Genetic diversity analysis of main agronomic traits in yam germplasm resources

【Objective】The genetic diversity, genetic relationship and classification characteristics of agronomic traits in different yam germplasm resources collected from different regions of China were analyzed in order to provide references for variety breeding and production utilization of yam. 【Method】The 19 agronomic traits of 44 collected yam germplasm resources were investigated to conduct genetic diversity analysis, cluster analysis and principal component analysis for exploring their genetic diversity, genetic relationship and classification characteristics. 【Result 】The results showed that different morphological traits of 44 collected yam germplasm resources presented higher diversity. Amongst 12 qualitative traits, the genetic diversity index of leaf shape was the highest(1.53), followed by tuber skin color(1.51). The frequency distribution of tuber shape was the highest(93.18%), followed by tuber flesh color(90.91%) and stem shape(81.82%). Amongst 7 quantitative traits, the genetic diversity index of tuber length was the highest(1.89), followed by growth duration(1.84) and tuber diameter(1.77). Among different traits, the variation coefficient of yield per plant was the highest(79.25%), followed by tuber diameter(42.21%) and tubers per plant(35.62%), the lowest was found to be growth period(17.57%). According to genetic differences of different agronomic traits, 44 yam germplasm resources could be clustered into 4 groups. All the materials of the first and second groups were derived from Guangxi, and could be used as processing parent materials with potential of increasing yield, and high-yield variety breeding parents, respectively. The third group materials were mainly derived from southern China, which was artificial cultivation wild species and could be used as general parent. And the fourth group materials were derived from north provinces of China and could be used as common early-maturing variety breeding parents. The principal component analysis results indicated that the contribution rate of the first 6 principal components accounted for 83.73%. The first principal component reflected comprehensive factors of high-yield plant type, the second one reflected processing plant type factors, and the third one reflected plant tuberization factors. The fourth, fifth and sixth principal components reflected tuber factor, tuber skin and stem skin color, respectively.【Conclusion 】The agronomic traits amongst landraces of yam cultivars germplasm resources in China presented significant differences and abundant genetic diversity, and their genetic relationship showed certain regional ecotope law. The first two principal components should be paid more attention to select in variety breeding in southern China.