Multivariate statistical analyses of fruit characteristics of wild kiwifruit germplasm resources in different ecological regions of Yunnan

Abstract:【Objective】Yunnan province is located in the southwest frontier of China, with rich and diverse climate types, which provide different ecological environment and living conditions for different kinds of kiwifruit, so that Yunnan province is enriched with kiwifruit resources. At present, some related studies such as sensory traits, morphological indicators, nutrient contents and nutritional quality have been carried out on kiwifruit resources in Yunnan. In order to find out the genetic differences and genet-ic diversity, provide reference for future genetic breeding of kiwifruit, guide the screening of new germplasm and accelerate the research and utilization of germplasm resources of the genus kiwifruit in Yun-nan, we surveyed and collected local wild kiwifruit germplasm resources in Yunnan from 2019 to 2021,and investigated the genetic differences, taxonomic status, and correlations among the 12 traits exam-ined, which were based on the morphological identification analysis, by conducting multivariate statistical analysis of fruit traits in 76 wild kiwifruit germplasm resources collected from five regions in north-eastern, southeastern, southern, northwestern, and eastern Yunnan.【Methods】Multivariate statistical analyses, such as variation analysis, factor analysis, correlation analysis and cluster analysis, were per-formed on 12 fruit traits including fruit shape, longitudinal diameter, transverse diameter, side diameter,fruit shape index, single fruit weight, fruit skin color, fruit dots, hair density, hair type, flesh color and flavor of 76 Yunnan kiwifruit germplasm resources.【Results】The coefficients of variation of 12 traits ranged from 23.96% to 117.01%, and among the traits, the largest coefficients of variation were hair  type and hair density, with coefficients of variation of 117.01% and 113.49%, respectively. Morphologi-cal identification analysis showed that 76 Yunnan wild kiwifruit germplasm resources were with all kinds of hair type, for example, some fruits were densely covered with short woolly hairs, some fruits were densely covered with long woolly hairs, some fruits were densely covered with rough hairs, and some fruits were hairless. The coefficients of variation of flesh color, fruit weight, fruit shape and fruit dots were larger, exceeding 50%, by 78.57%, 67.94%, 62.52% and 51.90%, respectively. Morphologi-cal identification analysis showed that 76 Yunnan wild kiwifruit germplasm resources possessed all kinds of flesh color, fruit weight and fruit shape. However, many types had fruit dots, while some of them did not have obvious fruit dots. Six traits whose coefficients of variation were below 50% were longitudinal diameter, transverse diameter, side diameter, skin color and flavor, and the smallest coeffi-cient of variation was flavor. Morphological identification analysis showed that most germplasm resources had sweet flavor, a small part of germplasm resources had sour flavor, and a small part of germ-plasm resources had a slightly sour flavor. Factor analysis yielded three main factors with a cumulative contribution of 73.843%. Factor 1 had high loading value of 0.948 and 0.935 for transverse diameter and side diameter, respectively, which can be called the fruit weight factor, and transverse diameter and side diameter were closely related to the fruit weight. Factor 2 had a maximum loading value of 0.74 for fruit shape index, which can be called the fruit shape factor, and shape index was closely related to the appearance of fruit. Factor 3 had larger loading value of 0.689 and 0.551 for fruit dots and fruit shape, respectively, which can be called the appearance factor, and fruit dots and fruit shape were related to the appearance of fruit. The results of correlation analysis showed that 25 pairs of traits were highly signifi-cantly and positively correlated with each other, 7 pairs of traits were highly significantly and negative-ly correlated with each other, 3 pairs of traits were significantly and positively correlated with each oth-er, and 5 pairs of traits were significantly and negatively correlated with each other. Through cluster analysis, the 76 germplasm resources collected from five different geographical regions in Yunnan prov-ince could be classified into three major categories. The first category included 38 materials with the shortest longitudinal diameter, transverse diameter and side diameter, and the smallest weight per fruit and minimum fruit, most of which are hairless dotted fruit unsuitable for materials of dotused to breed fresh-eating varieties. The second category included 28 materials with the moderate longitudinal diame-ter, transverse diameter and side diameter, most of which were covered with long woolly hairs and the weight per fruit was nearly 30 g. The third category included 10 materials with the longest longitudinal diameter, transverse diameter and side diameter, and weight per fruit were the largest with the weight per fruit being nearly 50 g. Morphological identification analysis showed that most of resources were sweet and delicious with smaller value of hair density and they were suitable for materials used to breed medium fresh-eating varieties.【Conclusions】This study showed that there were significant genetic dif-ferences and rich genetic diversity among the fruit traits of 76 wild kiwifruit germplasm resources from different ecological regions of Yunnan, and this study can provide reference for future genetic breeding of kiwifruit, guide the screening of new germplasm and accelerate the research and utilization of germ-plasm resources of the genus kiwifruit in Yunnan.