Combining Ability Evaluation And Genetic Analysis For Grain Yield Of Inbred Lines And Hybrids From Shaan A Group And Shaan B Group

Elite inbred lines are the key to cultivating elite hybrids,and the key to the quality of inbred lines lies in the evaluation of combining ability.In order to evaluate the effect of combining ability,and mining excellent genetic variants loci,56 inbred lines of maize were selected from Shaan A group and Shaan B group in this study.A total of192 hybrid combinations were assembled by NC-Ⅱgenetic design based on 4（B）×19（A）+4（A）×29（B）.By the evaluation of the yield combining ability of maize inbred lines in 5 environments,genome-wide association study based on the yield of F₁population and its special combining ability（SCA）was carried out.The study aims to screen out elite inbred lines and elite hybrid combinations,and mining genes significantly related to hybrid traits.The main results are as follows:1.The yield range of variation of hybrid population was 9.09%～15.62%in 5environments,and environmental effects accounted for 63.68%of the total variation,followed by genotype-environment interaction effects and genotype effects,accounting for 22.40%and 7.49%,respectively.It indicates that environmental factor is the most important factors affecting the yield of hybrid population.In high yield and stable yield analysis,the yield of hybrid combinations 2019KA-23-2×KB179-2,2019KA-89-1×KB208 is good and has certain application potential.2.The evaluation of the combining ability showed that the tester KA105 perform ed the best in the Shaan A group,and the testers KB179-2 and KB208 performed well in the Shaan B group in the evaluation of general combining ability;the tested lines 2019KA-23-2,2019KA-89-1,2019KB-76-3 have high general combining ability and it s stability is good.In the evaluation of special combining ability,KA115×2019KB-43-4,2019KA-89-4×KB208,2017KA-52-2×2019KB-76-4,2019KA-23-1×KB210,KA327×2019KB49-1,KA115×2019KB-16 are materials with high special combining ability and good stability.3.The results of genome-wide association study（GWAS）showed that,a total of27 SNPs significantly correlated with yield and 13 SNPs significantly correlated with yield SCA were detected in additive,dominant and recessive models.Among them,2of the SNPs were co-located with yield and yield SCA.By screening,34 PVE≥1%association sites were obtained.Taking the gene closest to the physical location of the significant site as the candidate gene,29 genes with functional annotations were predicted to nominate.Further analysis showed that the enrichment of favorable alleles was conducive to the increase of hybrid yield.In sum,this study used the multi-environment combined trial in breeding to evaluate inbred lines and hybrids,and combined with genome-wide association study technology to identify the associated sites of yield and special combining ability.So that the basic research and breeding practice can be effectively integrated,and at the same time,it provides a way for future hybrid breeding.