Relation of Soybean Leaf Water Potential to Soil Water Potential¹

Abstract

Abstract Estimation of plant water potential is a possible aid in irrigation scheduling. This work examined the relation of maximum and minimum soybean ( Glycine max (L.) Merr.) leaf water potential to soil water potential. Maximum readings were taken near sunrise and minimum readings were taken between 1300 and 1500 CDT. Leaf water potentials were measured with a pressure chamber and soil water potentials were estimated using moisture release curves and volumetric soil moisture measurements made with a neutron probe. Leaf water potentials decreased an average of 9 to 10 bars as a result of daily atmospheric evaporative demand during the vegetative stage. Soybean leaf water potential was as responsive to changes in soil water potential during the podding stage as during the vegetative stage. Data indicated the possibility of estimating soil water potential from early morning values of soybean leaf water potential.