Effects of Flowering Time on Fruit Drop and Fruit Quality in Medium-late Ripening Citrus

Abstract

In this study, the effects of flowering time on fruit drop and fruit quality at harvest were investigated in 7 citrus (‘Seinannohikari’, ‘Harehime’, ‘Shiranuhi’, ‘Setoka’, ‘Tsunokagayaki’, ‘Reikou’, and ‘Aoshima unshu’). Flowers were classified into three groups according to the time of flowering: early-flowering (before full bloom), middle-flowering (at full bloom), and late-flowering (after full bloom). ‘Seinannohikari’ and ‘Tsunokagayaki’ had lower fruiting rates in the early-flowering group than the late-flowering group. For other cultivars, there were no significant differences in the fruit setting rate between the early- and late-flowering groups. The effects of flowering time on the fruit weight at harvest differed among cultivars. The weights of ‘Aoshima unshu’, ‘Tsunokagayaki’, and ‘Reikou’ fruits in the early-flowering group were significantly lower than those in the late-flowering group, whereas the weights of ‘Harehime’ and ‘Setoka’ in the early-flowering group were significantly higher than those in the late-flowering group. For ‘Seinannohikari’ and ‘Shiranuhi’, the fruit weight showed no significant difference among fruits of early-, middle-, and late-flowering groups. In ‘Aoshima unshu’ and ‘Reikou’, sugar and acid contents per fruit were lower in the early-flowering group than in the late-flowering group. In ‘Harehime’ and ‘Setoka’, the sugar content per fruit was higher in the early-flowering group than in the late-flowering group. In ‘Setoka’, the acid content per fruit was higher in the early- and middle-flowering groups than in the late-flowering group. In ‘Seinannohikari’, ‘Shiranuhi’, and ‘Tsunokagayaki’, time of flowering had no effect on the sugar or acid content per fruit.