Studies on the role of abscisic acid in the initiation of bud dormancy in Alnus glutinosa and Betula pubescens.

The effects of leaf-applied (+-)-abscisic acid on the growth and dormancy of Betula pubescens Ehrh. and Alnus glutinosa Gaertn. growing under long days provide no evidence that leaf-applied abscisic acid induces or promotes the formation of resting buds in these species. Radiotracer studies show that a small percentage of the radioactivity applied as [2-(14)C]abscisic acid to the leaves accumulates in the apical region of the shoot. Of the radioactivity that was recovered from this region after 8 days, less than 10% was chromatographically similar to [2-(14)C]abscisic acid. The significance of these results with respect to the role of abscisic acid in regulating the induction of bud dormancy is discussed.