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

CARVALHO, R. F.; AIDAR, S. T.; AZEVEDO, R. A.; DODD, I. C.; PERES, L. E. P.
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.2%
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.; FAPESP[03/12416-5]; CAPES[2824/05-1]

Validation of a root water uptake model to estimate transpiration constraints

CASAROLI, Derblai; LIER, Quirijn de Jong van; DOURADO NETO, Durval
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.59%
Experimental results obtained from a greenhouse trial with common bean (Phaseolus vulgaris L) plants performed to test model hypotheses regarding the onset of limiting hydraulic conditions and the shape of the transpiration reduction curve in the falling rate phase are presented. According to these hypotheses based on simulations with an upscaled single-root model, the matric flux potential at the onset of limiting hydraulic conditions is as a function of root length density and potential transpiration rate, while the relative transpiration in the falling rate phase equals the relative matric flux potential. Transpiration of bean plants in water stressed pots with four different soils was determined daily by weighing and compared to values obtained from non-stressed pots. This procedure allowed determining the onset of the falling rate phase and corresponding soil hydraulic conditions. At the onset of the falling rate phase, the value of matric flux potential M(I) showed to differ in order of magnitude from the model predicted value for three out of four soils. This difference between model and experiment can be explained by the heterogeneity of the root distribution which is not considered by the model. An empirical factor to deal with this heterogeneity should be included in the model to improve predictions. Comparing the predictions of relative transpiration in the falling rate phase using a linear shape with water content...

Atividade das enzimas redutase do nitrato e glutamina sintetase em cafeeiro arábica.; Activity of the nitrate reductase and glutamine synthetase enzymes in arabic coffee.

Andrade Netto, José Fernandes de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/04/2005 PT
Relevância na Pesquisa
46.24%
O objetivo deste trabalho foi avaliar a atividade das enzimas redutase do nitrato (RN) e glutamina sintetase (GS) em mudas de Coffea arabica L cv Obatã IAC 1669-20 em função dos atributos ecofisiológicos. O experimento foi conduzido em casa de vegetação no Laboratório de Biotecnologia Agrícola do Departamento de Ciências Biológicas da Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo. Para a realização do experimento adotou-se o delineamento inteiramente casualizado com dois tratamentos: T1 (100% de luz) e T2 (50% de luz) e cinco repetições. As determinações das atividades enzimáticas foram feitas às 07:00 h; 12:00 h; 17:00 h e 22:00 h, bem como dos atributos ecofisiológicos: temperatura atmosférica; temperatura foliar; radiação fotossinteticamente ativa; condutância estomática; taxa de fotossíntese líquida; taxa de transpiração e proteína total solúvel. O nível de exposição à luminosidade altera a atividade da redutase do nitrato (RN), cujo valor foi menor nas plantas a pleno sol às 12:00 h e 17:00 h. A saturação lumínica e a maior temperatura foliar em relação ao ambiente, às 12:00 h, diminuiu as trocas gasosas (CO2 e vapor d’água) e a atividade da RN. Ao longo do período luminoso...

Transpiração de plantas e condições hidráulicas do solo; Plant transpiration and soil hydraulic conditions

Casaroli, Derblai
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/05/2008 PT
Relevância na Pesquisa
36.52%
Taxas de transpiração inferiores às taxas potenciais limitam o crescimento e desenvolvimento vegetal e ocorrem em solos que apresentam condições hidráulicas inadequadas para a manutenção do fluxo de água requerido em direção às raízes de uma planta. A pesquisa que resultou nesta tese teve como objetivos: estimar em quais condições hidráulicas se inicia a redução da taxa de transpiração, em termos de potencial de fluxo matricial (Mcrit), teor de água ( ?crit), potencial matricial (hcrit) e condutividade hidráulica (Kcrit), para diferentes solos e condições atmosféricas; demonstrar experimentalmente que Mcrit é independente do tipo de solo e influenciado apenas pelas características radiculares e demanda atmosférica, ao contrário de ?crit, hcrit e Kcrit; comparar valores de Mcrit obtidos nos experimentos com respectivos valores de Mcrit estimados por um modelo de extração de água do solo por raízes, para uma mesma densidade radicular; propor uma alternativa para a estimativa de ?crit no solo, baseada na interrelação entre M, ? e h. O presente estudo conteve dois experimentos conduzidos em ambiente protegido, com plantas de feijão (Phaseolus vulgaris L.) cultivadas em vasos. O delineamento experimental utilizado...

Photosynthetic responses and proline content of mature and young leaves of sunflower plants under water deficit

Cechin, I.; Rossi, S. C.; Oliveira, V. C.; Fumis, T. F.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 143-146
ENG
Relevância na Pesquisa
46.21%
In mature and young leaves of sunflower (Helianthus annuus L. cv. Catissol-01) plants grown in the greenhouse, photosynthetic rate, stomatal conductance, and transpiration rate declined during water stress independently of leaf age and recovered after 24-h rehydration. The intercellular CO 2 concentration, chlorophyll (Chl) content, and photochemical activity were not affected by water stress. However, non-photochemical quenching increased in mature stressed leaves. Rehydration recovered the levels of non-photochemical quenching and increased the F v/F m in young leaves. Drought did not alter the total Chl content. However, the accumulation of proline under drought was dependent on leaf age: higher content of proline was found in young leaves. After 24 h of rehydration the content of proline returned to the same contents as in control plants.

Effect of relative air humidity on the stomatal functionality in fully developed leaves

Fanourakis, D.; Matkaris, N.; Heuvelink, E.; Carvalho, S. M. P.
Fonte: Universidade Católica Portuguesa Publicador: Universidade Católica Portuguesa
Tipo: Artigo de Revista Científica
Publicado em //2010 ENG
Relevância na Pesquisa
46.17%
Several studies have shown that stomata developed under long-term high relative air humidity (RH ≥85%) are malfunctional, resulting in a poor control of water loss. Yet, little is known about the dynamics of stomatal adaptation to moderate RH, and the possibilities to improve or reverse the destabilized stomatal responsiveness. In this study, a reciprocal transfer experiment was conducted in climate chambers using Rosa hybrida ‘Prophyta’, grown at moderate RH (60%) or at high RH (90%). The adaptation of fully developed leaves to the new RH environment was assessed at day 0, 4, 8 and 12 after plant transfer by measuring the transpiration rate in detached leaves. Stomata fully developed at high RH had a lower closing capacity in response to a decrease in leaf Relative Water Content (RWC) (i.e. water loss was considerably high at RWC below 20%, whereas in moderate RH stomata the water loss almost ceased at 57% RWC). Furthermore, stomata developed at high RH did not become functional after 12 days of cultivation at moderate RH. Similarly, stomata developed at moderate RH and transferred to high RH for a 12 day period did not loose their ability to close in response to desiccation. This indicates that stomatal functionality is determined during leaf development...

Water use, transpiration, and crop coefficients for olives (cv. Cordovil), grown in orchards in Southern Portugal

Ramos, Alice; Santos, Francisco Lúcio
Fonte: Biosystems Engineering Publicador: Biosystems Engineering
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.61%
To improve the scheduling of irrigation for low-density olive trees (Olea europaea L.) grown in a typical Mediterranean environment of Southern Portugal, and to clarify the mechanisms of water uptake by trees, transpiration, soil water status and stomatal response to water deficit were measured in an olive orchard. Olive trees of cv. Cordovil were subject to three irrigation treatments: full-rate irrigation, sustained deficit irrigation (SDI) providing for approximately 60% of water applied at full-rate irrigation, and a regulated deficit irrigation (RDI) with water applied at periods during three critical phases: before-flowering, at beginning of pit-hardening, before crop-harvesting to replenish soil moisture to field capacity. There was also a dry-farming treatment. Trees responded differently to summer rainfall and irrigation water: full-rate irrigation, which received 880 mm of irrigation and 240 mm of rainfall, used 704 mm for transpiration; SDI, which received the same amount of rainfall and 448 mm of irrigation water, used 745 mm of water for transpiration; RDI, which received 69 mm of irrigation water and 240 mm of rainfall, used 638 mm of water for tree transpiration; dry-farming, which received no irrigation, benefited from 240 mm of summer and early autumn rain and used 404 mm of water for transpiration. The results support the hypothesis that trees under RDI and dry-farming satisfy most of their early atmospheric evaporative demand by extracting water from outside of the area wetted by drip irrigation. Scaled-up orchard transpiration was used to define orchard crop and water stress coefficients. With full-rate irrigation and SDI the results showed that during summer droughts olive trees slow down their physiological mechanisms to conserve water...

Water use and response of a dry-farmed olive orchard recently converted to irrigation

Santos, Francisco Lúcio; Valverde, Pedro; Ramos, Alice; Reis, João; Castanheira, Nádia
Fonte: Biosystems Engineering Publicador: Biosystems Engineering
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.52%
Experimental results obtained in Southern Portugal from a dry-farmed mature olive tree orchard recently converted to drip irrigation are described. Water use and response to two irrigation management practices by olive trees was monitored with sap flow compensation heat pulse sensors, ‘Watermark’ granular matrix block sensors and a capacitance probe. The 80-plus-year-old mature olive tree orchard planted on a 12 m by 12 m spacing layout was converted in 2005 from dry-farming to drip irrigation and subjected to two water treatments: trees irrigated daily to supply for crop water demand and trees irrigated before-flowering, during pit-hardening and before crop-harvesting. Sap flow sensors were implanted in sample trees at three different positions around the trunk and measurements were taken at 30 min intervals during 4 months, from April to mid-August of 2005. Tree transpiration rates were estimated as average of sap flow rates. When trees were fully irrigated, the observed differences in daily sap flow rate amplitude were explained by the natural trees difference in canopy cover, plant height and conductance of water vapour sites. However, when deficit irrigation was prescribed and, when the trees stopped being irrigated, they gradually lost their ability to adequately respond to the evaporative demands of the day...

Salinity-induced effects on transpiration rate, stomatal conductance and leaf area of three olive (Olea europaea L.) varieties

Coelho, Renato; Moitas, Mário; Rato, Ana; Vaz, Margarida
Fonte: Actas XII Congresso Luso-Espanhol de Fisiologia Vegetal, Lisboa Publicador: Actas XII Congresso Luso-Espanhol de Fisiologia Vegetal, Lisboa
Tipo: Aula
ENG
Relevância na Pesquisa
56.55%
Transpiration of two year-old olive trees of three different varieties, Arbequina, Cobrançosa and Galega (18 trees per variety), irrigated with three levels of salt (0, 80 or 200 mM NaCl) for about 90 days, was measured by a gravimetric method. To determine leaf area, each tree was photographed from the side against a white background and the total area of each projected image was determined with ImageJ software. To calibrate these area determinations, one tree of each variety was subsequently stripped of all its leaves and its total leaf area was accurately measured. A correlation was then obtained between the area on the photograph of this particular tree and the total area of the detached leaves of the same tree. Using the leaf area determined by this procedure, transpiration rates of the trees could be calculated. Knowing leaf and air temperatures and RH, it was possible to determine the difference in molar fraction of water between the leaf and the air. Using this and the values of the transpiration rate, stomatal conductance could be calculated (gs calc) and compared with the conductance measured on the same trees with a porometer (gs). Actual leaf area of a plant was 1,40 (Arbequina), 1,42 (Cobrançosa) or 1,24 (Galega) times the area measured with ImageJ on the photograph of the same plant. Leaf area of the trees...

Transpiration rate response to water deficit during vegetative and reproductive phases of upland rice cultivars

Heinemann,Alexandre Bryan; Stone,Luís Fernando; Fageria,Nand Kumar
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2011 EN
Relevância na Pesquisa
56.29%
Water deficit is one of the most important abiotic stress limiting upland rice yield in the "Cerrado" region of Brazil. Selecting drought tolerant cultivars is an important strategy to overcome this constraint. Two greenhouse experiments were conducted at Santo Antônio de Goiás, state of Goiás, Brazil, to compare the response of normalized transpiration rate (NTR) of three modern (BRS Primavera, BRSMG Curinga and BRS Soberana) and one traditional (Douradão) upland rice cultivars to soil water deficit during the vegetative and reproductive growth stages. This information will support breeding strategies to improve rice yield in a drought-prone target population environments (TPE) in Brazil. NTR and the total fraction of transpirable soil water (FTSW) were calculated, plotted and adjusted according to a sigmoid non-linear model. The p factor, defined as the fraction of available soil water that can be removed from the root zone before water deficit occurs, was calculated by assuming that it occurs when NTR is equal to 0.95. Modern cultivars had a higher value of p for the reproductive phase than for the vegetative phase. In addition, these cultivars are better adapted to express their potential yield in regions with low intensity and occurrence of water stress and the traditional cultivar is enable to better support adverse conditions of water stress. It can be concluded that there is need to precisely characterize drought patterns in TPEs. This information can focus the breeding program to improve drought tolerance in modern upland rice cultivars.

Transpiration Rate. An Important Factor Controlling the Sucrose Content of the Guard Cell Apoplast of Broad Bean1

Outlaw, William H.; De Vlieghere-He, Xiaoyi
Fonte: American Society of Plant Physiologists Publicador: American Society of Plant Physiologists
Tipo: Artigo de Revista Científica
Publicado em /08/2001 EN
Relevância na Pesquisa
46.49%
Evaporation of water from the guard cell wall concentrates apoplastic solutes. We hypothesize that this phenomenon provides two mechanisms for responding to high transpiration rates. First, apoplastic abscisic acid is concentrated in the guard cell wall. Second, by accumulating in the guard cell wall, apoplastic sucrose (Suc) provides a direct osmotic feedback to guard cells. As a means of testing this second hypothesized mechanism, the guard cell Suc contents at a higher transpiration rate (60% relative humidity [RH]) were compared with those at a lower transpiration rate (90% RH) in broad bean (Vicia faba), an apoplastic phloem loader. In control plants (constant 60% RH), the guard cell apoplast Suc content increased from 97 ± 81 femtomol (fmol) guard cell pair−1 to 701 ± 142 fmol guard cell pair−1 between daybreak and midday. This increase is equivalent to approximately 150 mm external, which is sufficient to decrease stomatal aperture size. In plants that were shifted to 90% RH before daybreak, the guard cell apoplast Suc content did not increase during the day. In accordance, in plants that were shifted to 90% RH at midday, the guard cell apoplast Suc content declined to the daybreak value. Under all conditions, the guard cell symplast Suc content increased during the photoperiod...

Partial phenotypic reversion of ABA-deficient flacca tomato (Solanum lycopersicum) scions by a wild-type rootstock: normalizing shoot ethylene relations promotes leaf area but does not diminish whole plant transpiration rate

Dodd, Ian C.; Theobald, Julian C.; Richer, Sarah K.; Davies, William J.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.41%
To evaluate the role of root-synthesized ABA in regulating growth and stomatal behaviour under well-watered conditions, isogenic wild-type (WT) and ABA-deficient flacca (flc) tomato (Solanum lycopersicum) were reciprocally and self-grafted just below the cotyledonary node. Since flc scions had lower leaf water potentials due to higher transpiration rates, a subset of all graft combinations was grown under a shoot misting treatment to minimize differences in shoot water status. Misting did not alter the relative effects of the different graft combinations on leaf area. WT scions had the greatest leaf area and lowest whole plant transpiration rate irrespective of the rootstock, implying that shoot ABA biosynthesis was sufficient to account for a WT shoot phenotype. In WT scions, the rootstock had no effect on detached leaf ethylene evolution or xylem concentrations of ABA or the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC). In flc scions, although the WT rootstock suppressed stomatal conductance of individual leaves, there was no detectable effect on whole plant transpiration rate. However, leaf area of flc/WT (scion/rootstock) plants increased 1.6-fold compared to flc self-grafts. WT rootstocks increased xylem ABA concentration in flc scions (relative to flc self-grafts) up to 3-fold...

Drought, Abscisic Acid and Transpiration Rate Effects on the Regulation of PIP Aquaporin Gene Expression and Abundance in Phaseolus vulgaris Plants

AROCA, RICARDO; FERRANTE, ANTONIO; VERNIERI, PAOLO; CHRISPEELS, MAARTEN J.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Publicado em /12/2006 EN
Relevância na Pesquisa
46.17%
• Background and Aims Drought causes a decline of root hydraulic conductance, which aside from embolisms, is governed ultimately by aquaporins. Multiple factors probably regulate aquaporin expression, abundance and activity in leaf and root tissues during drought; among these are the leaf transpiration rate, leaf water status, abscisic acid (ABA) and soil water content. Here a study is made of how these factors could influence the response of aquaporin to drought.

Control of transpiration by radiation

Pieruschka, Roland; Huber, Gregor; Berry, Joseph A.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.52%
The terrestrial hydrological cycle is strongly influenced by transpiration—water loss through the stomatal pores of leaves. In this report we present studies showing that the energy content of radiation absorbed by the leaf influences stomatal control of transpiration. This observation is at odds with current concepts of how stomata sense and control transpiration, and we suggest an alternative model. Specifically, we argue that the steady-state water potential of the epidermis in the intact leaf is controlled by the difference between the radiation-controlled rate of water vapor production in the leaf interior and the rate of transpiration. Any difference between these two potentially large fluxes is made up by evaporation from (or condensation on) the epidermis, causing its water potential to pivot around this balance point. Previous work established that stomata in isolated epidermal strips respond by opening with increasing (and closing with decreasing) water potential. Thus, stomatal conductance and transpiration rate should increase when there is condensation on (and decrease when there is evaporation from) the epidermis, thus tending to maintain homeostasis of epidermal water potential. We use a model to show that such a mechanism would have control properties similar to those observed with leaves. This hypothesis provides a plausible explanation for the regulation of leaf and canopy transpiration by the radiation load and provides a unique framework for studies of the regulation of stomatal conductance by CO2 and other factors.

Overexpression of Rice NAC Gene SNAC1 Improves Drought and Salt Tolerance by Enhancing Root Development and Reducing Transpiration Rate in Transgenic Cotton

Liu, Guanze; Li, Xuelin; Jin, Shuangxia; Liu, Xuyan; Zhu, Longfu; Nie, Yichun; Zhang, Xianlong
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 28/01/2014 EN
Relevância na Pesquisa
46.34%
The SNAC1 gene belongs to the stress-related NAC superfamily of transcription factors. It was identified from rice and overexpressed in cotton cultivar YZ1 by Agrobacterium tumefaciens-mediated transformation. SNAC1-overexpressing cotton plants showed more vigorous growth, especially in terms of root development, than the wild-type plants in the presence of 250 mM NaCl under hydroponic growth conditions. The content of proline was enhanced but the MDA content was decreased in the transgenic cotton seedlings under drought and salt treatments compared to the wild-type. Furthermore, SNAC1-overexpressing cotton plants also displayed significantly improved tolerance to both drought and salt stresses in the greenhouse. The performances of the SNAC1-overexpressing lines under drought and salt stress were significantly better than those of the wild-type in terms of the boll number. During the drought and salt treatments, the transpiration rate of transgenic plants significantly decreased in comparison to the wild-type, but the photosynthesis rate maintained the same at the flowering stage in the transgenic plants. These results suggested that overexpression of SNAC1 improve more tolerance to drought and salt in cotton through enhanced root development and reduced transpiration rates.

Transpiration rate response to water deficit during vegetative and reproductive phases of upland rice cultivars.

HEINEMANN, A. B.; STONE, L. F.; FAGERIA, N. K.
Fonte: Scientia Agricola, Piracicaba, v. 68, n. 1, p. 24-30, jan./fev. 2011. Publicador: Scientia Agricola, Piracicaba, v. 68, n. 1, p. 24-30, jan./fev. 2011.
Tipo: Artigo em periódico indexado (ALICE)
EN
Relevância na Pesquisa
46.17%
Water deficit is one of the most important abiotic stress limiting upland rice yield in the ?Cerrado? region of Brazil. Selecting drought tolerant cultivars is an important strategy to overcome this constraint. Two greenhouse experiments were conducted at Santo Antônio de Goiás, state of Goiás, Brazil, to compare the response of normalized transpiration rate (NTR) of three modern (BRS Primavera, BRSMG Curinga and BRS Soberana) and one traditional (Douradão) upland rice cultivars to soil water deficit during the vegetative and reproductive growth stages. This information will support breeding strategies to improve rice yield in a drought-prone target population environments (TPE) in Brazil. NTR and the total fraction of transpirable soil water (FTSW) were calculated, plotted and adjusted according to a sigmoid non-linear model. The p factor, defined as the fraction of available soil water that can be removed from the root zone before water deficit occurs, was calculated by assuming that it occurs when NTR is equal to 0.95. Modern cultivars had a higher value of p for the reproductive phase than for the vegetative phase. In addition, these cultivars are better adapted to express their potential yield in regions with low intensity and occurrence of water stress and the traditional cultivar is enable to better support adverse conditions of water stress. It can be concluded that there is need to precisely characterize drought patterns in TPEs. This information can focus the breeding program to improve drought tolerance in modern upland rice cultivars.; 2011

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

Wallach, Rony; Da-Costa, Noam; Raviv, Michael; Moshelion, Menachem
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.53%
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 m2 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.

Non-steady-state, non-uniform transpiration rate and leaf anatomy effects on the progressive stable isotope enrichment of leaf water along monocot leaves

Ogee, Jerome; Cuntz, Matthias Oskar; Peylin, Philippe; Bariac, T
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.2%
This study focuses on the spatial patterns of transpiration-driven water isotope enrichment (Δlw) along monocot leaves. It has been suggested that these spatial patterns are the result of competing effects of advection and (back-)diffusion of water isoto

The multifaceted relationship between leaf water 18 O enrichment and transpiration rate

Cernusak, Lucas; Kahmen , Ansgar
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.17%
This article comments on: Transpiration rate relates to within- and across-species variations in effective path length in a leaf water model of oxygen isotope enrichment

Resposta da taxa de transpiração ao déficit hídrico nas fases vegetativa e reprodutiva de cultivares de arroz de terras altas; Transpiration rate response to water deficit during vegetative and reproductive phases of upland rice cultivars

Heinemann, Alexandre Bryan; Stone, Luís Fernando; Fageria, Nand Kumar
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/02/2011 ENG
Relevância na Pesquisa
56.29%
Water deficit is one of the most important abiotic stress limiting upland rice yield in the "Cerrado" region of Brazil. Selecting drought tolerant cultivars is an important strategy to overcome this constraint. Two greenhouse experiments were conducted at Santo Antônio de Goiás, state of Goiás, Brazil, to compare the response of normalized transpiration rate (NTR) of three modern (BRS Primavera, BRSMG Curinga and BRS Soberana) and one traditional (Douradão) upland rice cultivars to soil water deficit during the vegetative and reproductive growth stages. This information will support breeding strategies to improve rice yield in a drought-prone target population environments (TPE) in Brazil. NTR and the total fraction of transpirable soil water (FTSW) were calculated, plotted and adjusted according to a sigmoid non-linear model. The p factor, defined as the fraction of available soil water that can be removed from the root zone before water deficit occurs, was calculated by assuming that it occurs when NTR is equal to 0.95. Modern cultivars had a higher value of p for the reproductive phase than for the vegetative phase. In addition, these cultivars are better adapted to express their potential yield in regions with low intensity and occurrence of water stress and the traditional cultivar is enable to better support adverse conditions of water stress. It can be concluded that there is need to precisely characterize drought patterns in TPEs. This information can focus the breeding program to improve drought tolerance in modern upland rice cultivars.; A deficiência hídrica é considerada um dos mais importantes estresses abióticos que limitam a produtividade do arroz de terras altas no Cerrado. Uma estratégia para minimizar os efeitos da estiagem durante o período chuvoso na produtividade do arroz de terras altas é o uso de cultivares com mecanismos de tolerância à seca. Foram conduzidos dois experimentos em casa de vegetação em Santo Antônio de Goiás...