To breed novel Camellia oleifera cultivars characterized by spring flowering, superior fruit economic traits, and excellent oil quality, this study conducted a comprehensive evaluation of distant hybridization progeny, aiming to screen elite spring-flowering germplasm resources.

Twenty-seven initially selected spring-flowering superior individuals from the hybrid progeny of ‘Youza 2’ (YZ2) × ‘Deyou 2’ (DY2) served as experimental materials. Systematic observations were made on their flowering phenology, floral organ morphology, pollen viability, and fruit economic traits. Data were analyzed using correlation analysis, difference analysis, and principal component analysis.

Significant segregation in flowering traits was observed among the 27 spring-flowering Camellia oleifera superior individuals. The earliest initial flowering date occurred in YD21, while the latest was recorded for YD11. YD26 exhibited the longest full-bloom period, lasting 32 days. Floral organ traits showed varying degrees of variation among individuals, with style number ranging from 3 to 5 lobes and petal number ranging from 5 to 10. Notably, YD22 displayed the largest flower diameter (89.56 mm), consistent with entomophilous characteristics. Correlation analysis revealed highly significant positive correlations (P<0.01) between petal number and style number, and between flower diameter and style length, indicating coordinated regulation in floral organ development. Pollen viability varied markedly among individuals, ranging from 35.35% to 83.31%. YD17 demonstrated the highest pollen viability (83.31%), and the phenomenon of “pseudo-pollen” was observed. Regarding fruit traits, YD6 possessed the thinnest pericarp (1.32 mm), with its fresh seed yield rate (52.99%) and kernel oil content (51.17%) being significantly superior to parental performance. YD17 exhibited the highest fresh seed yield rate (63.31%), standing out prominently among the population. Unsaturated fatty acids accounted for 85.40%-88.01% of the total fatty acids in the oil. YD11 displayed the highest oleic acid content (79.77%).

Comprehensive evaluation identified superior individuals YD3, YD7, and YD17 as outstanding performers for key economic traits, including fruit size, seed yield rate, and oleic acid content. These individuals represent valuable germplasm resources for further breeding and research.

To explore the photosynthetic characteristics and leaf morphological structure of Camellia oleifera hybrid offspring and provide a theoretical basis for the selection and breeding of high-light-efficiency camellia germplasm.

35 offspring were initially selected as test materials from the offspring groups of ‘Youza 2’ and ‘Huaxin’. Determination of photosynthetic characteristics and morphological structure of leaves of hybrid offspring. And use analysis of variance, correlation analysis, clustering analysis, principal component analysis and other methods to compare, analyze and evaluate the photosynthetic characteristics and morphological structure of leaves

The net photosynthetic rate, stomatal conductance, transpiration rate, and water use efficiency of offspring individuals varied greatly, and the coefficients of variation of the four indicators were all higher than 20%. There were significant differences in the chlorophyll and carotenoid contents of the offspring individuals, and the coefficients of variation were all higher than 10%; 2) The leaf area, cuticle thickness, upper epidermis thickness, and ratio of palisade tissue to spongy tissue had large variations, with coefficients of variation ranging from 15.36% to 19.66%, among which the coefficient of variation of the ratio of ratio of palisade tissue to spongy tissue was the largest at 19.66%; 3) The correlation results showed that all 10 indicators of leaf photosynthetic characteristics were correlated; the net photosynthetic rate was strongly correlated with stomatal conductance and transpiration rate, and the stomatal conductance was strongly correlated with transpiration rate. The transpiration rate was strongly correlated with water use efficiency; the thickness of palisade tissue was positively correlated with net photosynthetic rate, chlorophyll content, and transpiration rate; 4) The results of K-means cluster analysis showed that the water utilization rate of group I was high, but the light energy utilization efficiency and photosynthetic potential were low; the leaves of group II were the thickest, and the various tissue structures of the leaves ranked higher, with strong water retention capacity and disease resistance; the number of stomata per unit area of leaves in group III was large, and the gas exchange capacity was strong; the light energy utilization efficiency and photosynthetic potential of group IV were higher; 5) The results of principal component analysis of photosynthetic characteristics showed that among the 35 hybrid progeny the top three in terms of comprehensive scores were YX-63, YX-47 and YX-115. YX-63 had the highest comprehensive score and the best photosynthetic performance.

There were rich variations in leaf photosynthetic characteristics and morphological structures among hybrid offspring; YX-63, YX-47 and YX-115 had higher light energy utilization efficiency and photosynthetic potential.