Comprehensive evaluation of main fruit quality characteristics with 30

Abstract: 【Objective】The genus Actinidia comprises approximately 54 species and 21 varieties, in total 75 taxa, and most species are distributed in China. Among them, A. deliciosa, A. chinensis, A. arguta and A. eriantha have been successfully domesticated and cultivated. The cultivars of kiwifruit in China are diverse, but the fruit quality is uneven. Even if the same cultivar is planted in different areas, the fruit quality is also different. However, there is little knowledge of the comprehensive evaluation of fruit quality of cultispecies in different planting areas, and the comprehensive evaluation of several cultivars in the same planting area is scarce. Understanding the fruit quality traits of different cultivars can provide valuable information and assessment tools to breeders. Therefore, the objectives of this study were to investigate the variation in fruit quality of 30 kiwifruit cultivars (strains), and to carry out comprehensive evaluation of fruit quality.【Methods】A total of 30 kiwifruit cultivars (strains) were collected from kiwifruit germplasm resource garden in the management office of Three Gorges Botanical Garden, comprising 12 A. chinensis cultivars, 3 A. deliciosa cultivars, 2 A. arguta cultivars, 10 A. chinensis strains and 3 A. deliciousa strains (the strains are wild resources that were collected from Yichang city, Hubei province). To elucidate the fruit quality, we measured important fruit quality indicators such as fruit weight, fruit shape index, dry matter content, soluble solid content, vitamin C content, total sugar content and total acid contents. SPSS 23 statistical software was used for one-way analysis, principal component analysis (PCA), cluster analysis, and comprehensive score ranking to analyze and evaluate the fruit quality of different cultivars (strains).【Results】The results showed that the fruit quality traits of different kiwifruit cultivars (stains) were significantly different, with the coefficient of variation ranging from 10.95% to 53.89%. Among all the measurement indicators, the vitamin C content had the largest variation and the soluble solids content had the smallest variation. Three principle components with characteristic roots greater than 1 were extracted by PCA, and the cumulative contribution rate was 75.675%. The first principle component explained 41.909% of trait information that had high correlation with dry matter content, soluble solid content, total sugar content, total acid content, and sugar/acid ratio. The second principle component showed high correlation with fruit weight and fruit shape index could explain 19.904% of trait information. And the third principle component explained 13.863% of trait information that had high correlation with fruit weight, dry matter content and vitamin C content. According to the comprehensive score, the trend of fruit quality among 30 kiwifruit cultivars was as follows: Hongyang＞Cuiyu＞Wanhong＞Jinhong 50＞Jintao＞Miliang No. 1﹥ Donghong＞Guihai No.4＞SZ-07＞Jinyan＞Jinyang＞Mizao No. 2＞Kuilü＞Huayou＞SZ-54-1＞SZ-21＞SZ-15＞SZ-06＞Guichang＞Wuzhi No. 3＞Xianglü＞SZ-22＞SZ-11＞Jinnong＞SZ-47＞SZ-20＞SZ-13＞SZ-10＞SZ12＞SZ-14. The results of cluster analysis indicated that 30 kiwifruit cultivars (strains) could be clustered into five groups with Euclidean distance of 10. Group Ⅰ included 8 cultivars and 1 strain with the bigger fruit weight and higher dry matter content, soluble solid content and total sugar content; while group Ⅲ included 2 cultivars belonging to A. arguta with smaller fruit weight, higher dry matter content and sugar/acid ratio, lower vitamin C content and total acid content. Five cultivars with bigger fruit, higher dry matter content and fruit shape index, lower soluble solid content were clustered together (Group Ⅳ). The majority of cultivars were clustered into the above three groups. Group Ⅱ contained 1 cultivar and 7 strains, in which all the cultivar (strains) contained higher dry matter content and soluble solid content. Group Ⅴ comprised 1 cultivar and 7 strains, with higher total acid content, lower dry matter content, soluble solid content and sugar/acid ratio. The most of the strains were clustered into the Group Ⅱ and Group Ⅴ. And the results of cluster analysis were basically consistent with the results of PCA. Based on these findings, we concluded that Hongyang, Cuiyu, Wanhong, Jinhong 50, Jintao, Miliang No. 1, Donghong, Guihai No. 4, SZ-07 and Jinyan performed well in Yichang, Hubei province, while the fruit quality of Xianglü, SZ-22, SZ-11, Jinnong, SZ-47, SZ-20, SZ-13, SZ-10, SZ-12 and SZ-14 was poor.【Conclusion】The present research revealed that large variations in fruit quality were found among 30 kiwifruit cultivars (stains). Fruit quality comprehensive evaluation of kiwifruit was well evaluated by PCA combined with cluster analysis. It may therefore provide the theoretical basis for sustainable development of Yichang kiwifruit industry. However, the actual observation results of SZ-06 and SZ-15 were inconsistent with the comprehensive evaluation results, and more research should be conducted in the future. Moreover, pollen xenia also affected the quality of fruit, and we have conducted the study on the effect of pollen xenio on kiwifruit combined with the male plant breeding.