities to achieve sustainability.

  9. Uncertainty in the response of transpiration to CO2 and implications for climate change

    International Nuclear Information System (INIS)

    Mengis, N; Keller, D P; Oschlies, A; Eby, M

    2015-01-01

    While terrestrial precipitation is a societally highly relevant climate variable, there is little consensus among climate models about its projected 21st century changes. An important source of precipitable water over land is plant transpiration. Plants control transpiration by opening and closing their stomata. The sensitivity of this process to increasing CO 2 concentrations is uncertain. To assess the impact of this uncertainty on future climate, we perform experiments with an intermediate complexity Earth System Climate Model (UVic ESCM) for a range of model-imposed transpiration-sensitivities to CO 2 . Changing the sensitivity of transpiration to CO 2 causes simulated terrestrial precipitation to change by −10% to +27% by 2100 under a high emission scenario. This study emphasises the importance of an improved assessment of the dynamics of environmental impact on vegetation to better predict future changes of the terrestrial hydrological and carbon cycles. (letter)

  10. The relationship between transpiration and nutrient uptake in wheat changes under elevated atmospheric CO2.

    Science.gov (United States)

    Houshmandfar, Alireza; Fitzgerald, Glenn J; O'Leary, Garry; Tausz-Posch, Sabine; Fletcher, Andrew; Tausz, Michael

    2017-12-04

    The impact of elevated [CO 2 ] (e[CO 2 ]) on crops often includes a decrease in their nutrient concentrations where reduced transpiration-driven mass flow of nutrients has been suggested to play a role. We used two independent approaches, a free-air CO 2 enrichment (FACE) experiment in the South Eastern wheat belt of Australia and a simulation study employing the agricultural production systems simulator (APSIM), to show that transpiration (mm) and nutrient uptake (g m -2 ) of nitrogen (N), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg) and manganese (Mn) in wheat are correlated under e[CO 2 ], but that nutrient uptake per unit water transpired is higher under e[CO 2 ] than under ambient [CO 2 ] (a[CO 2 ]). This result suggests that transpiration-driven mass flow of nutrients contributes to decreases in nutrient concentrations under e[CO 2 ], but cannot solely explain the overall decline. © 2017 Scandinavian Plant Physiology Society.

  11. Modelling the effect of low soil temperatures on transpiration by Scots pine

    Science.gov (United States)

    Mellander, Per-Erik; Stähli, Manfred; Gustafsson, David; Bishop, Kevin

    2006-06-01

    For ecosystem modelling of the Boreal forest it is important to include processes associated with low soil temperature during spring-early summer, as these affect the tree water uptake. The COUP model, a physically based SVAT model, was tested with 2 years of soil and snow physical measurements and sap flow measurements in a 70-year-old Scots pine stand in the boreal zone of northern Sweden. During the first year the extent and duration of soil frost was manipulated in the field. The model was successful in reproducing the timing of the soil warming after the snowmelt and frost thaw. A delayed soil warming, into the growing season, severely reduced the transpiration. We demonstrated the potential for considerable overestimation of transpiration by the model if the reduction of the trees' capacity to transpire due to low soil temperatures is not taken into account. We also demonstrated that the accumulated effect of aboveground conditions could be included when simulating the relationship between soil temperature and tree water uptake. This improved the estimated transpiration for the control plot and when soil warming was delayed into the growing season. The study illustrates the need of including antecedent conditions on root growth in the model in order to catch these effects on transpiration. The COUP model is a promising tool for predicting transpiration in high-latitude stands.

  12. Forest fire effects on transpiration: process modeling of sapwood area reduction

    Science.gov (United States)

    Michaletz, Sean; Johnson, Edward

    2010-05-01

    Transpiration is a hydrological process that is strongly affected by forest fires. In crown fires, canopy fine fuels (foliage, buds, and small branches) combust, which kills individual trees and stops transpiration of the entire stand. In surface fires (intensities ≤ 2500 kW m-1), however, effects on transpiration are less predictable becuase heat transfer from the passing fireline can injure or kill fine roots, leaves, and sapwood; post-fire transpiration of forest stands is thus governed by fire effects on individual tree water budgets. Here, we consider fire effects on cross-sectional sapwood area. A two-dimensional model of transient bole heating is used to estimate radial isotherms for a range of fireline intensities typical of surface fires. Isotherms are then used to drive three processes by which heat may reduce sapwood area: 1) necrosis of living cells in contact with xylem conduits, which prevents repair of natural embolism; 2) relaxation of viscoelastic conduit wall polymers (cellulose, hemicelloluse, and lignin), which reduces cross-sectional conduit area; and 3) boiling of metastable water under tension, which causes conduit embolism. Results show that these processes operate on different time scales, suggesting that fire effects on transpiration vary with time since fire. The model can be linked with a three-dimensional physical fire spread model to predict size-dependent effects on individual trees, which can be used to estimate scaling of individual tree and stand-level transpiration.

  13. 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

  14. Quantifying the Components of Evapotranspiration from Plant Communities, Soil Evaporation and Plant Transpiration, with Oxygen-18 Isotopes and Micrometeorology

    Energy Technology Data Exchange (ETDEWEB)

    Denmead, Tom [CSIRO Centre for Environmental Mechanics, GPO Box 821, Canberra, ACT 2601 (Australia); Heng, Lee; Nguyen, Long [Soil and Water Management and Crop Nutrition Section, IAEA (Austria); Zeeman, Matthias [Karlsruhe Institute of Technology, Garmisch-Partenkirchen (Germany); Mayr, Leo; Arrillaga, Jose Luis [Soil and Water Management and Crop Nutrition Laboratory, IAEA (Austria); Cepuder, Peter [Department of Water-Atmosphere-Environment, Institute for Hydraulics and Rural Water Management (BOKU), Vienna (Austria)

    2013-01-15

    The Keeling plot (Keeling, 1961) approach has been shown to provide an estimate of the relative proportions of water vapour emanating from evaporation (E) from soil, and transpiration (T) from the plant canopy (Moreira et. al., 1997; Williams et al., 2004). This estimate can be used in conjunction with measurements of the net water vapour flux and evapotranspiration (ET), to quantify the E and T components using an Inverse Lagrangian (IL) approach based on canopy turbulence (Raupach, 1989), which allows the identification of water vapour in the different canopy layers (Denmead et al., 2005). A study was carried out on a wheat crop over a 3-day period in April (daily temperatures ranged from 14-23''oC) at the BOKU experimental field outside Vienna to provide an independent check of the relative proportions of soil evaporation (E) and plant transpiration (T) estimated by the Keeling plot {sigma}{sup 18}O isotope analysis and by the application of the IL model of water vapour transport in plant canopies. The eddy covariance instrumentation to measure ET was provided by the Karlsruhe Institute of Technology at Garmisch-Partenkirchen, Germany. Transpiration rates, estimated by the {sigma}{sup 18}O isotopic technique were similar to those derived from Inverse Lagrangian analyses. indicating that the IL and isotopic analyses gave essentially the same partitioning of evapotranspiration into E and T. The use of the IL analysis to determine water vapour in different segments of the canopy is illustrated. In these observations the soil was dry (9-12 %) and soil evaporation was small. The eddy covariance approach confirmed the correctness of the IL analysis for the total water loss from the canopy (to within 6%) (data not shown). The IL and the isotopic analyses gave essentially the same partitioning of ET into E and T for 3 days on a dry soil. The isotopic analysis using {sigma}{sup 18}O gave E/ET {approx} 4% and T/ET {approx} 96%, while IL analysis gave corresponding figures

  15. Net ion fluxes in the facultative air-breather Hoplosternum littorale (tamoata) and the obligate air-breather Arapaima gigas (pirarucu) exposed to different Amazonian waters.

    Science.gov (United States)

    Baldisserotto, Bernardo; Copatti, Carlos E; Gomes, Levy C; Chagas, Edsandra C; Brinn, Richard P; Roubach, Rodrigo

    2008-12-01

    Fishes that live in the Amazon environment may be exposed to several kinds of water: black water (BW), acidic black water (pH 3.5) (ABW) and white water (WW), among others. The aim of the present study was to analyze net ion fluxes in the facultative air-breather Hoplosternum littorale (tamoata) and the obligate air-breather Arapaima gigas (pirarucu) exposed to different types of water. Fishes were acclimated in well water and later placed in individual chambers containing one type of water for ion flux measurements. After 4 h, the water in the chambers was replaced by a different type of water. The transfer of both species to ABW (independent of previous water exposure) increased net ion loss. Tamoatas transferred from ABW to BW or WW presented a net ion influx, but pirarucus showed only small changes on net ion efflux. These results allow us to conclude that tamoatas and pirarucus present differences in terms of ion regulation but that the general aspects of the ion flux are similar: (1) exposure to ABW led to net ion loss; (2) transfer from BW to WW or vice-versa induced only minor changes on net ion fluxes. These observations demonstrate that any osmoregulatory difficulties encountered by either species during changes between these latter two waters can be easily overcome.

  16. Mapping dry-season tree transpiration of an oak woodland at the catchment scale, using object-attributes derived from satellite imagery and sap flow measurements

    NARCIS (Netherlands)

    Reyes-Acosta, J.L.; Lubczynski, M.

    2013-01-01

    Tree transpiration is an important plant-physiological process that influences the water cycle, thereby influencing ecosystems and even the quantity of available water resources. However, direct tree-transpiration measurements, particularly at large spatial scales, are still rare, due to the

  17. Near-optimal response of instantaneous transpiration efficiency to vapour pressure deficit, temperature and [CO2] in cotton (Gossypium hirsutum L.).

    Science.gov (United States)

    The instantaneous transpiration efficiency (ITE, the ratio of photosynthesis rate to transpiration) is an important variable for crops, because it ultimately affects dry mass production per unit of plant water lost to the atmosphere. The theory that stomata optimize carbon uptake per unit water used...

  18. 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

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

    Science.gov (United States)

    Medina, Susan; Gupta, S K; Vadez, Vincent

    2017-01-01

    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 F 1 -hybrids, 18 F 1 -hybrids and then 40 F 1 -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

  20. 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

    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......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.......5-1.3 kPa on transpiration and stomatal conductance (gs ) of tree seedlings in the temperate forest understory (Duke Forest, North Carolina, USA). We observed peaked responses of transpiration to VPD in all seedlings, and the optimum VPD for transpiration (Dopt ) shifted proportionally with increasing...

  1. Growth CO{sub 2} concentration modifies the transpiration response of Populus deltoides to drought and vapor pressure deficit

    Energy Technology Data Exchange (ETDEWEB)

    Engel, V. C. [South Florida Natural Resources Center, Everglades National Park, Homestead, FL (United States); Griffin, K. L. [Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY (United States); Murthy, R.; Patterson, L.; Klimas, C. [Columbia University, Biosphere 2 Center, Oracle, AZ (United States); Potosnak, M. [National Center for Atmospheric Research, Boulder, CO (United States)

    2004-10-01

    To gain a better understanding of the hydraulic constraints on transpiration, altered canopy water relations in response to elevated carbon dioxide was evaluated in a morphological context. It was expected that by integrating the information gained into predictive models of canopy water balance in elevated carbon dioxide, our understanding of leaf-level responses to drought stresses and evaporative demand will also improve. To achieve these objectives, transpiration rates and leaf-to-sapwood area ratios in clonal stands of cottonwoods grown in near-ambient and elevated carbon dioxide were measured at the Biosphere 2 facility near Oracle, Arizona. Results were interpreted in terms of physical controls versus the direct and indirect effects of growth mediated by morphological changes on transpiration fluxes during periods of drought and high evaporative demand. Leaf-level transpiration rates were found to be nearly equivalent across carbon dioxide treatments when soil water was not limited. However, during drought stress, canopy-level transpiration was roughly equivalent across carbon dioxide treatments, but leaf-level fluxes were reduced in elevated carbon dioxide by a factor equal to the leaf area ratio of the canopies. This shift from equivalent leaf-level transpiration to equivalent canopy-level transpiration with increasing drought stress is taken to mean that maximum water use rates are controlled by atmospheric demand at high soil water content and by soil water availability at low soil water content. Changes in vapor pressure deficits had less pronounced effect on transpiration than changes in soil water content. 37 refs., 3 tabs., 5 figs.

  2. Growth CO2 concentration modifies the transpiration response of Populus deltoides to drought and vapor pressure deficit

    International Nuclear Information System (INIS)

    Engel, V. C.; Griffin, K. L.; Murthy, R.; Patterson, L.; Klimas, C.; Potosnak, M.

    2004-01-01

    To gain a better understanding of the hydraulic constraints on transpiration, altered canopy water relations in response to elevated carbon dioxide was evaluated in a morphological context. It was expected that by integrating the information gained into predictive models of canopy water balance in elevated carbon dioxide, our understanding of leaf-level responses to drought stresses and evaporative demand will also improve. To achieve these objectives, transpiration rates and leaf-to-sapwood area ratios in clonal stands of cottonwoods grown in near-ambient and elevated carbon dioxide were measured at the Biosphere 2 facility near Oracle, Arizona. Results were interpreted in terms of physical controls versus the direct and indirect effects of growth mediated by morphological changes on transpiration fluxes during periods of drought and high evaporative demand. Leaf-level transpiration rates were found to be nearly equivalent across carbon dioxide treatments when soil water was not limited. However, during drought stress, canopy-level transpiration was roughly equivalent across carbon dioxide treatments, but leaf-level fluxes were reduced in elevated carbon dioxide by a factor equal to the leaf area ratio of the canopies. This shift from equivalent leaf-level transpiration to equivalent canopy-level transpiration with increasing drought stress is taken to mean that maximum water use rates are controlled by atmospheric demand at high soil water content and by soil water availability at low soil water content. Changes in vapor pressure deficits had less pronounced effect on transpiration than changes in soil water content. 37 refs., 3 tabs., 5 figs

  3. The transient transpiration heat flux meter

    International Nuclear Information System (INIS)

    Martins, N.; Calisto, H.; Afgan, N.; Leontiev, A.I.

    2006-01-01

    A new heat flux measurement principle, based on the transient response of a transpiration radiometer, is proposed. The measurement principle of current transpiration radiometers is based on a steady-state temperature measurement in a porous element. Since it may typically take several seconds to reach these conditions, there are obvious benefits in reducing the instrument response time. This can be achieved through the analysis of its transient response in order to predict the incident heat flux. In addition, the proposed methodology enables the separate measurement of the radiative and convective components of incident heat fluxes, without compromising the known advantages of transpiration radiometers. The availability of such an instrument may enable the development of advanced monitoring, diagnostic and control systems for thermal equipment

  4. [Photosynthesis and transpiration characteristics of female and male Trichosanthes kirilowii Maxim individuals].

    Science.gov (United States)

    Liu, Yun; Zhong, Zhang-cheng; Wang, Xiao-xue; Xie, Jun; Yang, Wen-ying

    2011-03-01

    A field research was conducted on the photosynthesis and transpiration characteristics of dioecious Trichosanthes kirilowii individuals at four key development stages. At vegetative growth stage, the photosynthesis rate, transpiration rate, stomatal conductance, and water use efficiency of male individuals were higher than those of female individuals, and hence, male individuals entered into reproductive growth stage 22 days earlier than female individuals. After entering into reproductive growth stage, male individuals had higher photosynthesis rate, transpiration rate, and stomatal conductance, but slightly lower water use efficiency than female individuals. As the female individuals started to reproductive growth, their photosynthesis rate and water use efficiency were significantly lower, while the transpiration rate and stomatal conductance were higher than those of the male individuals. The effects of climate factors on the growth and development of T. kirilowii mainly occurred at its vegetative growth and early reproductive growth stages, and weakened at later reproductive growth stages. Higher temperature and lower relative humidity benefited the growth and development of T. kirilowii, and illumination could enhance the photosynthesis rate of T. kirilowii, especially its male individuals. After entering into reproductive growth stage, the photosynthesis rate of male individuals increased significantly with increasing illumination, but that of female individuals only had a slight increase, and the transpiration rate of male individuals as well as the photosynthesis rate of female individuals all increased significantly with increasing temperature.

  5. Gas-exchange, water use efficiency and yield responses of elite potato (Solanum tuberosum L.) cultivars to changes in atmospheric carbon dioxide concentration, temperature and relative humidity

    DEFF Research Database (Denmark)

    Kaminski, Kacper Piotr; Sørensen, Kirsten Kørup; Nielsen, Kåre Lehmann

    2014-01-01

    photosynthetic water use efficiency (pWUE) by stimulation in net photosynthesis rate (62% and 43% increase of An) with coincident decline in both stomatal conductance (21% and 43% decrease of gs) and leaf transpiration rate (19% and 40% decrease of E) resulting in pWUE increments of 89% and 147%. Furthermore...

  6. 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 transpiration is likely to increase significantly at the three shallowest DGW sites. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Arius kesslerl & Sciadeops troschelii (Pisces: Ariidae growth in floating net cages in estuarine waters of Buenventura Bay-Colombia

    Directory of Open Access Journals (Sweden)

    Efraín Alfonso Rubio

    1999-07-01

    Full Text Available Two species of estuary catfish the Arius kessleri (CoCoCo and the Sciadeops troschelii (Nato were held in floating net cages at varying densities in estuarine waters of Buenventura Bay-Colombia. After 120 days for the Cococo had weights of 84.1 g Y64 g with densities of 5 and 30 specimen/rn'. The growth average was 0.58-0.39 g/day; the net yield obtained vary from 0.35 to 1.16 Kg/m', the food conversion ratio vary from 3.3 to 5.0 and de survival rate vary from 86% to 100%. With the Nato we obtained weights of 164 and 184 g, beginning with weights of 41 and 108 g their growth average vary from 0.50 to 0.82 g/day. The net yield obtained vary from 0.58 to 0.75 Kg/m' and the survival rate vary from 83% to 100%. From these results we conclude that the two species of catfish studied are strong species but they do not offer good possibilities for fish farming in estuarine waters.

  8. Water, bound and mobile

    Science.gov (United States)

    Resolving the global transpiration flux is critical to constraining global carbon cycle models because carbon uptake by photosynthesis in terrestrial plants (Gross Primary Productivity, GPP) is directly related to water lost through transpiration. Quantifying GPP globally is cha...

  9. 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

    , during the snowmelt period, Ts across multiple depths was the primary control on the sap flux rate (R2 ≈ 0.7). During the dry and monsoon periods only net radiation (Rn) was found to be a driver of the flux rate (R2 ≈ 0.4). For JRB spruce, a combination of Ts across multiple depths as well as air temperature (R2 ≈ 0.5) were the dominant drivers of sap flux rate during the snowmelt period. During the monsoon period, Rn (R2 ≈ 0.4) was the dominant driver. For SCM maple, during the dry period, θ across multiple depths was the primary driver of the sap flux rate (R2 ≈ 0.8); the strength of the correlation with the control of θ on sap flux rate drastically dropping (R2 ≈ 0.2) during the monsoon period. For SCM white fir, θ across multiple depths was a weak driver of sap flux rate during the dry (R2 ≈ 0.1) and monsoon periods (R2 ≈ 0.2). This study highlights the importance of species-specific information for understanding the role of transpiration in critical zone processes. Specifically, unique environmental drivers that vary throughout the year for different vegetation types complicate the assessment of both catchment-scale water and carbon balances and for understanding of the processes that govern the complex dynamics across the CZ.

  10. A New Method to Quantify the Isotopic Signature of Leaf Transpiration: Implications for Landscape-Scale Evapotranspiration Partitioning Studies

    Science.gov (United States)

    Wang, L.; Good, S. P.; Caylor, K. K.

    2010-12-01

    Characterizing the constituent components of evapotranspiration is crucial to better understand ecosystem-level water budgets and water use dynamics. Isotope based evapotranspiration partitioning methods are promising but their utility lies in the accurate estimation of the isotopic composition of underlying transpiration and evaporation. Here we report a new method to quantify the isotopic signature of leaf transpiration under field conditions. This method utilizes a commercially available laser-based isotope analyzer and a transparent leaf chamber, modified from Licor conifer leaf chamber. The method is based on the water mass balance in ambient air and leaf transpired air. We verified the method using “artificial leaves” and glassline extracted samples. The method provides a new and direct way to estimate leaf transpiration isotopic signatures and it has wide applications in ecology, hydrology and plant physiology.

  11. Sapflow-Based Stand Transpiration in a Semiarid Natural Oak Forest on China’s Loess Plateau

    Directory of Open Access Journals (Sweden)

    Mei-Jie Yan

    2016-10-01

    Full Text Available The semi-arid region of China’s Loess Plateau is characterized by fragile ecosystems and a shortage of water resources. The major natural forest type in this region is the secondary forest with the flora dominated by the Liaodong oak (Quercus liaotungensis Koidz.. To understand its transpiration water use in relation to environmental factors, we applied Granier-type thermal dissipation probes to monitor stem sap flows of 21 sample trees, representing different classes of diameter at breast height in a permanent plot. The stem- and stand-scale transpiration values during the 2008–2010 growing seasons were estimated using measurements of sap flux densities and corresponding sapwood areas. The dominant factors affecting stand-scale transpiration varied with time scales. Daily stand transpiration correlated with daily solar radiation and daytime average vapor pressure deficit. Seasonal and interannual changes in stand transpiration were closely related to leaf area index (LAI values. No obvious relationship was observed between monthly stand transpiration and soil moisture or precipitation during the period, probably as a result of both the hysteretic effect of precipitation on transpiration, and changes in LAI throughout the growing season. Stand transpiration during the three growing seasons ranged from 75 to 106 mm, representing low to normal values for the semi-arid forest. The proportion of transpiration by oak trees in the stand was stable ranging from 60% to 66% and corresponded to their basal area proportion of approximately 59%. The results suggest that the natural forest consisting mainly of oak trees is in a formal stage of forest development that maintains a normal magnitude of annual water consumption.

  12. Net ecosystem exchange of carbon dioxide and water of far eastern Siberian Larch (Larix cajanderii on permafrost

    Directory of Open Access Journals (Sweden)

    A. J. Dolman

    2004-01-01

    Full Text Available Observations of the net ecosystem exchange of water and CO2 were made during two seasons in 2000 and 2001 above a Larch forest in Far East Siberia (Yakutsk. The measurements were obtained by eddy correlation. There is a very sharply pronounced growing season of 100 days when the forest is leaved. Maximum half hourly uptake rates are 18 µmol m-2 s-1; maximum respiration rates are 5 µmol m-2 s-1. Net annual sequestration of carbon was estimated at 160 gCm-2 in 2001. Applying no correction for low friction velocities added 60 g C m-2. The net carbon exchange of the forest was extremely sensitive to small changes in weather that may switch the forest easily from a sink to a source, even in summer. June was the month with highest uptake in 2001. The average evaporation rate of the forest approached 1.46 mm day-1 during the growing season, with peak values of 3 mm day-1 with an estimated annual evaporation of 213 mm, closely approaching the average annual rainfall amount. 2001 was a drier year than 2000 and this is reflected in lower evaporation rates in 2001 than in 2000. The surface conductance of the forest shows a marked response to increasing atmospheric humidity deficits. This affects the CO2 uptake and evaporation in a different manner, with the CO2 uptake being more affected. There appears to be no change in the relation between surface conductance and net ecosystem uptake normalized by the atmospheric humidity deficit at the monthly time scale. The response to atmospheric humidity deficit is an efficient mechanism to prevent severe water loss during the short intense growing season. The associated cost to the sequestration of carbon may be another explanation for the slow growth of these forests in this environment.

  13. Application of the Forhyd model to simulate net precipitation and intercepted water evaporation in forest canopies in Colombian amazonia

    International Nuclear Information System (INIS)

    Tellez Guio, Patricia; Boschell Villamarin, Francisco; Tobon Marin, Conrado

    2005-01-01

    Hydrologic simulation is a technique, which allows us to understand the relationships among hydrological, biological and ecological variables in an ecosystem. In this research, the FORHYD model is used to simulate the net precipitation and the water intercepted by the canopies of a mature forest, a 30-year old secondary forest, an 18-year old secondary forest, a 5-year old secondary forest, and a shifting cultivation plot, all located in Colombia's amazonia. The model calculates the water budget of the canopy by using the precipitation rates, canopy drainage and evaporation of the water intercepted by the canopy. This paper is the second one in a series of papers reporting the results of the research on the simulation of the hydrological fluxes in three different land use types of Colombian amazonia. The research was carried out in middle Caqueta of Colombian amazonia (northwest amazon basin). The FORHYD model was calibrated and validated by using field observations of the climate, net precipitation (PT), thoughtful (TH) and stem flow (ST), which were monitored during a period of 15 months from March 2001 to June 2002. These observations were used as both input variables and diagnostic variables to probe the model's precision to simulate field observations. Results showed that FORHYD simulates with a good precision the net precipitation and the evaporation of the water intercepted by the canopy. However, the model's precision depends on a good parameterization, which in turn depends on a good database of field observations. The model is a good tool for simulating the hydrological cycle and can be used to simulate critical scenarios of climate variability

  14. Experimental investigation of biomimetic self-pumping and self-adaptive transpiration cooling.

    Science.gov (United States)

    Jiang, Pei-Xue; Huang, Gan; Zhu, Yinhai; Xu, Ruina; Liao, Zhiyuan; Lu, Taojie

    2017-09-01

    Transpiration cooling is an effective way to protect high heat flux walls. However, the pumps for the transpiration cooling system make the system more complex and increase the load, which is a huge challenge for practical applications. A biomimetic self-pumping transpiration cooling system was developed inspired by the process of trees transpiration that has no pumps. An experimental investigation showed that the water coolant automatically flowed from the water tank to the hot surface with a height difference of 80 mm without any pumps. A self-adaptive transpiration cooling system was then developed based on this mechanism. The system effectively cooled the hot surface with the surface temperature kept to about 373 K when the heating flame temperature was 1639 K and the heat flux was about 0.42 MW m -2 . The cooling efficiency reached 94.5%. The coolant mass flow rate adaptively increased with increasing flame heat flux from 0.24 MW m -2 to 0.42 MW m -2 while the cooled surface temperature stayed around 373 K. Schlieren pictures showed a protective steam layer on the hot surface which blocked the flame heat flux to the hot surface. The protective steam layer thickness also increased with increasing heat flux.

  15. Zooplankton and other data collected from net casts in Coastal Waters of California from T-441; 19 April 1967 to 13 September 1967 (NODC Accession 7101507)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton and other data were collected using net casts from T-441 in the Coastal Waters of California. Data were collected from 19 April 1967 to 13 September 1967...

  16. Improvements to water use and water stress estimates with the addition of IR and net radiometers to weather stations

    Science.gov (United States)

    Evapotranspiration (ET) is often estimated with the Penman-Monteith (P-M) equation. Net radiation (Rn) is a major component of the surface energy balance and an input to the P-M equation, but it is challenging and expensive to measure accurately. For these reasons, most weather stations do not inclu...

  17. Hydrogen Economy Model for Nearly Net-Zero Cities with Exergy Rationale and Energy-Water Nexus

    Directory of Open Access Journals (Sweden)

    Birol Kılkış

    2018-05-01

    Full Text Available The energy base of urban settlements requires greater integration of renewable energy sources. This study presents a “hydrogen city” model with two cycles at the district and building levels. The main cycle comprises of hydrogen gas production, hydrogen storage, and a hydrogen distribution network. The electrolysis of water is based on surplus power from wind turbines and third-generation solar photovoltaic thermal panels. Hydrogen is then used in central fuel cells to meet the power demand of urban infrastructure. Hydrogen-enriched biogas that is generated from city wastes supplements this approach. The second cycle is the hydrogen flow in each low-exergy building that is connected to the hydrogen distribution network to supply domestic fuel cells. Make-up water for fuel cells includes treated wastewater to complete an energy-water nexus. The analyses are supported by exergy-based evaluation metrics. The Rational Exergy Management Efficiency of the hydrogen city model can reach 0.80, which is above the value of conventional district energy systems, and represents related advantages for CO2 emission reductions. The option of incorporating low-enthalpy geothermal energy resources at about 80 °C to support the model is evaluated. The hydrogen city model is applied to a new settlement area with an expected 200,000 inhabitants to find that the proposed model can enable a nearly net-zero exergy district status. The results have implications for settlements using hydrogen energy towards meeting net-zero targets.

  18. Estimating net rainfall, evaporation and water storage of a bare soil from sequential L-band emissivities

    Science.gov (United States)

    Stroosnijder, L.; Lascano, R. J.; Newton, R. W.; Vanbavel, C. H. M.

    1984-01-01

    A general method to use a time series of L-band emissivities as an input to a hydrological model for continuously monitoring the net rainfall and evaporation as well as the water content over the entire soil profile is proposed. The model requires a sufficiently accurate and general relation between soil emissivity and surface moisture content. A model which requires the soil hydraulic properties as an additional input, but does not need any weather data was developed. The method is shown to be numerically consistent.

  19. The Influence of CO2 Enrichment on Net Photosynthesis of Seagrass Zostera marina in a Brackish Water Environment

    OpenAIRE

    Pajusalu, Liina; Martin, Georg; Põllumäe, Arno; Paalme, Tiina

    2016-01-01

    Seagrasses are distributed across the globe and their communities may play key roles in the coastal ecosystems. Seagrass meadows are expected to benefit from the increased carbon availability which might be used in photosynthesis in a future high CO2 world. The main aim of this study was to examine the effect of elevated pCO2 on the net photosynthesis of seagrass Zostera marina in a brackish water environment. The short-term mesocosm experiments were conducted in Kõiguste Bay (northern part o...

  20. Effect of river discharge and geometry on tides and net water transport in an estuarine network, an idealized model applied to the Yangtze Estuary

    NARCIS (Netherlands)

    Alebregtse, N. C.|info:eu-repo/dai/nl/345704304; de Swart, H. E.|info:eu-repo/dai/nl/073449725

    2016-01-01

    Tidal propagation in, and division of net water transport over different channels in an estuarine network are analyzed using a newly developed idealized model. The water motion in this model is governed by the cross-sectionally averaged shallow water equations and is forced by tides at the seaward

  1. Carbon dioxide addition to coral reef waters suppresses net community calcification

    Science.gov (United States)

    Albright, Rebecca; Takeshita, Yuichiro; Koweek, David A.; Ninokawa, Aaron; Wolfe, Kennedy; Rivlin, Tanya; Nebuchina, Yana; Young, Jordan; Caldeira, Ken

    2018-03-01

    Coral reefs feed millions of people worldwide, provide coastal protection and generate billions of dollars annually in tourism revenue. The underlying architecture of a reef is a biogenic carbonate structure that accretes over many years of active biomineralization by calcifying organisms, including corals and algae. Ocean acidification poses a chronic threat to coral reefs by reducing the saturation state of the aragonite mineral of which coral skeletons are primarily composed, and lowering the concentration of carbonate ions required to maintain the carbonate reef. Reduced calcification, coupled with increased bioerosion and dissolution, may drive reefs into a state of net loss this century. Our ability to predict changes in ecosystem function and associated services ultimately hinges on our understanding of community- and ecosystem-scale responses. Past research has primarily focused on the responses of individual species rather than evaluating more complex, community-level responses. Here we use an in situ carbon dioxide enrichment experiment to quantify the net calcification response of a coral reef flat to acidification. We present an estimate of community-scale calcification sensitivity to ocean acidification that is, to our knowledge, the first to be based on a controlled experiment in the natural environment. This estimate provides evidence that near-future reductions in the aragonite saturation state will compromise the ecosystem function of coral reefs.

  2. Simulation of the chemical stage in water radiolysis with the help of Continuous Petri nets

    International Nuclear Information System (INIS)

    Barilla, J.; Lokajíček, M.V.; Pisaková, H.; Simr, P.

    2014-01-01

    The final biological effect of ionizing particles may be influenced often strongly by some chemical substances present in cells during irradiation by low-LET radiation. It may occur during the chemical stage of the given process, due to chemical reactions of radicals running in the given process. However, the whole chemical process may be hardly described sufficiently with the help of the usual approach based on the deterministic diffusion-kinetic computations and the stochastic Monte-Carlo simulations. We have proposed already earlier a model describing the processes (i.e., the combined effect of cluster diffusion and chemical reactions) running in individual radical clusters that might be responsible for corresponding damages of DNA molecules (i.e., formation of DSBs). Now a further generalization of the given model (using Continuous Petri nets) will be presented that makes it possible to characterize more detailed behavior of individual radicals in corresponding clusters, which might be useful especially for low-LET radiation when individual radical clusters meet a DNA molecule at different time intervals after their formation; the decreasing presence of individual radicals in corresponding clusters being established. In this paper we shall focus on the design of the corresponding mathematical model and its application; the comparison of corresponding results with experimental data obtained in the case of deoxygenated system will be presented. - Highlights: • Creation of the mathematical model. • Realization of the model with the help of Continuous Petri nets. • Obtain the time dependence of changes in the concentration of radicals

  3. Will intra-specific differences in transpiration efficiency in wheat be maintained in a high CO₂ world? A FACE study.

    Science.gov (United States)

    Tausz-Posch, Sabine; Norton, Robert M; Seneweera, Saman; Fitzgerald, Glenn J; Tausz, Michael

    2013-06-01

    This study evaluates whether the target breeding trait of superior leaf level transpiration efficiency is still appropriate under increasing carbon dioxide levels of a future climate using a semi-arid cropping system as a model. Specifically, we investigated whether physiological traits governing leaf level transpiration efficiency, such as net assimilation rates (A(net)), stomatal conductance (g(s)) or stomatal sensitivity were affected differently between two Triticum aestivum L. cultivars differing in transpiration efficiency (cv. Drysdale, superior; cv. Hartog, low). Plants were grown under Free Air Carbon dioxide Enrichment (FACE, approximately 550 µmol mol⁻¹ or ambient CO₂ concentrations (approximately 390 µmol mol⁻¹). Mean A(net) (approximately 15% increase) and gs (approximately 25% decrease) were less affected by elevated [CO₂] than previously found in FACE-grown wheat (approximately 25% increase and approximately 32% decrease, respectively), potentially reflecting growth in a dry-land cropping system. In contrast to previous FACE studies, analyses of the Ball et al. model revealed an elevated [CO₂] effect on the slope of the linear regression by 12% indicating a decrease in stomatal sensitivity to the combination of [CO₂], photosynthesis rate and humidity. Differences between cultivars indicated greater transpiration efficiency for Drysdale with growth under elevated [CO₂] potentially increasing the response of this trait. This knowledge adds valuable information for crop germplasm improvement for future climates. Copyright © Physiologia Plantarum 2012.

  4. Optimization of crude protein in diets for Nile tilapia reared in net pens: performance, hematology, and water quality

    Directory of Open Access Journals (Sweden)

    Débora Del Puppo

    Full Text Available ABSTRACT: Two experiments were conducted to evaluate the effects of reducing dietary crude protein (CP, based on the ideal protein concept for Nile tilapia reared in net pens. The experimental (isocaloric, isocalcium, and isophosphoric diets were formulated to contain 270, 300, 330, and 360g kg-1 CP. In experiment 1, 4320 Nile tilapia (13.5±0.82g were used to evaluate the performance and hematological parameters. The experimental design was completely randomized and the fish were distributed in 24 net pens (1.0m3, with four diets, six replicates, and 180 fishes per experimental unit. In experiment 2, 40 Nile tilapia (22.5±0.56g were used to evaluate the ammonia excretion. Fish were distributed in 40 aquaria (3.0L, with one fish per aquarium (n=10. No protein reduction effect was observed in feed intake and the hematocrit and hemoglobin values. Regarding the statistic models used in the present study, difference was observed between CP values. The optimal level estimated by the quadratic equation first interception with the linear response plateau (LRP as a response to CP changes in the diet was determined for weight gain (324.3g kg-1 and feed conversion (317.8g kg-1. After reduction in the CP levels, a linear reduction was observed in the ammonia excretion in water. Based on the ideal protein concept for Nile tilapia reared in net pens, reducing the CP levels in the diets is possible, without change in the performance and hematological parameters, and with a reduction in the levels of ammonia excretion in water, since amino acids are supplemented.

  5. Leaf water relations and net gas exchange responses of salinized Carrizo citrange seedlings during drought stress and recovery.

    Science.gov (United States)

    Pérez-Pérez, J G; Syvertsen, J P; Botía, P; García-Sánchez, F

    2007-08-01

    Since salinity and drought stress can occur together, an assessment was made of their interacting effects on leaf water relations, osmotic adjustment and net gas exchange in seedlings of the relatively chloride-sensitive Carrizo citrange, Citrus sinensis x Poncirus trifoliata. Plants were fertilized with nutrient solution with or without additional 100 mm NaCl (salt and no-salt treatments). After 7 d, half of the plants were drought stressed by withholding irrigation water for 10 d. Thus, there were four treatments: salinized and non-salinized plants under drought-stress or well-watered conditions. After the drought period, plants from all stressed treatments were re-watered with nutrient solution without salt for 8 d to study recovery. Leaf water relations, gas exchange parameters, chlorophyll fluorescence, proline, quaternary ammonium compounds and leaf and root concentrations of Cl(-) and Na(+) were measured. Salinity increased leaf Cl(-) and Na(+) concentrations and decreased osmotic potential (Psi(pi)) such that leaf relative water content (RWC) was maintained during drought stress. However, in non-salinized drought-stressed plants, osmotic adjustment did not occur and RWC decreased. The salinity-induced osmotic adjustment was not related to any accumulation of proline, quaternary ammonium compounds or soluble sugars. Net CO(2) assimilation rate (A(CO2)) was reduced in leaves from all stressed treatments but the mechanisms were different. In non-salinized drought-stressed plants, lower A(CO2) was related to low RWC, whereas in salinized plants decreased A(CO2) was related to high levels of leaf Cl(-) and Na(+). A(CO2) recovered after irrigation in all the treatments except in previously salinized drought-stressed leaves which had lower RWC and less chlorophyll but maintained high levels of Cl(-), Na(+) and quaternary ammonium compounds after recovery. High leaf levels of Cl(-) and Na(+) after recovery apparently came from the roots. Plants preconditioned by

  6. Gamma irradiation, hot water and imazalil treatments on decay organisms and physical quality of stored netted muskmelon fruit

    International Nuclear Information System (INIS)

    Lester, G.

    1989-01-01

    Nonchemical treatments of gamma irradiation (2 Kilograys) and hot water (57°C) and the fungicide imazalil (1000 ppm) were compared with and without shrink-film wrap for effects on decay and physical quality of netted muskmelon fruit stored at 4°C for 0 through 60 days. Gamma irradiation was ineffective in controlling decay and surface molds, and injurious to physical quality by decreasing firmness, increasing fresh weight loss, membrane leakage and vein track browning. Hot water treatment coupled with shrink-film wrap was effective in controlling decay activity and maintaining physical quality up to 20 days storage. Imazalil coupled with shrink-film wrap controlled the incidence and severity of decay and maintained fruit firmness, moisture loss, membrane permeability and vein track browning for almost 60 days storage. (author)

  7. Efeitos de produtos químicos na transpiração e no potencial da água de seringueira (Hevea brasiliensis Muell . Arg. cv.RRIM 600 Effects of chemicals on transpiration and water potential of rubber plant (Hevea brasiliensis Muell . Arg. cv.RRIM 600

    Directory of Open Access Journals (Sweden)

    P.R.C. Castro

    1984-01-01

    Full Text Available Um experimento foi realizado em condições de campo, em Piracicaba (SP, visando avali ar a eficiência de diferentes produtos químicos, em aplicação foliar, na taxa transpiratória e no potencial da água de folhas das plantas de seringueira (He Yea brasiliens is cv. RRIM 600 com 1,5 ano de idade. Os tratamentos utilizados foram: polissulfetc, de polietileno (Good-rite peps 0,04 %, oxietileno docosanol (Oed green 2%, caulim (silicato de aluminio 3%, e atrazine 50 ppm, alem do controle. Através do método da pesagem rápida de folhas desta cadas, com balança de torço tipo Jung, verificou-se a perda de água pelas plantas de seringueira foi restringida significativamente pelo anti-transpirante metabólico (atrazine com relação ao controle, aos formadores de filme e ao refletor. Polissulfeto de polietileno apresentou as menores amplitudes de variações na taxa respiratória. Atrazine também promoveu a manutenção do potencial da água das folhas mais alto (-7,8 bars com relação ao controle (-14,8 bars, de acordo com determinações efe tuadas através da Câmara de Scholander.This research deals with the effects of chemicals on transpiration and water potential of Hevea brasiliens is cv. RRIM 600 on plants, with 1,5 year old, under field conditions. Rubber plants were sprayed with poliethylen e polys ulfite 0,04%, oxyethylen e docosanol 2%, kaolin 3%, atrazine 50 ppm, and check. A higher efficiency again st water loss was observed for atrazine (10,9 mg water . cm-2 . min-1 in relation to check plants (14,6 mg water . cm . min-1 at the maximum transpiration rate average. Polyethylen e polysulfite presented lower amplitude variation of the transpiration rates during the measurements at the day period. Atrazine promoted the maint enance of a higher water potential (-7,8 bars compared to check treatment (-14,8 bars.

  8. Effects of thinning on transpiration by riparian buffer trees in response to advection and solar radiation

    Science.gov (United States)

    Advective energy occurring in edge environments may increase tree water use. In humid agricultural landscapes, advection-enhanced transpiration in riparian buffers may provide hydrologic regulation; however, research in humid environments is lacking. The objectives of this study were to determine ho...

  9. Effect of EC and transpiration on production of greenhouse tomato (Lycopersicon esculentum L.)

    NARCIS (Netherlands)

    Li, Y.; Stanghellini, C.; Challa, H.

    2001-01-01

    We investigated the hypothesis that manipulating water out-flow of a plant through the shoot environment (potential transpiration, ET0) in a glasshouse could modulate the effect of salinity/osmotic potential in the root environment upon yield of tomatoes. Contrasting root-zone salinity treatments

  10. Thermodynamic balance of photosynthesis and transpiration at increasing CO2 concentrations and rapid light fluctuations.

    Science.gov (United States)

    Marín, Dolores; Martín, Mercedes; Serrot, Patricia H; Sabater, Bartolomé

    2014-02-01

    Experimental and theoretical flux models have been developed to reveal the influence of sun flecks and increasing CO2 concentrations on the energy and entropy balances of the leaf. The rapid and wide range of fluctuations in light intensity under field conditions were simulated in a climatic gas exchange chamber and we determined the energy and entropy balance of the leaf based on radiation and gas exchange measurements. It was estimated that the energy of photosynthetic active radiation (PAR) accounts for half of transpiration, which is the main factor responsible for the exportation of the entropy generated in photosynthesis (Sg) out of the leaf in order to maintain functional the photosynthetic machinery. Although the response of net photosynthetic production to increasing concentrations of CO2 under fluctuating light is similar to that under continuous light, rates of transpiration respond slowly to changes of light intensity and are barely affected by the concentration of CO2 in the range of 260-495 ppm, in which net photosynthesis increases by more than 100%. The analysis of the results confirms that future increases of CO2 will improve the efficiency of the conversion of radiant energy into biomass, but will not reduce the contribution of plant transpiration to the leaf thermal balance. Copyright © 2013 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  11. 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

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

    Science.gov (United States)

    Nordey, Thibault; Léchaudel, Mathieu; Saudreau, Marc; Joas, Jacques; Génard, Michel

    2014-01-01

    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.

  13. Seasonal shift in climatic limiting factors on tree transpiration: evidence from sap flow observations at alpine treelines in southeast Tibet

    Directory of Open Access Journals (Sweden)

    Liu Xinsheng

    2016-07-01

    Full Text Available Alpine and northern treelines are primarily controlled by low temperatures. However, little is known about the impact of low soil temperature on tree transpiration at treelines. We aim to test the hypothesis that in cold-limited forests, the main limiting factors for tree transpiration switch from low soil temperature before summer solstice to atmospheric evaporative demand after summer solstice, which generally results in low transpiration in the early growing season. Sap flow, meteorological factors and predawn needle water potential were continuously monitored throughout one growing season across Smith fir (Abies georgei var. smithii and juniper (Juniperus saltuaria treelines in southeast Tibet. Sap flow started in early May and corresponded to a threshold mean air-temperature of 0 oC. Across tree species, transpiration was mainly limited by low soil temperature prior to the summer solstice but by vapor pressure deficit and solar radiation post-summer solstice, which was further confirmed on a daily scale. As a result, tree transpiration for both tree species was significantly reduced in the pre-summer solstice period as compared to post-summer solstice, resulting in a lower predawn needle water potential for Smith fir trees in the early growing season. Our data supported the hypothesis, suggesting that tree transpiration mainly responds to soil temperature variations in the early growing season. The results are important for understanding the hydrological response of cold-limited forest ecosystems to climate change.

  14. 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.

  15. Modeling of the chemical stage in water radiolysis using Petri nets

    International Nuclear Information System (INIS)

    Barilla, J; Simr, P; Lokajíček, M; Pisaková, H

    2014-01-01

    The biological effect of ionizing radiation is mediated practically always by the clusters of radicals formed by densely ionizing track ends of primary or secondary particles. In the case of low-LET radiation the direct effect may be practically neglected and the radical clusters meet a DNA molecule always some time after their formation. The corresponding damage effect (formation of DSB) depends then on the evolution running in individual clusters, being influenced by present chemical agents. Two main parallel processes influence then final effect: diffusion of corresponding radical clusters (lowering radical concentrations) and chemical reactions of all chemical substances present in the clusters. The processes running in the corresponding radical clusters will be modeled with the help of continuous Petri net, which enables us to study the concurrent influence of both the processes: lowering concentration of radicals due diffusion and due chemical reactions. The given model may be helpful especially when the effect of radicals on DSB formation (DNA damage) at the presence of different substances influencing radiobiological effect is to be studied

  16. Specific net present value: an improved method for assessing modularisation costs in water services with growing demand.

    Science.gov (United States)

    Maurer, M

    2009-05-01

    A specific net present value (SNPV) approach is introduced as a criterion in economic engineering decisions. The SNPV expresses average costs, including the growth rate and plant utilisation over the planning horizon, factors that are excluded from a standard net present value approach. The use of SNPV favours alternatives that are cheaper per service unit and are therefore closer to the costs that a user has to cover. It also shows that demand growth has a similar influence on average costs as an economy of scale. In a high growth scenario, solutions providing less idle capacity can have higher present value costs and still be economically favourable. The SNPV approach is applied in two examples to calculate acceptable additional costs for modularisation and comparable costs for on-site treatment (OST) as an extreme form of modularisation. The calculations show that: (i) the SNPV approach is suitable for quantifying the comparable costs of an OST system in a different scenario; (ii) small systems with projected high demand growth rates and high real interest rates are the most probable entry market for OST water treatment systems; (iii) operating expenses are currently the main economic weakness of membrane-based wastewater OST systems; and (iv) when high growth in demand is expected, up to 100% can be additionally invested in modularisation and staging the expansion of a treatment plant.

  17. 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

  18. Net removal of dissolved organic carbon in the anoxic waters of the Black Sea

    NARCIS (Netherlands)

    Margolin, A.R.; Gerringa, L.J.A.; Hansell, D.A.; Rijkenberg, M.J.A.

    2016-01-01

    Dissolved organic carbon (DOC) concentrations in the deep Black Sea are ~2.5 times higher than found in the globalocean. The two major external sources of DOC are rivers and the Sea of Marmara, a transit point for waters from theMediterranean Sea. In addition, expansive phytoplankton blooms

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

    Science.gov (United States)

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

    2013-01-01

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

  20. Contribution of black spruce (Picea mariana) transpiration to growing season evapotranspiration in a subarctic discontinuous permafrost peatland complex

    Science.gov (United States)

    Helbig, M.; Warren, R. K.; Pappas, C.; Sonnentag, O.; Berg, A. A.; Chasmer, L.; Baltzer, J. L.; Quinton, W. L.; Patankar, R.

    2016-12-01

    Partitioning the components of evapotranspiration (ET), evaporation and transpiration, has been increasingly important for the better understanding and modeling of carbon, water, and energy dynamics, and for reliable water resources quantification and management. However, disentangling its individual processes remains highly uncertain. Here, we quantify the contribution of black spruce transpiration, the dominant overstory, to ET of a boreal forest-wetland landscape in the southern Taiga Plains. In these ecosystems, thawing permafrost induces rapid landscape change, whereby permafrost-supported forested plateaus are transformed into bogs or fens (wetlands), resulting in tree mortality. Using historical and projected rates of forest-wetland changes, we assess how the contribution of black spruce transpiration to landscape ET might be altered with continued permafrost loss, and quantify the resulting water balance changes. We use two nested eddy covariance flux towers and a footprint model to quantify ET over the entire landscape. Sap flux density of black spruce is measured using the heat ratio method during the 2013 (n=22) and 2014 (n=3) growing seasons, and is used to estimate tree-level transpiration. Allometric relations between tree height, diameter at breast height and sapwood area are derived to upscale tree-level transpiration to overstory transpiration within the eddy covariance footprint. Black spruce transpiration accounts for <10% of total landscape ET. The largest daily contribution of overstory transpiration to landscape ET is observed shortly after the landscape becomes snow-free, continually decreasing throughout the progression of the growing season. Total transpiration is notably lower in 2014 (2.34 mm) than 2013 (2.83 mm) over the same 40-day period, corresponding to 3% of cumulative landscape ET in both years. This difference is likely due to the antecedent moisture conditions, where the 2014 growing season was proceeded by lower than average

  1. Petri Nets

    Indian Academy of Sciences (India)

    In a computer system, for example, typical discrete events ... This project brought out a series of influential reports on Petri net theory in the mid and late ... Technology became a leading centre for Petri net research and from then on, Petri nets ...

  2. Compensating effect of sap velocity for stand density leads to uniform hillslope-scale forest transpiration across a steep valley cross-section

    Science.gov (United States)

    Renner, Maik; Hassler, Sibylle; Blume, Theresa; Weiler, Markus; Hildebrandt, Anke; Guderle, Marcus; Schymanski, Stan; Kleidon, Axel

    2016-04-01

    Roberts (1983) found that forest transpiration is relatively uniform across different climatic conditions and suggested that forest transpiration is a conservative process compensating for environmental heterogeneity. Here we test this hypothesis at a steep valley cross-section composed of European Beech in the Attert basin in Luxemburg. We use sapflow, soil moisture, biometric and meteorological data from 6 sites along a transect to estimate site scale transpiration rates. Despite opposing hillslope orientation, different slope angles and forest stand structures, we estimated relatively similar transpiration responses to atmospheric demand and seasonal transpiration totals. This similarity is related to a negative correlation between sap velocity and site-average sapwood area. At the south facing sites with an old, even-aged stand structure and closed canopy layer, we observe significantly lower sap velocities but similar stand-average transpiration rates compared to the north-facing sites with open canopy structure, tall dominant trees and dense understorey. This suggests that plant hydraulic co-ordination allows for flexible responses to environmental conditions leading to similar transpiration rates close to the water and energy limits despite the apparent heterogeneity in exposition, stand density and soil moisture. References Roberts, J. (1983). Forest transpiration: A conservative hydrological process? Journal of Hydrology 66, 133-141.

  3. Rising CO2 widens the transpiration-photosynthesis optimality space

    Science.gov (United States)

    de Boer, Hugo J.; Eppinga, Maarten B.; Dekker, Stefan C.

    2016-04-01

    ). Measurements of gs and V cmax were obtained with a portable photosynthesis system. Our empirical results support the prediction that the V cmax:gs-ratio increases with higher CO2 in both Solanum genotypes. The 'dry' genotype revealed a significantly higher Huber value and lower V cmax than the 'wet' genotype at each CO2 growth level. Moreover, we found that the down-regulation of V cmax under higher CO2 was stronger in the 'dry' genotype than in the 'wet' genotype, whereas no change in the Huber value was observed between CO2 levels. Consistent with the theoretical trade-off between the resulting costs of transpiration and photosynthesis, we found that the CO2-induced increase in the V cmax:gs-ratio was stronger in the 'wet' genotype than in the 'dry' genotype. Given the divergence of V cmax:gs relationships observed, we conclude that rising atmospheric CO2 may widen the V cmax - gs optimality space available for plants to achieve an optimal trade-off between photosynthesis and transpiration. References Prentice, I. C., Dong, N., Gleason, S. M., Maire, V. and Wright, I. J.: Balancing the costs of carbon gain and water transport: testing a new theoretical framework for plant functional ecology, Ecol. Lett., 17(1), 82-91, 2014.

  4. Difference of stand-scale transpiration between ridge and riparian area in a watershed with Japanese cypress plantation

    Science.gov (United States)

    Kume, T.; Tsuruta, K.; Komatsu, H.; Shinohara, Y.; Otsuki, K.

    2011-12-01

    Several different methods to assess water use are available, and the sap flux measurement technique is one of the most promising methods, especially in monotonous watershed. Previously, three spatial levels of scaling have been used to obtain bottom-up transpiration estimates based on the sap flux technique: from within-tree to tree, from tree to stand, and from stand to watershed or landscape. Although there are considerable variations that must be taken into account at each step, few studies have examined plot-to-plot variability of stand-scale transpirations. To design optimum sampling method to accurately estimate transpiration at the watershed-scale, it is indispensable to understand heterogeneity of stand-scale transpiration in a forested watershed and the factors determining the heterogeneity. This study was undertaken to clarify differences of stand-scale transpirations within a watershed and the factors determining the differences. To this aim, we conducted sap flux-based transpiration estimates in two plots such as a lower riparian (RZ) and an upper ridge (UZ) zone in a watershed with Japanese cypress plantation, Kyushu, Japan in two years. Tree height and diameter of breast height (DBH) were lager in RZ than those of UZ. The stand sapwood area (As) was lager in RZ than UZ (21.9 cm2h a-1, 16.8 cm2ha-1, respectively). Stand mean sap flux (Js) in RZ was almost same as that of UZ when relatively lower Js, while, Js in RZ was higher than that of UZ when relatively higher Js (i.e., bright days in summer season). Consequently, daily stand-scale transpiration (E), which is the multiple of As and Js, differed by two times between RZ and UZ in summer season. This study found significant heterogeneity of stand-scale transpiration within the watershed and that the differences could be caused by two aspects such as stand structure and sap flux velocity.

  5. Transpiration of greenhouse crops : an aid to climate management

    OpenAIRE

    Stanghellini, C.

    1987-01-01

    In this book some physical aspects of greenhouse climate are analyzed to show the direct interrelation between microclimate and crop transpiration. The energy balance of a greenhouse crop is shown to provide a sound physical framework to quantify the impact of microclimate on transpiration and to identify the constraints set on climate management by the termodynamic behaviour of the canopy. Before the relationship among microclimate, canopy temperature and transpiration is rendered i...

  6. Intercalibration study. Net of quality control of waters of the Department of Antioquia

    International Nuclear Information System (INIS)

    Parra M, C.M; Mejia Z, G.M.

    1999-01-01

    The norm ISO 5725 has set a series of statistical procedures for the evaluation of results for an intercalibration study which of course is a fundamental support for the setting of a quality control program that must be implement by every laboratory seeking accreditation. In the present paper the implementation of such procedures is shown for an exercise classified to be as of a uniform level. The chosen parameter was suspended solids which is included in the fees of the retributive rates set by the Ministerio del Medio Ambiente in Colombia. The exercise was done by the laboratories that are members of the Analytical Control of Water Web in the Department of Antioquia

  7. Thermal transpiration: A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    T, Joe Francis [Computational Nanotechnology Laboratory, School of Nano Science and Technology, National Institute of Technology Calicut, Kozhikode (India); Sathian, Sarith P. [Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai (India)

    2014-12-09

    Thermal transpiration is a phenomenon where fluid molecules move from the cold end towards the hot end of a channel under the influence of longitudinal temperature gradient alone. Although the phenomenon of thermal transpiration is observed at rarefied gas conditions in macro systems, the phenomenon can occur at atmospheric pressure if the characteristic dimensions of the channel is less than 100 nm. The flow through these nanosized channels is characterized by the free molecular flow regimes and continuum theory is inadequate to describe the flow. Thus a non-continuum method like molecular dynamics (MD) is necessary to study such phenomenon. In the present work, MD simulations were carried out to investigate the occurance of thermal transpiration in copper and platinum nanochannels at atmospheric pressure conditions. The mean pressure of argon gas confined inside the nano channels was maintained around 1 bar. The channel height is maintained at 2nm. The argon atoms interact with each other and with the wall atoms through the Lennard-Jones potential. The wall atoms are modelled using an EAM potential. Further, separate simulations were carried out where a Harmonic potential is used for the atom-atom interaction in the platinum channel. A thermally insulating wall was introduced between the low and high temperature regions and those wall atoms interact with fluid atoms through a repulsive potential. A reduced cut off radius were used to achieve this. Thermal creep is induced by applying a temperature gradient along the channel wall. It was found that flow developed in the direction of the increasing temperature gradient of the wall. An increase in the volumetric flux was observed as the length of the cold and the hot regions of the wall were increased. The effect of temperature gradient and the wall-fluid interaction strength on the flow parameters have been studied to understand the phenomenon better.

  8. Simultaneous viscous-inviscid coupling via transpiration

    International Nuclear Information System (INIS)

    Yiu, K.F.C.; Giles, M.B.

    1995-01-01

    In viscous-inviscid coupling analysis, the direct coupling technique and the inverse coupling technique are commonly adopted. However, stability and convergence of the algorithms derived are usually very unsatisfactory. Here, by using the transpiration technique to simulate the effect of the displacement thickness, a new simultaneous coupling method is derived. The integral boundary layer equations and the full potential equation are chosen to be the viscous-inviscid coupled system. After discretization, the Newton-Raphson technique is proposed to solve the coupled nonlinear system. Several numerical results are used to demonstrate the accuracy and efficiency of the proposed method. 15 refs., 23 figs

  9. Environmental and biological controls of urban tree transpiration in the Upper Midwest

    Science.gov (United States)

    Peters, E. B.; McFadden, J.; Montgomery, R.

    2009-12-01

    Urban trees provide a variety of ecosystem services to urban and suburban areas, including carbon uptake, climate amelioration, energy reduction, and stormwater management. Tree transpiration, in particular, modifies urban water budgets by providing an alternative pathway for water after rain events. The relative importance of environmental and biological controls on transpiration are poorly understood in urban areas, yet these controls are important for quantifying and scaling up the ecosystem services that urban trees provide at landscape and regional scales and predicting how urban ecosystems will respond to climate changes. The objectives of our study were to quantify the annual cycle of tree transpiration in an urban ecosystem and to determine how different urban tree species and plant functional types respond to environmental drivers. We continuously measured whole-tree transpiration using thermal dissipation sap flow at four urban forest stands that were broadly representative of the species composition and tree sizes found in a suburban residential neighborhood of Minneapolis-Saint Paul, Minnesota. A total of 40 trees, representing different species, plant functional types, successional stages, and xylem anatomy, were sampled throughout the 2007 and 2008 growing seasons (April-November). At each site we monitored soil moisture, air temperature, and relative humidity continuously, and we measured leaf area index weekly. Urban tree transpiration was strongly correlated with diurnal changes in vapor pressure deficit and photosynthetically active radiation and with seasonal changes in leaf area index. We found that plant functional type better explained species differences in transpiration per canopy area than either successional stage or xylem anatomy, largely due to differences in canopy structure between conifer and broad-leaf deciduous trees. We also observed inter-annual differences in transpiration rates due to a mid-season drought and longer growing

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

    Science.gov (United States)

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

    2018-04-01

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

  11. Monitoring Evaporation/Transpiration in a Vineyard from Two-Source Energy Balance and Radiometric Temperatures

    Science.gov (United States)

    Sánchez, Juan Manuel; Doña, Carolina; Cuxart, Joan; Caselles, Vicente; Niclòs, Raquel

    2014-05-01

    Water management and understanding of irrigation efficiency could be significantly improved if the components of evapotranspiration (ET) in row-crop systems (plants and soil interrows) could be quantified separately. This evaporation/transpiration (E/T) partition, and its daily and seasonal evolution, depends on a variety of biophysical and environmental factors. In this work we present an operational method to provide continuous E/T results avoiding soil or canopy disturbance. This technique is based on the combination of the surface-atmosphere energy exchange modeling together with an accurate remote thermal characterization of the crop elements. An experiment was carried out in a row-crop vineyard in Mallorca, Spain, from June 2012 to May 2013. A set of 6 thermal-infrared radiometers (IRTs) were mounted in a mast placed in the middle of a vineyard N-S row. Two IRTs pointed to the soil between rows and other two pointed to the plants from a frontal view, measuring both east and west sides of the row. A fifth IRT pointed upward to collect the downwelling sky radiance and the remaining IRT was mounted at 4.5-m height over the canopy measuring the composed soil-canopy temperature. Measurements of the four components of the net radiation over the canopy and soil heat fluxes, as well as air temperature, humidity, wind speed, and soil moisture, were collected and stored in 15-min averages. A two-source energy balance approach was applied to the vineyard from its appropriate thermal characterization. Total and separate soil/canopy components of net radiation, soil, sensible and latent heat fluxes were obtained every 15 minutes and averaged at hourly and daily scales. Comparison between observed and modeled values of available surface energy showed relative errors below 15%. An analysis of the partition E/T was conducted along the vineyard growing season and the different phenological stages. In this experiment, interrow soil evaporation reached as much as 1/3 of the

  12. The influence of CO2 enrichment on net photosynthesis of seagrass Zostera marina in a brackish water environment

    Directory of Open Access Journals (Sweden)

    Liina Pajusalu

    2016-11-01

    Full Text Available Seagrasses are distributed across the globe and their communities may play key roles in the coastal ecosystems. Seagrass meadows are expected to benefit from the increased carbon availability which might be used in photosynthesis in a future high CO2 world. The main aim of this study was to examine the effect of elevated pCO2 on the net photosynthesis of seagrass Zostera marina in a brackish water environment. The short-term mesocosm experiments were conducted in Kõiguste Bay (northern part of Gulf of Riga, the Baltic Sea in June-July 2013 and 2014. As the levels of pCO2 naturally range from ca. 150 μatm to well above 1000 μatm under summer conditions in Kõiguste Bay we chose to operate in mesocosms with the pCO2 levels of ca. 2000, ca. 1000 and ca. 200 μatm. Additionally, in 2014 the photosynthesis of Z. marina was measured outside of the mesocosm in the natural conditions. In the shallow coastal Baltic Sea seagrass Z. marina lives in a highly variable environment due to seasonality and rapid changes in meteorological conditions. This was demonstrated by the remarkable differences in water temperatures between experimental years of ca. 8°C. Thus, the current study also investigated the effect of elevated pCO2 in combination with short-term natural fluctuations of environmental factors, i.e. temperature and PAR on the photosynthesis of Z. marina. Our results show that elevated pCO2 alone did not enhance the photosynthesis of the seagrass. The photosynthetic response of Z. marina to CO2 enrichment was affected by changes in water temperature and light availability.

  13. 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

  14. Seasonal trends of light-saturated net photosynthesis and stomatal conductance of loblolly pine trees grown in contrasting environments of nutrition, water and carbon dioxide

    Science.gov (United States)

    Ramesh Murthy; Stanley J. Zarnoch; P.M. Dougherty

    1997-01-01

    Repeated measures analysis was used to evaluate the effect of long-term CO2 enhancement on seasonal trends of light-saturated rates of net photosynthesis (Asat) and stomatal conductance to water vapour (gsat) of 9-year-old loblolly pine (Pinus taeda L.; trees grown in a 2x2...

  15. 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

  16. Transpiration of greenhouse crops : an aid to climate management

    NARCIS (Netherlands)

    Stanghellini, C.

    1987-01-01

    In this book some physical aspects of greenhouse climate are analyzed to show the direct interrelation between microclimate and crop transpiration. The energy balance of a greenhouse crop is shown to provide a sound physical framework to quantify the impact of microclimate on transpiration

  17. 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.

  18. Effect of fluorine in the substrate on the intensity of stomato-cuticular transpiration and on photosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Navara, J

    1963-01-01

    This paper investigates the effect of fluorine in the substrate on the intensity of stomato-cuticular transpiration and on the intensity of photosynthesis in the common bean (Phaseolus vularis L.) in the early phases of ontogenetic development. Fluorine concentrations in the substrate in the range of 3 x 10/sup -3/ to 3 x 10/sup -4/ g/l produced no inhibition in the intensity of stomato-cuticular transpiration in 12-day-old test plants, whereas the intensity of photosynthesis was stimulated. An increase of 3 x 10/sup -3/ g/l in the fluorine level led to inhibition of these processes. As growth continued, an inhibitive effect on the intensity of stomato-cuticular transpiration was noted in 16-day-old plants even at a concentration of 3 x 10/sup -4/ g/l. The decrease in the intensity of stomato-cuticular transpiration is accompanied by an increase in the water-retention capacity of the leaf tissue. From these results, the conclusion can be drawn that the reduction in transpiration and photosynthesis is the result of a worsening in the plant's supply of water, resulting from disturbance of the absorptive capacity of the root system.

  19. Biomass Allocation Patterns Are Linked to Genotypic Differences in Whole-Plant Transpiration Efficiency in Sunflower

    Directory of Open Access Journals (Sweden)

    Luciano Velázquez

    2017-11-01

    Full Text Available Increased transpiration efficiency (the ratio of biomass to water transpired, TE could lead to increased drought tolerance under some water deficit scenarios. Intrinsic (i.e., leaf-level TE is usually considered as the primary source of variation in whole-plant TE, but empirical data usually contradict this assumption. Sunflower has a significant variability in TE, but a better knowledge of the effect of leaf and plant-level traits could be helpful to obtain more efficient genotypes for water use. The objective of this study was, therefore, to assess if genotypic variation in whole-plant TE is better related to leaf- or plant-level traits. Three experiments were conducted, aimed at verifying the existence of variability in whole-plant TE and whole-plant and leaf-level traits, and to assess their correlation. Sunflower public inbred lines and a segregating population of recombinant inbred lines were grown under controlled conditions and subjected to well-watered and water-deficit treatments. Significant genotypic variation was found for TE and related traits. These differences in whole-plant transpiration efficiency, both between genotypes and between plants within each genotype, showed no association to leaf-level traits, but were significantly and negatively correlated to biomass allocation to leaves and to the ratio of leaf area to total biomass. These associations are likely of a physiological origin, and not only a consequence of genetic linkage in the studied population. These results suggest that genotypic variation for biomass allocation could be potentially exploited as a source for increased transpiration efficiency in sunflower breeding programmes. It is also suggested that phenotyping for TE in this species should not be restricted to leaf-level measurements, but also include measurements of plant-level traits, especially those related to biomass allocation between photosynthetic and non-photosynthetic organs.

  20. Biomass Allocation Patterns Are Linked to Genotypic Differences in Whole-Plant Transpiration Efficiency in Sunflower.

    Science.gov (United States)

    Velázquez, Luciano; Alberdi, Ignacio; Paz, Cosme; Aguirrezábal, Luis; Pereyra Irujo, Gustavo

    2017-01-01

    Increased transpiration efficiency (the ratio of biomass to water transpired, TE) could lead to increased drought tolerance under some water deficit scenarios. Intrinsic (i.e., leaf-level) TE is usually considered as the primary source of variation in whole-plant TE, but empirical data usually contradict this assumption. Sunflower has a significant variability in TE, but a better knowledge of the effect of leaf and plant-level traits could be helpful to obtain more efficient genotypes for water use. The objective of this study was, therefore, to assess if genotypic variation in whole-plant TE is better related to leaf- or plant-level traits. Three experiments were conducted, aimed at verifying the existence of variability in whole-plant TE and whole-plant and leaf-level traits, and to assess their correlation. Sunflower public inbred lines and a segregating population of recombinant inbred lines were grown under controlled conditions and subjected to well-watered and water-deficit treatments. Significant genotypic variation was found for TE and related traits. These differences in whole-plant transpiration efficiency, both between genotypes and between plants within each genotype, showed no association to leaf-level traits, but were significantly and negatively correlated to biomass allocation to leaves and to the ratio of leaf area to total biomass. These associations are likely of a physiological origin, and not only a consequence of genetic linkage in the studied population. These results suggest that genotypic variation for biomass allocation could be potentially exploited as a source for increased transpiration efficiency in sunflower breeding programmes. It is also suggested that phenotyping for TE in this species should not be restricted to leaf-level measurements, but also include measurements of plant-level traits, especially those related to biomass allocation between photosynthetic and non-photosynthetic organs.

  1. Net Neutrality

    DEFF Research Database (Denmark)

    Savin, Andrej

    2017-01-01

    Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else.......Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else....

  2. Transpiration of gaseous elemental mercury through vegetation in a subtropical wetland in florida

    Energy Technology Data Exchange (ETDEWEB)

    Lindberg, Steven Eric [ORNL; Dong, Weijin [ORNL; Meyers, Tilden [NOAA, Oak Ridge, TN

    2002-07-01

    Four seasonal sampling campaigns were carried out in the Florida Everglades to measure elemental Hg vapor (Hg{sup o}) fluxes over emergent macrophytes using a modified Bowen ratio gradient approach. The predominant flux of Hg{sup o} over both invasive cattail and native sawgrass stands was emission; mean day time fluxes over cattail ranged from {approx}20 (winter) to {approx}40 (summer) ng m{sup -2} h{sup -1}. Sawgrass fluxes were about half those over cattail during comparable periods. Emission from vegetation significantly exceeded evasion of Hg{sup o} from the underlying water surface ({approx}1-2 ng m{sup -2} h{sup -1}) measured simultaneously using floating chambers. Among several environmental factors (e.g. CO{sub 2} flux, water vapor flux, wind speed, water, air and leaf temperature, and solar radiation), water vapor exhibited the strongest correlation with Hg{sup o} flux, and transpiration is suggested as an appropriate term to describe this phenomenon. The lack of significant Hg{sup o} emissions from a live, but uprooted (floating) cattail stand suggests that a likely source of the transpired Hg{sup o} is the underlying sediments. The pattern of Hg{sup o} fluxes typically measured indicated a diel cycle with two peaks, possibly related to different gas exchange dynamics: one in early morning related to lacunal gas release, and a second at midday related to transpiration; nighttime fluxes approached zero.

  3. 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.

  4. Wetland Surface Water Processes

    National Research Council Canada - National Science Library

    1993-01-01

    .... Temporary storage includes channel, overbank, basin, and groundwater storage. Water is removed from the wetland through evaporation, plant transpiration, channel, overland and tidal flow, and groundwater recharge...

  5. Transpiration in mango using Granier method

    OpenAIRE

    VELLAME, Lucas M.; COELHO FILHO, Mauricio A.; PAZ, Vital P. S.

    2009-01-01

    Objetivou-se, com esse trabalho avaliar o método Granier (sonda de dissipação térmica) para a cultura da manga quanto à viabilidade de uso em condições de campo e ajustar a equação de determinação do fluxo de seiva com base em medidas lisimétricas, iniciando-se com três mudas da variedade Tommy Atkins, plantadas em vasos que, colocados sobre plataforma de pesagem, funcionaram como lisímetros. A área condutora do caule (AS) foi determinada por meio da aplicação de corantes. Medidas de transpir...

  6. A process to estimate net infiltration using a site-scale water-budget approach, Rainier Mesa, Nevada National Security Site, Nevada, 2002–05

    Science.gov (United States)

    Smith, David W.; Moreo, Michael T.; Garcia, C. Amanda; Halford, Keith J.; Fenelon, Joseph M.

    2017-08-29

    This report documents a process used to estimate net infiltration from precipitation, evapotranspiration (ET), and soil data acquired at two sites on Rainier Mesa. Rainier Mesa is a groundwater recharge area within the Nevada National Security Site where recharged water flows through bedrock fractures to a deep (450 meters) water table. The U.S. Geological Survey operated two ET stations on Rainier Mesa from 2002 to 2005 at sites characterized by pinyon-juniper and scrub-brush vegetative cover. Precipitation and ET data were corrected to remove measurement biases and gap-filled to develop continuous datasets. Net infiltration (percolation below the root zone) and changes in root-zone water storage were estimated using a monthly water-balance model.Site-scale water-budget results indicate that the heavily-fractured welded-tuff bedrock underlying thin (water source for vegetation during dry periods. Annual precipitation during the study period ranged from fourth lowest (182 millimeters [mm]) to second highest (708 mm) on record (record = 55 years). Annual ET exceeded precipitation during dry years, indicating that the fractured-bedrock reservoir capacity is sufficient to meet atmospheric-evaporative demands and to sustain vegetation through extended dry periods. Net infiltration (82 mm) was simulated during the wet year after the reservoir was rapidly filled to capacity. These results support previous conclusions that preferential fracture flow was induced, resulting in an episodic recharge pulse that was detected in nearby monitoring wells. The occurrence of net infiltration only during the wet year is consistent with detections of water-level rises in nearby monitoring wells that occur only following wet years.

  7. Transpiration of montane Pinus sylvestris L. and Quercus pubescens Willd. forest stands measured with sap flow sensors in NE Spain

    Directory of Open Access Journals (Sweden)

    R. Poyatos

    2005-01-01

    Full Text Available Stand transpiration was measured during the 2003 and 2004 growing seasons using heat dissipation sap flow sensors in a Scots pine (Pinus sylvestris L. and a pubescent oak (Quercus pubescens Willd. forests located in a montane area of the Eastern Pyrenees (NE Spain. The first aim of the study was to assess the differences in quantitative estimates of transpiration (Ec and the response to evaporative demand of the two stands. Over the studied period of 2003, characterised by a severe drought episode during the summer, the oak stand (Ec was only 110 mm compared to the 239 mm transpired by the Scots pine stand, although the ratio of transpiration to reference evapotranspiration (Ec/ET0 in the oak stand compares well with the expected values predicted for low leaf area index (LAI oak forests in southern Europe. Scots pine showed a strong reduction in (Ec/ET0 as the drought developed, whereas pubescent oak was less affected by soil moisture deficits in the upper soil. As a second objective, and given the contrasting meteorological conditions between 2003 and 2004 summer periods, the interannual variability of transpiration was studied in the Scots pine plot. Rainfall during the summer months (June-September in 2003 was almost 40% less than in the same interval in 2004. Accordingly, transpiration was also reduced about 25% in 2003. Finally, Scots pine data from 2003 and 2004 was used to calibrate a simple transpiration model using ET0 and soil moisture deficit (SMD as input variables, and implicitly including stomatal responses to high vapour pressure deficits (Dd and soil water status.

  8. 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.

  9. WATER QUALITY AND ITS EFFECT ON GROWTH AND SURVIVAL RATE OF LOBSTER REARED IN FLOATING NET CAGE IN EKAS BAY, WEST NUSA TENGGARA PROVINCE

    Directory of Open Access Journals (Sweden)

    Muhammad Junaidi

    2015-02-01

    Full Text Available ABSTRACT The development of lobster farming in floating net cage in Ekas Bay caused an environmental degradation such as decrease water quality due to some aquaculture wastes. The purposes of this study were to determine the status of water quality and their effect on growth and survival rate of lobster reared in floating net cages (FNC in the Ekas Bay, West Nusa Tenggara Province. Water sample collection and handling referred to the APHA (1992. Analyses of water quality data were conducted using Principal Component Analysis. Determination of the water quality status of Ekas Bay was performed with STORET system. Multivariate analyses were used to determine the relationship between water quality, growth, and survival rate of lobster reared in FNC. Results showed that Ekas Bay water quality status was categorized in class C (medium contaminated, which exceeded some quality standard parameters such as ammonia (0.3 mg/l, nitrate (0.008 mg/l, and phosphate (0.015 mg/l. During lobster farming activities feeding with trash fish for 270 days, we obtained daily growth rate of  0.74% (lower than normal growth rate of 0.86%, survival rate of 66% (lower than normal survival rate of 86.7%, and feed conversion ratio of 11.15. Ammonia was found as a dominant factor reducing growth  and survival rate of lobster reared in FNC. Keywords: water quality, lobsters, growth, survival, Ekas Bay

  10. Computing the net primary productivity for a savannah-dominated ecosystem using stable isotopes: a case study of the Volta River Basin

    International Nuclear Information System (INIS)

    Hayford, E.K.

    2008-01-01

    The hydrologic systems and the terrestrial ecosystem of the Volta river basin in West Africa, play important role in the carbon cycle. This is so because of the coupling of water vapour release and CO 2 uptake during photosynthesis, expressed as water use efficiency or transpiration ratio. Hydrologic and land-cover data, together with stable isotope ratio measurements of δ 18 O and δD, and data from the global network of isotopes in precipitation (GNIP) are used to determine the net primary productivity (NPP) of the Savannah-dominated ecosystem. The δ 18 O and δD values in the Volta rivers range from -4.72 to 2.37 mm -l and from -35.28 to 9.30 mm -1 SMOW, respectively. The results indicate that the vegetation is supported by 380 km 3 of rainfall, out of which 50% is returned to the atmosphere via plant transpiration. Associated with annual transpiration is the NPP of 0.170 x 10 15 gCyr -1 or 428 gCm -2 from the terrestrial ecosystem. Modelled estimates of heterotrophic soil respiration in this study slightly exceeded the NPP estimates, implying a small source of CO 2 to the atmosphere. This condition does not favour the postulated existence of a major sink of atmospheric CO 2 in the Volta basin. (au)

  11. Petri Nets

    Indian Academy of Sciences (India)

    GENERAL I ARTICLE ... In Part 1 of this two-part article, we have seen im- ..... mable logic controller and VLSI arrays, office automation systems, workflow management systems, ... complex discrete event and real-time systems; and Petri nets.

  12. Vapour pressure deficit during growth has little impact on genotypic differences of transpiration efficiency at leaf and whole-plant level: an example from Populus nigra L.

    Science.gov (United States)

    Rasheed, Fahad; Dreyer, Erwin; Richard, Béatrice; Brignolas, Franck; Brendel, Oliver; Le Thiec, Didier

    2015-04-01

    Poplar genotypes differ in transpiration efficiency (TE) at leaf and whole-plant level under similar conditions. We tested whether atmospheric vapour pressure deficit (VPD) affected TE to the same extent across genotypes. Six Populus nigra genotypes were grown under two VPD. We recorded (1) (13)C content in soluble sugars; (2) (18)O enrichment in leaf water; (3) leaf-level gas exchange; and (4) whole-plant biomass accumulation and water use. Whole-plant and intrinsic leaf TE and (13)C content in soluble sugars differed significantly among genotypes. Stomatal conductance contributed more to these differences than net CO2 assimilation rate. VPD increased water use and reduced whole-plant TE. It increased intrinsic leaf-level TE due to a decline in stomatal conductance. It also promoted higher (18)O enrichment in leaf water. VPD had no genotype-specific effect. We detected a deviation in the relationship between (13)C in leaf sugars and (13)C predicted from gas exchange and the standard discrimination model. This may be partly due to genotypic differences in mesophyll conductance, and to its lack of sensitivity to VPD. Leaf-level (13)C discrimination was a powerful predictor of the genetic variability of whole-plant TE irrespective of VPD during growth. © 2014 John Wiley & Sons Ltd.

  13. 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.

  14. Changes in the physiological regulation of transpiration caused by the effects of industrial air pollution. [Cucumis sativus

    Energy Technology Data Exchange (ETDEWEB)

    Kozinka, V; Klasova, A; Niznansky, A

    1963-01-01

    Through Hygen's method of quantitative analysis of transpiration curves, the authors studied the intensity of stomatal and cuticular transpiration of germinating leaves of Cucumis sativus which were experimentally exposed to solid impurities containing F. The difference between the control and experimental plants shows that the impurities not only blocked the regulating system of breathing but also caused increased cuticular transpiration. Numerous lesions were observed; cuticle damage also spread to the inner tissues. A direct relationship between microscopic and macroscopic symptoms was not proven. The creation of conditions adverse to the normal development of the water balance was intensified when the impurities were dropped onto the surface of the leaves. The possible protective function of trichomes is mentioned, but applies only when the impurities settle on a dry surface.

  15. 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.

  16. 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.

  17. Hydraulic limits on maximum plant transpiration and the emergence of the safety-efficiency trade-off.

    Science.gov (United States)

    Manzoni, Stefano; Vico, Giulia; Katul, Gabriel; Palmroth, Sari; Jackson, Robert B; Porporato, Amilcare

    2013-04-01

    Soil and plant hydraulics constrain ecosystem productivity by setting physical limits to water transport and hence carbon uptake by leaves. While more negative xylem water potentials provide a larger driving force for water transport, they also cause cavitation that limits hydraulic conductivity. An optimum balance between driving force and cavitation occurs at intermediate water potentials, thus defining the maximum transpiration rate the xylem can sustain (denoted as E(max)). The presence of this maximum raises the question as to whether plants regulate transpiration through stomata to function near E(max). To address this question, we calculated E(max) across plant functional types and climates using a hydraulic model and a global database of plant hydraulic traits. The predicted E(max) compared well with measured peak transpiration across plant sizes and growth conditions (R = 0.86, P efficiency trade-off in plant xylem. Stomatal conductance allows maximum transpiration rates despite partial cavitation in the xylem thereby suggesting coordination between stomatal regulation and xylem hydraulic characteristics. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  18. 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.

  19. Modeling the Uptake and Transpiration of TCE Using Phreatophytic Trees

    National Research Council Canada - National Science Library

    Wise, Douglas

    1997-01-01

    .... The purpose of this research is to develop quantitative concepts for understanding the dynamics of TCE uptake and transpiration by phreatophytic trees over a short rotation woody crop time frame...

  20. [The study of transpiration influence on plant infrared radiation character].

    Science.gov (United States)

    Ling, Jun; Zhang, Shuan-Qin; Pan, Jia-Liang; Lian, Chang-Chun; Yang, Hui

    2012-07-01

    Studying vegetation infrared radiation character is the base of developing infrared camouflage and concealment technology of ground military target. Accurate fusion of target and background can be achieved by simulating formation mechanism of vegetation infrared radiation character. Leaf transpiration is characteristic physiological mechanism of vegetation and one of the main factors that influence its infrared radiation character. In the present paper, physical model of leaf energy balance is set up. Based on this model the influence of plant transpiration on leaf temperature is analyzed and calculated. The daily periodic variation of transpiration, leaf temperature and infrared radiation character of typical plants such as camphor tree and holly is actually measured with porometer and infrared thermal imaging system. By contrasting plant leaf with dryness leaf, experimental data indicates that plant transpiration can regulate leaf energy balance effectively and control leaf temperature in a reasonable range and suppress deep range variation of leaf infrared radiation character.

  1. 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.

  2. Leaf transpiration efficiency of some drought-resistant maize lines

    Science.gov (United States)

    Field measurements of leaf gas exchange in maize often indicate stomatal conductances higher than required to provide substomatal carbon dioxide concentrations saturating to photosynthesis. Thus maize leaves often operate at lower transpiration efficiency (TE) than potentially achievable for specie...

  3. Blanket testing in NET

    International Nuclear Information System (INIS)

    Chazalon, M.; Daenner, W.; Libin, B.

    1989-01-01

    The testing stages in NET for the performance assessment of the various breeding blanket concepts developed at the present time in Europe for DEMO (LiPb and ceramic blankets) and the requirements upon NET to perform these tests are reviewed. Typical locations available in NET for blanket testing are the central outboard segments and the horizontal ports of in-vessel sectors. These test positions will be connectable with external test loops. The number of test loops (helium, water, liquid metal) will be such that each major class of blankets can be tested in NET. The test positions, the boundary conditions and the external test loops are identified and the requirements for test blankets are summarized (author). 6

  4. Transpiration efficiency: new insights into an old story.

    Science.gov (United States)

    Vadez, Vincent; Kholova, Jana; Medina, Susan; Kakkera, Aparna; Anderberg, Hanna

    2014-11-01

    Producing more food per unit of water has never been as important as it is at present, and the demand for water by economic sectors other than agriculture will necessarily put a great deal of pressure on a dwindling resource, leading to a call for increases in the productivity of water in agriculture. This topic has been given high priority in the research agenda for the last 30 years, but with the exception of a few specific cases, such as water-use-efficient wheat in Australia, breeding crops for water-use efficiency has yet to be accomplished. Here, we review the efforts to harness transpiration efficiency (TE); that is, the genetic component of water-use efficiency. As TE is difficult to measure, especially in the field, evaluations of TE have relied mostly on surrogate traits, although this has most likely resulted in over-dependence on the surrogates. A new lysimetric method for assessing TE gravimetrically throughout the entire cropping cycle has revealed high genetic variation in different cereals and legumes. Across species, water regimes, and a wide range of genotypes, this method has clearly established an absence of relationships between TE and total water use, which dismisses previous claims that high TE may lead to a lower production potential. More excitingly, a tight link has been found between these large differences in TE in several crops and attributes of plants that make them restrict water losses under high vapour-pressure deficits. This trait provides new insight into the genetics of TE, especially from the perspective of plant hydraulics, probably with close involvement of aquaporins, and opens new possibilities for achieving genetic gains via breeding focused on this trait. Last but not least, small amounts of water used in specific periods of the crop cycle, such as during grain filling, may be critical. We assessed the efficiency of water use at these critical stages. © The Author 2014. Published by Oxford University Press on behalf of

  5. Biological and environmental controls on tree transpiration in a suburban landscape

    Science.gov (United States)

    Peters, Emily B.; McFadden, Joseph P.; Montgomery, Rebecca A.

    2010-12-01

    Tree transpiration provides a variety of ecosystem services in urban areas, including amelioration of urban heat island effects and storm water management. Tree species vary in the magnitude and seasonality of transpiration owing to differences in physiology, response to climate, and biophysical characteristics, thereby complicating efforts to manage evapotranspiration at city scales. We report sap flux measurements during the 2007 and 2008 growing seasons for dominant tree species in a suburban neighborhood of Minneapolis-Saint Paul, Minnesota, USA. Evergreen needleleaf trees had significantly higher growing season means and annual transpiration per unit canopy area (1.90 kg H2O m-2 d-1 and 307 kg H2O m-2 yr-1, respectively) than deciduous broadleaf trees (1.11 kg H2O m-2 d-1 and 153 kg H2O m-2 yr-1, respectively) because of a smaller projected canopy area (31.1 and 73.6 m2, respectively), a higher leaf area index (8.8 and 5.5 m2 m-2, respectively), and a longer growth season (8 and 4 months, respectively). Measurements also showed patterns consistent with the species' differences in xylem anatomy (conifer, ring porous, and diffuse porous). As the growing season progressed, conifer and diffuse porous genera had increased stomatal regulation to high vapor pressure deficit, while ring porous genera maintained greater and more constant stomatal regulation. These results suggest that evaporative responses to climate change in urban ecosystems will depend in part on species composition. Overall, plant functional type differences in canopy structure and growing season length were most important in explaining species' differences in midsummer and annual transpiration, offering an approach to predicting the evapotranspiration component of urban water budgets.

  6. Response of transpiration to rain pulses for two tree species in a semiarid plantation

    Science.gov (United States)

    Chen, Lixin; Zhang, Zhiqiang; Zeppel, Melanie; Liu, Caifeng; Guo, Junting; Zhu, Jinzhao; Zhang, Xuepei; Zhang, Jianjun; Zha, Tonggang

    2014-09-01

    Responses of transpiration ( E c) to rain pulses are presented for two semiarid tree species in a stand of Pinus tabulaeformis and Robinia pseudoacacia. Our objectives are to investigate (1) the environmental control over the stand transpiration after rainfall by analyzing the effect of vapor pressure deficit (VPD), soil water condition, and rainfall on the post-rainfall E c development and recovery rate, and (2) the species responses to rain pulses and implications on vegetation coverage under a changing rainfall regime. Results showed that the sensitivity of canopy conductance ( G c) to VPD varied under different incident radiation and soil water conditions, and the two species exhibited the same hydraulic control (-d G c/dlnVPD to G cref ratio) over transpiration. Strengthened physiological control and low sapwood area of the stand contributed to low E c. VPD after rainfall significantly influenced the magnitude and time series of post-rainfall stand E c. The fluctuation of post-rainfall VPD in comparison with the pre-rainfall influenced the E c recovery. Further, the stand E c was significantly related to monthly rainfall, but the recovery was independent of the rainfall event size. E c enhanced with cumulative soil moisture change (ΔVWC) within each dry-wet cycle, yet still was limited in large rainfall months. The two species had different response patterns of post-rainfall E c recovery. E c recovery of P. tabulaeformis was influenced by the pre- and post-rainfall VPD differences and the duration of rainless interval. R. pseudoacacia showed a larger immediate post-rainfall E c increase than P. tabulaeformis did. We, therefore, concluded that concentrated rainfall events do not trigger significant increase of transpiration unless large events penetrate the deep soil and the species differences of E c in response to pulses of rain may shape the composition of semiarid woodlands under future rainfall regimes.

  7. Plasma Wind Tunnel Testing of Electron Transpiration Cooling Concept

    Science.gov (United States)

    2017-02-28

    Colorado State University ETC Electron Transpiration Cooling LHTS Local Heat Transfer Simulation LTE Local Thermodynamic Equilibrium RCC Reinforced...ceramic electric material testing in plasma environment (not performed), 4. measurements and analysis of the Electron Transpiration Cooling (Sec. 4.2). 2...VKI 1D boundary layer code for computation of enthalpy and boundary layer parameters: a) iterate on ’virtually measured ’ heat flux, b) once enthalpy

  8. Effects of Biochar on the Net Greenhouse Gas Emissions under Continuous Flooding and Water-Saving Irrigation Conditions in Paddy Soils

    Directory of Open Access Journals (Sweden)

    Le Qi

    2018-05-01

    Full Text Available In this study, we investigated the greenhouse gas emission under different application of biochar in the conditions of continuous flooding and water-saving irrigation in paddy fields, whereas, plant and soil carbon sequestration were considered in the calculation of net greenhouse gas emissions. The emission rates of methane (CH4, carbon dioxide (CO2, and nitrous oxide (N2O gases were simultaneously monitored once every 7–10 days using the closed-chamber method. As a whole, the net greenhouse gas emission in the water-saving irrigation was more than that of the continuous flooding irrigation conditions. Compared with the water-saving irrigation, the continuous flooding irrigation significantly increased the CH4 in the control (CK and chemical fertilizer treatments (NPK. The CO2 emissions increased in each treatment of the water-saving irrigation condition, especially in the chemical fertilizer treatments (NPKFW. Similarly, the soil N2O emission was very sensitive to the water-saving irrigation condition. An interesting finding is that the biochar application in soils cut down the soil N2O emission more significantly than NPKFW in the water-saving irrigation condition while the effect of biochar increased under the continuous flooding irrigation condition.

  9. Africa-wide monitoring of small surface water bodies using multisource satellite data: a monitoring system for FEWS NET: chapter 5

    Science.gov (United States)

    Velpuri, Naga Manohar; Senay, Gabriel B.; Rowland, James; Verdin, James P.; Alemu, Henok; Melesse, Assefa M.; Abtew, Wossenu; Setegn, Shimelis G.

    2014-01-01

    Continental Africa has the highest volume of water stored in wetlands, large lakes, reservoirs, and rivers, yet it suffers from problems such as water availability and access. With climate change intensifying the hydrologic cycle and altering the distribution and frequency of rainfall, the problem of water availability and access will increase further. Famine Early Warning Systems Network (FEWS NET) funded by the United States Agency for International Development (USAID) has initiated a large-scale project to monitor small to medium surface water points in Africa. Under this project, multisource satellite data and hydrologic modeling techniques are integrated to monitor several hundreds of small to medium surface water points in Africa. This approach has been already tested to operationally monitor 41 water points in East Africa. The validation of modeled scaled depths with field-installed gauge data demonstrated the ability of the model to capture both the spatial patterns and seasonal variations. Modeled scaled estimates captured up to 60 % of the observed gauge variability with a mean root-mean-square error (RMSE) of 22 %. The data on relative water level, precipitation, and evapotranspiration (ETo) for water points in East and West Africa were modeled since 1998 and current information is being made available in near-real time. This chapter presents the approach, results from the East African study, and the first phase of expansion activities in the West Africa region. The water point monitoring network will be further expanded to cover much of sub-Saharan Africa. The goal of this study is to provide timely information on the water availability that would support already established FEWS NET activities in Africa. This chapter also presents the potential improvements in modeling approach to be implemented during future expansion in Africa.

  10. RESTful NET

    CERN Document Server

    Flanders, Jon

    2008-01-01

    RESTful .NET is the first book that teaches Windows developers to build RESTful web services using the latest Microsoft tools. Written by Windows Communication Foundation (WFC) expert Jon Flanders, this hands-on tutorial demonstrates how you can use WCF and other components of the .NET 3.5 Framework to build, deploy and use REST-based web services in a variety of application scenarios. RESTful architecture offers a simpler approach to building web services than SOAP, SOA, and the cumbersome WS- stack. And WCF has proven to be a flexible technology for building distributed systems not necessa

  11. Improved netting

    International Nuclear Information System (INIS)

    Bramley, A.; Clabburn, R.J.T.

    1976-01-01

    A method is described for producing netting composed of longitudinal and transverse threads of irradiation cross linked thermoplastic material, the threads being joined together at their crossings by moulded masses of cross linked thermoplastic material. The thread may be formed of polyethylene filaments, subjected to a radiation dose of 15 to 25 MR. The moulding can be conducted at 245 0 to 260 0 C or higher. The product is claimed to be an improved quality of netting, with bonds of increased strength between crossing threads. (U.K.)

  12. Horizontal ichthyoplankton tow-net system with unobstructed net opening

    Science.gov (United States)

    Nester, Robert T.

    1987-01-01

    The larval fish sampler described here consists of a modified bridle, frame, and net system with an obstruction-free net opening and is small enough for use on boats 10 m or less in length. The tow net features a square net frame attached to a 0.5-m-diameter cylinder-on-cone plankton net with a bridle designed to eliminate all obstructions forward of the net opening, significantly reducing currents and vibrations in the water directly preceding the net. This system was effective in collecting larvae representing more than 25 species of fish at sampling depths ranging from surface to 10 m and could easily be used at greater depths.

  13. Petri Nets

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 9. Petri Nets - Applications. Y Narahari. General Article Volume 4 Issue 9 September 1999 pp 44-52 ... Author Affiliations. Y Narahari1. Department of Computer Science and Automation, Indian Institute of Science, Bangalore 560 012, India.

  14. Net Gain

    International Development Research Centre (IDRC) Digital Library (Canada)

    Describing the effect of tax incentives for import, production, and sale of nets and insecticides; and ..... So far, China is the only country where a system for the routine treatment of ...... 1993), and the trials in Ecuador and Peru (Kroeger et al.

  15. Expression of Arabidopsis hexokinase in citrus guard cells controls stomatal aperture and reduces transpiration

    Directory of Open Access Journals (Sweden)

    Nitsan eLugassi

    2015-12-01

    Full Text Available Hexokinase (HXK is a sugar-phosphorylating enzyme involved in sugar-sensing. It has recently been shown that HXK in guard cells mediates stomatal closure and coordinates photosynthesis with transpiration in the annual species tomato and Arabidopsis. To examine the role of HXK in the control of the stomatal movement of perennial plants, we generated citrus plants that express Arabidopsis HXK1 (AtHXK1 under KST1, a guard cell-specific promoter. The expression of KST1 in the guard cells of citrus plants has been verified using GFP as a reporter gene. The expression of AtHXK1 in the guard cells of citrus reduced stomatal conductance and transpiration with no negative effect on the rate of photosynthesis, leading to increased water-use efficiency. The effects of light intensity and humidity on stomatal behavior were examined in rooted leaves of the citrus plants. The optimal intensity of photosynthetically active radiation and lower humidity enhanced stomatal closure of AtHXK1-expressing leaves, supporting the role of sugar in the regulation of citrus stomata. These results suggest that HXK coordinates photosynthesis and transpiration and stimulates stomatal closure not only in annual species, but also in perennial species.

  16. 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.

  17. Expression of Arabidopsis Hexokinase in Citrus Guard Cells Controls Stomatal Aperture and Reduces Transpiration.

    Science.gov (United States)

    Lugassi, Nitsan; Kelly, Gilor; Fidel, Lena; Yaniv, Yossi; Attia, Ziv; Levi, Asher; Alchanatis, Victor; Moshelion, Menachem; Raveh, Eran; Carmi, Nir; Granot, David

    2015-01-01

    Hexokinase (HXK) is a sugar-phosphorylating enzyme involved in sugar-sensing. It has recently been shown that HXK in guard cells mediates stomatal closure and coordinates photosynthesis with transpiration in the annual species tomato and Arabidopsis. To examine the role of HXK in the control of the stomatal movement of perennial plants, we generated citrus plants that express Arabidopsis HXK1 (AtHXK1) under KST1, a guard cell-specific promoter. The expression of KST1 in the guard cells of citrus plants has been verified using GFP as a reporter gene. The expression of AtHXK1 in the guard cells of citrus reduced stomatal conductance and transpiration with no negative effect on the rate of photosynthesis, leading to increased water-use efficiency. The effects of light intensity and humidity on stomatal behavior were examined in rooted leaves of the citrus plants. The optimal intensity of photosynthetically active radiation and lower humidity enhanced stomatal closure of AtHXK1-expressing leaves, supporting the role of sugar in the regulation of citrus stomata. These results suggest that HXK coordinates photosynthesis and transpiration and stimulates stomatal closure not only in annual species, but also in perennial species.

  18. 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

  19. Isotopic tracers for net primary productivity for a terrestrial ecosystem: a case study of the Volta River basin

    International Nuclear Information System (INIS)

    Hayford, E.K.; Odamtten, G.T.; Enu-Kwesi, L.

    2006-01-01

    The coupling effect of vapour release and CO2 uptake during photosynthesis plays an important role in the carbon and hydrologic cycles. The water use efficiency (WUE) for transpiration was used in calculating the net primary productivity (NPP) for terrestrial ecosystem. Three parameters were used in calculating the water and carbon balance of the River Volta watershed. These are 1) stable isotopes of hydrogen and oxygen, 2) long-term data on precipitation and evapotranspiration, and 3) stoichiometric relations of water and carbon. Results indicate that soils in the watershed annually respire 0.199 Pg C, and that the NPP is +0.029 Pg C yr-1. This implies an annual change in CO2 to the atmosphere within the watershed. Annually, River Volta watershed receives about 380 km3 of rainfall; approximately 50 per cent of which is returned to the atmosphere through plant transpiration. Associated with annual transpiration flux is a carbon flux of 0.170 x 1015 g C yr-1 or 428 g C m-2 yr-1 from the terrestrial ecosystem. Modeled estimates of heterotrophic soil respiration exceeds slightly the estimated NPP values, implying that carbon flux to and from the Volta river watershed is close to being in balance. In other words, the watershed releases annually more carbon dioxide to the atmosphere than it takes. Apart from the terrestrial carbon flux, the balance of photosynthesis and respiration in the Volta lake was also examined. The lake was found to release carbon dioxide to the atmosphere although the magnitude of the flux is smaller than that of the terrestrial ecosystem. (au)

  20. Spatial Variability of Tree Transpiration Along a Soil Drainage Gradient of Boreal Black Spruce Forest

    Science.gov (United States)

    Angstmann, J. L.; Ewers, B. E.; Kwon, H.; Bond-Lamberty, B.; Amiro, B.; Gower, S. T.

    2008-12-01

    Boreal forests are an integral component in obtaining a predictive understanding of global climate change because they comprise 33% of the world's forests and store large amounts of carbon. Much of this carbon storage is a result of peat formation in cold, poorly-drained soils. Transpiration plays a crucial role in the interaction between carbon and water cycles due to stomatal control of these fluxes. The primary focus of this study is to quantify the spatial variability and drivers of tree transpiration in boreal forest stands across a well- to poorly-drained soil drainage gradient. Species composition of this region of boreal forest changes during succession in well-drained soils from being primarily dominated by Picea mariana with co-dominant Pinus banksiana and Populus tremuloides in younger stands to being dominated solely by Picea marianain older stands. Poorly-drained soils are dominated by Picea mariana and change little with succession. Previous work in well-drained stands showed that 1) tree transpiration changed substantially with stand age due to sapwood-to-leaf area ratio dynamics and 2) minimum leaf water potential (Ψ) was kept constant to prevent excessive cavitation. We hypothesized that 1) minimum Ψ would be constant, 2) transpiration would be proportional to the sapwood-to-leaf area ratio across a soil drainage gradient, and 3) spatial relationships between trees would vary depending on stomatal responses to vapor pressure deficit (D). We tested these hypotheses by measuring Ψ of 33 trees and sap flux from 204 trees utilizing cyclic sampling constructed to study spatial relationships. Measurements were conducted at a 42-year-old stand representing maximum tree diversity during succession. There were no significant differences between growing season averaged Ψ in well- (-0.35 and -1.37 for pre-dawn and mid-day respectively) and poorly- drained soil conditions (-0.38 and -1.41 for pre-dawn and mid-day respectively) for Picea mariana. Water use

  1. Coupled eco-hydrology and biogeochemistry algorithms enable the simulation of water table depth effects on boreal peatland net CO2 exchange

    Science.gov (United States)

    Mezbahuddin, Mohammad; Grant, Robert F.; Flanagan, Lawrence B.

    2017-12-01

    Water table depth (WTD) effects on net ecosystem CO2 exchange of boreal peatlands are largely mediated by hydrological effects on peat biogeochemistry and the ecophysiology of peatland vegetation. The lack of representation of these effects in carbon models currently limits our predictive capacity for changes in boreal peatland carbon deposits under potential future drier and warmer climates. We examined whether a process-level coupling of a prognostic WTD with (1) oxygen transport, which controls energy yields from microbial and root oxidation-reduction reactions, and (2) vascular and nonvascular plant water relations could explain mechanisms that control variations in net CO2 exchange of a boreal fen under contrasting WTD conditions, i.e., shallow vs. deep WTD. Such coupling of eco-hydrology and biogeochemistry algorithms in a process-based ecosystem model, ecosys, was tested against net ecosystem CO2 exchange measurements in a western Canadian boreal fen peatland over a period of drier-weather-driven gradual WTD drawdown. A May-October WTD drawdown of ˜ 0.25 m from 2004 to 2009 hastened oxygen transport to microbial and root surfaces, enabling greater microbial and root energy yields and peat and litter decomposition, which raised modeled ecosystem respiration (Re) by 0.26 µmol CO2 m-2 s-1 per 0.1 m of WTD drawdown. It also augmented nutrient mineralization, and hence root nutrient availability and uptake, which resulted in improved leaf nutrient (nitrogen) status that facilitated carboxylation and raised modeled vascular gross primary productivity (GPP) and plant growth. The increase in modeled vascular GPP exceeded declines in modeled nonvascular (moss) GPP due to greater shading from increased vascular plant growth and moss drying from near-surface peat desiccation, thereby causing a net increase in modeled growing season GPP by 0.39 µmol CO2 m-2 s-1 per 0.1 m of WTD drawdown. Similar increases in GPP and Re caused no significant WTD effects on modeled

  2. Coupled eco-hydrology and biogeochemistry algorithms enable the simulation of water table depth effects on boreal peatland net CO2 exchange

    Directory of Open Access Journals (Sweden)

    M. Mezbahuddin

    2017-12-01

    Full Text Available Water table depth (WTD effects on net ecosystem CO2 exchange of boreal peatlands are largely mediated by hydrological effects on peat biogeochemistry and the ecophysiology of peatland vegetation. The lack of representation of these effects in carbon models currently limits our predictive capacity for changes in boreal peatland carbon deposits under potential future drier and warmer climates. We examined whether a process-level coupling of a prognostic WTD with (1 oxygen transport, which controls energy yields from microbial and root oxidation–reduction reactions, and (2 vascular and nonvascular plant water relations could explain mechanisms that control variations in net CO2 exchange of a boreal fen under contrasting WTD conditions, i.e., shallow vs. deep WTD. Such coupling of eco-hydrology and biogeochemistry algorithms in a process-based ecosystem model, ecosys, was tested against net ecosystem CO2 exchange measurements in a western Canadian boreal fen peatland over a period of drier-weather-driven gradual WTD drawdown. A May–October WTD drawdown of  ∼  0.25 m from 2004 to 2009 hastened oxygen transport to microbial and root surfaces, enabling greater microbial and root energy yields and peat and litter decomposition, which raised modeled ecosystem respiration (Re by 0.26 µmol CO2 m−2 s−1 per 0.1 m of WTD drawdown. It also augmented nutrient mineralization, and hence root nutrient availability and uptake, which resulted in improved leaf nutrient (nitrogen status that facilitated carboxylation and raised modeled vascular gross primary productivity (GPP and plant growth. The increase in modeled vascular GPP exceeded declines in modeled nonvascular (moss GPP due to greater shading from increased vascular plant growth and moss drying from near-surface peat desiccation, thereby causing a net increase in modeled growing season GPP by 0.39 µmol CO2 m−2 s−1 per 0.1 m of WTD drawdown. Similar increases in

  3. 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

  4. Net Locality

    DEFF Research Database (Denmark)

    de Souza e Silva, Adriana Araujo; Gordon, Eric

    Provides an introduction to the new theory of Net Locality and the profound effect on individuals and societies when everything is located or locatable. Describes net locality as an emerging form of location awareness central to all aspects of digital media, from mobile phones, to Google Maps......, to location-based social networks and games, such as Foursquare and facebook. Warns of the threats these technologies, such as data surveillance, present to our sense of privacy, while also outlining the opportunities for pro-social developments. Provides a theory of the web in the context of the history...... of emerging technologies, from GeoCities to GPS, Wi-Fi, Wiki Me, and Google Android....

  5. 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.

  6. Energy Balance, Evapo-transpiration and Dew deposition in the Dead Sea Valley

    Science.gov (United States)

    Metzger, Jutta; Corsmeier, Ulrich

    2016-04-01

    The Dead Sea is a unique place on earth. It is a terminal hypersaline lake, located at the lowest point on earth with a lake level of currently -429 m above mean sea level (amsl). It is located in a transition zone of semiarid to arid climate conditions, which makes it highly sensible to climate change (Alpert1997, Smiatek2011). The Virtual Institute DEad SEa Research Venue (DESERVE) is an international project funded by the German Helmholtz Association and was established to study coupled atmospheric hydrological, and lithospheric processes in the changing environment of the Dead Sea. At the moment the most prominent environmental change is the lake level decline of approximately 1 m / year due to anthropogenic interferences (Gertman, 2002). This leads to noticeable changes in the fractions of the existing terrestrial surfaces - water, bare soil and vegetated areas - in the valley. Thus, the partitioning of the net radiation in the valley changes as well. To thoroughly study the atmospheric and hydrological processes in the Dead Sea valley, which are driven by the energy balance components, sound data of the energy fluxes of the different surfaces are necessary. Before DESERVE no long-term monitoring network simultaneously measuring the energy balance components of the different surfaces in the Dead Sea valley was available. Therefore, three energy balance stations were installed at three characteristic sites at the coast-line, over bare soil, and within vegetation, measuring all energy balance components by using the eddy covariance method. The results show, that the partitioning of the energy into sensible and latent heat flux on a diurnal scale is totally different at the three sites. This results in gradients between the sites, which are e.g. responsible for the typical diurnal wind systems at the Dead Sea. Furthermore, driving forces of evapo-transpiration at the sites were identified and a detailed analysis of the daily evaporation and dew deposition rates

  7. Thermal performance of a transpired solar collector updraft tower

    International Nuclear Information System (INIS)

    Eryener, Dogan; Hollick, John; Kuscu, Hilmi

    2017-01-01

    Highlights: • Transpired solar collector updraft tower has been studied experimentally. • Transpired solar collector updraft tower efficiency ranges from 60 to 80%. • A comparison has been made with other SUT prototypes. • Three times higher efficiency compared to the glazed collectors of conventional solar towers. - Abstract: A novel solar updraft tower prototype, which consists of transpired solar collector, is studied, its function principle is described and its experimental thermal performance is presented for the first time. A test unit of transpired solar collector updraft tower was installed at the campus of Trakya University Engineering Faculty in Edirne-Turkey in 2014. Solar radiation, ambient temperature, collector cavity temperatures, and chimney velocities were monitored during summer and winter period. The results showed that transpired solar collector efficiency ranges from 60% to 80%. The maximum temperature rise in the collector area is found to be 16–18 °C on the typical sunny day. Compared to conventional solar tower glazed collectors, three times higher efficiency is obtained. With increased thermal efficiency, large solar collector areas for solar towers can be reduced in half or less.

  8. Differentiating transpiration from evaporation in seasonal agricultural wetlands and the link to advective fluxes in the root zone

    International Nuclear Information System (INIS)

    Bachand, P.A.M.; Bachand, S.; Fleck, J.; Anderson, F.; Windham-Myers, L.

    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 flow rates and tracer concentrations at wetland inflows and outflows. We used two ideal reactor model solutions, a continuous flow stirred 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 non-ideal agricultural wetlands in which check ponds are in series. Using a flux model, 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 biogeochemical mechanisms affecting dissolved constituent cycling in the root zone. In addition, our understanding of

  9. Water stress detection using radar

    NARCIS (Netherlands)

    van Emmerik, T.H.M.

    2017-01-01

    Vegetation is a crucial part of the water and carbon cycle. Through photosynthesis carbon is assimilated for biomass production, and oxygen is released into the atmosphere. During this process, water is transpired through the stomata, and is redistributed in the plant. Transpired water is refilled

  10. Quantifying the net benefit impacts of the Troy Waste Water Treatment Plant on Steelhead Habitat in the West Fork Little Bear Creek drainage

    Science.gov (United States)

    Sanchez-Murillo, R.; Brooks, E. S.; Boll, J.

    2010-12-01

    Discharge of waste water treatment plants (WWTPs) typically is viewed to result in water quality impairment. However, WWTPs can also be a source of nutrients to enhance the salmonid food web as well as an efficient way to maintain acceptable water temperature regimes and flow conditions during summer. We observed this paradox in West Fork Little Bear Creek (WFLB) in the City of Troy, Idaho. Despite the nutrient load, the WFLB had the highest Steelhead trout density in the watershed, with a mean density of 13.2 fish/100 m2. The objective of this project was to utilize a water quality model, QUAL2kw, and an ecology assessment to examine how the nutrient load from the WWTP affects: a) habitat conditions for steelhead juveniles, and b) physic-chemical parameters. Four monitoring stations were installed from May through November in 2009 and 2010. An undisturbed creek was used as a control site in 2010. Dissolved oxygen (DO), electrical conductivity, temperature, and discharge were measured continuously at each monitoring station. Weekly samples were collected at each monitoring station and analyzed for nitrate, nitrite, ammonia, total Kjeldahl nitrogen, total phosphorous, and orthophosphates. In 2010, Chlorophyll a was analyzed weekly, while bottom algae biomass was determined monthly. Results show that during summer months, the WWTP provides the majority of the flow (0.1 cfs) in the creek. Water samples and DO measurements taken 200 m downstream of the plant during late summer months indicate that nitrification process leads to low DO level well below the state standard of 6 mg/L for cold water biota. However dissolved oxygen levels recover within 1 km downstream. Discharge data suggest that without the flow from the treatment most of the creek would dry during late summer months. Abundance of macroinverbrates, high primary productivity, and sustained flow during summer suggests that the effluent from the WWTP is a net benefit to the Steelhead habitat in the basin

  11. Enhanced transpiration by riparian buffer trees in response to advection in a humid temperate agricultural landscape

    Science.gov (United States)

    Hernandez-Santana, V.; Asbjornsen, H.; Sauer, T.; Isenhart, T.; Schilling, K.; Schultz, Ronald

    2011-01-01

    Riparian buffers are designed as management practices to increase infiltration and reduce surface runoff and transport of sediment and nonpoint source pollutants from crop fields to adjacent streams. Achieving these ecosystem service goals depends, in part, on their ability to remove water from the soil via transpiration. In these systems, edges between crop fields and trees of the buffer systems can create advection processes, which could influence water use by trees. We conducted a field study in a riparian buffer system established in 1994 under a humid temperate climate, located in the Corn Belt region of the Midwestern U.S. (Iowa). The goals were to estimate stand level transpiration by the riparian buffer, quantify the controls on water use by the buffer system, and determine to what extent advective energy and tree position within the buffer system influence individual tree transpiration rates. We primarily focused on the water use response (determined with the Heat Ratio Method) of one of the dominant species (Acer saccharinum) and a subdominant (Juglans nigra). A few individuals of three additional species (Quercus bicolor, Betula nigra, Platanus occidentalis) were monitored over a shorter time period to assess the generality of responses. Meteorological stations were installed along a transect across the riparian buffer to determine the microclimate conditions. The differences found among individuals were attributed to differences in species sap velocities and sapwood depths, location relative to the forest edge and prevailing winds and canopy exposure and dominance. Sapflow rates for A. saccharinum trees growing at the SE edge (prevailing winds) were 39% greater than SE interior trees and 30% and 69% greater than NW interior and edge trees, respectively. No transpiration enhancement due to edge effect was detected in the subdominant J. nigra. The results were interpreted as indicative of advection effects from the surrounding crops. Further, significant

  12. Estimation of net ecosystem metabolism of seagrass meadows in the coastal waters of the East Sea and Black Sea using the noninvasive eddy covariance technique

    Science.gov (United States)

    Lee, Jae Seong; Kang, Dong-Jin; Hineva, Elitsa; Slabakova, Violeta; Todorova, Valentina; Park, Jiyoung; Cho, Jin-Hyung

    2017-06-01

    We measured the community-scale metabolism of seagrass meadows in Bulgaria (Byala [BY]) and Korea (Hoopo Bay [HP]) to understand their ecosystem function in coastal waters. A noninvasive in situ eddy covariance technique was applied to estimate net O2 flux in the seagrass meadows. From the high-quality and high-resolution time series O2 data acquired over > 24 h, the O2 flux driven by turbulence was extracted at 15-min intervals. The spectrum analysis of vertical flow velocity and O2 concentration clearly showed well-developed turbulence characteristics in the inertial subrange region. The hourly averaged net O2 fluxes per day ranged from -474 to 326 mmol O2 m-2 d-1 (-19 ± 41 mmol O2 m-2 d-1) at BY and from -74 to 482 mmol O2 m-2 d-1 (31 ± 17 mmol O2 m-2 d-1) at HP. The net O2 production rapidly responded to photosynthetically available radiation (PAR) and showed a good relationship between production and irradiance (P-I curve). The hysteresis pattern of P-I relationships during daytime also suggested increasing heterotrophic respiration in the afternoon. With the flow velocity between 3.30 and 6.70 cm s-1, the community metabolism during daytime and nighttime was significantly increased by 20 times and 5 times, respectively. The local hydrodynamic characteristics may be vital to determining the efficiency of community photosynthesis. The net ecosystem metabolism at BY was estimated to be -17 mmol O2 m-2 d-1, which was assessed as heterotrophy. However, that at HP was 36 mmol O2 m-2 d-1, which suggested an autotrophic state.

  13. 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

  14. A two-step approach to estimating selectivity and fishing power of research gill nets used in Greenland waters

    DEFF Research Database (Denmark)

    Hovgård, Holger

    1996-01-01

    by normal distributions and could be related to mesh size in accordance with the principle of geometrical similarity. In the second step the selection parameters were estimated by a nonlinear least squares fit. The model also estimated the relative efficiency of the two capture processes and the fishing......Catches of Atlantic cod (Gadus morhua) from Greenland gill-net surveys were analyzed by a two-step approach. In the initial step the form of the selection curve was identified as binormal, which was caused by fish being gilled or caught by the maxillae. Both capture processes could be described...

  15. Hydraulic redistribution of soil water by roots affects whole-stand evapotranspiration and net ecosystem carbon exchange

    Science.gov (United States)

    J.-C. Domec; J.S. King; A. Noormets; E. Treasure; M.J. Gavazzi; G. Sun; S.G. McNulty

    2010-01-01

    Hydraulic redistribution (HR) of water via roots from moist to drier portions of the soil occurs in many ecosystems, potentially influencing both water use and carbon assimilation. By measuring soil water content, sap flow and eddy covariance, we investigated the temporal variability of HR in a loblolly pine (Pinus taeda) plantation during months of...

  16. Nitrogen regulation of transpiration controls mass-flow acquisition of nutrients.

    Science.gov (United States)

    Matimati, Ignatious; Verboom, G Anthony; Cramer, Michael D

    2014-01-01

    Transpiration may enhance mass-flow of nutrients to roots, especially in low-nutrient soils or where the root system is not extensively developed. Previous work suggested that nitrogen (N) may regulate mass-flow of nutrients. Experiments were conducted to determine whether N regulates water fluxes, and whether this regulation has a functional role in controlling the mass-flow of nutrients to roots. Phaseolus vulgaris were grown in troughs designed to create an N availability gradient by restricting roots from intercepting a slow-release N source, which was placed at one of six distances behind a 25 μm mesh from which nutrients could move by diffusion or mass-flow (termed 'mass-flow' treatment). Control plants had the N source supplied directly to their root zone so that N was available through interception, mass-flow, and diffusion (termed 'interception' treatment). 'Mass-flow' plants closest to the N source exhibited 2.9-fold higher transpiration (E), 2.6-fold higher stomatal conductance (gs), 1.2-fold higher intercellular [CO2] (Ci), and 3.4-fold lower water use efficiency than 'interception' plants, despite comparable values of photosynthetic rate (A). E, gs, and Ci first increased and then decreased with increasing distance from the N source to values even lower than those of 'interception' plants. 'Mass-flow' plants accumulated phosphorus and potassium, and had maximum concentrations at 10mm from the N source. Overall, N availability regulated transpiration-driven mass-flow of nutrients from substrate zones that were inaccessible to roots. Thus when water is available, mass-flow may partially substitute for root density in providing access to nutrients without incurring the costs of root extension, although the efficacy of mass-flow also depends on soil nutrient retention and hydraulic properties.

  17. Partitioning of evaporation into transpiration, soil evaporation and interception : A comparison between isotope measurements and a HYDRUS-1D model + Corrigendum

    NARCIS (Netherlands)

    Sutanto, S.J.; Wenninger, J.; Coenders-Gerrits, A.M.J.; Uhlenbrook, S.

    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

  18. Variable coupling between sap-flow and transpiration in pine trees under drought conditions

    Science.gov (United States)

    Preisler, Yakir; Tatarinov, Fyodor; Rohatyn, Shani; Rotenberg, Eyal; Grunzweig, Jose M.; Yakir, Dan

    2016-04-01

    Changes in diurnal patterns in water transport and physiological activities in response to changes in environmental conditions are important adjustments of trees to drought. The rate of sap flow (SF) in trees is expected to be in agreement with the rate of tree-scale transpiration (T) and provides a powerful measure of water transport in the soil-plant-atmosphere system. The aim of this five-years study was to investigate the temporal links between SF and T in Pinus halepensis exposed to extreme seasonal drought in the Yatir forest in Israel. We continuously measured SF (20 trees), the daily variations in stem diameter (ΔDBH, determined with high precision dendrometers; 8 trees), and ecosystem evapotranspiration (ET; eddy covariance), which were complemented with short-term campaigns of leaf-scale measurements of H2O and CO2 gas exchange, water potentials, and hydraulic conductivity. During the rainy season, tree SF was well synchronized with ecosystem ET, reaching maximum rates during midday in all trees. However, during the dry season, the daily SF trends greatly varied among trees, allowing a classification of trees into three classes: 1) Trees that remain with SF maximum at midday, 2) trees that advanced their SF peak to early morning, and 3) trees that delayed their SF peak to late afternoon hours. This classification remained valid for the entire study period (2010-2015), and strongly correlated with tree height and DBH, and to a lower degree with crown size and competition index. In the dry season, class 3 trees (large) tended to delay the timing of SF maximum to the afternoon, and to advance their maximum diurnal DBH to early morning, while class 2 trees (smaller) advanced their SF maximum to early morning and had maximum daily DBH during midday and afternoon. Leaf-scale transpiration (T), measurements showed a typical morning peak in all trees, irrespective of classification, and a secondary peak in the afternoon in large trees only. Water potential and

  19. Transpiration rates of rice plants treated with Trichoderma spp.

    Science.gov (United States)

    Doni, Febri; Anizan, I.; Che Radziah C. M., Z.; Yusoff, Wan Mohtar Wan

    2014-09-01

    Trichoderma spp. are considered as successful plant growth promoting fungi and have positive role in habitat engineering. In this study, the potential for Trichoderma spp. to regulate transpiration process in rice plant was assessed experimentally under greenhouse condition using a completely randomized design. The study revealed that Trichoderma spp. have potential to enhance growth of rice plant through transpirational processes. The results of the study add to the advancement of the understanding as to the role of Trichoderma spp. in improving rice physiological process.

  20. Modelling non-steady-state isotope enrichment of leaf water in a gas-exchange cuvette environment.

    Science.gov (United States)

    Song, Xin; Simonin, Kevin A; Loucos, Karen E; Barbour, Margaret M

    2015-12-01

    The combined use of a gas-exchange system and laser-based isotope measurement is a tool of growing interest in plant ecophysiological studies, owing to its relevance for assessing isotopic variability in leaf water and/or transpiration under non-steady-state (NSS) conditions. However, the current Farquhar & Cernusak (F&C) NSS leaf water model, originally developed for open-field scenarios, is unsuited for use in a gas-exchange cuvette environment where isotope composition of water vapour (δv ) is intrinsically linked to that of transpiration (δE ). Here, we modified the F&C model to make it directly compatible with the δv -δE dynamic characteristic of a typical cuvette setting. The resultant new model suggests a role of 'net-flux' (rather than 'gross-flux' as suggested by the original F&C model)-based leaf water turnover rate in controlling the time constant (τ) for the approach to steady sate. The validity of the new model was subsequently confirmed in a cuvette experiment involving cotton leaves, for which we demonstrated close agreement between τ values predicted from the model and those measured from NSS variations in isotope enrichment of transpiration. Hence, we recommend that our new model be incorporated into future isotope studies involving a cuvette condition where the transpiration flux directly influences δv . There is an increasing popularity among plant ecophysiologists to use a gas-exchange system coupled to laser-based isotope measurement for investigating non-steady state (NSS) isotopic variability in leaf water (and/or transpiration); however, the current Farquhar & Cernusak (F&C) NSS leaf water model is unsuited for use in a gas-exchange cuvette environment due to its implicit assumption of isotope composition of water vapor (δv ) being constant and independent of that of transpiration (δE ). In the present study, we modified the F&C model to make it compatible with the dynamic relationship between δv and δE as is typically associated

  1. KM3NeT

    CERN Multimedia

    KM3NeT is a large scale next-generation neutrino telescope located in the deep waters of the Mediterranean Sea, optimized for the discovery of galactic neutrino sources emitting in the TeV energy region.

  2. Stand, species, and individual traits impact transpiration in historically disturbed forests.

    Science.gov (United States)

    Blakely, B.; Rocha, A. V.; McLachlan, J. S.

    2017-12-01

    Historic logging disturbances have changed the structure and species composition of most Northern temperate forests. These changes impact the process of transpiration - which in turn impacts canopy surface temperature - but the links among structure, composition, and transpiration remain unclear. For this reason, ecosystem models typically use simplified structure and composition to simulate the impact of disturbances on forest transpiration. However, such simplifications ignore real variability among stands, species, and individual trees that may strongly influence transpiration across spatial and temporal scales. To capture this variability, we monitored transpiration in 48 individual trees of multiple species in both undisturbed (400+ yr) and historically logged (80 - 120 yr) forests. Using modern and historic forest surveys, we upscaled our observations to stand and regional scales to identify the key changes impacting transpiration. We extended these inferences by establishing a relationship between transpiration and measured surface temperature, linking disturbance-induced changes in structure and composition to local and regional climate. Despite greater potential evapotranspiration and basal area, undisturbed forest transpired less than disturbed (logged) forest. Transpiration was a strong predictor of surface temperature, and the canopy surface was warmer in undisturbed forest. Transpiration differences among disturbed and undisturbed forests resulted from (1) lesser transpiration and dampened seasonality in evergreen species (2) greater transpiration in younger individuals within a species, and (3) strong transpiration by large individuals. When transpiration was scaled to the stand or regional level in a simplified manner (e.g. a single transpiration rate for all deciduous individuals), the resulting estimates differed markedly from the original. Stand- species- and individual-level traits are therefore essential for understanding how transpiration and

  3. Assessment of transpiration efficiency in peanut (Arachis hypogaea L.) under drought using a lysimetric system.

    Science.gov (United States)

    Ratnakumar, P; Vadez, V; Nigam, S N; Krishnamurthy, L

    2009-11-01

    Transpiration efficiency (TE) is an important trait for drought tolerance in peanut (Arachis hypogaea L.). The variation in TE was assessed gravimetrically using a long time interval in nine peanut genotypes (Chico, ICGS 44, ICGV 00350, ICGV 86015, ICGV 86031, ICGV 91114, JL 24, TAG 24 and TMV 2) grown in lysimeters under well-watered or drought conditions. Transpiration was measured by regularly weighing the lysimeters, in which the soil surface was mulched with a 2-cm layer of polythene beads. TE in the nine genotypes used varied from 1.4 to 2.9 g kg(-1) under well-watered and 1.7 to 2.9 g kg(-1) under drought conditions, showing consistent variation in TE among genotypes. A higher TE was found in ICGV 86031 in both well-watered and drought conditions and lower TE was found in TAG-24 under both water regimes. Although total water extraction differed little across genotypes, the pattern of water extraction from the soil profile varied among genotypes. High water extraction within 24 days following stress imposition was negatively related to pod yield (r(2) = 0.36), and negatively related to water extraction during a subsequent period of 32 days (r(2) = 0.73). By contrast, the latter, i.e. water extraction during a period corresponding to grain filling (24 to 56 days after flowering) was positively related to pod yield (r(2) = 0.36). TE was positively correlated with pod weight (r(2) = 0.30) under drought condition. Our data show that under an intermittent drought regime, TE and water extraction from the soil profile during a period corresponding to pod filling were the most important components.

  4. 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

  5. Solar-induced chlorophyll fluorescence tracks the trend of canopy stomatal conductance and transpiration at diurnal and seasonal scales

    Science.gov (United States)

    Zhang, Y.; Shan, N.; Ju, W.; Chen, J.

    2017-12-01

    Transpiration is the process of plant water loss through the stomata on the leaf surface and plays a key role in the energy and water balance of the land surface. Plant stomata function as a control interface for regulating photosynthetic uptake of CO2 and transpiration, strongly linked to plant productivity. Stomatal conductance is fundamental to larger-scale regional prediction of carbon-water cycles and their feedbacks to climate. The widely used Ball-Berry model coupled photosynthesis to a semi-empirical model of stomatal conductance. However large uncertainties remain in simulation of carbon assimilation rate in ecosystem and regional scales. The strong correlations of solar-induced fluorescence (SIF) and GPP have been demonstrated and provides an important opportunity to accurately monitor photosynthetic activity and water exchange. In this presentation, we compared both canopy-observed SIF and satellite-derived SIF with tower-based canopy stomatal conductance from hourly to 8-day scales in forest and cropland ecosystem. Using the model of stomatal conductance based on SIF, the transpiration was estimated at hourly and daily scales and compared with flux tower measurements. The results showed that the seasonal pattern of canopy stomatal conductance agreed better with SIF compared to NDVI and their relationship was higher during sunny days for forest ecosystem. Canopy stomatal conductance correlated with both tower-observed SIF and SIF from the Global Ozone Monitoring Experiment-2. Estimation of transpiration from SIF performed well in both forest and cropland ecosystem. This remotely sensed approaches from SIF for modelling stomatal conductance opens a new era to analysis and simulation of coupled carbon and water cycles under climate change.

  6. 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.

  7. Evaluating Uncertainties in Sap Flux Scaled Estimates of Forest Transpiration, Canopy Conductance and Photosynthesis

    Science.gov (United States)

    Ward, E. J.; Bell, D. M.; Clark, J. S.; Kim, H.; Oren, R.

    2009-12-01

    Thermal dissipation probes (TDPs) are a common method for estimating forest transpiration and canopy conductance from sap flux rates in trees, but their implementation is plagued by uncertainties arising from missing data and variability in the diameter and canopy position of trees, as well as sapwood conductivity within individual trees. Uncertainties in estimates of canopy conductance also translate into uncertainties in carbon assimilation in models such as the Canopy Conductance Constrained Carbon Assimilation (4CA) model that combine physiological and environmental data to estimate photosynthetic rates. We developed a method to propagate these uncertainties in the scaling and imputation of TDP data to estimates of canopy transpiration and conductance using a state-space Jarvis-type conductance model in a hierarchical Bayesian framework. This presentation will focus on the impact of these uncertainties on estimates of water and carbon fluxes using 4CA and data from the Duke Free Air Carbon Enrichment (FACE) project, which incorporates both elevated carbon dioxide and soil nitrogen treatments. We will also address the response of canopy conductance to vapor pressure deficit, incident radiation and soil moisture, as well as the effect of treatment-related stand structure differences in scaling TDP measurements. Preliminary results indicate that in 2006, a year of normal precipitation (1127 mm), canopy transpiration increased in elevated carbon dioxide ~8% on a ground area basis. In 2007, a year with a pronounced drought (800 mm precipitation), this increase was only present in the combined carbon dioxide and fertilization treatment. The seasonal dynamics of water and carbon fluxes will be discussed in detail.

  8. Evidence for soil water control on carbon and water dynamics in European forests during the extremely dry year: 2003

    DEFF Research Database (Denmark)

    Granier, A.; Reichstein, M.; Breda, N.

    2007-01-01

    stand to estimate the water balance terms: trees and understorey transpiration, rainfall interception, throughfall, drainage in the different soil layers and soil water content. This model calculated the onset date, duration and intensity of the soil water shortage (called water stress) using measured...... measured and modelled soil water content. Our analysis showed a wide spatial distribution of drought stress over Europe, with a maximum intensity within a large band extending from Portugal to NE Germany. Vapour fluxes in all the investigated sites were reduced by drought, due to stomatal closure, when...... the relative extractable water in soil (REW) dropped below ca. 0.4. Rainfall events during the drought, however, typically induced rapid restoration of vapour fluxes. Similar to the water vapour fluxes, the net ecosystem production decreased with increasing water stress at all the sites. Both gross primary...

  9. Cell wall composition contributes to the control of transpiration efficiency in Arabidopsis thaliana.

    Science.gov (United States)

    Liang, Yun-Kuan; Xie, Xiaodong; Lindsay, Shona E; Wang, Yi Bing; Masle, Josette; Williamson, Lisa; Leyser, Ottoline; Hetherington, Alistair M

    2010-11-01

    To identify loci in Arabidopsis involved in the control of transpirational water loss and transpiration efficiency (TE) we carried out an infrared thermal imaging-based screen. We report the identification of a new allele of the Arabidopsis CesA7 cellulose synthase locus designated AtCesA7(irx3-5) involved in the control of TE. Leaves of the AtCesA7(irx3-5) mutant are warmer than the wild type (WT). This is due to reduced stomatal pore widths brought about by guard cells that are significantly smaller than the WT. The xylem of the AtCesA7(irx3-5) mutant is also partially collapsed, and we suggest that the small guard cells in the mutant result from decreased water supply to the developing leaf. We used carbon isotope discrimination to show that TE is increased in AtCesA7(irx3-5) when compared with the WT. Our work identifies a new class of genes that affects TE and raises the possibility that other genes involved in cell wall biosynthesis will have an impact on water use efficiency. © 2010 The Authors. The Plant Journal © 2010 Blackwell Publishing Ltd.

  10. Scaling up and error analysis of transpiration for Populus euphratica in a desert riparian forest

    Science.gov (United States)

    Si, J.; Li, W.; Feng, Q.

    2013-12-01

    Water consumption information of the forest stand is the most important factor for regional water resources management. However, water consumption of individual trees are usually measured based on the limited sample trees , so, it is an important issue how to realize eventual scaling up of data from a series of sample trees to entire stand. Estimation of sap flow flux density (Fd) and stand sapwood area (AS-stand) are among the most critical factors for determining forest stand transpiration using sap flow measurement. To estimate Fd, the various links in sap flow technology have great impact on the measurement of sap flow, to estimate AS-stand, an appropriate indirect technique for measuring each tree sapwood area (AS-tree) is required, because it is impossible to measure the AS-tree of all trees in a forest stand. In this study, Fd was measured in 2 mature P. euphratic trees at several radial depths, 0~10, 10~30mm, using sap flow sensors with the heat ratio method, the relationship model between AS-tree and stem diameter (DBH), growth model of AS-tree were established, using investigative original data of DBH, tree-age, and AS-tree. The results revealed that it can achieve scaling up of transpiration from sample trees to entire forest stand using AS-tree and Fd, however, the transpiration of forest stand (E) will be overvalued by 12.6% if using Fd of 0~10mm, and it will be underestimated by 25.3% if using Fd of 10~30mm, it implied that major uncertainties in mean stand Fd estimations are caused by radial variations in Fd. E will be obviously overvalued when the AS-stand is constant, this result imply that it is the key to improve the prediction accuracy that how to simulate the AS-stand changes in the day scale; They also showed that the potential errors in transpiration with a sample size of approximately ≥30 were almost stable for P.euphrtica, this suggests that to make an allometric equation it might be necessary to sample at least 30 trees.

  11. 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.

    Science.gov (United States)

    López, Rosana; Brossa, Ricard; Gil, Luis; Pita, Pilar

    2015-01-01

    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 abscisic acid 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.

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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 ...

  17. Water-saving ground cover rice production system reduces net greenhouse gas fluxes in an annual rice-based cropping system

    Science.gov (United States)

    Yao, Z.; Du, Y.; Tao, Y.; Zheng, X.; Liu, C.; Lin, S.; Butterbach-Bahl, K.

    2014-11-01

    To safeguard food security and preserve precious water resources, the technology of water-saving ground cover rice production system (GCRPS) is being increasingly adopted for rice cultivation. However, changes in soil water status and temperature under GCRPS may affect soil biogeochemical processes that control the biosphere-atmosphere exchanges of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2). The overall goal of this study is to better understand how net ecosystem greenhouse gas exchanges (NEGE) and grain yields are affected by GCRPS in an annual rice-based cropping system. Our evaluation was based on measurements of the CH4 and N2O fluxes and soil heterotrophic respiration (CO2 emissions) over a complete year, and the estimated soil carbon sequestration intensity for six different fertilizer treatments for conventional paddy and GCRPS. The fertilizer treatments included urea application and no N fertilization for both conventional paddy (CUN and CNN) and GCRPS (GUN and GNN), and solely chicken manure (GCM) and combined urea and chicken manure applications (GUM) for GCRPS. Averaging across all the fertilizer treatments, GCRPS increased annual N2O emission and grain yield by 40 and 9%, respectively, and decreased annual CH4 emission by 69%, while GCRPS did not affect soil CO2 emissions relative to the conventional paddy. The annual direct emission factors of N2O were 4.01, 0.09 and 0.50% for GUN, GCM and GUM, respectively, and 1.52% for the conventional paddy (CUN). The annual soil carbon sequestration intensity under GCRPS was estimated to be an average of -1.33 Mg C ha-1 yr-1, which is approximately 44% higher than the conventional paddy. The annual NEGE were 10.80-11.02 Mg CO2-eq ha-1 yr-1 for the conventional paddy and 3.05-9.37 Mg CO2-eq ha-1 yr-1 for the GCRPS, suggesting the potential feasibility of GCRPS in reducing net greenhouse effects from rice cultivation. Using organic fertilizers for GCRPS considerably reduced annual emissions of CH4

  18. 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...

  19. Energy balance concept in the evaluation of water table management effects on corn growth: experimental investigation

    International Nuclear Information System (INIS)

    Kalita, P.K.; Kanwar, R.S.

    1992-01-01

    The effects of water table management practices (WTMP) on corn growth in 1989 and 1990 at two field sites, Ames and Ankeny, Iowa, were evaluated by calculating crop water stress index (CWSI) and monitoring plant physiological parameters during the growing seasons. Experiments were conducted on field lysimeters at the Ames site by maintaining water tables at 0.3-, 0.6-, and 0.9-m depths and in a subirrigation field at the Ankeny site with 0.2-, 0.3-, 0.6-, 0.9-, and 1.1-m water table depths, and periodically measuring leaf and air temperature, transpiration rate, stomatal conductance, and photosynthetically active radiation (PAR) using leaf chamber techniques. Net radiation of canopy was estimated using the leaf energy balance equation and leaf chamber measurements and then correlated with PAR. Analysis of data revealed that net radiation, leaf air temperature differential, transpiration rate, stomatal conductance, and CWSI were strongly related to WTMP during vegetative and flowering stages of corn growth. Excess water in the root zone with a water table depth of 0.2 m caused the maximum crop water stress and ceased crop growth. Both water and oxygen could be adequately maintained for favorable crop growth by adopting the best WTMP. Results indicate that plant physiological parameters and CWSI could be used to evaluate the effectiveness of WTMP and develop the best WTMP for corn growth in the humid region

  20. Transpirational water loss in invaded and restored semiarid riparian forests

    Science.gov (United States)

    Georgianne W. Moore; M. Keith Owens

    2011-01-01

    The invasive tree, Tamarix sp., was introduced to the United States in the 1800s to stabilize stream banks. The riparian ecosystem adjacent to the middle Rio Grande River in central NewMexico consists of mature cottonwood (Populus fremontii ) gallery forests with a dense Tamarix understory. We hypothesized that Populus would compensate for reduced competition by...

  1. INMARSAT-C SafetyNET

    Science.gov (United States)

    Tsunamis 406 EPIRB's National Weather Service Marine Forecasts INMARSAT-C SafetyNET Marine Forecast Offices greater danger near shore or any shallow waters? NATIONAL WEATHER SERVICE PRODUCTS VIA INMARSAT-C SafetyNET Inmarsat-C SafetyNET is an internationally adopted, automated satellite system for promulgating

  2. Fruit load governs transpiration of olive trees

    NARCIS (Netherlands)

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

    2016-01-01

    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

  3. Variation of Transpiration Efficiency in Sorghum

    Science.gov (United States)

    Declining freshwater resources, increasing population, and growing demand for biofuels pose new challenges for agriculture research. To meet these challenges, the concept “Blue Revolution” was proposed to improve water productivity in agriculture--“More Crop per Drop”. Sorghum is the fifth most imp...

  4. Genetic diversity in sorghum transpiration efficiency

    Science.gov (United States)

    Sorghum is the fifth most important grain crop and is becoming increasingly important as a biofuel feedstock due to its superior tolerance to water deficit stress. Sorghum is commonly grown under rain-fed conditions in the Southern Plains and other semi-arid regions in the world. Thus, its product...

  5. Variation in transpiration efficiency in sorghum

    Science.gov (United States)

    Declining freshwater resources, increasing population, and growing demand for biofuels pose new challenges for agriculture research. To meet these challenges, the concept “Blue Revolution” was proposed to improve water productivity in agriculture--“More Crop per Drop”. Sorghum is the fifth most imp...

  6. Carbon dioxide flux and net primary production of a boreal treed bog: Responses to warming and water-table-lowering simulations of climate change

    Science.gov (United States)

    Munir, T. M.; Perkins, M.; Kaing, E.; Strack, M.

    2015-02-01

    Midlatitude treed bogs represent significant carbon (C) stocks and are highly sensitive to global climate change. In a dry continental treed bog, we compared three sites: control, recent (1-3 years; experimental) and older drained (10-13 years), with water levels at 38, 74 and 120 cm below the surface, respectively. At each site we measured carbon dioxide (CO2) fluxes and estimated tree root respiration (Rr; across hummock-hollow microtopography of the forest floor) and net primary production (NPP) of trees during the growing seasons (May to October) of 2011-2013. The CO2-C balance was calculated by adding the net CO2 exchange of the forest floor (NEff-Rr) to the NPP of the trees. From cooler and wetter 2011 to the driest and the warmest 2013, the control site was a CO2-C sink of 92, 70 and 76 g m-2, the experimental site was a CO2-C source of 14, 57 and 135 g m-2, and the drained site was a progressively smaller source of 26, 23 and 13 g CO2-C m-2. The short-term drainage at the experimental site resulted in small changes in vegetation coverage and large net CO2 emissions at the microforms. In contrast, the longer-term drainage and deeper water level at the drained site resulted in the replacement of mosses with vascular plants (shrubs) on the hummocks and lichen in the hollows leading to the highest CO2 uptake at the drained hummocks and significant losses in the hollows. The tree NPP (including above- and below-ground growth and litter fall) in 2011 and 2012 was significantly higher at the drained site (92 and 83 g C m-2) than at the experimental (58 and 55 g C m-2) and control (52 and 46 g C m-2) sites. We also quantified the impact of climatic warming at all water table treatments by equipping additional plots with open-top chambers (OTCs) that caused a passive warming on average of ~ 1 °C and differential air warming of ~ 6 °C at midday full sun over the study years. Warming significantly enhanced shrub growth and the CO2 sink function of the drained

  7. Influence of irrigation and fertilization on transpiration and hydraulic properties of Populus deltoides.

    Energy Technology Data Exchange (ETDEWEB)

    Samuelson, Lisa, J.; Stokes, Thomas, A.; Coleman, Mark, D.

    2007-02-01

    Summary Long-term hydraulic acclimation to resource availability was explored in 3-year-bld Populus deltoides Bartr. ex Marsh. clones by examining transpiration. leaf-specific hydraulic conductance (GL), canopy stomatal conductance (Gs) and leaf to sapwood area ratio (AL:Asi)n response to imgation (13 and 551 mm year in addition to ambient precipitation) and fertilization (0 and 120 kg N ha-' year-'). Sap flow was measured continuously over one growing season with thermal dissipation probes. Fertilization had a greater effect on growth and hydraulic properties than imgation, and fertilization effects were independent of irrigation treatment. Transpiration on a ground area basis (E) ranged between 0.3 and 1.8 mm day-', and increased 66% and 90% in response to imgation and fertilization, respectively. Increases in GL, Gs at a reference vapor pressure deficit of 1 kPa, and transpiration per unit leaf areain response to increases in resource availability were associated with reductions in AL:As and consequently a minimal change in the water potential gradient from soil to leaf. Imgation and fertilization increased leaf area index similarly, from an average 1.16 in control stands to 1.45, but sapwood area was increased from 4.0 to 6.3 m ha-' by irrigation and from 3.7 to 6.7 m2 ha-' by fertilization. The balance between leaf area and sapwood area was important in understanding long-term hydraulic acclimation to resource availability and mechanisms controlling maximum productivity in Populus deltoides.

  8. 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 (Ptranspiration rate (Ptranspiration efficiency -related traits and yield in bread wheat, 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.

  9. Accuracy assessment of a net radiation and temperature index snowmelt model using ground observations of snow water equivalent in an alpine basin

    Science.gov (United States)

    Molotch, N. P.; Painter, T. H.; Bales, R. C.; Dozier, J.

    2003-04-01

    In this study, an accumulated net radiation / accumulated degree-day index snowmelt model was coupled with remotely sensed snow covered area (SCA) data to simulate snow cover depletion and reconstruct maximum snow water equivalent (SWE) in the 19.1-km2 Tokopah Basin of the Sierra Nevada, California. Simple net radiation snowmelt models are attractive for operational snowmelt runoff forecasts as they are computationally inexpensive and have low input requirements relative to physically based energy balance models. The objective of this research was to assess the accuracy of a simple net radiation snowmelt model in a topographically heterogeneous alpine environment. Previous applications of net radiation / temperature index snowmelt models have not been evaluated in alpine terrain with intensive field observations of SWE. Solar radiation data from two meteorological stations were distributed using the topographic radiation model TOPORAD. Relative humidity and temperature data were distributed based on the lapse rate calculated between three meteorological stations within the basin. Fractional SCA data from the Landsat Enhanced Thematic Mapper (5 acquisitions) and the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) (2 acquisitions) were used to derive daily SCA using a linear regression between acquisition dates. Grain size data from AVIRIS (4 acquisitions) were used to infer snow surface albedo and interpolated linearly with time to derive daily albedo values. Modeled daily snowmelt rates for each 30-m pixel were scaled by the SCA and integrated over the snowmelt season to obtain estimates of maximum SWE accumulation. Snow surveys consisting of an average of 335 depth measurements and 53 density measurements during April, May and June, 1997 were interpolated using a regression tree / co-krig model, with independent variables of average incoming solar radiation, elevation, slope and maximum upwind slope. The basin was clustered into 7 elevation / average

  10. Quantitative description of the relation between protein net charge and protein adsorption to air-water interfaces

    NARCIS (Netherlands)

    Wierenga, P.A.; Meinders, M.B.J.; Egmond, M.R.; Voragen, A.G.J.; Jongh, H.H.J.de

    2005-01-01

    In this study a set of chemically engineered variants of ovalbumin was produced to study the effects of electrostatic charge on the adsorption kinetics and resulting surface pressure at the air-water interface. The modification itself was based on the coupling of succinic anhydride to lysine

  11. Individual variation of sap-flow rate in large pine and spruce trees and stand transpiration: a pilot study at the central NOPEX site

    Science.gov (United States)

    Čermák, J.; Cienciala, E.; Kučera, J.; Lindroth, A.; Bednářová, E.

    1995-06-01

    Transpiration in a mixed old stand of sub-boreal forest in the Norunda region (central Sweden) was estimated on the basis of direct measurement of sap flow rate in 24 large Scots pine and Norway spruce trees in July and August 1993. Sap flow rate was measured using the trunk tissue heat balance method based on internal (electric) heating and sensing of temperature. Transpiration was only 0.7 mm day -1 in a relatively dry period in July (i.e. about 20% of potential evaporation) and substantially higher after a rainy period in August. The error of the estimates of transpiration was higher during a dry period (about 13% and 22% in pine and spruce, respectively) and significantly lower (about 9% in both species) during a period of sufficient water supply. Shallow-rooted spruce trees responded much faster to precipitation than deeply rooted pines.

  12. First testing of an AUV mission planning and guidance system for water quality monitoring and fish behavior observation in net cage fish farming

    Directory of Open Access Journals (Sweden)

    D. Karimanzira

    2014-12-01

    Full Text Available Recently, underwater vehicles have become low cost, reliable and affordable platforms for performing various underwater tasks. While many aquaculture systems are closed with no harmful output, open net cage fish farms and land-based fish farms can discharge significant amounts of wastewater containing nutrients, chemicals, and pharmaceuticals that impact on the surrounding environment. Although aquaculture development has often occurred outside a regulatory framework, government oversight is increasingly common at both the seafood quality control level, and at baseline initiatives addressing the basic problem of pollution generated by culture operations, e.g. the European marine and maritime directives. This requires regular, sustainable and cost-effective monitoring of the water quality. Such monitoring needs devices to detect the water quality in a large sea area at different depths in real time. This paper presents a concept for a guidance system for a carrier (an autonomous underwater vehicle of such devices for the automated detection and analysis of water quality parameters.

  13. Strobilurin fungicides induce changes in photosynthetic gas exchange that do not improve water use efficiency of plants grown under conditions of water stress.

    Science.gov (United States)

    Nason, Mark A; Farrar, John; Bartlett, David

    2007-12-01

    The effects of five strobilurin (beta-methoxyacrylate) fungicides and one triazole fungicide on the physiological parameters of well-watered or water-stressed wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and soya (Glycine max Merr.) plants were compared. Water use efficiency (WUE) (the ratio of rate of transpiration, E, to net rate of photosynthesis, A(n)) of well-watered wheat plants was improved slightly by strobilurin fungicides, but was reduced in water-stressed plants, so there is limited scope for using strobilurins to improve the water status of crops grown under conditions of drought. The different strobilurin fungicides had similar effects on plant physiology but differed in persistence and potency. When applied to whole plants using a spray gun, they reduced the conductance of water through the epidermis (stomatal and cuticular transpiration), g(sw), of leaves. Concomitantly, leaves of treated plants had a lower rate of transpiration, E, a lower intercellular carbon dioxide concentration, c(i), and a lower net rate of photosynthesis, A(n), compared with leaves of control plants or plants treated with the triazole. The mechanism for the photosynthetic effects is not known, but it is hypothesised that they are caused either by strobilurin fungicides acting directly on ATP production in guard cell mitochondria or by stomata responding to strobilurin-induced changes in mesophyll photosynthesis. The latter may be important since, for leaves of soya plants, the chlorophyll fluorescence parameter F(v)/F(m) (an indication of the potential quantum efficiency of PSII photochemistry) was reduced by strobilurin fungicides. It is likely that the response of stomata to strobilurin fungicides is complex, and further research is required to elucidate the different biochemical pathways involved. Copyright (c) 2007 Society of Chemical Industry.

  14. Mathematical Modeling of Dual Intake Transparent Transpired Solar Collector

    Directory of Open Access Journals (Sweden)

    Thomas Semenou

    2015-01-01

    Full Text Available Nowadays, in several types of commercial or institutional buildings, a significant rise of transpired solar collectors used to preheat the fresh air of the building can be observed. Nevertheless, when the air mass flow rate is low, the collector efficiency collapses and a large amount of energy remains unused. This paper presents a simple yet effective mathematical model of a transparent transpired solar collector (TTC with dual intake in order to remove stagnation problems in the plenum and ensure a better thermal efficiency and more heat recovery. A thermal model and a pressure loss model were developed. Then, the combined model was validated with experimental data from the Solar Rating and Certification Corporation (SRCC. The results show that the collector efficiency can be up to 70% and even 80% regardless of operating conditions. The temperature gain is able to reach 20°K when the solar irradiation is high.

  15. Size-mediated tree transpiration along soil drainage gradients in a boreal black spruce forest wildfire chronosequence.

    Science.gov (United States)

    Angstmann, J L; Ewers, B E; Kwon, H

    2012-05-01

    Boreal forests are crucial to climate change predictions because of their large land area and ability to sequester and store carbon, which is controlled by water availability. Heterogeneity of these forests is predicted to increase with climate change through more frequent wildfires, warmer, longer growing seasons and potential drainage of forested wetlands. This study aims at quantifying controls over tree transpiration with drainage condition, stand age and species in a central Canadian black spruce boreal forest. Heat dissipation sensors were installed in 2007 and data were collected through 2008 on 118 trees (69 Picea mariana (Mill.) Britton, Sterns & Poggenb. (black spruce), 25 Populus tremuloides Michx. (trembling aspen), 19 Pinus banksiana Lamb. (jack pine), 3 Larix laricina (Du Roi) K. Koch (tamarack) and 2 Salix spp. (willow)) at four stand ages (18, 43, 77 and 157 years old) each containing a well- and poorly-drained stand. Transpiration estimates from sap flux were expressed per unit xylem area, J(S), per unit ground area, E(C) and per unit leaf area, E(L), using sapwood (A(S)) and leaf (A(L)) area calculated from stand- and species-specific allometry. Soil drainage differences in transpiration were variable; only the 43- and 157-year-old poorly-drained stands had ∼ 50% higher total stand E(C) than well-drained locations. Total stand E(C) tended to decrease with stand age after an initial increase between the 18- and 43-year-old stands. Soil drainage differences in transpiration were controlled primarily by short-term physiological drivers such as vapor pressure deficit and soil moisture whereas stand age differences were controlled by successional species shifts and changes in tree size (i.e., A(S)). Future predictions of boreal climate change must include stand age, species and soil drainage heterogeneity to avoid biased estimates of forest water loss and latent energy exchanges.

  16. 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

  17. Seasonal photosynthetic gas exchange and water-use efficiency in a constitutive CAM plant, the giant saguaro cactus (Carnegiea gigantea).

    Science.gov (United States)

    Bronson, Dustin R; English, Nathan B; Dettman, David L; Williams, David G

    2011-11-01

    Crassulacean acid metabolism (CAM) and the capacity to store large quantities of water are thought to confer high water use efficiency (WUE) and survival of succulent plants in warm desert environments. Yet the highly variable precipitation, temperature and humidity conditions in these environments likely have unique impacts on underlying processes regulating photosynthetic gas exchange and WUE, limiting our ability to predict growth and survival responses of desert CAM plants to climate change. We monitored net CO(2) assimilation (A(net)), stomatal conductance (g(s)), and transpiration (E) rates periodically over 2 years in a natural population of the giant columnar cactus Carnegiea gigantea (saguaro) near Tucson, Arizona USA to investigate environmental and physiological controls over carbon gain and water loss in this ecologically important plant. We hypothesized that seasonal changes in daily integrated water use efficiency (WUE(day)) in this constitutive CAM species would be driven largely by stomatal regulation of nighttime transpiration and CO(2) uptake responding to shifts in nighttime air temperature and humidity. The lowest WUE(day) occurred during time periods with extreme high and low air vapor pressure deficit (D(a)). The diurnal with the highest D(a) had low WUE(day) due to minimal net carbon gain across the 24 h period. Low WUE(day) was also observed under conditions of low D(a); however, it was due to significant transpiration losses. Gas exchange measurements on potted saguaro plants exposed to experimental changes in D(a) confirmed the relationship between D(a) and g(s). Our results suggest that climatic changes involving shifts in air temperature and humidity will have large impacts on the water and carbon economy of the giant saguaro and potentially other succulent CAM plants of warm desert environments.

  18. Age-related effects on leaf area/sapwood area relationships, canopy transpiration and carbon gain of Norway spruce stands (Picea abies) in the Fichtelgebirge, Germany.

    Science.gov (United States)

    Köstner, B; Falge, E; Tenhunen, J D

    2002-06-01

    Stand age is an important structural determinant of canopy transpiration (E(c)) and carbon gain. Another more functional parameter of forest structure is the leaf area/sapwood area relationship, A(L)/A(S), which changes with site conditions and has been used to estimate leaf area index of forest canopies. The interpretation of age-related changes in A(L)/A(S) and the question of how A(L)/A(S) is related to forest functions are of current interest because they may help to explain forest canopy fluxes and growth. We conducted studies in mature stands of Picea abies (L.) Karst. varying in age from 40 to 140 years, in tree density from 1680 to 320 trees ha(-1), and in tree height from 15 to 30 m. Structural parameters were measured by biomass harvests of individual trees and stand biometry. We estimated E(c) from scaled-up xylem sap flux of trees, and canopy-level fluxes were predicted by a three-dimensional microclimate and gas exchange model (STANDFLUX). In contrast to pine species, A(L)/A(S) of P. abies increased with stand age from 0.26 to 0.48 m(2) cm(-2). Agreement between E(c) derived from scaled-up sap flux and modeled canopy transpiration was obtained with the same parameterization of needle physiology independent of stand age. Reduced light interception per leaf area and, as a consequence, reductions in net canopy photosynthesis (A(c)), canopy conductance (g(c)) and E(c) were predicted by the model in the older stands. Seasonal water-use efficiency (WUE = A(c)/E(c)), derived from scaled-up sap flux and stem growth as well as from model simulation, declined with increasing A(L)/A(S) and stand age. Based on the different behavior of age-related A(L)/A(S) in Norway spruce stands compared with other tree species, we conclude that WUE rather than A(L)/A(S) could represent a common age-related property of all species. We also conclude that, in addition to hydraulic limitations reducing carbon gain in old stands, a functional change in A(L)/A(S) that is related to

  19. Transpiration and Groundwater Uptake Dynamics of Pinus Brutia on a Fractured Mediterranean Mountain Slope during Two Hydrologically Contrasting Years

    Science.gov (United States)

    Eliades, Marinos; Bruggeman, Adriana; Lubczynski, Maciek; Christou, Andreas; Camera, Corrado; Djuma, Hakan

    2017-04-01

    Semi-arid environments tend to have extreme temporal variability in rainfall, resulting in extended periods with little to no precipitation. The mountainous topography is characterized by steep slopes, often leading to shallow soil layers with limited water storage capacity. Tree species survive in these environments by developing various adaptation mechanisms to access water. The main objective of this study is to examine the differences of two hydrologically contrasting years on the transpiration and groundwater uptake dynamics of Pinus brutia trees. We selected four trees for sap flow monitoring in an 8966-m2 fenced area of Pinus brutia forest. The site is located at 620 m elevation, on the northern foothills of the Troodos mountains in Cyprus. The slope of the site ranges between 0 and 82%. The average daily minimum temperature is 5 0C in January and the average daily maximum temperature is 35 oC in August. The mean annual rainfall is 425 mm. Monitoring started on 1 January 2015 and is ongoing. We measured soil depth in a 1-m grid around each of the selected trees for monitoring. We processed soil depths in ArcGIS software (ESRI) to create a soil depth map. We used a Total Station and a differential GPS for the creation of a high resolution DEM of the area covering the selected trees. We installed seventeen soil moisture sensors at 12-cm depth and two at 30-cm depth, where the soil was deeper than 24 cm. We randomly installed 28 metric manual rain gauges under the trees' canopy to measure throughfall. For stemflow we installed a plastic tube around each tree trunk and connected it to a manual rain gauge. We used sap flow heat ratio method (HRM) instruments to determine sap flow rates of the Pinus brutia. Hourly meteorological conditions were observed by an automatic meteorological station. Here we present the results of the January to October periods, in order to have comparable results for the two contrasting years. During the wet year of 2015, we measured 439

  20. Desempenho do modelo AcquaNetXL na alocação de água em sistemas de recursos hídricos complexos Performance of the model called AcquaNetXL in the allocation of water in complex water resource systems

    Directory of Open Access Journals (Sweden)

    André Schardong

    2009-01-01

    Full Text Available Este artigo apresenta uma ferramenta para análise de sistemas complexos de recursos hídricos denominada AcquaNetXL, que foi desenvolvida no formato de planilha eletrônica, na qual foram incorporados dois modelos de otimização, um linear e outro não linear. Essa ferramenta mantém os conceitos e os atributos de um sistema de suporte a decisão, ou seja, possui as características de estreitar a comunicação entre o usuário e o computador, de facilitar o entendimento, a formulação do problema, a interpretação dos resultados de análise e auxiliar no processo de tomada de decisão, tornando-o mais ordenado, objetivo e transparente. O desempenho do algoritmo utilizado na solução dos problemas de alocação de água foi satisfatório, especialmente para o modelo linear.This article presents a tool for the allocation analysis of complex systems of water resources, called AcquaNetXL, developed in the form of spreadsheet in which a model of linear optimization and another nonlinear were incorporated. The AcquaNetXL keeps the concepts and attributes of a decision support system. In other words, it straightens out the communication between the user and the computer, facilitates the understanding and the formulation of the problem, the interpretation of the results and it also gives a support in the process of decision making, turning it into a clear and organized process. The performance of the algorithms used for solving the problems of water allocation was satisfactory especially for the linear model.

  1. Abscisic acid-dependent changes in transpiration rate with SO/sub 2/ fumigation and the effects of sulfite and pH on stomatal aperture

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, N.; Maruta, I.; Sugahara, K.

    1980-01-01

    Transpiration rate of rice plants which contained extremely large amounts of abscisic acid (ABA) decreased rapidly with 2.0 ppm SO/sub 2/ fumigation, reached 20% of the initial level after 5 min exposure, then recovered slightly and thereafter remained constant. SO/sub 2/ fumigation of alday and tobacco (Nicotiana tabacum L. Samsun) which have a lower ABA content showed a 50% decrease in transpiration rate. Similarly, rates for wheat and tobacco (N. tabacum L. Samsun NN) which contained even smaller amounts of ABA than alday and tobacco (Samsun) decreased by 35 and 45%, respectively, 30 min after the beginning of the fumigation. In the cases of broad bean and tobacco (N. glutinosa L.) with low ABA contents, the rates slightly increased immediately after the start of the fumigation and began to decrease gradually 20 and 40 min later, respectively. The transpiration rates of corn and sorghum, in spite of their extremely low ABA contents, decreased significantly with SO/sub 2/ fumigation and reached 65 and 50% of the initial levels after 20 and 40 min exposure, respectively. Foliar application of 0.04 N HCl to peanut leaves remarkably depressed the transpiration rate, while the application of 0.04 M Na/sub 2/SO/sub 3/ decreased the rate only to the same level as water treatment. Foliar application of either HCl or Na/sub 2/SO/sub 3/ to radish leaves exerted no change in the transpiration rate. When 3 X 10/sup -4/ M ABA was applied to radish leaves prior to HCl and Na/sub 2/SO/sub 3/ treatment, the transpiration rate of radish was decreased by HCl application, but not by Na/sub 2/SO/sub 3/.

  2. 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

  3. 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

  4. Uptake of 32P and 86Rb as influenced by temperature, transpiration suppress and shading treatment in rice plants

    Energy Technology Data Exchange (ETDEWEB)

    Lee, G. B.; Hong, Y. P.; Im, J. N.; Chung, K. W.

    1989-07-01

    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.

  5. The alpha-subunit of the Arabidopsis heterotrimeric G protein, GPA1, is a regulator of transpiration efficiency.

    Science.gov (United States)

    Nilson, Sarah E; Assmann, Sarah M

    2010-04-01

    Land plants must balance CO2 assimilation with transpiration in order to minimize drought stress and maximize their reproductive success. The ratio of assimilation to transpiration is called transpiration efficiency (TE). TE is under genetic control, although only one specific gene, ERECTA, has been shown to regulate TE. We have found that the alpha-subunit of the heterotrimeric G protein in Arabidopsis (Arabidopsis thaliana), GPA1, is a regulator of TE. gpa1 mutants, despite having guard cells that are hyposensitive to abscisic acid-induced inhibition of stomatal opening, have increased TE under ample water and drought stress conditions and when treated with exogenous abscisic acid. Leaf-level gas-exchange analysis shows that gpa1 mutants have wild-type assimilation versus internal CO2 concentration responses but exhibit reduced stomatal conductance compared with ecotype Columbia at ambient and below-ambient internal CO2 concentrations. The increased TE and reduced whole leaf stomatal conductance of gpa1 can be primarily attributed to stomatal density, which is reduced in gpa1 mutants. GPA1 regulates stomatal density via the control of epidermal cell size and stomata formation. GPA1 promoter::beta-glucuronidase lines indicate that the GPA1 promoter is active in the stomatal cell lineage, further supporting a function for GPA1 in stomatal development in true leaves.

  6. Canopy transpiration of pure and mixed forest stands with variable abundance of European beech

    Science.gov (United States)

    Gebauer, Tobias; Horna, Viviana; Leuschner, Christoph

    2012-06-01

    SummaryThe importance of tree species identity and diversity for biogeochemical cycles in forests is not well understood. In the past, forestry has widely converted mixed forests to pure stands while contemporary forest policy often prefers mixed stands again. However, the hydrological consequences of these changes remain unclear. We tested the hypotheses (i) that significant differences in water use per ground area exist among the tree species of temperate mixed forests and that these differences are more relevant for the amount of stand-level canopy transpiration (Ec) than putative complementarity effects of tree water use, and (ii) that the seasonal patterns of Ec in mixed stands are significantly influenced by the identity of the present tree species. We measured xylem sap flux during 2005 (average precipitation) and 2006 (relatively dry) synchronously in three nearby old-growth forest stands on similar soil differing in the abundance of European beech (pure beech stand, 3-species stand with 70% beech, 5-species stand with sapwood area basis, reflecting a considerable variation in hydraulic architecture and leaf conductance regulation among the co-existing species. Moreover, transpiration per crown projection area (ECA) also differed up to 5-fold among the different species in the mixed stands, probably reflecting contrasting sapwood/crown area ratios. We conclude that Ec is not principally higher in mixed forests than in pure beech stands. However, tree species-specific traits have an important influence on the height of Ec and affect its seasonal variation. Species with a relatively high ECA (notably Tilia) may exhaust soil water reserves early in summer, thereby increasing drought stress in dry years and possibly reducing ecosystem stability in mixed forests.

  7. 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

  8. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt

    1987-01-01

    The author describes a Petri net model, called coloured Petri nets (CP-nets), by means of which it is possible to describe large systems without having to cope with unnecessary details. The author introduces CP-nets and provide a first impression of their modeling power and the suitability...

  9. Learning Visual Basic NET

    CERN Document Server

    Liberty, Jesse

    2009-01-01

    Learning Visual Basic .NET is a complete introduction to VB.NET and object-oriented programming. By using hundreds of examples, this book demonstrates how to develop various kinds of applications--including those that work with databases--and web services. Learning Visual Basic .NET will help you build a solid foundation in .NET.

  10. Modelling soil temperature and moisture and corresponding seasonality of photosynthesis and transpiration in a boreal spruce ecosystem

    Science.gov (United States)

    Wu, S. H.; Jansson, P.-E.

    2013-02-01

    Recovery of photosynthesis and transpiration is strongly restricted by low temperatures in air and/or soil during the transition period from winter to spring in boreal zones. The extent to which air temperature (Ta) and soil temperature (Ts) influence the seasonality of photosynthesis and transpiration of a boreal spruce ecosystem was investigated using a process-based ecosystem model (CoupModel) together with eddy covariance (EC) data from one eddy flux tower and nearby soil measurements at Knottåsen, Sweden. A Monte Carlo-based uncertainty method (GLUE) provided prior and posterior distributions of simulations representing a wide range of soil conditions and performance indicators. The simulated results showed sufficient flexibility to predict the measured cold and warm Ts in the moist and dry plots around the eddy flux tower. Moreover, the model presented a general ability to describe both biotic and abiotic processes for the Norway spruce stand. The dynamics of sensible heat fluxes were well described by the corresponding latent heat fluxes and net ecosystem exchange of CO2. The parameter ranges obtained are probably valid to represent regional characteristics of boreal conifer forests, but were not easy to constrain to a smaller range than that produced by the assumed prior distributions. Finally, neglecting the soil temperature response function resulted in fewer behavioural models and probably more compensatory errors in other response functions for regulating the seasonality of ecosystem fluxes.

  11. Genetic variation in transpiration efficiency and relationships between whole plant and leaf gas exchange measurements in Saccharum spp. and related germplasm.

    Science.gov (United States)

    Jackson, Phillip; Basnayake, Jaya; Inman-Bamber, Geoff; Lakshmanan, Prakash; Natarajan, Sijesh; Stokes, Chris

    2016-02-01

    Fifty-one genotypes of sugarcane (Saccharum spp.) or closely related germplasm were evaluated in a pot experiment to examine genetic variation in transpiration efficiency. Significant variation in whole plant transpiration efficiency was observed, with the difference between lowest and highest genotypes being about 40% of the mean. Leaf gas exchange measurements were made across a wide range of conditions. There was significant genetic variation in intrinsic transpiration efficiency at a leaf level as measured by leaf internal CO2 (Ci) levels. Significant genetic variation in Ci was also observed within subsets of data representing narrow ranges of stomatal conductance. Ci had a low broad sense heritability (Hb = 0.11) on the basis of single measurements made at particular dates, because of high error variation and genotype × date interaction, but broad sense heritability for mean Ci across all dates was high (Hb = 0.81) because of the large number of measurements taken at different dates. Ci levels among genotypes at mid-range levels of conductance had a strong genetic correlation (-0.92 ± 0.30) with whole plant transpiration efficiency but genetic correlations between Ci and whole plant transpiration efficiency were weaker or not significant at higher and lower levels of conductance. Reduced Ci levels at any given level of conductance may result in improved yields in water-limited environments without trade-offs in rates of water use and growth. Targeted selection and improvement of lowered Ci per unit conductance via breeding may provide longer-term benefits for water-limited environments but the challenge will be to identify a low-cost screening methodology. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  12. Slug flow in horizontal pipes with transpiration at the wall

    Science.gov (United States)

    Loureiro, J. B. R.; Silva Freire, A. P.

    2011-12-01

    The present work investigates the behaviour of slug flows in horizontal pipes with a permeable wall. Measurements of pressure drop and of local velocity are given for nine different flow conditions. The liquid phase velocity was measured with laser Doppler anemometry. Single-phase data are compared with the results of other authors. The influence of flow transpiration and of roughness on the features of slug flows is shown to be pronounced. A Shadow Sizer system coupled with Particle Image Velocimetry is used to account for the properties of the slug cell.

  13. Slug flow in horizontal pipes with transpiration at the wall

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, J B R; Freire, A P Silva, E-mail: jbrloureiro@mecanica.ufrj.br [Mechanical Engineering Program, Federal University of Rio de Janeiro (COPPE/UFRJ), C.P. 68503, 21.941-972, Rio de Janeiro, RJ (Brazil)

    2011-12-22

    The present work investigates the behaviour of slug flows in horizontal pipes with a permeable wall. Measurements of pressure drop and of local velocity are given for nine different flow conditions. The liquid phase velocity was measured with laser Doppler anemometry. Single-phase data are compared with the results of other authors. The influence of flow transpiration and of roughness on the features of slug flows is shown to be pronounced. A Shadow Sizer system coupled with Particle Image Velocimetry is used to account for the properties of the slug cell.

  14. Slug flow in horizontal pipes with transpiration at the wall

    International Nuclear Information System (INIS)

    Loureiro, J B R; Freire, A P Silva

    2011-01-01

    The present work investigates the behaviour of slug flows in horizontal pipes with a permeable wall. Measurements of pressure drop and of local velocity are given for nine different flow conditions. The liquid phase velocity was measured with laser Doppler anemometry. Single-phase data are compared with the results of other authors. The influence of flow transpiration and of roughness on the features of slug flows is shown to be pronounced. A Shadow Sizer system coupled with Particle Image Velocimetry is used to account for the properties of the slug cell.

  15. 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...

  16. 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...

  17. The annual cycle of nitrate and net community production in surface waters of the Southern Ocean observed with SOCCOM profiling floats

    Science.gov (United States)

    Johnson, K. S.; Plant, J. N.; Sakamoto, C.; Coletti, L. J.; Sarmiento, J. L.; Riser, S.; Talley, L. D.

    2016-12-01

    Sixty profiling floats with ISUS and SUNA nitrate sensors have been deployed in the Southern Ocean (south of 30 degrees S) as part of the SOCCOM (Southern Ocean Carbon and Climate Observations and Modeling) program and earlier efforts. These floats have produced detailed records of the annual cycle of nitrate concentration throughout the region from the surface to depths near 2000 m. In surface waters, there are clear cycles in nitrate concentration that result from uptake of nitrate during austral spring and summer. These changes in nitrate concentration were used to compute the annual net community production over this region. NCP was computed using a simplified version of the approach detailed by Plant et al. (2016, Global Biogeochemical Cycles, 30, 859-879, DOI: 10.1002/2015GB005349). At the time the abstract was written 41 complete annual cycles were available from floats deployed before the austral summer of 2015/2016. After filtering the data to remove floats that crossed distinct frontal boundaries, floats with other anomalies, and floats in sub-tropical waters, 23 cycles were available. A preliminary assessment of the data yields an NCP of 2.8 +/- 0.95 (1 SD) mol C/m2/y after integrating to 100 m depth and converting nitrate uptake to carbon using the Redfield ratio. This preliminary assessment ignores vertical transport across the nitracline and is, therefore, a minimum estimate. The number of cycles available for analysis will increase rapidly, as 32 of the floats were deployed in the austral summer of 2015/2016 and have not yet been analyzed.

  18. Net global warming potential and greenhouse gas intensity as affected by different water management strategies in Chinese double rice-cropping systems.

    Science.gov (United States)

    Wu, Xiaohong; Wang, Wei; Xie, Xiaoli; Yin, Chunmei; Hou, Haijun; Yan, Wende; Wang, Guangjun

    2018-01-15

    This study provides a complete account of global warming potential (GWP) and greenhouse gas intensity (GHGI) in relation to a long-term water management experiment in Chinese double-rice cropping systems. The three strategies of water management comprised continuous (year-round) flooding (CF), flooding during the rice season but with drainage during the midseason and harvest time (F-D-F), and irrigation only for flooding during transplanting and the tillering stage (F-RF). The CH 4 and N 2 O fluxes were measured with the static chamber method. Soil organic carbon (SOC) sequestration rates were estimated based on the changes in the carbon stocks during 1998-2014. Longer periods of soil flooding led to increased CH 4 emissions, reduced N 2 O emissions, and enhanced SOC sequestration. The net GWPs were 22,497, 8,895, and 1,646 kg CO 2 -equivalent ha -1 yr -1 for the CF, F-D-F, and F-RF, respectively. The annual rice grain yields were comparable between the F-D-F and CF, but were reduced significantly (by 13%) in the F-RF. The GHGIs were 2.07, 0.87, and 0.18 kg CO 2 -equivalent kg -1 grain yr -1 for the CF, F-D-F, and F-RF, respectively. These results suggest that F-D-F could be used to maintain the grain yields and simultaneously mitigate the climatic impact of double rice-cropping systems.

  19. Hydraulic lift through transpiration suppression in shrubs from two arid ecosystems: patterns and control mechanisms.

    Science.gov (United States)

    Prieto, Iván; Martínez-Tillería, Karina; Martínez-Manchego, Luis; Montecinos, Sonia; Pugnaire, Francisco I; Squeo, Francisco A

    2010-08-01

    Hydraulic lift (HL) is the passive movement of water through the roots from deep wet to dry shallow soil layers when stomata are closed. HL has been shown in different ecosystems and species, and it depends on plant physiology and soil properties. In this study we explored HL patterns in several arid land shrubs, and developed a simple model to simulate the temporal evolution and magnitude of HL during a soil drying cycle under relatively stable climatic conditions. This model was then used to evaluate the influence of soil texture on the quantity of water lifted by shrubs in different soil types. We conducted transpiration suppression experiments during spring 2005 in Chile and spring 2008 in Spain on five shrub species that performed HL, Flourensia thurifera, Senna cumingii and Pleocarphus revolutus (Chile), Retama sphaerocarpa and Artemisia barrelieri (Spain). Shrubs were covered with a black, opaque plastic fabric for a period of 48-72 h, and soil water potential was recorded at different depths under the shrubs. While the shrubs remained covered, water potential continuously increased in shallow soil layers until the cover was removed. The model output indicated that the amount of water lifted by shrubs is heavily dependent on soil texture, as shrubs growing in loamy soils redistributed up to 3.6 times more water than shrubs growing on sandy soils. This could be an important consideration for species growing in soils with different textures, as their ability to perform HL would be context dependent.

  20. Transpiration and stomatal conductance in a young secondary tropical montane forest: contrasts between native trees and invasive understorey shrubs.

    Science.gov (United States)

    Ghimire, Chandra Prasad; Bruijnzeel, L Adrian; Lubczynski, Maciek W; Zwartendijk, Bob W; Odongo, Vincent Omondi; Ravelona, Maafaka; van Meerveld, H J Ilja

    2018-04-21

    It has been suggested that vigorous secondary tropical forests can have very high transpiration rates, but sap flow and stomatal conductance dynamics of trees and shrubs in these forests are understudied. In an effort to address this knowledge gap, sap flow (thermal dissipation method, 12 trees) and stomatal conductance (porometry, six trees) were measured for young (5-7 years) Psiadia altissima (DC.) Drake trees, a widely occurring species dominating young regrowth following abandonment of swidden agriculture in upland eastern Madagascar. In addition, stomatal conductance (gs) was determined for three individuals of two locally common invasive shrubs (Lantana camara L. and Rubus moluccanus L.) during three periods with contrasting soil moisture conditions. Values of gs for the three investigated species were significantly higher and more sensitive to climatic conditions during the wet period compared with the dry period. Further, gs of the understorey shrubs was much more sensitive to soil moisture content than that of the trees. Tree transpiration rates (Ec) were relatively stable during the dry season and were only affected somewhat by soil water content at the end of the dry season, suggesting the trees had continued access to soil water despite drying out of the topsoil. The Ec exhibited a plateau-shaped relation with vapour pressure deficit (VPD), which was attributed to stomatal closure at high VPD. Vapour pressure deficit was the major driver of variation in Ec, during both the wet and the dry season. Overall water use of the trees was modest, possibly reflecting low site fertility after three swidden cultivation cycles. The observed contrast in gs response to soil water and climatic conditions for the trees and shrubs underscores the need to take root distributions into account when modelling transpiration from regenerating tropical forests.

  1. 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

  2. Transpiration cooling assisted ablative thermal protection of aerospace substructures

    International Nuclear Information System (INIS)

    Khan, M.B.; Iqbal, N.; Haider, Z.

    2009-01-01

    Ablatives are heat-shielding materials used to protect aerospace substructures. These materials are sacrificial in nature and provide protection primarily through the large endothermic transformation during exposure to hyper thermal environment such as encountered in re-entry modules. The performance of certain ablatives was reported in terms of their TGA/DTA in Advanced Materials-97 (pp 57-65). The focus of this earlier research resided in the consolidation of interface between the refractory inclusion and the host polymeric matrix to improve thermal resistance. In the present work we explore the scope of transpiration cooling in ablative performance through flash evaporation of liquid incorporated in the host EPDM (Ethylene Propylene Diene Monomer) matrix. The compression-molded specimens were exposed separately to plasma flame (15000 C) and oxyacetylene torch (3000 C) and the back face transient temperature is recorded in situ employing a thermocouple/data logger system. Both head on impingement (HOI) and parallel flow (PF) through a central cavity in the ablator were used. It is observed that transpiration cooling is effective and yields (a) rapid thermal equilibrium in the specimen, (b) lower back face temperature and (c) lower ablation rate, compared to conventional ablatives. SEM/EDS analysis is presented to amplify the point. (author)

  3. Difference in leaf water use efficiency/photosynthetic nitrogen use efficiency of Bt-cotton and its conventional peer.

    Science.gov (United States)

    Guo, Ruqing; Sun, Shucun; Liu, Biao

    2016-09-15

    This study is to test the effects of Bt gene introduction on the foliar water/nitrogen use efficiency in cotton. We measured leaf stomatal conductance, photosynthetic rate, and transpiration rate under light saturation condition at different stages of a conventional cultivar (zhongmian no. 16) and its counterpart Bt cultivar (zhongmian no. 30) that were cultured on three levels of fertilization, based on which leaf instantaneous water use efficiency was derived. Leaf nitrogen concentration was measured to calculate leaf photosynthetic nitrogen use efficiency, and leaf δ(13)C was used to characterize long term water use efficiency. Bt cultivar was found to have lower stomatal conductance, net photosynthetic rates and transpiration rates, but higher instantaneous and long time water use efficiency. In addition, foliar nitrogen concentration was found to be higher but net photosynthetic rate was lower in the mature leaves of Bt cultivar, which led to lower photosynthetic nitrogen use efficiency. This might result from the significant decrease of photosynthetic rate due to the decrease of stomatal conductance. In conclusion, our findings show that the introduction of Bt gene should significantly increase foliar water use efficiency but decrease leaf nitrogen use efficiency in cotton under no selective pressure.

  4. Influence of a net cage tilapia culture on the water quality of the Nova Avanhandava reservoir, São Paulo State, Brazil - doi: 10.4025/actascibiolsci.v34i3.7298

    Directory of Open Access Journals (Sweden)

    André Luiz Scarano Camargo

    2012-06-01

    Full Text Available In order to understand the influence of a net cage tilapia culture on the environment, water quality parameters were investigated during the period between December, 2005 and November, 2007. Three sampling stations were established in the reservoir of Nova Avanhandava (Zacarias, São Paulo State as follows: upstream of net cage area (P1, in the rearing place (P2 and downstream of net cage area (P3. The mean values of the parameters examined in the water sampling stations were within the standards of water quality recommended by resolution no. 357/2005 of the Conselho Nacional do Meio Ambiente for class 2 freshwater bodies. A significantly higher mean concentration of total phosphorus (p -1 was the result of the uneaten feed and feces of fish. The average concentration of total phosphorus in P3 was lower (0.015 mg L-1, which was assimilated by the aquatic ecosystem. The frequent monitoring of the water parameters is fundamental, so the producer can adjust the management according to environmental conditions, by reducing fish density or changing feeding rates for example, to mitigate or avoid water quality deterioration. 

  5. Effects of sulfite and pH an abscisic acid (ABA) dependent transpiration and on stomatal opening

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, N.; Maruta, I.; Sugahara, K.

    1980-01-01

    In rice, alday, wheat and tobacco (Nicotiana tabacum l. samsun and samsun nn) plants which contained large amounts of ABA, the transpiration rate decreased rapidly with 2 ppM SO/sub 2/ fumigation and reached 20 to 65% of the initial level after 5- to 30-min exposure depending on their ABAj contents. In the cases of broad bean and tobacco (n. Gutinosa l.) with low ABA contents, the rate slightly increased for 20 and 40 min, respectively, after the start of the fumigation and then decreased gradually. The transpiration rates of corn and sorghum, in spite of their extremely low ABA contents, pronouncedly decreased with SO/sub 2/ fumigation and reached 65 and 50%, respectively, of the initial levels after 40-min exposure. Foliar application of 0.04 N HCL to N. tacum l. samsun nn leaves remarkably depressed the transpiration rate, while the application of 0.04 m NA/sub 2/SO/sub 3/ decreased the rate only to the same level as water treatment. Foliar application of either HCL of Na/sub 2/SO/sub 3/ to N. glutinosa l. leaves exerted little change in the transpiration rate. When 10-4 m ABA was applied to broad bean leaves prior to HCl and Na/sub 2/SO/sub 3/ treatment, their transpiration rate was decreased by HCl, but not by Na/sub 2/SO/sub 3/ application. In sonicated epidermal strips peeled from broad bean leaves, Na/sub 2/SO/sub 3/ produced a slight increase in the stomatal aperture size in the absence of ABA, but showed no effect in the presence of ABA. The aperture size was identical in the pH range of 3.0 to 7.0 in the incubation medium. In the presence of ABA in the medium, the aperture size was small in the acidic region of pH with a minimal value at pH 4.0. ABA decreased the aperture size at concentrations above 10-9 m at pH 4.0 and 10-6 m at pH 7.0 in the medium. ABA uptake by epidermal strips was large in the acidic region, especially at pH 4.0.

  6. Effect of a short and severe intermittent drought on transpiration, seed yield components, and harvest index in four landraces of bambara groundnut

    DEFF Research Database (Denmark)

    Jørgensen, Søren Thorndal; Ntundu, W.H.; Ouédraogo, M.

    2011-01-01

    % of pot holding capacity until seed maturity or drought-stressed (DS) in the period from 76 to 85 days after sowing (flowering and early podding stage). During drought, although the total water use differed among the four landraces, transpiration rate and stomatal conductance (gs) responded similarly...... to soil drying. The high soil water thresholds for the reduction of transpiration rate and gs of bambara groundnuts indicate their great sensitivity in the stomatal control over plant water loss during soil drying. Even though the shoot dry weight at maturity was hardly affected by DS, seed yield, seed...... number, and harvest index were all significantly decreased in the DS plants. Among landraces, LunT and Ramayana were more susceptible to DS than S19-3 and Uniswa Red in terms of reduction of seed number and seed yield. The different responses of the landraces to DS may reflect their adaptation...

  7. Enhanced transpiration rate in the high pigment 1 tomato mutant and its physiological significance.

    Science.gov (United States)

    Carvalho, R F; Aidar, S T; Azevedo, R A; Dodd, I C; Peres, L E P

    2011-05-01

    Tomato high pigment (hp) mutants represent an interesting horticultural resource due to their enhanced accumulation of carotenoids, flavonoids and vitamin C. Since hp mutants are known for their exaggerated light responses, the molecules accumulated are likely to be antioxidants, recruited to deal with light and others stresses. Further phenotypes displayed by hp mutations are reduced growth and an apparent disturbance in water loss. Here, we examined the impact of the hp1 mutation and its near isogenic line cv Micro-Tom (MT) on stomatal conductance (gs), transpiration (E), CO(2) assimilation (A) and water use efficiency (WUE). Detached hp1 leaves lost water more rapidly than control leaves, but this behaviour was reversed by exogenous abscisic acid (ABA), indicating the ability of hp1 to respond to this hormone. Although attached hp1 leaves had enhanced gs, E and A compared to control leaves, genotypic differences were lost when water was withheld. Both instantaneous leaf-level WUE and long-term whole plant WUE did not differ between hp1 and MT. Our results indicate a link between exaggerated light response and water loss in hp1, which has important implications for the use of this mutant in both basic and horticultural research. © 2011 German Botanical Society and The Royal Botanical Society of the Netherlands.

  8. Remote sensing of potential and actual daily transpiration of plant canopies based on spectral reflectance and infrared thermal measurements: Concept with preliminary test

    International Nuclear Information System (INIS)

    Inoue, Y.; Moran, M.S.; Pinter, P.J.Jr.

    1994-01-01

    A new concept for estimating potential and actual values of daily transpiration rate of vegetation canopies is presented along with results of an initial test. The method is based on a physical foundation of spectral radiation balance for a vegetation canopy, the key inputs to the model being the remotely sensed spectral reflectance and the surface temperature of the plant canopy. The radiation interception or absorptance is estimated more directly from remotely sensed spectral data than it is from the leaf area index. The potential daily transpiration is defined as a linear function of the absorbed solar radiation, which can be estimated using a linear relationship between the fraction absorptance of solar radiation and the remotely sensed Soil Adjusted Vegetation Index for the canopy. The actual daily transpiration rate is estimated by combining this concept with the Jackson-Idso Crop Water Stress Index, which also can be calculated from remotely sensed plant leaf temperatures measured by infrared thermometry. An initial demonstration with data sets from an alfalfa crop and a rangeland suggests that the method may give reasonable estimates of potential and actual values of daily transpiration rate over diverse vegetation area based on simple remote sensing measurements and basic meteorological parameters

  9. 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

  10. Differential antioxidative responses in transgenic peanut bear no relationship to their superior transpiration efficiency under drought stress.

    Science.gov (United States)

    Bhatnagar-Mathur, Pooja; Devi, M Jyostna; Vadez, Vincent; Sharma, Kiran K

    2009-07-15

    To counter the effects of environmental stresses, the plants must undergo detoxification that is crucial to avoid the accumulation of damaging free oxygen radicals (ROI). Here, we detail the oxidative damage, the antioxidant composition, and the osmoprotection achieved in transgenic plants of peanut overexpressing the AtDREB1A transgene, driven by a stress-inducible promoter (Atrd29A) when exposed to progressive water stress conditions. This study explored the biochemical mechanisms where (i) the antioxidants such as superoxide dismutase (SOD), ascorbate peroxidase (APOX), and glutathione reductase (GR) accumulated in the transgenic plants at comparably higher levels than their untransformed counterparts under dry soil conditions, (ii) a significant increase in the proline levels in the transgenic plants was observed in dry soils, and (iii) a dramatic increase in the lipid peroxidation in the untransformed controls in drier soils. Most of the biochemical parameters related to the antioxidative machinery in the tested peanut transgenics were triggered by the overexpression of AtDREB1A that appeared to differ from the untransformed controls. The antioxidants showed a negative correlation with the fraction of transpirable soil water (FTSW) thresholds, where the normalized transpiration rate (NTR) started decreasing in the tested plants. However, no significant relationship was observed between any of these biochemical indicators and the higher transpiration efficiency (TE) values found in the transgenic events. Our results show that changes in the antioxidative machinery in these transgenic peanut plants (overexpressing the AtDREB1A transcription factor) under water-limiting conditions played no causative role in improved TE.

  11. Effects of Water Stress on Photosynthesis and Chlorophyll Fluorescence of the Sugar Beet

    Directory of Open Access Journals (Sweden)

    HAN Kai-hong

    2015-10-01

    Full Text Available To investigate the effect of water stress and rewatering on sugar beet yield and its corresponding photosynthetic parameters, and to provide the basis of water management for the sugar beet fields, pool experiments in an artificial proof canopy were set up to observe changes of beet net photosynthetic rate(Pn, transpiration rate(Tr, water use efficiency(WUE and stomatal limitation (Ls, intercellular CO2 oncentration(Ci, and PSⅡ maximum quantum yield(Fv/Fm. The results indicated that the diurnal variation of Tr and Pn in CK treatment (whole growth period replenishment at different times near "unimodal" type; and water shortage treatments presented "twin peaks" change. Diurnal transpiration capacity(DTC under water stress at sugar accumulation stage reduced by 70.16%~74.81% and diurnal photosynthetic capacity(DPC was 63.48%~69.96% lower than that of CK, while diurnal water use efficiency(WUEd increased by 19.28%~22.39%. Rehydration helped Tr and Pn recovery, but did not reach unstressed levels. Ls changes under extremely dry environment had a midday trough "twin peaks" feature, and Ci was at "double-dip" in consistent with the timing of Ls; Water stress inhibited and inactivated photochemical reaction center of midday PSⅡ. Water stress led to irreversible decrease in the Pn and Tr, and prolonged the Pn inefficient period, which become the important factor of influencing the sugar beet yield.

  12. 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

  13. Net primary productivity (NPP) and associated parameters for the U.S. outer continental shelf waters, 1998-2009 (NODC Accession 0071184)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This accession consists of monthly net primary productivity (NPP) estimates for 1998-2009 derived from the Vertically Generalized Production Model (VGPM) for the 26...

  14. A new method to determine the water activity and the net isosteric heats of sorption for low moisture foods at elevated temperatures.

    Science.gov (United States)

    Tadapaneni, Ravi Kiran; Yang, Ren; Carter, Brady; Tang, Juming

    2017-12-01

    In recent years, research studies have shown that the thermal resistance of foodborne pathogens in the low moisture foods is greatly influenced by the water activity (a w ) at temperatures relevant to thermal treatments for pathogen control. Yet, there has been a lack of an effective method for accurate measurement of a w at those temperatures. Thus, the main aim of this study was to evaluate a new method for measuring a w of food samples at elevated temperatures. An improved thermal cell with a relative humidity and temperature sensor was used to measure the a w of the three different food samples, namely, organic wheat flour, almond flour, and non-fat milk powder, over the temperature range between 20 and 80°C. For a constant moisture content, the a w data was used to estimate the net isosteric heat of sorption (q st ). The q st values were then used in the Clausius Clapeyron equation (CCE) equation to estimate the moisture sorption isotherm for all test food samples at different temperatures. For all the tested samples of any fixed moisture content, a w value generally increased with the temperature. The energy for sorption decreased with increasing moisture content. With the experimentally determined q st value, CCE describes well about the changes in a w of the food samples between 20 and 80°C. This study presents a method to obtain a w of a food sample for a specific moisture content at different temperatures which could be extended to obtain q st values for different moisture contents and hence, the moisture sorption isotherm of a food sample at different temperatures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Eddy covariance measurements of net C exchange in the CAM bioenergy crop, Agave tequiliana

    Science.gov (United States)

    Owen, Nick A.; Choncubhair, Órlaith Ní; Males, Jamie; del Real Laborde, José Ignacio; Rubio-Cortés, Ramón; Griffiths, Howard; Lanigan, Gary

    2016-04-01

    Bioenergy crop cultivation may focus more on low grade and marginal lands in order to avoid competition with food production for land and water resources. However, in many regions, this would require improvements in plant water-use efficiency that are beyond the physiological capacity of most C3 and C4 bioenergy crop candidates. Crassulacean acid metabolism (CAM) plants, such as Agave tequiliana, can combine high above-ground productivity with as little as 20% of the water demand of C3 and C4 crops. This is achieved through temporal separation of carboxylase activities, with stomata opening at night to allow gas exchange and minimise transpirational losses. Previous studies have employed 'bottom-up' methodologies to investigate carbon (C) accumulation and productivity in Agave, by scaling leaf-level gas exchange and titratable acidity (TA) with leaf area index or maximum productivity. We used the eddy covariance (EC) technique to quantify ecosystem-scale gas exchange over an Agave plantation in Mexico ('top-down' approach). Measurements were made over 252 days, including the transition from wet to dry periods. Results were cross-validated against diel changes in titratable acidity, leaf-unfurling rates, energy exchange fluxes and reported biomass yields. Net ecosystem exchange of CO2 displayed a CAM rhythm that alternated from a net C sink at night to a net C source during the day and partitioned canopy fluxes (gross C assimilation, FA,EC) showed a characteristic four-phase CO2 exchange pattern. The projected ecosystem C balance indicated that the site was a net sink of -333 ± 24 g C m-2 y-1, comprising cumulative soil respiration of 692 ± 7 g C m-2 y-1 and FA,EC of -1025 ± 25 g C m-2 y-1. EC-estimated biomass yield was 20.1 Mg ha-1 y-1. Average integrated daily FA,EC was -234 ± 5 mmol CO2 m-2 d-1 and persisted almost unchanged after 70 days of drought conditions. Our results suggest that the carbon acquisition strategy of drought avoidance employed by Agave

  16. Leaf transpiration efficiency of sweet corn varieties from three eras of breeding

    Science.gov (United States)

    When measured under midday field conditions, modern varieties of corn often have sub-stomatal concentrations of carbon dioxide in excess of those required to saturate photosynthesis. This results in lower leaf transpiration efficiency, the ratio of photosynthesis to transpiration, than potentially ...

  17. Planning of nets

    International Nuclear Information System (INIS)

    Carberry, M

    1996-01-01

    The paper is about the planning of nets in areas of low density like it is the case of the rural areas. The author includes economic and technological aspects, planning of nets, demands and management among others

  18. Annotating Coloured Petri Nets

    DEFF Research Database (Denmark)

    Lindstrøm, Bo; Wells, Lisa Marie

    2002-01-01

    Coloured Petri nets (CP-nets) can be used for several fundamentally different purposes like functional analysis, performance analysis, and visualisation. To be able to use the corresponding tool extensions and libraries it is sometimes necessary to include extra auxiliary information in the CP......-net. An example of such auxiliary information is a counter which is associated with a token to be able to do performance analysis. Modifying colour sets and arc inscriptions in a CP-net to support a specific use may lead to creation of several slightly different CP-nets – only to support the different uses...... of the same basic CP-net. One solution to this problem is that the auxiliary information is not integrated into colour sets and arc inscriptions of a CP-net, but is kept separately. This makes it easy to disable this auxiliary information if a CP-net is to be used for another purpose. This paper proposes...

  19. Transpiration and metabolisation of TCE by willow plants - a pot experiment.

    Science.gov (United States)

    Schöftner, Philipp; Watzinger, Andrea; Holzknecht, Philipp; Wimmer, Bernhard; Reichenauer, Thomas G

    2016-01-01

    Willows were grown in glass cylinders filled with compost above water-saturated quartz sand, to trace the fate of TCE in water and plant biomass. The experiment was repeated once with the same plants in two consecutive years. TCE was added in nominal concentrations of 0, 144, 288, and 721 mg l(-1). Unplanted cylinders were set-up and spiked with nominal concentrations of 721 mg l(-1) TCE in the second year. Additionally, (13)C-enriched TCE solution (δ(13)C = 110.3 ‰) was used. Periodically, TCE content and metabolites were analyzed in water and plant biomass. The presence of TCE-degrading microorganisms was monitored via the measurement of the isotopic ratio of carbon ((13)C/(12)C) in TCE, and the abundance of (13)C-labeled microbial PLFAs (phospholipid fatty acids). More than 98% of TCE was lost via evapotranspiration from the planted pots within one month after adding TCE. Transpiration accounted to 94 to 78% of the total evapotranspiration loss. Almost 1% of TCE was metabolized in the shoots, whereby trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA) were dominant metabolites; less trichloroethanol (TCOH) and TCE accumulated in plant tissues. Microbial degradation was ruled out by δ(13)C measurements of water and PLFAs. TCE had no detected influence on plant stress status as determined by chlorophyll-fluorescence and gas exchange.

  20. Quantitative imaging of water flow in soil and roots using neutron radiography and deuterated water

    Energy Technology Data Exchange (ETDEWEB)

    Zarebanadkouki, Mohsen

    2013-05-08

    Where and how fast do roots take up water? Despite its importance in plant and soil sciences, there is limited experimental information on the location of water uptake along the roots of transpiring plants growing in soil. The answer to this question requires direct and in-situ measurement of the local flow of water into the roots. The aim of this study was to develop and apply a new method to quantify the local fluxes of water into different segments of the roots of intact plants. To this end, neutron radiography was used to trace the transport of deuterated water (D{sub 2}O) into the roots of lupines. Lupines were grown in aluminum containers filled with sandy soil. The soil was partitioned into different compartments using 1 cm-thick layers of coarse sand as capillary barriers. These barriers limited the diffusion of D{sub 2}O within the soil compartments. D{sub 2}O was locally injected into the selected soil compartments during the day (transpiring plants) and night (non-transpiring plants). Transport of D{sub 2}O into roots was then monitored by neutron radiography with spatial resolution of 100 μm and time intervals of 10 seconds. Neutron radiographs showed that: i) transport of D{sub 2}O into roots was faster during the day than during the night; 2) D{sub 2}O quickly moved along the roots towards the shoots during the day, while at night this axial transport was negligible. The differences between day and night measurements were explained by convective transport of D{sub 2}O into the roots. To quantify the net flow of water into roots, a simple convection-diffusion model was developed, where the increase rate of D{sub 2}O concentration in roots depended on the convective transport (net root water uptake) and the diffusion of D{sub 2}O into roots. The results showed that water uptake was not uniform along the roots. Water uptake was higher in the upper soil layers than in the deeper ones. Along an individual roots, the water uptake rate was higher in the

  1. Quantitative imaging of water flow in soil and roots using neutron radiography and deuterated water

    International Nuclear Information System (INIS)

    Zarebanadkouki, Mohsen

    2013-01-01

    Where and how fast do roots take up water? Despite its importance in plant and soil sciences, there is limited experimental information on the location of water uptake along the roots of transpiring plants growing in soil. The answer to this question requires direct and in-situ measurement of the local flow of water into the roots. The aim of this study was to develop and apply a new method to quantify the local fluxes of water into different segments of the roots of intact plants. To this end, neutron radiography was used to trace the transport of deuterated water (D 2 O) into the roots of lupines. Lupines were grown in aluminum containers filled with sandy soil. The soil was partitioned into different compartments using 1 cm-thick layers of coarse sand as capillary barriers. These barriers limited the diffusion of D 2 O within the soil compartments. D 2 O was locally injected into the selected soil compartments during the day (transpiring plants) and night (non-transpiring plants). Transport of D 2 O into roots was then monitored by neutron radiography with spatial resolution of 100 μm and time intervals of 10 seconds. Neutron radiographs showed that: i) transport of D 2 O into roots was faster during the day than during the night; 2) D 2 O quickly moved along the roots towards the shoots during the day, while at night this axial transport was negligible. The differences between day and night measurements were explained by convective transport of D 2 O into the roots. To quantify the net flow of water into roots, a simple convection-diffusion model was developed, where the increase rate of D 2 O concentration in roots depended on the convective transport (net root water uptake) and the diffusion of D 2 O into roots. The results showed that water uptake was not uniform along the roots. Water uptake was higher in the upper soil layers than in the deeper ones. Along an individual roots, the water uptake rate was higher in the proximal segments than in the distal

  2. RadNet Air Data From Sacramento, CA

    Science.gov (United States)

    This page presents radiation air monitoring and air filter analysis data for Sacramento, CA from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  3. RadNet Air Data From Honolulu, HI

    Science.gov (United States)

    This page presents radiation air monitoring and air filter analysis data for Honolulu, HI from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  4. RadNet Air Data From Austin, TX

    Science.gov (United States)

    This page presents radiation air monitoring and air filter analysis data for Austin, TX from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  5. RadNet Air Data From Mason City, IA

    Science.gov (United States)

    This page presents radiation air monitoring and air filter analysis data for Mason City, IA from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  6. RadNet Air Data From Little Rock, AR

    Science.gov (United States)

    This page presents radiation air monitoring and air filter analysis data for Little Rock, AR from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  7. RadNet Air Data From Houston, TX

    Science.gov (United States)

    This page presents radiation air monitoring and air filter analysis data for Houston, TX from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  8. RadNet Air Data From Fort Smith, AR

    Science.gov (United States)

    This page presents radiation air monitoring and air filter analysis data for Fort Smith, AR from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  9. RadNet Air Data From Orlando, FL

    Science.gov (United States)

    This page presents radiation air monitoring and air filter analysis data for Orlando, FL from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  10. THE INTENSITY OF TRANSPIRATION OF THE LEAVES OF GLYCINE MAX (L. MERR. DEPENDING ON THE GROWTH PHASE AND THE TIERED ARRANGEMENT ON THE PLANT

    Directory of Open Access Journals (Sweden)

    A. V. Amelin

    2018-01-01

    Full Text Available The thematic core facilities plan, CCU of Orel state agrarian university "Genetic resources of plants and their use" for a joint program with Shatilovskay of Institute of leguminous and cereal crops, of field and vegetation experiments on the study of specific features of manifestation of the activity of transpiration leaves of soybean are achieved. The object of the study were 10 varieties of soybeans that were grown on plots of 15 m2 in four replications. Seeding was carried out breeding seeder calculated 600 thousand of viable seeds per hectare. the way the plots were allocated systematically with offset. The care of crops was carried out in accordance with the recommended regional events. It was demonstrated that leaf transpiration activity of the culture increases sharply in the transition of plants to the generative period of development, reaching a maximum in the phase of mass fruit formation, when the most active growth and, consequently, the demand for assimilate. The intensity of transpiration of leaves during this period of plant development was by 8.22 mmol H2O/m2c. The highest transpiration activity was typical for the upper leaves located in the generative sphere of plants, the lowest - activity was fount for the lowerst leaves. On the 5th node from the bottom, its value was 2.2 times lower compared to the assimilating leaves at the top of the plants (3-4 knots top. Thus, the most intensive evaporation of the water by leaves are held from 9:00 to 13:00 hours Moscow time. The intensity of transpiration in this period amounted to an average of 5.42 mmol H2O/m2c, which was 19.9% higher than in the morning (from 7:00 to 8:00 and 42.3% in the afternoon (from 15:00 to 17:00.

  11. Water cycle research associated with the CaPE hydrometeorology project (CHymP

    Science.gov (United States)

    Duchon, Claude E.

    1993-01-01

    One outgrowth of the Convection and Precipitation/Electrification (CaPE) experiment that took place in central Florida during July and August 1991 was the creation of the CaPE Hydrometeorology Project (CHymP). The principal goal of this project is to investigate the daily water cycle of the CaPE experimental area by analyzing the numerous land and atmosphere in situ and remotely sensed data sets that were generated during the 40-days of observations. The water cycle comprises the atmospheric branch. In turn, the atmospheric branch comprises precipitation leaving the base of the atmospheric volume under study, evaporation and transpiration entering the base, the net horizontal fluxes of water vapor and cloud water through the volume and the conversion of water vapor to cloud water and vice-versa. The sum of these components results in a time rate of change in the water and liquid water (or ice) content of the atmospheric volume. The components of the land branch are precipitation input to and evaporation and transpiration output from the surface, net horizontal fluxes of surface and subsurface water, the sum of which results in a time rate of change in surface and subsurface water mass. The objective of CHymP is to estimate these components in order to determine the daily water budget for a selected area within the CaPE domain. This work began in earnest in the summer of 1992 and continues. Even estimating all the budget components for one day is a complex and time consuming task. The discussions below provides a short summary of the rainfall quality assessment procedures followed by a plan for estimating the horizontal moisture flux.

  12. Structural and compositional controls on transpiration in 40- and 450-year-old riparian forests in western Oregon, USA.

    Science.gov (United States)

    Moore, Georgianne W; Bond, Barbara J; Jones, Julia A; Phillips, Nathan; Meinzer, Federick C

    2004-05-01

    Large areas of forests in the Pacific Northwest are being transformed to younger forests, yet little is known about the impact this may have on hydrological cycles. Previous work suggests that old trees use less water per unit leaf area or sapwood area than young mature trees of the same species in similar environments. Do old forests, therefore, use less water than young mature forests in similar environments, or are there other structural or compositional components in the forests that compensate for tree-level differences? We investigated the impacts of tree age, species composition and sapwood basal area on stand-level transpiration in adjacent watersheds at the H.J. Andrews Forest in the western Cascades of Oregon, one containing a young, mature (about 40 years since disturbance) conifer forest and the other an old growth (about 450 years since disturbance) forest. Sap flow measurements were used to evaluate the degree to which differences in age and species composition affect water use. Stand sapwood basal area was evaluated based on a vegetation survey for species, basal area and sapwood basal area in the riparian area of two watersheds. A simple scaling exercise derived from estimated differences in water use as a result of differences in age, species composition and stand sapwood area was used to estimate transpiration from late June through October within the entire riparian area of these watersheds. Transpiration was higher in the young stand because of greater sap flux density (sap flow per unit sapwood area) by age class and species, and greater total stand sapwood area. During the measurement period, mean daily sap flux density was 2.30 times higher in young compared with old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees. Sap flux density was 1.41 times higher in young red alder (Alnus rubra Bong.) compared with young P. menziesii trees, and was 1.45 times higher in old P. menziesii compared with old western hemlock (Tsuga heterophylla (Raf

  13. Characterising the water use and hydraulic properties of riparian ...

    African Journals Online (AJOL)

    Daily transpiration was strongly correlated to solar radiation (R2 > 0.81) while the air vapour pressure deficit (VPD) constrained transpiration at high VPD values. We conclude that the water use of the poplar invasions is significantly lower than that of other riparian invasions. The impact of these invasions on the water ...

  14. Increased vapor pressure deficit due to higher temperature leads to greater transpiration and faster mortality during drought for tree seedlings common to the forest-grassland ecotone.

    Science.gov (United States)

    Will, Rodney E; Wilson, Stuart M; Zou, Chris B; Hennessey, Thomas C

    2013-10-01

    Tree species growing along the forest-grassland ecotone are near the moisture limit of their range. Small increases in temperature can increase vapor pressure deficit (VPD) which may increase tree water use and potentially hasten mortality during severe drought. We tested a 40% increase in VPD due to an increase in growing temperature from 30 to 33°C (constant dewpoint 21°C) on seedlings of 10 tree species common to the forest-grassland ecotone in the southern Great Plains, USA. Measurement at 33 vs 30°C during reciprocal leaf gas exchange measurements, that is, measurement of all seedlings at both growing temperatures, increased transpiration for seedlings grown at 30°C by 40% and 20% for seedlings grown at 33°C. Higher initial transpiration of seedlings in the 33°C growing temperature treatment resulted in more negative xylem water potentials and fewer days until transpiration decreased after watering was withheld. The seedlings grown at 33°C died 13% (average 2 d) sooner than seedlings grown at 30°C during terminal drought. If temperature and severity of droughts increase in the future, the forest-grassland ecotone could shift because low seedling survival rate may not sufficiently support forest regeneration and migration. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  15. 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.

  16. A note on India's water budget and evapotranspiration

    Indian Academy of Sciences (India)

    An examination of the budget components indicates that they imply an evapo- transpiration estimate ... India; water budget; evapotranspiration; water policy; water management. J. Earth Syst. Sci. 117 ... L'Environment (2004). California. 0.41.

  17. Evaporation and transpiration from forests in Central Europe - relevance of patch-level studies for spatial scaling

    Science.gov (United States)

    Köstner, B.

    Spatial scaling from patch to the landscape level requires knowledge on the effects of vegetation structure on maximum surface conductances and evaporation rates. The following paper summarizes results on atmospheric, edaphic, and structural controls on forest evaporation and transpiration observed in stands of Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and European beech (Fagus sylvatica). Forest canopy transpiration (Ec) was determined by tree sapflow measurements scaled to the stand level. Estimates of understory transpiration and forest floor evaporation were derived from lysimeter and chamber measurements. Strong reduction of Ec due to soil drought was only observed at a Scots pine stand when soil water content dropped below 16% v/v. Although relative responses of Ec on atmospheric conditions were similar, daily maximum rates of could differ more than 100% between forest patches of different structure (1.5-3.0mmd-1 and 2.6-6.4mmd-1 for spruce and beech, respectively). A significant decrease of Ecmax per leaf area index with increasing stand age was found for monocultures of Norway spruce, whereas no pronounced changes in were observed for beech stands. It is concluded that structural effects on Ecmax can be specified and must be considered for spatial scaling from forest stands to landscapes. Hereby, in conjunction with LAI, age-related structural parameters are important for Norway spruce stands. Although compensating effects of tree canopy layers and understory on total evaporation of forests were observed, more information is needed to quantify structure-function relationships in forests of heterogenous structure.

  18. Transpiration characteristics of forests and shrubland under land cover change within the large caldera of Mt. Aso, Japan

    Science.gov (United States)

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

    2013-12-01

    Grassland within a caldera of Mt. Aso has been maintained for fertilizer production from grasses and cattle feeding. Due to the changes in the agricultural and social structure since 1950's, a large part of the grassland was converted to plantations or abandoned to shrublands. Because vegetations of different plant functional types differ in evapotranspiration; ET, a research project was launched to examine the effects of the ongoing land use change on the ET within the caldera, and consequently affect the surface and groundwater discharge of the region. As the part of the project, transpiration rate; E of the major 3 forest types were investigated using sap flow measurements. Based on the measured data, stomatal conductance; Gs was inversely calculated and its response to the environmental factors was modeled using Jarvis-type equation in order to estimate ET of a given part of the caldera based on the plant functional type and the weather data. The selected forests were conifer plantation, deciduous broadleaved plantation and shrubland, which were installed with sap flow sensors to calculate stand-level transpiration rate. Sap flux; Js did not show clear differences among sites despite the large differences in sapwood area. In early summer solar radiation was limited to low levels due to frequent rainfall events and therefore, Js was the function of solar radiation rather than other environmental factors, such as vapor pressure deficit and soil water content. Gs was well regressed with the vapor pressure deficit and solar radiation. The estimated E based on Gs model and the weather data was 0.3-1.2 mm day-1 for each site and was comparable to the E of grassland in other study sites. Results suggested that transpiration rate in growing was not different between vegetations but its annual value are thought to differ due to the different phenology.

  19. Relationship between transpiration and amino acid accumulation in Brassica leaf discs treated with cytokinins and fusicoccin

    International Nuclear Information System (INIS)

    Kuraishi, Susumu; Ishikawa, Fumio

    1977-01-01

    Both cytokinins and fusicoccin (FC) stimulated the transpiration and the amino acid accumulation in leaf discs of Brassica campestris var. komatsuna. Enhancement effects were of the same magnitude. Both the accumulation and the transpiration were similarly inhibited when vaseline was smeared on the leaf surface. Abscisic acid (ABA) also inhibited those cytokinin-induced effects. The accumulation of amino acid- 14 C was at the cytokinin- or FC-treated site unless the leaf surface was smeared with vaseline. These facts suggest that cytokinin- or FC-induced amino acid accumulation in leaf is caused by the stimulation of transpiration. (auth.)

  20. The sensitivity of stand-scale photosynthesis and transpiration to changes in atmospheric CO2 concentration and climate

    Science.gov (United States)

    Kruijt, B.; Barton, C.; Rey, A.; Jarvis, P. G.

    The 3-dimensional forest model MAESTRO was used to simulate daily and annual photosynthesis and transpiration fluxes of forest stands and the sensitivity of these fluxes to potential changes in atmospheric CO2 concentration ([CO2]), temperature, water stress and phenology. The effects of possible feed-backs from increased leaf area and limitations to leaf nutrition were simulated by imposing changes in leaf area and nitrogen content. Two different tree species were considered: Picea sitchensis (Bong.) Carr., a conifer with long needle longevity and large leaf area, and Betula pendula Roth., a broad-leaved deciduous species with an open canopy and small leaf area. Canopy photosynthetic production in trees was predicted to increase with atmospheric [CO2] and length of the growing season and to decrease with increased water stress. Associated increases in leaf area increased production further only in the B. pendula canopy, where the original leaf area was relatively small. Assumed limitations in N uptake affected B. pendula more than P. sitchensis. The effect of increased temperature was shown to depend on leaf area and nitrogen content. The different sensitivities of the two species were related to their very different canopy structure. Increased [CO2] reduced transpiration, but larger leaf area, early leaf growth, and higher temperature all led to increased water use. These effects were limited by feedbacks from soil water stress. The simulations suggest that, with the projected climate change, there is some increase in stand annual `water use efficiency', but the actual water losses to the atmosphere may not always decrease.

  1. Quantum net dynamics

    International Nuclear Information System (INIS)

    Finkelstein, D.

    1989-01-01

    The quantum net unifies the basic principles of quantum theory and relativity in a quantum spacetime having no ultraviolet infinities, supporting the Dirac equation, and having the usual vacuum as a quantum condensation. A correspondence principle connects nets to Schwinger sources and further unifies the vertical structure of the theory, so that the functions of the many hierarchic levels of quantum field theory (predicate algebra, set theory, topology,hor-ellipsis, quantum dynamics) are served by one in quantum net dynamics

  2. Programming NET Web Services

    CERN Document Server

    Ferrara, Alex

    2007-01-01

    Web services are poised to become a key technology for a wide range of Internet-enabled applications, spanning everything from straight B2B systems to mobile devices and proprietary in-house software. While there are several tools and platforms that can be used for building web services, developers are finding a powerful tool in Microsoft's .NET Framework and Visual Studio .NET. Designed from scratch to support the development of web services, the .NET Framework simplifies the process--programmers find that tasks that took an hour using the SOAP Toolkit take just minutes. Programming .NET

  3. Game Coloured Petri Nets

    DEFF Research Database (Denmark)

    Westergaard, Michael

    2006-01-01

    This paper introduces the notion of game coloured Petri nets. This allows the modeler to explicitly model what parts of the model comprise the modeled system and what parts are the environment of the modeled system. We give the formal definition of game coloured Petri nets, a means of reachability...... analysis of this net class, and an application of game coloured Petri nets to automatically generate easy-to-understand visualizations of the model by exploiting the knowledge that some parts of the model are not interesting from a visualization perspective (i.e. they are part of the environment...

  4. Maintenance of water uptake and reduced water loss contribute to water stress tolerance of Spiraea alba Du Roi and Spiraea tomentosa L.

    Science.gov (United States)

    Stanton, Kelly M; Mickelbart, Michael V

    2014-01-01

    Two primarily eastern US native shrubs, Spiraea alba Du Roi and Spiraea tomentosa L., are typically found growing in wet areas, often with standing water. Both species have potential for use in the landscape, but little is known of their environmental requirements, including their adaptation to water stress. Two geographic accessions of each species were evaluated for their response to water stress under greenhouse conditions. Above-ground biomass, water relations and gas exchange were measured in well-watered and water stress treatments. In both species, water stress resulted in reduced growth, transpiration and pre-dawn water potential. However, both species also exhibited the ability to osmotically adjust to lower soil water content, resulting in maintained midday leaf turgor potential in all accessions. Net CO2 assimilation was reduced only in one accession of S. alba, primarily due to large reductions in stomatal conductance. S. tomentosa lost a larger proportion of leaves than S. alba in response to water stress. The primary water stress tolerance strategies of S. alba and S. tomentosa appear to be the maintenance of water uptake and reduced water loss.

  5. 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).

  6. 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.

  7. Drivers of variability in tree transpiration in a Boreal Black Spruce Forest Chronosequence

    Science.gov (United States)

    Angstmann, J. L.; Ewers, B. E.; Kwon, H.

    2009-12-01

    Boreal forests are of particular interest in climate change studies because of their large land area and ability to sequester and store carbon, which is controlled by water availability. Heterogeneity of these forests is predicted to increase with climate change through the impact of more frequent wildfires, warmer, longer growing seasons, and potential drainage of forested wetlands. This study aims to quantify the influence of stand age, drainage condition, and species on tree transpiration and its drivers in a central Canadian black spruce boreal forest. Heat dissipation sensors were installed in 113 trees (69 Picea mariana (black spruce), 25 Populus tremuloides (trembling aspen), and 19 Pinus banksiana (jack pine) at four stand ages, each containing a well- and poorly-drained site over three growing seasons (2006-2008). Sap flux per unit xylem area, JS, was expressed as transpiration per unit ground area, EC, and transpiration per unit leaf area, EL, using site- and species-specific allometry to obtain sapwood area (AS)and leaf area(AL)per unit ground area. Well-drained, younger Picea mariana daily JS was 47-64% greater than the older well-drained burn ages and younger poorly-drained stands were 64-68% greater than the two oldest poorly-drained stands. Daily EL in the well-drained Picea mariana stands was on average 12-33% higher in younger stand than in the two oldest stands whereas young, poorly-drained Picea mariana had 71% greater daily EL than the older stands. Well-drained Picea mariana trees had 52% higher daily EC than older trees and poorly-drained Picea mariana in the 1964 burn had 42-81% higher daily EC than the oldest stands. Populus tremuloides located in the two youngest stands had daily JS 38-58% greater rates than the 1930 burn, whereas daily EL and EC had no distint differences due to high interannual variability. Pinus banksiana experienced 21-33% greater daily JS in the 1989 burn than in the older 1964 burn for well- and poorly-drained sites

  8. Canopy transpiration of two black locust (Robinia pseudoacacia) plantations with different ages in semi-arid Loess Plateau, China

    Science.gov (United States)

    Jiao, L.

    2015-12-01

    Black locust (Robinia pseudoacacia) was widely planted to control soil erosion and restore degraded ecosystem in Loess Plateau. The water use of the plantations was concerned due to its potential effects on hydrological cycle and regional water resource. Although some studies estimated canopy transpiration (Ec) of the mature black locust plantation, variation in Ec in plantations with different ages was not clear. In this study, we selected two plantations with different ages (12 years and 27 years, denoted as young stand and mature stand, respectively) in similar topographical conditions in Yangjuangou catchment in the central of Loess Plateau. Sap flux density (Fd) and tree biometrics were measured in each stand during the growing season in 2014. Soil water content (SWC) in each plot and meteorological variables in the catchment were simultaneously monitored. Tree transpiration (Et) was derived from Fd and tree sapwood area (As). Canopy transpiration (Ec) was estimated by a product of mean stand sap flux density (Js) and stand total sapwood area (AST). The mean Fd of mature trees was 2-fold larger than that of young trees.However, tree-to-tree variation in Fd among sampled trees within mature stand was evident compared to that within young stand. Mean Et in mature stand was higher than that in young stand. Ec in mature stand was significant higher than that in young stand,with cumulative value of 54 mm and 27 mm respectively. This is attributed to higher Js in mature stand although AST in young is slightly higher than that in mature stand. The patterns of daily Ec during the growing season were similar in both stands during the study period. A exponential saturation model can explain the responses of Ec to vapor deficit pressure (VPD) and solar radiation (Rs) in both stands.The relationship between Ec and SWC was not detected. Our finding suggested that stand age should be taken into consideration when estimated vegetation water use in this region. Further

  9. Aerosol-induced thermal effects increase modelled terrestrial photosynthesis and transpiration

    International Nuclear Information System (INIS)

    Steiner, Allison L.; Chameides, W.L.

    2005-01-01

    Previous studies suggest that the radiative effects of atmospheric aerosols (reducing total radiation while increasing the diffuse fraction) can enhance terrestrial productivity. Here, simulations using a regional climate/terrestrial biosphere model suggest that atmospheric aerosols could also enhance terrestrial photosynthesis and transpiration through an interaction between solar radiation, leaf temperature and stomatal conductance. During midday, clear-sky conditions, sunlit-leaf temperatures can exceed the optimum for photosynthesis, depressing both photosynthesis and transpiration. Aerosols decrease surface solar radiation, thereby reducing leaf temperatures and enhancing sunlit-leaf photosynthesis and transpiration. This modelling study finds that, under certain conditions, this thermal response of aerosols can have a greater impact on photosynthesis and transpiration than the radiative response. This implies that a full understanding of the impact of aerosols on climate and the global carbon cycle requires consideration of the biophysical responses of terrestrial vegetation as well as atmospheric radiative and thermodynamic effects

  10. 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...

  11. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt

    1991-01-01

    This paper describes how Coloured Petri Nets (CP-nets) have been developed — from being a promising theoretical model to being a full-fledged language for the design, specification, simulation, validation and implementation of large software systems (and other systems in which human beings and...

  12. Construction of monophase nets

    International Nuclear Information System (INIS)

    Suarez A, Jose Antonio

    1996-01-01

    The paper refers to the use of monophase loads in commercial residential urbanizations and in small industries, for this reason it is considered unnecessary the construction of three-phase nets. The author makes a historical recount of these nets in Bogota, his capacities, uses and energy savings

  13. 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

  14. Fusion through the NET

    International Nuclear Information System (INIS)

    Spears, B.

    1987-01-01

    The paper concerns the next generation of fusion machines which are intended to demonstrate the technical viability of fusion. In Europe, the device that will follow on from JET is known as NET - the Next European Torus. If the design programme for NET proceeds, Europe could start to build the machine in 1994. The present JET programme hopes to achieve breakeven in the early 1990's. NET hopes to reach ignition in the next century, and so lay the foundation for a demonstration reactor. A description is given of the technical specifications of the components of NET, including: the first wall, the divertors to protect the wall, the array of magnets that provide the fields containing the plasma, the superconducting magnets, and the shield of the machine. NET's research programme is briefly outlined, including the testing programme to optimise conditions in the machine to achieve ignition, and its safety work. (U.K.)

  15. 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.

  16. Transpiration efficiency of a tropical pioneer tree (Ficus insipida) in relation to soil fertility.

    Science.gov (United States)

    Cernusak, Lucas A; Winter, Klaus; Aranda, Jorge; Turner, Benjamin L; Marshall, John D

    2007-01-01

    The response of whole-plant water-use efficiency, termed transpiration efficiency (TE), to variation in soil fertility was assessed in a tropical pioneer tree, Ficus insipida Willd. Measurements of stable isotope ratios (delta(13)C, delta(18)O, delta(15)N), elemental concentrations (C, N, P), plant growth, instantaneous leaf gas exchange, and whole-plant water use were used to analyse the mechanisms controlling TE. Plants were grown individually in 19 l pots with non-limiting soil moisture. Soil fertility was altered by mixing soil with varying proportions of rice husks, and applying a slow release fertilizer. A large variation was observed in leaf photosynthetic rate, mean relative growth rate (RGR), and TE in response to experimental treatments; these traits were well correlated with variation in leaf N concentration. Variation in TE showed a strong dependence on the ratio of intercellular to ambient CO(2) mole fractions (c(i)/c(a)); both for instantaneous measurements of c(i)/c(a) (R(2)=0.69, P <0.0001, n=30), and integrated estimates based on C isotope discrimination (R(2)=0.88, P <0.0001, n=30). On the other hand, variations in the leaf-to-air humidity gradient, unproductive water loss, and respiratory C use probably played only minor roles in modulating TE in the face of variable soil fertility. The pronounced variation in TE resulted from a combination of the strong response of c(i)/c(a) to leaf N, and inherently high values of c(i)/c(a) for this tropical tree species; these two factors conspired to cause a 4-fold variation among treatments in (1-c(i)/c(a)), the term that actually modifies TE. Results suggest that variation in plant N status could have important implications for the coupling between C and water exchange in tropical forest trees.

  17. Effect of nitrogen supply on transpiration and stomatal behaviour of beans (Phaseolus vulgaris L. )

    Energy Technology Data Exchange (ETDEWEB)

    Shimshi, D

    1970-01-01

    The effect of nitrogen supply on the transpiration rate and stomatal opening of potted bean plants was studied in a series of experiments. The transpiration rates of N-supplied plants were higher than those of N-deficient plants when soil moisture was relatively high; as soil moisture approached the wilting range, the transpiration rates of N-supplied plants dropped to below those of N-deficient plants. In spite of the marked differences in transpiration rates, as influenced by soil moisture and nitrogen supply, the stomata appeared closed. By coating the upper or lower surfaces of the leaves with a vapor-impervious compound it was shown that stomatal apertures below the limit of microscopic resolution control the rate of transpiration. Under conditions that encourage stomatal opening (covering the plants with transparent plastic bags), the stomata of the N-deficient plants opened to a lesser degree than those of N-supplied plants. There was some evidence that when stomata were visibly open, transpiration rates were regulated by the degree of plant hydration rather than by the degree of stomatal opening. It is concluded that N-deficient plants fail to open their stomata as widely and to close them as tightly as N-supplied plants. 8 references, 2 tables.

  18. Effect of transpiration on plant accumulation and translocation of PPCP/EDCs

    International Nuclear Information System (INIS)

    Dodgen, Laurel K.; Ueda, Aiko; Wu, Xiaoqin; Parker, David R.; Gan, Jay

    2015-01-01

    The reuse of treated wastewater for agricultural irrigation in arid and hot climates where plant transpiration is high may affect plant accumulation of pharmaceutical and personal care products (PPCPs) and endocrine disrupting chemicals (EDCs). In this study, carrot, lettuce, and tomato plants were grown in solution containing 16 PPCP/EDCs in either a cool-humid or a warm-dry environment. Leaf bioconcentration factors (BCF) were positively correlated with transpiration for chemical groups of different ionized states (p < 0.05). However, root BCFs were correlated with transpiration only for neutral PPCP/EDCs (p < 0.05). Neutral and cationic PPCP/EDCs showed similar accumulation, while anionic PPCP/EDCs had significantly higher accumulation in roots and significantly lower accumulation in leaves (p < 0.05). Results show that plant transpiration may play a significant role in the uptake and translocation of PPCP/EDCs, which may have a pronounced effect in arid and hot climates where irrigation with treated wastewater is common. - Highlights: • Leaf accumulation of PPCP/EDCs is related on plant transpiration. • Cationic and neutral PPCP/EDCs have similar leaf and root accumulation. • Anionic PPCP/EDCs have greater root accumulation and lesser leaf accumulation. • PPCP/EDCs are extensively metabolized in plant tissue and hydroponic solution. - High plant transpiration in arid and hot areas may lead to increased foliar accumulation of PPCP/EDCs from treated wastewater irrigation

  19. Model and calculations for net infiltration

    International Nuclear Information System (INIS)

    Childs, S.W.; Long, A.

    1992-01-01

    In this paper a conceptual model for calculating net infiltration is developed and implemented. It incorporates the following important factors: viability of climate for the next 10,000 years, areal viability of net infiltration, and important soil/plant factors that affect the soil water budget of desert soils. Model results are expressed in terms of occurrence probabilities for time periods. In addition the variability of net infiltration is demonstrated both for change with time and differences among three soil/hydrologic units present at the site modeled

  20. Sensitivity of transpiration to subsurface properties: Exploration with a 1-D model

    Science.gov (United States)

    Vrettas, Michail D.; Fung, Inez Y.

    2017-06-01

    The amount of moisture transpired by vegetation is critically tied to the moisture supply accessible to the root zone. In a Mediterranean climate, integrated evapotranspiration (ET) is typically greater in the dry summer when there is an uninterrupted period of high insolation. We present a 1-D model to explore the subsurface factors that may sustain ET through the dry season. The model includes a stochastic parameterization of hydraulic conductivity, root water uptake efficiency, and hydraulic redistribution by plant roots. Model experiments vary the precipitation, the magnitude and seasonality of ET demand, as well as rooting profiles and rooting depths of the vegetation. The results show that the amount of subsurface moisture remaining at the end of the wet winter is determined by the competition among abundant precipitation input, fast infiltration, and winter ET demand. The weathered bedrock retains ˜30% of the winter rain and provides a substantial moisture reservoir that may sustain ET of deep-rooted (>8 m) trees through the dry season. A small negative feedback exists in the root zone, where the depletion of moisture by ET decreases hydraulic conductivity and enhances the retention of moisture. Hence, hydraulic redistribution by plant roots is impactful in a dry season, or with a less conductive subsurface. Suggestions for implementing the model in the CESM are discussed.

  1. Canopy transpiration for two Japanese cypress forests with contrasting structures

    Science.gov (United States)

    Tsuruta, K.; Komatsu, H.; Kume, T.; Shinohara, Y.; Otsuki, K.

    2012-12-01

    Canopy transpiration (EC) could have large variations among stands with different structures. To evaluate a difference in EC between stands with different structures for Japanese cypress, we observed EC using the sap flow technique in two stands with contrasting structures (age was 19 year and 99 year, mean diameter at breast height was 13.5 cm and 44.6 cm, stem density was 2100 trees ha-1 and 350 trees ha-1, respectively) for 5 months under the same meteorological condition. The mean stand sap flux density (JS) for measurement period and stand sapwood area (AS_stand) for the old stand (0.43 m3 m-2 day-1 and 15.2 m2 ha-1) were lower than those for the young stand (0.62 m3 m-2 day-1 and 20.4 m2 ha-1) by 31.1 % and 25.4 %, respectively. EC is calculated as a product of JS and AS_stand. Therefore the EC in the old stand was lower than that in the young stand by 50 %. We calculated the contribution of the reference JS for a given meteorological conditions (JSref) and the response of JS to the meteorological conditions (JSresp) in the two stands, and examined which is a primary factor for the difference of EC between the two studied stands. The JSresp for the young stand were not considerably different from that for the old stand, whereas JSref for the young stand was greater than that for the old stand. This indicates that JSref (not JSresp) was the primary cause for the difference of EC between the two stands. Further studies observing EC from stands with various structures are needed to generalize our conclusions.

  2. Net Zero Energy Buildings

    DEFF Research Database (Denmark)

    Marszal, Anna Joanna; Bourrelle, Julien S.; Gustavsen, Arild

    2010-01-01

    and identify possible renewable energy supply options which may be considered in calculations. Finally, the gap between the methodology proposed by each organisation and their respective national building code is assessed; providing an overview of the possible changes building codes will need to undergo......The international cooperation project IEA SHC Task 40 / ECBCS Annex 52 “Towards Net Zero Energy Solar Buildings”, attempts to develop a common understanding and to set up the basis for an international definition framework of Net Zero Energy Buildings (Net ZEBs). The understanding of such buildings...

  3. Getting to Net Zero

    Energy Technology Data Exchange (ETDEWEB)

    2016-09-01

    The technology necessary to build net zero energy buildings (NZEBs) is ready and available today, however, building to net zero energy performance levels can be challenging. Energy efficiency measures, onsite energy generation resources, load matching and grid interaction, climatic factors, and local policies vary from location to location and require unique methods of constructing NZEBs. It is recommended that Components start looking into how to construct and operate NZEBs now as there is a learning curve to net zero construction and FY 2020 is just around the corner.

  4. Pro NET Best Practices

    CERN Document Server

    Ritchie, Stephen D

    2011-01-01

    Pro .NET Best Practices is a practical reference to the best practices that you can apply to your .NET projects today. You will learn standards, techniques, and conventions that are sharply focused, realistic and helpful for achieving results, steering clear of unproven, idealistic, and impractical recommendations. Pro .NET Best Practices covers a broad range of practices and principles that development experts agree are the right ways to develop software, which includes continuous integration, automated testing, automated deployment, and code analysis. Whether the solution is from a free and

  5. Transient water stress in a vegetation canopy - Simulations and measurements

    Science.gov (United States)

    Carlson, Toby N.; Belles, James E.; Gillies, Robert R.

    1991-01-01

    Consideration is given to observational and modeling evidence of transient water stress, the effects of the transpiration plateau on the canopy radiometric temperature, and the factors responsible for the onset of the transpiration plateau, such as soil moisture. Attention is also given to the point at which the transient stress can be detected by remote measurement of surface temperature.

  6. 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.

  7. Transpiration efficiency over an annual cycle, leaf gas exchange and wood carbon isotope ratio of three tropical tree species.

    Science.gov (United States)

    Cernusak, Lucas A; Winter, Klaus; Aranda, Jorge; Virgo, Aurelio; Garcia, Milton

    2009-09-01

    Variation in transpiration efficiency (TE) and its relationship with the stable carbon isotope ratio of wood was investigated in the saplings of three tropical tree species. Five individuals each of Platymiscium pinnatum (Jacq.) Dugand, Swietenia macrophylla King and Tectona grandis Linn. f. were grown individually in large (760 l) pots over 16 months in the Republic of Panama. Cumulative transpiration was determined by repeatedly weighing the pots with a pallet truck scale. Dry matter production was determined by destructive harvest. The TE, expressed as experiment-long dry matter production divided by cumulative water use, averaged 4.1, 4.3 and 2.9 g dry matter kg(-1) water for P. pinnatum, S. macrophylla and T. grandis, respectively. The TE of T. grandis was significantly lower than that of the other two species. Instantaneous measurements of the ratio of intercellular to ambient CO(2) partial pressures (c(i)/c(a)), taken near the end of the experiment, explained 66% of variation in TE. Stomatal conductance was lower in S. macrophylla than in T. grandis, whereas P. pinnatum had similar stomatal conductance to T. grandis, but with a higher photosynthetic rate. Thus, c(i)/c(a) and TE appeared to vary in response to both stomatal conductance and photosynthetic capacity. Stem-wood delta(13)C varied over a relatively narrow range of just 2.2 per thousand, but still explained 28% of variation in TE. The results suggest that leaf-level processes largely determined variation among the three tropical tree species in whole-plant water-use efficiency integrated over a full annual cycle.

  8. PhysioNet

    Data.gov (United States)

    U.S. Department of Health & Human Services — The PhysioNet Resource is intended to stimulate current research and new investigations in the study of complex biomedical and physiologic signals. It offers free...

  9. NetSig

    DEFF Research Database (Denmark)

    Horn, Heiko; Lawrence, Michael S; Chouinard, Candace R

    2018-01-01

    Methods that integrate molecular network information and tumor genome data could complement gene-based statistical tests to identify likely new cancer genes; but such approaches are challenging to validate at scale, and their predictive value remains unclear. We developed a robust statistic (Net......Sig) that integrates protein interaction networks with data from 4,742 tumor exomes. NetSig can accurately classify known driver genes in 60% of tested tumor types and predicts 62 new driver candidates. Using a quantitative experimental framework to determine in vivo tumorigenic potential in mice, we found that Net......Sig candidates induce tumors at rates that are comparable to those of known oncogenes and are ten-fold higher than those of random genes. By reanalyzing nine tumor-inducing NetSig candidates in 242 patients with oncogene-negative lung adenocarcinomas, we find that two (AKT2 and TFDP2) are significantly amplified...

  10. Net alkalinity and net acidity 2: Practical considerations

    Science.gov (United States)

    Kirby, C.S.; Cravotta, C.A.

    2005-01-01

    The pH, alkalinity, and acidity of mine drainage and associated waters can be misinterpreted because of the chemical instability of samples and possible misunderstandings of standard analytical method results. Synthetic and field samples of mine drainage having various initial pH values and concentrations of dissolved metals and alkalinity were titrated by several methods, and the results were compared to alkalinity and acidity calculated based on dissolved solutes. The pH, alkalinity, and acidity were compared between fresh, unoxidized and aged, oxidized samples. Data for Pennsylvania coal mine drainage indicates that the pH of fresh samples was predominantly acidic (pH 2.5-4) or near neutral (pH 6-7); ??? 25% of the samples had pH values between 5 and 6. Following oxidation, no samples had pH values between 5 and 6. The Standard Method Alkalinity titration is constrained to yield values >0. Most calculated and measured alkalinities for samples with positive alkalinities were in close agreement. However, for low-pH samples, the calculated alkalinity can be negative due to negative contributions by dissolved metals that may oxidize and hydrolyze. The Standard Method hot peroxide treatment titration for acidity determination (Hot Acidity) accurately indicates the potential for pH to decrease to acidic values after complete degassing of CO2 and oxidation of Fe and Mn, and it indicates either the excess alkalinity or that required for neutralization of the sample. The Hot Acidity directly measures net acidity (= -net alkalinity). Samples that had near-neutral pH after oxidation had negative Hot Acidity; samples that had pH mine drainage treatment can lead to systems with insufficient Alkalinity to neutralize metal and H+ acidity and is not recommended. The use of net alkalinity = -Hot Acidity titration is recommended for the planning of mine drainage treatment. The use of net alkalinity = (Alkalinitymeasured - Aciditycalculated) is recommended with some cautions

  11. Programming NET 35

    CERN Document Server

    Liberty, Jesse

    2009-01-01

    Bestselling author Jesse Liberty and industry expert Alex Horovitz uncover the common threads that unite the .NET 3.5 technologies, so you can benefit from the best practices and architectural patterns baked into the new Microsoft frameworks. The book offers a Grand Tour" of .NET 3.5 that describes how the principal technologies can be used together, with Ajax, to build modern n-tier and service-oriented applications. "

  12. NET SALARY ADJUSTMENT

    CERN Multimedia

    Finance Division

    2001-01-01

    On 15 June 2001 the Council approved the correction of the discrepancy identified in the net salary adjustment implemented on 1st January 2001 by retroactively increasing the scale of basic salaries to achieve the 2.8% average net salary adjustment approved in December 2000. We should like to inform you that the corresponding adjustment will be made to your July salary. Full details of the retroactive adjustments will consequently be shown on your pay slip.

  13. Heat pulse probe measurements of soil water evaporation in a corn field

    Science.gov (United States)

    Latent heat fluxes from cropped fields consist of soil water evaporation and plant transpiration. It is difficult to accurately separate evapotranspiration into evaporation and transpiration. Heat pulse probes have been used to measure bare field subsurface soil water evaporation, however, the appl...

  14. A model exploring whether the coupled effects of plant water supply and demand affect the interpretation of water potentials and irrigation management

    OpenAIRE

    Spinelli, GM; Shackel, KA; Gilbert, ME

    2017-01-01

    © 2017 Elsevier B.V. Water potential is a useful predictive tool in irrigation scheduling as it, or a component, is associated with physiological responses to water deficit. Increasing atmospheric demand for water increases transpiration and decreases water potential for the same stomatal conductance. However, based on supply by the soil-plant-atmosphere-continuum, decreasing soil water potential should decrease stomatal conductance and thus transpiration but also decrease water potential. Su...

  15. 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 controls and their values in production environments. This paper uses transpiration efficiency (biomass produced per unit of water used) as an example of a complex trait of interest to illustrate how the approach can guide modelling, phenotyping, and selection in a breeding program. We believe that this approach, by integrating insights from diverse disciplines, can increase the resource use efficiency of breeding programs for improving yield gains in target populations of environments.

  16. Differential gene expression of wheat progeny with contrasting levels of transpiration efficiency.

    Science.gov (United States)

    Xue, Gang-Ping; McIntyre, C Lynne; Chapman, Scott; Bower, Neil I; Way, Heather; Reverter, Antonio; Clarke, Bryan; Shorter, Ray

    2006-08-01

    High water use efficiency or transpiration efficiency (TE) in wheat is a desirable physiological trait for increasing grain yield under water-limited environments. The identification of genes associated with this trait would facilitate the selection for genotypes with higher TE using molecular markers. We performed an expression profiling (microarray) analysis of approximately 16,000 unique wheat ESTs to identify genes that were differentially expressed between wheat progeny lines with contrasting TE levels from a cross between Quarrion (high TE) and Genaro 81 (low TE). We also conducted a second microarray analysis to identify genes responsive to drought stress in wheat leaves. Ninety-three genes that were differentially expressed between high and low TE progeny lines were identified. One fifth of these genes were markedly responsive to drought stress. Several potential growth-related regulatory genes, which were down-regulated by drought, were expressed at a higher level in the high TE lines than the low TE lines and are potentially associated with a biomass production component of the Quarrion-derived high TE trait. Eighteen of the TE differentially expressed genes were further analysed using quantitative RT-PCR on a separate set of plant samples from those used for microarray analysis. The expression levels of 11 of the 18 genes were positively correlated with the high TE trait, measured as carbon isotope discrimination (Delta(13)C). These data indicate that some of these TE differentially expressed genes are candidates for investigating processes that underlie the high TE trait or for use as expression quantitative trait loci (eQTLs) for TE.

  17. 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.

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

    Science.gov (United States)

    Millan-Almaraz, Jesus Roberto; de Jesus Romero-Troncoso, Rene; Guevara-Gonzalez, Ramon Gerardo; Contreras-Medina, Luis Miguel; Carrillo-Serrano, Roberto Valentin; Osornio-Rios, Roque Alfredo; Duarte-Galvan, Carlos; Rios-Alcaraz, Miguel Angel; Torres-Pacheco, Irineo

    2010-01-01

    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. PMID:22163656

  19. 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.

  20. Numerical simulation of gas-phonon coupling in thermal transpiration flows.

    Science.gov (United States)

    Guo, Xiaohui; Singh, Dhruv; Murthy, Jayathi; Alexeenko, Alina A

    2009-10-01

    Thermal transpiration is a rarefied gas flow driven by a wall temperature gradient and is a promising mechanism for gas pumping without moving parts, known as the Knudsen pump. Obtaining temperature measurements along capillary walls in a Knudsen pump is difficult due to extremely small length scales. Meanwhile, simplified analytical models are not applicable under the practical operating conditions of a thermal transpiration device, where the gas flow is in the transitional rarefied regime. Here, we present a coupled gas-phonon heat transfer and flow model to study a closed thermal transpiration system. Discretized Boltzmann equations are solved for molecular transport in the gas phase and phonon transport in the solid. The wall temperature distribution is the direct result of the interfacial coupling based on mass conservation and energy balance at gas-solid interfaces and is not specified a priori unlike in the previous modeling efforts. Capillary length scales of the order of phonon mean free path result in a smaller temperature gradient along the transpiration channel as compared to that predicted by the continuum solid-phase heat transfer. The effects of governing parameters such as thermal gradients, capillary geometry, gas and phonon Knudsen numbers and, gas-surface interaction parameters on the efficiency of thermal transpiration are investigated in light of the coupled model.

  1. Combining quantitative trait loci analysis with physiological models to predict genotype-specific transpiration rates.

    Science.gov (United States)

    Reuning, Gretchen A; Bauerle, William L; Mullen, Jack L; McKay, John K

    2015-04-01

    Transpiration is controlled by evaporative demand and stomatal conductance (gs ), and there can be substantial genetic variation in gs . A key parameter in empirical models of transpiration is minimum stomatal conductance (g0 ), a trait that can be measured and has a large effect on gs and transpiration. In Arabidopsis thaliana, g0 exhibits both environmental and genetic variation, and quantitative trait loci (QTL) have been mapped. We used this information to create a genetically parameterized empirical model to predict transpiration of genotypes. For the parental lines, this worked well. However, in a recombinant inbred population, the predictions proved less accurate. When based only upon their genotype at a single g0 QTL, genotypes were less distinct than our model predicted. Follow-up experiments indicated that both genotype by environment interaction and a polygenic inheritance complicate the application of genetic effects into physiological models. The use of ecophysiological or 'crop' models for predicting transpiration of novel genetic lines will benefit from incorporating further knowledge of the genetic control and degree of independence of core traits/parameters underlying gs variation. © 2014 John Wiley & Sons Ltd.

  2. Advances in Estimating Current and Future Effects of Climate and Management on Forest Ecosystem Carbon and Water Dynamics at Multiple Scales

    Science.gov (United States)

    Law, B. E.; Still, C. J.; Hudiburg, T. W.; Buotte, P.; Hanson, C. V.

    2017-12-01

    As we examine the integrated effects of climate variability, atmospheric CO2, and land management actions on terrestrial carbon and water processes within regions, and evaluate mitigation and adaptation options, we want our analysis to be as accurate as possible to reduce the risk of negative impacts from management decisions. The use of global land models at regional scales requires modifications for realistic projections. Model evaluation reveals knowledge and data gaps in species sensitivities to climate extremes and responses to land use change and management actions such as restoration. For example, a combination of sapflux and AmeriFlux tower measurements identifies seasonal shifts in the proportion of water vapor exchange that is due to tree transpiration, as well as changes in tree water-use efficiency associated with climate variation. Thermal measurements from an unmanned aerial system quantify canopy temperatures reached during extreme heat events, as well as tree-to-tree thermal variations, which can be related to transpiration dynamics. Diagnosis of land model performance across climate/vegetation gradients includes the combination of atmospheric CO2/CO/H2O observations from aircraft, a tall tower network, and a mobile platform, combined with inverse modeling. This approach identified an ecoregion where the Community Land Model (CLM4.5) underestimated net ecosystem production by 28%, suggesting model challenges in high productivity forests with high soil nitrogen and deep organic soils. We use land-model output of net ecosystem production, harvest and fire emissions to estimate net ecosystem carbon balance, which is input to a Life-Cycle Assessment of wood product use to estimate net carbon emissions to the atmosphere for harvest scenarios and bioenergy production. Such robust and interdisciplinary approaches are needed to more accurately quantify impacts on ecosystems and "what the atmosphere sees" in terms of greenhouse gas sources and impacts on

  3. Wetland tree transpiration modified by river-floodplain connectivity

    Science.gov (United States)

    Allen, Scott T.; Krauss, Ken W.; Cochran, J. Wesley; King, Sammy L.; Keim, Richard F.

    2016-01-01

    Hydrologic connectivity provisions water and nutrient subsidies to floodplain wetlands and may be particularly important in floodplains with seasonal water deficits through its effects on soil moisture. In this study, we measured sapflow in 26 trees of two dominant floodplain forest species (Celtis laevigata and Quercus lyrata) at two hydrologically distinct sites in the lower White River floodplain in Arkansas, USA. Our objective was to investigate how connectivity-driven water table variations affected water use, an indicator of tree function. Meteorological variables (photosynthetically active radiation and vapor pressure deficit) were the dominant controls over water use at both sites; however, water table variations explained some site differences. At the wetter site, highest sapflow rates were during a late-season overbank flooding event, and no flood stress was apparent. At the drier site, sapflow decreased as the water table receded. The late-season flood pulse that resulted in flooding at the wetter site did not affect the water table at the drier site; accordingly, higher water use was not observed at the drier site. The species generally associated with wetter conditions (Q. lyrata) was more positively responsive to the flood pulse. Flood water subsidy lengthened the effective growing season, demonstrating ecological implications of hydrologic connectivity for alleviating water deficits that otherwise reduce function in this humid floodplain wetland.

  4. Spring-summer net community production, new production, particle export and related water column biogeochemical processes in the marginal sea ice zone of the Western Antarctic Peninsula 2012-2014.

    Science.gov (United States)

    Ducklow, Hugh W; Stukel, Michael R; Eveleth, Rachel; Doney, Scott C; Jickells, Tim; Schofield, Oscar; Baker, Alex R; Brindle, John; Chance, Rosie; Cassar, Nicolas

    2018-06-28

    New production (New P, the rate of net primary production (NPP) supported by exogenously supplied limiting nutrients) and net community production (NCP, gross primary production not consumed by community respiration) are closely related but mechanistically distinct processes. They set the carbon balance in the upper ocean and define an upper limit for export from the system. The relationships, relative magnitudes and variability of New P (from 15 NO 3 - uptake), O 2  : argon-based NCP and sinking particle export (based on the 238 U :  234 Th disequilibrium) are increasingly well documented but still not clearly understood. This is especially true in remote regions such as polar marginal ice zones. Here we present a 3-year dataset of simultaneous measurements made at approximately 50 stations along the Western Antarctic Peninsula (WAP) continental shelf in midsummer (January) 2012-2014. Net seasonal-scale changes in water column inventories (0-150 m) of nitrate and iodide were also estimated at the same stations. The average daily rates based on inventory changes exceeded the shorter-term rate measurements. A major uncertainty in the relative magnitude of the inventory estimates is specifying the start of the growing season following sea-ice retreat. New P and NCP(O 2 ) did not differ significantly. New P and NCP(O 2 ) were significantly greater than sinking particle export from thorium-234. We suggest this is a persistent and systematic imbalance and that other processes such as vertical mixing and advection of suspended particles are important export pathways.This article is part of the theme issue 'The marine system of the west Antarctic Peninsula: status and strategy for progress in a region of rapid change'. © 2018 The Author(s).

  5. Biological Petri Nets

    CERN Document Server

    Wingender, E

    2011-01-01

    It was suggested some years ago that Petri nets might be well suited to modeling metabolic networks, overcoming some of the limitations encountered by the use of systems employing ODEs (ordinary differential equations). Much work has been done since then which confirms this and demonstrates the usefulness of this concept for systems biology. Petri net technology is not only intuitively understood by scientists trained in the life sciences, it also has a robust mathematical foundation and provides the required degree of flexibility. As a result it appears to be a very promising approach to mode

  6. Reconfiguration of distribution nets

    International Nuclear Information System (INIS)

    Latorre Bayona, Gerardo; Angarita Marquez, Jorge Luis

    2000-01-01

    Starting of the location of the reconfiguration problem inside the context of the operation of distribution nets, of the quality indicators definition and of the presentation of the alternatives more used for reduction of technical losses, they are related diverse reconfiguration methodologies proposed in the technical literature, pointing out their three principals limitations; also are presents the results of lost obtained starting from simulation works carried out in distribution circuits of the ESSA ESP, which permitting to postulate the reconfiguration of nets like an excellent alternative to reduce technical losses

  7. NET system integration

    International Nuclear Information System (INIS)

    Farfaletti-Casali, F.; Mitchell, N.; Salpietro, E.; Buzzi, U.; Gritzmann, P.

    1985-01-01

    The NET system integration procedure is the process by which the requirements of the various Tokamak machine design areas are brought together to form a compatible machine layout. Each design area produces requirements which generally allow components to be built at minimum cost and operate with minimum technical risk, and the final machine assembly should be achieved with minimum departure from these optimum designs. This is carried out in NET by allowing flexibility in the maintenance and access methods to the machine internal components which must be regularly replaced by remote handling, in segmentation of these internal components and in the number of toroidal field coils

  8. Photochemical Reflectance Index (PRI) as a proxy of Light Use Efficiency (LUE) and transpiration in Mediterranean crop sites

    Science.gov (United States)

    LE Dantec, V.; Chebbi, W.; Boulet, G.; Merlin, O.; Lili-Chabaane, Z.; Er Raki, S.; Ceschia, E.; Khabba, S.; Fanise, P.; Zawilski, B.; Simonneaux, V.; Jarlan, L.

    2016-12-01

    The Photochemical Reflectance Index (PRI) is based on the short term reversible xanthophyll pigment changes accompanying plant stress and therefore of the associated photosynthetic activities. Strong relationships between PRI and Light Use Efficiency (LUE) were shown at leaf and canopy scales and over a wide range of species (Garbulsky et al., 2011). But very few previous works have explored the potential link with plant water status. In this study, we have first analyzed the link between PRI and LUE at canopy scale on two different crops in terms of canopy structure and crop management: olive grove (Tunisia) and wheat grown under different water regimes (irrigated or rainfed) and climate zones (France, Morocco). We have investigated the daily and seasonal dynamics of PRI; linking its variations to meteorological factors (global radiation and sun angle effects, soil water content, relative air humidity …) and plant processes. The highest correlations were mainly observed in clear skies conditions. We have found, whatever site, linear negative relationships between PRI and LUE using data acquired in midday (i.e. in solar zenithal angle condition). Linear link between PRI and sapflow measurements was also revealed. This correlation was obtained over periods characterized by a moderate soil water deficit, i.e. by when transpiration rate was mainly control by Vapor Pressure Deficit. We will then briefly presented alternative and complementary approaches to this index, to detect different level of water stress using thermal infrared emissions.

  9. Stable oxygen isotope analysis reveal vegetation influence on soil water movement and ecosystem water fluxes in a semi-arid oak woodland

    Science.gov (United States)

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

    2015-04-01

    -type probes. It was possible to track soil water redistribution even beyond zero net water flux measured with TDR probes. Under shaded conditions beneath tree crowns, infiltration of precipitation reaches much deeper depths due to the limited radiation energy input and thus, reduced evaporative losses, compared to open areas between crowns. As a consequence, the isotopic enrichment back to initial conditions (as observed before the artificial precipitation event) was strongly delayed. Despite the higher water availability beneath tree crowns, transpiration of understory plants and soil evaporation rates were reduced compared to the open area due to the lack of energy. However, transpiration could be maintained much longer and at higher rates after the precipitation event then soil evaporation. These first results support previous findings at this site where a clear difference in understory plant community structure was observed. Beneath tree crowns, favorable water conditions enables a higher occurrence of grasses and nitrogen fixing forbs, whereas in between tree crowns drought adapted native species became dominant.

  10. Potential for water salvage by removal of non-native woody vegetation from dryland river systems

    Science.gov (United States)

    Doody, T.M.; Nagler, P.L.; Glenn, E.P.; Moore, G.W.; Morino, K.; Hultine, K.R.; Benyon, R.G.

    2011-01-01

    Globally, expansion of non-native woody vegetation across floodplains has raised concern of increased evapotranspiration (ET) water loss with consequent reduced river flows and groundwater supplies. Water salvage programs, established to meet water supply demands by removing introduced species, show little documented evidence of program effectiveness. We use two case studies in the USA and Australia to illustrate factors that contribute to water salvage feasibility for a given ecological setting. In the USA, saltcedar (Tamarix spp.) has become widespread on western rivers, with water salvage programs attempted over a 50-year period. Some studies document riparian transpiration or ET reduction after saltcedar removal, but detectable increases in river base flow are not conclusively shown. Furthermore, measurements of riparian vegetation ET in natural settings show saltcedar ET overlaps the range measured for native riparian species, thereby constraining the possibility of water salvage by replacing saltcedar with native vegetation. In Australia, introduced willows (Salix spp.) have become widespread in riparian systems in the Murray-Darling Basin. Although large-scale removal projects have been undertaken, no attempts have been made to quantify increases in base flows. Recent studies of ET indicate that willows growing in permanently inundated stream beds have high transpiration rates, indicating water savings could be achieved from removal. In contrast, native Eucalyptus trees and willows growing on stream banks show similar ET rates with no net water salvage from replacing willows with native trees. We conclude that water salvage feasibility is highly dependent on the ecohydrological setting in which the non-native trees occur. We provide an overview of conditions favorable to water salvage. Copyright ?? 2011 John Wiley & Sons, Ltd.

  11. [Foliar water use efficiency of Platycladus orientalis sapling under different soil water contents].

    Science.gov (United States)

    Zhang, Yong E; Yu, Xin Xiao; Chen, Li Hua; Jia, Guo Dong; Zhao, Na; Li, Han Zhi; Chang, Xiao Min

    2017-07-18

    The determination of plant foliar water use efficiency will be of great value to improve our understanding about mechanism of plant water consumption and provide important basis of regional forest ecosystem management and maintenance, thus, laboratory controlled experiments were carried out to obtain Platycladus orientalis sapling foliar water use efficiency under five different soil water contents, including instantaneous water use efficiency (WUE gs ) derived from gas exchange and short-term water use efficiency (WUE cp ) caculated using carbon isotope model. The results showed that, controlled by stomatal conductance (g s ), foliar net photosynthesis rate (P n ) and transpiration rate (T r ) increased as soil water content increased, which both reached maximum va-lues at soil water content of 70%-80% field capacity (FC), while WUE gs reached a maximum of 7.26 mmol·m -2 ·s -1 at the lowest soil water content (35%-45% FC). Both δ 13 C of water-soluble leaf and twig phloem material achieved maximum values at the lowest soil water content (35%-45% FC). Besides, δ 13 C values of leaf water-soluble compounds were significantly greater than that of phloem exudates, indicating that there was depletion in 13 C in twig phloem compared with leaf water-soluble compounds and no obvious fractionation in the process of water-soluble material transportation from leaf to twig. Foliar WUE cp also reached a maximum of 7.26 mmol·m -2 ·s -1 at the lowest soil water content (35%-45% FC). There was some difference between foliar WUE gs and WUE cp under the same condition, and the average difference was 0.52 mmol·m -2 ·s -1 . The WUE gs had great space-time variability, by contrast, WUE cp was more representative. It was concluded that P. orientalis sapling adapted to drought condition by increasing water use efficiency and decreasing physiological activity.

  12. 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....

  13. Coloured Petri Nets

    CERN Document Server

    Jensen, Kurt

    2009-01-01

    Coloured Petri Nets (CPN) is a graphical language for modelling and validating concurrent and distributed systems, and other systems in which concurrency plays a major role. This book introduces the constructs of the CPN modelling language and presents the related analysis methods. It provides a comprehensive road map for the practical use of CPN.

  14. Safety nets or straitjackets?

    DEFF Research Database (Denmark)

    Ilsøe, Anna

    2012-01-01

    Does regulation of working hours at national and sector level impose straitjackets, or offer safety nets to employees seeking working time flexibility? This article compares legislation and collective agreements in the metal industries of Denmark, Germany and the USA. The industry has historically...

  15. Neuronal nets in robotics

    International Nuclear Information System (INIS)

    Jimenez Sanchez, Raul

    1999-01-01

    The paper gives a generic idea of the solutions that the neuronal nets contribute to the robotics. The advantages and the inconveniences are exposed that have regarding the conventional techniques. It also describe the more excellent applications as the pursuit of trajectories, the positioning based on images, the force control or of the mobile robots management, among others

  16. Net4Care platform

    DEFF Research Database (Denmark)

    2012-01-01

    , that in turn enables general practitioners and clinical staff to view observations. Use the menus above to explore the site's information resources. To get started, follow the short Hello, World! tutorial. The Net4Care project is funded by The Central Denmark Region and EU via Caretech Innovation....

  17. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt; Kristensen, Lars Michael

    Coloured Petri Nets (CPN) is a graphical language for modelling and validating concurrent and distributed systems, and other systems in which concurrency plays a major role. The development of such systems is particularly challenging because of inherent intricacies like possible nondeterminism an...

  18. Game Theory .net.

    Science.gov (United States)

    Shor, Mikhael

    2003-01-01

    States making game theory relevant and accessible to students is challenging. Describes the primary goal of GameTheory.net is to provide interactive teaching tools. Indicates the site strives to unite educators from economics, political and computer science, and ecology by providing a repository of lecture notes and tests for courses using…

  19. BacillusRegNet

    DEFF Research Database (Denmark)

    Misirli, Goksel; Hallinan, Jennifer; Röttger, Richard

    2014-01-01

    As high-throughput technologies become cheaper and easier to use, raw sequence data and corresponding annotations for many organisms are becoming available. However, sequence data alone is not sufficient to explain the biological behaviour of organisms, which arises largely from complex molecular...... the associated BacillusRegNet website (http://bacillus.ncl.ac.uk)....

  20. Boom Booom Net Radio

    DEFF Research Database (Denmark)

    Grimshaw, Mark Nicholas; Yong, Louisa; Dobie, Ian

    1999-01-01

    of an existing Internet radio station; Boom Booom Net Radio. Whilst necessity dictates some use of technology-related terminology, wherever possible we have endeavoured to keep such jargon to a minimum and to either explain it in the text or to provide further explanation in the appended glossary....

  1. Isotopic estimation of the evapo-transpiration flux in a plain agricultural region (Po plain, Northern Italy)

    International Nuclear Information System (INIS)

    Elmi, Giovanni; Sacchi, Elisa; Zuppi, Gian Maria; Cerasuolo, Marcello; Allais, Enrico

    2013-01-01

    Highlights: ► Isotopic data from 19-months monitoring of water vapour and monthly precipitation. ► The mean annual weighted δ 18 O in rainwater samples is −6.90 ± 2.2. ► Results interpreted in relationship to climatic factors and to air masses circulation. ► Besides local vapour, moisture is carried by continental and maritime circulations. ► A computational method based on isotopes (EMMA) allows quantifying the local vapour fraction. - Abstract: Samples of water vapour and monthly precipitation were collected in Pavia, located 50 km south of Milan (Western Po plain, Northern Italy), over a period of 19 months, from March 2006 to September 2007. Results are interpreted in relation to the local climatic factors (temperature and precipitation rates), and to air mass circulation patterns, derived from sea level pressure maps, geopotential maps and satellite images. Since most water vapour samples represent a mixture of continental air masses and local evapo-transpiration fluxes, a computational method based on the stable isotope content (EMMA) has been used to evaluate the percentage of the different components and to quantify the local vapour fraction. The regression line equation for rainwater samples is: δ 2 H vs.VSMOW =8.8(±0.5)·δ 18 O vs.SMOW +14.5(±3.5)‰(R 2 =0.96;n=17) The slope of the line is extremely high and probably related to the dataset used, which includes two summer seasons and one winter season. In addition, the latter was somewhat anomalous, with recorded average temperatures higher than the average calculated for the years 1970–2002. The mean annual weighted δ 18 O in rainwater samples is equal to −6.90 ± 2.2‰. The regression line equation for water vapour samples is: δ 2 H vs.VSMOW =6.8(±0.3)·δ 18 O vs.SMOW -7.4(±4.9)‰(R 2 =0.92;n=37). The two regression lines meet at δ 18 O = −10.82 ± 13.97‰. This value appears more depleted than the mean annual weighted precipitation value, but is close to the isotope

  2. SUNLIT AND SHADED MAIZE CANOPY WATER LOSS UNDER VARIED WATER STRESS

    Directory of Open Access Journals (Sweden)

    Antonio Odair Santos

    1999-12-01

    Full Text Available ABSTRACT The precise estimation of transpiration from plant canopies is important for the monitoring of crop water use and management of many agricultural operations related to water use planning. The aim of this study was to estimate transpiration from sunlit and shaded fractions of a maize ( Zea mays L. canopy, using the Penman-Monteith energy balance equation with modifications introduced by Fuchs et al. (1987 and Fuchs & Cohen (1989. Estimated values were validated by a heat pulse system, which was used to measure stem sap flow and by a weighing lysimeter. A relationship between incident radiation and leaf stomatal conductance for critical levels of leaf water potential was used to estimate transpiration. Results showed that computed transpiration of the shaded canopy ranged from 27 to 45% of the total transpiration when fluctuations in atmospheric demand and the level of water stress were taken in account. Hourly and daily estimates of transpiration showed agreement with lysimeter and heat pulse measurements on the well-watered plots. For the water-limited plots the precision of the estimate decreased due to difficulties in simulating the canopy stomatal conductance.

  3. Terminal drought-tolerant pearl millet [Pennisetum glaucum (L.) R. Br.] have high leaf ABA and limit transpiration at high vapour pressure deficit.

    Science.gov (United States)

    Kholová, Jana; Hash, C T; Kumar, P Lava; Yadav, Rattan S; Kocová, Marie; Vadez, Vincent

    2010-03-01

    It was previously shown that pearl millet genotypes carrying a terminal drought tolerance quantitative trait locus (QTL) had a lower transpiration rate (Tr; g cm(-2) d(-1)) under well-watered conditions than sensitive lines. Here experiments were carried out to test whether this relates to leaf abscisic acid (ABA) and Tr concentration at high vapour pressure deficit (VPD), and whether that leads to transpiration efficiency (TE) differences. These traits were measured in tolerant/sensitive pearl millet genotypes, including near-isogenic lines introgressed with a terminal drought tolerance QTL (NIL-QTLs). Most genotypic differences were found under well-watered conditions. ABA levels under well-watered conditions were higher in tolerant genotypes, including NIL-QTLs, than in sensitive genotypes, and ABA did not increase under water stress. Well-watered Tr was lower in tolerant than in sensitive genotypes at all VPD levels. Except for one line, Tr slowed down in tolerant lines above a breakpoint at 1.40-1.90 kPa, with the slope decreasing >50%, whereas sensitive lines showed no change in that Tr response across the whole VPD range. It is concluded that two water-saving (avoidance) mechanisms may operate under well-watered conditions in tolerant pearl millet: (i) a low Tr even at low VPD conditions, which may relate to leaf ABA; and (ii) a sensitivity to higher VPD that further restricts Tr, which suggests the involvement of hydraulic signals. Both traits, which did not lead to TE differences, could contribute to absolute water saving seen in part due to dry weight increase differences. This water saved would become critical for grain filling and deserves consideration in the breeding of terminal drought-tolerant lines.

  4. δ2H isotopic flux partitioning of evapotranspiration over a grass field following a water pulse and subsequent dry down

    Science.gov (United States)

    Good, Stephen P.; Soderberg, Keir; Guan, Kaiyu; King, Elizabeth G.; Scanlon, Todd M.; Caylor, Kelly K.

    2014-02-01

    The partitioning of surface vapor flux (FET) into evaporation (FE) and transpiration (FT) is theoretically possible because of distinct differences in end-member stable isotope composition. In this study, we combine high-frequency laser spectroscopy with eddy covariance techniques to critically evaluate isotope flux partitioning of FET over a grass field during a 15 day experiment. Following the application of a 30 mm water pulse, green grass coverage at the study site increased from 0 to 10% of ground surface area after 6 days and then began to senesce. Using isotope flux partitioning, transpiration increased as a fraction of total vapor flux from 0% to 40% during the green-up phase, after which this ratio decreased while exhibiting hysteresis with respect to green grass coverage. Daily daytime leaf-level gas exchange measurements compare well with daily isotope flux partitioning averages (RMSE = 0.0018 g m-2 s-1). Overall the average ratio of FT to FET was 29%, where uncertainties in Keeling plot intercepts and transpiration composition resulted in an average of uncertainty of ˜5% in our isotopic partitioning of FET. Flux-variance similarity partitioning was partially consistent with the isotope-based approach, with divergence occurring after rainfall and when the grass was stressed. Over the average diurnal cycle, local meteorological conditions, particularly net radiation and relative humidity, are shown to control partitioning. At longer time scales, green leaf area and available soil water control FT/FET. Finally, we demonstrate the feasibility of combining isotope flux partitioning and flux-variance similarity theory to estimate water use efficiency at the landscape scale.

  5. Water-deficit tolerant classification in mutant lines of indica rice

    Directory of Open Access Journals (Sweden)

    Suriyan Cha-um

    2012-04-01

    Full Text Available Water shortage is a major abiotic stress for crop production worldwide, limiting the productivity of crop species, especially in dry-land agricultural areas. This investigation aimed to classify the water-deficit tolerance in mutant rice (Oryza sativa L. spp. indica genotypes during the reproductive stage. Proline content in the flag leaf of mutant lines increased when plants were subjected to water deficit. Relative water content (RWC in the flag leaf of different mutant lines dropped in relation to water deficit stress. A decrease RWC was positively related to chlorophyll a degradation. Chlorophyll a , chlorophyll b , total chlorophyll , total carotenoids , maximum quantum yield of PSII , stomatal conductance , transpiration rate and water use efficiency in mutant lines grown under water deficit conditions declined in comparison to the well-watered, leading to a reduction in net-photosynthetic rate. In addition, when exposed to water deficit, panicle traits, including panicle length and fertile grains were dropped. The biochemical and physiological data were subjected to classify the water deficit tolerance. NSG19 (positive control and DD14 were identified as water deficit tolerant, and AA11, AA12, AA16, BB13, BB16, CC12, CC15, EE12, FF15, FF17, G11 and IR20 (negative control as water deficit sensitive, using Ward's method.

  6. Transpirational drying and costs for transporting woody biomass - a preliminary review

    Science.gov (United States)

    Bryce J. Stokes; Bryce J. McDonaStokes; Timothy P. McDonald; Tyrone Kelley

    1993-01-01

    High transport costs arc a factor to consider in the use of forest residues for fuel. Costs can be reduced by increasing haul capacities, reducing high moisture contents, and improving trucking efficiency. The literature for transpirational drying and the economics of hauling woody biomass is summarized here. Some additional, unpublished roundwood and chipdrying test...

  7. 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...

  8. Effect of Transpiration on Plant Accumulation and Translocation of PPCP/EDCs

    Science.gov (United States)

    Dodgen, Laurel K; Ueda, Aiko; Wu, Xiaoqin; Parker, David R; Gan, Jay

    2015-01-01

    The reuse of treated wastewater for agricultural irrigation in arid and hot climates where plant transpiration is high may affect plant accumulation of pharmaceutical and personal care products (PPCPs) and endocrine disrupting chemicals (EDCs). In this study, carrot, lettuce, and tomato plants were grown in solution containing 16 PPCP/EDCs in either a cool-humid or a warm-dry environment. Leaf bioconcentration factors (BCF) were positively correlated with transpiration for chemical groups of different ionized states (p < 0.05). However, root BCFs were correlated with transpiration only for neutral PPCP/EDCs (p < 0.05). Neutral and cationic PPCP/EDCs showed similar accumulation, while anionic PPCP/EDCs had significantly higher accumulation in roots and significantly lower accumulation in leaves (p < 0.05). Results show that plant transpiration may play a significant role in the uptake and translocation of PPCP/EDCs, which may have a pronounced effect in arid and hot climates where irrigation with treated wastewater is common. PMID:25594843

  9. Relationships between stem diameter, sapwood area, leaf area and transpiration in a young mountain ash forest.

    Science.gov (United States)

    Vertessy, R A; Benyon, R G; O'Sullivan, S K; Gribben, P R

    1995-09-01

    We examined relationships between stem diameter, sapwood area, leaf area and transpiration in a 15-year-old mountain ash (Eucalyptus regnans F. Muell.) forest containing silver wattle (Acacia dealbata Link.) as a suppressed overstory species and mountain hickory (Acacia frigescens J.H. Willis) as an understory species. Stem diameter explained 93% of the variation in leaf area, 96% of the variation in sapwood area and 88% of the variation in mean daily spring transpiration in 19 mountain ash trees. In seven silver wattle trees, stem diameter explained 87% of the variation in sapwood area but was a poor predictor of the other variables. When transpiration measurements from individual trees were scaled up to a plot basis, using stem diameter values for 164 mountain ash trees and 124 silver wattle trees, mean daily spring transpiration rates of the two species were 2.3 and 0.6 mm day(-1), respectively. The leaf area index of the plot was estimated directly by destructive sampling, and indirectly with an LAI-2000 plant canopy analyzer and by hemispherical canopy photography. All three methods gave similar results.

  10. 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...

  11. Leaf transpiration efficiency in corn varieties grown at elevated carbon dioxide

    Science.gov (United States)

    Higher leaf transpiration efficiency (TE) without lower photosynthesis has been identified in some varieties of corn in field tests, and could be a useful trait to improve yield under dry conditions without sacrificing yield under favorable conditions. However, because the carbon dioxide concentrat...

  12. Effect of solar loading on greenhouse containers used in transpiration efficiency screening

    Science.gov (United States)

    Earlier we described a simple high throughput method of screening sorghum for transpiration efficiency (TE). Subsequently it was observed that while results were consistent between lines exhibiting high and low TE, ranking between lines with similar TE was variable. We hypothesized that variable mic...

  13. Water use and carbon exchange of red oak- and eastern hemlock-dominated forests in the northeastern USA : implications for ecosystem-level effects of hemlock woolly adelgid

    International Nuclear Information System (INIS)

    Hadley, J.L.; Kuzeja, P.S.; Singh, S.

    2008-01-01

    This study used the eddy flux method to measure water use and carbon exchange of a red oak forest and an eastern hemlock-dominated forest located in north-central Massachusetts over a period of 2 years. The study demonstrated that water use by the red oak reached approximately 4 mm per day -1 . A maximum rate of 2 mm per day -1 was used by the eastern hemlock forest. Carbon (C) uptake rates were higher in the red oak forest than in the eastern hemlock forest. Measurements of sap flux suggested that transpiration of red oak and black birches in the eastern hemlock forest were approximately twice as high as transpiration rates observed for eastern hemlock. However, annual C storage of eastern hemlock was almost equal to C storage rates of the red oak forest, due to net C uptake by the hemlock during an unusually warm fall and spring. The study showed that C storage by eastern hemlock forests will increase as a result of climatic warming. Although forest water use will decrease as a result of eastern hemlock due to insect disturbances, the replacement of eastern hemlock by deciduous species such as red oak will increase water use during the summer-time in areas where hemlock is a predominant species. 24 refs., 5 tabs., 11 figs

  14. SolNet

    DEFF Research Database (Denmark)

    Jordan, Ulrike; Vajen, Klaus; Bales, Chris

    2014-01-01

    -accompanying Master courses, placements of internships, and PhD scholarship projects. A new scholarship project, “SHINE”, was launched in autumn 2013 in the frame work of the Marie Curie program of the European Union (Initial Training Network, ITN). 13 PhD-scholarships on solar district heating, solar heat......SolNet, founded in 2006, is the first coordinated International PhD education program on Solar Thermal Engineering. The SolNet network is coordinated by the Institute of Thermal Engineering at Kassel University, Germany. The network offers PhD courses on solar heating and cooling, conference...... for industrial processes, as well as sorption stores and materials started in December 2013. Additionally, the project comprises a training program with five PhD courses and several workshops on solar thermal engineering that will be open also for other PhD students working in the field. The research projects...

  15. The functional dependence of canopy conductance on water vapor pressure deficit revisited

    NARCIS (Netherlands)

    Fuchs, Marcel; Stanghellini, Cecilia

    2018-01-01

    Current research seeking to relate between ambient water vapor deficit (D) and foliage conductance (gF) derives a canopy conductance (gW) from measured transpiration by inverting the coupled transpiration model to yield gW = m − n ln(D) where m and n are fitting parameters. In contrast, this paper

  16. Turkey's net energy consumption

    International Nuclear Information System (INIS)

    Soezen, Adnan; Arcaklioglu, Erol; Oezkaymak, Mehmet

    2005-01-01

    The main goal of this study is to develop the equations for forecasting net energy consumption (NEC) using an artificial neural-network (ANN) technique in order to determine the future level of energy consumption in Turkey. In this study, two different models were used in order to train the neural network. In one of them, population, gross generation, installed capacity and years are used in the input layer of the network (Model 1). Other energy sources are used in input layer of network (Model 2). The net energy consumption is in the output layer for two models. Data from 1975 to 2003 are used for the training. Three years (1981, 1994 and 2003) are used only as test data to confirm this method. The statistical coefficients of multiple determinations (R 2 -value) for training data are equal to 0.99944 and 0.99913 for Models 1 and 2, respectively. Similarly, R 2 values for testing data are equal to 0.997386 and 0.999558 for Models 1 and 2, respectively. According to the results, the net energy consumption using the ANN technique has been predicted with acceptable accuracy. Apart from reducing the whole time required, with the ANN approach, it is possible to find solutions that make energy applications more viable and thus more attractive to potential users. It is also expected that this study will be helpful in developing highly applicable energy policies

  17. 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

  18. Numerical investigation on critical heat flux and coolant volume required for transpiration cooling with phase change

    International Nuclear Information System (INIS)

    He, Fei; Wang, Jianhua

    2014-01-01

    Highlights: • Five states during the transpiration cooling are discussed. • A suit of applicable program is developed. • The variations of the thickness of two-phase region and the pressure are analyzed. • The relationship between heat flux and coolant mass flow rate is presented. • An approach is given to define the desired case of transpiration cooling. - Abstract: The mechanism of transpiration cooling with liquid phase change is numerically investigated to protect the thermal structure exposed to extremely high heat flux. According to the results of theoretical analysis, there is a lower critical and an upper critical external heat flux corresponding a certain coolant mass flow rate, between the two critical values, the phase change of liquid coolant occurs within porous structure. A strongly applicable self-edit program is developed to solve the states of fluid flow and heat transfer probably occurring during the phase change procedure. The distributions of temperature and saturation in these states are presented. The variations of the thickness of two-phase region and the pressure including capillary are analyzed, and capillary pressure is found to be the main factor causing pressure change. From the relationships between the external heat flux and coolant mass flow rate obtained at different cooling cases, an approach is given to estimate the maximal heat flux afforded and the minimal coolant consumption required by the desired case of transpiration cooling. Thus the pressure and coolant consumption required in a certain thermal circumstance can be determined, which are important in the practical application of transpiration cooling

  19. Why size matters: the interactive influences of tree diameter distribution and sap flow parameters on upscaled transpiration.

    Science.gov (United States)

    Berry, Z Carter; Looker, Nathaniel; Holwerda, Friso; Gómez Aguilar, León Rodrigo; Ortiz Colin, Perla; González Martínez, Teresa; Asbjornsen, Heidi

    2018-02-01

    In stands with a broad range of diameters, a small number of very large trees can disproportionately influence stand basal area and transpiration (Et). Sap flow-based Et estimates may be particularly sensitive to large trees due to nonlinear relationships between tree-level water use (Q) and tree diameter at breast height (DBH). Because Q is typically predicted on the basis of DBH and sap flow rates measured in a subset of trees and then summed to obtain Et, we assessed the relative importance of DBH and sap flow variables (sap velocity, Vs, and sapwood depth, Rs) in determining the magnitude of Et and its dependence on large trees in a tropical montane forest ecosystem. Specifically, we developed a data-driven simulation framework to vary the relationship between DBH and Vs and stand DBH distribution and then calculate Q, Et and the proportion of Et contributed by the largest tree in each stand. Our results demonstrate that variation in how Rs is determined in the largest trees can alter estimates up to 26% of Et while variation in how Vs is determined can vary results by up to 132%. Taken together, these results highlight a great need to expand our understanding of water transport in large trees as this hinders our ability to predict water fluxes accurately from stand to catchment scales. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. Drought effect on growth, gas exchange and yield, in two strains of local barley Ardhaoui, under water deficit conditions in southern Tunisia.

    Science.gov (United States)

    Thameur, Afwa; Lachiheb, Belgacem; Ferchichi, Ali

    2012-12-30

    Two local barley strains cv. Ardhaoui originated from Tlalit and Switir, sourthern Tunisia were grown in pots in a glasshouse assay, under well-watered conditions for a month. Plants were then either subjected to water deficit (treatment) or continually well-watered (control). Control pots were irrigated several times each week to maintain soil moisture near field capacity (FC), while stress pots experienced soil drying by withholding irrigation until they reached 50% of FC. Variation in relative water content, leaf area, leaf appearance rate and leaf gas exchange (i.e. net CO(2) assimilation rate (A), transpiration (E), and stomatal conductance (gs)) in response to water deficit was investigated. High leaf relative water content (RWC) was maintained in Tlalit by stomatal closure and a reduction of leaf area. Reduction in leaf area was due to decline in leaf gas exchange during water deficit. Tlalit was found to be drought tolerant and able to maintain higher leaf RWC under drought conditions. Water deficit treatment reduced stomatal conductance by 43% at anthesis. High net CO(2) assimilation rate under water deficit was associated with high RWC (r = 0.998; P gas exchange parameters were found, which can give some indications on the degree of drought tolerance. Thus, the ability of the low leaf area plants to maintain higher RWC could explain the differences in drought tolerance in studied barley strains. Results showed that Tlalit showed to be more efficient and more productive than Switir. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. From evaporating pans to transpiring plants (John Dalton Medal Lecture)

    Science.gov (United States)

    Roderick, Michael

    2013-04-01

    The name of the original inventor of irrigated agriculture is lost to antiquity. Nevertheless, one can perhaps imagine an inquisitive desert inhabitant noting the greener vegetation along a watercourse and putting two and two together. Once water was being supplied and food was being produced it would be natural to ask a further question: how much water can we put on? No doubt much experience was gained down through the ages, but again, one can readily imagine someone inverting a rain gauge, filling it with water and measuring how fast the water evaporated. The inverted rain gauge measures the demand for water by the atmosphere. We call it the evaporative demand. I do not know if this is what actually happened but it sure makes an interesting start to a talk. Evaporation pans are basically inverted rain gauges. The rain gauge and evaporation pan measure the supply and demand respectively and these instruments are the workhorses of agricultural meteorology. Rain gauges are well known. Evaporation pans are lesser known but are in widespread use and are a key part of several national standardized meteorological networks. Many more pans are used for things like scheduling irrigation on farms or estimating evaporation from lakes. Analysis of the long records now available from standardized networks has revealed an interesting phenomenon, i.e., pan evaporation has increased in some places and decreased in other but when averaged over large numbers of pans there has been a steady decline. These independent reports from, for example, the US, Russia, China, India, Thailand, are replicated in the southern hemisphere in, for example, Australia, New Zealand and South Africa. One often hears the statement that because the earth is expected to warm with increasing greenhouse gas emissions then it follows that water will evaporate faster. The pan evaporation observations show that this widely held expectation is wrong. When expectations disagree with observations, it is the

  2. [Effects of soil water status on gas exchange of peanut and early rice leaves].

    Science.gov (United States)

    Chen, Jiazhou; Lü, Guoan; He, Yuanqiu

    2005-01-01

    The gas exchange characteristics of peanut and early rice leaves were investigated in experimental plots under different soil water conditions over a long growth period. The results showed that at the branching stage of peanut, the stomatal conductance (Gs) and transpiration rate (Tr) decreased slightly under mild and moderate soil water stress, while the net photosynthetic rate (Pn) and leaf water use efficiency (WUE) increased. The Gs/Tr ratio also increased under mild water stress, but decreased under moderate water stress. At podding stage, the Gs, Tr, Gs/Tr ratio and Pn decreased, while WUE increased significantly under mild and moderate water stress. The peanut was suffered from water stress at its pod setting stage. At the grain filling stage of early rice, the Gs, Tr and Gs/Tr ratio fluctuated insignificantly under mild and moderate water stress, while Pn and WUE increased significantly, with an increase in grain yield under mild water stress. It's suggested that the combination of Gs and Gs/Tr ratio could be a reference index for crop water stress, namely, crops could be hazarded by water stress when Gs and Gs/Tr decreased synchronously.

  3. Effects of soil water and nitrogen availability on photosynthesis and water use efficiency of Robinia pseudoacacia seedlings.

    Science.gov (United States)

    Liu, Xiping; Fan, Yangyang; Long, Junxia; Wei, Ruifeng; Kjelgren, Roger; Gong, Chunmei; Zhao, Jun

    2013-03-01

    The efficient use of water and nitrogen (N) to promote growth and increase yield of fruit trees and crops is well studied. However, little is known about their effects on woody plants growing in arid and semiarid areas with limited water and N availability. To examine the effects of water and N supply on early growth and water use efficiency (WUE) of trees on dry soils, one-year-old seedlings of Robinia pseudoacacia were exposed to three soil water contents (non-limiting, medium drought, and severe drought) as well as to low and high N levels, for four months. Photosynthetic parameters, leaf instantaneous WUE (WUEi) and whole tree WUE (WUEb) were determined. Results showed that, independent of N levels, increasing soil water content enhanced the tree transpiration rate (Tr), stomatal conductance (Gs), intercellular CO2 concentration (Ci), maximum net assimilation rate (Amax), apparent quantum yield (AQY), the range of photosynthetically active radiation (PAR) due to both reduced light compensation point and enhanced light saturation point, and dark respiration rate (Rd), resulting in a higher net photosynthetic rate (Pn) and a significantly increased whole tree biomass. Consequently, WUEi and WUEb were reduced at low N, whereas WUEi was enhanced at high N levels. Irrespective of soil water availability, N supply enhanced Pn in association with an increase of Gs and Ci and a decrease of the stomatal limitation value (Ls), while Tr remained unchanged. Biomass and WUEi increased under non-limiting water conditions and medium drought, as well as WUEb under all water conditions; but under severe drought, WUEi and biomass were not affected by N application. In conclusion, increasing soil water availability improves photosynthetic capacity and biomass accumulation under low and high N levels, but its effects on WUE vary with soil N levels. N supply increased Pn and WUE, but under severe drought, N supply did not enhance WUEi and biomass.

  4. Less transpiration and good quality thanks to NIR-screen

    NARCIS (Netherlands)

    Stanghellini, C.; Kempkes, F.L.K.; Hemming, S.; Jianfeng, D.

    2009-01-01

    Materials or additives for greenhouse cover that reflect or absorb a part of the NIR radiation can decrease the cooling requirement for the greenhouse and increase water use efficiency of the crop. By reducing the ventilation requirement, it might even decrease emissions of carbon dioxide from

  5. Net one, net two: the primary care network income statement.

    Science.gov (United States)

    Halley, M D; Little, A W

    1999-10-01

    Although hospital-owned primary care practices have been unprofitable for most hospitals, some hospitals are achieving competitive advantage and sustainable practice operations. A key to the success of some has been a net income reporting tool that separates practice operating expenses from the costs of creating and operating a network of practices to help healthcare organization managers, physicians, and staff to identify opportunities to improve the network's financial performance. This "Net One, Net Two" reporting allows operations leadership to be held accountable for Net One expenses and strategic leadership to be held accountable for Net Two expenses.

  6. Proof Nets for Lambek Calculus

    NARCIS (Netherlands)

    Roorda, Dirk

    1992-01-01

    The proof nets of linear logic are adapted to the non-commutative Lambek calculus. A different criterion for soundness of proof nets is given, which gives rise to new algorithms for proof search. The order sensitiveness of the Lambek calculus is reflected by the planarity condition on proof nets;

  7. Net metering: zero electricity bill

    International Nuclear Information System (INIS)

    Mangi, A.; Khan, Z.

    2011-01-01

    Worldwide move towards renewable energy sources, environmental concerns and decentralization of the power sector have made net metering an attractive option for power generation at small scale. This paper discusses the net metering, economical issues of renewable sources in Pakistan, technical aspects, installation suitability according to varying terrain, existing utility rules and formulation of legislation for net metering making it economically attractive. (author)

  8. The Net Advance of Physics

    Science.gov (United States)

    THE NET ADVANCE OF PHYSICS Review Articles and Tutorials in an Encyclopædic Format Established 1995 [Link to MIT] Computer support for The Net Advance of Physics is furnished by The Massachusetts Newest Additions SPECIAL FEATURES: Net Advance RETRO: Nineteenth Century Physics History of Science

  9. Assimilation and water relations of dryland castor at different intensities of solar radiation

    International Nuclear Information System (INIS)

    Balasubramanian, V.; Venkateswarlu, S.

    1995-01-01

    Primary racemes of dryland castor develop during later part of rainy season and secondaries and tertiaries develop during post-rainy season. The reproductive phase is therefore subjected to variation in soil moisture availability and solar radiation intensity. The objective of the study was to find out the influence of fluctuation in solar radiation intensity on photosynthetic rate, transpiration rate, transpiration efficiency, stomatal conductance and leaf water potential during early and late reproductive phase of castor. When photosynthetically active radiation was less than 1000 mu-mol m-2s-1, transpiration efficiency decreased because reduction in photosynthesis rate was more than that in transpiration rate. Transpiration efficiency also decreased, when radiation was above 1500 mu-mol m-2s-1 because of increase only in transpiration rate. Leaf water potential was higher during early than during late reproductive phase at similar radiation intensity. Transpiration rate was lower and transpiration efficiency was more during early phase when radiation was above 1500 mu-mol m-2s-1. Photosynthetically active radiation and leaf water potential were inversely related

  10. Separating active and passive influences on stomatal control of transpiration.

    Science.gov (United States)

    McAdam, Scott A M; Brodribb, Timothy J

    2014-04-01

    Motivated by studies suggesting that the stomata of ferns and lycophytes do not conform to the standard active abscisic acid (ABA) -mediated stomatal control model, we examined stomatal behavior in a conifer species (Metasequoia glyptostroboides) that is phylogenetically midway between the fern and angiosperm clades. Similar to ferns, daytime stomatal closure in response to moderate water stress seemed to be a passive hydraulic process in M. glyptostroboides immediately alleviated by rehydrating excised shoots. Only after prolonged exposure to more extreme water stress did active ABA-mediated stomatal closure become important, because foliar ABA production was triggered after leaf turgor loss. The influence of foliar ABA on stomatal conductance and stomatal aperture was highly predictable and additive with the passive hydraulic influence. M. glyptostroboides thus occupies a stomatal behavior type intermediate between the passively controlled ferns and the characteristic ABA-dependent stomatal closure described in angiosperm herbs. These results highlight the importance of considering phylogeny as a major determinant of stomatal behavior.

  11. Master Robotic Net

    Directory of Open Access Journals (Sweden)

    Vladimir Lipunov

    2010-01-01

    Full Text Available The main goal of the MASTER-Net project is to produce a unique fast sky survey with all sky observed over a single night down to a limiting magnitude of 19-20. Such a survey will make it possible to address a number of fundamental problems: search for dark energy via the discovery and photometry of supernovae (including SNIa, search for exoplanets, microlensing effects, discovery of minor bodies in the Solar System, and space-junk monitoring. All MASTER telescopes can be guided by alerts, and we plan to observe prompt optical emission from gamma-ray bursts synchronously in several filters and in several polarization planes.

  12. Water use characteristics of black mangrove (Avicennia germinans) communities along an ecotone with marsh at a northern geographical limit

    Science.gov (United States)

    Krauss, Ken W.; McKee, Karen L.; Hester, Mark W.

    2014-01-01

    Mangroves are expanding into warm temperate-zone salt marsh communities in several locations globally. Although scientists have discovered that expansion might have modest effects on ecosystem functioning, water use characteristics have not been assessed relative to this transition. We measured early growing season sapflow (Js) and leaf transpiration (Tr) in Avicennia germinans at a latitudinal limit along the northern Gulf of Mexico (Louisiana, United States) under both flooded and drained states and used these data to scale vegetation water use responses in comparison with Spartina alterniflora. We discovered strong convergence when using either Js or Tr for determining individual tree water use, indicating tight connection between transpiration and xylem water movement in small Avicennia trees. When Tr data were combined with leaf area indices for the region with the use of three separate approaches, we determined that Avicennia stands use approximately 1·0–1·3 mm d–1 less water than Spartina marsh. Differences were only significant with the use of two of the three approaches, but are suggestive of net conservation of water as Avicennia expands into Spartina marshes at this location. Average Js for Avicennia trees was not influenced by flooding, but maximum Js was greater when sites were flooded. Avicennia and Spartina closest to open water (shoreline) used more water than interior locations of the same assemblages by an average of 1·3 mm d−1. Lower water use by Avicennia may indicate a greater overall resilience to drought relative to Spartina, such that aperiodic drought may interact with warmer winter temperatures to facilitate expansion of Avicennia in some years.

  13. 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

    The Haouz region, typical of southern Mediterranean basins, is characterized by a semi-arid climate, with average annual rainfall of 250, whilst evaporative demand is about 1600 mm per year. Under these conditions, crop irrigation is inevitable for growth and development. Irrigated agriculture currently consumes the majority of total available water (up to 85%), making it critical for more efficient water use. Flood irrigation is widely practiced by the majority of the farmers (more than 85 %) with an efficiency which does not exceed 50%. In this context, a good knowledge of the partitioning of evapotranspiration (ET) into soil evaporation and plant transpiration is of crucial need for improving the irrigation scheduling and thus water use efficiency. In this study, the ISBA (Interactions Soil-Biosphere-Atmosphere) model was used for estimating ET and its partition over an olive orchard and a wheat field located near to the Marrakech City (Centre of Morocco). Two versions were evaluated: standard version which simulates a single energy balance for the soil and vegetation and the recently developed multiple energy balance (MEB) version which solves a separate energy balance for each of the two sources. Eddy covariance system, which provides the sensible and latent heat fluxes and meteorological instruments were operated during years 2003-2004 for the Olive Orchard and during years 2013 for wheat. The transpiration component was measured using a Sap flow system during summer over the wheat crop and stable isotope samples were gathered over wheat. The comparison between ET estimated by ISBA model and that measured by the Eddy covariance system showed that MEB version yielded a remarkable improvement compared to the standard version. The root mean square error (RMSE) and the correlation coefficient (R²) were about 45wm-2 and 0.8 for MEB version. By contrast, for the standard version, the RMSE and R² were about 60wm-2 and 0.7, respectively. The result also showed that

  14. Ecohydrology of Lodgepole Pine Forests: Connecting Transpiration to Subsurface Flow Paths and Storage within a Subalpine Catchment

    Science.gov (United States)

    Byers, A.; Harpold, A. A.; Barnard, H. R.

    2011-12-01

    The hydrologic cycle plays a central role in regulating ecosystem structure and function. Linked studies of both subsurface and aboveground processes are needed to improve understanding of ecosystem changes that could result from climate change and disturbance in Colorado's subalpine forests. Here, we present data from plots dominated by lodgepole pine (Pinus contorta) at the Niwot Ridge LTER site on the Colorado Front Range that improves the process-level understanding of the source and fate of water between subsurface storage and plant uptake. This study utilized event-based sampling during the 2011 growing season to investigate a paradox between water sources and rooting depth in lodgepole pine. Findings from Niwot Ridge have shown that lodgepole, typically believed to be a shallow-rooted species, appear to be strongly dependent on water from snowmelt for the entire growing season. These results suggested that conifer species were accessing water from deeper in the soil than summer monsoon rain typically penetrated. In our study, the relationship between precipitation event size and depth of infiltration on a seasonal and event basis, the effective rooting depth of lodgepole pine, and hysteretic responses of transpiration to soil moisture over a growing season were examined using measurements of tree physiological processes (sap flux and water stress) and hydrological parameters (precipitation, soil moisture) as well as stable water isotope composition of xylem water, mobile and immobile soil water, snow, precipitation, and stream water. Analysis of data shows that soil moisture in deep layers (60 and 70 cm) responds to large summer rain events of 0.7 mm and greater, and that lodgepole sap flux increases by 15-30% within 24 hours of monsoon events and decreases over 72 hours or until subsequent rain. Water isotope analysis will further elucidate the source and event response of these trees. This research helps us understand whether processes known to occur in

  15. Limitations of shallow nets approximation.

    Science.gov (United States)

    Lin, Shao-Bo

    2017-10-01

    In this paper, we aim at analyzing the approximation abilities of shallow networks in reproducing kernel Hilbert spaces (RKHSs). We prove that there is a probability measure such that the achievable lower bound for approximating by shallow nets can be realized for all functions in balls of reproducing kernel Hilbert space with high probability, which is different with the classical minimax approximation error estimates. This result together with the existing approximation results for deep nets shows the limitations for shallow nets and provides a theoretical explanation on why deep nets perform better than shallow nets. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Environmental impact analysis of aquaculture in net cages in a ...

    African Journals Online (AJOL)

    Environmental impact analysis of aquaculture in net cages in a Brazilian water reservoir, based in zooplankton communities. Maria Cristina Crispim, Karla Patrícia Ponte Araújo, Hênio do Nascimento Melo Júnior ...

  17. Shielding calculations for NET

    International Nuclear Information System (INIS)

    Verschuur, K.A.; Hogenbirk, A.

    1991-05-01

    In the European Fusion Technology Programme there is only a small activity on research and development for fusion neutronics. Never-the-less, looking further than blanket design now, as ECN is getting involved in design of radiation shields for the coils and biological shields, it becomes apparent that fusion neutronics as a whole still needs substantial development. Existing exact codes for calculation of complex geometries like MCNP and DORT/TORT are put over the limits of their numerical capabilities, whilst approximate codes for complex geometries like FURNACE and MERCURE4 are put over the limits of their modelling capabilities. The main objective of this study is just to find out how far we can get with existing codes in obtaining reliable values for the radiation levels inside and outside the cryostat/shield during operation and after shut-down. Starting with a 1D torus model for preliminary parametric studies, more dimensional approximation of the torus or parts of it including the main heterogeneities should follow. Regular contacts with the NET-Team are kept, to be aware of main changes in NET design that might affect our calculation models. Work on the contract started 1 July 1990. The technical description of the contract is given. (author). 14 refs.; 4 figs.; 1 tab

  18. Benefits of increasing transpiration efficiency in wheat under elevated CO2 for 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

    2018-05-01

    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.

  19. Thermal Effects on the Body mass, Transpiration rate, Feeding and Food Conversion of the Pillbug Armadillo officinalis (Isopoda, Oniscidea Fed on the Dry Leaf of Punica Granatum

    Directory of Open Access Journals (Sweden)

    Abdelgader K. Youssef

    2004-06-01

    Full Text Available Observations were made on the body mass; transpiration rate; assimilation efficiency; gross and net production efficiencies; feeding, assimilation, conversion and metabolic rates of the pillbug Armadillo officinalis Dumeril acclimatized at 14º  and 21 °C for 15 days and fed on the dry leaf of Punica granatum (Pomegranate.  A brief description is given on the chemical composition of P. granatum leaf.  The difference in body mass increments of A. officinalis between the acclimatized temperatures was not significant (t = 1.09; p>0.05.  However, significant differences were discernible on the transpiration rate (t = 9.53; p<0.01, moisture (t = 9.01; p<0.01, assimilation efficiency (t = 5.16; p<0.01, feeding (t = 3.76; p<0.05 and conversion (t = 2.58; p<0.05  rates between the woodlice acclimatized at 14º and 21 °C.  Better feeding of    P. granatum leaf by these animals was observed at 21° C, but better assimilation efficiency at 14 °C.  Only 3.21% assimilated food at 14° C and 6.30% at 21 °C were converted into the production of new tissues.  The food consumption of A. officinalis at 14º and 21° C was 2.05% and 3.79% body mass/day respectively.  The effect of temperature on the activity of A. officinalis in the field is discussed.

  20. Uncertainty of Wheat Water Use: Simulated Patterns and Sensitivity to Temperature and CO2

    Science.gov (United States)

    Cammarano, Davide; Roetter, Reimund P.; Asseng, Senthold; Ewert, Frank; Wallach, Daniel; Martre, Pierre; Hatfield, Jerry L.; Jones, James W.; Rosenzweig, Cynthia E.; Ruane, Alex C.; hide

    2016-01-01

    Projected global warming and population growth will reduce future water availability for agriculture. Thus, it is essential to increase the efficiency in using water to ensure crop productivity. Quantifying crop water use (WU; i.e. actual evapotranspiration) is a critical step towards this goal. Here, sixteen wheat simulation models were used to quantify sources of model uncertainty and to estimate the relative changes and variability between models for simulated WU, water use efficiency (WUE, WU per unit of grain dry mass produced), transpiration efficiency (Teff, transpiration per kg of unit of grain yield dry mass produced), grain yield, crop transpiration and soil evaporation at increased temperatures and elevated atmospheric carbon dioxide concentrations ([CO2]). The greatest uncertainty in simulating water use, potential evapotranspiration, crop transpiration and soil evaporation was due to differences in how crop transpiration was modelled and accounted for 50 of the total variability among models. The simulation results for the sensitivity to temperature indicated that crop WU will decline with increasing temperature due to reduced growing seasons. The uncertainties in simulated crop WU, and in particularly due to uncertainties in simulating crop transpiration, were greater under conditions of increased temperatures and with high temperatures in combination with elevated atmospheric [CO2] concentrations. Hence the simulation of crop WU, and in particularly crop transpiration under higher temperature, needs to be improved and evaluated with field measurements before models can be used to simulate climate change impacts on future crop water demand.

  1. Leaf water relations and sapflow in eastern cottonwood (Populus deltoides Bartr.) trees planted for phytoremediation of a groundwater pollutant

    Science.gov (United States)

    James M. Vose; Wayne T. Swank; Gregory J. Harvey; Barton D. Clinton; Christine Sobek

    2000-01-01

    Plants that remediate groundwater pollutants may offer a feasible alternative to the traditional and more expensive practices. Because its success depends on water use, this approach requires a complete understanding of species-specific transpiration patterns. The objectives of this study were (1) to quantify tree and stand-level transpiration in two age classes (whips...

  2. The water-filled versus air-filled status of vessels cut open in air: the 'Scholander assumption' revisited

    Science.gov (United States)

    M.T. Tyree; H. Cochard; P. Cruziat

    2003-01-01

    When petioles of transpiring leaves are cut in the air, according to the 'Scholander assumption', the vessels cut open should fill with air as the water is drained away by continued transpiration, The distribution of air-filled vessels versus distance from the cut surface should match the distribution of lengths of 'open vessels', i.e. vessels cut...

  3. Overproduction of abscisic acid in tomato increases transpiration efficiency and root hydraulic conductivity and influences leaf expansion.

    Science.gov (United States)

    Thompson, Andrew J; Andrews, John; Mulholland, Barry J; McKee, John M T; Hilton, Howard W; Horridge, Jon S; Farquhar, Graham D; Smeeton, Rachel C; Smillie, Ian R A; Black, Colin R; Taylor, Ian B

    2007-04-01

    Overexpression of genes that respond to drought stress is a seemingly attractive approach for improving drought resistance in crops. However, the consequences for both water-use efficiency and productivity must be considered if agronomic utility is sought. Here, we characterize two tomato (Solanum lycopersicum) lines (sp12 and sp5) that overexpress a gene encoding 9-cis-epoxycarotenoid dioxygenase, the enzyme that catalyzes a key rate-limiting step in abscisic acid (ABA) biosynthesis. Both lines contained more ABA than the wild type, with sp5 accumulating more than sp12. Both had higher transpiration efficiency because of their lower stomatal conductance, as demonstrated by increases in delta(13)C and delta(18)O, and also by gravimetric and gas-exchange methods. They also had greater root hydraulic conductivity. Under well-watered glasshouse conditions, mature sp5 plants were found to have a shoot biomass equal to the wild type despite their lower assimilation rate per unit leaf area. These plants also had longer petioles, larger leaf area, increased specific leaf area, and reduced leaf epinasty. When exposed to root-zone water deficits, line sp12 showed an increase in xylem ABA concentration and a reduction in stomatal conductance to the same final levels as the wild type, but from a different basal level. Indeed, the main difference between the high ABA plants and the wild type was their performance under well-watered conditions: the former conserved soil water by limiting maximum stomatal conductance per unit leaf area, but also, at least in the case of sp5, developed a canopy more suited to light interception, maximizing assimilation per plant, possibly due to improved turgor or suppression of epinasty.

  4. NETS - Danish participation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Alsen, S. (Grontmij - Carl Bro, Glostrup (Denmark)); Theel, C. (Baltic Sea Solutions, Holeby (Denmark))

    2008-12-15

    Within the NICe-funded project 'Nordic Environmental Technology Solutions (NETS)' a new type of networking at the Nordic level was organized in order to jointly exploit the rapidly growing market potential in the environmental technology sector. The project aimed at increased and professionalized commercialization of Nordic Cleantech in energy and water business segments through 1) closer cooperation and joint marketing activities, 2) a website, 3) cleantech product information via brochures and publications 4) and participating in relevant trade fairs and other industry events. Facilitating business-to-business activities was another core task for the NETS project partners from Norway, Sweden, Finland and Denmark with the aim to encourage total solutions for combined Cleantech system offers. The project has achieved to establish a Cleantech register of 600 Nordic Cleantech companies, a network of 86 member enterprises, produced several publications and brochures for direct technology promotion and a website for direct access to company profiles and contact data. The project partners have attended 14 relevant international Cleantech trade fairs and conferences and facilitated business-to-business contacts added by capacity building offers through two company workshops. The future challenge for the project partners and Nordic Cleantech will be to coordinate the numerous efforts within the Nordic countries in order to reach concerted action and binding of member companies for reliable services, an improved visibility and knowledge exchange. With Cleantech's growing market influence and public awareness, the need to develop total solutions is increasing likewise. Marketing efforts should be encouraged cross-sectional and cross-border among the various levels of involved actors from both the public and the private sector. (au)

  5. NETS - Danish participation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Alsen, S [Grontmij - Carl Bro, Glostrup (Denmark); Theel, C [Baltic Sea Solutions, Holeby (Denmark)

    2008-12-15

    Within the NICe-funded project 'Nordic Environmental Technology Solutions (NETS)' a new type of networking at the Nordic level was organized in order to jointly exploit the rapidly growing market potential in the environmental technology sector. The project aimed at increased and professionalized commercialization of Nordic Cleantech in energy and water business segments through 1) closer cooperation and joint marketing activities, 2) a website, 3) cleantech product information via brochures and publications 4) and participating in relevant trade fairs and other industry events. Facilitating business-to-business activities was another core task for the NETS project partners from Norway, Sweden, Finland and Denmark with the aim to encourage total solutions for combined Cleantech system offers. The project has achieved to establish a Cleantech register of 600 Nordic Cleantech companies, a network of 86 member enterprises, produced several publications and brochures for direct technology promotion and a website for direct access to company profiles and contact data. The project partners have attended 14 relevant international Cleantech trade fairs and conferences and facilitated business-to-business contacts added by capacity building offers through two company workshops. The future challenge for the project partners and Nordic Cleantech will be to coordinate the numerous efforts within the Nordic countries in order to reach concerted action and binding of member companies for reliable services, an improved visibility and knowledge exchange. With Cleantech's growing market influence and public awareness, the need to develop total solutions is increasing likewise. Marketing efforts should be encouraged cross-sectional and cross-border among the various levels of involved actors from both the public and the private sector. (au)

  6. The equivalency between logic Petri workflow nets and workflow nets.

    Science.gov (United States)

    Wang, Jing; Yu, ShuXia; Du, YuYue

    2015-01-01

    Logic Petri nets (LPNs) can describe and analyze batch processing functions and passing value indeterminacy in cooperative systems. Logic Petri workflow nets (LPWNs) are proposed based on LPNs in this paper. Process mining is regarded as an important bridge between modeling and analysis of data mining and business process. Workflow nets (WF-nets) are the extension to Petri nets (PNs), and have successfully been used to process mining. Some shortcomings cannot be avoided in process mining, such as duplicate tasks, invisible tasks, and the noise of logs. The online shop in electronic commerce in this paper is modeled to prove the equivalence between LPWNs and WF-nets, and advantages of LPWNs are presented.

  7. The Equivalency between Logic Petri Workflow Nets and Workflow Nets

    Science.gov (United States)

    Wang, Jing; Yu, ShuXia; Du, YuYue

    2015-01-01

    Logic Petri nets (LPNs) can describe and analyze batch processing functions and passing value indeterminacy in cooperative systems. Logic Petri workflow nets (LPWNs) are proposed based on LPNs in this paper. Process mining is regarded as an important bridge between modeling and analysis of data mining and business process. Workflow nets (WF-nets) are the extension to Petri nets (PNs), and have successfully been used to process mining. Some shortcomings cannot be avoided in process mining, such as duplicate tasks, invisible tasks, and the noise of logs. The online shop in electronic commerce in this paper is modeled to prove the equivalence between LPWNs and WF-nets, and advantages of LPWNs are presented. PMID:25821845

  8. Mesoporous Silica Molecular Sieve based Nanocarriers: Transpiring Drug Dissolution Research.

    Science.gov (United States)

    Pattnaik, Satyanarayan; Pathak, Kamla

    2017-01-01

    Improvement of oral bioavailability through enhancement of dissolution for poorly soluble drugs has been a very promising approach. Recently, mesoporous silica based molecular sieves have demonstrated excellent properties to enhance the dissolution velocity of poorly water-soluble drugs. Current research in this area is focused on investigating the factors influencing the drug release from these carriers, the kinetics of drug release and manufacturing approaches to scale-up production for commercial manufacture. This comprehensive review provides an overview of different methods adopted for synthesis of mesoporous materials, influence of processing factors on properties of these materials and drug loading methods. The drug release kinetics from mesoporous silica systems, the manufacturability and stability of these formulations are reviewed. Finally, the safety and biocompatibility issues related to these silica based materials are discussed. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  9. Alternative perspective on the control of transpiration by radiation.

    Science.gov (United States)

    Mott, Keith A; Peak, David

    2011-12-06

    Stomatal responses to light are important determinants for plant water use efficiency and for general circulation models, but a mechanistic understanding of these responses remains elusive. A recent study [Pieruschka R, Huber G, Berry JA (2010) Proc Natl Acad Sci USA 107:13372-13377] concluded that stomata respond to total absorbed radiation rather than red and blue light as previously thought. We tested this idea by reexamining stomatal responses to red and blue light and to IR radiation. We show that responses to red and blue light are not consistent with a response to total absorbed radiation and that apparent stomatal responses to IR radiation are explainable as experimental artifacts. In addition, our data and analysis provide a method for accurately determining the internal temperature of a leaf.

  10. Art/Net/Work

    DEFF Research Database (Denmark)

    Andersen, Christian Ulrik; Lindstrøm, Hanne

    2006-01-01

    The seminar Art|Net|Work deals with two important changes in our culture. On one side, the network has become essential in the latest technological development. The Internet has entered a new phase, Web 2.0, including the occurrence of as ‘Wiki’s’, ‘Peer-2-Peer’ distribution, user controlled...... on the ‘network’ itself as a phenomenon and are often using technological networks as a mean of production and distribution. This changes the artistic practice and the distribution channels of art works – and the traditional notions of ‘work’, ‘origin’ and ‘rights’ are increasingly perceived as limiting...... the praxis of the artist. We see different kinds of interventions and activism (including ‘hacktivism’) using the network as a way of questioning the invisible rules that govern public and semi-public spaces. Who ‘owns’ them? What kind of social relationships do they generate? On what principle...

  11. Net4Care

    DEFF Research Database (Denmark)

    Christensen, Henrik Bærbak; Hansen, Klaus Marius

    2012-01-01

    , health centers are getting larger and more distributed, and the number of healthcare professionals does not follow the trend in chronic diseases. All of this leads to a need for telemedical and mobile health applications. In a Danish context, these applications are often developed through local...... (innovative) initiatives with little regards for national and global (standardization) initiatives. A reason for this discrepancy is that the software architecture for national (and global) systems and standards are hard to understand, hard to develop systems based on, and hard to deploy. To counter this, we...... propose a software ecosystem approach for telemedicine applications, providing a framework, Net4Care, encapsulating national/global design decisions with respect to standardization while allowing for local innovation. This paper presents an analysis of existing systems, of requirements for a software...

  12. Diurnal variations in water relations of deficit irrigated lemon trees during fruit growth period

    Directory of Open Access Journals (Sweden)

    Y. García-Orellana

    2013-01-01

    Full Text Available Field-grown lemon trees (Citrus limon (L. Burm. fil. cv. Fino were subjected to different drip irrigation treatments: a control treatment, irrigated daily above crop water requirements in order to obtain non-limiting soil water conditions and two deficit irrigation treatments, reducing the water applied according to the maximum daily trunk shrinkage (MDS signal intensity (actual MDS/control treatment MDS threshold values of 1.25 (T1 treatment and 1.35 (T2 treatment, which induced two different drought stress levels