Evaluation Of Breeding Potential Of Domestic And Exotic Maize Populations To Improve Hybrids XianYu335and JiDan27

The narrow in genetic basis has limited the sustainable development of maize hybrids andproduction.New excellent germplasm and hybrids would be created through using maizepopulations that have rich genetic basis to improve the defects of parental lines of current hybrids,which has become a significant method to breed new varieties and broaden the genetic basis ofmaize germplasm in China. This study was aimed at improving the resistance to head smut,adaptation to high density, higher plant and ear height, lower lodging-resistance capability ofXianyu335， and axis rough, slow dehydration rate of seed, flat leaf, nonresistant to density, along bald tip of Jidan27.The parental lines of Xianyu335-PH4CV, PH6WC, and Jidan27-Si-144，Si-287was taken as the female parent while twelve excellent domestic and exotic maizepopulationas was taken as male parent to produce combinations through a incomplete diallelcross. The artificial inoculation of smut and leaf spot and non inoculation was used to evaluatethe resistance of the parents and the hybrids. The potential of the populations in improvingXianyu335and Jidan27was evaluated through the estimate of the parameters of significantcharacteristic. The results were summarized as follows:（1）Evaluation of agronomic traits showed that in terms of plant height and ear height, BS19,BS20, BS22, and Zhongzong7were suitalbe; The LOV of Zhongzong7and Zhongzong6waslarger; The bald tip of LANCASTER, BS19, BS20, BS21, BS22, POB43, STAYGREEN-Y,Zhongzong6, and Zhongzong7were shorter; the axises of POB28,BS19,BS20,BS21,BS22,STAYGREEN-Y,POB43and BP10were thinner; the yield of Zhongzong7, BP10,BS21washigher;BS20,BS21,BS22,SUWAN1,STAYGREEN-Y,LANCASTER,Zhongzong6,and Zhongzong7had moderate resistance to corn smut, while other groups were highly susceptible to smut.Theresults showed that the populations had beneficial genes to improve the disadvantage ofXianyu335and Jidan27.（2）According to Dudley’s theory of gene transfer, Zhong zong7was the best favorablegene donor, which could improve the resistance to smut, adaptation to high density, higher plantand ear height of Xianyu335simultaneously. The plant height of Xianyu335would be reduced,and the resistance to high density and smut would be enhanced if the male parent of Xian yu335-PH4CV was improved; the ear height of Xianyu335would be reduced if the female parentof Xianyu335-PH6WC was improved. Continuous selfing of hybrids was the suitable method toreduce the plant and ear height. Taking PH4CV as the recurrent parent,continuous selfing afterone or two generations of backcross was the preferable improvement method to enhance LOV andthe resistant to smut.（3）According to Dudley’s theory of gene transfer, Zhongzong6and Zhong zong7was thebest favorable gene donor to improve the LOV and bald tip of Jidan27, BS22and BS43was thebest favorable gene donor to improve the corncob of Jidan27. The comprehensive improvement ofJidan27would be achieved only if two groups were used simultaneously. To improve the LOV, themale parent of Jidan27(Si-144) should be improved using Zhongzong6or Zhongzong7,and the bestimprovement method was the continuous selfing after one or two generations of backcross takingSi-144as the recurrent parent.To improve the bald tip, In meantime of the female parent ofJidan27(Si-287) should be improved using Zhong zong6or Zhong zong7, and the best way was thecontinuous selfing of hybrids to breed inbred lines with reduced bald tip. To reduce the corncobdiameter of Jidan27, the female parent of Jidan27(Si-287) should be improved using BS22orPOB43, and the best improvement method was continuous selfing after one or two generations ofbackcross taking Si-287as the recurrent parent.