Inter-specific and Inter-generic Hybridization Compatibility of Eriobotrya Species (Loquat) and Related Genera

We studied the cross-compatibility among 91 inter-specific combinations and 21 inter-generic combinations in 7 Eriobotrya plants and 2 related genera(Raphiolepis indica Lindl. and Photinia serrulata Lindl.) using emasculation, bagging, and artificial pollination. Our results showed that28 of the 91 inter-specific combinations set no fruit, which means nearly 30% of the combinations were incompatible. In the remaining 63 combinations, most showed partial cross-compatibility, and a few showed complete cross compatibility. Eriobotrya plants were incompatible with plants from their related genera(R. indica Lindl. and P. serrulata Lindl.). Backcrossing produced 5 compatible combinations, which could set fruits and produce F1 progeny but only after embryo rescue. Fruit setting ratios varied among various species used as male or female parents.E. prinoides Rehd. & Wils., common loquat(E. japonica) and Eriobotrya × daduheensis, used as female parents resulted in an average fruitsetting ratio of 36.2%–58.2%. E. deflexa Nakai and its two forms, and E. elliptica Lindl. as female parents resulted in 2.9%–16.3% average fruitsetting ratio; however, the fruit set ratio was higher(22.4%–43.1%) if they were used as male parents. Failure of E. deflexa f. koshunensis Nakai × E.prinoides Rehd. & Wils. hybrids to set fruit could be attributed to sporophytic incompatibility.