In order to sustain plant growth and hydration, water must be continuously supplied to the leaf as it is lost by transpiration. This becomes especially difficult under low soil moisture conditions. The objective of this investigation was to compare peanut (Arachis hypogaea L.) genotypes for their ability to maintain water supply to leaves by measuring apparent sap velocity (Va) under water stress conditions. Va was determined by the thermoelectric heat pulse method. Three genotypes (Chico, Florunner, and PI 355993) that differed in rooting traits were studied in the greenhouse. Plants were grown in fritted clay in PVC tubes (10.2 cm inside diameter and 76.2 cm in length). Six genotypes, including Chico and PI 355993, were studied in the field. Soil type was Teller sandy loam (fine, mixed, thermic, Udic Argiustoll). Under control conditions in the greenhouse and irrigated conditions in the field, Va ranged from about 0.8 to 1.1 cm/min for all genotypes. As water was withheld, Va declined with time in the greenhouse and was significantly lower under rainfed (-0.25 MPa soil potential) than irrigated (-0.10MPa soil potential) conditions in the field. Significant genotypic differences were found in both greenhouse and field experiments. Chico maintained the highest Va ratio (stress Va/control Va) in the greenhouse. PI 404021, Chico, and PI 355993 showed the least reduction (20, 26, and 29%, respectively) in Va under rainfed conditions in the field. Thus, the data are indicative of differences among peanut genotypes in maintaining Va under stress conditions. Knowledge of Va could be useful in determining relationships between root activity, soil water content, and water uptake and in selecting genotypes for inclusion in breeding programs to develop cultivars that avoid drought stress.
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Keywords: Arachis hypogaea L, Groundnut, Water stress, transpiration, water flow, water potential, root resistance, thermoelectric heat pulse, drought tolerance
How to Cite:
Ketring, D. & Erickson, P. & Stone, J.,
(1990) “Apparent Sap Velocity in Peanut Genotypes Under Control and Stress Conditions¹”,
Peanut Science 17(1),
01 Jan 1990