Delay of fruit softening in forcing-cultured 'Tonewase' Japanese persimmonby packaging in perforated polyethylene bags

'Tonewase' is an early maturity strain selected from 'Hiratanenashi', an as tringent Japanese persimmon cultivar. In some districts of Japan,'Tonewase' has been grown under forcing-culture conditions, which often results in ra pid softening during postharvest distribution. In this study, we elucidated that this softening is caused by water-stress-induced ethylene that can be suppressed by reducing water loss by using perforated polyethylene bags (P PB). With or without removal of astringency by treatment with elevated carbon di oxide (CTSD method), forcing-cultured 'Tonewase' fruit produced significant amounts of ethylene two days after harvest; thereafter, most fruit softene d rapidly. This softening was markedly suppressed by treating the fruit wit h 1-methylcyclopropene (MCP), an inhibitor of ethylene action, which sugges ts the involvement of ethylene in fruit softening. Packaging 'Tonewase' fru it in PPB ranging from 0.03% to 0.3% of the total film surface area reduced water loss, retarded the commencement of ethylene production and delayed f ruit softening. Immature field-grown 'Hiratanenashi' fruit behaved similarl y to the forcing-cultured 'Tonewase' fruit with respect to ethylene product ion, softening and response to MCP treatment and PPB, whereas mature fruit under the same storage conditions produced no ethylene and remained firm du ring postharvest.