Objective To explore genetic variation patterns in growth-phenotype traits of Cyclobalanopsis gilva families at the seedling stage, and select elite families with superior early growth performance.

Method Fifty-nine natural excellent C. gilva plants were selected from Jianou City and Zherong County, Fujian Province, seeds were collected, and seedlings were cultivated. Seedling height, leaf number, leaf length, leaf width, leaf aspect ratio and leaf area were measured and calculated. Analysis of variance, heritability estimation, correlation analysis, and principal component analysis were conducted, and the principal component comprehensive scoring model was constructed to rate the tested families.

Result At the seedling stage, seedling height, leaf number, leaf length, and leaf area showed significant differences among families and in the family × replication interaction, while leaf width and leaf aspect ratio showed significant differences among families. The family heritability of growth-phenotype traits ranged from 0.793 to 0.905, indicating moderate to high genetic control of growth traits at the family level and substantial potential for genetic improvement through early selection. Correlation analysis results showed highly significant correlations among traits, with the strongest correlation between leaf width and leaf area. Among the correlation coefficients between seedling height and other traits, that with leaf number was the strongest. Principal component analysis showed that the first two components accounted for 82.838% of the cumulative variance. A comprehensive scoring model was developed based on these two components. Totally 20 families with excellent growth performance were selected from 59 families with a selection rate of 33.9%. The average genetic gains of seedling height, leaf number, leaf length, leaf width, leaf aspect ratio and leaf area for these 20 families were 20.22%, 18.89%, 13.01%, 8.34%, 3.44% and 21.27% respectively.

Conclusion There are abundant genetic variation in growth-phenotype traits of C. gilva families at the seedling stage, and the growth-phenotype traits show significant or highly significant differences among families. The performance of growth-phenotype traits is subjected to moderate to high genetic control. Twenty families with excellent growth performance have been preliminarily selected. Superior seedlings from these families can be used for cutting propagation studies to promote their application through asexual propagation.