Hormonal Control of Flower Bud Dormancy in Sour Cherry (Prunus cerasus L.). III. Effects of Leaves, Defoliation and Temperature on Levels of Abscisic Acid in Flower Primordia1

Abstract

Levels of both free and bound abscisic acid (ABA) in flower primordia of ‘Montmorency’ sour cherry, as measured by gas-liquid chromatography (GLC), increased during autumn leaf abscission. Mechanical defoliation of trees prior to the onset of leaf abscission prevented this increase in ABA without affecting the intensity of rest. The leaves on forced branches inhibited neither bud break nor flower development, while ABA inhibited both processes. Once the level of ABA had risen naturally, temperature had no effect on its disappearance. These results cast doubt on the involvement of ABA in the control of winter bud dormancy in sour cherry.