Identification of quantitative trait loci (QTLs) for flowering time using SSR marker in maize under water stress

The selection of reduction of anthesis-silking interval (ASI) in maize breeding is an efficient way to develop maize varieties more tolerant to dry growing conditions. Characterization of the quantitative trait loci (QTL) that controlled the flowering time will be helpful for selection in maize breeding. In this study, flowering time of individuals in a 234 F-2:3 family, derived from the cross between inbred lines X178 and B73, was evaluated under well-watered and water-stressed conditions at the same location. SSR (microsatellite) was used to identify flowering time QTL. The results showed that the broad-sense heritability for male flowering time (MFT), female flowering time (FM and ASI were 0.72, 0.72 - 0.74 and 0.40 - 0.42, respectively, and ASI was significantly correlated to FFT. Under water-stressed condition, 9, 6 and 6 QTLs were identified for MFT, FIT and ASI, respectively, and individual QTL accounted for approximately 2.88% - 31.65% of the phenotypic variation. Some QTLs for NUT were mapped overlapping with those for FFT and ASI. One QTL on chromosome 9 (near nc134) had the strongest effect on NOT, FTT and ASI. It was suggested that the epistasis contributed to the phenotypic variation of flowering time.