Effects of GA-paste on the fruit set and the fruit growth of the persimmon (Diospyros kaki Thunb.)

Effect of painting treatment of GA-paste on fruit peduncle on the fruit set and the growth of Japanese persimmon cv. Hiratanenashi, Jiro and Fuyu was investigated. 1. Treatment of GA-paste on the young fruit after full bloom increased the fruit set. In cv. Hiratanenashi, treatment of GA-paste at 12 days after full bloom highly increased the fruit set, and GA-paste treatment at 24 days or 36 days after full bloom also increased the fruit set. In non-pollinated control plot of cv. Jiro and Fuyu, physiological fruit drop began at 1 to 2 weeks after full bloom and it's dropping occurred heavily at 3 to 4 weeks after full bloom, but it's dropping was prevented by the GA-paste treatment at 5 days after full bloom. Therefore, fruit set percentage of non-pollinated GA-paste plot was higher than that of non-pollinated control. In pollinated control plot of cv. Jiro and Fuyu, physiological fruit drop was a few, and it's dropping was much more prevented by GA-paste treatment. Therefore, the fruit set percentage of pollinated GA-paste plot was most high. 2. Treatment of GA-paste increased fruit size in an early stage of cv. Hiratanenashi Jiro and Fuyu, but had not effect on the enlargement of fruit in the latter stage. At harvest time, the fruit weight of GA-paste treatment plot at 24 days after full bloom of cv. Hiratanenashi was most heavy, but there was only small differences between GA-paste treatment and control. The fruit weight of cv. Jiro as not influenced by GA-paste treatment. In non-pollinated plot of cv. Fuyu, GA-paste treatment increased the fruit weight, but GA-paste treatment in pollinated plot had rather the only slight effect on the decrease of the fruit weight at harvest time. 3. Treatment of GA-paste didn't increased the fruit coloring in cv. Hiratanenashi and in non-pollinated pot of cv. Jiro and Fuyu. The fruit coloring in pollinated plot cv. Jiro and Fuyu was better than that in non-pollinated plot, and the soluble solids content in pollinated plot was higher than that in non-pollinated plot. Treatment of GA-paste in pollinated plot inhibited slightly the fruit coloring and reduced slightly the soluble solids content