Spatial distribution of maize grain quality and its influence by climatic factors across China

Maize (Zea mays L.) grain quality is an important economic trait directly determining the market price and application value of maize. In this study, maize grain starch, protein, oil, fiber concentrations, and bulk density were investigated based on a multi-site experiment across China to determine the regional distribution trend of grain quality and its influencing factors. It showed that the mean starch, protein, oil, fiber concentrations, and bulk density in China were 73.4%, 9.5%, 4.2%, 3.6%, and 77.2 kg hL(-1), respectively. Overall, each nutritional composition concentration did not show the same spatial distribution as grain yield that was in the order of Northwest (NW) > North (NM) > Huanghuaihai (HM) > Southwest (SW) maize region. The starch and protein concentrations were highest in SW and HM, respectively. The oil concentration was lowest in NW. The interregional difference in bulk density was not significant. As for cultivars, the starch and oil concentrations of ZD958 were higher than that of XY335 in each region, but the protein, fiber concentrations, and bulk density appeared to be the opposite trend. Correlation analysis indicated that the fiber concentration and bulk density were positively correlated with grain yield. The protein, oil, and fiber concentrations were negatively correlated with starch concentration. Among the considered climatic factors, the protein, fiber concentrations, and bulk density were mainly positively affected by temperature factors in China. The results provide a reference for the division of maize advantageous quality regions and the construction of high-yield and quality technology model in typical ecological regions.