Water Relations of Cotton Plants under Nitrogen Deficiency: III. STOMATAL CONDUCTANCE, PHOTOSYNTHESIS, AND ABSCISIC ACID ACCUMULATION DURING DROUGHT 1

摘要

Nitrogen nutrition exerted a strong effect on stomatal sensitivity to water stress in cotton. In well-watered plants grown with 0.31 millimolar N in the nutrient solution, stomata closed at a water potential of -9 bars even though the wilting point was below -15 bars. For each doubling of nutrient N level, the water potential for stomatal closure decreased by about 2 bars. Elevated intercellular CO2 concentrations caused only slight stomatal closure regardless of N nutrition. Exogenous abscisic acid (ABA) greatly increased stomatal sensitivity to elevated CO2 concentrations.