| The superior maize inbred lines QB506 and QR273 as the acceptors, which are parents of the superior maize hybrid Jinyu506. QB506 was improved by 5 superior hybridizes and inbred lines PH6 WC, and the superior maize inbred line QR273 was crossbred with 4 superior maize inbred lines from Suwan, from which numbers of superior inbred lines had been bred. The experimental materials were QB506 including its 9 QB506-derived lines and QR273 including its 9 QR273-derived lines were used as the experimental materials to hybridize 100 groups with the NCⅡdesigns. QB506 and its 19 QB506-derived lines, QR273 and its 28QR273-derived lines, as well as 5 donor inbred lines and 6 backbone corn inbred lines were chosen as molecular biology experiments materials with the method of Partially Balanced Lattice Design. Through the analyze of combining ability and genetic diversity with SSR molecular markers, the effects of genetic improvement on QB506 and QR273 contributed by different donor parents come out. The main results were summarized as following:1.The variance analysis for main agronomic traits of Guiyang, Dejiang and Luoping showed that the significant or extremely significant difference can be the result of different experimental combinations, different groups and different sites. The variance of combination × site shows that except the ear row number, the other traits are appropriate or equal to the standard, which indicate that the phenotype not only effected by genotype, but also by ecological conditions, weather conditions, other environmental factors and the interaction between genes and environment. The difference of the general combining ability(GCA) and the special combining ability(SCA) of parents were significant.2.From the GCA analysis of 20 inbred lines, the yield general combining ability of QB506-derived lines are significantly higher than that of QB506, except QB1584.The yield general combining ability of QB2208, QB2182 and QB2232(QR273-derived lines) are higher than that of QR273.3.The yield SCA of the 100 hybridized crosses range from-0.5728 to 0.5396, 48 crosses have the positive effects, the SCA of the control group(QB506×QR273) is-0.0553, The yield SCA of 61 hybridized crosses higher than that of CK. The max SCA is 0.5396 of QB1495×QB2038, which is 0.5949 higher than that of CK.4.The total combining ability(TCA) was consistented with the yield of 100 hybridized crosses. The TCA of CK is-0.1587, 48 hybridizedcrosses have the positive effects, 63 hybridized crosses are higher than the CK. QB2398×QB2232 is 0.8299 as the maximum TCA. And QB1584×QB2163 is-0.7590 as the minimum TCA. The yields of 42 hybridized crosses are 5% more than CK. There are 26 hybridized crosses yield 10% more than the CK. All the results of GCA,SCA and the yield showed that:the comprehensive characters of QB506-derived lines, QB2398 and QB2425 are better than QB506. Similarly, QB2182, QB2208, and QB2232 are better performance than QR273. The comprehensive characters of QB2398×QB2232,QB2398×QB2208,QB2425×QB2232, QB2398×QB2182 and QB2425×QB2182 are better than CK.5.Compared with the CK, the average yield of hybridized crosses group with each QB506-derived lines showed that: except QB1584, the mean yield of hybridized crosses group with QB506-derived lines is higher than that of CK; the mean grains rate of hybridized crosses group with QB506-derived lines except QB1540 and QB1584 are higher than that of CK; the grain moisture content of hybridized crosses group with QB506-derived lines except QB1540 and QB1636 are lower than CK. The result of the average yield of hybridized crosses group with each QR273-derived lines compared with the CK showed that: the mean yield of hybridized crosses group with QR273-derived lines except QB2229 and QB2163 are higher than that of CK; the mean grains rate of hybridized crosses group with QR273-derived lines except QB1743, QB2163 and QB2038 are higher than that of CK; the grain moisture content of QR273-derived lines except QB1743 are lower than CK. All in all, the effects are good to improve the grains rate and grain moisture content of QB506 and QR273 by different donors.6.The result showed that: 42 SSR markers were polymorphic and scored with high confidence among our collection. 248 alleles have been got, and the average of alleles is 5.9, ranging from 2 to 9 alleles. The Polymorphism Information Content(PIC) values range from 0.0573 to 0.7334, with an average of 0.4669. The Marker Indice(MI) averages 3.0523,ranging from 0.1243 to 6.6007. The amplitude of variation in these three genetic diversity index values is rather large, which indicate that the genetic diversities of the inbred lines of the 60 maize inbred lines areabundant.7.The correlation between the yield and the 100 grain weight or GD are not significant. There are significant positively correlation between the yield and the ear length, ear diameter genetic, ear row number, or grain per-row. There are significant negative correlation between the yield and length of ear bald top. The correlation between the GD and the ear length or length of ear bald top or ear row number is positive but not significant. Others are negative correlation with GD, especially, ear diameter genetic and 100 grain weight reached the significant or extremely significant negative correlation. The results of this study showed that GD with SSR between parents is not enough to predict the heterosis of hybridized crosses. |
PDF Full Text Request