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Sample records for transpiration leaf diffusive

  1. 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...

  2. 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.

  3. 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.

  4. 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

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

    Science.gov (United States)

    Locke, Anna M.; Ort, Donald R.

    2014-01-01

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

  6. 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.)

  7. 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

  8. 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 ...

  9. 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...

  10. 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.

  11. 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.

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

    International Nuclear Information System (INIS)

    Ito, D.; Haseba, T.

    1984-01-01

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

  13. Cross-scale modelling of transpiration from stomata via the leaf boundary layer

    Science.gov (United States)

    Defraeye, Thijs; Derome, Dominique; Verboven, Pieter; Carmeliet, Jan; Nicolai, Bart

    2014-01-01

    Background and Aims Leaf transpiration is a key parameter for understanding land surface–climate interactions, plant stress and plant structure–function relationships. Transpiration takes place at the microscale level, namely via stomata that are distributed discretely over the leaf surface with a very low surface coverage (approx. 0·2–5 %). The present study aims to shed more light on the dependency of the leaf boundary-layer conductance (BLC) on stomatal surface coverage and air speed. Methods An innovative three-dimensional cross-scale modelling approach was applied to investigate convective mass transport from leaves, using computational fluid dynamics. The gap between stomatal and leaf scale was bridged by including all these scales in the same computational model (10−5–10−1 m), which implies explicitly modelling individual stomata. Key Results BLC was strongly dependent on stomatal surface coverage and air speed. Leaf BLC at low surface coverage ratios (CR), typical for stomata, was still relatively high, compared with BLC of a fully wet leaf (hypothetical CR of 100 %). Nevertheless, these conventional BLCs (CR of 100 %), as obtained from experiments or simulations on leaf models, were found to overpredict the convective exchange. In addition, small variations in stomatal CR were found to result in large variations in BLCs. Furthermore, stomata of a certain size exhibited a higher mass transfer rate at lower CRs. Conclusions The proposed cross-scale modelling approach allows us to increase our understanding of transpiration at the sub-leaf level as well as the boundary-layer microclimate in a way currently not feasible experimentally. The influence of stomatal size, aperture and surface density, and also flow-field parameters can be studied using the model, and prospects for further improvement of the model are presented. An important conclusion of the study is that existing measures of conductances (e.g. from artificial leaves) can be

  14. 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.

  15. Leaf transpiration plays a role in phosphorus acquisition among a large set of chickpea genotypes.

    Science.gov (United States)

    Pang, Jiayin; Zhao, Hongxia; Bansal, Ruchi; Bohuon, Emilien; Lambers, Hans; Ryan, Megan H; Siddique, Kadambot H M

    2018-01-09

    Low availability of inorganic phosphorus (P) is considered a major constraint for crop productivity worldwide. A unique set of 266 chickpea (Cicer arietinum L.) genotypes, originating from 29 countries and with diverse genetic background, were used to study P-use efficiency. Plants were grown in pots containing sterilized river sand supplied with P at a rate of 10 μg P g -1 soil as FePO 4 , a poorly soluble form of P. The results showed large genotypic variation in plant growth, shoot P content, physiological P-use efficiency, and P-utilization efficiency in response to low P supply. Further investigation of a subset of 100 chickpea genotypes with contrasting growth performance showed significant differences in photosynthetic rate and photosynthetic P-use efficiency. A positive correlation was found between leaf P concentration and transpiration rate of the young fully expanded leaves. For the first time, our study has suggested a role of leaf transpiration in P acquisition, consistent with transpiration-driven mass flow in chickpea grown in low-P sandy soils. The identification of 6 genotypes with high plant growth, P-acquisition, and P-utilization efficiency suggests that the chickpea reference set can be used in breeding programmes to improve both P-acquisition and P-utilization efficiency under low-P conditions. © 2018 John Wiley & Sons Ltd.

  16. 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

  17. 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...

  18. Abscisic Acid Content, Transpiration, and Stomatal Conductance As Related to Leaf Age in Plants of Xanthium strumarium L.

    Science.gov (United States)

    Raschke, K; Zeevaart, J A

    1976-08-01

    Among the four uppermost leaves of greenhouse-grown plants of Xanthium strumarium L. the content of abscisic acid per unit fresh or dry weight was highest in the youngest leaf and decreased gradually with increasing age of the leaves. Expressed per leaf, the second youngest leaf was richest in ABA; the amount of ABA per leaf declined only slightly as the leaves expanded. Transpiration and stomatal conductance were negatively correlated with the ABA concentration in the leaves; the youngest leaf lost the least amount of water. This correlation was always very good if the youngest leaf was compared with the older leaves but not always good among the older leaves. Since stomatal sensitivity to exogenous (+/-)-ABA was the same in leaves of all four age groups ABA may be in at least two compartments in the leaf, one of which is isolated from the guard cells.The ability to synthesize ABA in response to wilting or chilling was strongly expressed in young leaves and declined with leaf age. There was no difference between leaves in their content of the metabolites of ABA, phaseic, and dihydrophaseic acid, expressed per unit weight.

  19. Abscisic Acid Content, Transpiration, and Stomatal Conductance As Related to Leaf Age in Plants of Xanthium strumarium L. 1

    Science.gov (United States)

    Raschke, Klaus; Zeevaart, Jan A. D.

    1976-01-01

    Among the four uppermost leaves of greenhouse-grown plants of Xanthium strumarium L. the content of abscisic acid per unit fresh or dry weight was highest in the youngest leaf and decreased gradually with increasing age of the leaves. Expressed per leaf, the second youngest leaf was richest in ABA; the amount of ABA per leaf declined only slightly as the leaves expanded. Transpiration and stomatal conductance were negatively correlated with the ABA concentration in the leaves; the youngest leaf lost the least amount of water. This correlation was always very good if the youngest leaf was compared with the older leaves but not always good among the older leaves. Since stomatal sensitivity to exogenous (±)-ABA was the same in leaves of all four age groups ABA may be in at least two compartments in the leaf, one of which is isolated from the guard cells. The ability to synthesize ABA in response to wilting or chilling was strongly expressed in young leaves and declined with leaf age. There was no difference between leaves in their content of the metabolites of ABA, phaseic, and dihydrophaseic acid, expressed per unit weight. PMID:16659640

  20. Effect of incident beam and diffuse radiation on par absorption, photosynthesis and transpiration of sitka spruce - a simulation study

    International Nuclear Information System (INIS)

    Wang, Y.P.; Jarvis, P.G.

    1990-01-01

    A simulation model, Maestro, is used to study the influence of beam fraction in the incident radiation and the radiance distribution of the sky diffuse radiation on PAR absorption, photosynthesis and transpiration of a Sitka spruce (Picea sitchensis (Bong.) Carr) tree crown. It is concluded that inaccurate separation of beam and diffuse radiation leads to significant errors in estimating the amounts of PAR absorbed, photosynthesis and transpiration by a tree in the stand. Much more attention should be paid to adequate descriptions of the radiance distribution of the sky diffuse radiation under different sky conditions. A useful approach is proposed for simulating the incident global radiaiton in a physiological, process-based model

  1. 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

  2. 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.

  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. What determines the complex kinetics of stomatal conductance under blueless PAR in Festuca arundinacea? Subsequent effects on leaf transpiration.

    Science.gov (United States)

    Barillot, Romain; Frak, Ela; Combes, Didier; Durand, Jean-Louis; Escobar-Gutiérrez, Abraham J

    2010-06-01

    Light quality and, in particular, its content of blue light is involved in plant functioning and morphogenesis. Blue light variation frequently occurs within a stand as shaded zones are characterized by a simultaneous decrease of PAR and blue light levels which both affect plant functioning, for example, gas exchange. However, little is known about the effects of low blue light itself on gas exchange. The aims of the present study were (i) to characterize stomatal behaviour in Festuca arundinacea leaves through leaf gas exchange measurements in response to a sudden reduction in blue light, and (ii) to test the putative role of Ci on blue light gas exchange responses. An infrared gas analyser (IRGA) was used with light transmission filters to study stomatal conductance (gs), transpiration (Tr), assimilation (A), and intercellular concentration of CO(2) (Ci) responses to blueless PAR (1.80 mumol m(-2) s(-1)). The results were compared with those obtained under a neutral filter supplying a similar photosynthetic efficiency to the blueless PAR filter. It was shown that the reduction of blue light triggered a drastic and instantaneous decrease of gs by 43.2% and of Tr by 40.0%, but a gradual stomatal reopening began 20 min after the start of the low blue light treatment, thus leading to new steady-states. This new stomatal equilibrium was supposed to be related to Ci. The results were confirmed in more developed plants although they exhibited delayed and less marked responses. It is concluded that stomatal responses to blue light could play a key role in photomorphogenetic mechanisms through their effect on transpiration.

  5. 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.

  6. 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.

  7. 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.

  8. Stomatal conductance, mesophyll conductance, and transpiration efficiency in relation to leaf anatomy in rice and wheat genotypes under drought.

    Science.gov (United States)

    Ouyang, Wenjing; Struik, Paul C; Yin, Xinyou; Yang, Jianchang

    2017-11-02

    Increasing leaf transpiration efficiency (TE) may provide leads for growing rice like dryland cereals such as wheat (Triticum aestivum). To explore avenues for improving TE in rice, variations in stomatal conductance (gs) and mesophyll conductance (gm) and their anatomical determinants were evaluated in two cultivars from each of lowland, aerobic, and upland groups of Oryza sativa, one cultivar of O. glaberrima, and two cultivars of T. aestivum, under three water regimes. The TE of upland rice, O. glaberrima, and wheat was more responsive to the gm/gs ratio than that of lowland and aerobic rice. Overall, the explanatory power of the particular anatomical trait varied among species. Low stomatal density mostly explained the low gs in drought-tolerant rice, whereas rice genotypes with smaller stomata generally responded more strongly to drought. Compared with rice, wheat had a higher gm, which was associated with thicker mesophyll tissue, mesophyll and chloroplasts more exposed to intercellular spaces, and thinner cell walls. Upland rice, O. glaberrima, and wheat cultivars minimized the decrease in gm under drought by maintaining high ratios of chloroplasts to exposed mesophyll cell walls. Rice TE could be improved by increasing the gm/gs ratio via modifying anatomical traits. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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...

  17. 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.

  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. 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.

  20. 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

  1. 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.

  2. [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.

  3. 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)

  4. Transpiração e temperatura foliar da cana-de-açúcar sob diferentes valores de potencial matricial Transpiration and leaf temperature of sugarcane under different matric potential values

    Directory of Open Access Journals (Sweden)

    Roberto Trentin

    2011-12-01

    Full Text Available O objetivo deste trabalho foi avaliar a variação diurna da transpiração e da temperatura foliar da cana-de-açúcar, cv. RB867515, sob diferentes potenciais matriciais de água no substrato de cultivo e as condições meteorológicas em ambiente protegido. O efeito do estresse hídrico na transpiração e temperatura foliar foi determinado a partir da suspensão da irrigação, quando foram realizadas três campanhas de medições, iniciadas aos 122; 150 e 185 dias após o plantio (DAP até que o potencial matricial de água no substrato (Ψ alcançasse -1.500 kPa, aproximadamente. Sob ausência de estresse hídrico (Ψ>-50 kPa, a transpiração das plantas atingiu o valor máximo entre 10 e 13 h, próximo de 60; 70 e 100 g planta-1 h-1 para 122; 150 e 185 DAP, respectivamente. Sob condições de estresse hídrico severo (ΨThe objective of this study was to evaluate the diurnal behaviour of transpiration and leaf temperature of sugarcane (cv. RB867515 under different water matrix potential in the cultivation substrate and greenhouse meteorological conditions. The water stress effect on transpiration and leaf temperature was determined after irrigation suspension, when three measurement campaigns were initiated at 122; 150 and 185 days after planting (DAP until the matrix water potential in the substrate (Ψ reached -1,500 kPa, approximately. Under the absence of water stress (Ψ>-50 kPa, plant transpiration reached the maximum value between 10:00 AM and 13:00 PM, near to 60; 70 e 100 gplant-1h-1, for 122; 150 and 185 DAP, respectively. Under severe water stress (Ψ<-1,100 kPa, there was daily transpiration reduction of approximately 73%, compared to measurements performed without water stress and under similar meteorological conditions. Under the absence of water stress and overcast sky conditions, the average value of the difference between leaf temperature and air temperature was -2.9 ºC. In contrast, under severe water stress and high

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. Sap flux-scaled transpiration by tamarisk (Tamarix spp.) before, during and after episodic defoliation by the saltcedar leaf beetle (Diorhabda carinulata)

    Science.gov (United States)

    Hultine, K.R.; Nagler, P.L.; Morino, K.; Bush, S.E.; Burtch, K.G.; Dennison, P.E.; Glenn, E.P.; Ehleringer, J.R.

    2010-01-01

    The release of the saltcedar beetle (Diorhabda carinulata) has resulted in the periodic defoliation of tamarisk (Tamarix spp.) along more than 1000 river km in the upper Colorado River Basin and is expected to spread along many other river reaches throughout the upper basin, and possibly into the lower Colorado River Basin. Identifying the impacts of these release programs on tamarisk water use and subsequent water cycling in arid riparian systems are largely unknown, due in part to the difficulty of measuring water fluxes in these systems. We used lab-calibrated, modified heat-dissipation sap flux sensors to monitor tamarisk water use (n=20 trees) before, during and after defoliation by the saltcedar leaf beetle during the 2008 and 2009 growing seasons (May-October) in southeastern Utah. We incorporated a simple model that related mean stem sap flux density (Js) with atmospheric vapor pressure deficit (vpd) before the onset of defoliation in 2008. The model was used to calculate differences between predicted Js and Js measured throughout the two growing seasons. Episodic defoliation resulted in a 16% reduction in mean annual rates of Js in both 2008 and 2009, with decreases occurring only during the periods in which the trees were defoliated (about 6-8 weeks per growing season). In other words, rates of Js rebounded to values predicted by the model when the trees produced new leaves after defoliation. Sap flux data were scaled to stand water use by constructing a tamarisk-specific allometric equation to relate conducting sapwood area to stem diameter, and by measuring the size distribution of stems within the stand. Total water use in both years was 0.224m, representing a reduction of about 0.04myr-1. Results showed that repeated defoliation/refoliation cycles did not result in a progressive decrease in either leaf production or water use over the duration of the study. This investigation improves ground-based estimates of tamarisk water use, and will support

  10. 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

  11. Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species?

    Directory of Open Access Journals (Sweden)

    BRUNO H.P. ROSADO

    2013-09-01

    Full Text Available During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models.

  12. Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species?

    Science.gov (United States)

    Rosado, Bruno H P; De Mattos, Eduardo A; Sternberg, Leonel Da S L

    2013-09-01

    During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models.

  13. 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.

  14. 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.

  15. Relações entre transpiração máxima, evapotranspiração de referência e área foliar em quatro variedades de mangueira Maximum transpiration, reference evapotranspiration and leaf area relationships for some mango cultivars

    Directory of Open Access Journals (Sweden)

    Greice Ximena Santos Oliveira

    2009-03-01

    Full Text Available Nas condições edafoclimáticas de Cruz da Almas - BA, na Embrapa Mandioca e Fruticultura Tropical, foi realizado um estudo no qual se relacionou a transpiração máxima (Litros m-2 folha/dia -1 de quatro variedades de mangueira (Tommy Atkins, Palmer, Haden e Van Dyke, com áreas foliares totais de 14; 8; 33 e 12 m², respectivamente com a evapotranspiração de referência (ETo. A transpiração das plantas (L dia-1 foi estimada por meio de sensores que realizam o balanço de calor no caule (modelos SAG13; SGB9; SGB16; SGB19 e SGB25, Dynamax Inc. dispostos nos sentidos norte (N, sul (S, leste (E, oeste (W e centro (C de cada planta. A transpiração por unidade de área foliar (Lm-2 folha dia-1 variou em média de 1,58 ao longo do período estudado, e linearmente com o aumento da área foliar total da planta, independentemente da variedade estudada. A transpiração (Litros m-2 folha/dia -1 variou de 0,36 a 3,00, dependendo da demanda atmosférica. A transpiração máxima (T das quatro variedades de mangueira (Litros m-2 folha/dia -1 relacionouse linearmente com a ETo (T = 0,44. ETo; r² = 0,78, sendo um excelente subsídio para o manejo de irrigação por gotejamento nesta cultura.A study relating maximum transpiration (L m-2 leaf day-1 to reference evapotranspiration (ETo for four mango cultivars (Tommy Atkins, Palmer, Haden and Van Dyke, with 14 m², 8 m², 33 m² and 12 m² of leaf area, respectively was carried out at Embrapa Cassava and Tropical Fruits, in the conditions of Cruz da Almas-BA. Plant transpiration (L. day-1 was estimated by heat balance sensors that were installed on the shoots (models SAG13; SGB9; SGB16; SGB19 e SGB25, Dynamax Inc.. The sensors were installed to the North (N, South (S, East (E, West (W and Center(C of each plant. The transpiration per unity leaf area (L.m-2.day-1 varied about 1.58 in average along the studied period and it also varied linearly with the increase in total leaf area, regardless the studied

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. Separating foliar physiology from morphology reveals the relative roles of vertically structured transpiration factors within red maple crowns and limitations of larger scale models

    Science.gov (United States)

    Bauerle, William L.; Bowden, Joseph D.

    2011-01-01

    A spatially explicit mechanistic model, MAESTRA, was used to separate key parameters affecting transpiration to provide insights into the most influential parameters for accurate predictions of within-crown and within-canopy transpiration. Once validated among Acer rubrum L. genotypes, model responses to different parameterization scenarios were scaled up to stand transpiration (expressed per unit leaf area) to assess how transpiration might be affected by the spatial distribution of foliage properties. For example, when physiological differences were accounted for, differences in leaf width among A. rubrum L. genotypes resulted in a 25% difference in transpiration. An in silico within-canopy sensitivity analysis was conducted over the range of genotype parameter variation observed and under different climate forcing conditions. The analysis revealed that seven of 16 leaf traits had a ≥5% impact on transpiration predictions. Under sparse foliage conditions, comparisons of the present findings with previous studies were in agreement that parameters such as the maximum Rubisco-limited rate of photosynthesis can explain ∼20% of the variability in predicted transpiration. However, the spatial analysis shows how such parameters can decrease or change in importance below the uppermost canopy layer. Alternatively, model sensitivity to leaf width and minimum stomatal conductance was continuous along a vertical canopy depth profile. Foremost, transpiration sensitivity to an observed range of morphological and physiological parameters is examined and the spatial sensitivity of transpiration model predictions to vertical variations in microclimate and foliage density is identified to reduce the uncertainty of current transpiration predictions. PMID:21617246

  4. A Novel Diffuse Fraction-Based Two-Leaf Light Use Efficiency Model: An Application Quantifying Photosynthetic Seasonality across 20 AmeriFlux Flux Tower Sites

    Science.gov (United States)

    Yan, Hao; Wang, Shao-Qiang; Yu, Kai-Liang; Wang, Bin; Yu, Qin; Bohrer, Gil; Billesbach, Dave; Bracho, Rosvel; Rahman, Faiz; Shugart, Herman H.

    2017-10-01

    Diffuse radiation can increase canopy light use efficiency (LUE). This creates the need to differentiate the effects of direct and diffuse radiation when simulating terrestrial gross primary production (GPP). Here, we present a novel GPP model, the diffuse-fraction-based two-leaf model (DTEC), which includes the leaf response to direct and diffuse radiation, and treats maximum LUE for shaded leaves (ɛmsh defined as a power function of the diffuse fraction (Df)) and sunlit leaves (ɛmsu defined as a constant) separately. An Amazonian rainforest site (KM67) was used to calibrate the model by simulating the linear relationship between monthly canopy LUE and Df. This showed a positive response of forest GPP to atmospheric diffuse radiation, and suggested that diffuse radiation was more limiting than global radiation and water availability for Amazon rainforest GPP on a monthly scale. Further evaluation at 20 independent AmeriFlux sites showed that the DTEC model, when driven by monthly meteorological data and MODIS leaf area index (LAI) products, explained 70% of the variability observed in monthly flux tower GPP. This exceeded the 51% accounted for by the MODIS 17A2 big-leaf GPP product. The DTEC model's explicit accounting for the impacts of diffuse radiation and soil water stress along with its parameterization for C4 and C3 plants was responsible for this difference. The evaluation of DTEC at Amazon rainforest sites demonstrated its potential to capture the unique seasonality of higher GPP during the diffuse radiation-dominated wet season. Our results highlight the importance of diffuse radiation in seasonal GPP simulation.Plain Language SummaryAs diffuse radiation can increase canopy light use efficiency (LUE), there is a need to differentiate the effects of direct and diffuse radiation in simulating terrestrial gross primary production (GPP). A novel diffuse-fraction (Df)-based two leaf GPP model (DTEC) developed by this study considers these effects. Evaluation

  5. Fruit load governs transpiration of olive trees.

    Science.gov (United States)

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

    2016-03-01

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

  6. SOUND TRANSMISSION LOSS OF A DOUBLE-LEAF PARTITION WITH MICRO-PERFORATED PLATE INSERTION UNDER DIFFUSE FIELD INCIDENCE

    Directory of Open Access Journals (Sweden)

    A. Putra

    2013-06-01

    Full Text Available In noise control applications, a double-leaf partition has been applied widely as a lightweight structure for noise insulation, such as in car doors, train bodies, and aircraft fuselages. Unfortunately, the insulation performance deteriorates significantly at mass-air-mass resonance due to coupling between the panels and the air in the gap. This paper investigates the effect of a micro-perforated panel (MPP, inserted in the conventional double-panel partition, on sound transmission loss at troublesome resonant frequencies. It is found that the transmission loss improves at this resonance if the MPP is located at a distance of less than half that of the air gap. A mathematical model is derived for the diffuse field incidence of acoustic loading.

  7. Effects of diffuse radiation on canopy gas exchange processes in a forest ecosystem

    Science.gov (United States)

    Knohl, Alexander; Baldocchi, Dennis D.

    2008-06-01

    Forest ecosystems across the globe show an increase in ecosystem carbon uptake efficiency under conditions with high fraction of diffuse radiation. Here, we combine eddy covariance flux measurements at a deciduous temperate forest in central Germany with canopy-scale modeling using the biophysical multilayer model CANVEG to investigate the impact of diffuse radiation on various canopy gas exchange processes and to elucidate the underlying mechanisms. Increasing diffuse radiation enhances canopy photosynthesis by redistributing the solar radiation load from light saturated sunlit leaves to nonsaturated shade leaves. Interactions with atmospheric vapor pressure deficit and reduced leaf respiration are only of minor importance to canopy photosynthesis. The response strength of carbon uptake to diffuse radiation depends on canopy characteristics such as leaf area index and leaf optical properties. Our model computations shows that both canopy photosynthesis and transpiration increase initially with diffuse fraction, but decrease after an optimum at a diffuse fraction of 0.45 due to reduction in global radiation. The initial increase in canopy photosynthesis exceeds the increase in transpiration, leading to a rise in water-use-efficiency. Our model predicts an increase in carbon isotope discrimination with water-use-efficiency resulting from differences in the leaf-to-air vapor pressure gradient and atmospheric vapor pressure deficit. This finding is in contrast to those predicted with simple big-leaf models that do not explicitly calculate leaf energy balance. At an annual scale, we estimate a decrease in annual carbon uptake for a potential increase in diffuse fraction, since diffuse fraction was beyond the optimum for 61% of the data.

  8. A natural carbonized leaf as polysulfide diffusion inhibitor for high-performance lithium-sulfur battery cells.

    Science.gov (United States)

    Chung, Sheng-Heng; Manthiram, Arumugam

    2014-06-01

    Attracted by the unique tissue and functions of leaves, a natural carbonized leaf (CL) is presented as a polysulfide diffusion inhibitor in lithium-sulfur (Li-S) batteries. The CL that is covered on the pure sulfur cathode effectively suppresses the polysulfide shuttling mechanism and enables the use of pure sulfur as the cathode. A low charge resistance and a high discharge capacity of 1320 mA h g(-1) arise from the improved cell conductivity due to the innately integral conductive carbon network of the CL. The unique microstructure of CL leads to a high discharge/charge efficiency of >98 %, low capacity fade of 0.18 % per cycle, and good long-term cyclability over 150 cycles. The structural gradient and the micro/mesoporous adsorption sites of CL effectively intercept/trap the migrating polysulfides and facilitate their reutilization. The green CL polysulfide diffusion inhibitor thus offers a viable approach for developing high-performance lithium-sulfur batteries. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. 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.

  10. 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

  11. Diffusion

    International Nuclear Information System (INIS)

    Kubaschewski, O.

    1983-01-01

    The diffusion rate values of titanium, its compounds and alloys are summarized and tabulated. The individual chemical diffusion coefficients and self-diffusion coefficients of certain isotopes are given. Experimental methods are listed which were used for the determination of diffusion coefficients. Some values have been taken over from other studies. Also given are graphs showing the temperature dependences of diffusion and changes in the diffusion coefficient with concentration changes

  12. 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...

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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

  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. 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....

  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. 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. 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...

  4. 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.

  5. 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

  6. 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.

  7. Quantifying structural and physiological controls on variation in canopy transpiration among planted pine and hardwood species in the southern Appalachians

    Science.gov (United States)

    Chelcy R. Ford; Robert M. Hubbard; James M. Vose

    2010-01-01

    Recent studies have shown that planted pine stands exhibit higher evapotranspiration (ET) and are more sensitive to climatic conditions compared with hardwood stands. Whether this is due to management and stand effects, biological effects or their interaction is poorly understood. We estimated growing season canopy- and sap flux-scaled leaf-level transpiration (Ec and...

  8. Effects of above- and below-ground competition from shrubs on photosynthesis, transpiration and growth in Quercus robur L

    Science.gov (United States)

    Anna M. Jensen; Magnus Lof; Emile S. Gardiner

    2011-01-01

    For a tree seedling to successfully establish in dense shrubbery, it must maintain function under heterogeneous resource availability. We evaluated leaf-level acclimation in photosynthetic capacity, seedling-level transpiration, and seedling morphology and growth to gain an understanding of the effects of above- and below-ground competition on Quercus robur seedlings....

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. Wind increases leaf water use efficiency.

    Science.gov (United States)

    Schymanski, Stanislaus J; Or, Dani

    2016-07-01

    A widespread perception is that, with increasing wind speed, transpiration from plant leaves increases. However, evidence suggests that increasing wind speed enhances carbon dioxide (CO2 ) uptake while reducing transpiration because of more efficient convective cooling (under high solar radiation loads). We provide theoretical and experimental evidence that leaf water use efficiency (WUE, carbon uptake per water transpired) commonly increases with increasing wind speed, thus improving plants' ability to conserve water during photosynthesis. Our leaf-scale analysis suggests that the observed global decrease in near-surface wind speeds could have reduced WUE at a magnitude similar to the increase in WUE attributed to global rise in atmospheric CO2 concentrations. However, there is indication that the effect of long-term trends in wind speed on leaf gas exchange may be compensated for by the concurrent reduction in mean leaf sizes. These unintuitive feedbacks between wind, leaf size and water use efficiency call for re-evaluation of the role of wind in plant water relations and potential re-interpretation of temporal and geographic trends in leaf sizes. © 2015 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.

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

    Directory of Open Access Journals (Sweden)

    Mantovani Dario

    2014-12-01

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

  15. 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

  16. DIFFERENCES IN LEAF GAS EXCHANGE AND LEAF CHARACTERISTICS BETWEEN TWO ALMOND CULTIVARS

    Directory of Open Access Journals (Sweden)

    George D. Nanos

    2013-12-01

    Full Text Available Leaf chlorophyll content, specific leaf weight (SLW, photosynthetic and transpiration rates, stomatal functioning, water use efficiency and quantum yield were assessed during the kernel filling period for two consecutive years in order to understand tissue-centered physiological profile differences between two commercial almond cultivars, ‘Ferragnès’ and ‘Texas’. Similar SLWs were observed on the studied cultivars; however, chlorophyll content, net photosynthetic and transpiration rates and stomatal functioning demonstrated statistically significant differences. In both cultivars, an overall decline in the examined parameters towards fruit maturation (i.e. end of the summer was recorded. ‘Ferragnès’ leaves were found to be more efficient in leaf photosynthesis related performance during kernel filling, when irrigated sufficiently, in comparison to ‘Texas’ leaves. Low average values of leaf conductance during summer in ‘Texas’ leaves revealed its potential for adaptation in cool climates and increased carbon assimilation therein for high kernel yield.

  17. 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

  18. 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

  19. Infrared remote sensing for canopy temperature in paddy field and relationship between leaf temperature and leaf color

    International Nuclear Information System (INIS)

    Wakiyama, Y.

    2002-01-01

    Infrared remote sensing is used for crop monitoring, for example evaluation of water stress, detection of infected crops and estimation of transpiration and photosynthetic rates. This study was conducted to show another application of remote sensing information. The relationship between rice leaf temperature and chlorophyll content in the leaf blade was investigated by using thermography during the ripening period. The canopy of a rice community fertilized by top dressing was cooler than that not fertilized in a 1999 field experiment. In an experiment using thermocouples to measure leaf temperature, a rice leaf with high chlorophyll content was also cooler than that with a low chlorophyll content. Transpiration resistance and transpiration rate were measured with a porometer. Transpiration rate was higher with increasing chlorophyll content in the leaf blade. Stomatal aperture is related to chlorophyll content in the leaf blade. High degree of stomatal aperture is caused by high chlorophyll content in the leaf blade. As degree of stomatal aperture increases, transpiration rate increases. Therefore the rice leaf got cooler with increasing chlorophyll content in leaf blade. Paddy rice communities with different chlorophyll contents were provided with fertilization of different nitrogen levels on basal and top dressing in a 2000 field experiment. Canopy temperature of the rice community with high chlorophyll content was 0.85°C cooler than that of the rice community with low chlorophyll content. Results of this study revealed that infrared remote sensing could detect difference in chlorophyll contents in rice communities and could be used in fertilizer management in paddy fields. (author)

  20. 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.

  1. 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

    Stomatal conductance (gs) and photosynthetic biochemistry, typically expressed by the temperature-adjusted maximum rates of carboxylation (V cmax) and electron transport (Jmax), are key traits in land ecosystem models. Contrary to the many approaches available for simulating gs responses, the biochemical parameters V cmax and Jmax are often treated as static traits in ecosystem models. However, observational evidence indicates that V cmax and Jmax respond to persistent changes in atmospheric CO2. Hence, ecosystem models may be improved by incorporating coordinated responses of photosynthetic biochemistry and gs to atmospheric CO2. Recently, Prentice et al. (2014) proposed an optimality framework (referred to as the Prentice framework from here on) to predict relationships between V cmax and gs based on Fick's law, Rubisco-limited photosynthesis and the carbon costs of transpiration and photosynthesis. Here we show that this framework is, in principle, suited to predict CO2-induced changes in the V cmax -gs relationships. The framework predicts an increase in the V cmax:gs-ratio with higher atmospheric CO2, whereby the slope of this relationship is determined by the carbon costs of transpiration and photosynthesis. For our empirical analyses we consider that the carbon cost of transpiration is positively related to the plant's Huber value (sapwood area/leaf area), while the carbon cost of photosynthesis is positively related to the maintenance cost of the photosynthetic proteins. We empirically tested the predicted effect of CO2 on the V cmax:gs-ratio in two genotypes of Solanum dulcamara (bittersweet) that were grown from seeds to maturity under 200, 400 and 800 ppm CO2 in walk-in growth chambers with tight control on light, temperature and humidity. Seeds of the two Solanum genotypes were obtained from two distinct natural populations; one adapted to well-drained sandy soil (the 'dry' genotype) and one adapted to poorly-drained clayey soil (the 'wet' genotype

  2. 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...

  3. 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.

  4. Variability in mesophyll conductance between barley genotypes, and effects on transpiration efficiency and carbon isotope discrimination.

    Science.gov (United States)

    Barbour, Margaret M; Warren, Charles R; Farquhar, Graham D; Forrester, Guy; Brown, Hamish

    2010-07-01

    Leaf internal, or mesophyll, conductance to CO(2) (g(m)) is a significant and variable limitation of photosynthesis that also affects leaf transpiration efficiency (TE). Genotypic variation in g(m) and the effect of g(m) on TE were assessed in six barley genotypes (four Hordeum vulgare and two H. bulbosum). Significant variation in g(m) was found between genotypes, and was correlated with photosynthetic rate. The genotype with the highest g(m) also had the highest TE and the lowest carbon isotope discrimination as recorded in leaf tissue (Delta(p)). These results suggest g(m) has unexplored potential to provide TE improvement within crop breeding programmes.

  5. 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.

  6. Biophysical control of leaf temperature

    Science.gov (United States)

    Dong, N.; Prentice, I. C.; Wright, I. J.

    2014-12-01

    In principle sunlit leaves can maintain their temperatures within a narrower range than ambient temperatures. This is an important and long-known (but now overlooked) prediction of energy balance theory. Net radiation at leaf surface in steady state (which is reached rapidly) must be equal to the combination of sensible and latent heat exchanges with surrounding air, the former being proportional to leaf-to-air temperature difference (ΔT), the latter to the transpiration rate. We present field measurements of ΔT which confirm the existence of a 'crossover temperature' in the 25-30˚C range for species in a tropical savanna and a tropical rainforest environment. This finding is consistent with a simple representation of transpiration as a function of net radiation and temperature (Priestley-Taylor relationship) assuming an entrainment factor (ω) somewhat greater than the canonical value of 0.26. The fact that leaves in tropical forests are typically cooler than surrounding air, often already by solar noon, is consistent with a recently published comparison of MODIS day-time land-surface temperatures with air temperatures. Theory further predicts a strong dependence of leaf size (which is inversely related to leaf boundary-layer conductance, and therefore to absolute magnitude of ΔT) on moisture availability. Theoretically, leaf size should be determined by either night-time constraints (risk of frost damage to active leaves) or day-time constraints (risk of heat stress damage),with the former likely to predominate - thereby restricting the occurrence of large leaves - at high latitudes. In low latitudes, daytime maximum leaf size is predicted to increase with temperature, provided that water is plentiful. If water is restricted, however, transpiration cannot proceed at the Priestley-Taylor rate, and it quickly becomes advantageous for plants to have small leaves, which do not heat up much above the temperature of their surroundings. The difference between leaf

  7. 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.

  8. 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.

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

    Science.gov (United States)

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

    2017-12-01

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

  10. 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.

  11. 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.

  12. 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.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    ) than the low group, accompanied by higher stomatal conductance (gs), transpiration rate (E) and evaporative cooling of the leaf (ΔT). The difference in PN between the groups was not caused by differences in PSII capacity or gs as the variation in Fv/Fm and intracellular CO2 (Ci) was non...

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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...

  19. Diurnal depression in leaf hydraulic conductance at ambient and elevated [CO2] and reveals anisohydric water management in field-grown soybean

    Science.gov (United States)

    Diurnal cycles of photosynthesis and water use in field-grown soybean (Glycine max) are tied to light intensity and vapor pressure deficit (VPD). At high mid-day VPD, transpiration rates can lead to a decline in leaf water potential ('leaf) if leaf hydraulic conductance (Kleaf) is insufficient to su...

  20. 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.

  1. 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

  2. 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

  3. 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)).

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

    Science.gov (United States)

    Burkhardt, Juergen; Hunsche, Mauricio

    2013-01-01

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

  5. ‘Breath figures’ on leaf surfaces – formation and effects of microscopic leaf wetness

    Directory of Open Access Journals (Sweden)

    Jürgen eBurkhardt

    2013-10-01

    Full Text Available ‘Microscopic leaf wetness’ means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 µm, microscopic leaf wetness it is about 2 orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the amount and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g. ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past.

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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

  12. 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...

  13. Tree differences in primary and secondary growth drive convergent scaling in leaf area to sapwood area across Europe

    NARCIS (Netherlands)

    Petit, Giai; Arx, von Georg; Kiorapostolou, Natasa; Lechthaler, Silvia; Prendin, Angela Luisa; Anfodillo, Tommaso; Caldeira, Maria C.; Cochard, Hervé; Copini, Paul; Crivellaro, Alan; Delzon, Sylvain; Gebauer, Roman; Gričar, Jožica; Grönholm, Leila; Hölttä, Teemu; Jyske, Tuula; Lavrič, Martina; Lintunen, Anna; Lobo-do-Vale, Raquel; Peltoniemi, Mikko; Peters, Richard L.; Robert, Elisabeth M.R.; Roig Juan, Sílvia; Senfeldr, Martin; Steppe, Kathy; Urban, Josef; Camp, Van Janne; Sterck, Frank

    2018-01-01

    Trees scale leaf (AL) and xylem (AX) areas to couple leaf transpiration and carbon gain with xylem water transport. Some species are known to acclimate in AL: AX balance in response to climate conditions, but whether trees of different species acclimate in AL: AX in similar ways over their entire

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. Abscisic acid and transpiration rate are involved in the response to boron toxicity in Arabidopsis plants.

    Science.gov (United States)

    Macho-Rivero, Miguel Ángel; Camacho-Cristóbal, Juan José; Herrera-Rodríguez, María Begoña; Müller, Maren; Munné-Bosch, Sergi; González-Fontes, Agustín

    2017-05-01

    Boron (B) is an essential microelement for vascular plant development, but its toxicity is a major problem affecting crop yields in arid and semi-arid areas of the world. In the literature, several genes involved in abscisic acid (ABA) signalling and responses are upregulated in Arabidopsis roots after treatment with excess B. It is known that the AtNCED3 gene, which encodes a crucial enzyme for ABA biosynthesis, plays a key role in the plant response to drought stress. In this study, root AtNCED3 expression and shoot ABA content were rapidly increased in wild-type plants upon B-toxicity treatment. The Arabidopsis ABA-deficient nced3-2 mutant had higher transpiration rate, stomatal conductance and accumulated more B in their shoots than wild-type plants, facts that were associated with the lower levels of ABA in this mutant. However, in wild-type plants, B toxicity caused a significant reduction in stomatal conductance, resulting in a decreased transpiration rate. This response could be a mechanism to limit the transport of excess B from the roots to the leaves under B toxicity. In agreement with the higher transpiration rate of the nced3-2 mutant, this genotype showed an increased leaf B concentration and damage upon exposure to 5 mM B. Under B toxicity, ABA application decreased B accumulation in wild-type and nced3-2 plants. In summary, this work shows that excess B applied to the roots leads to rapid changes in AtNCED3 expression and gas exchange parameters that would contribute to restrain the B entry into the leaves, this effect being mediated by ABA. © 2016 Scandinavian Plant Physiology Society.

  19. 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.

  20. Genotypic variation in transpiration efficiency due to differences in photosynthetic capacity among sugarcane-related clones.

    Science.gov (United States)

    Li, Chunjia; Jackson, Phillip; Lu, Xin; Xu, Chaohua; Cai, Qing; Basnayake, Jayapathi; Lakshmanan, Prakash; Ghannoum, Oula; Fan, Yuanhong

    2017-04-01

    Sugarcane, derived from the hybridization of Saccharum officinarum×Saccharum spontaneum, is a vegetative crop in which the final yield is highly driven by culm biomass production. Cane yield under irrigated or rain-fed conditions could be improved by developing genotypes with leaves that have high intrinsic transpiration efficiency, TEi (CO2 assimilation/stomatal conductance), provided this is not offset by negative impacts from reduced conductance and growth rates. This study was conducted to partition genotypic variation in TEi among a sample of diverse clones from the Chinese collection of sugarcane-related germplasm into that due to variation in stomatal conductance versus that due to variation in photosynthetic capacity. A secondary goal was to define protocols for optimized larger-scale screening of germplasm collections. Genotypic variation in TEi was attributed to significant variation in both stomatal and photosynthetic components. A number of genotypes were found to possess high TEi as a result of high photosynthetic capacity. This trait combination is expected to be of significant breeding value. It was determined that a small number of observations (16) is sufficient for efficiently screening TEi in larger populations of sugarcane genotypes The research methodology and results reported are encouraging in supporting a larger-scale screening and introgression of high transpiration efficiency in sugarcane breeding. However, further research is required to quantify narrow sense heritability as well as the leaf-to-field translational potential of genotypic variation in transpiration efficiency-related traits observed in this study. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  1. Relating Stomatal Conductance to Leaf Functional Traits.

    Science.gov (United States)

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

    2015-10-12

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

  2. 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.

  3. 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...

  4. 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...

  5. 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.

  6. 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.

  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. 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.

  9. A hairy-leaf gene, BLANKET LEAF, of wild Oryza nivara increases photosynthetic water use efficiency in rice.

    Science.gov (United States)

    Hamaoka, Norimitsu; Yasui, Hideshi; Yamagata, Yoshiyuki; Inoue, Yoko; Furuya, Naruto; Araki, Takuya; Ueno, Osamu; Yoshimura, Atsushi

    2017-12-01

    High water use efficiency is essential to water-saving cropping. Morphological traits that affect photosynthetic water use efficiency are not well known. We examined whether leaf hairiness improves photosynthetic water use efficiency in rice. A chromosome segment introgression line (IL-hairy) of wild Oryza nivara (Acc. IRGC105715) with the genetic background of Oryza sativa cultivar 'IR24' had high leaf pubescence (hair). The leaf hairs developed along small vascular bundles. Linkage analysis in BC 5 F 2 and F 3 populations showed that the trait was governed by a single gene, designated BLANKET LEAF (BKL), on chromosome 6. IL-hairy plants had a warmer leaf surface in sunlight, probably due to increased boundary layer resistance. They had a lower transpiration rate under moderate and high light intensities, resulting in higher photosynthetic water use efficiency. Introgression of BKL on chromosome 6 from O. nivara improved photosynthetic water use efficiency in the genetic background of IR24.

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

    Directory of Open Access Journals (Sweden)

    Sousa Elias Fernandes de

    2005-01-01

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

  11. 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

  12. Does homeostasis or disturbance of homeostasis in minimum leaf water potential explain the isohydric versus anisohydric behavior of Vitis vinifera L. cultivars?

    Science.gov (United States)

    Jean-Christophe Domec; Daniel M. Johnson

    2012-01-01

    Due to the diurnal and seasonal fluctuations in leaf-to-air vapor pressure deficit (D), one of the key regulatory roles played by stomata is to limit transpiration-induced leaf water deficit. Different types of plants are known to vary in the sensitivity of stomatal conductance (gs) to D with important consequences for their survival and growth. Plants that minimize...

  13. Diurnal depression in leaf hydraulic conductance at ambient and elevated [CO2] reveals anisohydric water management in field-grown soybean

    Science.gov (United States)

    Diurnal cycles of photosynthesis and water use in field-grown soybean (Glycine max) are tied to light intensity and vapor pressure deficit (VPD). At high mid-day VPD, transpiration rates can lead to a decline in leaf water potential if leaf hydraulic conductance is insufficient to supply water to in...

  14. 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.

  15. Leaf absorbance and photosynthesis

    Science.gov (United States)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  16. 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.

  17. The influence of clouds and diffuse radiation on ecosystem-atmosphere CO2 and CO18O exhanges

    Energy Technology Data Exchange (ETDEWEB)

    Still, C.J.; Riley, W.J.; Biraud, S.C.; Noone, D.C.; Buenning, N.H.; Randerson, J.T.; Torn, M.S.; Welker, J.; White, J.W.C.; Vachon, R.; Farquhar, G.D.; Berry, J.A.

    2009-05-01

    This study evaluates the potential impact of clouds on ecosystem CO{sub 2} and CO{sub 2} isotope fluxes ('isofluxes') in two contrasting ecosystems (a broadleaf deciduous forest and a C{sub 4} grassland), in a region for which cloud cover, meteorological, and isotope data are available for driving the isotope-enabled land surface model, ISOLSM. Our model results indicate a large impact of clouds on ecosystem CO{sub 2} fluxes and isofluxes. Despite lower irradiance on partly cloudy and cloudy days, predicted forest canopy photosynthesis was substantially higher than on clear, sunny days, and the highest carbon uptake was achieved on the cloudiest day. This effect was driven by a large increase in light-limited shade leaf photosynthesis following an increase in the diffuse fraction of irradiance. Photosynthetic isofluxes, by contrast, were largest on partly cloudy days, as leaf water isotopic composition was only slightly depleted and photosynthesis was enhanced, as compared to adjacent clear sky days. On the cloudiest day, the forest exhibited intermediate isofluxes: although photosynthesis was highest on this day, leaf-to-atmosphere isofluxes were reduced from a feedback of transpiration on canopy relative humidity and leaf water. Photosynthesis and isofluxes were both reduced in the C{sub 4} grass canopy with increasing cloud cover and diffuse fraction as a result of near-constant light limitation of photosynthesis. These results suggest that some of the unexplained variation in global mean {delta}{sup 18}O of CO{sub 2} may be driven by large-scale changes in clouds and aerosols and their impacts on diffuse radiation, photosynthesis, and relative humidity.

  18. Combined preharvest and postharvest treatments affect rapid leaf wilting in Bouvardia cut flowers

    NARCIS (Netherlands)

    Schouten, Rob E.; Dien, van Luka; Shahin, Arwa; Heimovaara, Sjoukje; Meeteren, van Uulke; Verdonk, Julian C.

    2018-01-01

    Bouvardia is an ornamental shrub, commercially cultivated as flowering stem. Occasionally, negative water balance, which leads to rapid leaf wilting, ends vase life immediately. This work studies the effect of preharvest and postharvest conditions on vase life, water uptake and transpiration.

  19. Remote sensing of leaf, canopy and vegetation water contents for satellite climate data records

    Science.gov (United States)

    Foliar water content is a dynamic quantity depending on water losses from transpiration and water uptake from the soil. Absorption of shortwave radiation by water is determined by various frequency overtones of fundamental bending and stretching molecular transitions. Leaf water potential and rela...

  20. Coordination of leaf and stem water transport properties in tropical forest trees

    Science.gov (United States)

    Frederick C. Meinzer; David R. Woodruff; Jean-Christophe Domec; Guillermo Goldstein; Paula I. Campanello; Genoveva M. Gatti; Randol Villalobos-Vega

    2008-01-01

    Stomatal regulation of transpiration constrains leaf water potential (ψ l) within species-specific ranges that presumably avoid excessive tension and embolism in the stem xylem upstream. However, the hydraulic resistance of leaves can be highly variable over short time scales, uncoupling tension in the xylem of leaves from that in the...

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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

  7. The transpiration cooled first wall and blanket concept

    International Nuclear Information System (INIS)

    Barleon, Leopold; Wong, Clement

    2002-01-01

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

  8. 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

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

    African Journals Online (AJOL)

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

  10. 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.

  11. Do Aphids Alter Leaf Surface Temperature Patterns During Early Infestation?

    Directory of Open Access Journals (Sweden)

    Thomas Cahon

    2018-03-01

    Full Text Available Arthropods at the surface of plants live in particular microclimatic conditions that can differ from atmospheric conditions. The temperature of plant leaves can deviate from air temperature, and leaf temperature influences the eco-physiology of small insects. The activity of insects feeding on leaf tissues, may, however, induce changes in leaf surface temperatures, but this effect was only rarely demonstrated. Using thermography analysis of leaf surfaces under controlled environmental conditions, we quantified the impact of presence of apple green aphids on the temperature distribution of apple leaves during early infestation. Aphids induced a slight change in leaf surface temperature patterns after only three days of infestation, mostly due to the effect of aphids on the maximal temperature that can be found at the leaf surface. Aphids may induce stomatal closure, leading to a lower transpiration rate. This effect was local since aphids modified the configuration of the temperature distribution over leaf surfaces. Aphids were positioned at temperatures near the maximal leaf surface temperatures, thus potentially experiencing the thermal changes. The feedback effect of feeding activity by insects on their host plant can be important and should be quantified to better predict the response of phytophagous insects to environmental changes.

  12. 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.

  13. [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.

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

    Directory of Open Access Journals (Sweden)

    Hipólito Medrano

    2015-06-01

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

  15. Genotype-dependent variation in the transpiration efficiency of plants and photosynthetic activity of flag leaves in spring barley under varied nutrition.

    Science.gov (United States)

    Krzemińska, Anetta; Górny, Andrzej G

    2003-01-01

    In the study, spring barley genotypes of various origin and breeding history were found to show a broad genetic variation in the vegetative and generative measures of the whole-plant transpiration efficiency (TE), photosynthesis (A) and transpiration (E) rates of flag leaves, leaf efficiency of gas exchange (A/E) and stress tolerance (T) when grown till maturity in soil-pots under high and reduced NPK supplies. Broad-sense heritabilities for the characteristics ranged from 0.61 to 0.87. Significant genotype-nutrition interactions were noticed, constituting 19-23% of the total variance in TE measures. The results suggest that at least some 'exotic' accessions from Ethiopia, Syria, Morocco and/or Tibet may serve as attractive genetic sources of novel variations in TE, T and A for the breeding of barleys of improved adaptation to less favourable fertilisation.

  16. 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

  17. 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...

  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. 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.

  20. 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

  1. Maximum transpiration, reference evapotranspiration and leaf area relationships for some mango cultivars

    OpenAIRE

    OLIVEIRA, Greice Ximena Santos; COELHO FILHO, Maurício Antonio; PEREIRA, Francisco Adriano de Carvalho; COELHO, Eugênio Ferreira; PAZ, Vital Pedro da Silva; CASTRO NETO, Manoel Teixeira de

    2009-01-01

    Nas condições edafoclimáticas de Cruz da Almas - BA, na Embrapa Mandioca e Fruticultura Tropical, foi realizado um estudo no qual se relacionou a transpiração máxima (Litros m-2 folha/dia -1) de quatro variedades de mangueira (Tommy Atkins, Palmer, Haden e Van Dyke, com áreas foliares totais de 14; 8; 33 e 12 m², respectivamente) com a evapotranspiração de referência (ETo). A transpiração das plantas (L dia-1) foi estimada por meio de sensores que realizam o balanço de calor no caule (modelos...

  2. 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.

  3. 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.

  4. Stomatal conductance, mesophyll conductance, and trans piration efficiency in relation to leaf anatomy in rice and wheat genotypes under drought

    NARCIS (Netherlands)

    Ouyang, Wenjing; Struik, Paul C.; Yin, Xinyou; Yang, Jianchang

    2017-01-01

    Increasing leaf transpiration efficiency (TE) may provide leads for growing rice like dryland cereals such as wheat (Triticum aestivum). To explore avenues for improving TE in rice, variations in stomatal conductance (g s) and mesophyll conductance (g m) and their anatomical determinants were

  5. 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

  6. Apparent over-investment in leaf venation relaxes leaf morphological constraints on photosynthesis in arid habitats

    Science.gov (United States)

    de Boer, Hugo; Drake, Paul; Veneklaas, Erik

    2017-04-01

    The close relationship between leaf water status and stomatal conductance implies that the hydraulic architecture of leaves poses an important constraint on transpiration, specifically in arid environments with high evaporative demands. However, it remains uncertain how morphological, hydraulic and photosynthetic traits are coordinated to achieve optimal leaf functioning in arid environments. Critical is that leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy≈1. Although this theory is supported by observations on many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis we assembled leaf hydraulic, morphological and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent over-investment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf lifespan, high hydraulic and thermal capacitances, and high potential rates of leaf

  7. 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.

  8. 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.

  9. 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.

  10. Relationship of transpiration and evapotranspiration to solar radiation and spectral reflectance in soybean [Glycine max] canopies: A simple method for remote sensing of canopy transpiration

    International Nuclear Information System (INIS)

    Choi, E.N.; Inoue, Y.

    2004-01-01

    Abstract The study investigated diurnal and seasonal dynamics of evapotranspiration (ET) and transpiration (Tr) in a soybean canopy, as well as the relationships among ET, Tr, solar radiation and remotely sensed spectral reflectance. The eddy covariance method (ECM) and stem heat balance method (SHBM) were used for independent measurement of ET and Tr, respectively. Micrometeorological, soil, and spectral reflectance data were acquired for the entire growing season. The instantaneous values of canopy-Tr estimated by SHBM and ET by ECM were well synchronized with each other, and both were strongly affected by the solar radiation. The daily values canopy-Tr increased rapidly with increasing leaf area index (LAI), and got closer to the ET even at a low value of LAI such as 1.5-2. The daily values of ET were moderately correlated with global solar radiation (Rs), and more closely with the potential evapotranspiration (ETp), estimated by the 'radiation method.' This fact supported the effectiveness of the simple radiation method in estimation of evapotranspiration. The ratio of Tr/ET as well as the ratio of ground heat flux (G) to Rs (G/Rs) was closely related to LAI, and LAI was a key variable in determining the energy partitioning to soil and vegetation. It was clearly shown that a remotely sensed vegetation index such as SAVI (soil adjusted vegetation index) was effective for estimating LAI, and further useful for directly estimating energy partitioning to soil and vegetation. The G and Tr/ET were both well estimated by the vegetation index. It was concluded that the combination of a simple radiation method with remotely sensed information can provide useful information on energy partitioning and Tr/ET in vegetation canopies

  11. Metric diffusion along foliations

    CERN Document Server

    Walczak, Szymon M

    2017-01-01

    Up-to-date research in metric diffusion along compact foliations is presented in this book. Beginning with fundamentals from the optimal transportation theory and the theory of foliations; this book moves on to cover Wasserstein distance, Kantorovich Duality Theorem, and the metrization of the weak topology by the Wasserstein distance. Metric diffusion is defined, the topology of the metric space is studied and the limits of diffused metrics along compact foliations are discussed. Essentials on foliations, holonomy, heat diffusion, and compact foliations are detailed and vital technical lemmas are proved to aide understanding. Graduate students and researchers in geometry, topology and dynamics of foliations and laminations will find this supplement useful as it presents facts about the metric diffusion along non-compact foliation and provides a full description of the limit for metrics diffused along foliation with at least one compact leaf on the two dimensions.

  12. 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

  13. 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.

  14. 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

  15. 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...

  16. Green Leaf Volatile Emissions during High Temperature and Drought Stress in a Central Amazon Rainforest.

    Science.gov (United States)

    Jardine, Kolby J; Chambers, Jeffrey Q; Holm, Jennifer; Jardine, Angela B; Fontes, Clarissa G; Zorzanelli, Raquel F; Meyers, Kimberly T; de Souza, Vinicius Fernadez; Garcia, Sabrina; Gimenez, Bruno O; Piva, Luani R de O; Higuchi, Niro; Artaxo, Paulo; Martin, Scot; Manzi, Antônio O

    2015-09-15

    Prolonged drought stress combined with high leaf temperatures can induce programmed leaf senescence involving lipid peroxidation, and the loss of net carbon assimilation during early stages of tree mortality. Periodic droughts are known to induce widespread tree mortality in the Amazon rainforest, but little is known about the role of lipid peroxidation during drought-induced leaf senescence. In this study, we present observations of green leaf volatile (GLV) emissions during membrane peroxidation processes associated with the combined effects of high leaf temperatures and drought-induced leaf senescence from individual detached leaves and a rainforest ecosystem in the central Amazon. Temperature-dependent leaf emissions of volatile terpenoids were observed during the morning, and together with transpiration and net photosynthesis, showed a post-midday depression. This post-midday depression was associated with a stimulation of C₅ and C₆ GLV emissions, which continued to increase throughout the late afternoon in a temperature-independent fashion. During the 2010 drought in the Amazon Basin, which resulted in widespread tree mortality, green leaf volatile emissions (C₆ GLVs) were observed to build up within the forest canopy atmosphere, likely associated with high leaf temperatures and enhanced drought-induced leaf senescence processes. The results suggest that observations of GLVs in the tropical boundary layer could be used as a chemical sensor of reduced ecosystem productivity associated with drought stress.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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...

  2. 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...

  3. 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

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

    Directory of Open Access Journals (Sweden)

    Córcoles J.I.

    2015-06-01

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

  5. Smaller stomata require less severe leaf drying to close: A case study in Rosa hydrida

    DEFF Research Database (Denmark)

    Gebraegziabher, Habtamu Giday; Kjær, Katrine Heinsvig; Fanourakis, D.

    2013-01-01

    Stomata formed at high relative air humidity (RH) close less as leaf dries; an effect that varies depending on the genotype. We here quantified the contribution of each stomatal response characteristic to the higher water loss of high RH-grown plants, and assessed the relationship between response...... characteristics and intraspecific variation in stomatal size. Stomatal size (length multiplied by width), density and responsiveness to desiccation, as well as pore dimensions were analyzed in ten rose cultivars grown at moderate (60%) or high (85%) RH. Leaf morphological components and transpiration at growth...... conditions were also assessed. High growth RH resulted in thinner (11%) leaves with larger area. A strong positive genetic correlation of daytime and nighttime transpiration at either RH was observed. Stomatal size determined pore area (r = 0.7) and varied by a factor of two, as a result of proportional...

  6. 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)

  7. [Seasonal differences in the leaf hydraulic conductance of mature Acacia mangium in response to its leaf water use and photosynthesis].

    Science.gov (United States)

    Zhao, Ping; Sun, Gu-Chou; Ni, Guang-Yan; Zeng, Xiao-Ping

    2013-01-01

    In this study, measurements were made on the leaf water potential (psi1), stomatal conductance (g(s)), transpiration rate, leaf area index, and sapwood area of mature Acacia mangium, aimed to understand the relationships of the leaf hydraulic conductance (K1) with the leaf water use and photosynthetic characteristics of the A. mangium in wet season (May) and dry season (November). The ratio of sapwood area to leaf area (A(sp)/A(cl)) of the larger trees with an average height of 20 m and a diameter at breast height (DBH) of 0.26 m was 8.5% higher than that of the smaller trees with an average height of 14.5 m and a DBH of 0.19 m, suggesting that the larger trees had a higher water flux in their leaf xylem, which facilitated the water use of canopy leaf. The analysis on the vulnerability curve of the xylem showed that when the K1 decreased by 50%, the psi1 in wet season and dry season was -1.41 and -1.55 MPa, respectively, and the vulnerability of the xylem cavitation was higher in dry season than in wet season. The K1 peak value in wet season and dry season was 5.5 and 4.5 mmol x m(-2) x s(-1) x MPa(-1), and the maximum transpiration rate (T(r max)) was 3.6 and 1.8 mmol x m(-2) x s(-1), respectively. Both the K1 and T(r max), were obviously higher in wet season than in dry season. Within a day, the K1 and T(r), fluctuated many times, reflecting the reciprocated cycle of the xylem cavitation and refilling. The leaf stomatal closure occurred when the K1 declined over 50% or the psi1 reached -1.6 MPa. The g(s) would be maintained at a high level till the K1 declined over 50%. The correlation between the hydraulic conductance and photosynthetic rate was more significant in dry season than in wet season. The loss of leaf hydraulic conductance induced by seasonal change could be the causes of the decrease of T(r) and CO2 gas exchange.

  8. 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...

  9. [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.

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

    Science.gov (United States)

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

    2015-10-01

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

  11. Herbivory mitigation through increased water-use efficiency in a leaf-mining moth-apple tree relationship.

    Science.gov (United States)

    Pincebourde, Sylvain; Frak, Ela; Sinoquet, Hervé; Regnard, Jean Luc; Casas, Jérôme

    2006-12-01

    Herbivory alters plant gas exchange but the effects depend on the type of leaf damage. In contrast to ectophagous insects, leaf miners, by living inside the leaf tissues, do not affect the integrity of the leaf surface. Thus, the effect of leaf miners on CO2 uptake and water-use efficiency by leaves remains unclear. We explored the impacts of the leaf-mining moth Phyllonorycter blancardella (Lepidoptera: Gracillariidae) on light responses of the apple leaf gas exchanges to determine the balance between the negative effects of reduced photosynthesis and potential positive impacts of increased water-use efficiency (WUE). Gas exchange in intact and mined leaf tissues was measured using an infrared gas analyser. The maximal assimilation rate was slightly reduced but the light response of net photosynthesis was not affected in mined leaf tissues. The transpiration rate was far more affected than the assimilation rate in the mine integument as a result of stomatal closure from moderate to high irradiance level. The WUE was about 200% higher in the mined leaf tissues than in intact leaf portions. Our results illustrate a novel mechanism by which plants might minimize losses from herbivore attacks; via trade-offs between the negative impacts on photosynthesis and the positive effects of increased WUE.

  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. 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

  14. Branch age and light conditions determine leaf-area-specific conductivity in current shoots of Scots pine.

    Science.gov (United States)

    Grönlund, Leila; Hölttä, Teemu; Mäkelä, Annikki

    2016-08-01

    Shoot size and other shoot properties more or less follow the availability of light, but there is also evidence that the topological position in a tree crown has an influence on shoot development. Whether the hydraulic properties of new shoots are more regulated by the light or the position affects the shoot acclimation to changing light conditions and thereby to changing evaporative demand. We investigated the leaf-area-specific conductivity (and its components sapwood-specific conductivity and Huber value) of the current-year shoots of Scots pine (Pinus sylvestris L.) in relation to light environment and topological position in three different tree classes. The light environment was quantified in terms of simulated transpiration and the topological position was quantified by parent branch age. Sample shoot measurements included length, basal and tip diameter, hydraulic conductivity of the shoot, tracheid area and density, and specific leaf area. In our results, the leaf-area-specific conductivity of new shoots declined with parent branch age and increased with simulated transpiration rate of the shoot. The relation to transpiration demand seemed more decisive, since it gave higher R(2) values than branch age and explained the differences between the tree classes. The trend of leaf-area-specific conductivity with simulated transpiration was closely related to Huber value, whereas the trend of leaf-area-specific conductivity with parent branch age was related to a similar trend in sapwood-specific conductivity. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  15. 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

  16. 35-44 Growth, Photosynthetic Efficiency, Rate of Transpiration ...

    African Journals Online (AJOL)

    0.533 mmhoscm-1 electrical conductivity and a pH of 8.6. 2.2. Variety ... After good establishment, the main stem of five randomly ... The interaction effect of stage and rate of PBZ application on plant height and culm length, panicle and flag leaf length ..... where it decreases the rate of cell division and elongation, ultimately ...

  17. 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.

  18. Mycorrhizal Stimulation of Leaf Gas Exchange in Relation to Root Colonization, Shoot Size, Leaf Phosphorus and Nitrogen: A Quantitative Analysis of the Literature Using Meta-Regression.

    Science.gov (United States)

    Augé, Robert M; Toler, Heather D; Saxton, Arnold M

    2016-01-01

    Arbuscular mycorrhizal (AM) symbiosis often stimulates gas exchange rates of the host plant. This may relate to mycorrhizal effects on host nutrition and growth rate, or the influence may occur independently of these. Using meta-regression, we tested the strength of the relationship between AM-induced increases in gas exchange, and AM size and leaf mineral effects across the literature. With only a few exceptions, AM stimulation of carbon exchange rate (CER), stomatal conductance (g s), and transpiration rate (E) has been significantly associated with mycorrhizal stimulation of shoot dry weight, leaf phosphorus, leaf nitrogen:phosphorus ratio, and percent root colonization. The sizeable mycorrhizal stimulation of CER, by 49% over all studies, has been about twice as large as the mycorrhizal stimulation of g s and E (28 and 26%, respectively). CER has been over twice as sensitive as g s and four times as sensitive as E to mycorrhizal colonization rates. The AM-induced stimulation of CER increased by 19% with each AM-induced doubling of shoot size; the AM effect was about half as large for g s and E. The ratio of leaf N to leaf P has been more closely associated with mycorrhizal influence on leaf gas exchange than leaf P alone. The mycorrhizal influence on CER has declined markedly over the 35 years of published investigations.

  19. Mycorrhizal stimulation of leaf gas exchange in relation to root colonization, shoot size, leaf phosphorus and nitrogen: a quantitative analysis of the literature using meta-regression

    Directory of Open Access Journals (Sweden)

    Robert M. Augé

    2016-07-01

    Full Text Available Arbuscular mycorrhizal (AM symbiosis often stimulates gas exchange rates of the host plant. This may relate to mycorrhizal effects on host nutrition and growth rate, or the influence may occur independently of these. Using meta-regression, we tested the strength of the relationship between AM-induced increases in gas exchange, and AM size and leaf mineral effects across the literature. With only a few exceptions, AM stimulation of carbon exchange rate (CER, stomatal conductance (gs and transpiration rate (E has been significantly associated with mycorrhizal stimulation of shoot dry weight, leaf phosphorus, leaf nitrogen: phosphorus ratio and percent root colonization. The sizeable mycorrhizal stimulation of CER, by 49% over all studies, has been about twice as large as the mycorrhizal stimulation of gs and E (28% and 26%, respectively. Carbon exchange rate has been over twice as sensitive as gs and four times as sensitive as E to mycorrhizal colonization rates. The AM-induced stimulation of CER increased by 19% with each AM-induced doubling of shoot size; the AM effect was about half as large for gs and E. The ratio of leaf N to leaf P has been more closely associated with mycorrhizal influence on leaf gas exchange than leaf P alone. The mycorrhizal influence on CER has declined markedly over the 35 years of published investigations.

  20. 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.

  1. 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

  2. Measurement of leaf hydraulic conductance and stomatal conductance and their responses to irradiance and dehydration using the Evaporative Flux Method (EFM).

    Science.gov (United States)

    Sack, Lawren; Scoffoni, Christine

    2012-12-31

    Water is a key resource, and the plant water transport system sets limits on maximum growth and drought tolerance. When plants open their stomata to achieve a high stomatal conductance (gs) to capture CO2 for photosynthesis, water is lost by transpiration(1,2). Water evaporating from the airspaces is replaced from cell walls, in turn drawing water from the xylem of leaf veins, in turn drawing from xylem in the stems and roots. As water is pulled through the system, it experiences hydraulic resistance, creating tension throughout the system and a low leaf water potential (Ψ(leaf)). The leaf itself is a critical bottleneck in the whole plant system, accounting for on average 30% of the plant hydraulic resistance(3). Leaf hydraulic conductance (K(leaf) = 1/ leaf hydraulic resistance) is the ratio of the water flow rate to the water potential gradient across the leaf, and summarizes the behavior of a complex system: water moves through the petiole and through several orders of veins, exits into the bundle sheath and passes through or around mesophyll cells before evaporating into the airspace and being transpired from the stomata. K(leaf) is of strong interest as an important physiological trait to compare species, quantifying the effectiveness of the leaf structure and physiology for water transport, and a key variable to investigate for its relationship to variation in structure (e.g., in leaf venation architecture) and its impacts on photosynthetic gas exchange. Further, K(leaf) responds strongly to the internal and external leaf environment(3). K(leaf) can increase dramatically with irradiance apparently due to changes in the expression and activation of aquaporins, the proteins involved in water transport through membranes(4), and K(leaf) declines strongly during drought, due to cavitation and/or collapse of xylem conduits, and/or loss of permeability in the extra-xylem tissues due to mesophyll and bundle sheath cell shrinkage or aquaporin deactivation(5

  3. Leaf morphophysiology of a Neotropical mistletoe is shaped by seasonal patterns of host leaf phenology.

    Science.gov (United States)

    Scalon, Marina Corrêa; Rossatto, Davi Rodrigo; Domingos, Fabricius Maia Chaves Bicalho; Franco, Augusto Cesar

    2016-04-01

    Several mistletoe species are able to grow and reproduce on both deciduous and evergreen hosts, suggesting a degree of plasticity in their ability to cope with differences in intrinsic host functions. The aim of this study was to investigate the influence of host phenology on mistletoe water relations and leaf gas exchange. Mistletoe Passovia ovata parasitizing evergreen (Miconia albicans) hosts and P. ovata parasitizing deciduous (Byrsonima verbascifolia) hosts were sampled in a Neotropical savanna. Photosynthetic parameters, diurnal cycles of stomatal conductance, pre-dawn and midday leaf water potential, and stomatal anatomical traits were measured during the peak of the dry and wet seasons, respectively. P. ovata showed distinct water-use strategies that were dependent on host phenology. For P. ovata parasitizing the deciduous host, water use efficiency (WUE; ratio of photosynthetic rate to transpirational water loss) was 2-fold lower in the dry season than in the wet season; in contrast, WUE was maintained at the same level during the wet and dry seasons in P. ovata parasitizing the evergreen host. Generally, mistletoe and host diurnal cycles of stomatal conductance were linked, although there were clear differences in leaf water potential, with mistletoe showing anisohydric behaviour and the host showing isohydric behaviour. Compared to mistletoes attached to evergreen hosts, those parasitizing deciduous hosts had a 1.4-fold lower stomatal density and 1.2-fold wider stomata on both leaf surfaces, suggesting that the latter suffered less intense drought stress. This is the first study to show morphophysiological differences in the same mistletoe species parasitizing hosts of different phenological groups. Our results provide evidence that phenotypical plasticity (anatomical and physiological) might be essential to favour the use of a greater range of hosts.

  4. Spatial trends in leaf size of Amazonian rainforest trees

    Science.gov (United States)

    Malhado, A. C. M.; Malhi, Y.; Whittaker, R. J.; Ladle, R. J.; Ter Steege, H.; Phillips, O. L.; Butt, N.; Aragão, L. E. O. C.; Quesada, C. A.; Araujo-Murakami, A.; Arroyo, L.; Peacock, J.; Lopez-Gonzalez, G.; Baker, T. R.; Anderson, L. O.; Almeida, S.; Higuchi, N.; Killeen, T. J.; Monteagudo, A.; Neill, D.; Pitman, N.; Prieto, A.; Salomão, R. P.; Vásquez-Martínez, R.; Laurance, W. F.

    2009-08-01

    Leaf size influences many aspects of tree function such as rates of transpiration and photosynthesis and, consequently, often varies in a predictable way in response to environmental gradients. The recent development of pan-Amazonian databases based on permanent botanical plots has now made it possible to assess trends in leaf size across environmental gradients in Amazonia. Previous plot-based studies have shown that the community structure of Amazonian trees breaks down into at least two major ecological gradients corresponding with variations in soil fertility (decreasing from southwest to northeast) and length of the dry season (increasing from northwest to south and east). Here we describe the geographic distribution of leaf size categories based on 121 plots distributed across eight South American countries. We find that the Amazon forest is predominantly populated by tree species and individuals in the mesophyll size class (20.25-182.25 cm2). The geographic distribution of species and individuals with large leaves (>20.25 cm2) is complex but is generally characterized by a higher proportion of such trees in the northwest of the region. Spatially corrected regressions reveal weak correlations between the proportion of large-leaved species and metrics of water availability. We also find a significant negative relationship between leaf size and wood density.

  5. Physiological, vascular and nanomechanical assessment of hybrid poplar leaf traits in micropropagated plants and plants propagated from root cuttings: A contribution to breeding programs.

    Science.gov (United States)

    Ďurkovič, Jaroslav; Husárová, Hana; Javoříková, Lucia; Čaňová, Ingrid; Šuleková, Miriama; Kardošová, Monika; Lukáčik, Ivan; Mamoňová, Miroslava; Lagaňa, Rastislav

    2017-09-01

    Micropropagated plants experience significant stress from rapid water loss when they are transferred from an in vitro culture to either greenhouse or field conditions. This is caused both by inefficient stomatal control of transpiration and the change to a higher light intensity and lower humidity. Understanding the physiological, vascular and biomechanical processes that allow micropropagated plants to modify their phenotype in response to environmental conditions can help to improve both field performance and plant survival. To identify changes between the hybrid poplar [Populus tremula × (Populus × canescens)] plants propagated from in vitro tissue culture and those from root cuttings, we assessed leaf performance for any differences in leaf growth, photosynthetic and vascular traits, and also nanomechanical properties of the tracheary element cell walls. The micropropagated plants showed significantly higher values for leaf area, leaf length, leaf width and leaf dry mass. The greater leaf area and leaf size dimensions resulted from the higher transpiration rate recorded for this stock type. Also, the micropropagated plants reached higher values for chlorophyll a fluorescence parameters and for the nanomechanical dissipation energy of tracheary element cell walls which may indicate a higher damping capacity within the primary xylem tissue under abiotic stress conditions. The performance of the plants propagated from root cuttings was superior for instantaneous water-use efficiency which signifies a higher acclimation capacity to stressful conditions during a severe drought particularly for this stock type. Similarities were found among the majority of the examined leaf traits for both vegetative plant origins including leaf mass per area, stomatal conductance, net photosynthetic rate, hydraulic axial conductivity, indicators of leaf midrib vascular architecture, as well as for the majority of cell wall nanomechanical traits. This research revealed that

  6. 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)

  7. 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.

  8. 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...

  9. Distribution of leaf characteristics in relation to orientation within the canopy of woody species

    Science.gov (United States)

    Escudero, Alfonso; Fernández, José; Cordero, Angel; Mediavilla, Sonia

    2013-04-01

    Over the last few decades considerable effort has been devoted to research of leaf adaptations to environmental conditions. Many studies have reported strong differences in leaf mass per unit area (LMA) within a single tree depending on the photosynthetic photon flux density (PPFD) incident on different locations in the crown. There are fewer studies, however, of the effects of differences in the timing of light incidence during the day on different crown orientations. Leaves from isolated trees of Quercus suber and Quercus ilex in a cold Mediterranean climate were sampled to analyze differences in LMA and other leaf traits among different crown orientations. Gas-exchange rates, leaf water potentials, leaf temperatures and PPFD incident on leaf surfaces in different crown orientations were also measured throughout one entire summer day for each species. Mean daily PPFD values were similar for the leaves from the eastern and western sides of the canopy. On the western side, PPFD reached maximum values during the afternoon. Maximum leaf temperatures were approximately 10-20% higher on the west side, whereas minimum leaf water potentials were between 10 and 24% higher on the east side. Maximum transpiration rates were approximately 22% greater on the west, because of the greater leaf-to-air vapor pressure deficits (LAVPD). Mean individual leaf area was around 10% larger on the east than on the west side of the trees. In contrast, there were no significant differences in LMA between east and west sides of the crown. Contrary to our expectations, more severe water stress on the west side did not result in increases in LMA, although it was associated with lower individual leaf area. We conclude that increases in LMA measured by other authors along gradients of water stress would be due to differences in light intensity between dry and humid sites.

  10. 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

  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. 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.

  13. 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.

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

    Science.gov (United States)

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

    2016-12-01

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

  16. 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

  17. Seagrass leaf element content

    NARCIS (Netherlands)

    Vonk, J.A.; Smulders, Fee O.H.; Christianen, Marjolijn J.A.; Govers, Laura L.

    2017-01-01

    Knowledge on the role of seagrass leaf elements and in particular micronutrients and their ranges is limited. We present a global database, consisting of 1126 unique leaf values for ten elements, obtained from literature and unpublished data, spanning 25 different seagrass species from 28 countries.

  18. Inter-annual variation in the response of leaf-out onset to soil moisture increase in a teak plantation in northern Thailand.

    Science.gov (United States)

    Yoshifuji, Natsuko; Igarashi, Yasunori; Tanaka, Nobuaki; Tanaka, Katsunori; Sato, Takanori; Tantasirin, Chatchai; Suzuki, Masakazu

    2014-11-01

    To understand the impact of inter-annual climate change on vegetation-atmosphere mass and energy exchanges, it has become necessary to explore changes in leaf-out onset in response to climatic fluctuations. We examined the response of leaf-out and transpiration onset dates to soil moisture in a teak plantation in northern Thailand based on a 12-year leaf area index and sap flow measurements. The date of leaf-out and transpiration onset varied between years by up to 40 days, and depended on the initial date when the relative extractable water in a soil layer of 0-0.6 m (Θ) was greater than 0.2 being consistent with our previous results. Our new finding is that the delay in leaf-out and transpiration onset relative to the initial date when Θ > 0.2 increases linearly as the initial date on which Θ > 0.2 becomes earlier. The delay spans about 20 days in years when Θ > 0.2 occurs in March (the late dry season)-much earlier than usual because of heavy pre-monsoon rainfalls-while there is little delay in years when Θ > 0.2 occurs in May. This delay indicates the influence of additional factors on leaf-out onset, which controls the delay in the response of leaf-out to soil moisture increase. The results increased our knowledge about the pattern and extent of the changes in leaf phenology that occur in response to the inter-annual climate variation in tropical regions, where, in particular, such research is needed.

  19. Dependence of leaf surface potential response of a plant (Ficus Elastica) to light irradiation on room temperature; Shokubutsu (gomunoki) hamen den`i no hikari shosha oto no shitsuon izonsei

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, H; Kenmoku, Y; Sakakibara, T [Toyohashi University of Technology, Aichi (Japan); Nakagawa, S [Maizuru National College of Technology, Kyoto (Japan); Kawamoto, T [Shizuoka University, Shizuoka (Japan)

    1997-11-25

    In order to clarify plant body potential information, study was made on a leaf surface potential response to light irradiation. The leaf surface potential change, total transpiration and transpiration rate of Ficus Elastica were measured using light irradiation period and room temperature as parameters. The leaf surface potential change shows a positive peak after the start of light irradiation, while a negative peak after its end. Arrival time to both peaks is constant regardless of the light irradiation period, while decrease with an increase in room temperature. Although the total transpiration increases with room temperature, this tendency disappears with an increase in light irradiation period. The transpiration rate shows its peak after the start of light irradiation. Arrival time to the peak is saturated with the light irradiation period of 60min, while decreases with an increase in room temperature. These results suggest that opening of stomata becomes active with an increase in room temperature, and the peak of the leaf surface potential after the start of light irradiation relates to the opening. 3 refs., 11 figs.

  20. Modeling whole-tree carbon assimilation rate using observed transpiration rates and needle sugar carbon isotope ratios.

    Science.gov (United States)

    Hu, Jia; Moore, David J P; Riveros-Iregui, Diego A; Burns, Sean P; Monson, Russell K

    2010-03-01

    *Understanding controls over plant-atmosphere CO(2) exchange is important for quantifying carbon budgets across a range of spatial and temporal scales. In this study, we used a simple approach to estimate whole-tree CO(2) assimilation rate (A(Tree)) in a subalpine forest ecosystem. *We analysed the carbon isotope ratio (delta(13)C) of extracted needle sugars and combined it with the daytime leaf-to-air vapor pressure deficit to estimate tree water-use efficiency (WUE). The estimated WUE was then combined with observations of tree transpiration rate (E) using sap flow techniques to estimate A(Tree). Estimates of A(Tree) for the three dominant tree species in the forest were combined with species distribution and tree size to estimate and gross primary productivity (GPP) using an ecosystem process model. *A sensitivity analysis showed that estimates of A(Tree) were more sensitive to dynamics in E than delta(13)C. At the ecosystem scale, the abundance of lodgepole pine trees influenced seasonal dynamics in GPP considerably more than Engelmann spruce and subalpine fir because of its greater sensitivity of E to seasonal climate variation. *The results provide the framework for a nondestructive method for estimating whole-tree carbon assimilation rate and ecosystem GPP over daily-to weekly time scales.

  1. 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.

  2. Generality of leaf trait relationships: A test across six biomes

    Energy Technology Data Exchange (ETDEWEB)

    Reich, P.B. [Univ. of Minnesota, Saint Paul, MN (United States). Dept. of Forest Resources; Ellsworth, D.S. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science; Walters, M.B. [Michigan State Univ., East Lansing, MI (United States). Dept. of Forestry; Vose, J.M. [Forest Service, Otto, NC (United States). Coweeta Hydrological Lab.; Gresham, C. [Clemson Univ., Georgetown, SC (United States). Baruch Forest Inst.; Volin, J.C. [Florida Atlantic Univ., Davie, FL (United States). Div. of Science; Bowman, W.D. [Inst. of Arctic and Alpine Research, Boulder, CO (United States). Mountain Research Station]|[Univ. of Colorado, Boulder, CO (United States). Dept. of Evolutionary, Population, and Organismic Biology

    1999-09-01

    Convergence in interspecific leaf trait relationships across diverse taxonomic groups and biomes would have important evolutionary and ecological implications. Such convergence has been hypothesized to result from trade-offs that limit the combination of plant traits for any species. Here the authors address this issue by testing for biome differences in the slope and intercept of interspecific relationships among leaf traits: longevity, net photosynthetic capacity (A{sub max}), leaf diffusive conductance (G{sub S}), specific leaf area (SLA), and nitrogen (N) status, for more than 100 species in six distinct biomes of the Americas. The six biomes were: alpine tundra-subalpine forest ecotone, cold temperate forest-prairie ecotone, montane cool temperate forest, desert shrubland, subtropical forest, and tropical rain forest. Despite large differences in climate and evolutionary history, in all biomes mass-based leaf N (N{sub mass}), SLA, G{sub S}, and A{sub max} were positively related to one another and decreased with increasing leaf life span. The relationships between pairs of leaf traits exhibited similar slopes among biomes, suggesting a predictable set of scaling relationships among key leaf morphological, chemical, and metabolic traits that are replicated globally among terrestrial ecosystems regardless of biome or vegetation type. However, the intercept (i.e., the overall elevation of regression lines) of relationships between pairs of leaf traits usually differed among biomes. With increasing aridity across sites, species had greater A{sub max} for a given level of G{sub S} and lower SLA for any given leaf life span. Using principal components analysis, most variation among species was explained by an axis related to mass-based leaf traits (A{sub max}, N, and SLA) while a second axis reflected climate, G{sub S}, and other area-based leaf traits.

  3. 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.

  4. 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.

  5. PROTEOMIC PROFILE REVEALS THE DIVERSITY AND COMPLEXITY OF LEAF PROTEINS IN SPINACH (BETA VULGARIS VAR. ALL GREEN

    Directory of Open Access Journals (Sweden)

    Sudip Ghosh

    2016-06-01

    Full Text Available Leaf is a source organ that serves dual function in photosynthesis and transpiration. As a primary interface between plant and ecosystem, it performs a range of biological processes from carbon assimilation and metabolite partitioning to plant productivity. Basic features of the leaf functionality are conserved in angiosperms exhibiting common and unique characteristics. Spinach has been the model crop for studying leaf function, primarily photosynthesis. It is a reservoir of several hundreds of primary and secondary biomolecules. To better understand the molecular basis for photochemical reaction and metabolic partitioning, we developed leaf proteome of Indian spinach (Beta vulgaris var. all green. LC-ESI-MS/MS analysis identified 639 proteins exhibiting discrete molecular features and functions, including photosynthesis, transpiration, gaseous exchange, transport, redox status, cell defense, and floral induction besides the presence of proteins with unknown function. This represents the first comprehensive foliage proteome of green leafy vegetable. Together, this work provides important insights into the molecular networks underlying spinach leaf biological processes.

  6. A 3-D functional-structural grapevine model that couples the dynamics of water transport with leaf gas exchange.

    Science.gov (United States)

    Zhu, Junqi; Dai, Zhanwu; Vivin, Philippe; Gambetta, Gregory A; Henke, Michael; Peccoux, Anthony; Ollat, Nathalie; Delrot, Serge

    2017-12-23

    Predicting both plant water status and leaf gas exchange under various environmental conditions is essential for anticipating the effects of climate change on plant growth and productivity. This study developed a functional-structural grapevine model which combines a mechanistic understanding of stomatal function and photosynthesis at the leaf level (i.e. extended Farqhuhar-von Caemmerer-Berry model) and the dynamics of water transport from soil to individual leaves (i.e. Tardieu-Davies model). The model included novel features that account for the effects of xylem embolism (fPLC) on leaf hydraulic conductance and residual stomatal conductance (g0), variable root and leaf hydraulic conductance, and the microclimate of individual organs. The model was calibrated with detailed datasets of leaf photosynthesis, leaf water potential, xylem sap abscisic acid (ABA) concentration and hourly whole-plant transpiration observed within a soil drying period, and validated with independent datasets of whole-plant transpiration under both well-watered and water-stressed conditions. The model well captured the effects of radiation, temperature, CO2 and vapour pressure deficit on leaf photosynthesis, transpiration, stomatal conductance and leaf water potential, and correctly reproduced the diurnal pattern and decline of water flux within the soil drying period. In silico analyses revealed that decreases in g0 with increasing fPLC were essential to avoid unrealistic drops in leaf water potential under severe water stress. Additionally, by varying the hydraulic conductance along the pathway (e.g. root and leaves) and changing the sensitivity of stomatal conductance to ABA and leaf water potential, the model can produce different water use behaviours (i.e. iso- and anisohydric). The robust performance of this model allows for modelling climate effects from individual plants to fields, and for modelling plants with complex, non-homogenous canopies. In addition, the model provides a

  7. 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

  8. 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

  9. Effects of CO[sub 2] concentration on photosynthesis, transpiration and production of greenhouse fruit vegetable crops

    Energy Technology Data Exchange (ETDEWEB)

    Nederhoff, E.M.

    1994-10-25

    The effect of the CO[sub 2] concentration of the greenhouse air (C) in the range 200 to 1100 [mu]mol mol[sup -1] was investigated in tomato (Lycopersicon esculentum Mill.), cucumber (Cucumis sativus L.), sweet pepper (Capsicum annuum L.) and eggplant (Solanum melongena L.), grown in greenhouses. The effect of C on canopy net photosynthetic CO[sub 2] assimilation rate (or photosynthesis, P) was expressed by a set of regression equations, relating P to PAR, C and LAI. A rule of thumb ('CO[sub 2]-rule') was derived, approximating the relative increase of P caused by additional CO[sub 2] at a certain C. This CO[sub 2]-rule is: X = (1000/C)[sup 2] * 1.5 (X in % per 100 [mu]mol[sup -1], and C in [mu]mol mol[sup -1]). Two models for canopy photosynthesis were examined by comparing them with the experimental photosynthesis data. No 'midday depression' in P was observed. The effects of C on leaf conductance (g) and on rate of crop transpiration (E) were investigated. An increase of 100 I[mu]mol mol[sup -1] ' in C reduced g by about 3-4% in sweet pepper, tomato and cucumber and by about 11% in eggplant. The effect of C on E was analyzed by combining the regression equation for g with the Penman-Monteith equation for E. C had only a relatively small effect on E, owing to thermal and hydrological feedback effects. The decoupling of g and E was quantified. No time-dependent variation or 'midday depression' in E was observed, and no significant effect of C on average leaf temperature was established. In five experiments, the effect of C on growth and production and on specific features were analyzed; fruit production (dry weight) was most affected by C in sweet pepper; fresh weight fruit production per unit CO[sub 2] was highest in cucumber; fruit quality was not influenced by C. High C promoted the 'short leaves syndrome' in tomato and 'leaf tip chlorosis' in eggplant, probably related to calcium and boron translocation

  10. 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.

  11. 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.

  12. [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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. The heterogeneity and spatial patterning of structure and physiology across the leaf surface in giant leaves of Alocasia macrorrhiza.

    Directory of Open Access Journals (Sweden)

    Shuai Li

    Full Text Available Leaf physiology determines the carbon acquisition of the whole plant, but there can be considerable variation in physiology and carbon acquisition within individual leaves. Alocasia macrorrhiza (L. Schott is an herbaceous species that can develop very large leaves of up to 1 m in length. However, little is known about the hydraulic and photosynthetic design of such giant leaves. Based on previous studies of smaller leaves, and on the greater surface area for trait variation in large leaves, we hypothesized that A. macrorrhiza leaves would exhibit significant heterogeneity in structure and function. We found evidence of reduced hydraulic supply and demand in the outer leaf regions; leaf mass per area, chlorophyll concentration, and guard cell length decreased, as did stomatal conductance, net photosynthetic rate and quantum efficiency of photosystem II. This heterogeneity in physiology was opposite to that expected from a thinner boundary layer at the leaf edge, which would have led to greater rates of gas exchange. Leaf temperature was 8.8°C higher in the outer than in the central region in the afternoon, consistent with reduced stomatal conductance and transpiration caused by a hydraulic limitation to the outer lamina. The reduced stomatal conductance in the outer regions would explain the observed homogeneous distribution of leaf water potential across the leaf surface. These findings indicate substantial heterogeneity in gas exchange across the leaf surface in large leaves, greater than that reported for smaller-leafed species, though the observed structural differences across the lamina were within the range reported for smaller-leafed species. Future work will determine whether the challenge of transporting water to the outer regions can limit leaf size for plants experiencing drought, and whether the heterogeneity of function across the leaf surface represents a particular disadvantage for large simple leaves that might explain their

  20. Geometric leaf placement strategies

    International Nuclear Information System (INIS)

    Fenwick, J D; Temple, S W P; Clements, R W; Lawrence, G P; Mayles, H M O; Mayles, W P M

    2004-01-01

    Geometric leaf placement strategies for multileaf collimators (MLCs) typically involve the expansion of the beam's-eye-view contour of a target by a uniform MLC margin, followed by movement of the leaves until some point on each leaf end touches the expanded contour. Film-based dose-distribution measurements have been made to determine appropriate MLC margins-characterized through an index d 90 -for multileaves set using one particular strategy to straight lines lying at various angles to the direction of leaf travel. Simple trigonometric relationships exist between different geometric leaf placement strategies and are used to generalize the results of the film work into d 90 values for several different strategies. Measured d 90 values vary both with angle and leaf placement strategy. A model has been derived that explains and describes quite well the observed variations of d 90 with angle. The d 90 angular variations of the strategies studied differ substantially, and geometric and dosimetric reasoning suggests that the best strategy is the one with the least angular variation. Using this criterion, the best straightforwardly implementable strategy studied is a 'touch circle' approach for which semicircles are imagined to be inscribed within leaf ends, the leaves being moved until the semicircles just touch the expanded target outline

  1. Anti-transpirant activity in xylem sap from flooded tomato (Lycopersicon esculentum Mill.) plants is not due to pH-mediated redistributions of root- or shoot-sourced ABA.

    Science.gov (United States)

    Else, Mark A; Taylor, June M; Atkinson, Christopher J

    2006-01-01

    In flooded soils, the rapid effects of decreasing oxygen availability on root metabolic activity are likely to generate many potential chemical signals that may impact on stomatal apertures. Detached leaf transpiration tests showed that filtered xylem sap, collected at realistic flow rates from plants flooded for 2 h and 4 h, contained one or more factors that reduced stomatal apertures. The closure could not be attributed to increased root output of the glucose ester of abscisic acid (ABA-GE), since concentrations and deliveries of ABA conjugates were unaffected by soil flooding. Although xylem sap collected from the shoot base of detopped flooded plants became more alkaline within 2 h of flooding, this rapid pH change of 0.5 units did not alter partitioning of root-sourced ABA sufficiently to prompt a transient increase in xylem ABA delivery. More shoot-sourced ABA was detected in the xylem when excised petiole sections were perfused with pH 7 buffer, compared with pH 6 buffer. Sap collected from the fifth oldest leaf of "intact" well-drained plants and plants flooded for 3 h was more alkaline, by approximately 0.4 pH units, than sap collected from the shoot base. Accordingly, xylem [ABA] was increased 2-fold in sap collected from the fifth oldest petiole compared with the shoot base of flooded plants. However, water loss from transpiring, detached leaves was not reduced when the pH of the feeding solution containing 3-h-flooded [ABA] was increased from 6.7 to 7.1 Thus, the extent of the pH-mediated, shoot-sourced ABA redistribution was not sufficient to raise xylem [ABA] to physiologically active levels. Using a detached epidermis bioassay, significant non-ABA anti-transpirant activity was also detected in xylem sap collected at intervals during the first 24 h of soil flooding.

  2. Soybean leaf hydraulic conductance does not acclimate to growth at elevated [CO2] or temperature in growth chambers or in the field.

    Science.gov (United States)

    Locke, Anna M; Sack, Lawren; Bernacchi, Carl J; Ort, Donald R

    2013-09-01

    Leaf hydraulic properties are strongly linked with transpiration and photosynthesis in many species. However, it is not known if gas exchange and hydraulics will have co-ordinated responses to climate change. The objective of this study was to investigate the responses of leaf hydraulic conductance (Kleaf) in Glycine max (soybean) to growth at elevated [CO2] and increased temperature compared with the responses of leaf gas exchange and leaf water status. Two controlled-environment growth chamber experiments were conducted with soybean to measure Kleaf, stomatal conductance (gs) and photosynthesis (A) during growth at elevated [CO2] and temperature relative to ambient levels. These results were validated with field experiments on soybean grown under free-air elevated [CO2] (FACE) and canopy warming. In chamber studies, Kleaf did not acclimate to growth at elevated [CO2], even though stomatal conductance decreased and photosynthesis increased. Growth at elevated temperature also did not affect Kleaf, although gs and A showed significant but inconsistent decreases. The lack of response of Kleaf to growth at increased [CO2] and temperature in chamber-grown plants was confirmed with field-grown soybean at a FACE facility. Leaf hydraulic and leaf gas exchange responses to these two climate change factors were not strongly linked in soybean, although gs responded to [CO2] and increased temperature as previously reported. This differential behaviour could lead to an imbalance between hydraulic supply and transpiration demand under extreme environmental conditions likely to become more common as global climate continues to change.

  3. Antimicrobial olive leaf gelatin films for enhancing the quality of cold smoked salmon

    Science.gov (United States)

    Olive leaf products were evaluated as antimicrobial/antioxidant ingredients in edible films for smoked fish preservation. Olive leaf powder (OLP) and its water/ethanol extract (OLE) were tested against Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella enterica using agar diffusion test...

  4. 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...

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

    Science.gov (United States)

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

    2016-05-01

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

  6. 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. 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

  8. Tree differences in primary and secondary growth drive convergent scaling in leaf area to sapwood area across Europe.

    Science.gov (United States)

    Petit, Giai; von Arx, Georg; Kiorapostolou, Natasa; Lechthaler, Silvia; Prendin, Angela Luisa; Anfodillo, Tommaso; Caldeira, Maria C; Cochard, Hervé; Copini, Paul; Crivellaro, Alan; Delzon, Sylvain; Gebauer, Roman; Gričar, Jožica; Grönholm, Leila; Hölttä, Teemu; Jyske, Tuula; Lavrič, Martina; Lintunen, Anna; Lobo-do-Vale, Raquel; Peltoniemi, Mikko; Peters, Richard L; Robert, Elisabeth M R; Roig Juan, Sílvia; Senfeldr, Martin; Steppe, Kathy; Urban, Josef; Van Camp, Janne; Sterck, Frank

    2018-06-01

    Trees scale leaf (A L ) and xylem (A X ) areas to couple leaf transpiration and carbon gain with xylem water transport. Some species are known to acclimate in A L  : A X balance in response to climate conditions, but whether trees of different species acclimate in A L  : A X in similar ways over their entire (continental) distributions is unknown. We analyzed the species and climate effects on the scaling of A L vs A X in branches of conifers (Pinus sylvestris, Picea abies) and broadleaved (Betula pendula, Populus tremula) sampled across a continental wide transect in Europe. Along the branch axis, A L and A X change in equal proportion (isometric scaling: b ˜ 1) as for trees. Branches of similar length converged in the scaling of A L vs A X with an exponent of b = 0.58 across European climates irrespective of species. Branches of slow-growing trees from Northern and Southern regions preferentially allocated into new leaf rather than xylem area, with older xylem rings contributing to maintaining total xylem conductivity. In conclusion, trees in contrasting climates adjust their functional balance between water transport and leaf transpiration by maintaining biomass allocation to leaves, and adjusting their growth rate and xylem production to maintain xylem conductance. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

  9. Poiseuille, thermal transpiration and Couette flows of a rarefied gas between plane parallel walls with nonuniform surface properties in the transverse direction and their reciprocity relations

    Science.gov (United States)

    Doi, Toshiyuki

    2018-04-01

    Slow flows of a rarefied gas between two plane parallel walls with nonuniform surface properties are studied based on kinetic theory. It is assumed that one wall is a diffuse reflection boundary and the other wall is a Maxwell-type boundary whose accommodation coefficient varies periodically in the direction perpendicular to the flow. The time-independent Poiseuille, thermal transpiration and Couette flows are considered. The flow behavior is numerically studied based on the linearized Bhatnagar-Gross-Krook-Welander model of the Boltzmann equation. The flow field, the mass and heat flow rates in the gas, and the tangential force acting on the wall surface are studied over a wide range of the gas rarefaction degree and the parameters characterizing the distribution of the accommodation coefficient. The locally convex velocity distribution is observed in Couette flow of a highly rarefied gas, similarly to Poiseuille flow and thermal transpiration. The reciprocity relations are numerically confirmed over a wide range of the flow parameters.

  10. 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...

  11. In vitro antibacterial activity of Anogeissus leiocarpus leaf extracts on ...

    African Journals Online (AJOL)

    In vitro antibacterial activity of aqueous and ethanol extracts of the leaf of Anogeissus leiocarpus was tested on some bacteria associated with diarrhea which included Escherichia coli,Salmonella typhi,Salmonella typhimurium, Klebsiella aerogens and Yersinia enterocolitica using agar well diffusion method. There was ...

  12. Use of the transpiration method to study polonium evaporation from liquid lead-bismuth eutectic at high temperature

    International Nuclear Information System (INIS)

    Prieto, Borja Gonzalez; Lim, Jun; Rosseel, Kris; Bosch, Joris van den; Aerts, Alexander; Martens, Johan; Rizzi, Matthias; Neuhausen, Joerg

    2014-01-01

    Qualitative and quantitative understanding of Po volatilization under different conditions is of key importance for safety assessments of lead-bismuth eutectic (LBE) based nuclear reactors, spallation targets and accelerator driven systems. In this work we explore the possibilities of the transpiration method in combination with simple models to study the equilibrium and kinetics of Po evaporation from highly diluted solutions in lead-bismuth eutectic between 600 and 1000 C in Ar/5% H 2 and Ar. On the basis of evaporation experiments at various carrier gas flow rates, we identified the conditions of vapor saturation allowing the determination of equilibrium constants. From the limiting behavior at high flow rates, values for the maximal evaporation rate of Po from LBE were estimated. Measurements of evaporation as a function of time were consistent with the assumption that polonium dissolved in LBE obeys Henry's law. A theoretical analysis furthermore suggested that diffusion of polonium in LBE was not a rate limiting factor for evaporation under vapor saturation conditions. Newly determined values for the Henry constant of Po in LBE between 600 and 1000 C were consistent with previously derived correlations.

  13. Acclimation to high CO2 in maize is related to water status and dependent on leaf rank.

    Science.gov (United States)

    Prins, Anneke; Mukubi, Josephine Muchwesi; Pellny, Till K; Verrier, Paul J; Beyene, Getu; Lopes, Marta Silva; Emami, Kaveh; Treumann, Achim; Lelarge-Trouverie, Caroline; Noctor, Graham; Kunert, Karl J; Kerchev, Pavel; Foyer, Christine H

    2011-02-01

    The responses of C(3) plants to rising atmospheric CO(2) levels are considered to be largely dependent on effects exerted through altered photosynthesis. In contrast, the nature of the responses of C(4) plants to high CO(2) remains controversial because of the absence of CO(2) -dependent effects on photosynthesis. In this study, the effects of atmospheric CO(2) availability on the transcriptome, proteome and metabolome profiles of two ranks of source leaves in maize (Zea mays L.) were studied in plants grown under ambient CO(2) conditions (350 +/- 20 µL L(-1) CO(2) ) or with CO(2) enrichment (700 +/- 20 µL L(-1) CO(2) ). Growth at high CO(2) had no effect on photosynthesis, photorespiration, leaf C/N ratios or anthocyanin contents. However, leaf transpiration rates, carbohydrate metabolism and protein carbonyl accumulation were altered at high CO(2) in a leaf-rank specific manner. Although no significant CO(2) -dependent changes in the leaf transcriptome were observed, qPCR analysis revealed that the abundance of transcripts encoding a Bowman-Birk protease inhibitor and a serpin were changed by the growth CO(2) level in a leaf rank specific manner. Moreover, CO(2) -dependent changes in the leaf proteome were most evident in the oldest source leaves. Small changes in water status may be responsible for the observed responses to high CO(2,) particularly in the older leaf ranks. © 2010 Blackwell Publishing Ltd.

  14. 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...

  15. 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...

  16. 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...

  17. 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.

  18. 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...

  19. 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.

  20. 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

  1. 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...

  2. Unveiling stomata 24/7: can we use carbonyl sulfide (COS) and oxygen isotopes (18O) to constrain estimates of nocturnal transpiration across different evolutionary plant forms?

    Science.gov (United States)

    Gimeno, Teresa E.; Ogee, Jerome; Bosc, Alexander; Genty, Bernard; Wohl, Steven; Wingate, Lisa

    2015-04-01

    Numerous studies have reported a continued flux of water through plants at night, suggesting that stomata are not fully closed. Growing evidence indicates that this nocturnal flux of transpiration might constitute an important fraction of total ecosystem water use in certain environments. However, because evaporative demand is usually low at night, nocturnal transpiration fluxes are generally an order of magnitude lower than rates measured during the day and perilously close to the measurement error of traditional gas-exchange porometers. Thus estimating rates of stomatal conductance in the dark (gnight) precisely poses a significant methodological challenge. As a result, we lack accurate field estimates of gnight and how it responds to different atmospheric drivers, indicating the need for a different measurement approach. In this presentation we propose a novel method to obtain detectable and robust estimates of gnight. We will demonstrate using mechanistic theory how independent tracers including the oxygen isotope composition of CO2 (δ18O) and carbonyl sulfide (COS) can be combined to obtain robust estimates of gnight. This is because COS and CO18O exchange within leaves are controlled by the light insensitive enzyme carbonic anhydrase. Thus, if plant stomata are open in the dark we will continue to observe COS and CO18O exchange. Using our theoretical model we will demonstrate that the exchange of these tracers can now be measured using advances in laser spectrometry techniques at a precision high enough to determine robust estimates of gnight. We will also present our novel experimental approach designed to measure simultaneously the exchange of CO18O and COS alongside the conventional technique that relies on measuring the total water flux from leaves in the dark. Using our theoretical approach we will additionally explore the feasibility of our proposed experimental design to detect variations in gnight during drought stress and across a variety of plant

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

    Science.gov (United States)

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

    2018-01-23

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

  4. Climate influences the leaf area/sapwood area ratio in Scots pine.

    Science.gov (United States)

    Mencuccini, M; Grace, J

    1995-01-01

    We tested the hypothesis that the leaf area/sapwood area ratio in Scots pine (Pinus sylvestris L.) is influenced by site differences in water vapor pressure deficit of the air (D). Two stands of the same provenance were selected, one in western Scotland and one in eastern England, so that effects resulting from age, genetic variability, density and fertility were minimized. Compared with the Scots pine trees at the cooler and wetter site in Scotland, the trees at the warmer and drier site in England produced less leaf area per unit of conducting sapwood area both at a stem height of 1.3 m and at the base of the live crown, whereas stem permeability was similar at both sites. Also, trees at the drier site had less leaf area per unit branch cross-sectional area at the branch base than trees at the wetter site. For each site, the average values for leaf area, sapwood area and permeability were used, together with values of transpiration rates at different D, to calculate average stem water potential gradients. Changes in the leaf area/sapwood area ratio acted to maintain a similar water potential gradient in the stems of trees at both sites despite climatic differences between the sites.

  5. 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

  6. 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)

  7. Antimony (SbIII) reduces growth, declines photosynthesis, and modifies leaf tissue anatomy in sunflower (Helianthus annuus L.).

    Science.gov (United States)

    Vaculík, Marek; Mrázová, Anna; Lux, Alexander

    2015-12-01

    The role of antimony (Sb)--a non-essential trace metalloid--in physiological processes running in crops is still poorly understood. Present paper describes the effect of Sb tartrate (SbIII) on growth, Sb uptake, photosynthesis, photosynthetic pigments, and leaf tissue organization in young sunflower plants grown in hydroponics. We found that growth of below- and aboveground part was reduced with increasing concentration of Sb in the medium. Although Sb was mostly taken up by sunflower roots and only small part (1-2%) was translocated to the shoots, decline in photosynthesis, transpiration, and decreased content of photosynthetic pigments were observed. This indicates that despite relatively low mobility of Sb in root-shoot system, Sb in shoot noticeably modifies physiological status and reduced plant growth. Additionally, leaf anatomical changes indicated that Sb reduced the size of intercellular spaces and made leaf tissue more compact.

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

    Science.gov (United States)

    Schrader, Julian; Pillar, Giso; Kreft, Holger

    2017-11-01

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

  9. Curso diário e sazonal das trocas gasosas e do potencial hídrico foliar em aceroleiras Daily and seasonal course of gas exchange and leaf water potential in acerola plants

    Directory of Open Access Journals (Sweden)

    REJANE JUREMA MANSUR CUSTÓDIO NOGUEIRA

    2000-07-01

    Full Text Available Este trabalho objetivou avaliar o curso diário e sazonal das trocas gasosas, da temperatura foliar e do potencial hídrico da acerola (Malpighia emarginata D.C., no campo. O experimento realizou-se no município de Paudalho, PE. Os valores da transpiração e do potencial da água foram, de modo geral, mais elevados no início da manhã e no final da tarde; os da resistência difusiva e temperatura foliar foram menores no início da manhã e no final da tarde. Houve uma limitação das trocas gasosas com o ambiente, em decorrência da redução da transpiração nas horas mais quentes do dia, sendo mais acentuada na estação seca e na matriz UFRPE 7. Os valores mínimos do potencial ocorreram na época seca, variando de -3,4 MPa (UFRPE 7 a -4,3 MPa (UFRPE 8, enquanto os valores máximos da resistência variaram de 16,30 s cm-1 (UFRPE 7 a 22,10 s cm-1 (UFRPE 8 na mesma estação. O potencial hídrico e a resistência difusiva mostraram forte correlação com o déficit de pressão de vapor. A maior capacidade fotossintética foi verificada em folhas maduras da matriz UFRPE 8. Os mecanismos fisiológicos apresentados pelas plantas demonstram que elas podem resistir a períodos de estresse hídrico quando estes se manifestam. A matriz UFRPE 8 é mais adaptada a períodos de estiagem do que a UFRPE 7.The daily and seasonal course of the gas exchanges, leaf temperature and water potential of Barbados cherry (Malpighia emarginata D.C. were evaluated under field conditions. The experiment was carried out in Paudalho, Pernambuco State, Brazil. Measurements of photosynthetic capacity in the wet season were also made. Changes in daily and seasonal behavior of gas exchange, water potential, and leaf temperature were observed. The transpiration and water potential measurements were higher at the beginning of the morning and at the end of the afternoon, while those for diffusive resistance and leaf temperature were lower at these same periods of the day

  10. Arbuscular Mycorrhizal Fungus Species Dependency Governs Better Plant Physiological Characteristics and Leaf Quality of Mulberry (Morus alba L.) Seedlings.

    Science.gov (United States)

    Shi, Song-Mei; Chen, Ke; Gao, Yuan; Liu, Bei; Yang, Xiao-Hong; Huang, Xian-Zhi; Liu, Gui-Xi; Zhu, Li-Quan; He, Xin-Hua

    2016-01-01

    Understanding the synergic interactions between arbuscular mycorrhizal fungi (AMF) and its host mulberry (Morus alba L.), an important perennial multipurpose plant, has theoretical and practical significance in mulberry plantation, silkworm cultivation, and relevant textile industry. In a greenhouse study, we compared functional distinctions of three genetically different AMF species (Acaulospora scrobiculata, Funneliformis mosseae, and Rhizophagus intraradices) on physiological and growth characteristics as well as leaf quality of 6-month-old mulberry seedlings. Results showed that mulberry was AMF-species dependent, and AMF colonization significantly increased shoot height and taproot length, stem base and taproot diameter, leaf and fibrous root numbers, and shoot and root biomass production. Meanwhile, leaf chlorophyll a or b and carotenoid concentrations, net photosynthetic rate, transpiration rate and stomatal conductance were generally significantly greater, while intercellular CO2 concentration was significantly lower in AMF-inoculated seedlings than in non-AMF-inoculated counterparts. These trends were also generally true for leaf moisture, total nitrogen, all essential amino acids, histidine, proline, soluble protein, sugar, and fatty acid as they were significantly increased under mycorrhization. Among these three tested AMFs, significantly greater effects of AMF on above-mentioned mulberry physiological and growth characteristics ranked as F. mosseae > A. scrobiculata > R. intraradices, whilst on mulberry leaf quality (e.g., nutraceutical values) for better silkworm growth as F. mosseae ≈A. scrobiculata > R. intraradices. In conclusion, our results showed that greater mulberry biomass production, and nutritional quality varied with AMF species or was AMF-species dependent. Such improvements were mainly attributed to AMF-induced positive alterations of mulberry leaf photosynthetic pigments, net photosynthetic rate, transpiration rate, and N

  11. Scaling up stomatal conductance from leaf to canopy using a dual-leaf model for estimating crop evapotranspiration.

    Directory of Open Access Journals (Sweden)

    Risheng Ding

    Full Text Available The dual-source Shuttleworth-Wallace model has been widely used to estimate and partition crop evapotranspiration (λET. Canopy stomatal conductance (Gsc, an essential parameter of the model, is often calculated by scaling up leaf stomatal conductance, considering the canopy as one single leaf in a so-called "big-leaf" model. However, Gsc can be overestimated or underestimated depending on leaf area index level in the big-leaf model, due to a non-linear stomatal response to light. A dual-leaf model, scaling up Gsc from leaf to canopy, was developed in this study. The non-linear stomata-light relationship was incorporated by dividing the canopy into sunlit and shaded fractions and calculating each fraction separately according to absorbed irradiances. The model includes: (1 the absorbed irradiance, determined by separately integrating the sunlit and shaded leaves with consideration of both beam and diffuse radiation; (2 leaf area for the sunlit and shaded fractions; and (3 a leaf conductance model that accounts for the response of stomata to PAR, vapor pressure deficit and available soil water. In contrast to the significant errors of Gsc in the big-leaf model, the predicted Gsc using the dual-leaf model had a high degree of data-model agreement; the slope of the linear regression between daytime predictions and measurements was 1.01 (R2 = 0.98, with RMSE of 0.6120 mm s-1 for four clear-sky days in different growth stages. The estimates of half-hourly λET using the dual-source dual-leaf model (DSDL agreed well with measurements and the error was within 5% during two growing seasons of maize with differing hydrometeorological and management strategies. Moreover, the estimates of soil evaporation using the DSDL model closely matched actual measurements. Our results indicate that the DSDL model can produce more accurate estimation of Gsc and λET, compared to the big-leaf model, and thus is an effective alternative approach for estimating and

  12. 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

  13. Antimicrobial activity of medicinal plant leaf extracts against pathogenic bacteria

    Directory of Open Access Journals (Sweden)

    Atikya Farjana

    2014-09-01

    Full Text Available Objective: To determine antibacterial activity of water, oil and methanol extracts of guava (Psidium guajava, green tea (Camellia sinensis, neem (Azadirachta indica and marigold (Calendula officinalis against different species of bacteria, Pseudomonas spp., Vibrio cholerae, Vibrio parahaemolyticus (V. parahaemolyticus, Klebsiella spp., Escherichia coli, Salmonella spp. and Staphylococcus aureus (S. aureus. Methods: Antibacterial activity of plant extracts was measured by agar well diffusion method. Results: Boiled water extracts of guava leaf showed the largest zone of inhibition (22 mm against V. parahaemolyticus. Water extracts of green tea leaf at boiling and room temperature showed 17.5 mm and 19 mm zone of inhibitions against V. parahaemolyticus and S. aureus, respectively. Boiled water extract of neem leaf showed moderate zone of inhibition against Escherichia coli (10 mm and Klebsiella spp. (11 mm. Water and oil extracts of marigold leaf at both boiling and room temperature did not show any zone of inhibition against any of the tested microorganisms. Methanol extracts of both guava and green tea leaves showed same zone of inhibition against Pseudomonus spp. (18 mm. Methanol extract of neem leaf showed antibacterial acitivity against Klebsiella spp. (16 mm and Vibrio cholerae (14 mm and that of marigold leaf showed antimicrobial activity against S. aureus (18 mm and Klebsiella spp. (12 mm. Conclusions: The results from the study suggest that the leaves of guava, green tea, neem and marigold show anibacterial activity against different bacterial species. They could be used as alternatives to common antimicrobial agents for treatment of bacterial infections.

  14. Diffuse radiation increases global ecosystem-level water-use efficiency

    Science.gov (United States)

    Moffat, A. M.; Reichstein, M.; Cescatti, A.; Knohl, A.; Zaehle, S.

    2012-12-01

    Current environmental changes lead not only to rising atmospheric CO2 levels and air temperature but also to changes in air pollution and thus the light quality of the solar radiation reaching the land-surface. While rising CO2 levels are thought to enhance photosynthesis and closure of stomata, thus leading to relative water savings, the effect of diffuse radiation on transpiration by plants is less clear. It has been speculated that the stimulation of photosynthesis by increased levels of diffuse light may be counteracted by higher transpiration and consequently water depletion and drought stress. Ultimately, in water co-limited systems, the overall effect of diffuse radiation will depend on the sensitivity of canopy transpiration versus photosynthesis to diffuse light, i.e. whether water-use efficiency changes with relative levels of diffuse light. Our study shows that water-use efficiency increases significantly with higher fractions of diffuse light. It uses the ecosystem-atmosphere gas-exchange observations obtained with the eddy covariance method at 29 flux tower sites. In contrast to previous global studies, the analysis is based directly on measurements of diffuse radiation. Its effect on water-use efficiency was derived by analyzing the multivariate response of carbon and water fluxes to radiation and air humidity using a purely empirical approach based on artificial neural networks. We infer that per unit change of diffuse fraction the water-use efficiency increases up to 40% depending on diffuse fraction levels and ecosystem type. Hence, in regions with increasing diffuse radiation positive effects on primary production are expected even under conditions where water is co-limiting productivity.

  15. 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

  16. Conservative diffusions

    International Nuclear Information System (INIS)

    Carlen, E.A.

    1984-01-01

    In Nelson's stochastic mechanics, quantum phenomena are described in terms of diffusions instead of wave functions. These diffusions are formally given by stochastic differential equations with extremely singular coefficients. Using PDE methods, we prove the existence of solutions. This reult provides a rigorous basis for stochastic mechanics. (orig.)

  17. 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

  18. 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

  19. 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.

  20. Effects of stomata clustering on leaf gas exchange.

    Science.gov (United States)

    Lehmann, Peter; Or, Dani

    2015-09-01

    A general theoretical framework for quantifying the stomatal clustering effects on leaf gaseous diffusive conductance was developed and tested. The theory accounts for stomatal spacing and interactions among 'gaseous concentration shells'. The theory was tested using the unique measurements of Dow et al. (2014) that have shown lower leaf diffusive conductance for a genotype of Arabidopsis thaliana with clustered stomata relative to uniformly distributed stomata of similar size and density. The model accounts for gaseous diffusion: through stomatal pores; via concentration shells forming at pore apertures that vary with stomata spacing and are thus altered by clustering; and across the adjacent air boundary layer. Analytical approximations were derived and validated using a numerical model for 3D diffusion equation. Stomata clustering increases the interactions among concentration shells resulting in larger diffusive resistance that may reduce fluxes by 5-15%. A similar reduction in conductance was found for clusters formed by networks of veins. The study resolves ambiguities found in the literature concerning stomata end-corrections and stomatal shape, and provides a new stomata density threshold for diffusive interactions of overlapping vapor shells. The predicted reduction in gaseous exchange due to clustering, suggests that guard cell function is impaired, limiting stomatal aperture opening. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  1. 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.

  2. Monte Carlo analysis of thermal transpiration effects in capacitance diaphragm gauges with helicoidal baffle system

    International Nuclear Information System (INIS)

    Vargas, M; Stefanov, S; Wüest, M

    2012-01-01

    The Capacitance Diaphragm Gauge (CDG) is one of the most widely used vacuum gauges in low and middle vacuum ranges. This device consists basically of a very thin ceramic or metal diaphragm which forms one of the electrodes of a cap acitor. The pressure is determined by measuring the variation in the capacitance due to the deflection of the diaphragm caused by the pressure difference established across the membrane. In order to minimize zero drift, some CDGs are operated keeping the sensor at a higher temperature. This difference in the temperature between the sensor and the vacuum chamber makes the behaviour of the gauge non-linear due to thermal transpiration effects. This effect becomes more significant when we move from the transitional flow to the free molecular regime. Besides, CDGs may incorporate different baffle systems to avoid the condensation on the membrane or its contamination. In this work, the thermal transpiration effect on the behaviour of a rarefied gas and on the measurements in a CDG with a helicoidal baffle system is investigated by using the Direct Simulation Monte Carlo method (DSMC). The study covers the behaviour of the system under the whole range of rarefaction, from the continuum up to the free molecular limit and the results are compared with empirical results. Moreover, the influence of the boundary conditions on the thermal transpiration effects is investigated by using Maxwell boundary conditions.

  3. 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.

  4. 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.

  5. 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.

  6. A Rationally Designed Agonist Defines Subfamily IIIA Abscisic Acid Receptors As Critical Targets for Manipulating Transpiration.

    Science.gov (United States)

    Vaidya, Aditya S; Peterson, Francis C; Yarmolinsky, Dmitry; Merilo, Ebe; Verstraeten, Inge; Park, Sang-Youl; Elzinga, Dezi; Kaundal, Amita; Helander, Jonathan; Lozano-Juste, Jorge; Otani, Masato; Wu, Kevin; Jensen, Davin R; Kollist, Hannes; Volkman, Brian F; Cutler, Sean R

    2017-11-17

    Increasing drought and diminishing freshwater supplies have stimulated interest in developing small molecules that can be used to control transpiration. Receptors for the plant hormone abscisic acid (ABA) have emerged as key targets for this application, because ABA controls the apertures of stomata, which in turn regulate transpiration. Here, we describe the rational design of cyanabactin, an ABA receptor agonist that preferentially activates Pyrabactin Resistance 1 (PYR1) with low nanomolar potency. A 1.63 Å X-ray crystallographic structure of cyanabactin in complex with PYR1 illustrates that cyanabactin's arylnitrile mimics ABA's cyclohexenone oxygen and engages the tryptophan lock, a key component required to stabilize activated receptors. Further, its sulfonamide and 4-methylbenzyl substructures mimic ABA's carboxylate and C6 methyl groups, respectively. Isothermal titration calorimetry measurements show that cyanabactin's compact structure provides ready access to high ligand efficiency on a relatively simple scaffold. Cyanabactin treatments reduce Arabidopsis whole-plant stomatal conductance and activate multiple ABA responses, demonstrating that its in vitro potency translates to ABA-like activity in vivo. Genetic analyses show that the effects of cyanabactin, and the previously identified agonist quinabactin, can be abolished by the genetic removal of PYR1 and PYL1, which form subclade A within the dimeric subfamily III receptors. Thus, cyanabactin is a potent and selective agonist with a wide spectrum of ABA-like activities that defines subfamily IIIA receptors as key target sites for manipulating transpiration.

  7. 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.

  8. 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.

  9. 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.

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

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    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.

  11. 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.

  12. Foliar K application delays leaf senescence of winter rape-seed (Brassica napus L.) under waterlogging

    Institute of Scientific and Technical Information of China (English)

    Lin Wan; Chao Hu; Chang Chen; Liyan Zhang; Ni Ma; Chunlei Zhang

    2017-01-01

    To better understand waterlogging effect on leaf senescence in winter rapseed (Brassica napus L.) during flowering stage, experiments were designed to explore foliar K application influences on adverse effects of waterlogging stress. Winter rapeseed was sprayed with K after waterlogging at initial flowering stage. Results indicated that waterlog-ging significantly decreased leaf net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci) and transpiration rate (Tr). It also declined maximum quantum yield of PS II (Fv/Fm), quantum yield of electron transport (ΦPS II) and pho-tochemical quenching (qP), but increased leaf non-photochemical quenching (NPQ) and minimal fluorescence (Fo). Interestingly, exogenous application of K significantly alleviated waterlogging-induced photosynthesis inhibition. Foliar K application increased RuBisCO activation, chlorophyll and soluble protein contents, while significantly decreased MDA con-tent under waterlogging stress. Moreover, K supplementation improved accumulation of K+, Ca2+, Mg2+, N, Zn2+, Mn2+, Fe2+ in leaves. In general, foliar K application is effective in alleviating deleterious effects of waterlogging stress and delays leaf senescence of winter rapeseed.

  13. Sugar and hexokinase suppress expression of PIP aquaporins and reduce leaf hydraulics that preserves leaf water potential.

    Science.gov (United States)

    Kelly, Gilor; Sade, Nir; Doron-Faigenboim, Adi; Lerner, Stephen; Shatil-Cohen, Arava; Yeselson, Yelena; Egbaria, Aiman; Kottapalli, Jayaram; Schaffer, Arthur A; Moshelion, Menachem; Granot, David

    2017-07-01

    Sugars affect central aspects of plant physiology, including photosynthesis, stomatal behavior and the loss of water through the stomata. Yet, the potential effects of sugars on plant aquaporins (AQPs) and water conductance have not been examined. We used database and transcriptional analyses, as well as cellular and whole-plant functional techniques to examine the link between sugar-related genes and AQPs. Database analyses revealed a high level of correlation between the expression of AQPs and that of sugar-related genes, including the Arabidopsis hexokinases 1 (AtHXK1). Increased expression of AtHXK1, as well as the addition of its primary substrate, glucose (Glc), repressed the expression of 10 AQPs from the plasma membrane-intrinsic proteins (PIP) subfamily (PIP-AQPs) and induced the expression of two stress-related PIP-AQPs. The osmotic water permeability of mesophyll protoplasts of AtHXK1-expressing plants and the leaf hydraulic conductance of those plants were significantly reduced, in line with the decreased expression of PIP-AQPs. Conversely, hxk1 mutants demonstrated a higher level of hydraulic conductance, with increased water potential in their leaves. In addition, the presence of Glc reduced leaf water potential, as compared with an osmotic control, indicating that Glc reduces the movement of water from the xylem into the mesophyll. The production of sugars entails a significant loss of water and these results suggest that sugars and AtHXK1 affect the expression of AQP genes and reduce leaf water conductance, to coordinate sugar levels with the loss of water through transpiration. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  14. 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

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. A better way of representing stem area index in two-big-leaf models: the application and impact on canopy integration of leaf nitrogen content

    Science.gov (United States)

    Chen, M.; Butler, E. E.; Wythers, K. R.; Kattge, J.; Ricciuto, D. M.; Thornton, P. E.; Atkin, O. K.; Flores-Moreno, H.; Reich, P. B.

    2017-12-01

    In order to better estimate the carbon budget of the globe, accurately simulating gross primary productivity (GPP) in earth system models is critical. When upscaling leaf level photosynthesis to the canopy, climate models uses different big-leaf schemes. About half of the state-of-the-art earth system models use a "two-big-leaf" scheme that partitions canopies into direct and diffusively illuminated fractions to reduce high bias of GPP simulated by one-big-leaf models. Some two-big-leaf models, such as ACME (identical in this respect to CLM 4.5) add leaf area index (LAI) and stem area index (SAI) together when calculating canopy radiation transfer. This treatment, however, will result in higher fraction of sunlit leaves. It will also lead to an artificial overestimation of canopy nitrogen content. Here we introduce a new algorithm of simulating SAI in a two-big-leaf model. The new algorithm reduced the sunlit leave fraction of the canopy and conserved the nitrogen content from leaf to canopy level. The lower fraction of sunlit leaves reduced global GPP especially in tropical area. Compared to the default model, for the past 100 years (1909-2009), the averaged global annual GPP is lowered by 4.11 PgC year-1 using this new algorithm.

  1. (TECTONA GRANDIS LEAF POWDER

    Directory of Open Access Journals (Sweden)

    Yash Mishra

    2015-01-01

    Full Text Available In this study, the adsorption potential of Teak (Tectona grandis leaf powder (TLP toremove Methylene blue (MB and Malachite Green (MG dye molecules from aqueoussolution was investigated. Batch experiments were conducted to evaluate the influenceof operational parameters such as, pH (2−9, adsorbent dosage (1−7 g/L, contact time(15−150 minutes and initial dye concentration (20−120 mg/L at stirring speed of 150rpm for the adsorption of MB and MG on TLP. Maximum removal efficiency of 98.4%and 95.1% was achieved for MB and MG dye, respectively. The experimentalequilibrium data were analysed using Langmuir, Freundlich and Temkin isothermmodels and it was found that, it fitted well to the Freundlich isotherm model. Thesurface structure and morphology of the adsorbent was characterized using scanningelectron microscopy (SEM and the presence of functional groups and its interactionwith the dye molecules were analysed using Fourier transform infrared spectroscopy(FTIR. Based on the investigation, it has been demonstrated that the teak leaf powderhas good potential for effective adsorption of methylene blue and malachite green dye.

  2. Antibacterial and antioxidant activities of Vaccinium corymbosum L. leaf extract

    Directory of Open Access Journals (Sweden)

    Mehnaz Pervin

    2013-12-01

    Full Text Available Objective: To investigate antibacterial and antioxidant activity of the leaf extract of tropical medicinal herb and food plant Vaccinium corymbosum L. (V. corymbosum . Methods: Free radical scavenging activity on DPPH, ABTS, and nitrites were used to analyse phenolic and flavonoid contents of leaf extract. Other focuses included the determination of antioxidant enzymatic activity (SOD, CAT and GPx, metal chelating activity, reduction power, lipid peroxidation inhibition and the prevention of oxidative DNA damage. Antibacterial activity was determined by using disc diffusion method against seven strains of bacteria. Results: Results found that V. corymbosum leaf extract had significant antibacterial activity. The tested extract displayed the highest activity (about 23.18 mm inhibition zone against Salmonella typhymurium and the lowest antibacterial activity was observed against Enterococcus faecalis (about 14.08 mm inhibition zone at 10 mg/ disc. The IC 50 values for DPPH, ABTS and radical scavenging activity were 0.120, 0.049 and 1.160 mg/mL, respectively. V. corymbosum leaf extract also showed dose dependent reduction power, lipid peroxidation, DNA damage prevention and significant antioxidant enzymatic activity. Conclusions: These findings demonstrate that leaf extract of V. corymbosum could be used as an alternative therapy for antibiotic-resistant bacteria and help prevent various free radical related diseases.

  3. Antibacterial and antioxidant activities of Vaccinium corymbosum L. leaf extract

    Science.gov (United States)

    Pervin, Mehnaz; Hasnat, Md Abul; Lim, Beong Ou

    2013-01-01

    Objective To investigate antibacterial and antioxidant activity of the leaf extract of tropical medicinal herb and food plant Vaccinium corymbosum L. (V. corymbosum). Methods Free radical scavenging activity on DPPH, ABTS, and nitrites were used to analyse phenoic and flavonoid contents of leaf extract. Other focuses included the determination of antioxidant enzymatic activity (SOD, CAT and GPx), metal chelating activity, reduction power, lipid peroxidation inhibition and the prevention of oxidative DNA damage. Antibacterial activity was determined by using disc diffusion for seven strains of bacteria. Results Results found that V. corymbosum leaf extract had significant antibacterial activity. The tested extract displayed the highest activity (about 23.18 mm inhibition zone) against Salmonella typhymurium and the lowest antibacterial activity was observed against Enterococcus faecalis (about 14.08 mm inhibition zone) at 10 mg/ disc. The IC50 values for DPPH, ABTS and radical scavenging activity were 0.120, 0.049 and 1.160 mg/mL, respectively. V. corymbosum leaf extract also showed dose dependent reduction power, lipid peroxidation, DNA damage prevention and significant antioxidant enzymatic activity. Conclusions These findings demonstrate that leaf extract of V. corymbosum could be used as an alternative therapy for antibiotic-resistant bacteria and help prevent various free radical related diseases.

  4. 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.

  5. Fractional Diffusion Equations and Anomalous Diffusion

    Science.gov (United States)

    Evangelista, Luiz Roberto; Kaminski Lenzi, Ervin

    2018-01-01

    Preface; 1. Mathematical preliminaries; 2. A survey of the fractional calculus; 3. From normal to anomalous diffusion; 4. Fractional diffusion equations: elementary applications; 5. Fractional diffusion equations: surface effects; 6. Fractional nonlinear diffusion equation; 7. Anomalous diffusion: anisotropic case; 8. Fractional Schrödinger equations; 9. Anomalous diffusion and impedance spectroscopy; 10. The Poisson–Nernst–Planck anomalous (PNPA) models; References; Index.

  6. Investigation of the vaporization of boric acid by transpiration thermogravimetry and knudsen effusion mass spectrometry.

    Science.gov (United States)

    Balasubramanian, R; Lakshmi Narasimhan, T S; Viswanathan, R; Nalini, S

    2008-11-06

    The vaporization of H3BO3(s) was studied by using a commercial thermogravimetric apparatus and a Knudsen effusion mass spectrometer. The thermogravimetric measurements involved use of argon as the carrier gas for vapor transport and derivation of vapor pressures of H3BO3(g) in the temperature range 315-352 K through many flow dependence and temperature dependence runs. The vapor pressures as well as the enthalpy of sublimation obtained in this study represent the first results from measurements at low temperatures that are in accord with the previously reported near-classical transpiration measurements (by Stackelberg et al. 70 years ago) at higher temperatures (382-413 K with steam as the carrier gas). The KEMS measurements performed for the first time on boric acid showed H3BO3(g) as the principal vapor species with no meaningful information discernible on H2O(g) though. The thermodynamic parameters, both p(H3BO3) and Delta sub H degrees m(H3BO3,g), deduced from KEMS results in the temperature range 295-342 K are in excellent agreement with the transpiration results lending further credibility to the latter. All this information points toward congruent vaporization at the H3BO3 composition in the H2O-B2O3 binary system. The vapor pressures obtained from transpiration (this study and that of Stackelberg et al.) as well as from KEMS measurements are combined to recommend the following: log [p(H3BO3)/Pa]=-(5199+/-74)/(T/K)+(15.65+/-0.23), valid for T=295-413 K; and Delta sub H degrees m=98.3+/-9.5 kJ mol (-1) at T=298 K for H3BO3(s)=H3BO3(g).

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

    International Nuclear Information System (INIS)

    Gao, Lixin; Bai, Hua; Mao, Shufeng

    2014-01-01

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

  9. 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

  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. Photosynthetic limitations in two Antarctic vascular plants: importance of leaf anatomical traits and Rubisco kinetic parameters.

    Science.gov (United States)

    Sáez, Patricia L; Bravo, León A; Cavieres, Lohengrin A; Vallejos, Valentina; Sanhueza, Carolina; Font-Carrascosa, Marcel; Gil-Pelegrín, Eustaquio; Javier Peguero-Pina, José; Galmés, Jeroni

    2017-05-17

    Particular physiological traits allow the vascular plants Deschampsia antarctica Desv. and Colobanthus quitensis (Kunth) Bartl. to inhabit Antarctica. The photosynthetic performance of these species was evaluated in situ, focusing on diffusive and biochemical constraints to CO2 assimilation. Leaf gas exchange, Chl a fluorescence, leaf ultrastructure, and Rubisco catalytic properties were examined in plants growing on King George and Lagotellerie islands. In spite of the species- and population-specific effects of the measurement temperature on the main photosynthetic parameters, CO2 assimilation was highly limited by CO2 diffusion. In particular, the mesophyll conductance (gm)-estimated from both gas exchange and leaf chlorophyll fluorescence and modeled from leaf anatomy-was remarkably low, restricting CO2 diffusion and imposing the strongest constraint to CO2 acquisition. Rubisco presented a high specificity for CO2 as determined in vitro, suggesting a tight co-ordination between CO2 diffusion and leaf biochemistry that may be critical ultimately to optimize carbon balance in these species. Interestingly, both anatomical and biochemical traits resembled those described in plants from arid environments, providing a new insight into plant functional acclimation to extreme conditions. Understanding what actually limits photosynthesis in these species is important to anticipate their responses to the ongoing and predicted rapid warming in the Antarctic Peninsula. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  12. On the estimate of the transpiration in Mediterranean heterogeneous ecosystems with the coupled use of eddy covariance and sap flow techniques.

    Science.gov (United States)

    Corona, Roberto; Curreli, Matteo; Montaldo, Nicola; Oren, Ram

    2013-04-01

    Mediterranean ecosystems are commonly heterogeneous savanna-like ecosystems, with contrasting plant functional types (PFT) competing for the water use. Mediterranean regions suffer water scarcity due to the dry climate conditions. In semi-arid regions evapotranspiration (ET) is the leading loss term of the root-zone water budget with a yearly magnitude that may be roughly equal to the precipitation. Despite the attention these ecosystems are receiving, a general lack of knowledge persists about the estimate of ET and the relationship between ET and the plant survival strategies for the different PFTs under water stress. During the dry summers these water-limited heterogeneous ecosystems are mainly characterized by a simple dual PFT-landscapes with strong-resistant woody vegetation and bare soil since grass died. In these conditions due to the low signal of the land surface fluxes captured by the sonic anemometer and gas analyzer the widely used eddy covariance may fail and its ET estimate is not robust enough. In these conditions the use of the sap flow technique may have a key role, because theoretically it provides a direct estimate of the woody vegetation transpiration. Through the coupled use of the sap flow sensor observations, a 2D foot print model of the eddy covariance tower and high resolution satellite images for the estimate of the foot print land cover map, the eddy covariance measurements can be correctly interpreted, and ET components (bare soil evaporation and woody vegetation transpiration) can be separated. The case study is at the Orroli site in Sardinia (Italy). The site landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and cork oaks, different shrubs and herbaceous species. An extensive field campaign started in 2004. Land-surface fluxes and CO2 fluxes are estimated by an eddy covariance technique based micrometeorological tower. Soil moisture profiles were also continuously estimated using water

  13. Tolerance of citrus plants to the combination of high temperatures and drought is associated to the increase in transpiration modulated by a reduction in abscisic acid levels.

    Science.gov (United States)

    Zandalinas, Sara I; Rivero, Rosa M; Martínez, Vicente; Gómez-Cadenas, Aurelio; Arbona, Vicent

    2016-04-27

    In natural environments, several adverse environmental conditions occur simultaneously constituting a unique stress factor. In this work, physiological parameters and the hormonal regulation of Carrizo citrange and Cleopatra mandarin, two citrus genotypes, in response to the combined action of high temperatures and water deprivation were studied. The objective was to characterize particular responses to the stress combination. Experiments indicated that Carrizo citrange is more tolerant to the stress combination than Cleopatra mandarin. Furthermore, an experimental design spanning 24 h stress duration, heat stress applied alone induced higher stomatal conductance and transpiration in both genotypes whereas combined water deprivation partially counteracted this response. Comparing both genotypes, Carrizo citrange showed higher phostosystem-II efficiency and lower oxidative damage than Cleopatra mandarin. Hormonal profiling in leaves revealed that salicylic acid (SA) accumulated in response to individual stresses but to a higher extent in samples subjected to the combination of heat and drought (showing an additive response). SA accumulation correlated with the up-regulation of pathogenesis-related gene 2 (CsPR2), as a downstream response. On the contrary, abscisic acid (ABA) accumulation was higher in water-stressed plants followed by that observed in plants under stress combination. ABA signaling in these plants was confirmed by the expression of responsive to ABA-related gene 18 (CsRAB18). Modulation of ABA levels was likely carried out by the induction of 9-neoxanthin cis-epoxicarotenoid dioxygenase (CsNCED) and ABA 8'-hydroxylase (CsCYP707A) while conversion to ABA-glycosyl ester (ABAGE) was a less prominent process despite the strong induction of ABA O-glycosyl transferase (CsAOG). Cleopatra mandarin is more susceptible to the combination of high temperatures and water deprivation than Carrizo citrange. This is likely a result of a higher transpiration rate in

  14. Model estimates of leaf area and reference canopy stomatal conductance suggest correlation between phenology and physiology in both trembling aspen and red pine

    Science.gov (United States)

    Mackay, D. S.; Ewers, B. E.; Kruger, E. L.

    2006-12-01

    Phenological variations impact water and carbon fluxes, as evidenced by the large interannual variability of net ecosystem exchange of carbon dioxide and evapotranspiration (ET). In northern Wisconsin we observed daily variations of canopy transpiration from hardwoods from 1.0 to 1.7 mm/day during the leaf unfolding period and 1.7 to 2.6 mm/day with leaves fully out. Correlations between such flux rates and phenology have not been extensively tested and mechanistic connections are in their infancy. Some data suggest that stomatal conductance and photosynthesis increases up to full expansion. Moreover, in conifers, the interaction of phenology and physiology is more complicated than in deciduous trees because needles are retained for several years. Using inverse modeling with a coupled photosynthesis-transpiration model we estimated reference canopy stomatal conductance, Gsref, for red pine (Pinus resinosa), and Gsref and leaf area index, L, for trembling aspen (Populus tremuloides), using 30-min continuous sap flux data spanning a period from just prior to the start of leaf expansion to just after leaf senescence. The red pine showed Gsref ramp up from 105 to 179 mmol m-2 leaf s-1, which represented a 37 to 50 percent increase in Gsref after accounting for maximum possible changes in L. After full leaf out, the trembling aspen were almost immediately defoliated, and then reflushed after three weeks. Model estimates of L reflected this pattern and were consistent with measurements. However, Gsref never exceeded 45 mmol m-2 s-1 prior to defoliation, but peaked at 112 mmol m-2 s-1 after reflushing. These results support the need for further work that aims to separate phenology and physiology.

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

    Science.gov (United States)

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

  16. From Leaf Synthesis to Senescence: n-Alkyl Lipid Abundance and D/H Composition Among Plant Species in a Temperate Deciduous Forest at Brown's Lake Bog, Ohio, USA

    Science.gov (United States)

    Freimuth, E. J.; Diefendorf, A. F.; Lowell, T. V.

    2014-12-01

    The hydrogen isotope composition (D/H, δD) of terrestrial plant leaf waxes is a promising paleohydrology proxy because meteoric water (e.g., precipitation) is the primary hydrogen source for wax synthesis. However, secondary environmental and biological factors modify the net apparent fractionation between precipitation δD and leaf wax δD, limiting quantitative reconstruction of paleohydrology. These secondary factors include soil evaporation, leaf transpiration, biosynthetic fractionation, and the seasonal timing of lipid synthesis. Here, we investigate the influence of each of these factors on n-alkyl lipid δD in five dominant deciduous angiosperm tree species as well as shrubs, ferns and grasses in the watershed surrounding Brown's Lake Bog, Ohio, USA. We quantified n-alkane and n-alkanoic acid concentrations and δD in replicate individuals of each species at weekly to monthly intervals from March to October 2014 to assess inter- and intraspecific isotope variability throughout the growing season. We present soil, xylem and leaf water δD from each individual, and precipitation and atmospheric water vapor δD throughout the season to directly examine the relationship between source water and lipid isotope composition. These data allow us to assess the relative influence of soil evaporation and leaf transpiration among plant types, within species, and along a soil moisture gradient throughout the catchment. We use leaf water δD to approximate biosynthetic fractionation for each individual and test whether this is a species-specific and seasonal constant, and to evaluate variation among plant types with identical growth conditions. Our high frequency sampling approach provides new insights into the seasonal timing of n-alkane and n-alkanoic acid synthesis and subsequent fluctuations in concentration and δD in a temperate deciduous forest. These results will advance understanding of the magnitude and timing of secondary influences on the modern leaf wax

  17. Prediction of transpiration effects on heat and mass transfer by different turbulence models

    International Nuclear Information System (INIS)

    Bucci, M.; Sharabi, M.; Ambrosini, W.; Forgione, N.; Oriolo, F.; He, S.

    2008-01-01

    The paper reports the results of a study related to transpirating flows, stimulated by the interest that these phenomena, occurring in the presence of simultaneous heat and mass transfer, have for nuclear reactor applications. The work includes a summary and the follow-up of previous experimental and numerical investigations on filmwise condensation and falling film evaporation and of a recent review of different forms of the heat and mass transfer analogy. The particular objective here pursued is to compare transpiration effects as predicted by different turbulence models with classical suction and blowing multipliers based on stagnant layer theories, in the attempt to clarify their quantitative implications on the predicted mass transfer rates. A commercial and an in-house CFD code have been adopted for evaluating the heat and mass transfer rates occurring over a flat plate exposed to an air-vapour stream, with uniform bulk steam mass fraction and temperature boundary conditions at the wall. This simple configuration was purposely selected since it is a simplified representation of the test section of an experimental facility presently in operation at the University of Pisa. This allows a direct comparison between the heat and mass transfer coefficients predicted by CFD models and classical correlations for Nusselt and Sherwood numbers

  18. 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.

  19. 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

  20. [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.

  1. 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.

  2. 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.

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

    Directory of Open Access Journals (Sweden)

    Zahoor Ahmad BHAT

    2011-03-01

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

  4. Rapid hydraulic recovery in Eucalyptus pauciflora after drought: linkages between stem hydraulics and leaf gas exchange.

    Science.gov (United States)

    Martorell, Sebastià; Diaz-Espejo, Antonio; Medrano, Hipólito; Ball, Marilyn C; Choat, Brendan

    2014-03-01

    In woody plants, photosynthetic capacity is closely linked to rates at which the plant hydraulic system can supply water to the leaf surface. Drought-induced embolism can cause sharp declines in xylem hydraulic conductivity that coincide with stomatal closure and reduced photosynthesis. Recovery of photosynthetic capacity after drought is dependent on restored xylem function, although few data exist to elucidate this coordination. We examined the dynamics of leaf gas exchange and xylem function in Eucalyptus pauciflora seedlings exposed to a cycle of severe water stress and recovery after re-watering. Stomatal closure and leaf turgor loss occurred at water potentials that delayed the extensive spread of embolism through the stem xylem. Stem hydraulic conductance recovered to control levels within 6 h after re-watering despite a severe drought treatment, suggesting an active mechanism embolism repair. However, stomatal conductance did not recover after 10 d of re-watering, effecting tighter control of transpiration post drought. The dynamics of recovery suggest that a combination of hydraulic and non-hydraulic factors influenced stomatal behaviour post drought. © 2013 John Wiley & Sons Ltd.

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

    Directory of Open Access Journals (Sweden)

    Michelle Sliwinski

    2013-09-01

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

  6. Agave Americana Leaf Fibers

    Directory of Open Access Journals (Sweden)

    Ashish Hulle

    2015-02-01

    Full Text Available The growing environmental problems, the problem of waste disposal and the depletion of non-renewable resources have stimulated the use of green materials compatible with the environment to reduce environmental impacts. Therefore, there is a need to design products by using natural resources. Natural fibers seem to be a good alternative since they are abundantly available and there are a number of possibilities to use all the components of a fiber-yielding crop; one such fiber-yielding plant is Agave Americana. The leaves of this plant yield fibers and all the parts of this plant can be utilized in many applications. The “zero-waste” utilization of the plant would enable its production and processing to be translated into a viable and sustainable industry. Agave Americana fibers are characterized by low density, high tenacity and high moisture absorbency in comparison with other leaf fibers. These fibers are long and biodegradable. Therefore, we can look this fiber as a sustainable resource for manufacturing and technical applications. Detailed discussion is carried out on extraction, characterization and applications of Agave Americana fiber in this paper.

  7. Diffusion bonding

    International Nuclear Information System (INIS)

    Anderson, R.C.

    1976-01-01

    A method is described for joining beryllium to beryllium by diffusion bonding. At least one surface portion of at least two beryllium pieces is coated with nickel. A coated surface portion is positioned in a contiguous relationship with another surface portion and subjected to an environment having an atmosphere at a pressure lower than ambient pressure. A force is applied on the beryllium pieces for causing the contiguous surface portions to abut against each other. The contiguous surface portions are heated to a maximum temperature less than the melting temperature of the beryllium, and the applied force is decreased while increasing the temperature after attaining a temperature substantially above room temperature. A portion of the applied force is maintained at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions

  8. Multipassage diffuser

    International Nuclear Information System (INIS)

    Lalis, A.; Rouviere, R.; Simon, G.

    1976-01-01

    A multipassage diffuser having 2p passages comprises a leak-tight cylindrical enclosure closed by a top cover and a bottom end-wall, parallel porous tubes which are rigidly assembled in sectors between tube plates and through which the gas mixture flows, the tube sectors being disposed at uniform intervals on the periphery of the enclosure. The top tube plates are rigidly fixed to an annular header having the shape of a half-torus and adapted to communicate with the tubes of the corresponding sector. Each passage is constituted by a plurality of juxtaposed sectors in which the mixture circulates in the same direction, the header being divided into p portions limited by radial partition-walls and each constituting two adjacent passages. The diffuser is provided beneath the bottom end-wall with p-1 leak-tight chambers each adapted to open into two different portions of the header, and with two collector-chambers each fitted with a nozzle for introducing the gas mixture and discharging the fraction of the undiffused mixture. By means of a central orifice formed in the bottom end-wall the enclosure communicates with a shaft for discharging the diffused fraction of the gas mixture

  9. 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.

  10. 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

  11. 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...

  12. A Global Data Set of Leaf Photosynthetic Rates, Leaf N and P, and Specific Leaf Area

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This global data set of photosynthetic rates and leaf nutrient traits was compiled from a comprehensive literature review. It includes estimates of Vcmax...

  13. A Global Data Set of Leaf Photosynthetic Rates, Leaf N and P, and Specific Leaf Area

    Data.gov (United States)

    National Aeronautics and Space Administration — This global data set of photosynthetic rates and leaf nutrient traits was compiled from a comprehensive literature review. It includes estimates of Vcmax (maximum...

  14. Effects of Psidium guajava Leaf Infusion on Streptococci viridans

    Directory of Open Access Journals (Sweden)

    Hing Yi Chen

    2016-09-01

    Full Text Available Background: Dental caries is recognized as the most important oral burden. It is caused by the formation of lactate acid formed through reaction of bacteria and carbohydrates. Streptococci viridans has been proven as the primary etiologic agents for dental caries. Low accessibility in oral care services leads the Indonesian community to use plants in order to prevent dental caries. One of those plants is Psidium guajava (pink guava. The leaves were suggested to have antimicrobial effects on some gram-positive bacteria. When the organism is resistant to specific substance tested on media, a circular/inhibition zone around a disc containing antimicrobial substance was formed. The purpose of this study was to identify the presence of inhibition zones by infusion of Psidium guajava leaf on Streptococci viridians in vitro. Methods: This laboratory experiment was carried out in September to October 2014 at the Microbiology Laboratory, Faculty of Medicine, Universitas Padjadjaran. Infusions of Psidium guajava leaf were made into four different concentrations (10%, 25%, 50% and 100%, respectively and the identification of inhibition zones on Streptococci viridans obtained from the laboratory was tested using modified disk diffusion test. Distilled water acted as negative control. The results were then interpreted after 24 hours of incubation. Every procedure was repeated three times. Results: All four concentrations of Psidium guajava leaf infusions have formed inhibition zones on the media, with the highest concentration (100% producing largest average diameter. Conclusions: The infusion of Psidium guajava leaf produces inhibition zones on Streptococci virdans in vitro.

  15. RNAi-mediated downregulation of poplar plasma membrane intrinsic proteins (PIPs) changes plasma membrane proteome composition and affects leaf physiology.

    Science.gov (United States)

    Bi, Zhen; Merl-Pham, Juliane; Uehlein, Norbert; Zimmer, Ina; Mühlhans, Stefanie; Aichler, Michaela; Walch, Axel Karl; Kaldenhoff, Ralf; Palme, Klaus; Schnitzler, Jörg-Peter; Block, Katja

    2015-10-14

    Plasma membrane intrinsic proteins (PIPs) are one subfamily of aquaporins that mediate the transmembrane transport of water. To reveal their function in poplar, we generated transgenic poplar plants in which the translation of PIP genes was downregulated by RNA interference investigated these plants with a comprehensive leaf plasma membrane proteome and physiome analysis. First, inhibition of PIP synthesis strongly altered the leaf plasma membrane protein composition. Strikingly, several signaling components and transporters involved in the regulation of stomatal movement were differentially regulated in transgenic poplars. Furthermore, hormonal crosstalk related to abscisic acid, auxin and brassinosteroids was altered, in addition to cell wall biosynthesis/cutinization, the organization of cellular structures and membrane trafficking. A physiological analysis confirmed the proteomic results. The leaves had wider opened stomata and higher net CO2 assimilation and transpiration rates as well as greater mesophyll conductance for CO2 (gm) and leaf hydraulic conductance (Kleaf). Based on these results, we conclude that PIP proteins not only play essential roles in whole leaf water and CO2 flux but have important roles in the regulation of stomatal movement. Copyright © 2015. Published by Elsevier B.V.

  16. [Effects of soil moisture content and light intensity on the plant growth and leaf physiological characteristics of squash].

    Science.gov (United States)

    Du, She-ni; Bai, Gang-shuan; Liang, Yin-li

    2011-04-01

    A pot experiment with artificial shading was conducted to study the effects of soil moisture content and light intensity on the plant growth and leaf physiological characteristics of squash variety "Jingyingyihao". Under all test soil moisture conditions, 30% shading promoted the growth of "Jingyingyihao", with the highest yield at 70% - 80% soil relative moisture contents. 70% shading inhibited plant growth severely, only flowering and not bearing fruits, no economic yield produced. In all treatments, there was a similar water consumption trend, i. e., both the daily and the total water consumption decreased with increasing shading and decreasing soil moisture content. Among all treatments, 30% shading and 70% - 80% soil relative moisture contents had the highest water use efficiency (2.36 kg mm(-1) hm(-2)) and water output rate (1.57 kg mm(-1) hm(-2)). The net photosynthetic rate, transpiration rate, stomatal conductance, and chlorophyll content of squash leaves decreased with increasing shading, whereas the intercellular CO2 concentration was in adverse. The leaf protective enzyme activity and proline content decreased with increasing shading, and the leaf MAD content decreased in the order of 70% shading, natural radiation, and 30% shading. Under the three light intensities, the change characteristics of squash leaf photosynthesis, protective enzyme activity, and proline and MAD contents differed with the increase of soil relative moisture content.

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

    Science.gov (United States)

    Sharma, Dew Kumari; Andersen, Sven Bode; Ottosen, Carl-Otto; Rosenqvist, Eva

    2015-02-01

    The chlorophyll fluorescence parameter Fv /Fm reflects the maximum quantum efficiency of photosystem II (PSII) photochemistry and has been widely used for early stress detection in plants. Previously, we have used a three-tiered approach of phenotyping by Fv /Fm to identify naturally existing genetic variation for tolerance to severe heat stress (3 days at 40°C in controlled conditions) in wheat (Triticum aestivum L.). Here we investigated the performance of the previously selected cultivars (high and low group based on Fv /Fm value) in terms of growth and photosynthetic traits under moderate heat stress (1 week at 36/30°C day/night temperature in greenhouse) closer to natural heat waves in North-Western Europe. Dry matter accumulation after 7 days of heat stress was positively correlated to Fv /Fm . The high Fv /Fm group maintained significantly higher total chlorophyll and net photosynthetic rate (PN ) than the low group, accompanied by higher stomatal conductance (gs ), transpiration rate (E) and evaporative cooling of the leaf (ΔT). The difference in PN between the groups was not caused by differences in PSII capacity or gs as the variation in Fv /Fm and intracellular CO2 (Ci ) was non-significant under the given heat stress. This study validated that our three-tiered approach of phenotyping by Fv /Fm performed under increasing severity of heat was successful in identifying wheat cultivars differing in photosynthesis under moderate and agronomically more relevant heat stress. The identified cultivars may serve as a valuable resource for further studies to understand the physiological mechanisms underlying the genetic variability in heat sensitivity of photosynthesis. © 2014 Scandinavian Plant Physiology Society.

  18. High transpiration efficiency increases pod yield under intermittent drought in dry and hot atmospheric conditions but less so under wetter and cooler conditions in groundnut (Arachis hypogaea (L.)).

    Science.gov (United States)

    Vadez, Vincent; Ratnakumar, Pasala

    2016-07-01

    Water limitation is a major yield limiting factor in groundnut and transpiration efficiency (TE) is considered the main target for improvement, but TE being difficult to measure it has mostly been screened with surrogates. The paper re-explore the contribution of TE to grain yield in peanut by using a novel experimental approach in which TE is measured gravimetrically throughout the crop life cycle, in addition to measurement of TE surrogates. Experimentation was carried out with the groundnut reference collection (n = 288), across seasons varying for the evaporative demand (vapor pressure deficit, VPD) and across both fully irrigated and intermittent water stress conditions. There was large genotypic variation for TE under water stress in both low and high VPD season but the range was larger (5-fold) in the high- than in the low-VPD season (2-fold). Under water stress in both seasons, yield was closely related to the harvest index (HI) while TE related directly to yield only in the high VPD season. After discounting the direct HI effect on yield, TE explained a large portion of the remaining yield variations in both seasons, although marginally in the low VPD season. By contrast, the total water extracted from the soil profile, which varied between genotypes, did not relate directly to pod yield and neither to the yield residuals unexplained by HI. Surrogates for TE (specific leaf area, SLA, and SPAD chlorophyll meter readings, SCMR) never showed any significant correlation to TE measurements. Therefore, TE is an important factor explaining yield differences in groundnut under high VPD environments, suggesting that stomatal regulation under high VPD, rather than high photosynthetic rate as proposed earlier, may have a key role to play in the large TE differences found, which open new opportunities to breed improved groundnut for high VPD.

  19. 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

  20. Estimation of beech tree transpiration in relation to their social status in forest stand

    International Nuclear Information System (INIS)

    Střelcová, K.; Matejka, F.; Minďáš, J.

    2002-01-01

    The results of sap flow continuous measurements by a tree-trunk heat balance method (THB) on beech model trees are analysed in this paper. Experimental research works were carried out in a mature mixed fir-spruce-beech stand in the research area Pol'ana - Hukavský Grúň (φ = 48°39', λ = 19°29', H = 850 m a.s.l.) in UNESCO Biosphere Reserve on two co-dominant and one sub-dominant beech trees. A mathematical model of daily transpiration dynamics was proposed for a quantitative analysis of the daily course of sap flow intensity. The model works on a one-tree level and enables to consider the influence of the tree social position in the stand on the sap flow intensity of model beech trees and to express the dependence of sap flow intensity on the tree height and crown projection

  1. Absence of Hg transpiration by shoot after Hg uptake by roots of six terrestrial plant species

    International Nuclear Information System (INIS)

    Greger, Maria; Wang Yaodong; Neuschuetz, Clara

    2005-01-01

    In this paper we investigated if, and to what extent, six different plant species accumulate, translocate and emit mercury (Hg) into the air. The Hg uptake by roots, distribution of Hg to the shoot and release of Hg via shoots of garden pea, spring wheat, sugar beet, oil-seed rape, white clover and willow were investigated in a transpiration chamber. The airborne Hg was trapped in a Hopcalite trap or a gold trap. Traps and plant materials were analysed for content of Hg by CVAAS. The results show that all plant species were able to take up Hg to a large extent from a nutrient solution containing 200 μg L -1 Hg. However, the Hg translocation to the shoot was low (0.17-2.5%) and the Hg that reached the leaves was trapped and no release of the absorbed Hg to the air was detected. - Mercury translocation to shoots was low

  2. Quantum diffusion

    International Nuclear Information System (INIS)

    Habib, S.

    1994-01-01

    We consider a simple quantum system subjected to a classical random force. Under certain conditions it is shown that the noise-averaged Wigner function of the system follows an integro-differential stochastic Liouville equation. In the simple case of polynomial noise-couplings this equation reduces to a generalized Fokker-Planck form. With nonlinear noise injection new ''quantum diffusion'' terms rise that have no counterpart in the classical case. Two special examples that are not of a Fokker-Planck form are discussed: the first with a localized noise source and the other with a spatially modulated noise source

  3. 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...

  4. 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...

  5. 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...

  6. Comparative measurements of transpiration an canopy conductance in two mixed deciduous woodlands differing in structure and species composition

    DEFF Research Database (Denmark)

    Herbst, Mathias; Rosier, Paul T.W.; Morecroft, Michael D.

    2008-01-01

    a continuous hazel (Corylus avellana L.) understory. Wytham Woods, which had an LAI of 3.6, was dominated by ash (Fraxinus excelsior L.) and sycamore (Acer pseudoplatanus L.) and had only a sparse understory. Annual canopy transpiration was 367 mm for Grimsbury Wood and 397 mm for Wytham Woods. These values...

  7. 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.

  8. 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...

  9. 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.

  10. 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

  11. Hereditary Diffuse Gastric Cancer

    Science.gov (United States)

    ... Hereditary Diffuse Gastric Cancer Request Permissions Hereditary Diffuse Gastric Cancer Approved by the Cancer.Net Editorial Board , 10/2017 What is hereditary diffuse gastric cancer? Hereditary diffuse gastric cancer (HDGC) is a rare ...

  12. Study of vaporization of sodium metaborate by transpiration thermogravimetry and Knudsen effusion mass spectrometry.

    Science.gov (United States)

    Narasimhan, T S Lakshmi; Viswanathan, R; Nalini, S

    2011-11-17

    The vaporization of solid sodium metaborate NaBO(2)(s) was studied by transpiration thermogravimetry (TTG) and Knudsen effusion mass spectrometry (KEMS). The transpiration measurements, performed for the first time on NaBO(2)(s), involved use of argon as the carrier gas for vapor transport and derivation of vapor pressure of NaBO(2)(g) (by assuming it as the sole vapor species) through many flow-dependence runs and temperature-dependence runs in the temperature range 1075-1218 K. The KEMS measurements performed in the temperature range 1060-1185 K confirmed NaBO(2)(g) as the principal vapor species over NaBO(2)(s), in accord with the previously reported KEMS studies. The values of p(NaBO(2)) obtained by both TTG and KEMS are consistent within the uncertainties associated with each method and so are the second- and third-law values of enthalpy of sublimation, the latter aspect consistently missing in all previous vaporization studies. The results of both TTG and KEMS were combined to recommend the following thermodynamic parameters pertinent to the sublimation reaction, NaBO(2)(s) = NaBO(2)(g): Log{p(NaBO(2))/Pa} = -(17056 ± 441)/(T/K) + (14.73 ± 0.35) for the temperature range 1060-1218 K; Δ(r)H°(m)(298.15 K) = (346.3 ± 9.4) kJ·mol(-1); and Δ(r)S°(m)(298.15 K) = (210.2 ± 6.8) J·mol(-1)·K(-1).

  13. 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.

  14. 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.

  15. Antifungal activity of Piper aduncum and Peperomia pellucida leaf ethanol extract against Candida albicans

    Science.gov (United States)

    Hastuti, Utami Sri; Ummah, Yunita Putri Irsadul; Khasanah, Henny Nurul

    2017-05-01

    This research was done to 1) examine the effect of Piper aduncum leaf ethanol extract at certain concentrations against Candida albicans colony growth inhibition in vitro; 2) examine the effect of Peperomia pellucida leaf ethanol extract at certain concentrations toward Candida albicans colony growth inhibition in vitro; and 3) determine the most effective concentration of P. aduncum and P. pellucida leaves ethanol extract against C. albicans colony growth inhibition in vitro. These plant extracts were prepared by the maceration technique using 95% ethanol, and then sterile filtered and evaporated to obtain the filtrate. The filtrate was diluted with sterile distilled water at certain concentrations, i.e.: 0%, 10%, 20%, 30%, 405, 50%, 60%, 70%, 80%, and 90%. The antifungal effect of each leaf extract concentration was examined by the agar diffusion method on Sabouraud Dextrose Agar medium. The research results are: 1) the P.aduncum leaf ethanol extract at some concentrations has an effect against C. albicans colony growth inhibition in vitro; 2) the P.pellucida leaf ethanol extract at some concentrations has an effect against C. albicans colony growth inhibition in vitro; 3) the P. aduncum leaf ethanol extract at 80% is the most effective for C. albicans colony growth inhibition in vitro; and 4) the P. pellucida leaf ethanol extract at 70% is the most effective for C. albicans colony growth inhibition in vitro.

  16. Transformation of Leaf-like Zinc Dendrite in Oxidation and Reduction Cycle

    International Nuclear Information System (INIS)

    Nakata, Akiyoshi; Murayama, Haruno; Fukuda, Katsutoshi; Yamane, Tomokazu; Arai, Hajime; Hirai, Toshiro; Uchimoto, Yoshiharu; Yamaki, Jun-ichi; Ogumi, Zempachi

    2015-01-01

    Highlights: • Leaf-like zinc dendrites change to leaf-like residual oxides at high oxidation current density (10 mA cm −2 ) whereas it completely dissolves at low oxidation current density (1 mA cm −2 ). • Leaf-like residual oxide products is transformed to zinc deposits with particulate morphology, resulting in good rechargeability. • The residual zinc oxide provides sufficient zincate on its reduction, preventing the diffusion-limited condition that causes leaf-like dendrite formation. - Abstract: Zinc is a promising negative electrode material for aqueous battery systems whereas it shows insufficient rechargeability for use in secondary batteries. It has been reported that leaf-like dendrite deposits are often the origin of cell-failure, however, their nature and behavior on discharge (oxidation) - charge (reduction) cycling have been only poorly understood. Here we investigate the transformation of the leaf-like zinc dendrites using ex-situ scanning electron microscopy, X-ray computational tomography and in-situ X-ray diffraction. It is shown that the leaf-like zinc dendrites obtained under diffusion-limited conditions are nearly completely dissolved at a low oxidation current density of 1 mA cm −2 and cause re-evolution of the zinc dendrites. Oxidation at a high current density of 10 mA cm −2 leads to the formation of leaf-like zinc oxide residual products that result in particulate zinc deposits in the following reduction process, enabling good rechargeability. The reaction behavior of this oxide residue is detailed and discussed for the development of long-life zinc electrodes

  17. Coordination and transport of water and carbohydrates in the coupled soil-root-xylem-phloem leaf system

    Science.gov (United States)

    Katul, Gabriel; Huang, Cheng-Wei

    2017-04-01

    In response to varying environmental conditions, stomatal pores act as biological valves that dynamically adjust their size thereby determining the rate of CO2 assimilation and water loss (i.e., transpiration) to the atmosphere. Although the significance of this biotic control on gas exchange is rarely disputed, representing parsimoniously all the underlying mechanisms responsible for stomatal kinetics remain a subject of some debate. It has been conjectured that stomatal control in seed plants (i.e., angiosperm and gymnosperm) represents a compromise between biochemical demand for CO2 and prevention of excessive water loss. This view has been amended at the whole-plant level, where xylem hydraulics and sucrose transport efficiency in phloem appear to impose additional constraints on gas exchange. If such additional constraints impact stomatal opening and closure, then seed plants may have evolved coordinated photosynthetic-hydraulic-sugar transporting machinery that confers some competitive advantages in fluctuating environmental conditions. Thus, a stomatal optimization model that explicitly considers xylem hydraulics and maximum sucrose transport is developed to explore this coordination in the leaf-xylem-phloem system. The model is then applied to progressive drought conditions. The main findings from the model calculations are that (1) the predicted stomatal conductance from the conventional stomatal optimization theory at the leaf and the newly proposed models converge, suggesting a tight coordination in the leaf-xylem-phloem system; (2) stomatal control is mainly limited by the water supply function of the soil-xylem hydraulic system especially when the water flux through the transpiration stream is significantly larger than water exchange between xylem and phloem; (3) thus, xylem limitation imposed on the supply function can be used to differentiate species with different water use strategy across the spectrum of isohydric to anisohydric behavior.

  18. Leaf out times of temperate woody plants are related to phylogeny, deciduousness, growth habit and wood anatomy.

    Science.gov (United States)

    Panchen, Zoe A; Primack, Richard B; Nordt, Birgit; Ellwood, Elizabeth R; Stevens, Albert-Dieter; Renner, Susanne S; Willis, Charles G; Fahey, Robert; Whittemore, Alan; Du, Yanjun; Davis, Charles C

    2014-09-01

    Leaf out phenology affects a wide variety of ecosystem processes and ecological interactions and will take on added significance as leaf out times increasingly shift in response to warming temperatures associated with climate change. There is, however, relatively little information available on the factors affecting species differences in leaf out phenology. An international team of researchers from eight Northern Hemisphere temperate botanical gardens recorded leaf out dates of c. 1600 woody species in 2011 and 2012. Leaf out dates in woody species differed by as much as 3 months at a single site and exhibited strong phylogenetic and anatomical relationships. On average, angiosperms leafed out earlier than gymnosperms, deciduous species earlier than evergreen species, shrubs earlier than trees, diffuse and semi-ring porous species earlier than ring porous species, and species with smaller diameter xylem vessels earlier than species with larger diameter vessels. The order of species leaf out was generally consistent between years and among sites. As species distribution and abundance shift due to climate change, interspecific differences in leaf out phenology may affect ecosystem processes such as carbon, water, and nutrient cycling. Our open access leaf out data provide a critical framework for monitoring and modelling such changes going forward. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  19. Phenotypic selection on leaf water use efficiency and related ecophysiological traits for natural populations of desert sunflowers.

    Science.gov (United States)

    Donovan, Lisa A; Dudley, Susan A; Rosenthal, David M; Ludwig, Fulco

    2007-05-01

    Plant water-use efficiency (WUE) is expected to affect plant fitness and thus be under natural selection in arid habitats. Although many natural population studies have assessed plant WUE, only a few related WUE to fitness. The further determination of whether selection on WUE is direct or indirect through functionally related traits has yielded no consistent results. For natural populations of two desert annual sunflowers, Helianthus anomalus and H. deserticola, we used phenotypic selection analysis with vegetative biomass as the proxy for fitness to test (1) whether there was direct and indirect selection on WUE (carbon isotope ratio) and related traits (leaf N, area, succulence) and (2) whether direct selection was consistent with hypothesized drought/dehydration escape and avoidance strategies. There was direct selection for lower WUE in mesic and dry H. anomalus populations, consistent with dehydration escape, even though it is the longer lived of the two species. For mesic H. anomalus, direct selection favored lower WUE and higher N, suggesting that plants may be "wasting water" to increase N delivery via the transpiration stream. For the shorter lived H. deserticola in the direr habitat, there was indirect selection for lower WUE, inconsistent with drought escape. There was also direct selection for higher leaf N, succulence and leaf size. There was no direct selection for higher WUE consistent with dehydration avoidance in either species. Thus, in these natural populations of two desert dune species higher fitness was associated with some combination direct and indirect selection for lower WUE, higher leaf N and larger leaf size. Our understanding of the adaptive value of plant ecophysiological traits will benefit from further consideration of related traits such as leaf nitrogen and more tests in natural populations.

  20. Mesophyll conductance in Zea mays responds transiently to CO2 availability: implications for transpiration efficiency in C4 crops.

    Science.gov (United States)

    Kolbe, Allison R; Cousins, Asaph B

    2018-03-01

    Mesophyll conductance (g m ) describes the movement of CO 2 from the intercellular air spaces below the stomata to the site of initial carboxylation in the mesophyll. In contrast with C 3 -g m , little is currently known about the intraspecific variation in C 4 -g m or its responsiveness to environmental stimuli. To address these questions, g m was measured on five maize (Zea mays) lines in response to CO 2 , employing three different estimates of g m . Each of the methods indicated a significant response of g m to CO 2 . Estimates of g m were similar between methods at ambient and higher CO 2 , but diverged significantly at low partial pressures of CO 2 . These differences are probably driven by incomplete chemical and isotopic equilibrium between CO 2 and bicarbonate under these conditions. Carbonic anhydrase and phosphoenolpyruvate carboxylase in vitro activity varied significantly despite similar values of g m and leaf anatomical traits. These results provide strong support for a CO 2 response of g m in Z. mays, and indicate that g m in maize is probably driven by anatomical constraints rather than by biochemical limitations. The CO 2 response of g m indicates a potential role for facilitated diffusion in C 4 -g m . These results also suggest that water-use efficiency could be enhanced in C 4 species by targeting g m . © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  1. Waiting for the Leaf; Warten auf den Leaf

    Energy Technology Data Exchange (ETDEWEB)

    Wilms, Jan

    2012-01-15

    Nissan will be the first manufacturer to launch an electric vehicle of the VW Golf category in the German market. With a mileage of about 170 km and a roomy passenger compartment, the Leaf promises much comfort. In the US market, it was launched two years ago. Was it worth while waiting for?.

  2. Effect of nitrogen supply on leaf appearance, leaf growth, leaf nitrogen economy and photosynthetic capacity in maize (Zea mays L.)

    NARCIS (Netherlands)

    Vos, J.; Putten, van der P.E.L.; Birch, C.J.

    2005-01-01

    Leaf area growth and nitrogen concentration per unit leaf area, Na (g m-2 N) are two options plants can use to adapt to nitrogen limitation. Previous work indicated that potato (Solanum tuberosum L.) adapts the size of leaves to maintain Na and photosynthetic capacity per unit leaf area. This paper

  3. Short-term responses of leaf growth rate to water deficit scale up to whole-plant and crop levels: an integrated modelling approach in maize.

    Science.gov (United States)

    Chenu, Karine; Chapman, Scott C; Hammer, Graeme L; McLean, Greg; Salah, Halim Ben Haj; Tardieu, François

    2008-03-01

    Physiological and genetic studies of leaf growth often focus on short-term responses, leaving a gap to whole-plant models that predict biomass accumulation, transpiration and yield at crop scale. To bridge this gap, we developed a model that combines an existing model of leaf 6 expansion in response to short-term environmental variations with a model coordinating the development of all leaves of a plant. The latter was based on: (1) rates of leaf initiation, appearance and end of elongation measured in field experiments; and (2) the hypothesis of an independence of the growth between leaves. The resulting whole-plant leaf model was integrated into the generic crop model APSIM which provided dynamic feedback of environmental conditions to the leaf model and allowed simulation of crop growth at canopy level. The model was tested in 12 field situations with contrasting temperature, evaporative demand and soil water status. In observed and simulated data, high evaporative demand reduced leaf area at the whole-plant level, and short water deficits affected only leaves developing during the stress, either visible or still hidden in the whorl. The model adequately simulated whole-plant profiles of leaf area with a single set of parameters that applied to the same hybrid in all experiments. It was also suitable to predict biomass accumulation and yield of a similar hybrid grown in different conditions. This model extends to field conditions existing knowledge of the environmental controls of leaf elongation, and can be used to simulate how their genetic controls flow through to yield.

  4. Spectral reflectance relationships to leaf water stress

    Science.gov (United States)

    Ripple, William J.

    1986-01-01

    Spectral reflectance data were collected from detached snapbean leaves in the laboratory with a multiband radiometer. Four experiments were designed to study the spectral response resulting from changes in leaf cover, relative water content of leaves, and leaf water potential. Spectral regions included in the analysis were red (630-690 nm), NIR (760-900 nm), and mid-IR (2.08-2.35 microns). The red and mid-IR bands showed sensitivity to changes in both leaf cover and relative water content of leaves. The NIR was only highly sensitive to changes in leaf cover. Results provided evidence that mid-IR reflectance was governed primarily by leaf moisture content, although soil reflectance was an important factor when leaf cover was less than 100 percent. High correlations between leaf water potentials and reflectance were attributed to covariances with relative water content of leaves and leaf cover.

  5. Adaptative changes of leaf surface of tropical orchid Cattleya gaskelliana (N.E.Br. B.S. Williams after transferring from in vitro to ex vitro conditions

    Directory of Open Access Journals (Sweden)

    Lyudmila I. Buyun

    2013-04-01

    Full Text Available The leaf surface micromorphology of Cattleya gaskellianajuvenile plants, propagated in vitrofrom seeds, as well as of adult plants, cultivated in glasshouse, was analyzed by scanning electron microscopy (SEM. The leaves of both juvenile and adult plants are hypostomatic, their stomata are of tetracytic type. It was found that development of single stomata on the adaxial leaf surface of juvenile plants was induced byin vitro conditions. During the acclimation of in vitro propagated plants to glasshouse conditions the following changes of leaf surface micromorphology have been observed: 1 configuration of epidermal cells changed; 2 dimensions of typical epidermal cells reduced; 3 stomata density and their dimensions increased. The results suggest that structural changes, probably, can be regarded as an adaptation to avoid excessive rate leaf transpiration during a period of C. gaskelliana juvenile plants acclimation to glasshouse conditions. In the case when micromorphological leaf characteristics (stomata density per mm2, stomatal index, epidermal cells number per mm 2 of in vitro propagated plants of C. gaskelliana were comparable to those of adult plants, survival rate was more than 95%.

  6. An evolutionary perspective on leaf economics : Phylogenetics of leaf mass per area in vascular plants

    NARCIS (Netherlands)

    Flores, Olivier; Garnier, Eric; Wright, Ian J.; Reich, Peter B.; Pierce, Simon; Diaz, Sandra; Pakeman, Robin J.; Rusch, Graciela M.; Bernard-Verdier, Maud; Testi, Baptiste; Bakker, Jan P.; Bekker, Renee M.; Cerabolini, Bruno E. L.; Ceriani, Roberta M.; Cornu, Guillaume; Cruz, Pablo; Delcamp, Matthieu; Dolezal, Jiri; Eriksson, Ove; Fayolle, Adeline; Freitas, Helena; Golodets, Carly; Gourlet-Fleury, Sylvie; Hodgson, John G.; Brusa, Guido; Kleyer, Michael; Kunzmann, Dieter; Lavorel, Sandra; Papanastasis, Vasilios P.; Perez-Harguindeguy, Natalia; Vendramini, Fernanda; Weiher, Evan

    In plant leaves, resource use follows a trade-off between rapid resource capture and conservative storage. This "worldwide leaf economics spectrum" consists of a suite of intercorrelated leaf traits, among which leaf mass per area, LMA, is one of the most fundamental as it indicates the cost of leaf

  7. The Nissan LEAF electric powertrain

    Energy Technology Data Exchange (ETDEWEB)

    Nakazawa, Shinsuke [Nissan Motor Co., Ltd. (Japan)

    2011-07-01

    The need for CO{sub 2} reduction as a countermeasure to global warming, and to move away from our dependence on fossil fuels as a countermeasure to energy security are urgent issues. One of the ultimate goals to achieving these targets is to develop a 'Zero emission car' such as an electric vehicle or a fuel cell vehicle, along with the manufacturing of clean energy. Nissan have developed a new powertrain for the electric vehicle, and have installed it in the Nissan LEAF. Sales of the Nissan LEAF started in North America, Europe and Japan in 2010, with plans to sell it globally by 2012. In order to achieve an improved driving range, power performance and drivability performance, Nissan have adapted a high efficiency synchronous motor, a water-cooled inverter, and reducer. Moreover, the Nissan LEAF has the capability of a 3.3kW AC charge and a 50kW DC quick charge. This presentation will introduce the features of the electric powertrain adopted for Nissan LEAF. (orig.)

  8. 7 CFR 30.2 - Leaf tobacco.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.2 Leaf...

  9. 7 CFR 29.3035 - Leaf structure.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements...

  10. 7 CFR 29.6023 - Leaf structure.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its...

  11. 7 CFR 29.1030 - Leaf structure.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

  12. 7 CFR 29.3527 - Leaf structure.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

  13. 7 CFR 29.3526 - Leaf scrap.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling...

  14. 7 CFR 29.3034 - Leaf scrap.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and...

  15. 7 CFR 29.6022 - Leaf scrap.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results...

  16. Toward an improved understanding of the role of transpiration in critical zone dynamics

    Science.gov (United States)

    Mitra, B.; Papuga, S. A.

    2012-12-01

    Evapotranspiration (ET) is an important component of the total water balance across any ecosystem. In subalpine mixed-conifer ecosystems, transpiration (T) often dominates the total water flux and therefore improved understanding of T is critical for accurate assessment of catchment water balance and for understanding of the processes that governs the complex dynamics across critical zone (CZ). The interaction between T and plant vegetation not only modulates soil water balance but also influences water transit time and hydrochemical flux - key factors in our understanding of how the CZ evolves and responds. Unlike an eddy covariance system which provides only an integrated ET flux from an ecosystem, a sap flow system can provide an estimate of the T flux from the ecosystem. By isolating T, the ecohydrological drivers of this major water loss from the CZ can be identified. Still, the species composition of mixed-conifer ecosystems vary and the drivers of T associated with each species are expected to be different. Therefore, accurate quantification of T from a mixed-conifer requires knowledge of the unique transpiration dynamics of each of the tree species. Here, we installed a sap flow system within two mixed-conifer study sites of the Jemez River Basin - Santa Catalina Mountains Critical Zone Observatory (JRB - SCM CZO). At both sites, we identified the dominant tree species and installed sap flow sensors on healthy representatives for each of those species. At the JRB CZO site, sap sensors were installed in fir (4) and spruce (4) trees; at the SCM CZO site, sap sensors were installed at white fir (4) and maple (4) and one dead tree. Meteorological data as well as soil temperature (Ts) and soil moisture (θ) at multiple depths were also collected from each of the two sites. Preliminary analysis of two years of sap flux rate at JRB - SCM CZO shows that the environmental drivers of fir, spruce, and maple are different and also vary throughout the year. For JRB fir

  17. Betel leaf in stoma care.

    Science.gov (United States)

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

    2007-07-01

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

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

    Science.gov (United States)

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

    1998-05-01

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

  20. Diffusion archeology for diffusion progression history reconstruction.

    Science.gov (United States)

    Sefer, Emre; Kingsford, Carl

    2016-11-01

    Diffusion through graphs can be used to model many real-world processes, such as the spread of diseases, social network memes, computer viruses, or water contaminants. Often, a real-world diffusion cannot be directly observed while it is occurring - perhaps it is not noticed until some time has passed, continuous monitoring is too costly, or privacy concerns limit data access. This leads to the need to reconstruct how the present state of the diffusion came to be from partial diffusion data. Here, we tackle the problem of reconstructing a diffusion history from one or more snapshots of the diffusion state. This ability can be invaluable to learn when certain computer nodes are infected or which people are the initial disease spreaders to control future diffusions. We formulate this problem over discrete-time SEIRS-type diffusion models in terms of maximum likelihood. We design methods that are based on submodularity and a novel prize-collecting dominating-set vertex cover (PCDSVC) relaxation that can identify likely diffusion steps with some provable performance guarantees. Our methods are the first to be able to reconstruct complete diffusion histories accurately in real and simulated situations. As a special case, they can also identify the initial spreaders better than the existing methods for that problem. Our results for both meme and contaminant diffusion show that the partial diffusion data problem can be overcome with proper modeling and methods, and that hidden temporal characteristics of diffusion can be predicted from limited data.

  1. On the use of leaf spectral indices to assess water status and photosynthetic limitations in Olea europaea L. during water-stress and recovery.

    Science.gov (United States)

    Sun, Pengsen; Wahbi, Said; Tsonev, Tsonko; Haworth, Matthew; Liu, Shirong; Centritto, Mauro

    2014-01-01

    Diffusional limitations to photosynthesis, relative water content (RWC), pigment concentrations and their association with reflectance indices were studied in olive (Olea europaea) saplings subjected to water-stress and re-watering. RWC decreased sharply as drought progressed. Following rewatering, RWC gradually increased to pre-stress values. Photosynthesis (A), stomatal conductance (gs), mesophyll conductance (gm), total conductance (gt), photochemical reflectance index (PRI), water index (WI) and relative depth index (RDI) closely followed RWC. In contrast, carotenoid concentration, the carotenoid to chlorophyll ratio, water content reflectance index (WCRI) and structural independent pigment index (SIPI) showed an opposite trend to that of RWC. Photosynthesis scaled linearly with leaf conductance to CO2; however, A measured under non-photorespiratory conditions (A1%O2) was approximately two times greater than A measured at 21% [O2], indicating that photorespiration likely increased in response to drought. A1%O2 also significantly correlated with leaf conductance parameters. These relationships were apparent in saturation type curves, indicating that under non-photorespiratory conditions, CO2 conductance was not the major limitations to A. PRI was significant correlated with RWC. PRI was also very sensitive to pigment concentrations and photosynthesis, and significantly tracked all CO2 conductance parameters. WI, RDI and WCRI were all significantly correlated with RWC, and most notably to leaf transpiration. Overall, PRI correlated more closely with carotenoid concentration than SIPI; whereas WI tracked leaf transpiration more effectively than RDI and WCRI. This study clearly demonstrates that PRI and WI can be used for the fast detection of physiological traits of olive trees subjected to water-stress.

  2. Response of Eustoma Leaf Phenotype and Photosynthetic Performance to LED Light Quality

    Directory of Open Access Journals (Sweden)

    Md Zohurul Kadir Roni

    2017-10-01

    Full Text Available In a controlled environment, light from light-emitting diodes (LEDs has been associated with affecting the leaf characteristics of Eustoma. LEDs help plant growth and development, yet little is known about photosynthetic performance and related anatomical features in the early growth stage of Eustoma leaves. In this study, we examined the effects of blue (B, red (R, and white (W LEDs on the photosynthetic performance of Eustoma leaves, as well as leaf morphology and anatomy including epidermal layer thickness, palisade cells, and stomatal characteristics. Leaves grown under B LEDs were thicker and had a higher chlorophyll content than those grown under the R and W LEDs. Leaves under B LEDs had greater net photosynthetic rates (A, stomatal conductance (gs, and transpiration rates (E, especially at a higher photon flux density (PPFD, that resulted in a decrease in the intercellular CO2 concentration (Ci, than leaves under the W and R LEDs. B LEDs resulted in greater abaxial epidermal layer thickness and palisade cell length and width than the R and W LED treatments. The palisade cells also developed a more cylindrical shape in response to the B LEDs. B LED leaves also showed greater guard cell length, breadth, and area, and stomatal density, than W or R LEDs, which may contribute to increased A, gs and E at higher PPFDs.

  3. 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.

  4. Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles

    Science.gov (United States)

    Hanquist, Kyle M.; Hara, Kentaro; Boyd, Iain D.

    2017-02-01

    Electron transpiration cooling (ETC) is a recently proposed approach to manage the high heating loads experienced at the sharp leading edges of hypersonic vehicles. Computational fluid dynamics (CFD) can be used to investigate the feasibility of ETC in a hypersonic environment. A modeling approach is presented for ETC, which includes developing the boundary conditions for electron emission from the surface, accounting for the space-charge limit effects of the near-wall plasma sheath. The space-charge limit models are assessed using 1D direct-kinetic plasma sheath simulations, taking into account the thermionically emitted electrons from the surface. The simulations agree well with the space-charge limit theory proposed by Takamura et al. for emitted electrons with a finite temperature, especially at low values of wall bias, which validates the use of the theoretical model for the hypersonic CFD code. The CFD code with the analytical sheath models is then used for a test case typical of a leading edge radius in a hypersonic flight environment. The CFD results show that ETC can lower the surface temperature of sharp leading edges of hypersonic vehicles, especially at higher velocities, due to the increase in ionized species enabling higher electron heat extraction from the surface. The CFD results also show that space-charge limit effects can limit the ETC reduction of surface temperatures, in comparison to thermionic emission assuming no effects of the electric field within the sheath.

  5. 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.

  6. A simplified method for evaluating thermal performance of unglazed transpired solar collectors under steady state

    International Nuclear Information System (INIS)

    Wang, Xiaoliang; Lei, Bo; Bi, Haiquan; Yu, Tao

    2017-01-01

    Highlights: • A simplified method for evaluating thermal performance of UTC is developed. • Experiments, numerical simulations, dimensional analysis and data fitting are used. • The correlation of absorber plate temperature for UTC is established. • The empirical correlation of heat exchange effectiveness for UTC is proposed. - Abstract: Due to the advantages of low investment and high energy efficiency, unglazed transpired solar collectors (UTC) have been widely used for heating in buildings. However, it is difficult for designers to quickly evaluate the thermal performance of UTC based on the conventional methods such as experiments and numerical simulations. Therefore, a simple and fast method to determine the thermal performance of UTC is indispensable. The objective of this work is to provide a simplified calculation method to easily evaluate the thermal performance of UTC under steady state. Different parameters are considered in the simplified method, including pitch, perforation diameter, solar radiation, solar absorptivity, approach velocity, ambient air temperature, absorber plate temperature, and so on. Based on existing design parameters and operating conditions, correlations for the absorber plate temperature and the heat exchange effectiveness are developed using dimensional analysis and data fitting, respectively. Results show that the proposed simplified method has a high accuracy and can be employed to evaluate the collector efficiency, the heat exchange effectiveness and the air temperature rise. The proposed method in this paper is beneficial to directly determine design parameters and operating status for UTC.

  7. Plant delta 15N correlates with the transpiration efficiency of nitrogen acquisition in tropical trees.

    Science.gov (United States)

    Cernusak, Lucas A; Winter, Klaus; Turner, Benjamin L

    2009-11-01

    Based upon considerations of a theoretical model of (15)N/(14)N fractionation during steady-state nitrate uptake from soil, we hypothesized that, for plants grown in a common soil environment, whole-plant delta(15)N (deltaP) should vary as a function of the transpiration efficiency of nitrogen acquisition (F(N)/v) and the difference between deltaP and root delta(15)N (deltaP - deltaR). We tested these hypotheses with measurements of several tropical tree and liana species. Consistent with theoretical expectations, both F(N)/v and deltaP - deltaR were significant sources of variation in deltaP, and the relationship between deltaP and F(N)/v differed between non-N(2)-fixing and N(2)-fixing species. We interpret the correlation between deltaP and F(N)/v as resulting from variation in mineral nitrogen efflux-to-influx ratios across plasma membranes of root cells. These results provide a simple explanation of variation in delta(15)N of terrestrial plants and have implications for understanding nitrogen cycling in ecosystems.

  8. 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.

  9. Matériaux architecturés pour refroidissement par transpiration : application aux chambres de combustion

    OpenAIRE

    Pinson , Sébastien

    2016-01-01

    In order to cool aero-engine combustion chambers as efficiently as possible, there is today a special interest given to transpiration cooling technology. The cooling air flows through a porous liner in which a large amount of heat can be exchanged by convection. The air injection could then take benefit of the pore distribution to form a more homogeneous protective boundary layer.Partially sintered metallic materials are potential candidates to form these porous liners. The present work focus...

  10. Optimal allocation of leaf epidermal area for gas exchange.

    Science.gov (United States)

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

    2016-06-01

    A long-standing research focus in phytology has been to understand how plants allocate leaf epidermal space to stomata in order to achieve an economic balance between the plant's carbon needs and water use. Here, we present a quantitative theoretical framework to predict allometric relationships between morphological stomatal traits in relation to leaf gas exchange and the required allocation of epidermal area to stomata. Our theoretical framework was derived from first principles of diffusion and geometry based on the hypothesis that selection for higher anatomical maximum stomatal conductance (gsmax ) involves a trade-off to minimize the fraction of the epidermis that is allocated to stomata. Predicted allometric relationships between stomatal traits were tested with a comprehensive compilation of published and unpublished data on 1057 species from all major clades. In support of our theoretical framework, stomatal traits of this phylogenetically diverse sample reflect spatially optimal allometry that minimizes investment in the allocation of epidermal area when plants evolve towards higher gsmax . Our results specifically highlight that the stomatal morphology of angiosperms evolved along spatially optimal allometric relationships. We propose that the resulting wide range of viable stomatal trait combinations equips angiosperms with developmental and evolutionary flexibility in leaf gas exchange unrivalled by gymnosperms and pteridophytes. © 2016 The Authors New Phytologist © 2016 New Phytologist Trust.

  11. 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

  12. 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.

  13. Validation of a simple evaporation-transpiration scheme (SETS) to estimate evaporation using micro-lysimeter measurements

    Science.gov (United States)

    Ghazanfari, Sadegh; Pande, Saket; Savenije, Hubert

    2014-05-01

    Several methods exist to estimate E and T. The Penman-Montieth or Priestly-Taylor methods along with the Jarvis scheme for estimating vegetation resistance are commonly used to estimate these fluxes as a function of land cover, atmospheric forcing and soil moisture content. In this study, a simple evaporation transpiration method is developed based on MOSAIC Land Surface Model that explicitly accounts for soil moisture. Soil evaporation and transpiration estimated by SETS is validated on a single column of soil profile with measured evaporation data from three micro-lysimeters located at Ferdowsi University of Mashhad synoptic station, Iran, for the year 2005. SETS is run using both implicit and explicit computational schemes. Results show that the implicit scheme estimates the vapor flux close to that by the explicit scheme. The mean difference between the implicit and explicit scheme is -0.03 mm/day. The paired T-test of mean difference (p-Value = 0.042 and t-Value = 2.04) shows that there is no significant difference between the two methods. The sum of soil evaporation and transpiration from SETS is also compared with P-M equation and micro-lysimeters measurements. The SETS predicts the actual evaporation with a lower bias (= 1.24mm/day) than P-M (= 1.82 mm/day) and with R2 value of 0.82.

  14. 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.

  15. Fusaric acid is a crucial factor in the disturbance of leaf water imbalance in Fusarium-infected banana plants.

    Science.gov (United States)

    Dong, Xian; Ling, Ning; Wang, Min; Shen, Qirong; Guo, Shiwei

    2012-11-01

    Fusarium wilt of banana is caused by Fusarium oxysporum f. sp. cubense infection. The initial chlorosis symptoms occur progressively from lower to upper leaves, with wilt symptoms subsequently occurring in the whole plant. To determine the effect of the pathogen infection on the gas exchange characteristics and water content in banana leaves, hydroponic experiments with pathogen inoculation were conducted in a greenhouse. Compared with control plants, infected banana seedlings showed a higher leaf temperature as determined by thermal imaging. Reduced stomatal conductance (g(s)) and transpiration rate (E) in infected plants resulted in lower levels of water loss than in control plants. Water potential in heavily diseased plants (II) was significantly reduced and the E/g(s) ratio was higher than in noninfected plants, indicating the occurrence of uncontrolled water loss not regulated by stomata in diseased plants. As no pathogen colonies were detected from the infected plant leaves, the crude toxin was extracted from the pathogen culture and evaluated about the effect on banana plant to further investigate the probable reason of these physiological changes in Fusarium-infected banana leaf. The phytotoxin fusaric acid (FA) was found in the crude toxin, and both crude toxin and pure FA had similar effects as the pathogen infection on the physiological changes in banana leaf. Additionally, FA was present at all positions in diseased plants and its concentration was positively correlated with the incidence of disease symptoms. Taken together, these observations indicated that FA secreted by the pathogen is an important factor involved in the disturbance of leaf temperature, resulting in uncontrolled leaf water loss and electrolyte leakage due to damaging the cell membrane. In conclusion, FA plays a critical role in accelerating the development of Fusarium wilt in banana plants by acting as a phytotoxin. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  16. Effects of fully open-air [CO2] elevation on leaf photosynthesis and ultrastructure of Isatis indigotica fort.

    Science.gov (United States)

    Hao, Xingyu; Li, Ping; Feng, Yongxiang; Han, Xue; Gao, Ji; Lin, Erda; Han, Yuanhuai

    2013-01-01

    Traditional Chinese medicine relies heavily on herbs, yet there is no information on how these herb plants would respond to climate change. In order to gain insight into such response, we studied the effect of elevated [CO2] on Isatis indigotica Fort, one of the most popular Chinese herb plants. The changes in leaf photosynthesis, chlorophyll fluorescence, leaf ultrastructure and biomass yield in response to elevated [CO2] (550±19 µmol mol(-1)) were determined at the Free-Air Carbon dioxide Enrichment (FACE) experimental facility in North China. Photosynthetic ability of I. indigotica was improved under elevated [CO2]. Elevated [CO2] increased net photosynthetic rate (P N), water use efficiency (WUE) and maximum rate of electron transport (J max) of upper most fully-expended leaves, but not stomatal conductance (gs), transpiration ratio (Tr) and maximum velocity of carboxylation (V c,max). Elevated [CO2] significantly increased leaf intrinsic efficiency of PSII (Fv'/Fm') and quantum yield of PSII(ΦPS II ), but decreased leaf non-photochemical quenching (NPQ), and did not affect leaf proportion of open PSII reaction centers (qP) and maximum quantum efficiency of PSII (Fv/Fm). The structural chloroplast membrane, grana layer and stroma thylakoid membranes were intact under elevated [CO2], though more starch grains were accumulated within the chloroplasts than that of under ambient [CO2]. While the yield of I. indigotica was higher due to the improved photosynthesis under elevated [CO2], the content of adenosine, one of the functional ingredients in indigowoad root was not affected.

  17. Analysis of Peanut Leaf Proteome

    DEFF Research Database (Denmark)

    Ramesh, R.; Suravajhala, Prashanth; Pechan, T.

    2010-01-01

    Peanut (Arachis hypogaea) is one of the most important sources of plant protein. Current selection of genotypes requires molecular characterization of available populations. Peanut genome database has several EST cDNAs which can be used to analyze gene expression. Analysis of proteins is a direct...... approach to define function of their associated genes. Proteome analysis linked to genome sequence information is critical for functional genomics. However, the available protein expression data is extremely inadequate. Proteome analysis of peanut leaf was conducted using two-dimensional gel...... electrophoresis in combination with sequence identification using MALDI/TOF to determine their identity and function related to growth, development and responses to stresses. Peanut leaf proteins were resolved into 300 polypeptides with pI values between 3.5 and 8.0 and relative molecular masses from 12 to 100 k...

  18. Contrasting dynamics of leaf potential and gas exchange during progressive drought cycles and recovery in Amorpha fruticosa and Robinia pseudoacacia.

    Science.gov (United States)

    Yan, Weiming; Zheng, Shuxia; Zhong, Yangquanwei; Shangguan, Zhouping

    2017-06-30

    Leaf gas exchange is closely associated with water relations; however, less attention has been given to this relationship over successive drought events. Dynamic changes in gas exchange and water potential in the seedlings of two woody species, Amorpha fruticosa and Robinia pseudoacacia, were monitored during recurrent drought. The pre-dawn leaf water potential declined in parallel with gas exchange in both species, and sharp declines in gas exchange occurred with decreasing water potential. A significant correlation between pre-dawn water potential and gas exchange was observed in both species and showed a right shift in R. pseudoacacia in the second drought. The results suggested that stomatal closure in early drought was mediated mainly by elevated foliar abscisic acid (ABA) in R. pseudoacacia, while a shift from ABA-regulated to leaf-water-potential-driven stomatal closure was observed in A. fruticosa. After re-watering, the pre-dawn water potential recovered quickly, whereas stomatal conductance did not fully recover from drought in R. pseudoacacia, which affected the ability to tightly control transpiration post-drought. The dynamics of recovery from drought suggest that stomatal behavior post-drought may be restricted mainly by hydraulic factors, but non-hydraulic factors may also be involved in R. pseudoacacia.

  19. Excess Entropy and Diffusivity

    Indian Academy of Sciences (India)

    First page Back Continue Last page Graphics. Excess Entropy and Diffusivity. Excess entropy scaling of diffusivity (Rosenfeld,1977). Analogous relationships also exist for viscosity and thermal conductivity.

  20. Homeostasis in leaf water potentials on leeward and windward sides of desert shrub crowns: water loss control vs. high hydraulic efficiency.

    Science.gov (United States)

    Iogna, Patricia A; Bucci, Sandra J; Scholz, Fabián G; Goldstein, Guillermo

    2013-11-01

    Phenotypic plasticity in morphophysiological leaf traits in response to wind was studied in two dominant shrub species of the Patagonian steppe, used as model systems for understanding effects of high wind speed on leaf water relations and hydraulic properties of small woody plants. Morpho-anatomical traits, hydraulic conductance and conductivity and water relations in leaves of wind-exposed and protected crown sides were examined during the summer with nearly continuous high winds. Although exposed sides of the crowns were subjected to higher wind speeds and air saturation deficits than the protected sides, leaves throughout the crown had similar minimum leaf water potential (ΨL). The two species were able to maintain homeostasis in minimum ΨL using different physiological mechanisms. Berberis microphylla avoided a decrease in the minimum ΨL in the exposed side of the crown by reducing water loss by stomatal control, loss of cell turgor and low epidermal conductance. Colliguaja integerrima increased leaf water transport efficiency to maintain transpiration rates without increasing the driving force for water loss in the wind-exposed crown side. Leaf physiological changes within the crown help to prevent the decrease of minimum ΨL and thus contribute to the maintenance of homeostasis, assuring the hydraulic integrity of the plant under unfavorable conditions. The responses of leaf traits that contribute to mechanical resistance (leaf mass per area and thickness) differed from those of large physiological traits by exhibiting low phenotypic plasticity. The results of this study help us to understand the unique properties of shrubs which have different hydraulic architecture compared to trees.

  1. Plasticity in the Huber value contributes to homeostasis in leaf water relations of a mallee Eucalypt with variation to groundwater depth.

    Science.gov (United States)

    Carter, Jennifer L; White, Donald A

    2009-11-01

    Information on how vegetation adapts to differences in water supply is critical for predicting vegetation survival, growth and water use, which, in turn, has important impacts on site hydrology. Many field studies assess adaptation to water stress by comparing between disparate sites, which makes it difficult to distinguish between physiological or morphological changes and long-term genetic adaptation. When planting trees into new environments, the phenotypic adaptations of a species to water stress will be of primary interest. This study examined the response to water availability of Eucalyptus kochii ssp. borealis (C. Gardner) D. Nicolle, commonly integrated with agriculture in south-western Australia for environmental and economic benefits. By choosing a site where the groundwater depth varied but where climate and soil type were the same, we were able to isolate tree response to water supply. Tree growth, leaf area and stand water use were much larger for trees over shallow groundwater than for trees over a deep water table below a silcrete hardpan. However, water use on a leaf area basis was similar in trees over deep and shallow groundwater, as were the minimum leaf water potential observed over different seasons and the turgor loss point. We conclude that homeostasis in leaf water use and water relations was maintained through a combination of stomatal control and adjustment of sapwood-to-leaf area ratios (Huber value). Differences in the Huber value with groundwater depth were associated with different sapwood-specific conductivity and water use on a sapwood area basis. Knowledge of the coordination between water supply, leaf area, sapwood area and leaf transpiration rate for different species will be important when predicting stand water use.

  2. Disruption of mycorrhizal extraradical mycelium and changes in leaf water status and soil aggregate stability in rootbox-grown trifoliate orange

    Directory of Open Access Journals (Sweden)

    Ying-Ning eZou

    2015-03-01

    Full Text Available Arbuscular mycorrhizas possess well developed extraradical mycelium (ERM network that enlarge the surrounding soil for better acquisition of water and nutrients, besides soil aggregation. Distinction in ERM functioning was studied under a rootbox system, which consisted of root+hyphae and root-free hyphae compartments separated by 37-μm nylon mesh with an air gap. Trifoliate orange (Poncirus trifoliata seedlings were inoculated with Funneliformis mosseae in root+hyphae compartment, and the ERM network was established between the two compartments. The ERM network of air gap was disrupted before 8 h of the harvest (one time disruption or multiple disruptions during seedlings acclimation. Our results showed that mycorrhizal inoculation induced a significant increase in growth (plant height, stem diameter, and leaf, stem, and root biomass and physiological characters (leaf relative water content, leaf water potential, and transpiration rate, irrespective of ERM status. Easily-extractable glomalin-related soil protein (EE-GRSP and total GRSP (T-GRSP concentration and mean weight diameter (MWD, an indicator of soil aggregate stability were significantly higher in mycorrhizosphere of root+hyphae and root-free hyphae compartments than non-mycorrhizosphere. One time disruption of ERM network did not influence plant growth and soil properties but only notably decreased leaf water. Periodical disruption of ERM network at weekly interval markedly inhibited the mycorrhizal roles on plant growth, leaf water, GRSP production, and MWD in root+hyphae and hyphae chambers. EE-GRSP was the most responsive GRSP fraction to changes in leaf water and MWD under root+hyphae and hyphae conditions. It suggests that effect of peridical disruption of ERM network was more impactful than one-time disruption of ERM network with regard to leaf water, plant growth, and aggregate stability responses, thereby, implying ERM network aided in developing the host plant metabolically

  3. Can Leaf Spectroscopy Predict Leaf and Forest Traits Along a Peruvian Tropical Forest Elevation Gradient?

    Science.gov (United States)

    Doughty, Christopher E.; Santos-Andrade, P. E.; Goldsmith, G. R.; Blonder, B.; Shenkin, A.; Bentley, L. P.; Chavana-Bryant, C.; Huaraca-Huasco, W.; Díaz, S.; Salinas, N.; Enquist, B. J.; Martin, R.; Asner, G. P.; Malhi, Y.

    2017-11-01

    High-resolution spectroscopy can be used to measure leaf chemical and structural traits. Such leaf traits are often highly correlated to other traits, such as photosynthesis, through the leaf economics spectrum. We measured VNIR (visible-near infrared) leaf reflectance (400-1,075 nm) of sunlit and shaded leaves in 150 dominant species across ten, 1 ha plots along a 3,300 m elevation gradient in Peru (on 4,284 individual leaves). We used partial least squares (PLS) regression to compare leaf reflectance to chemical traits, such as nitrogen and phosphorus, structural traits, including leaf mass per area (LMA), branch wood density and leaf venation, and "higher-level" traits such as leaf photosynthetic capacity, leaf water repellency, and woody growth rates. Empirical models using leaf reflectance predicted leaf N and LMA (r2 > 30% and %RMSE < 30%), weakly predicted leaf venation, photosynthesis, and branch density (r2 between 10 and 35% and %RMSE between 10% and 65%), and did not predict leaf water repellency or woody growth rates (r2<5%). Prediction of higher-level traits such as photosynthesis and branch density is likely due to these traits correlations with LMA, a trait readily predicted with leaf spectroscopy.

  4. Plant water use efficiency over geological time--evolution of leaf stomata configurations affecting plant gas exchange.

    Science.gov (United States)

    Assouline, Shmuel; Or, Dani

    2013-01-01

    Plant gas exchange is a key process shaping global hydrological and carbon cycles and is often characterized by plant water use efficiency (WUE - the ratio of CO2 gain to water vapor loss). Plant fossil record suggests that plant adaptation to changing atmospheric CO2 involved correlated evolution of stomata density (d) and size (s), and related maximal aperture, amax . We interpreted the fossil record of s and d correlated evolution during the Phanerozoic to quantify impacts on gas conductance affecting plant transpiration, E, and CO2 uptake, A, independently, and consequently, on plant WUE. A shift in stomata configuration from large s-low d to small s-high d in response to decreasing atmospheric CO2 resulted in large changes in plant gas exchange characteristics. The relationships between gas conductance, gws , A and E and maximal relative transpiring leaf area, (amax ⋅d), exhibited hysteretic-like behavior. The new WUE trend derived from independent estimates of A and E differs from established WUE-CO2 trends for atmospheric CO2 concentrations exceeding 1,200 ppm. In contrast with a nearly-linear decrease in WUE with decreasing CO2 obtained by standard methods, the newly estimated WUE trend exhibits remarkably stable values for an extended geologic period during which atmospheric CO2 dropped from 3,500 to 1,200 ppm. Pending additional tests, the findings may affect projected impacts of increased atmospheric CO2 on components of the global hydrological cycle.

  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. 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

  7. 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

  8. Cadmium tolerance of Typha domingensis Pers. (Typhaceae as related to growth and leaf morphophysiology

    Directory of Open Access Journals (Sweden)

    J. P. V. Oliveira

    2017-11-01

    Full Text Available Abstract Typha domingensis (cattail is a native macrophyte known by its capacity to tolerate several heavy metals effects and the potential use for phytoremediation. However, in despite that cadmium (Cd is one of the most toxic pollutants; its effects in T. domingensis biology remain uninvestigated. Thus, the objective of this study was to study the tolerance of T. domingensis to cadmium contamination by evaluating its growth, Cd uptake, leaf anatomy and gas exchange. The experiment was designed using three cadmium concentrations (0, 10 and 50 µM and ten replicates for 90 days. The cadmium uptake, growth, gas exchange, chlorophyll content and leaf anatomy were evaluated. Data was submitted to ANOVA and Scott-Knott test for P<0.05. Typha domingensis accumulates Cd proportionally to its concentration on the solution and the content of this metal was higher in roots as compared to shoots. Plants showed no significant modifications on growth parameters such as the biomass production, number of leaves, number of clones and the biomass allocation to organs. The photosynthesis, transpiration and chlorophyll content were not modified by Cd. Most anatomical traits evaluated were not modified by the metal but the stomatal density and the proportion of vascular tissues were reduced under 50 µM of Cd. In despite, the leaf anatomy showed no toxicity evidences for any Cd level. The absence of growth reduction and the stability of anatomical and physiological traits give insight about the Cd tolerance of this species. Therefore, T. domingensis is able to overcome Cd toxicity and shows potential for phytoremediation.

  9. Antimicrobial activity of Piper nigrum L. and Cassia didymobotyra L. leaf extract on selected food borne pathogens

    Directory of Open Access Journals (Sweden)

    Mohd. Sayeed Akthar

    2014-09-01

    Full Text Available Objective: To investigate the antimicrobial activity of leaf extract of Piper nigrum (P. nigrum and Cassia didymobotyra (C. didymobotyra (aqueous, methanol, ethanol and petroleum ether against the food borne pathogenic bacteria [Staphylococcus aureus (S. aureus, Escherichia coli (E. coli, Salmonella typhimurium and Pseudomonas aeruginosa] and fungi [Aspergillus spp. and Candida albicans (C. albicans] and also to investigate the presence of various phytochemicals in the leaf extracts of tested plants. Methods: The antimicrobial activity was determined by disc diffusion method. Minimum inhibitory concentration (MIC, minimum bactericidal and fungicidal concentration were determined by serial dilution method. Results: Methanol leaf extract of test plants exhibited greater antimicrobial activity against the selected bacterial and fungal strains. The MIC results showed that ethanol, methanol and petroleum ether leaf extract of P. nigrum inhibited the growth of S. aureus and E. coli at concentration of 12.5 mg/mL. While, ethanol and methanol leaf extracts of C. didymobotyra inhibited the growth of S. aureus at concentration of 6.25 mg/mL. The MIC values for ethanol, methanol and petroleum ether leaf extract of P. nigrum inhibited the growth of C. albicans at concentration of 25.0 mg/mL. While, it was reported that at concentration of 12.5 mg/mL methanol leaf extract of P. nigrum was against the Aspergillus spp. The MIC values of methanol leaf extract of C. didymobotyra inhibited the growth of C. albicans and Aspergillus spp. at concentration of 12.5 mg/mL and 6.25 mg/mL, respectively. The minimum bactericidal concentration of ethanol, methanol leaf extract of P. nigrum for E. coli and ethanol, methanol leaf extract of C. didymobotyra for S. aureus was recorded at concentration 12.5 mg/mL. The minimum fungicidal concentration of ethanol and methanol leaf extract of P. nigrum and C. didymobotyra on C. albicans was recorded at concentration of 25.0 mg

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

    Science.gov (United States)

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

    2017-12-01

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

  11. 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.

  12. 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.

  13. 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.

  14. Diffusing diffusivity: Rotational diffusion in two and three dimensions

    Science.gov (United States)

    Jain, Rohit; Sebastian, K. L.

    2017-06-01

    We consider the problem of calculating the probability distribution function (pdf) of angular displacement for rotational diffusion in a crowded, rearranging medium. We use the diffusing diffusivity model and following our previous work on translational diffusion [R. Jain and K. L. Sebastian, J. Phys. Chem. B 120, 3988 (2016)], we show that the problem can be reduced to that of calculating the survival probability of a particle undergoing Brownian motion, in the presence of a sink. We use the approach to calculate the pdf for the rotational motion in two and three dimensions. We also propose new dimensionless, time dependent parameters, αr o t ,2 D and αr o t ,3 D, which can be used to analyze the experimental/simulation data to find the extent of deviation from the normal behavior, i.e., constant diffusivity, and obtain explicit analytical expressions for them, within our model.

  15. Diffusion in solids

    International Nuclear Information System (INIS)

    Tiwari, G.P.; Kale, G.B.; Patil, R.V.

    1999-01-01

    The article presents a brief survey of process of diffusion in solids. It is emphasised that the essence of diffusion is the mass transfer through the atomic jumps. To begin with formal equations for diffusion coefficient are presented. This is followed by discussions on mechanisms of diffusion. Except for solutes which form interstitial solid solution, diffusion in majority of cases is mediated through exchange of sites between an atom and its neighbouring vacancy. Various vacancy parameters such as activation volume, correlation factor, mass effect etc are discussed and their role in establishing the mode of diffusion is delineated. The contribution of dislocations and grain boundaries in diffusion process is brought out. The experimental determination of different types of diffusion coefficients are described. Finally, the pervasive nature of diffusion process in number of commercial processes is outlined to show the importance of diffusion studies in materials science and technology. (author)

  16. Enhancement of crop photosynthesis by diffuse light: quantifying the contributing factors.

    Science.gov (United States)

    Li, T; Heuvelink, E; Dueck, T A; Janse, J; Gort, G; Marcelis, L F M

    2014-07-01

    Plants use diffuse light more efficiently than direct light. However, experimental comparisons between diffuse and direct light have been obscured by co-occurring differences in environmental conditions (e.g. light intensity). This study aims to analyse the factors that contribute to an increase in crop photosynthesis in diffuse light and to quantify their relative contribution under different levels of diffuseness at similar light intensities. The hypothesis is that the enhancement of crop photosynthesis in diffuse light results not only from the direct effects of more uniform vertical and horizontal light distribution in the crop canopy, but also from crop physiological and morphological acclimation. Tomato (Solanum lycopersicum) crops were grown in three greenhouse compartments that were covered by glass with different degrees of light diffuseness (0, 45 and 71 % of the direct light being converted into diffuse light) while maintaining similar light transmission. Measurements of horizontal and vertical photosynthetic photon flux density (PPFD) distribution in the crop, leaf photosynthesis light response curves and leaf area index (LAI) were used to quantify each factor's contribution to an increase in crop photosynthesis in diffuse light. In addition, leaf temperature, photoinhibition, and leaf biochemical and anatomical properties were studied. The highest degree of light diffuseness (71 %) increased the calculated crop photosynthesis by 7·2 %. This effect was mainly attributed to a more uniform horizontal (33 % of the total effect) and vertical PPFD distribution (21 %) in the crop. In addition, plants acclimated to the high level of diffuseness by gaining a higher photosynthetic capacity of leaves in the middle of the crop and a higher LAI, which contributed 23 and 13 %, respectively, to the total increase in crop photosynthesis in diffuse light. Moreover, diffuse light resulted in lower leaf temperatures and less photoinhibition at the top of the canopy when

  17. Leveraging multiple datasets for deep leaf counting

    OpenAIRE

    Dobrescu, Andrei; Giuffrida, Mario Valerio; Tsaftaris, Sotirios A

    2017-01-01

    The number of leaves a plant has is one of the key traits (phenotypes) describing its development and growth. Here, we propose an automated, deep learning based approach for counting leaves in model rosette plants. While state-of-the-art results on leaf counting with deep learning methods have recently been reported, they obtain the count as a result of leaf segmentation and thus require per-leaf (instance) segmentation to train the models (a rather strong annotation). Instead, our method tre...

  18. Diffusion archeology for diffusion progression history reconstruction

    OpenAIRE

    Sefer, Emre; Kingsford, Carl

    2015-01-01

    Diffusion through graphs can be used to model many real-world processes, such as the spread of diseases, social network memes, computer viruses, or water contaminants. Often, a real-world diffusion cannot be directly observed while it is occurring — perhaps it is not noticed until some time has passed, continuous monitoring is too costly, or privacy concerns limit data access. This leads to the need to reconstruct how the present state of the diffusion came to be from partial d...

  19. Leaf sequencing algorithms for segmented multileaf collimation

    International Nuclear Information System (INIS)

    Kamath, Srijit; Sahni, Sartaj; Li, Jonathan; Palta, Jatinder; Ranka, Sanjay

    2003-01-01

    The delivery of intensity-modulated radiation therapy (IMRT) with a multileaf collimator (MLC) requires the conversion of a radiation fluence map into a leaf sequence file that controls the movement of the MLC during radiation delivery. It is imperative that the fluence map delivered using the leaf sequence file is as close as possible to the fluence map generated by the dose optimization algorithm, while satisfying hardware constraints of the delivery system. Optimization of the leaf sequencing algorithm has been the subject of several recent investigations. In this work, we present a systematic study of the optimization of leaf sequencing algorithms for segmental multileaf collimator beam delivery and provide rigorous mathematical proofs of optimized leaf sequence settings in terms of monitor unit (MU) efficiency under most common leaf movement constraints that include minimum leaf separation constraint and leaf interdigitation constraint. Our analytical analysis shows that leaf sequencing based on unidirectional movement of the MLC leaves is as MU efficient as bidirectional movement of the MLC leaves

  20. Leaf sequencing algorithms for segmented multileaf collimation

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, Srijit [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States); Sahni, Sartaj [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States); Li, Jonathan [Department of Radiation Oncology, University of Florida, Gainesville, FL (United States); Palta, Jatinder [Department of Radiation Oncology, University of Florida, Gainesville, FL (United States); Ranka, Sanjay [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States)

    2003-02-07

    The delivery of intensity-modulated radiation therapy (IMRT) with a multileaf collimator (MLC) requires the conversion of a radiation fluence map into a leaf sequence file that controls the movement of the MLC during radiation delivery. It is imperative that the fluence map delivered using the leaf sequence file is as close as possible to the fluence map generated by the dose optimization algorithm, while satisfying hardware constraints of the delivery system. Optimization of the leaf sequencing algorithm has been the subject of several recent investigations. In this work, we present a systematic study of the optimization of leaf sequencing algorithms for segmental multileaf collimator beam delivery and provide rigorous mathematical proofs of optimized leaf sequence settings in terms of monitor unit (MU) efficiency under most common leaf movement constraints that include minimum leaf separation constraint and leaf interdigitation constraint. Our analytical analysis shows that leaf sequencing based on unidirectional movement of the MLC leaves is as MU efficient as bidirectional movement of the MLC leaves.

  1. The enigma of effective pathlength for 18O enrichment in leaf water of conifers

    Science.gov (United States)

    Roden, J. S.; Kahmen, A.; Buchmann, N. C.; Siegwolf, R. T.

    2013-12-01

    The stable isotopes of oxygen (δ18O) in tree ring cellulose provide valuable proxy information about past environments and climate. Mechanistic models have been used to clarify the important drivers of isotope fractionation and help interpret δ18O variation in tree rings. A critical component to these models is an estimate of leaf water enrichment. However, standard models seldom accurately predict 18O enrichment in conifer needles and Péclet corrections often require effective pathlengths (L) that seem unreasonable from the perspective of needle morphology (>0.5 m). To analyze the potential role of path length on the Péclet effect in conifers we carried out experiments in controlled environment chambers. We exposed seedlings of six species of conifer (Abies alba, Larix decidua, Picea abies, Pinus cembra, P. sylvestris, Taxus bacata), that differ in needle morphology, to four different vapor pressure deficits (VPD), in order to modify transpiration rates (E) and leaf water 18O enrichment. Environmental and δ18O data (leaf, stem and chamber water vapor) were collected to parameterize leaf water models. Cross-sections of needles were sampled for an analysis of needle anatomy. Conifer needles have a single strand of vascular tissue making pathlength determinations through anatomical assessments possible. The six species differed in mesophyll distance (measured from endodermis to epidermis) and cell number, with Pinus and Picea species having the shortest distance and Abies and Taxus the longest (flat needle morphology). Other anatomical measures (transfusion distance, cell size etc.) did not differ significantly. A suberized strip was apparent in the endodermis of all species except Taxus and Abies. Conifer needles have a large proportion (from 0.2 to 0.4) of needle cross-sectional area in vascular tissues that may not be subject to evaporative enrichment. As expected, leaf water δ18O and E responded strongly to VPD and standard models (Craig

  2. Effect of Addition of Moringa Leaf By-Product (Leaf-Waste) on ...

    African Journals Online (AJOL)

    The effects of incorporation of Moringa leaf fibre (a by-product of leaf processing which contains 24% Crude Fibre by dry weight at 0, 5 and 10 % substitution of wheat flour in cookies was investigated. Three products containing wheat flour: Moringa leaf fibre ratios of 100:0, 95:5, and 90:10 respectively were prepared, and a ...

  3. Specific leaf area estimation from leaf and canopy reflectance through optimization and validation of vegetation indices

    NARCIS (Netherlands)

    Ali, A.M.; Darvishzadeh, R.; Skidmore, A.K.; van Duren, I.C.

    2017-01-01

    Specific leaf area (SLA), which is defined as the leaf area per unit of dry leaf mass is an important component when assessing functional diversity and plays a key role in ecosystem modeling, linking plant carbon and water cycles as well as quantifying plant physiological processes. However, studies

  4. Leaf size and leaf display of thirty-eight tropical tree species

    NARCIS (Netherlands)

    Poorter, L.; Rozendaal, D.M.A.

    2008-01-01

    Trees forage for light through optimal leaf display. Effective leaf display is determined by metamer traits (i.e., the internode, petiole, and corresponding leaf), and thus these traits strongly co-determine carbon gain and as a result competitive advantage in a light-limited environment. We

  5. Spatially Different Tissue-Scale Diffusivity Shapes ANGUSTIFOLIA3 Gradient in Growing Leaves.

    Science.gov (United States)

    Kawade, Kensuke; Tanimoto, Hirokazu; Horiguchi, Gorou; Tsukaya, Hirokazu

    2017-09-05

    The spatial gradient of signaling molecules is pivotal for establishing developmental patterns of multicellular organisms. It has long been proposed that these gradients could arise from the pure diffusion process of signaling molecules between cells, but whether this simplest mechanism establishes the formation of the tissue-scale gradient remains unclear. Plasmodesmata are unique channel structures in plants that connect neighboring cells for molecular transport. In this study, we measured cellular- and tissue-scale kinetics of molecular transport through plasmodesmata in Arabidopsis thaliana developing leaf primordia by fluorescence recovery assays. These trans-scale measurements revealed biophysical properties of diffusive molecular transport through plasmodesmata and revealed that the tissue-scale diffusivity, but not the cellular-scale diffusivity, is spatially different along the leaf proximal-to-distal axis. We found that the gradient in cell size along the developmental axis underlies this spatially different tissue-scale diffusivity. We then asked how this diffusion-based framework functions in establishing a signaling gradient of endogenous molecules. ANGUSTIFOLIA3 (AN3) is a transcriptional co-activator, and as we have shown here, it forms a long-range signaling gradient along the leaf proximal-to-distal axis to determine a cell-proliferation domain. By genetically engineering AN3 mobility, we assessed each contribution of cell-to-cell movement and tissue growth to the distribution of the AN3 gradient. We constructed a diffusion-based theoretical model using these quantitative data to analyze the AN3 gradient formation and demonstrated that it could be achieved solely by the diffusive molecular transport in a growing tissue. Our results indicate that the spatially different tissue-scale diffusivity is a core mechanism for AN3 gradient formation. This provides evidence that the pure diffusion process establishes the formation of the long-range signaling

  6. Leaf gas exchange of understory spruce-fir saplings in relict cloud forests, southern Appalachian Mountains, USA

    Energy Technology Data Exchange (ETDEWEB)

    Reinhardt, K.; Smith, W.K. [Wake Forest Univ., Winston-Salem, NC (United States). Dept. of Biology

    2008-01-15

    Global climate change is expected to increase regional cloud ceiling levels in many mountainous forested areas of the world. This study investigated environmental influences on the gas exchange physiology of understory red spruce and Fraser fir trees at 2 sites in the Appalachian mountains. The study hypothesized that the humid, cloudy environment would influence the photosynthetic performance of the trees, and that the species would adapt to low, diffuse light. The study also predicted that leaf conductance to carbon dioxide (CO{sub 2}) would be high as a result of low leaf-to-air-vapour pressure deficit (LAVD). The study demonstrated that leaf conductance decreased exponentially as LAVD increased. Predawn leaf water potentials remained stable, while late afternoon values declined. It was concluded that leaf gas exchange was correlated with the response of leaf conductance and LAVD. The cloudy, humid environment strongly influenced tree leaf gas exchange and water relations. It was suggested that further research is needed to investigate cloud impacts on carbon gain and water relations. 72 refs., 1 tab., 8 figs.

  7. Growth and wall-transpiration control of nonlinear unsteady Görtler vortices forced by free-stream vortical disturbances

    Science.gov (United States)

    Marensi, Elena; Ricco, Pierre

    2017-11-01

    The generation, nonlinear evolution, and wall-transpiration control of unsteady Görtler vortices in an incompressible boundary layer over a concave plate is studied theoretically and numerically. Görtler rolls are initiated and driven by free-stream vortical perturbations of which only the low-frequency components are considered because they penetrate the most into the boundary layer. The formation and development of the disturbances are governed by the nonlinear unsteady boundary-region equations with the centrifugal force included. These equations are subject to appropriate initial and outer boundary conditions, which account for the influence of the upstream and free-stream forcing in a rigorous and mutually consistent manner. Numerical solutions show that the stabilizing effect on nonlinearity, which also occurs in flat-plate boundary layers, is significantly enhanced in the presence of centrifugal forces. Sufficiently downstream, the nonlinear vortices excited at different free-stream turbulence intensities Tu saturate at the same level, proving that the initial amplitude of the forcing becomes unimportant. At low Tu, the disturbance exhibits a quasi-exponential growth with the growth rate being intensified for more curved plates and for lower frequencies. At higher Tu, in the typical range of turbomachinery applications, the Görtler vortices do not undergo a modal stage as nonlinearity saturates rapidly, and the wall curvature does not affect the boundary-layer response. Good quantitative agreement with data from direct numerical simulations and experiments is obtained. Steady spanwise-uniform and spanwise-modulated zero-mass-flow-rate wall transpiration is shown to attenuate the growth of the Görtler vortices significantly. A novel modified version of the Fukagata-Iwamoto-Kasagi identity, used for the first time to study a transitional flow, reveals which terms in the streamwise momentum balance are mostly affected by the wall transpiration, thus

  8. 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.

  9. 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.

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

    Directory of Open Access Journals (Sweden)

    Maria Aparecida José de Oliveira

    2002-03-01

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

  12. Leaf water enrichment of stable water isotopes (δ18O and δD) in a mature oil palm plantation in Jambi province, Indonesia.

    Science.gov (United States)

    Bonazza, Mattia; Tjoa, Aiyen; Knohl, Alexander

    2017-04-01

    During the last few decades, Indonesia experienced rapid and large scale land-use change towards intensively managed crops, one of them is oil palm. This transition results in warmer and dryer conditions in microclimate. The impacts on the hydrological cycle and on water-use by plants are, however, not yet completely clear. Water stable isotopes are useful tracers of the hydrological processes and can provide means to partition evapotranspiration into evaporation and transpiration. A key parameter, however, is the enrichment of water stable isotope in plant tissue such as leaves that can provide estimates on the isotopic composition of transpiration. Here we present the results of a field campaign conducted in a mature oil palm plantation in Jambi province, Indonesia. We combined continuous measurements of water vapor isotopic composition and mixing ratio with isotopic analysis of water stored in different pools like oil palm leaves, epiphytes, trunk organic matter and soil collected over a three days period. Leaf enrichment varied from -2 ‰ to 10 ‰ relative to source (ground) water. The temporal variability followed Craig and Gordon model predictions for leaf water enrichment. An improved agreement was reached after considering the Péclet effect with an appropriate value of the characteristic length (L). Measured stomatal conductance (gs) on two different sets of leaves (top and bottom canopy) was mainly controlled by radiation (photosynthetically active radiation) and vapor pressure deficit. We assume that this control could be explained in conditions where soil water content is not representing a limiting factor. Understanding leaf water enrichment provides one step towards partitioning ET.

  13. Increasing Leaf Vein Density via Mutagenesis in Rice Results in an Enhanced Rate of Photosynthesis, Smaller Cell Sizes and Can Reduce Interveinal Mesophyll Cell Number

    Directory of Open Access Journals (Sweden)

    Aryo B. Feldman

    2017-11-01

    Full Text Available Improvements to leaf photosynthetic rates of crops can be achieved by targeted manipulation of individual component processes, such as the activity and properties of RuBisCO or photoprotection. This study shows that simple forward genetic screens of mutant populations can also be used to rapidly generate photosynthesis variants that are useful for breeding. Increasing leaf vein density (concentration of vascular tissue per unit leaf area has important implications for plant hydraulic properties and assimilate transport. It was an important step to improving photosynthetic rates in the evolution of both C3 and C4 species and is a foundation or prerequisite trait for C4 engineering in crops like rice (Oryza sativa. A previous high throughput screen identified five mutant rice lines (cv. IR64 with increased vein densities and associated narrower leaf widths (Feldman et al., 2014. Here, these high vein density rice variants were analyzed for properties related to photosynthesis. Two lines were identified as having significantly reduced mesophyll to bundle sheath cell number ratios. All five lines had 20% higher light saturated photosynthetic capacity per unit leaf area, higher maximum carboxylation rates, dark respiration rates and electron transport capacities. This was associated with no significant differences in leaf thickness, stomatal conductance or CO2 compensation point between mutants and the wild-type. The enhanced photosynthetic rate in these lines may be a result of increased RuBisCO and electron transport component amount and/or activity and/or enhanced transport of photoassimilates. We conclude that high vein density (associated with altered mesophyll cell length and number is a trait that may confer increased photosynthetic efficiency without increased transpiration.

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

    Directory of Open Access Journals (Sweden)

    Manoj Kulkarni

    2017-12-01

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

  15. 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.

  16. 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

  17. 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

  18. 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).

  19. Spin-diffusions and diffusive molecular dynamics

    Science.gov (United States)

    Farmer, Brittan; Luskin, Mitchell; Plecháč, Petr; Simpson, Gideon

    2017-12-01

    Metastable configurations in condensed matter typically fluctuate about local energy minima at the femtosecond time scale before transitioning between local minima after nanoseconds or microseconds. This vast scale separation limits the applicability of classical molecular dynamics (MD) methods and has spurned the development of a host of approximate algorithms. One recently proposed method is diffusive MD which aims at integrating a system of ordinary differential equations describing the likelihood of occupancy by one of two species, in the case of a binary alloy, while quasistatically evolving the locations of the atoms. While diffusive MD has shown itself to be efficient and provide agreement with observations, it is fundamentally a model, with unclear connections to classical MD. In this work, we formulate a spin-diffusion stochastic process and show how it can be connected to diffusive MD. The spin-diffusion model couples a classical overdamped Langevin equation to a kinetic Monte Carlo model for exchange amongst the species of a binary alloy. Under suitable assumptions and approximations, spin-diffusion can be shown to lead to diffusive MD type models. The key assumptions and approximations include a well-defined time scale separation, a choice of spin-exchange rates, a low temperature approximation, and a mean field type approximation. We derive several models from different assumptions and show their relationship to diffusive MD. Differences and similarities amongst the models are explored in a simple test problem.

  20. Leaf cuticles as mediators of environmental influences: new developments in the use of isolated cuticles

    International Nuclear Information System (INIS)

    Scherbatskoy, T.

    1994-01-01

    Isolated leaf cuticles have been used in our research to characterize trans-cuticular ion diffusion rates under various environmental treatments and to measure cuticular attenuation of solar radiation. These studies have been conducted to understand better the role of the leaf cuticle as a protective barrier against potential environmental stressors including acid rain, ozone and ultraviolet radiation. These studies provide examples of a variety of current research uses for isolated leaf cuticles. Ion permeability coefficients and exchange rates in isolated cuticles of Acer, Prunus and Citrus species have been studied using several experimental approaches, including measurement of adsorption kinetics, electrical potential and conductance, and perfusion rates. Measured electrical (diffusion) potentials under KCl gradients across isolated cuticles are positive, indicating greater cation permeability. Electrical potentials (and permeability coefficients) vary with ionic strength and pH, and affect the driving force for ion diffusion through cuticles. Ion permeability in cuticles of Prunus serotina foliage was affected by experimental exposure to ozone and ultraviolet treatments. These studies indicate that cuticle permeability properties can be significantly altered by environmental factors. These and related studies on the ion exchange kinetics of Acer saccharum leaf cuticles suggest that foliar ''leaching'' is dominated by cuticle surface exchange mechanisms, with the magnitude of cuticular ion permeation being relatively small. In working with various hardwood species, we observed that the success rate for cuticle isolation varies with tree species and time of year. Scanning electron micrographs of inner cuticle surfaces indicate that the effects of enzymatic digestion could vary with exposure time, possibly affecting transport properties of isolated cuticles. Experimental work to test this in Citrus, however, showed no significant effect of isolation time on

  1. Photosynthetic capacity is negatively correlated with the concentration of leaf phenolic compounds across a range of different species.

    Science.gov (United States)

    Sumbele, Sally; Fotelli, Mariangela N; Nikolopoulos, Dimosthenis; Tooulakou, Georgia; Liakoura, Vally; Liakopoulos, Georgios; Bresta, Panagiota; Dotsika, Elissavet; Adams, Mark A; Karabourniotis, George

    2012-01-01

    Phenolic compounds are the most commonly studied of all secondary metabolites because of their significant protective-defensive roles and their significant concentration in plant tissues. However, there has been little study on relationships between gas exchange parameters and the concentration of leaf phenolic compounds (total phenolics (TP) and condensed tannins (CT)) across a range of species. Therefore, we addressed the question: is there any correlation between photosynthetic capacity (A(max)) and TP and CT across species from different ecosystems in different continents? A plethora of functional and structural parameters were measured in 49 plant species following different growth strategies from five sampling sites located in Greece and Australia. The relationships between several leaf traits were analysed by means of regression and principal component analysis. The results revealed a negative relationship between TP and CT and A(max) among the different plant species, growth strategies and sampling sites, irrespective of expression (with respect to mass, area or nitrogen content). Principal component analysis showed that high concentrations of TP and CT are associated with thick, dense leaves with low nitrogen. This leaf type is characterized by low growth, A(max) and transpiration rates, and is common in environments with low water and nutrient availability, high temperatures and high light intensities. Therefore, the high TP and CT in such leaves are compatible with the protective and defensive functions ascribed to them. Our results indicate a functional integration between carbon gain and the concentration of leaf phenolic compounds that reflects the trade-off between growth and defence/protection demands, depending on the growth strategy adopted by each species.

  2. Leaf anatomical traits of non-arboreal savanna species along a gradient of tree encroachment

    Directory of Open Access Journals (Sweden)

    Luiz Felipe Souza Pinheiro

    2017-10-01

    Full Text Available ABSTRACT In the Brazilian savanna (Cerrado of Brazil, fire suppression has transformed typical savanna formations (TS into forested savanna (FS due to the phenomenon of encroachment. Under encroachment, non-arboreal plants begin to receive less light due to greater tree density and canopy closure. Here we aim to evaluate if leaf anatomical traits of non-arboreal species differ according to the degree of tree encroachment at the Assis Ecological Station - São Paulo, Brazil. To this end, we evaluated leaf tissue thickness and specific leaf area (SLA in representative non-arboreal species occurring along a gradient of tree encroachment. Leaves of TS species showed a trend towards xeromorphism, with traits reported to facilitate survival under high luminosity, such as thick leaves, thick epidermis and mesophyll, and low SLA. In contrast, FS species exhibited mesomorphic leaves, with thin mesophyll and high SLA, which are able to capture diffuse light in denser environments. Thus, non-arboreal understory species with mesomorphic leaf traits should be favored in environments with denser vegetation in contrast to typical savanna species. The results suggest that typical non-arboreal savanna species would not survive under tree encroachment due to the low competitiveness of their leaf anatomical strategies in shady environments.

  3. Leaf Wetness within a Lily Canopy

    NARCIS (Netherlands)

    Jacobs, A.F.G.; Heusinkveld, B.G.; Klok, E.J.

    2005-01-01

    A wetness duration experiment was carried out within a lily field situated adjacent to coastal dunes in the Netherlands. A within-canopy model was applied to simulate leaf wetness in three layers, with equal leaf area indices, within the canopy. This simulation model is an extension of an existing

  4. 7 CFR 29.3528 - Leaf surface.

    Science.gov (United States)

    2010-01-01

    ... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf...

  5. Estimation of leaf area in tropical maize

    NARCIS (Netherlands)

    Elings, A.

    2000-01-01

    Leaf area development of six tropical maize cultivars grown in 1995 and 1996 in several tropical environments in Mexico (both favourable and moisture-and N-limited) was observed and analysed. First, the validity of a bell-shaped curve describing the area of individual leaves as a function of leaf

  6. Chromosome-damaging effect of betel leaf.

    Science.gov (United States)

    Sadasivan, G; Rani, G; Kumari, C K

    1978-05-01

    The chewing of betel leaf with other ingredients is a widespread addiction in India. The chromosome damaging effect was studied in human leukocyte cultures. There was an increase in the frequency of chromatid aberrations when the le