Genetic Improvement Of Backbone Line Y59 Of Maize Non-reid Group And Its Improved Lines

The expansion and improvement of maize germplasms resources is an important way to solve the problems of narrow resources,serious homogeneity and close genetic relationship among varieties in China.Introduction and improvement of introduced germplasms resources is an effective way to expand maize germplasm resources.Introduced non-Reid group backbone lines PH4 CV and PH5 AD are the important germplasms that suitable for the main production areas of spring maize in north China.The non-Reid group backbone line Y59 with high combining ability,resistance to Northern corn leaf blight were cultivated by the double haploid breed technique(DH)based on the hybrid of PH4 CV and PH5 AD.However,during test,shortcomings such as its late growth and development period were revealed.Therefore,a new improved line was developed by using early maturing materials.In this study,the genetic characteristics of the improved lines were studied in order to provide materials and techniques for breeding middle stem hybrids.5 Reid inbred lines J1072,PH6 WC,J2102,J1049 and J1029 were used as female parents.According to the NCII design,25(5×5)crosses were prepared.The significant difference analysis,heterosis,combining ability and genetic parameters of yield per plant,yield factors,plant height,bald tip length and other main traits of 25 hybrids were studied.The results are as follows:1.The analysis of significance of difference in main characters showed that there were significant and very significant differences in main characters of the hybrids,among which J1029×J5916 had outstanding performance in agronomic traits such as yield per plant,100-kernel weight,ear weight,ear length,kernel per row.2.The analysis of heterosis showed that the variation range of heterosis in single plant yield was 5.25%-99.45%,the average heterosis was 70.33%,and the coefficient of variation was7.44%.The hybrid J1029×J5916 had the highest heterosis value(99.45%).The order of median parental advantage of other agronomic traits was ear weight,ear height,yield per plant,cob weight,plant height,kernel per row,ear wide,stem diameter,100-kernel weight,ear length,baid length.3.The analysis of combining ability showed that J5916 had the highest effect value of general combining ability(GCA)per plant yield and 100-kernel weight,which was higher than PH5 AD,Y59 and other improved lines,and had the best performance and the ability to increase yield.Yield per plant and 100-kernel weight,special combining ability,hybrid combination j1029×J5916 performed best at 19.11 and 21.92 respectively,respectively,indicating that the improved inbred line J5916 was easy to produce high yield hybrid combination.4.The genetic parameter analysis showed that the generalized heritability of the 12 characters was above 50%,the 100-kernel weight was the largest(93.51%),and the number of rows per ear was the lowest(47.12%).The narrow heritability of the 12 characters was above50% and the minimum cob diameter was 50.23%.5.Genetic gain analysis showed that many agronomic traits in both basic and improved lines had better genetic improvement effects.The improved line M3(J5916)had better improvement effect in increasing yield per plant and100-grain weight.Therefore,continuous improvement of non-Reid group core germplasm can obtain excellent inbred lines,and provide theoretical support and material basis for maize genetic improvement and excellent inbred line breeding.