The Study On Genetic Diversity And Combining Ability Of 53 Maize Inbred Lines From Recycling Selection

In view of the current narrow genetic heritage of maize breeding in China,the study relied on the national corn technology system,and adopted the domestic excellent inbred lines of Tie7922 and Ji13S228 as recipients based on circular breeding strategies,and used foreign excellent inbred lines as donors.Group A and B groups were formed,In addition,53 inbred lines were screened by a high density identification technique such as 15000 plants/hm2.Molecular marker technology and NCII genetic mating design.PHB1 M and PH6 WC were used as test species and tested with 53 cycles of materials.Genetic diversity,combining ability and heterosis analysis were conducted in order to evaluate their combining ability and breeding potential.The main results are as follows:(1)Using SSR markers analysis,the genetic diversity of the improved line of Ji 13S228 was higher than that of the Tie 7922 improved line.A total of 83 alleles variants were detected in the Tie7922 modified line,with an average of 2.13.and the PIC averaged 0.26,and the genetic diversity averaged 0.31.A total of 140 alleles variants were detected in the Ji13S228 modified line,with an average of 3.51.and the PIC averaged 0.37,and the genetic diversity averaged 0.42.(2)The genetic distance between the Ji13S228 improved line and the inbred line Ji13S228 was the smallest(0.09).4.The genetic distance between the Tie7922 improved line and the inbred line Tie7922 was also closer(0.16).Reveal the genetic background of the improved lines to improve the receptors.(3)According to the UMGMA method,principal component analysis and model clustering,62 inbred lines were divided into two major groups:SS group(Tie7922andTie7922 improved line?B73?PH6WC andYe478),NSSgroup(Ji13S228 and Ji13S228 improved line?MO17?Dan340?Huang zaosi and PHB1M).(4)53 parts of this cycle-based material selected from the combining ability analyzed,and 8 parts of fine screening material,Three groups of A groups(S1821,S1814,S1813),5 groups of B groups(S1861,S1870,S1828,S1838,S1841).The next step is to focus on these new materials.(5)After two trials a year screened two new combinations of high and stable yields(S1821/PHB1 M and S1814/PHB1M).The average yield at the two experimental sites in Gongzhuling and Tongliao increased by 10.59% and 7.93%,respectively,compared with the control Xianyu 696.The 11 combinations only performed better in Gongzhuling,and 3 of them produced more than the control Xianyu 335.The next step for these combinations need to be multi-years-point identification;.(6)The analysis of combining ability and heterosis showed that PHB1 M is an greater utility value of inbred line.The heterosis of the cross combinations of the 53 inbred lines and the tester PHB1 M was higher than that of the tester PH6 WC,and the heterosis of the cross combination of the Tie7922 improved line and the test species PHB1 M was higher than that of the Ji 13S228 improved line.Molecular genetic distance and field trials confirmed.The genetic distance between the tester PHB1 M and the Tie7922 improved line was(0.93)far more than from the Ji13S228 improved line(0.71).In the 106 combinations,two new combinations with high yields and stable yields were selected from the cross combinations of the Tie7922 improved line and the tester PHB1 M.6.The heterosis pattern of Tie7922 improved line × PHB1 M has great value in use.