Identification and stability of QTLs for grain traits in the elite wheat variety ‘Chuanmai104’

Chuanmai104 (CM104), an elite wheat (Triticum aestivum L.) variety that currently produces the highest yield per unit area in southwestern China, plays a critical role in wheat production. The high quality and stability of grain traits are important factors that ensure the high, stable yields of CM104 in different production areas. In this study, six grain traits of CM104 sampled from 19 environments in five provinces of China during 2018–2022 were evaluated. The traits comprised thousand-kernel weight, grain length, grain width, grain length–width ratio, grain circumference, and grain surface area. Fifteen quantitative trait loci (QTLs) associated with the grain traits were identified based on a recombinant inbred lines (F_9–10) population derived from the cross between CM104 and the landrace Baimaomai (BMM), nine and six QTLs derived from CM104 and BMM, respectively. Three mainly pleiotropic QTLs derived from CM104, namely QTL10 (grain circumference, grain surface area), QTL11 (grain length, grain circumference), and QTL12 (grain length, grain circumference), were expressed significantly and stably in multiple environments, and explained 3.34–5.06%, 5.32–6.50%, and 6.00–12.13% of the phenotypic variation, respectively. The pyramiding of multiple genes is hypothesized to have contributed to the stability of the CM104 grain traits in different environments. The results provide a basis for future improvement of yield and its stability in wheat.