Effect of Defoliation Time on Depth of Dormancy and Bloom Time for Low-chill Peaches

Abstract

In a relatively low-chill environment, two cultivars of peach [Prunus persica (L.) Batsch] differing in chilling requirement (`Flordaprince', 150 units and `Flordagold', 325 units) were defoliated at 10-day intervals during midautumn. Effects of defoliation on depth of bud dormancy and dose-dependent responses of cuttings to hydrogen cyanamide throughout the dormant period were analyzed to develop a dormancy index (DI). DI values indicate that early defoliation reduces depth of bud dormancy throughout winter for both cultivars. For `Flordaprince', this was translated into early leafing and bloom, but fruit size was reduced by early relative to late defoliation. In contrast to `Flordaprince', vegetative and floral budbreak of `Flordagold' were delayed by early defoliation. These results indicate that early defoliation affects depth of dormancy and growth ability of buds, but that the extent to which these factors affect bud development depends on cultivar.