The relations between leaf water potential of cotton plants and environmental and plant factors

An equation for calculating leaf water potential ( Ψ 1) of cotton ( Gossypium hirsutum L.) plants, based on environmental and plant factors, was developed. Two irrigation experiments were conducted with cotton (cv. Acala SJ-2), on a loamy clay soil. Data from 18 treatments of one experiment were pooled and used for multiple regression analysis with Ψ 1 as the dependent variable. The parameter displaying the highest correlation with Ψ 1 was the reciprocal of the relative soil water content in the upper 105 cm of the soil profile. A regression equation combining this factor with air temperature, an index indicating the crop's water stress history and plant height explained 87% of the variation in Ψ 1. The Ψ 1 calculated by using this equation showed good correspondence ( r = 0.9) with data from eight distinct irrigation treatments of the other experiment. It was shown that Ψ 1 of cotton plants can be reliably calculated based on some readily available variables.