Stomatal Response of Cotton to Water Stress and Abscisic Acid as Affected by Water Stress History 1


The threshold leaf water potential required to initiate stomatal closure in cotton (Stoneville 213) became progressively more negative when plants were subjected to a series of water stress cycles. The shift in the threshold water potential required for induction of stomatal closure was dependent on the number of previous stress cycles and leaf age. The basal level of endogenous abscisic acid (ABA) in fully turgid leaves increased in response to the stress treatments, whereas the amount accumulated in response to a subsequent stress did not differ greatly among plants that had experienced different degrees of stress conditioning.

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