Effects of Silver Ion on the Ripening of Japanese Persimmon Fruits

The effect of Ag+, applied in aqueous solution as AgNO3, on respiration, ethylene evolution and softening (three of ripening parameters) of Japanese persimmon (Diospyros kaki Thunb. cv. Fuyu) at various stages of development was studied at 25t. Immediately after the calyx portion was cut away from the fruit, various concentrations of Ag+ was vacuum-infiltrated through the scar of the fruit. The results were summarized as follows. In stage I fruits (harvested July 20), at 0.1 mM Ag+ inhibition was almost complete on all of three ripening parameters. At higher concentrations (0.5 mM and 2.5 mM), however, inhibition was far less on respiration and ethylene evolution than at 0.1 mM. On the contrary, fruit softening was accelerated at higher concentrations. In stage II fruits (harvested August 16), the inhibitory effect of 0.1 mM Ag+ on these three parameters decreased. In stage III fruits (harvested October 23 and November 13), 0. 02 mM Ag+ was effective on all of three parameters. On the other hand, 0.1 mM and 0.5 mM Ag+ accelerated the respiration, ethylene evolution and softening of the fruit.