Japanese plum pollination: A review

Abstract

The reproductive behavior of Japanese plum has not been studied as in other Prunus species. Thus, a number of cultivars are particularly prone to erratic fruit set showing low yield for reasons that are not clear. Traditionally, the factors related to pollination have not been considered as causes of low yield in this crop, but in the last years lack of fruit set was recorded in different cultivars due to reproductive failure. Japanese plum, like other Prunus fruit tree species, is self-incompatible and requires cross pollination to ensure fruit set because this genus is unable to bear fruit parthenocarpically. Therefore, knowledge of pollination requirements of cultivars is essential to solve problems of low yield related to lack of pollination and for new orchard plantation plan with adequate proportion of pollinizers. The incompatibility relationships between Japanese plum cultivars have not been studied comprehensively until the last decade. An important amount of information has been revealed in this period, since a high number of commercial cultivars are currently available and new cultivars are being obtained from different breeding programs. In this article, the information available on the reproductive process in Japanese plum is reviewed, paying special attention to pollination factors and incompatibility relationships between cultivars. The S-RNase genotype of 222 cultivars compiled herein, allocated in 26 Incompatibility Groups, five of them described for the first time, will be valuable for fruit growers to choose adequate pollinators in commercial orchards, and for breeders to choose parental genotypes and select offsprings in breeding programs.