Objective To Select the optimal parent and parental combination for improving breeding efficiency and maximize genetic gain in oil-tea hybrid breeding.

Method In this study, 11 fruit and oil related traits were detected in the intraspecific and interspecific hybrid progeny in nest design, including weight of single fruit, seed rate of fresh fruit, kernel rate of dry seeds, oil content of kernel and seven kinds of fatty acid content in the oil. The general combining ability (GCA) of female parent and special combining ability (SCA) of hybridized combination were analyzed. The genetic control modes for 11 traits were analyzed.

Result There were highly significant differences in 11 traits among 12 families. These differences mainly caused by paternal effects at the level of P < 0.01, and only the differences of stearic acid and linoleic acid content were affected by maternal effects at the level of P < 0.05. The GCA and SCA of the parents were comprehensively analyzed. The intraspecific hybridization ‘Changlin No.4’ × ‘Changlin No.23’ showed better combining ability in weight of single fruit, seed rate of fresh fruit, kernel rate of dry seeds, oil content of kernel and oleic acid content in oil. The interspecific hybridization of Camellia oleifera and C. meiocarpa ‘Changlin No. 53’ × ‘Xiao No.3’ had a better performance on weight of single fruit, palmitic acid, linoleic acid and linolenic acid content. The cross of ‘Changlin No. 53’ × ‘Xiao No.2’ had advantages in seed rate of fresh fruit, kernel rate of dry seeds, oil content of kernel and oleic acid content. The analysis of genetic effect showed that stearic acid, oleic acid and linoleic acid content were mainly controlled by additive genetic effect, while the other eight traits were mainly influenced by non-additive genetic effect. The heritability of 11 economic traits of per plant was greater than that of families. The breeding strategy of selecting excellent individual plants within the full-sib families should be adopted in the cross breeding of C. oleifera.

Conclusion The economic traits of C. oleifera are mainly controlled by inheritance, and less affected by environment. Weight of single fruit, seed rate of fresh fruit, kernel rate of dry seeds, oil content of kernel, palmitic acid, palmitoleic acid, linolenic acid and cis-11-eicosenoic acid content were mainly controlled by non-additive gene effect, and the influence of additive gene effect is relatively low. In interspecific hybridization, SCA evaluation of hybridized combination should be given priority. In this study, we explored the parental allocation and genetic effects of interspecific hybridization between C. oleifera and C. meiocarpa, which laid a theoretical foundation for guiding interspecific hybridization breeding of C.oleifera.