Abstract:

【Objective】 The genetic diversity of 15 quantitative traits from 300 Malus sieversii accessions was used to study the method of constructing Malus sieversii core collection. 【Method】 A total of 24 Malus sieversii core collections were constructed at 30% sampling proportion by two genetic distances, including Euclidean distance and Mahalanobis distance, combined with four cluster methods including UPGMA, Ward’s method, Complete linkage and Single linkage, and with three sampling methods including random sampling, deviation sampling and preferred sampling, respectively, using stepwise clustering. Using the best constructing method, the optimum sampling proportion was filtrated under seven different sampling proportions (10%, 15%, 20%, 25%, 30%, 35%, and 40%). 【Result】 In constructing Malus sieversii core collection, Euclidean distance was much better than Mahalanobis distance. Comparing the four cluster methods, the single linkage was better than UPGMA, Ward’s method and Complete linkage for constructing core collection. The preferred sampling was more suitable than deviation sampling, although the deviation sampling could also significantly increase VD%, CR% and VR%. Twenty percent was the optimum sampling proportion.【Conclusion】 At 20% sampling proportion, using stepwise clustering, Mahalanobis distance and Single linkage method combined with preferred sampling can construct the most reprehensive core collection and is the most suitable method for constructing Malus sieversii core collection.

Key words: Malus sieversii, core collection, genetic distance, cluster method, sampling method