Relation of plant regulators to bud rest in Vitis vinifera grapes

A large varietal difference was noted in time required for grape buds to terminate rest. 'Pearl of Csaba' and seedless varieties terminated rest most rapidly. Exogenous applications of benzyladenine (BA) at 1000 ppm or of N-dimethylamino succinamic acid (B-9) at 2000 ppm hastened termination of rest. Benzothiazole-2(-oxyacetic acid (BOA) at 1000 ppm and 2-chloroethyltrimethylammonium chloride CCC) at 200 or 2000 ppm markedly delayed it.In cuttings of 'St. Emilion' treated with exogenous BA, much inhibitor disappeared from the treated buds within 10 days after treatment. We suggest that the effect of BA in terminating rest may be due to its destructive effect on inhibitor concentration in the bud.Inhibitory substances were present in buds from 'St. Emilion' from December 5 through the dormant season. The compounds disappeared and stimulatory activity increased at the start of shoot growth