Breeding Potential Of Elite American NSS Inbred Lines × Huangzao 4 To Improve A Chinese Maize Hybrid Zhengdan 958

The local elite maize(Zea mays L.)hybrid Zhengdan 958(Zheng 58×Chang 7-2)has been applied for 15 years.It has been hampered by the lack of the superior alleles for improving grain yield and lowering the water content of the kernels(by 6%)that were at the stage of harvest that did not suit mechanized harvesting.The purpose of the study is to use the medium American inbred linesxearly Chinese inbred line Huangzao 4 as donors to evaluate its breeding potential to improve Zhengdan 958.Thirteen donors(American inbred lines x Huangzao 4)were evaluated to identify alleles for improving a widely cultivated hybrid Zhengdan 958.Sixty-eight genotypes,comprising 13 donors,two inbred lines(Zheng 58 and Chang 7-2),a single-cross hybrid(Zheng 58 x Chang 7-2),and 52 donor x inbred crosses between 13 donors and 4 test lines(Zheng 58,Chang 7-2,Ye 478 and Huangzao 4)were evaluated in 2014 at four locations(Anyang in Henan Province,Wuhan and 2 locations of Xiangyang in Hubei Province)for grain yield,kenels’ moisture,plant height,ear height,ear length,bald tip length,ear width,cob width,number of kernel rows,number of kernels per row,1000-kernel weight and kernels rate.Six genetic parameters(1 piμ’,PTC,UBND,NI,SD and SB)were used to determine the breeding potential of 13 donors to improve the target hybrid.The results were summarized as follows:(1)The promising germplasms,donor 10 and 13 had the potential for further improving grain yield of the target hybrid Zhengdan 958,which could be used to improve the parental lines Chang 7-2 by taking Chang 7-2 as the recurrent parent,continuous selfing after one or two generations of backcross.(2)Donor 12 had the potential for simultaneously lowering the water content of the target kernels that were at the stage of harvest(5%～6%),which could be used to improve the parental lines Zheng 58 by taking Zheng 58 as the recurrent parent.(3)Donor 11 had the potential for further lowering the plant height of the target hybrid.Donor 1 and 7 had the potential for further lowering the ear height of the target hybrid.They could be used to improve the parental lines Zheng 58 by taking Zheng 58 as the recurrent parent,continuous selfing after one or two generations of backcross.(4)Ear length,barren tip,rows per ear,kernels per row,ear diameter,cob diameter,kernel rate and 1000-kernel weight are significantly relative(0.05 or 0.01)to grain yield.The comprehensive effect about these traits to grain yield are ranked as follow,ear length>kernel rate>cob diameter>kernels per row.The effect of cob diameter is negative,while others’ are positive.