Breeding Potential Analysis Of Different Types Of Populations

The preparation of test materials were ten groups (three local varieties groups, three tropical and subtropical groups and four Synthetic groups)and six kinds of Standard test species which were made combination by designed by NC II. Use the method that combines field trials and SSR molecular markers to test and analysis for the main agronomic and economic characters and combining ability and genetic diversity in the tested groups. And the test's results are obtained as the follows:1. The variance analysis of main agronomic and economic characters showed that, except ear length, bare tip length, grain depth and test weight were not significant, the other 10 characters including spinning period, loose powder period, plant height, ear height, ear line, ear diameter, grain line, spike weight, yield per plant and 100-kemel weight were extremely significant.2. Multiple comparisons results showed that all traits here were have great differences. A gronomic and economic traits of the Synthetic groups were performance well. The POOL26 in tropical and subtropical species groups and DP56 in local varieties groups were performance better than the others.3. The analysis of the coefficient of variation in groups' main characters showed that diffident main characters in one group's coefficient of variation represent great differences. The same characters in different groups' coefficient of variation represent great differences either. The differences explaned there had a rich genetic variation, and there were great genetic differences between the groups. Among them, the largest variation is the ear of 05WG1030, is the smallest variation is rows of 05WG1030 in all groups.4. The frequency of occurrence comparison table of the 3 groups' excellent individual showed that local varieties groups were low DP56, DP8 and DP17, tropical and subtropical groups were low POOL26, La Posta and P28, synthetic groups were low P3MSC4, 05WG1030, P4HSC3 and P5HSC3. Depended on the different types of groups from the mean of excellent individual frequency , the synthetic groups was significantly higher than the other two groups, furthermore local varieties groups were slightly higher than tropical and subtropical groups.5.GCA and clusters in the tested groups showed that P4HSC3, P3MSC4 and 05WG1030 in synthetic groups performanced better in agronomic and economic traits GCA, they have greater potential for use. SCA analysis showed that, the hybrids which had the highest SCA ,their parents not necessarily had highest GCA. So during the corn breeding, GCA and SCA both performanced important roles in the high-yielding hybrid combinations. It is necessary to pay attention to chose of the SCA during choice of GCA.6. Depended on the analysis of SCA effects of the value of yield per plant as the genetic distance cluster the 10 groups can be respectively classified in five standard test species which represented by five national and abroad heterosis groups. Groups P5HSC3, DP56 and P4HSC3 were classified into Reid group; groups DP8, P28, and La Posta were classified tropical group ; groups DP17 and POOL26 were classified into Huang Zaosi group, groups P3MSC4 and 05WG1030 were classified into Lancaster group;So far, in the tested groups, we found no suitable groups could be classified into Dan598 group.7.SSR genetic diversity analysis showed that the use of 27 pairs of primers for amplification of 300 samples, there were a total of 184 alleles had been detected, each SSR marker could sign 4 to 12 alleles, the average is 6.81; analysis of gene heterozygosity, genotypes and genetic distance within individual in groups showed that gene heterozygosity had greater mutation rate in each group,but smaller heterozygosity average among all groups. the size of gene heterozygosity of Three types of groups were low synthetic groups, local varieties groups and tropical and subtropical groups. The highest gene heterozygosity is group DP8, the group DP17 and La Posta were lower, the others were not significant. Group genotype analysis results show that the largest was group P28, the least was group 05WG1030.The number of genotype were larger in all groups , further improved that there were rich genetic variation. However,There a number of genotype differences in different types of groups,so as the different groups among same type. The genetic distance between each individual among groups ranged from 0.62-0.93, the shortest is group La Posta, the longest is group P28. And it's average showed that the tropical and subtropical groups were longer than the local varieties groups and synthetic groups,it improved that tropical and subtropical groups had the larger genetic variation, and the synthetic groups were similar with local varietiesgroups.