EFFECTS OF TOPICAL POSTHARVEST APPLICATIONS OF 6-PENTYL-2-PYRONE ON PROPERTIES OF STORED KIWIFRUIT

The effects of treating picking wounds of kiwifruit (Actinidia delicio sa) at harvest with 6-pentyl-2-pyrone (6PP, a fruit fragrance compound , also produced naturally by Trichoderma species, and used to prevent Botrytis cinerea rots) on the properties of stored kiwifruit were inve stigated. Firmness of treated fruit was no different from that of cont rols when stored at 0 degrees C for up to 8 months. On restoration to ambient temperature (18 degrees C), treated fruit stored at 0 degrees C for 4 months or longer softened at a rate similar to that of control fruit, but treated fruit stored 2 months or less softened significant ly more rapidly. 6PP caused freshly formed picking wounds to become ne crotic. Residues of 6PP that had been applied to the picking wounds de clined with a half-life of about 26 days at 0 degrees C, and more rapi dly where 6PP was applied directly to fruit slices. Higher residues oc curred for 6PP applied to other external surfaces. Although only trace residues of 6PP were recovered from internal tissues, comparison with the persistent fungicide vinclozolin suggests that significant 6PP wa s absorbed into the fruit and subsequently degraded. The accelerated r ipening of treated kiwifruit was attributed to a phytohormonal or phyt otoxic effect of the 6PP at ambient temperatures. (C) 1997 Elsevier Sc ience B.V.