Effects of Bud Scale Removal, Calcium Cyanamide, GA₃, and Ethephon on Bud Break of ‘Muscat of Alexandria’ Grape (Vitis vinifera L.)

Abstract

Experiments were conducted to determine the effects of bud scale removal and application of supernatant of calcium cyanamide (CaCN₂) at 20%, gibberellic acid (GA₃) at 100ppm, and ethephon at 500 and 1, 000ppm on the termination of bud rest in single eye cuttings of ‘Muscat of Alexandria’ grape (Vitis vinifera L.). Bud scale removal greatly reduced the rest of cutting buds during the collection period from August 30, 1977, to February 28, 1978. In buds treated with CaCN₂, termination of rest was hastened during the period from August 30 to November 1, and then delayed gradually until December 27. The bud rest was broken naturally around January 30. Bud rest was markedly prolonged by GA₃ application during the collection period. Ethephon applied on November 30, when buds remained in a profound dormant condition, delayed termination of bud rest. These treatments were given to mature grapevines grown in a glasshouse. Appreciable increase in emergence rate was observed in the spring in both scale-removed and CaCN₂-applied buds.