Effects of shoot variables and canopy position on fruit set, fruit quality and starch reserves of persimmon (Diospyros kaki L.) in subtropical Australia

The influence of canopy position (sectors: N, S, E, W; tree height: top, middle and base) and shoot growth on fruit set, yield and fruit quality of the non-astringent persimmon cultivar ‘Fuyu’ trained to standard modified central leader system was evaluated in subtropical Australia (Lat. 26°S). The main aim of the study was to determine if different sections of the tree canopy produce greater quantities of export-quality fruit. Light interception, net CO₂ assimilation, leaf nutrients, and starch were also measured for each canopy position. Generally, there was little or no effect of canopy position on fruit quality. In contrast, initial fruit set was highest in upper parts of the tree canopy exposed to higher irradiance. Weight of fruit removed from any position was primarily dependent on fruit set at that position. Fruit weight was poorly correlated (r < 0.30, n.s.) with leaf area, leaf number per fruit, shoot length, and shoot base diameter of fruiting shoots indicating that these variables are not useful criteria for determining thinning levels or final fruit size. The fruit disorder, calyx cavity, was least in the middle canopy. In contrast, average fruit weight, Brix, colour, texture and flavour were only slightly affected by canopy position. It was concluded from the study that, in Australia, light influences yield but not fruit quality. Export-quality fruit can be harvested from any position within the tree canopy.