The experments were conducted in 1974 and 1976 to know the appropriate concentration of bezyl adenine(BA) applied as an additive to the prebloom treatment of gibberellic acid(GA) for improving the seedlessness ratio and compactness of Muscat Bailey A grape.
The treatment with GA alone at 200ppm resulted in consistently higher seedlessness ratio as compared to that at 100ppm. The additions of BA at 25, 50 and 100ppm tended to raise the ratio when GA was applied at 100ppm, but they did not affect it when GA was applied at 200ppm. Further, these treatments depressed the elongation of peduncle and rachis and increased the number of berries almost in proportion to the concentrations. As the results, the desirable compactness of bunch was gained at 25 and 50ppm.
Both berry weight and soluble solid content decreased due to the additions of BA only in the cases where berry set was improved by the treatments.
The appearance of abnormal berry, the details of which were reported in the previous paper, was not influenced by either the concentrations of GA or the combined applications of BA at any concentrations thoughit fluctuated obviously year by year.