EPICUTICULAR WAX PRODUCTION, WATER STATUS AND LEAF TEMPERATURE IN TRITICEAE RANGE GRASSES OF CONTRASTING VISIBLE GLAUCOUSNESS

1989 ◽  
Vol 69 (2) ◽  
pp. 513-519 ◽  
Author(s):  
P. G. JEFFERSON ◽  
D. A. JOHNSON ◽  
K. H. ASAY
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Epicuticular Wax ◽  
Leaf Temperature ◽  
Leaf Water ◽  
Total Biomass ◽  
Crested Wheatgrass ◽  
Intermediate Wheatgrass ◽  
Wax Production

Studies were conducted to compare the effect of glaucousness on the response of perennial range grasses to drought stress. Glaucous and nonglaucous plants of an intermediate wheatgrass hybrid (Thinopyrum intermedium (Host) Barkworth and D. R. Dewey × T. intermedium-acutum D.R. Dewey pers. commun.) and an interspecific hybrid of crested wheatgrass (induced tetraploid Agropyron cristatum (L.) Gaertner s. lat. × A. desertorum (Fisch. ex Link) Schultes) were studied in field nurseries for epicuticular wax production, leaf water potential, leaf reflectance of radiation and leaf temperature. Glaucous plants of intermediate wheatgrass had higher epicuticular wax production, increased leaf reflection of radiation, lower midday canopy temperatures, and higher predawn leaf water potentials than non-glaucous plants. Similar trends were observed for the crested wheatgrass hybrids except that glaucousness did not affect midday plant temperatures. A greenhouse experiment involved comparison of glaucous and non-glaucous synthetics of Altai wild ryegrass (Leymus angustus (Trin.) Pilger Dewey). Leaves of glaucous Altai wild ryegrass reflected more radiation and used water less efficiently (total biomass basis) at high soil water content than leaves of the nonglaucous synthetic. At low soil water content, glaucous Altai wild ryegrass had higher leaf temperature and higher midday leaf water potential. Glaucous and nonglaucous Altai synthetics did not differ significantly for shoot yield, total biomass yield, and water use efficiency (shoot yield basis) at either soil water content. While glaucousness may affect water relations of these grasses, it does not necessarily affect forage yield.Key words: Water use efficiency, drought stress, leaf radiation reflectance, crested wheatgrass, intermediate wheatgrass, Altai wild ryegrass

scholarly journals Relationships Among Water Potential Components, Relative Water Content, and Stomatal Resistance of Field-Grown Peanut Leaves1

1984 ◽  
Vol 11 (1) ◽  
pp. 31-35 ◽  
Author(s):  
J. M. Bennett ◽  
K. J. Boote ◽  
L. C. Hammond
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Leaf Water Potential ◽  
Relative Water Content ◽  
Leaf Water ◽  
Peanut Crop ◽  
Relative Water ◽  
Volumetric Soil Water

Abstract Limited data exist describing the physiological responses of peanut (Arachis hypogaea L.) plants to tissue water deficits. Detailed field experiments which accurately define the water status of both the plant and soil are required to better understand the effects of water stress on a peanut crop. The objectives of the present study were 1) to describe the changes in leaf water potential components during a drying cycle, and 2) to define the relationships among soil water content, leaf water potential, leaf turgor potential, relative water content, leaf-air temperature differential, and leaf diffusive resistance as water stress was imposed on a peanut crop. During a 28-day drying period where both rainfall and irrigation were withheld from peanut plants, midday measurements of the physiological parameters and volumetric soil water contents were taken concurrently. As soil drying progressed, water extraction from the upper soil depths was limited as soil moisture approached 0.04 m3m-3. Leaf water potentials and leaf turgor potentials of nonirrigated plants decreased to approximately −2.0 and 0 MPa, respectively, by the end of the experimental period. Leaf water potentials declined only gradually as the average volumetric soil water content in the upper 90 cm of soil decreased from 0.12 to 0.04 m3m-3. Further reductions in soil water content caused large reductions in leaf water potential. As volumetric soil moisture content decreased slightly below 0.04 m3m-3 in the upper 90 cm, leaf relative water content dropped to 86%, leaf water potential approached −1.6 MPa and leaf turgor potential decreased to 0 MPa. Concurrently, stomatal closure resulted and leaf temperature increased above air temperature. Osmotic potentials measured at 100% relative water content were similar for irrigated and nonirrigated plants, suggesting little or no osmotic regulation.

Growth and yield of rice cultivars under sprinkler irrigation in south-eastern Queensland. 3. Water extraction and plant water relations dash comparison with maize and grain sorghum

1988 ◽  
Vol 28 (2) ◽  
pp. 249 ◽  
Author(s):  
S Fukai ◽  
P Inthapan
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Leaf Water Potential ◽  
Osmotic Potential ◽  
Root Length ◽  
Dry Matter ◽  
Root Length Density ◽  
Leaf Water

Several physiological responses were compared, under irrigated and water-stressed conditions, in an attempt to explain the reasons for the greater reduction in dry matter production of rice compared with maize and sorghum in a water-limiting environment. Leaf water potential and leaf rolling were determined weekly, soil water profiles and root length density twice, and leaf osmotic potential once during a long dry period. Root length density of rice was at least as high as that of maize and sorghum in the top 0.6 m layer of soil in both the wet and dry trials. There was no difference in water extraction among the 3 species from this layer, while rice extracted less water than did the other species from below 0.6 m. High variability among replicates precluded any conclusion being drawn regarding root length in the deeper layer. Leaf water potential, measured in the early afternoon, was consistently lower in rice than in maize and sorghum, even when soil water content was high, indicating high internal resistance to the flow of water in the rice plants. The low leaf water potential in rice was accompanied by low osmotic potential, and this assisted in maintenance of turgor and dry matter growth when soil water content was relatively high. As soil water content decreased, however, leaf water potential became very low (less than - 2.5 MPa) and, for rice, leaves rolled tightly.

Photosynthesis and Stomatal-Conductance Responses of Johnsongrass (Sorghum halepense) to Water Stress

Weed Science ◽  
1985 ◽  
Vol 33 (5) ◽  
pp. 635-639 ◽  
Author(s):  
Bryan L. Stuart ◽  
Daniel R. Krieg ◽  
John R. Abernathy
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Osmotic Potential ◽  
Grain Filling ◽  
Leaf Temperature ◽  
Sorghum Halepense

The influence of water stress on johnsongrass [Sorghum halepense(L.) Pers. ♯ SORHA] physiology was evaluated in a semiarid environment. Stomatal conductance of johnsongrass responded to more negative leaf water potential and increasing leaf temperature. The sensitivity of the leaf temperature effect was dependent on the soil water content. At low soil water content, conductance was limited by low water potential, and increasing leaf temperature had little effect. Conductance of CO2was related to net photosynthesis in a curvilinear manner, with conductance levels greater than 0.3 mol·m-2· s-1being in excess of that necessary for maximum photosynthesis. At both high conductance levels and low levels associated with increased water stress, intercellular CO2concentration increased, indicating nonstomatal limitations to photosynthesis. Decreased osmotic potential provided the highest correlation with the linear decline of photosynthetic rate as stress intensified. The expression of osmotic adjustment in johnsongrass is reported during grain filling. Plants in the milkdough stage of grain filling had approximately 0.3 MPa lower osmotic potential at any relative water content than those at anthesis.

TEMPERATURE AND STOMATAL RESISTANCE OF SOYBEAN LEAVES

1979 ◽  
Vol 59 (1) ◽  
pp. 153-162 ◽  
Author(s):  
C. R. SUMAYAO ◽  
E. T. KANEMASU
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Air Temperature ◽  
Canopy Temperature ◽  
Temperature Inversion ◽  
Stomatal Resistance ◽  
Leaf Temperature ◽  
First Case ◽  
Soybean Leaves

A field study was conducted during the 1977 growing season to determine the effect of soil-water content on the air temperature within and above the soybean canopy and consequently on the leaf temperature and stomatal resistance of soybeans (Glycine max L. ’Calland’). Leaf temperature at two heights and air temperature at five heights within and above the canopy were measured with copper-constantan thermocouples while stomatal resistances were measured with an automatic porometer. At soil-water depletions <65%, a daytime air-temperature inversion occurred within and above the canopy, while at depletions >65% air temperature decreased with height. In the first case the canopy temperature was cooler than the air above the canopy when air temperature exceeded 32 °C and the lower canopy leaves were cooler than the upper canopy leaves when they were completely shaded by the upper leaves. At soil-water depletions greater than 65% the canopy was warmer than the air and the lower canopy leaves were warmer than the upper canopy leaves. Stomatal resistance, on the other hand, decreased with height within the canopy irrespective of soil-water content.

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