Responses of seven diverse rice cultivars to water deficits. III. Accumulation of abscisic acid and proline in relation to leaf water-potential and osmotic adjustment

The soil and plant water status of irrigated and unirrigated sorghum [Sorghum bicolor (L.) Moench cv. TX610] and sunflower (Helianthus annuus L. cv. Hysun 30) crops were compared on several days from the late vegetative to the early grain-filling stages of development. Additionally, the stems of plants from the irrigated and unirrigated plots of both species were cut near their base; this caused the plants to quickly dry until the stomata closed. The leaf water potential and leaf osmotic potential were measured when the stomatal resistance reached 6 s cm-� to give the water potential for stomatal closure and to provide osmotic potentials at equal turgor. Carbohydrate and potassium levels of leaves were also monitored. The mean daily minimum leaf water potentials in the irrigated sorghum and sunflower did not decrease below - 1 7 MPa and - 2.0 MPa, respectively, but decreased to - 2.1 MPa in the unirrigated sorghum and -2.6 MPa in the unirrigated sunflower. The osmotic potential at stomatal closure in the rapidly dried plants decreased with increasing leaf water deficit in both sunflower and sorghum: in both species the osmotic potential decreased approximately 0.6 MPa for each megapascal decrease in leaf water potential. The results indicate that both sorghum and sunflower adjusted osmotically in response to water deficits and that adjustment occurred at a rate of at least 0.1 MPa per day. The lowering of osmotic potential persisted less than 9 days after the relief of stress in both sunflower and sorghum. The soluble sugar concentration increased linearly in both sunflower and sorghum with osmotic adjustment: the rate of increase of soluble sugars was significantly greater in sunflower than sorghum. No changes in potassium concentration were observed during osmotic adjustment. The water potential at which the stomata closed varied from - 1.5 to -2.6 MPa in sorghum and - 1.7 to -2.7 MPa in sunflower: the water potential that induced stomatal closure decreased as the osmotic potential decreased. Stomatal closure occurred at a mean turgor of -0-5 MPa in both species: systematic error in the measurement of osmotic potential on frozen and thawed leaf tissue is considered the reason for the low turgor potentials at stomatal closure. The adaxial stomatal closed before the abaxial stomata in the sorghum and unirrigated sunflower but, since the leaf water potential initially fell rapidly and then became stable before the adaxial stomata closed, both the adaxial and abaxial stomata closed at the same leaf water potential.

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Interactions between leaf water potential, stomatal conductance and abscisic acid content of orange trees submitted to drought stress

Brazilian Journal of Plant Physiology ◽

10.1590/s1677-04202004000300005 ◽

2004 ◽

Vol 16 (3) ◽

pp. 155-161 ◽

Cited By ~ 38

Author(s):

Mara de Menezes de Assis Gomes ◽

Ana Maria Magalhães Andrade Lagôa ◽

Camilo Lázaro Medina ◽

Eduardo Caruso Machado ◽

Marcos Antônio Machado

Keyword(s):

Abscisic Acid ◽

Water Stress ◽

Stomatal Conductance ◽

Water Potential ◽

Leaf Water Potential ◽

Acid Content ◽

Stomatal Closure ◽

Leaf Water ◽

Orange Trees ◽

Abscisic Acid Content

Thirty-month-old 'Pêra' orange trees grafted on 'Rangpur' lemon trees grown in 100 L pots were submitted to water stress by the suspension of irrigation. CO2 assimilation (A), transpiration (E) and stomatal conductance (g s) values declined from the seventh day of stress, although the leaf water potential at 6:00 a.m. (psipd) and at 2:00 p.m. (psi2) began to decline from the fifth day of water deficiency. The CO2 intercellular concentration (Ci) of water-stressed plants increased from the seventh day, reaching a maximum concentration on the day of most severe stress. The carboxylation efficiency, as revealed by the ratio A/Ci was low on this day and did not show the same values of non-stressed plants even after ten days of rewatering. After five days of rewatering only psi pd and psi2 were similar to control plants while A, E and g s were still different. When psi2 decreases, there was a trend for increasing abscisic acid (ABA) concentration in the leaves. Similarly, stomatal conductance was found to decrease as a function of decreasing psi2. ABA accumulation and stomatal closure occurred when psi2 was lower than -1.0 MPa. Water stress in 'Pera´ orange trees increased abscisic acid content with consequent stomatal closure and decreased psi2 values.

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Influence of Preconditioning upon the Changes in Leaf Conductance and Leaf Water Potential of Soybean, induced by Chilling, Water Stress and Abscisic Acid

Functional Plant Biology ◽

10.1071/pp9870331 ◽

1987 ◽

Vol 14 (3) ◽

pp. 331 ◽

Cited By ~ 1

Author(s):

D Eamus

Keyword(s):

Abscisic Acid ◽

Water Stress ◽

Water Potential ◽

Leaf Water Potential ◽

Leaf Conductance ◽

Leaf Water

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Osmotic Adjustment in Expanding and Fully Expanded Leaves of Sunflower in Response to Water Deficits

Functional Plant Biology ◽

10.1071/pp9800181 ◽

1980 ◽

Vol 7 (2) ◽

pp. 181 ◽

Cited By ~ 37

Author(s):

MM Jones ◽

NC Turner

Keyword(s):

Water Potential ◽

Leaf Water Potential ◽

Osmotic Adjustment ◽

Osmotic Potential ◽

Leaf Water ◽

Similar Degree ◽

Tissue Water ◽

Predawn Leaf Water Potential ◽

Leaf Osmotic Potential ◽

Osmotic Potentials

Sunflower plants were grown in large volumes of soil and slowly water-stressed by withholding water. The tissue water relationships of leaves at various stages of stress and of leaves of equivalent well watered controls were studied by the pressure chamber technique. Plants were stressed either when leaf 17 was expanding or when it was fully expanded. When expanding leaves reached a moderate level of stress (predawn leaf water potential of -0.9 MPa), the osmotic potentials at full turgor and zero turgor were lower than the control values by 0.1 MPa and 0.2 MPa, respectively. When fully expanded leaves were stressed to a similar degree (predawn leaf water potential of - 1.1 MPa), the osmotic potentials at full turgor and zero turgor were lower than the control values by 0.2 MPa and 0.3 MPa, respectively. The development of more severe stress in the fully expanded leaves was not accompanied by any further osmotic adjustment. However, when the expanding leaves reached a predawn leaf water potential of -2.3 MPa, the values of leaf osmotic potential at full turgor and zero turgor were lower than the values for the well watered plants by 0.4 MPa and 0.6 MPa, respectively. In expanding leaves prestressed to a predawn leaf water potential of -2.3 MPa, the osmotic potential at full turgor was significantly less than the control values for at least 7 days after rewatering. Stress had no effect on the bulk modulus of elasticity. It is concluded that both expanding and fully expanded sunflower leaves show osmotic adjustment.

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Genotypic variation in osmotic adjustment in grain sorghum. I. Development of variation in osmotic adjustment under water-limited conditions

Australian Journal of Agricultural Research ◽

10.1071/ar9910747 ◽

1991 ◽

Vol 42 (5) ◽

pp. 747 ◽

Cited By ~ 15

Author(s):

T Tangpremsri ◽

S Fukai ◽

KS Fischer ◽

RG Henzell

Keyword(s):

Water Potential ◽

Water Deficit ◽

Leaf Water Potential ◽

Osmotic Adjustment ◽

Osmotic Potential ◽

Genotypic Variation ◽

Genetic Material ◽

Covariance Analysis ◽

Leaf Water ◽

The Other

Development of genotypic variation in osmotic adjustment was examined in two glasshouse experiments using two sets of sorghum material. In the first experiment, 47 S2 lines extracted from a randomly mated population were used, whereas in the other, inbred parents and their 15 hybrids were compared. In both experiments, water deficit was induced in two periods, one before anthesis and the other after anthesis for most genotypes. In both experiments osmotic potential at the beginning of the first drying period was similar among genotypes and therefore osmotic potential obtained under water deficit was used for the comparison of osmotic adjustment among genotypes. In the first drying period of both experiments, when stress was milder, about 40% of the variation in osmotic adjustment was accounted for by difference in leaf water potential. When the effect of water potential was removed by covariance analysis, there was significant genotypic variation in osmotic adjustment in the second experiment, but not in the first experiment. On the other hand, in the second drying period, when stress was more severe, the effect of leaf water potential on osmotic adjustment was small. There was significant genotypic variation in osmotic adjustment in both experiments after the water potential effect was removed by covariance analysis. Osmotic adjustment in the second drying period was also negatively correlated with grain sink/source ratio (number of grains/leaf area) in the first set of materials. The comparison of osmotic adjustment among hybrids and their parents showed that, in this particular set of genotypes, the female parents were more important than the male in determining osmotic adjustment of the hybrids. The genotypic variation was associated with performance under water deficit in the field. It is concluded that there is considerable genotypic variation in osmotic adjustment in the genetic material examined. Osmotic adjustment is, however, correlated with water potential and grain sink/source balance, and hence the selection for osmotic adjustment needs to ensure that high value is not due simply to low water potential or small head size.

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Vine water deficit : among the 3 applications of pressure chamber, stem water potential is the most sensitive indicator

OENO One ◽

10.20870/oeno-one.2000.34.4.996 ◽

2000 ◽

Vol 34 (4) ◽

pp. 169

Author(s):

Xavier Choné ◽

Olivier Trégoat ◽

Cornelis Van Leeuwen ◽

Denis Dubourdieu

Keyword(s):

Water Potential ◽

Water Deficit ◽

Leaf Water Potential ◽

Water Status ◽

Pressure Chamber ◽

Leaf Water ◽

Sensitive Indicator ◽

Stem Water Potential ◽

Water Deficits ◽

Stem Water

<p style="text-align: justify;">Vine water status is an important factor in grape quality. High tannin and anthocyanin content in red grape berries are related to moderate vine water deficits. Hence, a simple and sensitive indicator is required to determine vine water status and especially water constraint. Pressure chamber allows a quick and easy to practice determination of water status in the vineyard. Three applications of pressure chamber are known: predawn leaf water potential (ΨB), leaf water potential (ΨF) and stem water potential (ΨT). Only ΨB and ΨF are widely used on vines. In this survey ΨB, ΨF, ΨT and transpiration flow were measured on mature leaves to determine non-irrigated vine water status in field grown vines during the growing season. In California as well as in France, stem Ψ was the most discriminating indicator for both moderate and severe water deficits. In every plot surveyed ΨT was much better correlated to leaf transpiration than ΨF. Moreover, ΨT revealed nascent water deficit earlier than ΨB did. Among the three application of pressure chamber, ΨT was the only one to indicate short term water deficit after a rainfall. Hence, ΨT appears to be a useful indicator for grapevine management in both non-irrigated and irrigated vineyards.</p>

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Effect of Water Deficit on Carbon Dioxide Exchange and Leaf Elongation Rate of Panicum maximum Var. trichoglume

Functional Plant Biology ◽

10.1071/pp9760401 ◽

1976 ◽

Vol 3 (3) ◽

pp. 401 ◽

Cited By ~ 16

Author(s):

MM Ludlow ◽

TT Ng

Keyword(s):

Carbon Dioxide ◽

Water Potential ◽

Leaf Water Potential ◽

Net Photosynthesis ◽

Stomatal Resistance ◽

Leaf Water ◽

Carbon Dioxide Exchange ◽

Leaf Elongation ◽

Water Deficits ◽

Water Potentials

The responses of carbon dioxide exchange and leaf elongation of potted P. maximum var. trichoglume plants to water deficits were investigated in controlled environments and outdoors during drying cycles down to -92 bars leaf water potential, The sensitivities of net photosynthesis and leaf elongation to water deficits were similar. The leaf water potentials at which net photosynthesis and elongation ceased (c. -12 bars), and stomatal resistance increased substantially (- 6 bars), were relatively unaffected by nitrogen supply, environmental conditions during growth, and whether plants had previously experienced stress. However, these factors influenced the rate of net photosynthesis, at high leaf water potentials by affecting stomatal resistance and at moderate water potentials by affecting both stomatal and intracellular resistances. Stomata1 resistance was more sensitive than intracellular resistance to water deficits. Dark respiration rate decreased with leaf water potential, and was higher in plants receiving additional nitrogen. At moderate leaf water potentials (-7 to -9 bars), net photosynthesis of this C4 grass exhibited light saturation and rates similar to C3 plants. We suggest that the difference in behaviour of controlled-environment-grown and field-grown plants to water deficits observed with some species is unlikely to be due to differences in the aerial environment, but may result from differences in the rate at which stress develops. The ecological significance and evolution of the C4 syndrome are discussed briefly.

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Partitioning of [14C]Glucose Into Sorbitol and Other Carbohydrates in Apple Under Water Stress

Functional Plant Biology ◽

10.1071/pp9960245 ◽

1996 ◽

Vol 23 (3) ◽

pp. 245 ◽

Cited By ~ 21

Author(s):

Z Wang ◽

B Quebedeaux ◽

GW Stutte

Keyword(s):

Water Stress ◽

Water Potential ◽

Leaf Water Potential ◽

Malus Domestica ◽

Osmotic Adjustment ◽

Leaf Water ◽

Soluble Carbohydrates ◽

Malus Domestica Borkh ◽

Apple Leaves ◽

Mature Apple

Sorbitol plays an important role in osmotic adjustment in mature apple leaves under water stress. This study was conducted to determine whether water stress increases the conversion of glucose to sorbitol in mature apple leaves. A solution of [14C]glucose or [14C]sorbitol was introduced into the cut end of detached apple (Malus domestica Borkh. 'Red Jonathan') shoots which had previously experienced either water stress or no stress. The cut shoots were then placed in sterile deionised water to maintain well-watered conditions or in no water to continue water-stressed conditions. When shoots were labelled with [14C]glucose, 38% of [14C]glucose was recovered as glucose in the leaves at a leaf water potential (Ψw) of -1.0 MPa following a 30-min labelling. The remaining [14C]glucose was converted to sucrose (24%), fructose (21%), and sorbitol (17%). Water stress altered the partitioning of [14C]glucose between sorbitol and sucrose, increasing the ratio from 0.8 at Ψw = -1.0 to 1.7 at Ψw = -3.0 MPa. When shoots were supplied with [14C]sorbitol, <10% of [14C]sorbitol was converted to other soluble carbohydrates. Water stress inhibited the conversion of both [14C]glucose and [14C]sorbitol into starch. The results suggest that sorbitol accumulation may result from the preferential conversion of glucose to sorbitol rather than to sucrose and starch.

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