Difference in Flowering Response between Mango ‘Aiko’ and ‘Irwin’

Abstract

Recently, mangoes are cultivated in various regions in Japan, but domestic cultivation still depends on one cultivar, ‘Irwin’. ‘Aiko’, a new cultivar bred in Kindai University, is characterized by larger fruits, less pulp fiber, later harvesting time than ‘Irwin’, and expected as an alternative cultivar to ‘Irwin’. As ‘Aiko’ has strong biennial-bearing tendency, it’s necessary to clarify flowering characteristics to establish a cultivation management suitable for ‘Aiko’. In this study, we investigated the effects of the previous year’s fruiting and the number of flushes on the proportion of reproductive shoot. Furthermore, the expression profile of MiFT gene was analyzed. The results showed that ‘Aiko’ has lower floral inducibility than ‘Irwin’, and that the previous year’s fruiting strongly influenced the proportion of reproductive shoot in ‘Aiko’. In both cultivars, the number of flushes was higher in unfruited branches than in fruited branches. The proportion of reproductive shoot in ‘Irwin’ was high regardless of the number of flushes, while that in ‘Aiko’ was higher for branches with more frequent shoot expansions. MiFT expression was hardly affected by the intensity of crop load and was higher in ‘Irwin’ than in ‘Aiko’. In ‘Aiko’, it was shown that it is important to secure a shoot that has flushed more than three times after pruning. Thus, the cultivation method like intentional biennial bearing method, in which productive and non-productive years are clearly distinguished, should be considered for ‘Aiko’.