Context Understanding the effects of genetic and meteorological factors throughout the planting dates is essential to breeding genetic improvement strategies focused on grain yield and quality. Aims The purpose of this study was to identify the genetic and environmental factors associated with variation in grain yield and contents of crude protein and starch in maize (Zea mays) grains across different sowing environments. Methods A total of 78 maize genotypes were evaluated on 10 sowing dates in 2021, 2022, and 2023. Grain yield was corrected to 13% moisture content, while 100-g samples were dried, ground, and analyzed by near-infrared reflectance spectroscopy, allowing the determination of crude protein and starch contents. The analyses included regressions, decision trees, and random forest to identify factors that determine yield, protein, and starch. Differences between levels of qualitative factors were assessed using the Scott-Knott test, and quantitative factors were assessed using polynomial regressions. Key results Biotechnological events and global solar radiation during the vegetative and reproductive stages are the most relevant variables in explaining grain yield. The genetic basis combined with solar radiation and rainfall during the vegetative stage determine variations in crude protein levels. Sowing date, rainfall during the reproductive stage, and maximum air temperature during the vegetative stage are the main variables associated with starch content. Conclusions Grain yield and nutritional traits are determined by combinations of genetic and environmental factors. Implications The results may support regional genotype selection and sowing-date management strategies aimed at improving maize grain yield and nutritional quality under the environmental conditions evaluated.
Loro et al. (Mon,) studied this question.