| In present study,21 inbred lines derived from 7 synthesized maize populations were used as males to make a total of 126 NCⅡtestcrosses with 6 often used inbred lines in southwest China. The combing ability, heterosis and genetic indexes of main traits of 21 inbred lines were estimated. The heterosis groups and heterosis pattern of 31 inbred lines, including the 21 inbred lines derived from 7 synthesized maize populations,6 testers and 4 temperate inbred lines (S37, Huangzaosi, Dan598 and Ye478), were studied with SSR markers. The main results were summarized as follows:1. Variance analysis showed that plant height, ear height, ear length, sterile length, kernel length, rows per ear, kernels per ear, grain yield, shelling per cengtage,100-kernel weight and unit weight were observed significant level, indicating the 11 agronomic traits of the hybrids existed true genetic differences.2. The combing ability analyses according to NCⅡdesign indicated that the GCA and SCA of all traits were significant at 0.05 or 0.01 level except for the SCA for grain yield of testers and the SCA for the sterile length. KS123 and KS73 better breeding potential because they performanced higher GCA in grain yield and yield component traits; followed by KS116, KS191, KS260, KS71, KS144 and KS120, their grain yield of GCA wre high and most yield component traits of the GCA were positive, may have some prospects; the remaining selections performance poor prospects, recommending as a germplasm preservation.3.126 combined SCA effects value of grain yield ranged from-46.63-37.31. Strong heterotic crosses with high SCA were SCML103×KS73, RO8×KS103, RO8×KS163,975-12×KS152 and RP125×KS120. Combined with previous analysis of GCA showed that, most of the combination of high SCA, their parents or one of parents are high GCA, low SCA combination, their parents are all low GCA, but there are special combinations, which high GCA of parents, showed low SCA. Showed the performance of hybrids output are result of both GCA and SCA. So based on GCA selection in maize hybrid breeding, the choice of SCA should be strengthened.4. The broad sense heritability and narrow sense heritability of ear length, rows per ear and unit weight were high, and the additive effect was bigger than the non-additive effect, they were affected by the environments slightly, they should be selected at early generations when a population was used to derive inbred lines. The situation of kernel length, shelling percentage and kernel weight100-kernel were just the opposite, they should be selected at later generations. Sterile length, kernels per row, grain yield, plant high and ear high were higher in broad sense heritability but lower in narrow sense heritability, and they were accessible to the environment, so they were not to be selected in early generations.5. For the 31 inbred lines analyzed with 40 primers, the primers were distributed across the 10 maize chromosomes. A total of 198 alleles were detected with the number of alleles per locus ranging from 2 to 9, with an average of 4.950. Information content (PIC) values were 27.310 in total, ranged from 0.264 to 0.862 per locus, with an average 0.683. The results showed that the primers selected had high polymorphism for this study.6. The SSR analysis results showed that the genetic similarity (GS) in 31 inbred lines was ranged from 0.520 to 0.808 with an average 0.642, suggested that genetic diversity was revealed among the inbred lines in this study. GS were used to assign inbred lines to groups by UPGMA,31 inbred lines can classified into five groups based on the GS was 0.683, and the Group III can classified into three subgroups. According to the classification results, in the 7 synthesized corn populations, there was 6 inbred lines were classified into tropical gerplasm,2 inbred lines were classified into Lancaster group,3 inbred lines were classified into tangsipingtou group.1 inbred lines were classified into Reid group, while the other nine inbred lines were classified into other groups. Some inbred lines from same synthesized corn population were not classified into same groups because of the similar genetic background.7. Analysis the heterotic patterns of 20 crosses with the best grain yield, the predominant heterotic pattern was Reid x other groups, while the Lancaster x other groups was below. In addition, Reid x Tropical group, Lancaster x Tropical group and Lvdahonggu x Tropical group were also the good heterotic patterns with good grain yield. The results indicated that good heterosis was found in different groups, and we can get the good crosses between Tropical gerplasm and other three groups (Reid, Lancaster and Lvdahonggu). It proved the opinion that'Tropical x Temperate'was the main heterotic pattern in southwest China corn belt which was mentioned by Rong.
|
PDF Full Text Request