Full compatibility is superior to semi-compatibility for fruit set in Japanese plum (Prunus salicina Lindl.) cultivars

Japanese plum belongs to the Rosaceae, which carry the S-RNase-based gametophytic self-incompatibility system. Therefore, these plum cultivars depend on cross-pollination for setting fruit. However, cultivar combinations may be genetically semi- or fully compatible. In apples and pears cultivated in Israel, where conditions for pollination are usually unfavorable, it was demonstrated that yields may be correlated with compatibility levels of pollinators. In the present study fruit-set of semi- and fully compatible plum couples was determined for a wide range of cultivars, in unfavorable and favorable conditions. Full compatibility was found superior to semi-compatibility, in both unfavorable and favorable conditions for pollination. These findings should be taken into consideration in determining the orchard designs of cultivars.