Effect of gibberellic acid and abscisic acid on fruit respiration in relation to final swell and maturation in persimmon

Effects of gibberellic acid (GA) and abscisic acid (ABA) on fruit respiration were investigated in relation to fruit growth and maturation in persimmon fruit. GA was applied 5 times during growth stage II at 100 ppm to whole branches bearing fruit, while ABA was applied once at 100 or 250 ppm to individual fruit before entering growth stage III. GA treatment delayed fruit coloring and softening and retarded final swell at growth stage III. Contrarily, ABA treatment promoted fruit coloration and slightly increased fruit growth. In connection with these effects, fruit respiration rate was reduced by GA treatment, while it was enhanced by ABA treatment. Furthermore, the respiration rise which occurred concurrently with the onset of growth stage III was retarded in GA treated fruit and advanced in ABA treated fruit. These results indicate that the high respiration rate observed during growth stage III have a close relationship to final swell and maturation of persimmon fruit. The respiration rise with the onset of growth stage III may be a key factor for inducing phase change from growth stage II to growth stage III.