基于果实表型的核桃种质资源遗传多样性分析

Analysis of Genetic Diversity of Walnut Germplasm Resources Based on Fruit Phenotype

研究核桃种质资源果实表型多样性和变异特点,为核桃优良种质的构建、新品种选育提供数据基础和理论依据,从而促进核桃种质资源的合理开发利用。以99份来自石门、新疆、辽宁产区的资源为试材,测评了果实的13个质量性状和11个数量性状,测定并分析性状的分布频率、变异系数、Shannon-weaver遗传多样性指数及表型分化系数,分析24个性状指标间的相关性,并进行聚类分析。13个质量性状的变异系数变幅为16.57%~54.46%,其中甜味、内褶壁质地、取仁路数、种壳麻坑多少、取仁难易、涩味、种壳光滑度等7个性状的变异系数较大;质量性状的遗传多样性指数变幅为0.49~1.51,其中取仁难易、取仁路数、种壳光滑度、种皮颜色、涩味等5个性状的遗传多样性指数较大。11个数量性状的变异系数变幅为8.38%~26.91%,其中种仁质量及种壳厚度2个性状的变异系数较大,其遗传多样性指数变幅为1.89~2.27,其中坚果横径、坚果棱径、种壳厚度的遗传多样性指数较大。除坚果质量及坚果横径在群体间差异不显著外,其余性状在群体间及群体内均达到极显著差异水平;群体间及群体内方差分量百分比均值分别为15.66%,58.13%。取仁难易与种壳厚度(r=-0.618)、出仁率(r=0.573)、取仁路数(r=0.790)、内褶壁退化程度(r=0.733)及质地(r=0.659)极显著相关;通过系统聚类,依据表型差异可将试材分为3大类群,且类群间特点显著。核桃果实的表型性状变异丰富,且在选育品种过程中应重点关注取仁难易、取仁路数、种壳光滑度、涩味、种壳厚度、内褶壁退化程度及质地等相关性状。变异主要来源于群体内(果形指数除外),因此,群体内优良品种的选择更应受到重视。

The study on the diversity and variation of fruit phenotypic characters of walnut germplasm resources can provide valuable based data and theory foundation for construction of walnut germplasm resources and variety breeding,and promote the efficient utilization of walnut germplasm resources.The study was conducted in order to evaluate 13 qualitative characters and 11 quantitative characters on 99 walnut germplasm resources,which were designed with hierarchical classification and then were done with analysis of variations and systematic cluster analysis.The results showed that the coefficient of variation of the 13 qualitative characters ranged from 16.57% to 54.46%,especially,coefficient of variation concerning 7 out of 13 characters including sweet,texture of crisp,number of kernel,number of pockmark,degree of difficulty taking kernel,astringency and smooth of shell.The Shannon-weaver index of the 13 qualitative characters ranged from 0.49 to 1.51,especially,Shannon-weaver index concerning 5 out of 13 characters including degree of difficulty taking kernel,number of kernel,smooth of shell,color of shell and astringency.The coefficient of variation of the 11 quantitative characters ranged from 8.38% to 26.91%,especially,coefficient of variation concerning 2 out of 11 characters including weight of kernel and thickness of shell.The Shannon-weaver index of the 11 quantitative characters ranged from 1.89 to 2.27,especially,Shannon-weaver index concerning 3 out of 11 characters including equatorial diameter of nut(2.27),side diameter of nut(2.27),thickness of shell(2.27).There were significant differences among and within populations(except nut weight and equatorial diameter of fruit),and phenotypic differentiation coefficient among and within populations were 15.66% and 58.13% respectively.The degree of difficulty taking kernel had extremely significant correlation with thickness of shell(r=-0.618),kernel rate(r=0.573),number of kernel(r=0.790),degeneracy of crisp(r=0.733),texture of crisp(r=0.659).The systematic cluster analysis showed that 99 test materials could be divided into 3 categories based on the variation of phenotypic characters and in which there were differences.There were abundant genetic diversity based on the phenotypic characters of fruit of walnut,and these characters were worth mentioning such as degree of difficulty taking kernel,number of kernel,smooth of shell,astringency,thickness of shell,degeneracy and texture of crisp in the variety breeding.The variation within populations was more abundant(except the fruit shape index),and we can pay attention to the genetic improvement within populations.