Abstract
Combined spraying of gibberellin (GA) and prohydrojasmon (PDJ) is an effective method of reducing peel puffing in satsuma mandarin fruit. However, there is a problem in that coloring of the fruit peel is delayed with the spraying. In the present study, the effects of spray concentrations and spray times of GA and PDJ on peel puffing and peel color were examined. Combined spraying of GA and PDJ at different concentrations was conducted from late August to early September in ‘Silverhill unshu’. Combinations of 1 ppm GA and 50 ppm PDJ, 3.3 ppm GA and 25 ppm PDJ, and 3.3 ppm GA and 50 ppm PDJ markedly inhibited peel puffing. The duration of coloring delay caused by these combined sprayings was more than 1 week. The combination of 1 ppm GA and 25 ppm PDJ also inhibited peel puffing. The duration of coloring delay caused by the combined spraying was almost within 1 week. Combined spraying of 5 ppm GA and 50 ppm PDJ for 3 cultivars, ‘Iwasaki wase’ (extremely early-ripening variety), ‘Okitsu wase’ (early-ripening variety), and ‘Silverhill unshu’ (mid-ripening variety), was also conducted at different spray times from August to October. The effects of the combined spraying on peel puffing and coloring delay were the highest with the spray time from the middle of August to late September in ‘Iwasaki wase’. In ‘Okitsu wase’ and ‘Silverhill unshu’, the effects of the combined spraying on peel puffing and coloring delay were the highest with the spray time in September.
