Genetic Potential Of Nine Synthetic Maize Populations

In the study the material were 9 synthetic maize populations and 54 combinations derived form crosses to 6 testers based on an incomplete diallel disign.These materials were provided by SiChuan Agricultural University Corn Research Institute and SiChuan Academy of Agricultural sciences.The GCA of synthetic maize populations and the SCA of 54 combinations of major agronomic traits were evaluated in an incomplete diallel design;the genetic variation of the 60 individuals was evaluated by SSR primers.The main results were summarized as follows:1.Field results of the 9 synthetic maize populations showed that variances were significant in all the observed traits except ear length,barren ear tips length and ear diameter.2.Comparisons of main means showed that plant height and ear height were higher in 06P7;Cob weight and cob diameter were higher in 06P3;Percentage of kernel to cob and 100-kenel weight were higher in 06P5;Rows/ear,ear weight and yield per plant were higher in 06P4;Kernel per row was higher in GP-5.The multiple comparisons showed that most maize populations had exact genetic differences in every trait.3.From the comparisons of main agronomic traits CV,great genetic variation was detected within the 9 synthetic maize populations while the yield traits were greater than plant traits.From big to small,the order of yield traits was yield per plant,ear weight,cob weight,kernel/row,rows/ear,Cob diameter,100-kenel weight and percentage of kernel to cob.4.Analysis of combing ability in traits witch variances were significant showed that the GCA of most traits observed were significant among 9 synthetic populations.The SCA of many agronomic characters were detected that it was significant between combinations. The results of GCA showed that the plant traits of 06P1,06P4 and GP-5 were higher,and the yield traits of 06P7 and 06P8 were better.5.Taking the measure of the yield per plant of combinations which was higher than the control with 8%,the analysis showed that there were 37 combinations,in which 16 combinations were higher than the control with 20%,18 combinations were higher than the control between 10%～20%.Among the 37 combinations,there were 6 combinations coming from 06P8,5 combinations coming from 06P3,06P4,06P5 and 06P7,4 combinations coming from 06P1 and GP-5,2 combinations coming from 06P2,only 1 combination coming from 06P6.Furher more,it showed that 06P7 and 06P8 were better than other synthetic maze populations.6.At the same time,we analyzed the 9 populations with their SSR markers.The genetic diversities of all the 9 maize populations were detected by 30 SSR primers,which were distributed on the 10 maize chromosomes.In these populations,totally 189 alleles was detected,And there were 135 to 165 polymorphic loci in each populations.The population of 06P5,06P1,06P6 and GP-5 with a bigger average number of polymorphic loci.The range of genotype number was 193 to 300,and GP-5,06P4,06P1 and 06P5 with a higher value.The range of populations' own similarity coefficients was 0.6328 to 0.6638, the 06P1,06P4,06P5,06P6 and GP-5 with a little smaller value.The range of average number of effective number of alleles was 2.4325 to 2.8377,GP-5,06P4,06P1 and 06P5 with a higher value.;observed heterozygosity was 0.4889 to 0.6111,06P5,06P1,06P6 and GP-5 with higher value.The comprehensive analysis of genetic diversity parameters showed that all synthetic maize populations had a broad genetic diversity.The 06P1,06P4, 06P5 and GP-5 had a more broad gentic diversity.Chart 13 showed that the populations' own genetic diversity was more extensive than that between populations.7.SCA in plant yield in the 36 hybrid combinations with model tester were used as a basis for the classification of heterotic groups.All synthesized maize populations were classified into four heterotic groups.The four groups were 06P1,06P4,06P7 and 48-2, 06P3,06P8 and R08,06P2,06P6 and Ye 478,06P5 and 48-2 or Ye478,GP-5 and Huang-zao 4.The last group was different with the genetic background,the reason need further research.When the genetic similarity coefficients at the level of 0.602,the populations can be classified into four groups based on SSR marker.The four groups were 06P1 and 06P2,06P3,06P8 and GP-5,06P4 and 06P7,06P5 and 06P6.The interaction of genotype and environment may cause the different analysis of two type of clumster.It concluded that 06P7 and 06P8 seemed to have great potential for improvement; GP-5 of the control group,although with the higher mean of major yield traits and larger variation degree,the output of the main traits and the performance of the GCA were poor. It needed high import genetic recombination before further utilization improving;06P2 and 06P6,with the main yield traits poor performance of GCA,were not the potential for breeding.Comparison with the results of small populations(06P1-06P8) and large populations(GP-5) showed that a certain number of parents on the basis of the synthesis of high and low levels of populations involved in its synthesis of the pro-restructuring,as well as its pros and cons of how much more closely related.