Use of gibberellins to improve fruit set in pears after frost damage

Abstract

The objectives of this study were to investigate the effect of applied bioregulators on fruit set after this frost in April 2002, growth, yield and the incidence of Pseudomonas syringae and the understanding of the underlying mechanisms of fruit set by applying bioregulators shortly after full bloom at the Klein-Altendorf experimental station near Bonn, Germany with the following results. The best fruit set was achieved with both GA3 and GA3 plus 0.51 GA4+7 sprayed at 12 mL ha-1 which increased initial fruit set by 78 and 77%, respectively as compared to unsprayed control with 32% while it was GA3 (105%) followed by the combination of GA3, Promalin and Azolon (100%) after June drop. The second-best fruit set was in GA3 plus 0.251 of GA4+7 and Azolon sprayed at 12 mL ha-1. Azolon reduced fruit set before and after June drop. Repeat applications of the treatments did not generally improve the results of fruit set after June drop. It is concluded that GA3 or combined with GA4+7, successfully improved fruit set, shoot growth, reduced the incidence of Pseudomonas syringae and rescued the yield showing that the mechanism is via development of parthenocarpic fruit. © 2008 Asian Network for Scientific Information.