The Role of Bud Scales in the Dormancy of Apples

Abstract

Removal of bud scales hastened bud burst of several early and late blooming apple cultivars. Descaling was most effective during the onset and end of rest. During deep rest, bud scale removal was effective only when applied 2 weeks before forcing conditions. Extracts of bud scales inhibited apple bud break in vitro. Abscisic acid (ABA) may have been responsible for part or all of this bioactivity, since ABA occurred in bud scale diffusates and could replace or reinforce the bud scales in vitro. Wound-produced ethylene was not involved in the bud scale removal response.

Effects of Shoot, Root, and Shank Chilling during Rest in Apple and Peach on Growth Resumption and Carbohydrates

“…That apple shoots also must be chilled indicates some changes occur within the buds which enhance effectiveness of root cytokinins. These changes may involve a reduction of growth inhibitors in the bud or bud scales (18,22), and/or a change in sensitivity of the bud tissues (19). Chilling the root or shoot alone is partially effective in promoting budbreak in apple, but the results thus far indicate both must be chilled for maximum budbreak to occur.…”