用于杂交种改良的群体的遗传评价

Evaluate the Population Useful for Hybrid Improvement

用于杂交种改良的供体亲本的选择一直是人为的,没有完善的数量遗传理论指导。本文采用数量性状基因分组的概念,依据加性——显性模型,给出了评价群体供体亲本的9个遗传参数,可以有效地指导杂交种改良:①EP_4值较大的群体可作为供体亲本;②若 Cp_2+Dq_s>Cq_2+DP_s,则应用群体 P 改良 I_1,反之,则应用 P 改良 I_2;③可以运用遗传参数进行杂交种改良的育种决策;④显性度大小对于育种决策有重要影响。

After distinguishing the three parents I_1,I_2,(the two inbreds of an elite single hybrid)and donor parents(P,population)by dividing the quantitative genes among 6 classes of loci,the genotypic value of parents and their crosses were infered according to additivc-dominance model.Then,methods to estimate variance of testcross generations,degree of dominance(a),effect of single allele(d,h),number of genes on D.C classes of loci,and gene mean frequency on D.C classes of loci in the population(p_2,P_3),were devel- oped.Other genetic parameters useful for evaluating the popalation(Bq_2,Ep_4)ware given out.A few ques- tions related to the hybrid improvenent are discussed:①Appropriate population should be selected to improve the elite single hybrids.②Population should be used to improve I_1 inbred when(C_(p_2)+D_(q_3))>(C_(q_2)+D_(p_3)),oth- erwise population should be used to improve I_2 inbred.③How to improve inbreds have been considered.④de- gree of dominance influences greatly the breeding strategy.