XIA Wenjuan, ZHENG Li, QIU Shouzhe, LIU Zhixin, YANG Shuo, FANG Jinbao, CHEN Delin, SUN Leiming

【Objective】This experiment aimed to investigate the genetic trends of fruit-related traits in the F1 generation of Actinidia chinensis‘Jintao’with different paternal parents, understand the influence of different paternal genotypes on the sex ratio, single fruit weight, soluble solids content (SSC), and flesh color of the F1 generation and try to screen out potential superior paternal parents.【Methods】 Using A. chinensis‘Jintao’as the maternal parent and 10 different male A. chinensis genotypes as paternal parents, 10 hybrid combinations were established. The sex ratio of the F1 generation was recorded, and fruit weight, soluble solids content (SSC), and flesh color were measured to analyze genetic trends and differences. Gray relational analysis (GRA) was applied for a comprehensive evaluation of fruittraits across the 10 hybrid combinations. At the harvest stage, 10 fruits were randomly sampled from each plant to measure single fruit weight and post- ripening SSC, while flesh color was visually described using the RHS color chart. Data were processed and statistically analyzed using Excel 2019, and GRA was also performed. SPSS 25.0 was used to calculate means, standard deviations, coefficients of variation (CV), chi- square values, and significance of differences.【Results】Among the 10 hybrid combinations, 8 exhibited male-biased sex ratio in the F1 generation, while 2 showed female-biased ratios. However, the differences between the male and female amount were not significant, comforming to a 1∶1 sex ratio. The average single fruit weight of the F1 generation ranged from 59.95 g to 79.84 g, all smaller than that of the maternal parent (82 g), with coefficient of variations (CV) of 18.75%- 26.00% . The top three combinations for average single fruit weight were I- 3, I- 8, and I- 2 (79.84 g, 79.34 g, and 74.51 g respectively), significantly or marginally bigger than the others. The combination I- 10 had the smallest average single fruit weight, only 59.95 g, significantly smaller than the most others. The maximum single fruit weight ranged from 85.42 g to 141.52 g among the 10 hybrid combinations, with a proportion exceeding the maternal parent ranged from 7.14% to 34.42%. Among them, I-8, I-3, and I-2 had the highest proportion of offspring surpassing the maternal parent (34.42%, 34.29%, and 30.77%, respectively). The average SSC of the F1 generation ranged from 12.9% to 16.1%, with CV of 9.14%-15.25%. Only three combinations surpassed the maternal parent in average SSC, while the other seven were lower. The combinations I-2, I-9, and I-5 had the highest average SSC (16.1%, 15.9%, and 15.7% respectively), significantly higher than the others. The combination I-10 had the lowest average SSC, only 12.9%. The maximum SSC across the 10 combinations ranged from 16.9% to 20.1%, with 8.33%-63.46% exceeding the maternal parent. The combinations I-2, I-5, and I-9 had the highest proportions (63.46%, 50.00%, and 46.51%, respectively). The flesh color of F1 generation showed a segregation of yellow, yellowish green, and light green, with yellow flesh being the most prevalent (41.18%- 84.21%), while yellowish green and light green proportions were nearly equal. The combination I-3 did not produce light green flesh phenotype. By assigning values to different flesh colors, the top three combinations in descending order were I- 7, I- 9, and I- 3. The gray correlation analysis of three traits revealed the following order of correlation and weight coefficients: SSC＞single fruit weight＞flesh color. The weighted relational degrees of 10 combinations ranked as: I-9＞I-3＞I-2＞I-7＞I-8＞I-5＞I-1＞ I-4＞I-6＞I-10.【Conclusion】The F1 generation exhibited extensive segregation in single fruit weight and SSC, with an overall trend toward smaller fruit size and lower SSC. The differential analysis revealed significant variations in these traits among the F1 generation of different hybrid combinations, suggesting that the observed differences might be attributed to the influence of the paternal parent. The flesh color also displayed distinct segregation, further indicating the paternal contribution to this trait. Based on the mean values of related traits and the proportion of F1 generation exceeding the maternal parent, it could be inferred that the paternal lines of I-8, I-3, and I-2 would possess potential for breeding large- fruit cultivars, while I-2, I-5, and I-9 would be more likely to produce offspring with high SSC. Furthermore, the paternal parents of combinations I-7, I-9, and I-3 may breed cultivars with yellow-flesh. The comprehensive evaluation results demonstrated that the paternal lines of combination I- 9, I-3, and I-2 seems to be more likely to breed new kiwifruit varieties with large fruit size, high soluble solids content, and yellow flesh.