Study on the strategies of integrating qualitative and quantitative traits for constructing core collection
整合质量数量性状构建作物核心种质的策略研究

Genetic differences between accessions can be reflected by qualitative and quantitative traits at diverse levels. Currently, qualitative traits and quantitative traits are independently utilized in measuring genetic similarity between individuals. A strategy of integrating qualitative traits and quantitative traits was proposed for establishing a core collection of germplasm; adjusted Euclidean distance was found effective in detecting genetic differences between accessions, which is also flexible in dealing with missing data. A case study was conducted on 10 qualitative and 15 quantitative traits of 2262 rice accessions collected and investigated by the Rice Ecology Research Lab of the Chinese Academy of Agricultural Sciences, the South China Agricultural College and the Guangdong Academy of Agricultural Sciences; adjusted Euclidean distance and the Unweighted Pair Group Method with Arithmetic mean (UPGMA) were used in classification of population; 8 nested core subsets were sampled by stepwise clustering with preferred sampling strategy, for evaluating the proposed method. The results showed that subsets based on integrated strategy harbored widen genetic diversity of qualitative and quantitative traits; qualitative traits are not effective enough in measuring genetic differences between accessions; constructing of core collection should be based on quantitative traits associated with integration of qualitative information, if possible.