STUDIES ON THE POSTHARVEST PHYSIOLOGY OF SUGAR APPLE

The fruits stored at 16°C for 14 days were only partially ripened. No respiratory climacteric peak was found during the storing period, and the total soluble solid (TSS) increased gradually to 9° Brix. The fruits stored at 20°C ripened and softened completely within 6 days, the TSS increased very quickly to 24° and the respiration rate reached a peak at the 8th day after harvest. The fruits stored at 28°C ripened within 4 days after harvest and the TSS reached a high level of 22°. Storaging at 16°C keeps the quality of the fruits better than those stored at higher temperatures.

The ethylene evolution was enhanced by ACC (1-aminocyclopropane-1-carboxylic acid) and inhibited by AVG (aminoethoxyvinylglycine) treatment. Controlled atmosphere storage delayed the ripening of the fruits and also inhibited the evolution of ethylene.

Endogenous IAA-like substance contents reached a peak when the fruits ripened, and preceded the ethylene peak by one day. It seemed that the increase in endogenous IAA is closely related to the ripening of the fruits. No autocatalystic generation of IAA was detected by IAA treatment.