EFFECT OF DEFOLIATION TIME ON DEPTH OF DORMANCY AND SUBSEQUENT VEGETATIVE AND REPRODUCTIVE DEVELOPMENT IN LOW-CHILL PEACHES

In a relatively low chill area (<50 chill hours) two varieties of peaches differing in chilling requirement viz ‘Flordaprince’ (150 hours) and ‘Flordagold’ (325 hours) were defoliated at 10 day intervals during mid-autumn.
When ‘Flordaprince’ was defoliated in early April, autumn bloom and leafing was induced within 60 days of defoliation.
In contrast to ‘Flordaprince’, April or May defoliation did not stimulate budbreak for ‘Flordagold’ trees, with buds appearing to enter dormancy in the normal manner.
For this cultivar, dose dependant responses of cuttings to hydrogen cyanamide throughout the dormant period were analysed in order to develop a dormancy index (DI). Examination of DI values showed early defoliation to reduce depth of bud dormancy throughout winter.
Despite buds on trees defoliated on early dates being in a less dormant state during winter, vegetative and floral budbreak was markedly delayed by early defoliation.
Thus, early defoliation exerts a dual effect on bud development of low-chill stonefruit:- both depth of dormancy and subsequent growth ability of buds are affected.

III International Workshop on Temperate Zone Fruits in the Tropics and Subtropics

J. Lloyd, D. Firth

https://doi.org/10.17660/ActaHortic.1990.279.25