RELATIONSHIP BETWEEN SEED DEVELOPMENT AND LATE-SEASON FRUIT CRACKING OF 'KOJONGSI' PERSIMMON

‘Kojongsi’, an astringent Korean native, has been one of the most popular cultivars used for the production of dried fruits. However, at a major growing area, the fruit often cracks during the late season. The cracking begins from the calyx, resulting in the decrease of the yield and the increase of fungal infection during drying. In this study, we monitored the relationship between seed development and the occurrence of this disorder. Two variables for seed development included (a) artificial- or non-pollination and (b) the presence or absence of pollinizers. The non-pollination treatment was done by screening visiting insects. Three percent of the fruits were seedless in pollinated trees, in sharp contrast to 100% in non-pollinated counterparts. Fruits from the trees with pollination cracked 0%, while those with non-pollination did 88%. The orchards with and without pollinizers produced 15.3 and 100% seedless fruits, respectively, 5.9 and 29.2% of which were cracked. Results strongly suggested that the inhibition of normal seed development was related to the occurrence of this disorder. Management to ensure good pollination may be an essential prerequisite to reduce the late-season cracking of this cultivar.