ADVANCEMENT AND DELAY OF THE MATURATION OF NON ASTRINGENT PERSIMMON FRUITS WITH GROWTH REGULATORS

The persimmon (Diospyros kaki L.) industry in Israel is based almost solely on one cultivar — the ‘Triumph’. This situation makes problems in marketing the fruit production in a limited period. To overcome this problem various Japanese cultivars of persimmon have been introduced to Israel. ‘Shinshu’ was found to be the earliest cultivar and ‘Late Fuyu Mutant’ the latest one of the production season. PGRs have been used for manipulating the timing of the fruit maturation by advancing the early season and delaying the late season cultivars. Dormex (hydrogen cyanamide, 2%), applied on the cultivar ‘Shinshu’ 45 days before boom, advanced the flowering time by 18 days but had less of an advancing effect on the picking time. Uniconazol [(E)-1-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol], a gibberellic acid bio¬synthesis inhibitor, applied at full bloom, advanced the fruit maturation of ‘Maekawa Jiro’ and improved the fruit size of ‘Jiro’. The cytokinin-like regulator CPPU [N-(2-Chloro-4-pyridyl)-N’-phenyl urea] retarded the fruit maturation of the late season cultivar ‘Late Fuyu Mutant’. It seems that the persimmon production season could be potentially extended by introducing new appropriate cultivars and by advancing and delaying maturation following PGRs application.