Agronomic Traits Evaluation And Genetic Diversity Of Pear Germplasm Resources

Pear is a special economic fruit tree in China and one of the most popular fruits in the world.The fruit of the pear is rich and comprehensive,the flesh is crisp and juicy,the sweet and sour taste is good,the flavor is excellent,and the fresh pear fruit is rich in various nutrients,so it is known as the “fruit of the hundred fruits”.However,the competitiveness of Chinese pear in the international market is still low,mainly manifested in poor fruit appearance,low quality fruit rate,low soluble solid content,uneven quality,lack of excellent germplasm and so on.Therefore,in this study,34 pear germplasm resources stored in the pear germplasm resource nursery of the University of Tarim were used as test materials to discuss the genetic diversity of pear germplasm resources,and finally comprehensively evaluate the quality of pear fruit with the grey correlation degree.The main results are as follows:(1)Pear germplasm resources have rich genetic diversity of agronomic traits.The genetic diversity index(H’)of leaf,flower and fruit traits is distributed between 3.38 and 3.52,and the variation coefficient of leaf quantitative traits is between 10.02 and 20.88%.The variation coefficient of inflorescence setting rate was52.25%.The variation coefficient of fruit quality ranged from 10.68 to 38.57%.The variation coefficient of mineral element content was 55.93% and 9.79% respectively.At the same time,the quality characters of leaves,flowers and fruits were classified.(2)According to the correlation analysis of the leaf traits of pear germplasm resources,there were three pairs of traits showing extremely significant positive correlation.There was an extremely significant negative correlation between 1 pair of characters.The correlation analysis between the inner quality of pear germplasm resources and the content of mineral elements showed that there were 11 pairs of positive correlation and 3 pairs of negative correlation.(3)When the cumulative contribution rate reached 85.02%,10 principal component factors were obtained by principal component analysis.The quantitative characters of leaves,flowers and fruits were simplified from 30 to 15 and applied to cluster analysis.(4)The data of different dimensions were standardized and the variable class average clustering method was used for clustering analysis.34 pear germplasm resources were divided into 4 categories at the Euclidean distance of about 12.47,and the relationship of germplasm in each group was further discussed.(5)Through the comprehensive evaluation of the grey relational degree of fruit quality,9 excellent germplasm resources were preliminarily screened out: Nansui,AiGanshui,Mansoo,Xuefeng,Manfeng,Lubaoshi,Suisho,Luyun,Cuiyu,Shinseiki.