Marker-assisted backcrossing of maize-inbred lines

We transferred the Hap2 allele into two Hap1 allele-harbored lines (Zheng58 and Chang7-2) that are widely used in Chinese maize-breeding programs, by marker-assisted backcrossing using the NIL^qKNR6 as the donor. Four backcrossing generations followed by two self-crossing generations were performed. Those improved lines were phenotypically evaluated at Wuhan (30.60°N and 114.30°E) in 2017 spring. The field experiments were performed in a randomized block design with three replicates. Each plot consisted of 2 rows, and each row grows 12 individuals. The original hybrid Zheng58/Chang7-2 and improved hybrid Zheng58^qKNR6/Chang7-2^qKNR6 were grown at Wuhan (30.60°N and 114.30°E) in 2017 spring and Zhengzhou (34.75°N and 113.62°E) in 2017 summer. The grain yield-related traits, including EL (cm), KNR, kernel weight (KW, g), and EW (g), were measured. Post hoc test of LSD was used for the data analysis with significant threshold p value < 0.05.