Effects of long-day treatment at different light intensities on maturation and fruit quality in Japanese persimmon 'Saijo'

Abstract

To delay harvest of Japanese persimmon 'Saijo' (Diospyros kaki Thumb.) grown under a greenhouse, the effects of a long-day photoperiod at different light intensities on tree growth and fruit quality were tested. Exposure of 'Saijo' trees to intensive light from August 27 to December 8 under 17 ± 1 hr photoperiod with white fluorescent lamps increased leaf color (SPAD value), secondary shoot growth, and the flesh firmness of the fruit while delaying leaf abscission, fruit color development and decreasing soluble solids content (Brix). These results indicate that the long-day treatment somehow caused delay in fruit maturation and enhances vegetative growth in 'Saijo'. The optimum value of photon flux density (PFD) on the canopy surface was estimated to be 1.5 μmol · m-2 · sec-1 to delay harvest of 'Saijo' by approximately 25 days.