| Tropical and subtropical corn as main parent germplasm population were often utilized for breeding in recent years. BT-1 derived from the tropical germplasm show high resistance to Fusarium ear rot and excellent agronomic characters in maize. Genetic analysis of agronomic traits are significance for maize improvement of breeding. In this research, two hundred and thirty recombinant inbred lines (RILs) derived from the cross BT-1×N6 were used for agronomic traits evaluation; a genetic linkage map with 207 SSR markers was constructed for quantitative trait loci (QTL). QTLs were conducted by composite interval mapping (CIM) method in agronomic traits, interactions of QTLs were identified using based on mixed composite interval mapping (MCIM) method. At the same time, verification of QTLs for Fusarium ear rot was conducted in the 3 populations. The main results were as follows:1. Under three environments, transgressive segregation was observed for eight ear traits, three plant traits and three growth stage traits in the RIL population. Normal distribution was observed for all traits. The heritability of thr traits were all high, ranging from 67.8%-84.2%, 92.0%-93.3% and 85.3%-86.2%, respectively. Analysis of variance (ANOVA) showed significant difference among all the traits.2. A total of seventy-eight QTLs were identified for ear traits under the three environments and in the combined analysis. Contribution of single QTL to phenotypic variation varied from 4.04% to 32.70%. Of these, eight QTLs(qEN5,qEN2-3,qKR6-1,qED5-3,qHKW2-1,qCD4,qCD6-2 and qCD5-2)were common under two or three environments. thirty-nine QTLs were up to 10% of the phenotypic variation. The increasing ear effects of thirty-five QTLs came from the female parent BT-1, others came from N6.3. A total of sixty-nine QTLs were identified for the agronomic traits under the three environments and in the combined analysis using the composite interval mapping method, which accounted for 3.37%-35.18% of phenotypic variation among the different traits. Of these, thirteen QTLs (qPH2,qPH9,qEH2,qEH1-2,qTBN4-1,qTBN5-1,qTBN5-3,qTE1,qTE2-1,qSE1-1,qSE2-1,qAN1 and qAN2) were common under two or three environments with higher contributions and stability. A few QTLs controlling the growth stage traits (days to tasseling, days to silking, days to anthesis) located at the same marker loci or in the same marker confidence intervals on chromosome 1 (1.05-1.06) and 2 (2.03), the key regions were showed.4. Four pairs of epistatic QTLs were identified for the ear traits, all epistasis QTLs were additive×additive effects and varied from 0.78% to 1.68%. Nine pairs of epistatic QTLs were identified for the agronomic traits, which can account for 0.44%-1.59% of phenotypic variation. Most of epistatic QTLs effects in a single locus was not significant, but can affect the expression of traits with the main effect QTL interactions.5. Using marker-assisted selection with phenotype evluated, the resistant parent BT-1 backcrossed to the susceptible inbred line N6, Xi502 and Xiongzhang, respectively. The near isogenic lines with the QTLs were breeded. The QTLs for resistance to Fusarium ear rot were verified. The result indicated that the QTLs for kernel resistance on chromosome 4 stable in the two populations. The QTLs for cod resistance were located in umc1954-umc1539 on chromosome 3 in BC5F2 which derived from backcross BT-1 to Xiongzhang.
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