美洲黑杨杂交子代苗期性状遗传变异及选择

  目的  分析美洲黑杨Populus deltoides杂种苗期生长性状和叶片性状的遗传变异及遗传相关性，为杨树新品种选育提供材料。  方法  以美洲黑杨不同品种为亲本进行杂交试验，测定了9个杂交组合子代苗期生长性状和叶片性状，并通过方差分析、遗传参数估算、遗传相关分析及通径分析等，了解美洲黑杨杂种生长性状和叶片性状的遗传变异规律及性状间遗传互作，并依此开展美洲黑杨优良杂交组合的联合选择。  结果  杂交组合间3个生长性状与5个叶片性状存在显著(P＜0.05)或极显著(P＜0.01)差异。苗高、地径、材积与叶长、叶宽、叶柄长、叶周长、叶面积的家系遗传力均达0.8以上，受强度遗传控制，遗传变异系数为8.6%(叶长)~31.13%(材积)，有利于优良杂交组合的选择。相关分析表明:叶长、叶宽、叶柄长、叶周长、叶面积与苗高、地径、材积间均达极显著正遗传相关(P＜0.01)。相关遗传进度分析表明:除叶形指数、侧脉夹角和叶宽基距外，其他叶片性状对3个生长性状的遗传相关进度和间接选择效率较高。通径分析表明:苗高和地径对材积的直接遗传控制作用较大，叶长、叶宽、叶柄长、叶面积和叶周长通过苗高和地径对材积产生较大的间接遗传控制作用。利用综合指数选择法开展美洲黑杨9个杂交组合的生长与叶片性状联合选择，选出3个速生优质的杂交组合(B106×NL15、S3239×NL15、NL447×SY2)，材积遗传增益达26.90%。  结论  美洲黑杨杂交组合子代1年生苗的3个生长性状和5个叶片性状均存在丰富变异，遗传互作显著；苗高和地径对材积的直接作用最大，5个叶片性状对材积也产生较大的间接控制效应。综合指数选择法能有效地选出速生优质杂交组合，材积遗传增益较高，杨树遗传改良效果较好。表8参18

Genetic variation and selection of seedling traits in hybrid progeny of Populus deltoides

  Objective  The objective of this study is to analyze the genetic variation and correlation of seedling growth and leaf traits of Populus deltoides hybrid, so as to provide materials for breeding new poplar varieties.  Method  The hybrid experiment was carried out with different varieties of P. deltoides as parents, and the seedling growth and leaf traits of nine hybrid combinations were measured. The genetic variation and genetic interaction of growth traits and leaf traits were studied through analysis of variance, estimation of genetic parameters, genetic correlation analysis and path analysis. On this basis, the joint selection of fine hybrid combinations of P. deltoides was carried out.  Result   There were significant (P＜ 0.05) or extremely significant (P＜ 0.01) differences in seedling height, ground diameter, volume and leaf traits among hybrid combinations. The family heritability of the three growth traits (seedling height, ground diameter, volume) and the five leaf traits (leaf length, leaf width, petiole length, leaf perimeter and leaf area) were all above 0.8, which were controlled by intensity heredity. The genetic variation coefficient ranged from 8.6% (leaf length) to 31.13% (volume), which was beneficial to the selection of superior hybrid combinations. The correlation analysis showed that there was a extremely significant positive genetic correlation (P＜0.01) between leaf traits (leaf length, leaf width, petiole length, leaf perimeter, leaf area) and seedling height, ground diameter and volume. The analysis of correlation genetic progress indicated that, except for leaf shape index, lateral vein angle and leaf width base distance, the genetic correlation progress and indirect selection efficiency of other leaf traits to the three growth traits were higher. The path analysis showed that seedling height and ground diameter had greater direct genetic control on volume, while leaf length, leaf width, petiole length, leaf area and leaf perimeter had greater indirect genetic control on volume through seedling height and ground diameter. Combined selection of growth and leaf traits of nine hybrid combinations of P. deltoides was carried out by comprehensive index selection method, and three fast-growing and high-quality hybrid combinations (B106×NL15, S3239×NL15, NL447×SY2) were selected. The genetic gain of volume reached 26.90%.  Conclusion  The three growth traits and five leaf traits of 1-year-old seedlings of P. deltoides hybrid combinations show rich genetic variations and significant genetic interaction. Seedling height and ground diameter have the greatest direct effect on volume, and the five leaf traits also have a large indirect control effect on volume. The comprehensive index selection method can effectively screen fast-growing and high-quality cross combinations. The genetic gain of volume is higher, and the genetic improvement effect of poplar is better. Ch, 8 tab. 18 ref.]