Effect of Potassium Gibberellate on Growth and Development of ‘Black Corinth’ Grapes1

Abstract

Abstract ‘Black Corinth’ clusters at different stages of development were dipped into 25 ppm potassium gibberellate (KGA3). The most compact clusters resulted from treatment at 75% capfall or at succeeding applications up to 2 weeks after bloom. Most reduction in number of berries occurred at beginning of capfall and at 25% capfall. Berries treated between initiation of capfall and 1 week after full bloom were elongated while treatment at earlier or later stages resulted in round berries. The length-to-diameter ratio was greatest at 95% capfall and 3 days after full bloom. Clusters were treated with KGA3 at 0, 1, 2, 4, 6, 10, 20, 60, or 100 ppm at 75% capfall, 3 days, or 1 week after full bloom. At the 75% capfall stage, looseness and number of berries was decreased by KGA3 at 100 ppm Berry wt and vol were increased as compared to controls by all concn of KGA3 above 2 ppm. Length, diameter, and the length-to-diameter ratio generally increased progressively as the concn of KGA3 increased.