Effects of Bud Scale Removal, Calcium Cyanamide, GA3, and Ethephon on Bud Break of ^|^lsquo;Muscat of Alexandria^|^rsquo; Grape (Vitis vinifera L.)

Abstract

Single-eye cuttings of the grapevine cv. Muscat of Alexandria were collected at monthly intervals from 30 August to 28 February from dormant vines grown in a glasshouse. Various treatments were applied at each time of collection in an attempt to break bud dormancy due to insufficient chilling. Dormancy was broken naturally around 30 January. Bud scale removal greatly reduced dormancy throughout the whole collection period. Application of the supernatant of calcium cyanamide at 20% hastened the termination of dormancy from 30 August to 1 November; thereafter the rate of bud break decreased until 27 December. Bud dormancy was markedly prolonged by GA3 application at 100 p.p.m. during the whole collection period. Ethephon applied at 500 and 1000 p.p.m. on 30 November, when the buds were most dormant, only delayed the termination of bud dormancy.