scholarly journals THE EFFECT OF LEAF WATER STRESS AND AGE ON PHOTOSYNTHESIS IN STRAWBERRY PLANTS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 655c-655
Author(s):  
Llngxiao Zhang
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Osmotic Adjustment ◽  
Leaf Water ◽  
Severe Stress ◽  
Drying Process ◽  
Stomatal Limitation ◽  
Preliminary Results ◽  
Water Potentials ◽  
Young Leaves

The effect of water stress on photosynthesis was investigated in strawberry plants to see responses of different aged-leaves within the same plant. Preliminary results indicated that, under severe stress (SS) conditions, young leaves had lower water potentials and higher photosynthetic CO2 assimilation rates than old leaves had, due to higher stomatal conductance in young leaves. This situation was not found in moderately stressed or well–watered plants, probably because of the higher non-stomatal limitation in old leaves under SS condition. Under SS condition, old leaves had a higher intracellular CO2 concentration. Osmotic adjustment or acclimation might occur during slow drying process, so that the young leaves could adjust their stomata and still remain open under low water potentials.

Effect of Water Stress on Stomatal Conductance and Leaf Water Relations of Leaves Along Current-Year Branches of Peach

1989 ◽  
Vol 16 (6) ◽  
pp. 549 ◽  
Author(s):  
SL Steinberg ◽  
MJ Mcfarland ◽  
JC Miller
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Water Status ◽  
Stomatal Closure ◽  
Water Flux ◽  
Leaf Water ◽  
Leaf Water Status ◽  
Mature Leaves ◽  
Water Potentials

A gradation, that reflects the maturity of the leaves, exists in the leaf water, osmotic and turgor potential and stomatal conductance of leaves along current and 1-year-old branches of peach. Predawn leaf water potentials of immature folded leaves were approximately 0.24 MPa lower than mature leaves under both well-watered and dry conditions. During the daytime the leaf water potential of immature leaves reflected the water potential produced by water flux for transpiration. In well- watered trees, mature and immature unfolded leaves had a solute potential at least 0.5 MPa lower than immature folded leaves, resulting in a turgor potential that was approximately 0.8 MPa higher. The turgor requirement for growth appeared to be much less than that maintained in mature leaves. As water stress developed and leaf water potentials decreased, the osmotic potential of immature folded leaves declined to the level found in mature leaves, thus maintaining turgor. In contrast, mature leaves showed little evidence of turgor maintenance. Stomatal conductance was lower in immature leaves than in fully mature leaves. With the onset of water stress, conductance of mature leaves declined to a level near that of immature leaves. Loss of turgor in mature leaves may be a major factor in early stomatal closure. It was concluded that osmotic adjustment played a role in maintenance of a leaf water status favorable for some growth in water-stressed immature peach leaves.

Stomatal and photosynthetic response of drought-stressed cherrybark oak (Quercusfalcata var. pagodaefolia) and sweet gum (Liquidambarstyraciflua)

1986 ◽  
Vol 16 (4) ◽  
pp. 841-846 ◽  
Author(s):  
S. R. Pezeshki ◽  
J. L. Chambers
Keyword(s):  
Stomatal Conductance ◽  
Stomatal Closure ◽  
Net Photosynthesis ◽  
Leaf Water ◽  
Dominant Factor ◽  
Controlled Environment ◽  
Photosynthetic Response ◽  
Stomatal Limitation ◽  
Water Potentials ◽  
Relative Decline

The effects of water stress on stomatal conductance and net photosynthesis of cherrybark oak (Quercusfalcata var. pagodaefolia Ell.) and sweet gum (Liquidamberstyraciflua L.) seedlings were studied under controlled environment conditions during the 1983 growing season. Drought stress induced stomatal closure and significant declines in net photosynthesis for both species. Stomatal conductance declined by as much as 43% in cherrybark oak and 82% in sweet gum compared with predrought levels. Net photosynthetic rates also declined 85% from predrought levels in sweet gum and fell below zero in cherrybark oak. The remarkable decline in net photosynthesis in cherrybark oak while stomata remained partially open suggests that in addition to a stomatal effect, nonstomatal factors were involved in the reduction of net photosynthesis. In sweet gum, however, stomatal limitation of net photosynthesis seems to be the dominant factor. The greater relative decline in mean leaf conductance in sweet gum suggests a greater reaction to drought by this species through effective and rapid stomatal closure resulting in avoidance of leaf desiccation. Stomata of cherrybark oak, on the other hand, were less sensitive to low leaf water potentials; therefore, stomatal closure occurred at significantly lower (more negative) leaf water potentials when compared with sweet gum.

scholarly journals Influence of Osmotic Adjustment on the Growth, Stomatal Conductance and Light Interception of Contrasting Sorghum Lines in a Harsh Environment

1990 ◽  
Vol 17 (1) ◽  
pp. 91 ◽  
Author(s):  
DJ Flower ◽  
AU Rani ◽  
JM Peacock
Keyword(s):  
Stomatal Conductance ◽  
Osmotic Adjustment ◽  
High Capacity ◽  
Leaf Water ◽  
Harsh Environment ◽  
Leaf Rolling ◽  
Drought Period ◽  
Water Potentials ◽  
Air Temperatures ◽  
Resistant Lines

Two drought resistant lines of sorghum, IS 13441 and IS 1347, with a high capacity for osmotic adjustment and two susceptible lines, IS 12739 and IS 12744, were subjected to drought in the field during a summer season in the semi-arid tropics in India. During this season there is little rain, air temperatures reach 42°C, and pan evaporation rates may reach 20 mm d-1 providing a harsh environment for crop growth. Most of the osmotic adjustment occurred within 3 weeks after withholding water and at high predawn leaf water potentials, i.e. at values above - 1.0 MPa. As a result, resistant lines were able to maintain a positive turgor to lower leaf water potentials (- 2.8 MPa) than susceptible lines (- 2.0 MPa). Nevertheless, dry matter production was negligible in both resistant and susceptible lines when predawn leaf water potentials fell to - 0.55 MPa. Furthermore, throughout the drought period the leaf area of all water-stressed plants was similar when expressed relative to the control regardless of the level of osmotic adjustment. Resistant lines had similar stomatal response to leaf water potential as susceptible lines. Large changes occurred in stomatal conductance and leaf rolling soon after withholding water while there was considerable osmotic adjustment in the leaves. Leaf rolling coincided with a reduction in the ability of the plant to utilise radiation. Therefore, even if osmotic adjustment had delayed leaf rolling, the gain in productivity would be small. On the basis of these turgor related processes it can be concluded that there would be little advantage in selecting for plants with a higher capacity for osmotic adjustment in this harsh environment.

Effects of severity and repetition of water stress on seed production of Macroptilium atropurpureum cv. Siratro

1987 ◽  
Vol 38 (3) ◽  
pp. 529 ◽  
Author(s):  
L Kowithayakorn ◽  
LR Humphreys
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Seed Production ◽  
Leaf Water Potential ◽  
Leaf Water ◽  
Severe Stress ◽  
Constant Height ◽  
Young Leaves ◽  
Macroptilium Atropurpureum ◽  
Leaf Differentiation

Macroptilium atropurpureum cv. Siratro was grown in large soil beds in a glasshouse with a water table at constant height below. Water stresses of dawn leaf water potential of - 1.0 MPa (medium stress) or of - 1.5 MPa (severe stress) were developed over 14 or 28 days, either singly or repeated after 42 days of rewatering. These stresses caused some death of terminal shoots and abscission of old leaves, but rapid rates of leaf differentiation restored leaf density to the levels of the control plants upon rewatering. A subsidiary experiment showed lower levels of leaf water potential in young leaves near the apex than in leaves subtending inflorescences.Persistent increases in the rate of floral bud appearance occurred upon rewatering, but the ratio of floral buds surviving to form an inflorescence with flowers was reduced both during and after the imposition of stress. A single cycle of medium stress increased seed yield 36% relative to the control plants, due to increased inflorescence and flower density. Repetition of water stress after 42 days was disadvantageous, and the effects of longer intervals between stress merit investigation. Severe stress of - 1.5 MPa was not beneficial to seed production.

The Influence of Water Stress on the Physiology and Competition of Soybean (Glycine max) and Florida Beggarweed (Desmodium tortuosum)

Weed Science ◽  
1989 ◽  
Vol 37 (4) ◽  
pp. 544-551 ◽  
Author(s):  
Blair S. Griffin ◽  
Donn G. Shilling ◽  
Jerry M. Bennett ◽  
Wayne L. Currey
Keyword(s):  
Glycine Max ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Soil Water ◽  
Leaf Water ◽  
Water Potentials ◽  
Influence Of Water ◽  
Soybean Leaf ◽  
Different Levels ◽  
Optimum Water

Replacement studies were conducted under greenhouse conditions to determine if available soil water influences the competitive interaction between soybean and Florida beggarweed. Stomatal conductance and leaf water potential were determined for both species under different levels of available soil water to identify possible mechanisms involved in changes in the relative competitiveness induced by the water deficits. Soybean leaf area and aboveground biomass were greater than for Florida beggarweed under optimum water, but equal to or less than Florida beggarweed with water stress. Soybean was more competitive than Florida beggarweed when there was adequate soil water but less competitive than Florida beggarweed under water stress. Stomatal conductance was higher for soybean with optimum soil water (at high leaf water potentials) but equal to Florida beggarweed as soil water became limiting (low leaf water potentials). These data indicated that water stress differentially affected soybean and Florida beggarweed.

Water stress affects the productivity, growth components, competitiveness and water relations of phalaris and white clover growing in a mixed pasture

1992 ◽  
Vol 43 (3) ◽  
pp. 659 ◽  
Author(s):  
L Guobin ◽  
DR Kemp ◽  
GB Liu
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
White Clover ◽  
Leaf Growth ◽  
Leaf Water ◽  
Water Potentials ◽  
Relative Water ◽  
Dry Conditions ◽  
Leaf Appearance ◽  
Water Contents

The effect of water stress during summer and recovery after rain on herbage accumulation, leaf growth components, stomatal conductance and leaf water relations of white clover (Trifolium repens cv. Haifa) and phalaris (Phalaris aquatica cv. Australian Commercial) was studied in an established mixed pasture under dryland (dry) or irrigated (wet) conditions. Soil water deficits under dry conditions reached 150 mm and soil water potentials in the top 20 cm declined to nearly -2 MPa after 50 days of dry weather. Water stress severely restricted growth of both species but then after rain fell, white clover growth rates exceeded those of phalaris. Under irrigation, white clover produced twice the herbage mass of phalaris but under dry conditions herbage production was similar from both species. Leaf appearance rates per tiller or stolon were slightly higher for white clover than phalaris but were reduced by 20% under water stress in both species. Leaf or petiole extension rates were more sensitive to water stress than leaf appearance rates and declined by 75% in phalaris and 90% in white clover. The ratio of leaf or petiole extension rates on dry/wet treatments was similar for both species in relation to leaf relative water contents, but in relation to leaf water potentials phalaris maintained higher leaf growth rates. Phalaris maintained a higher leaf relative water content in relation to leaf water potentials than did white clover and also maintained higher leaf water potentials in relation to the soil water potential in the top 20 cm. Stomata1 conductances for both species declined by 80-90% with increasing water stress, and both species showed similar stomatal responses to bulk leaf water potentials and leaf relative water contents. It is suggested that the poorer performance of white clover under water stress may be due principally to a shallower root system than phalaris and not due to any underlying major physiological differences. The white clover cultivar used in this study came from the mediterranean region and showed some different responses to water stress than previously published evidence on white clover. This suggests genetic variation in responses to water stress may exist within white clover. To maintain white clover in a pasture under dry conditions it is suggested that grazing practices aim to retain a high proportion of growing points.

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

2004 ◽  
Vol 16 (3) ◽  
pp. 155-161 ◽  
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.

Osmotic Adjustment: Effect of Water Stress on Carbohydrates in Leaves, Stems and Roots of Apple

1995 ◽  
Vol 22 (5) ◽  
pp. 747 ◽  
Author(s):  
Z Wang ◽  
B Quebedeaux ◽  
GW Stutte
Keyword(s):  
Water Stress ◽  
Osmotic Adjustment ◽  
Sucrose Concentration ◽  
Starch Content ◽  
Soluble Carbohydrates ◽  
Soluble Carbohydrate ◽  
Malus Domestica Borkh ◽  
Mature Leaves ◽  
Young Leaves ◽  
Response To Water

Potted apple (Malus domestica Borkh. cv. Jonathan) trees were subjected to water stress in a greenhouse. Midday leaf water potential (ΨW), osmotic potential (ΨS), soluble carbohydrates, and starch content of expanding and mature leaves, stems, and roots were measured to determine whether active osmotic adjustment occurred and if water stress affected carbohydrate metabolism. Mature leaves had the highest total soluble carbohydrate level (357 mM) and lowest Ψ (-1.85 MPa), followed by young leaves (278 mM, -1.58 MPa), stems (115 mM, -1.02 MPa), and roots (114 mM, -0.87 MPa). Sorbitol was the major component in all organs ranging from 53% of total soluble carbohydrate in young leaves to 73% in mature leaves. When ΨW decreased from -1.0 to -3.2 MPa, active osmotic adjustments of 0.3-0.4 MPa were observed in mature leaves, stems, and roots while a significantly higher adjustment of 1.0 MPa was detected in young leaves 5 days after the initiation of water stress. Sorbitol levels in leaves and stems gradually increased as ΨW decreased from -1.0 to -2.5 MPa, and then remained relatively stable or decreased slightly as ΨW decreased from -2.5 to -3.2 MPa. However, the percentage of soluble carbohydrate as sorbitol in roots decreased in response to water stress. Sucrose concentration decreased in mature leaves and stems, but increased in young leaves and roots as ΨW decreased. Starch concentrations in stems and roots also decreased as water stress developed. The sorbitol to sucrose ratios increased in mature leaves, but decreased in roots in response to water stress.

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