Influence of Seeded Fruit on Seedless Fruit Set in Japanese Persimmon cv. Fuyu (Diospyros kaki L. f.).

Abstract

The influence of seeded Japanese persimmon cv. Fuyu (Diospyros kaki L. f.) fruit on the setting of seedless ones achieved by 1) hand-pollination; 2) open-pollination; 3) non-pollination; 4) ringing of the bearing shoot; and 5) gibberellin-3 (GA3) application was investigated to clarify the factors affecting seedless fruit set and the inconsistency of GA-treated fruit set.The number of seeds per fruit and the degree to which seedless fruit abscised on the same tree were significantly different among trees. However, a highly significant, positive linear relationship (r= 0.77) existed between the two parameters. No abscission of seedless fruits on ringed shoots occurred until the girdle region had healed. On non-pollinated trees, seedless fruit set increased as the concentration of GA3 was increased. However, more seedless fruit dropped from pollinated trees than from non-pollinated trees, although seedless fruits of both plots were treated with the same concentration. This induction of abscission is ascribed to the competition between seedless fruit and seeded fruit on the same tree. A major factor to fruit set was the competition among fruits; the competitive advantage of seeded fruit over parthenocarpic ones is the decisive factor whether or not GA-treated 'Fuyu' fruits abscise.