Effects of pollination and irradiance on fruiting of persimmon(Diospyros kakiL.) in subtropical Australia

Three experiments evaluated the effects of pollination and irradiance on fruit set, fruit drop, and fruit size and weight of ‘Fuyu’, the most highly planted non-astringent persimmon cultivar in subtropical Australia (Lat. 27° S). At irradiances of 13.8 and 5.9 vs. 19.8 MJ m~2 day"1, fruit set of open.pollinated flowers was reduced by 53 and 100%, respectively. In contrast, fruit set of hand pollinated flowers was reduced by only 21 and 40%, respectively. Fruit weight of open pollinated or non-pollinated fruit was between 5-20% lower than hand pollinated fruit. Whole tree or calyx shading slightly reduced fruit size of hand pollinated fruit. The planting of adequate numbers of pollinizer trees and the provision of hives of European honeybees might be essential for adequate set and fruit size in coastal regions of Australia which experience cloudy conditions (irradiance < 10 MJ rrf2 day"1).