Abstract
The effect of high temperature and/or gibberellin (GA) treatments during the early period of fruit development on the occurrence of watercore in Japanese Pear (Pyrus pyrifolia Nakai cv. Hosui) fruit was examined.
1. Trees or fruits covered with polyvinyl chloride film during the early period of fruit development yielded heavier fruits with smaller specific gravity, and higher incidence of watercore compared with the control fruits. The occurrence of watercore was especially severe in fruits covered with film.
2. When gibberellin was sprayed on the fruit surface or applied on the pedicel 30 days after full bloom, the fruits were heavier and softer with a smaller specific gravity compared with the control. GA treatment led to severe cases of watercore, especially when combined with the film treatment.
3. The fruit sprayed with paclobutrazol (PP-333), a gibberellin inhibitor, at 30 days after full bloom significantly suppressed the occurrence of watercore.
Thus, the occurrence of watercore is considered to be related to high temperature and gibberellin contents during the early period of fruit development in addition to the exposure to lower temperature during early summer.
