QTL mapping and genetic analysis for maize kernel size and weight in multi-environments

Kernel size and weight are important agronomic traits, as well as crucial traits that influence grain yield in maize. In the present study, 150 F₇ recombinant inbred lines derived from a cross 178×K12 were evaluated for kernel length (KL), kernel width (KW), kernel thickness (KT), and 100-kernel weight (HKW) across seven environments. Natural variations in KL, KW, KT, and HKW were observed in the population. A set of quantitative trait loci (QTLs) for the kernel-related traits were identified by inclusive composite interval mapping method. For the four kernel traits from seven environments and the best linear unbiased prediction data, a total of 52 QTLs were detected, which distributed on all chromosomes except chromosome 6. The LOD values ranged from 2.52 to 8.91, the additive effect from ??2.22 to 1.37, and the range of individually explaining phenotypic variation was from 5.8 to 23.49%. Amongst these QTLs, most were detected only in one or two environments. Three stable QTLs, qKL4-1 at bin 4.07/4.08, qKW4-2 at bin 4.06 and qKT2-1 at bin 2.02/2.03, were identified across at least three environments. Besides, several overlapping QTLs associated with multiple traits were identified. For example, qKW3-1 for KW and qHKW3-1 for HKW were located in the same marker interval at Bin 3.01/3.02. These stable QTLs and overlapping QTLs found in this study will contribute to the understanding of genetic components of grain yield and provide the foundation for molecular marker-assisted breeding in maize.