Quantitative trait loci mapping for kernel row number using chromosome segment substitution lines in maize

Unveiling the genetic architecture of grain yield and yield-related traits is useful for guiding the genetic improvement of crop plants. Kernel row number (KRN) per ear is an important yield component, which directly affects the grain yield of maize. In this study, we constructed a set of 130 chromosome segment substitution lines (CSSLs), using Nongxi531 as the donor parent and H21 as recipient parent, by continuous backcrossing and selfing. In total, 11 quantitative trait loci (QTL) were detected for KRN by stepwise regression under 3 environmental settings, with 9.87-19.44% phenotypic variation being explained by a single QTL. All 11 QTL were also detected by single-factor ANOVA across the 3 environments tested. Of these 11 QTL, 4 were identified across more than 2 environments, indicating that they are authentically expressed under different environments to control the formation and development of KRN in female maize inflorescences. The CSSLs harbored a greater number of favorable alleles for KRN compared to the H21 line, and could be employed as improved H21 lines in maize breeding programs.