Osmotic Adjustment in Water Stressed Grapevine Leaves in Relation to Carbon Assimilation

1993 ◽  
Vol 20 (3) ◽  
pp. 309 ◽  
Author(s):  
ML Rodrigues ◽  
MM Chaves ◽  
R Wendler ◽  
MM David ◽  
WP Quick ◽  
...  
Keyword(s):  
Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Soluble Sugars ◽  
Carbon Assimilation ◽  
Dry Weight ◽  
Leaf Water ◽  
Soluble Carbohydrates ◽  
Water Fraction ◽  
The Difference

The response of grapevine plants to severe water deficit (predawn leaf water potential of - 1.13 MPa), imposed at a rate of about 0.16 MPa day-1 was studied in terms of leaf water relations characteristics, stomatal behaviour and gas exchange. Carbohydrate status of leaves was also analysed in order to assess the contribution of soluble sugars as osmotic solutes during drought. Pressure/volume analysis showed an active osmotic adjustment in water-stressed leaves, which decreased osmotic potential at full turgor by 0.45 MPa and the apoplastic water fraction showed a reduction of 19% as compared to the well- watered plants. Cell wall elasticity was not significantly affected by water stress, and turgor loss point in stressed leaves was reached at lower water potential and relative water content values than in the well-watered controls. Photosynthesis was markedly reduced in water-stressed plants. However, well-watered and water-stressed leaves had similar concentrations of glucose and fructose. The concentrations of sucrose and starch decreased in water-stressed leaves. This accounted for a marked decrease in the ratio of leaf dry weight to area in droughted plants. The changes in concentrations of soluble carbohydrates could not account for the difference in osmotic potential between water-stressed and well-watered leaves.

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

1980 ◽  
Vol 7 (2) ◽  
pp. 181 ◽  
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.

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

1991 ◽  
Vol 42 (5) ◽  
pp. 747 ◽  
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.

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

1996 ◽  
Vol 23 (3) ◽  
pp. 245 ◽  
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.

Osmotic Adjustment of Sorghum and Sunflower Crops in Response to Water Deficits and Its Influence on the Water Potential at Which Stomata Close

1978 ◽  
Vol 5 (5) ◽  
pp. 597 ◽  
Author(s):  
NC Turner ◽  
JE Begg ◽  
ML Tonnet
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Water Deficits ◽  
Rate Of Increase ◽  
Leaf Osmotic Potential ◽  
Response To Water

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.

Comparing plant water relations for wheat with alternative pulse and oilseed crops grown in the semiarid Canadian prairie

2009 ◽  
Vol 89 (5) ◽  
pp. 823-835 ◽  
Author(s):  
H W Cutforth ◽  
S V Angadi ◽  
B G McConkey ◽  
M H Entz ◽  
D Ulrich ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Leaf Water ◽  
Oilseed Crops ◽  
Pulse Crops ◽  
The Mean

Understanding the drought physiology of alternate crops is essential to assess the production risks of new cropping systems. We compared the water relations of dry (field) pea (Pisum sativum L.), chickpea (Cicer arietinum L.), canola (Brassica napus L.) and mustard (Brassica juncea L.) with spring wheat (Triticum aestivum L.) under different moisture availabilities in field trials conducted in 1997 and 1998 at Swift Current, SK. Stress experience and stress responses varied with crop type. In general, there were similarities in drought physiology between the two pulse crops and between the two oilseed crops. The mean predawn leaf water potential of pea was frequently lowest, while the mean midday leaf water potential of wheat was at least -0.40 MPa lower than for any other crop. The crops exhibited different strategies to overcome water stress. Wheat had the lowest osmotic potential at full turgor, except under drought when turgor was lowest for chickpea and wheat; the highest values were observed in Brassica spp. Mean midday pressure potentials were lowest in wheat (and mostly negative, indicating loss of turgor) and highest for the pulse crops. Mean midday pressure potential for canola was positive when well-watered, otherwise it was near 0. Despite lowering osmotic potential, wheat could not maintain positive turgor much of the time at midday. Pulse crops, with the contributions from both osmotic adjustment and cell elasticity, maintained positive turgor over a wider range of water potentials compared with the other crops. With regard to both osmotic adjustment and tissue elasticity, we ranked the crops from high to low ability to adjust to moderate to severe water stress as pulses > wheat > Brassica oilseeds. Key words: Leaf water, osmotic, turgor potentials, wheat, pulse, canola, semiarid prairie

Osmotic Adjustment, Induced by Drought, in Seedlings of Three Eucalyptus Species

1986 ◽  
Vol 13 (5) ◽  
pp. 597 ◽  
Author(s):  
BA Myers ◽  
TF Neales
Keyword(s):  
Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Dry Weight ◽  
Eucalyptus Species ◽  
Plant Water ◽  
Mature Trees ◽  
Mean Values ◽  
Turgor Maintenance ◽  
Plant Water Potential

Osmotic adjustment was observed in pot-grown seedlings of Eucalyptus behriana, E. microcarpa and E. polyanthemos that had been subjected to one and two periods of drought. The osmotic potential of sap expressed from rehydrated leaves was significantly lower in seedlings which had wilted twice (-2.02 � 0.05 MPa) compared with those which had wilted once (-1.86 � 0.05 MPa) and those which had been watered daily (-1.66 � 0.05 MPa). After two drought cycles, seedlings began to wilt at lower mean values of plant water potential (- 3.51 � 0.22 MPa) than those which had not wilted previously (-3.14 � 0.22 MPa). Thus drought-induced osmotic adjustment apparently enhanced turgor maintenance. The ratio of turgid weight to dry weight was slightly, but significantly, smaller in the seedlings subjected to two drought cycles (3.83 � 0.04 MPa) compared with those subjected to one drought cycle (4.05 � 0.04). The osmotic adjustment that was induced by two drought cycles in these seedlings was about one third of the observed seasonal osmotic adjustment in mature trees of E. behriana and E. microcarpa in the field.

Water stress conditioning of corn (Zea mays) in the field and the greenhouse

1985 ◽  
Vol 63 (4) ◽  
pp. 704-710 ◽  
Author(s):  
L. M. Dwyer ◽  
D. W. Stewart
Keyword(s):  
Zea Mays ◽  
Water Stress ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Leaf Water ◽  
Temperature Sensitive ◽  
Pressure Potential ◽  
Response To Water

Leaf water potential, osmotic potential, and leaf conductance were measured on corn (Zea mays L.) under water stress in the field and the greenhouse. Field-grown plants were subjected to several cycles of moderate water stress during vegetative growth, while greenhouse plants were well watered until just before the measurement period began following tasselling. In both the field and the greenhouse, leaf water potential declined at midday. Comparison of leaf water potential and osmotic potential measurements indicated that in both environments, the midday decline in leaf water potential was accompanied by a decline in osmotic potential. Since the decline in osmotic potential was greater than that accounted for by predicted volume changes resulting from normal daily dehydration, it was assumed to indicate osmotic adjustment. Despite these similarities, field-grown plants showed a greater response to water stress. Field plants underwent larger daily changes in leaf water potential and these were accompanied by larger changes in osmotic potential. As a result of this greater osmotic adjustment in the field, conductivity was higher at equivalent leaf water potentials and the critical leaf water potential was lower than in greenhouse-grown plants. In both environments, osmotic adjustment maintained leaf turgor (or pressure potential) in a narrow positive range. Although there was no direct relation between turgor potential and leaf conductivity, we hypothesize that the maintenance of a positive turgor potential during daylight hours is significant for growth since it may allow the moisture- and temperature-sensitive process of leaf expansion to proceed during the warmer daylight hours, even under moderate water stress.

Effects of Osmotica Around the Roots on Water Uptake by Maize Plants

1980 ◽  
Vol 7 (1) ◽  
pp. 27 ◽  
Author(s):  
RA Nulsen ◽  
GW Thurtell
Keyword(s):  
Polyethylene Glycol ◽  
Water Potential ◽  
Nutrient Solution ◽  
Leaf Water Potential ◽  
Flow Rate ◽  
Osmotic Potential ◽  
Leaf Water ◽  
Maize Plants ◽  
The Difference ◽  
Osmotic Potentials

Nutrient solutions with osmotic potentials of -70, -190 and -380 kPa were supplied to maize plants whose roots were enclosed in a pressure chamber. The plants were stressed and then rewatered with the same nutrient solution. Sap flow rate from the detopped root system was measured at 400 kPa applied pressure. The lower was the osmotic potential of the pretreatment solution, the lower was the initial flow rate. Flow rates rapidly decreased to zero and did not recover for up to 90 min. Different responses in leaf water potential of unstressed, intact plants occurred when the nutrient solution bathing the root was replaced by either a more concentrated nutrient solution or a solution of sucrose or polyethylene glycol 6000. For nutrient solution replacement the change in leaf water potential was less than the difference in solution osmotic potentials; for sucrose the difference was greater, and for polyethylene glycol the change was equal to the osmotic potential difference. Osmotic effects observed were due to differential accumulations at different barriers in the root. The zero-flow periods seen during recovery of severely stressed plants may have been due to a decrease in the osmotic potential of the solution external to the plasmalemma of root cortical cells.

scholarly journals Water regime and osmotic adjustment under warming conditions on wheat in the Yaqui Valley, Mexico

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7029
Author(s):  
Leandris Argentel-Martínez ◽  
Jaime Garatuza-Payan ◽  
Enrico A. Yepez ◽  
Tulio Arredondo ◽  
Sergio de los Santos-Villalobos
Keyword(s):  
Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Canopy Temperature ◽  
Potential Gradient ◽  
Temperature Treatment ◽  
Leaf Water ◽  
Wheat Crop ◽  
Yaqui Valley ◽  
Crop Area

An experiment was carried out to evaluate the effect of increased temperature on roots and leaf water and osmotic potential, osmotic adjustment (OA) and transpiration on Triticum durum L. (CIRNO C2008 variety) during growth (seedling growth), tillering and heading phenophases. Wheat was sown under field conditions at the Experimental Technology Transfer Center (CETT-910), as a representative wheat crop area from the Yaqui Valley, Sonora México. Thermal radiators were placed at 1.20 m from the crop canopy. Treatments included warmed plots (2 °C) and ambient canopy temperature with five replicates. Temperature treatment was controlled using a (proportional, integrative, derivative) feedback control system on plots covering a circular area of r = 1.5 m. Results indicated a significant decrease in the osmotic potential of roots and leaves for the warmed plots. Water potential, under warming treatment, also experienced a significant reduction and a potential gradient was observed in both, roots and leaves, while the phenophases were delayed. Such results demonstrate that, under warmer conditions, plants increase water absorption for cooling. Hence, transpiration experienced a significant increase under warming in all phenophases that was related to the low root and leaf water potential. CIRNO C2008 also experienced OA in all phenophases with glycine betaine as the osmolyte with major contribution.

Carbon dioxide enrichment and water stress interaction on growth of two tomato cultivars

1984 ◽  
Vol 102 (3) ◽  
pp. 687-693 ◽  
Author(s):  
Alejandra Paez ◽  
H. Hellmers ◽  
B. R. Strain
Keyword(s):  
Carbon Dioxide ◽  
Water Stress ◽  
Plant Growth ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Potential ◽  
Water Status ◽  
Carbon Dioxide Concentration ◽  
Leaf Water ◽  
Total Leaf

SummaryIf atmospheric carbon dioxide concentration continues to increase, plant growth and crop yield could be affected. New Yorker and Better Boy cultivars of tomato (Lycopersicon esculentum) were used to investigate possible intraspecific variation in the response of crop species to increased CO2. Because precipitation and temperature are predicted to change with the increasing atmospheric CO2 concentration, the response of the two cultivars to the interaction between CO2 and water stress was also examined. Seeds of the two cultivars were germinated and grown under controlled environmental conditions, in either 350 or 675 μ1 CO2/1.The plant water status of the two cultivars was inherently different but was little affected by the CO2 concentration when the plants were well watered. When water was withheld for 5 days the total leaf water potential and osmotic potential decreased in both CO2 treatments but less rapidly in high CO2 than in low. Under low CO2 total leaf water potential decreased to a lower value than osmotic potential. The differences were due, at least in part, to the reduced stomatal conductance and transpiration rate under high CO2.Increased CO2 ameliorated the detrimental effects of drought stress on plant growth. The results indicate that increased CO2 could differentially affect the relative drought resistance of species cultivars.

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