Relationship between Fruit Softening, Ethylene Production and Respiration in Japanese Persimmon 'Hiratanenashi'.

Abstract

The relationship between fruit softening, ethylene production and respiratory activity in the Japanese persimmon (Diospyros kaki Thunb.) was studied to investigate the role of ethylene. The effects of ethanol treatment on ethylene production and flesh softening were studied concurrently. 1. At every stage of fruit development, increases in ethylene and carbon dioxide evolution by the harvested fruits were observed even though fruits were still firm. Ethylene evolution either preceded or coincided with a rise in the repiration rate, independent of fruit maturity. 2. Ethylene production increased rapidly 24 hr after ethanol treatment, whereas the flesh began to soften after 48 hr. The higher the concentration of ethanol, the faster were the rates of ethylene evolution and fruit softening. The alcohol treatment, which removes astringency, also hastened the abscission of the calyxes as compared with the untreated control fruits. 3. Carbon dioxide, which is also used to remove astringency, depressed the rates of ethylene evolution and respiration and delayed the rate of fruit softening, as compared with the untreated control fruits. These results suggest that ethylene is probably an activator of the mechanism which leads to fruit softening in the Japanese persimmon 'Hiratanenashi'.