Preliminary Study on the Breeding System and Crossbreeding of Rhododendron maxiongense (Ericaceae)

Purpose To provide the theoretical basis for the protection and landscape application of Rhododendron maxiongense.

Method In this study, flowering phenology and visiting insects were observed, and the indices of hybridization, pollen ovule ratio and controlled pollination were counted.

Result The flowering phase of R. maxiongense is from middle April to the end of May, and the hybrid index (OCI)≥4, P/O ratio is 422.48; the main pollinators is Apis cerana. The highest fruit rate of R. maxiongense was 57.14% under the natural conditions, and the fruit rates of the cross pollination in the same or different individuals were only 24.28% and 17.14%. Moreover, the fruit rates of artificial cross between R. maxiongense (♀) and R. delavayi (♂) , R. decorum (♂) , R. irroratum (♂) and R. molle (♂) were 11.43%, 22.86%, 2.86% and 10%, receptively.

Conclusion The results revealed that the best period of pollen activity and the stigma receptivity of R. maxiongense may not meet each other; the breeding system is facultative outcrossing, self-compatibility, and require pollinators; the pollinator efficiency is highest under the natural condition, and the low rates of artificial pollination in the same species and between different species, because it was difficult to grasp the best period of the pollen activity and stigma receptivity.