Interaction of Nitrogen and Water Deficits on Stomatal Behavior in Cotton

Abstract

Stomata of normal and mildly N-deficient cotton plants (Gossypium hirsutum L.) reacted very differently to water stress. In N-deficient plants, stomata closed at water potentials up to 10 bars higher than in normal plants. Data presented here show: 1) stomata of both normal and N-deficient plants responded little to intercellular CO2 concentrations (Ci) before the imposition of drought; 2) during drought, stomata became sensitive to C-i, closing at elevated concentrations; 3) stomata of N-deficient plants began to respond to C-i at a higher water potential than those of normal plants; 4) sensitivity to Ci was also induced by application of abscisic acid (ABA). The results strongly imply that in N-deficient plants, ABA was synthesized at higher water potentials than in normal plants.