To study the phenotype of disease-resistant superior plants in the offspring of ‘Youza 2’ × ‘Haiyou 3’, so as to provide a theoretical basis for the study of genetic variation of interspecific hybridization and the cultivation of excellent germplasm of Camellia oleifera.

Ten disease-resistant and superior strains were selected from the F₁ generation of Camellia oleifera with ‘Youza 2’ as the female parent and ‘Haiyou 3’ as the male parent, and their flower phenotypes were determined. Among the 10 excellent disease resistant plants, six of them were fruited, and their fruit phenotype and economic quality traits were determined and analyzed, and the scores were calculated by principal component analysis, and the optimal plants were selected.

1) The flowering period of the 10 resistant plants and their male parent ‘Haiyou 3’ was in winter, and the flowering period of the female parent ‘Youza 2’ was spring, and the flowering period of the hybrid offspring was earlier than that of the male parent. The coefficient of variation of the 11 measured indexes, including floral appearance and pollen characteristics, ranged from 2.98% to 17.47%; 2) The coefficient of variation of 26 measured fruit appearance, economy and quality traits among hybrid offspring ranged from 6.51% to 57.71%; 3) Principal component analysis was performed on 14 indexes, including single fruit weight, fruit transverse and longitudinal diameter, peel thickness, etc., and two principal components were extracted, with a cumulative contribution rate of 88.86%. The comprehensive ranking of 6 disease resistance results of the hybrid offspring was YH-10>YH-7>YH-2>YH-5>YH-4>YH-1, of which YH-10 has the highest comprehensive score of 3.17.

After cross-breeding with ‘Youza 2’ as the female parent and ‘Haiyou 3’ as the male parent, the F₁ generation of disease-resistant superior plants was rich in phenotypic variation among plants, and the F₁ generation produced a disease-resistant large-fruited superior plant YH-10 with excellent traits of both parents (disease resistance and fruit economic traits significantly higher than those of the low parents), and its single fruit weight increased by 41.65 g compared with that of the female parent.