EFFECT OF GIBBERELLIN ACID TREATMENT CONCENTRATION AND TIMING ON THE FRUIT CHARACTERISTICS OF TRIPLOID GRAPE CULTIVAR, 'CHEONGYANG'

This study was designed to examine the effects of both the concentration and treatment time of gibberellin acid (GA3) on fruit quality in ‘Cheongyang’, a triploid grape. The first set of experiments were used to determine the optimal GA3 concentration (0 (water), 25, 50, and 100 ppm) and were completed when the flowers reached full bloom, with the final fruit characteristics evaluated following their harvest. These evaluations revealed that both fruit setting and enlargement increased with increasing GA3 concentration without any adverse side effects, revealing that GA3 at 100 ppm was the most effective concentration for these grapes. The effect of the time of GA3 treatment on fruit characteristics was evaluated by examining the major fruit indicators expressed when plants were treated with 100 ppm GA3 5 days before full bloom, at full bloom, and 5 days after full bloom. This confirmed that GA3 treatment at full bloom led to the largest fruit being produced with the least deterioration in fruit quality. Thus, our data suggests that applying GA3 at 100 ppm to flowers in full bloom will produce the most attractive seedless fruits in the triploid ‘Cheongyang’ grape cultivar.