hormone that occurs naturally in vines and regulates growth and physiology. It has been shown to be involved in the control of gene expression, thereby influencing certain characteristics of the vine such as the biosynthesis of anthocyanins. Its synthesis is encouraged by physiological stresses including short days and water stress. In the vine, abscisic acid is involved in leaf fall, shoot and root growth, bud dormancy, opening of stomata, and regulation of grape ripening. The irrigation technique partial rootzone drying works by manipulating ABA levels.
