Diversity Analysis of Fruit Phenotypic Traits in Camellia reticulata

Camellia reticulata is a valuable woody species prized for both its ornamental and oil-producing qualities. This study focused on four qualitative traits and nine quantitative traits of the fruits collected from nine wild populations and 30 cultivated varieties of C. reticulata. Multivariate statistical methods were employed to analyze the variation patterns of these fruits among populations and varieties, aiming to provide a scientific basis for the resource utilization and genetic improvement of this species. The results showed that the pericarp color clustered into two series: an orange-yellow (red) series (found in eight populations and all 30 cultivars) and a yellow-green series (unique to the Heiniu Mountain I population). The a* value was identified as the key indicator for distinguishing between these two color-series. The fruit shape was predominantly spherical, the seed shape was mostly hemispherical, and the seed coat color was primarily brown. Significant differences (p < 0.05) were observed among the nine quantitative phenotypic traits. Fruit weight exhibited the greatest variation (ranging from 28.499 g to 149.068 g), with particularly prominent differences among populations (Fengqing I was the heaviest at 149.068 g, while Yongping I was the lightest at 28.499 g). The coefficients of variation (CV) for phenotypic traits within populations ranged from 17.209% to 60.803% (mean 31.655%), and within varieties from 13.951% to 72.911% (mean 35.290%). Based on CV weights, seed weight showed the largest variation amplitude (21.342%) among populations, while seed number showed the largest variation amplitude (22.956%) among varieties. Correlation analysis revealed that all nine traits exhibited highly significant correlations across different populations and cultivars. Principal component analysis (PCA) indicated that the eigenvalues of the first two principal components were both greater than 1.00, with cumulative contribution rates reaching 73.570% for populations and 76.064% for cultivars, respectively. Cluster analysis grouped the studied materials into three clusters. The comprehensive evaluation identified the cultivar 'Lichan' as having the optimal performance (F = 2.410). Box plots revealed greater dispersion in seed number and pericarp thickness within wild populations, while cultivated varieties showed a wider distribution in locule number and fruit transverse diameter. Frequency distribution analysis demonstrated that all traits followed a normal distribution (R² = 0.673~0.999). Among them, fresh seed weight and fruit transverse diameter displayed obvious skewness. Furthermore, the variation in seed number was significantly higher in wild populations than in cultivars. This study reveals rich phenotypic variation in fruit traits between wild populations and cultivated groups of C. reticulata, with fruit size and seed number identified as key traits. These findings provide an important basis for the subsequent selection of hybrid parents and breeding of high-yield, high-oil varieties.