The Effect of Removing Leaves, Flowers and Shoot Tips on Fruit-Set inVitis ViniferaL.

Abstract

Shoots of Muscat of Alexandria and Grenache grape vines growing in the field were girdled during flowering and treated by leaf and shoot tip removal to test the effect on fruit-set in the cluster. Set was directly proportional to the number of mature leaves and was reduced by the presence of immature leaves and the shoot tip. The results suggested that the needs of the shoot tip were satisfied before those of the cluster. Removal of the apical part of the shoot (topping) increased set but only if done when flower caps were falling. The removal of flowers on girdled shoots considerably increased percentage fruit-set, showing that lack of fertilization was not limiting set. The experiments suggested that fruit-set under these conditions was controlled primarily by the supply of metabolites to the cluster. This control may act through its effects on the developing seed. The role of hormones is not clear.