Effects of fruit thinning, pollination and paclobutrazol on fruit set and size of persimmon (Diospyros kaki L.) in subtropical Australia

A factorial combination of three cultural factors (± hand-pollination, ± growth retardant, ± fruit thinning) were evaluated for their effects on fruit set and fruit size of ‘Fuyu’ persimmon (Diospyros kaki L.) in subtropical Australia (Lat. 27° S). Treatments were applied to individual shoots on mature seven year old trees. Fruit set of pollinated flowers was high compared with non-pollinated flowers (91% vs. 47%). Pollinated fruit also grew faster at all stages of fruit development and, at harvest, fresh weights were 25% heavier. Palcobutrazol significantly (P < 0.05) increased fruit weight by 7% compared with controls but did not increase fruit set. Irrespective of treatment, fruit weight was not correlated (r < 0.3, n.s.) with shoot length, number of nodes per shoot, fruit nodal position, shoot dry weight, leaf area per shoot, and number of leaves per shoot. Fruit fresh weight was only poorly correlated with shoot base diameter (r = 0.41*). Pollinated fruit had significantly (P < 0.05) higher concentrations of nutrients (N, K, Ca, and Zn).