Interspecific Cross Compatibility of Rhododendron in Changbai Mountain.

In order to explore the interspecific cross compatibility of Rhododendron and the feasibility of interspecific cross in germplasm innovation, reciprocal crosses among five species of Rhododendron in Changbai Mountain were made. In addition, the hybrid embryos were cultured in vitro. The results showed that the species of Rhododendron in Changbai Mountain had significant differences in reciprocal cross compatibility. When Rh chrysanthum Pall. was used as female parent, it showed high cross compatibilities with Rh. mucronulatum Turcz. (92.55%), Rh. mucronulamm Turcz. f. album Nakai (94.14%) and Yabuli Rhododendron (92.42%), and no significant differences were found in fruit setting rate by self-pollination. The germination rates of hybrid embryos were 13.60%, 11.59% and 4.12%, respectively. The hybrid seedlings had weak growth vigor and albino status and were trended to be aborted. After 2-3 generations of subculture, the growth vigor of hybrid seedlings were recovered gradually, and their differentiation rate was also significantly higher than that of Rh. chrysanthum Pall. seedlings. But the hybrid seedlings were still yellowish green. In reciprocal crosses, the fruit setting rates were significantly reduced. The combination with the highest fruit setting rate (36.51%) was Yabuli Rhododendron × Rh. chrysanthum Pall. The fruit setting rates of reciprocal crosses between Rh. chrysanthum Pall. and Rh. mucronulatum Turcz. and Rh. chrysanthum Pall. and Rh. schlip- penbachii Maxim were 6.52% and 0, respectively. However, the hybrid embryo’s germination rate (39.81%) of Yabuli Rhododendron × Rh. chrysanthum Pall. was significantly higher than that of their original cross. Moreover, the hybrid seedlings grew strongly and could be directly transplanted without subculture. [ABSTRACT FROM AUTHOR]