Effects of Gibberellin and CPPU on Enlargement and Characteristics of Seedless Berries Induced by Streptomycin in the ‘Fujiminori’ Grape

Abstract

Effects of gibberellin (GA₃) and 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU) on enlargement of seedless berry induced by streptomycin (SM) in the grape cv.‘Fujiminori’ were investigated.
1. Seedless berries induced by SM were treated with the mixture of GA₃ 25 ppm and CPPU 5, 7.5 or 10 ppm. The higher the concentration of CPPU used, the heavier the cluster that was harvested. However, individual berry weight was less than 20 g.
2. The number of berries per cluster did not affect the promotion of berry size, in comparison with CPPU treatment. The best result was realized when berry thinning to about 23 berries per cluster was performed.
3. Enlarged grapes over 20 g were harvested when berries were sprayed by GA₃ 2.5 ppm at full bloom, followed by a mixture of GA₃ 50 to 100 ppm and CPPU 10 ppm 11 days later. The berries did not show any inferior effects such as pale skin color, lower sweetness and less acidity.