Adaptation to Water Stress of the Leaf Water Relations of Four Tropical Forage Species

1980 ◽  
Vol 7 (2) ◽  
pp. 207 ◽  
Author(s):  
JR Wilson ◽  
MM Ludlow ◽  
MJ Fisher ◽  
E Schulze
Keyword(s):  
Water Stress ◽  
Water Content ◽  
Water Relations ◽  
Bound Water ◽  
Leaf Tissue ◽  
Dry Weight ◽  
Panicum Maximum ◽  
Soil Drying ◽  
Buffel Grass ◽  
Heteropogon Contortus

Three tropical grasses, green panic (Panicum maximum var, trichoglume), spear grass (Heteropogon contortus) and buffel grass (Cenchrus ciliaris) and the tropical legume siratro (Macroptilium atropurpureum), were grown in plots in a semi-arid field environment. The water relations characteristics of leaves from plants subjected to a soil drying cycle were compared with those of unstressed leaves from plants in irrigated plots. Minimum water potentials attained in the stressed leaves were c. -44, - 38, - 33 and - 13 bar for the four species, respectively. The grass leaves adjusted osmotically to water stress, apparently through accumulation of solutes, so that there was a decrease in osmotic potential at full turgor (Ψπ100) of 5.5, 3.9 and 7.1 bar, and in water potential at zero turgor (Ψ0) of 8.6, 6.5 and 8.6 bar for green panic, spear grass and buffel respectively. Water stress appeared to increase slightly the proportion of bound water (B) and the bulk modulus of elasticity (ε) of the grass leaves, but it did not alter the relative water content at zero turgor (RWC0) or the ratio of turgid water content to dry weight of the tissue. The Ψπ100 and Ψ0 of stressed siratro leaves decreased by 2.5-4 bar and 3-5 bar respectively when subjected to soil drying cycles. These changes could be explained by the marked decrease in the ratio of turgid water content to dry weight of the leaf tissue rather than by accumulation of solutes. The values of RWC0 and ε for siratro leaves were not altered by stress but, in contrast to the grasses, B was apparently decreased although the data exhibited high variability. Adjustments in Ψπ100 and Ψ0 of stressed leaves of buffel grass and siratro were largely lost within 10 days of rewatering.

Time Trends for Change in Osmotic Adjustment and Water Relations of Leaves of Cenchrus ciliaris During and After Water Stress

1983 ◽  
Vol 10 (1) ◽  
pp. 15 ◽  
Author(s):  
JR Wilson ◽  
MM Ludlow
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Water Relations ◽  
Osmotic Adjustment ◽  
Leaf Growth ◽  
Weight Ratio ◽  
Bound Water ◽  
Arid Environment ◽  
Leaf Water ◽  
Buffel Grass

Buffel grass was subjected to a soil drying cycle for 5 weeks in a semi-arid environment. As water stress developed, the leaf water relations characteristics of these plants (Dry treatment) were compared with those of irrigated plants (Wet treatment). Leaf water potential (Ψ) of the Dry treatment measured at 1400 h decreased to a minimum of -6.9 MPa. The stressed leaves adjusted osmotically, with the osmotic potential at full turgor (Ψπ100) decreasing (becoming more negative) linearly with time (0.017 MPa day-1) and with decreasing water potential measured at 1400 h (0.11 MPa per 1 MPa decrease in Ψ). Maximum osmotic adjustment (Ψπ100 Wet -Ψπ100 Dry) was 0.66 MPa, and this change together with lower cell wall elasticity decreased by 1.03 MPa the water potential (Ψ0) at which the stressed leaves lost turgor. Differences between the stress- acclimated Dry leaves and the Wet leaves in bound water, turgid weight:dry weight ratio and the relative water content at which they reached zero turgor were small and inconsistent. At 18 days after rewatering, the Ψπ100 value of acclimated leaves was still 0.18 MPa lower than that of the control leaves. The substantial shift in Ψ0 gained the stress-acclimated leaves only one extra day before they lost turgor at 1400 h, and only 2.5 extra days before being permanently wilted. This small gain in time and the rapid cessation of leaf growth even before positive turgor was completely lost suggests that osmotic adjustment may not contribute greatly to continued leaf growth in water-stressed plants of buffel grass.

Leaf water potentials of pasture plants in a semi-arid subtropical environment

1975 ◽  
Vol 15 (76) ◽  
pp. 645 ◽  
Author(s):  
DCI Peake ◽  
GD Stirk ◽  
EF Henzell
Keyword(s):  
Water Stress ◽  
Leaf Water ◽  
Panicum Maximum ◽  
Research Station ◽  
Buffel Grass ◽  
Heteropogon Contortus ◽  
Drought Avoidance ◽  
Water Potentials ◽  
Severe Water Stress ◽  
Pasture Plants

Leaf water potentials (�1) were measured on pasture plants at the Narayen Research Station in southern Queensland. The main findings were: 1. There were marked differences between species in the value of �1, measured during drought. Lucerne (Medicago sativa cv. Hunter River) and buffel grass (Cenchrus ciliaris cv. Biloela) usually showed a lower (i.e. more negative) �1 than Siratro (Macroptilium atropurpureum cv. Siratro), when they were grown together in a mixed pasture. Siratro seemed to possess a useful degree of drought avoidance. High drought resistance was observed in buffel grass; this was attributed to its tolerance of water stress. Green panic (Panicum maximum var. trichoglume cv. Petrie) was found to have as low a �1 as lucerne during drought when the two species were grown with Siratro in a mixed pasture. 2. The plants were under severe water stress before all the available water was removed from the deeper soil horizons. 3. �1 was lower in nitrogen-fertilized buffel grass or spear grass (Heteropogon contortus), than in the corresponding unfertilized controls. 4. The vapour-exchange and dye-marker densiometric methods gave different values for �1 in buffel grass, green panic and Siratro; the vapour exchange technique recorded lower, i.e, more negative figures than the other method when the plants were under severe water stress. The two methods gave similar values for lucerne. The relation between the values obtained for buffel grass by the two methods was affected by nitrogen fertilization. The reaction of sown pasture plants to drought at Narayen is discussed.

Influence of Water Deficits on the Water Relations Characteristics and Productivity of Wild and Cultivated Sunflowers

1983 ◽  
Vol 10 (2) ◽  
pp. 195 ◽  
Author(s):  
MA Sobrado ◽  
NC Turner
Keyword(s):  
Water Stress ◽  
Water Content ◽  
Water Relations ◽  
Dry Matter ◽  
Weight Ratio ◽  
Dry Weight ◽  
Dry Matter Accumulation ◽  
Water Deficits ◽  
Influence Of Water ◽  
In The Wild

The effects of water deficits on the water relations characteristics and yield of two cultivated Helianthus annuus L. lines, Hysun 31 and Seneca, and two wild Helianthus species, H. nuttallii and H. petiolaris, were compared. The study was conducted on frequently irrigated and unirrigated plants growing in the field during the summer. Predawn measurements of leaf water potential and relative water content showed that, in the uninigated plants, water deficits increased in all species during the first month after sowing (period I), were relieved by rain in the second month (period II), and then increased progressively in the final month (period III). The osmotic potential at full turgor of unirrigated plants, estimated by pressure-volume curves, decreased by 0.12-0.22 MPa during periods I and III in the cultivated sunflowers, but did not decrease significantly in the wild sunflowers. Except in the irrigated Hysun 31 and Seneca during period I, the apoplastic water content was about 20% in all species and treatments. During period I, the turgid weight: dry weight ratio decreased significantly with water stress, particularly in the cultivated sunflowers; the changes were less marked in the wild sunflowers and during period III. Additionally, the turgid weight: dry weight ratio in the imgated cultivated sunflowers decreased throughout the season. The volumetric modulus of elasticity was similar among species and did not change with water stress or plant age. Dry matter accumulation was smaller in the wild species than in the cultivated lines; water stress reduced shoot dry matter similarly in all species. However, water deficits significantly reduced the seed yield only in Hysun 31 and Seneca.

Changes in Levels of Solutes During Osmotic Adjustment to Water Stress in Leaves of Four Tropical Pasture Species

1981 ◽  
Vol 8 (1) ◽  
pp. 77 ◽  
Author(s):  
CW Ford ◽  
JR Wilson
Keyword(s):  
Water Stress ◽  
Organic Acids ◽  
Osmotic Adjustment ◽  
Inorganic Ions ◽  
Arid Environment ◽  
Low Molecular Weight ◽  
Panicum Maximum ◽  
Buffel Grass ◽  
Heteropogon Contortus ◽  
Macroptilium Atropurpureum

Three tropical grasses, green panic (Panicum maximum var. trichoglume), buffel grass (Cenchrus ciliaris), and spear grass (Heteropogon contortus), and a tropical legume, siratro (Macroptilium atropurpureum), were field-grown in a semi-arid environment. One set of plants was well watered, while another set was subjected to a continuous 35-day drying cycle. Samples of specific leaves were taken at the beginning, middle and end of the drying cycle, and 1, 5 and 14 days after rewatering. The major low-molecular-weight solutes which accumulated in the grasses during water stress were the inorganic ions sodium (green panic), potassium (buffel and spear grass) and chloride (all grasses). Accumulation of these ions largely accounted for the osmotic adjustments determined from a previous study of water relations of the leaves. Concentrations of the minor constituents glucose and fructose increased only slightly in the stressed grasses, whereas levels of sucrose, the major carbohydrate component, increased substantially, particularly in spear grass. Inositol accumulated to a small extent in spear grass. Differences between the grasses were evident in the organic acid spectrum and also in changes in concentration of organic acids due to water stress. In water-stressed tissue, malate levels increased in green panic and spear grass but were reasonably constant in buffel grass. Aconitate concentrations (not detected in buffel grass) decreased in stressed green panic, but increased in spear grass. Oxalate (only trace quantities in spear grass) was a major component in green panic and buffel grass, but did not appear to vary with increase in water stress. Succinate accumulated only in stressed spear grass. The contribution of carbohydrates and organic acids to the osmotic adjustment was relatively small. Proline accumulated to varying degrees in all stressed grasses. Betaine occurred only in trace amounts in spear grass, but accumulated substantially in green panic and buffel grass. Water-stressed leaves of siratro did not accumulate inorganic ions, sugars, organic acids, proline or betaine, but pinitol levels increased. Implications of the results relating osmotic adjustment to changes in chemical composition are discussed.

scholarly journals In vitro screening of rice genotypes using polyethylene glycol under drought stress

2016 ◽  
Vol 27 (2) ◽  
pp. 128-135 ◽  
Author(s):  
J Akte ◽  
S Yasmin ◽  
MJH Bhuiyan ◽  
F Khatun ◽  
J Roy ◽  
...  
Keyword(s):  
Water Stress ◽  
Drought Stress ◽  
Water Content ◽  
Relative Water Content ◽  
Dry Weight ◽  
Proline Accumulation ◽  
Shoot Length ◽  
Fresh Weight ◽  
Relative Water

Five rice varieties viz. Binadhan-4, Binadhan-5, Binadhan-6, Binadhan-10 and Iratom-24 were evaluated in vitro under different water stress conditions. Several parameters such as germination percentage, shoot length, root length, shoot-root ratio, fresh weight, dry weight, turgid weight, relative water content and proline accumulation were studied. Drought condition was created by MS medium supplemented with five treatments of PEG, with a control such as 0%, 1%, 2%, 3% and 4% of PEG. The highest germination (100%) was found in the variety Binadhan-10 under low water stress conditions induced by 1% PEG. Similarly, the highest percentage of germination was found in all varieties under control condition (0% PEG). The lowest percentage of germination was obtained in the variety Iratom-24. But under severe stress (4% PEG), the highest percentage of germination was found only in the variety Binadhan-10. Moreover, the variety Binadhan-10 was found to be the best at 4% PEG for shoot length, root length, shoot-root ratio, relative water content and also the best at 1% PEG for fresh weight, dry weight, turgid weight. Water stress decreased relative water content and increased proline accumulation in rice. The highest relative water content was recorded in the variety Binadhan-10 and the lowest value recorded in the variety Binadhan-5. The highest proline content was obtained from the binadhan-6 at the highest treatment (4% PEG). Binadhan-10 showed the best performance almost in all the parameters under drought stress because of its own nature of tolerancy.Progressive Agriculture 27 (2): 128-135, 2016

An Equilibrium Model of Leaf Water Potentials Which Separates Intra- and Extracellular Potentials

1975 ◽  
Vol 2 (3) ◽  
pp. 253 ◽  
Author(s):  
B Acock
Keyword(s):  
Water Content ◽  
Turgor Pressure ◽  
Bound Water ◽  
Leaf Tissue ◽  
High Water ◽  
Leaf Water ◽  
High Water Content ◽  
Pressure Potential ◽  
Matrix Bound ◽  
Water Contents

A model is proposed which makes it possible to estimate the intracellular turgor pressure potential, intracellular osmotic plus matric potential, and intra- and extracellular soIution fractions of water in leaf tissue at any water content. The model requires only the data normally collected with a thermocouple psychrometer: total water potential of live and dead (cells ruptured) tissue at various known water contents. The major assumptions are that (1) the total potential of water in the solution fraction in any part of the tissue multiplied by the volume of water is constant; (2) extracellular water experiences no pressure potential; (3) matrix-bound water is held only by matric forces and contains no solute; (4) the solution fraction of the intracellular water is constant at high water content; and (5) matrix-bound water content is constant over the range of leaf water contents normally examined. The models developed to deal with pressure bomb data are examined critically and doubts are cast on the validity of some of their assumptions.

The Effect of Mild Water Deficit on Basil Yield and Quality

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 517e-517
Author(s):  
Jennifer Warner ◽  
Albert H. Markhart
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Soil Water Potential ◽  
Leaf Tissue ◽  
Dry Weight ◽  
Secondary Compounds ◽  
Matric Potential ◽  
Taste Test ◽  
Sweet Basil ◽  
Flavor Components

Secondary compounds, essential oils, and flavor components of leaf tissue often increase in response to environmental stress. The objective of this study is to determine if a simple measure of soil matric potential could be used to generate mild plant water stress in sweet basil, which would improve the flavor components of the foliage. Sweet basil was grown in Universal Soil Mix with adequate water and fertilization in greenhouses supplied with 18 h of high-pressure sodium supplemental lighting until the third pair of leaves was fully expanded. Aquaprobe matric potential sensors were installed in the center of the pot and soil matric potentials recorded daily. Water was withheld from stressed plants until the soil water potential reached –4 bars. Treatments consisted of one or two stress cycles. Plants were harvested 24 h after rewatering and fresh and dry weights determined. The youngest two fully expanded leaves were placed in zip log bags and used in a taste test. The two water stress treatments decreased leaf fresh weight by 10% and 16%, respectively, decreased total plant dry weight by 6% and 10%, respectively, and had moderate effect on flavor intensity as rated by our taste test panel. The substantial decrease in yield suggests that –4 bars was too severe a stress to be used commercially. The Aquaprobe sensor was an easy to use economical way to monitor soil water and could be useful in regulating watering in a greenhouse environment.

Differential responses of accessions of native Australian Nicotiana species to water stress

2018 ◽  
Vol 66 (3) ◽  
pp. 265 ◽  
Author(s):  
Khondoker M. G. Dastogeer ◽  
Hua Li ◽  
Krishnapillai Sivasithamparam ◽  
Michael G. K. Jones ◽  
Stephen J. Wylie
Keyword(s):  
Water Stress ◽  
Water Content ◽  
Relative Water Content ◽  
Dry Weight ◽  
Shoot Tip ◽  
Initial Symptom ◽  
Fresh Weight ◽  
Nicotiana Species ◽  
Water Stress Tolerance ◽  
Relative Water

Thirty-two accessions of four Nicotiana species (Nicotiana benthamiana Domin, Nicotiana occidentalis H.-M.Wheeler, Nicotiana simulans N. Burb. and Nicotiana umbratica N.T.Burb.) collected from wild plants in northern Australia were assessed for responses to water stress. Under moderate water stress conditions, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, root : shoot ratio, and relative water content of leaves were significantly affected. However, the degree to which the accessions were affected varied considerably. Some accessions of N. simulans, N. benthamiana and N. occidentalis were significantly more affected by water stress than others. There was significant variation between accessions in leaf and shoot tip wilting times. Initial symptom expression (leaf wilting) was significantly delayed in three accessions of N. benthamiana, and in one accession of N. umbratica. The least water stress tolerant lines, two accessions each of N. benthamiana, N. occidentalis and N. simulans, exhibited advanced symptoms of water stress (shoot tip wilting) within 14–17 days of cessation of watering. This stage was significantly delayed in three accessions of N. benthamiana and two accessions N. occidentalis and one accession of each of N. simulans and N. umbratica, which showed tip wilting only after 21–24 days. There were variations among the accessions of same Nicotiana species on their tolerance to water stress. Plant responses to water stress could not be predicted from their plant biomass and leaf relative water content under well-watered conditions. Leaf chlorophyll content was variable under water stress, but did not correlate with water stress tolerance.

scholarly journals WATER CONTENT IN PRIMARY GRAPE BUDS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 654e-654
Author(s):  
A. A. Gardea ◽  
P. B. Lombard ◽  
R. L. Kohnert ◽  
A. N. Azarenko ◽  
Y. M. Moreno ◽  
...  
Keyword(s):  
Water Content ◽  
Water Status ◽  
Bound Water ◽  
Free Fraction ◽  
Dry Weight ◽  
Pinot Noir ◽  
Free Form ◽  
Vascular Connection ◽  
H Nmr ◽  
Dormant Season

Changes in water content of `Pinot Noir' endo- and ecodormant primary buds were gravimetrically partitioned into extracellular (ECW) and intracellular water (ICW). During endodormancy, water status remained unchanged with values of 0.6 and 0.1 mg/mg dw for ICW and ECW, respectively. Ecodormant buds, prior to budbreak, increased in ICW from 0.5 to 4.4 mg/mg dry weight for Jan. and Apr., respectively. Liquid water in the buds was determined by H-NMR. The spin-spin relaxation time (T2) at -30C represented the bound fraction, which peaked in Jan. at 0.3 mg/mg dw followed by a decrease to 0.2 mg/mg dw in March. During the dormant season the free fraction was always larger than the bound fraction. No vascular connection between bud and stem was observed by mid Jan. Changes in bound water indicated that there is a transient fraction changing to the free form. These changes were not strictly related to the bud's dormancy status.

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