Effects of climactic warming on the starch and protein content of winter wheat grain under conservation tillage in the North China Plain

Climate warming is expected to affect global food security and nutritional quality, particularly winter wheat grain protein content. No-tillage (NT) agriculture may be an effective option to mitigate the effects of climate warming; however, the associated mechanism remains unclear. Therefore, this study investigated the effects of warming under NT and conventional tillage (CT) treatments on the physiological growth processes, yield, yield components, plant nitrogen metabolism, as well as grain protein content and fractions of winter wheat in the North China Plain for four consecutive years (2021-2022). The results showed that temperature increases under the NT and CT systems significantly impacted winter wheat growth and development, prolonged the effective reproductive period, and increased the leaf area index, photosynthesis rate, and aboveground dry matter mass in the pre-flowering stage. Hence, the temperature increase and tillage treatment affected the components and yield of winter wheat. The number of fruiting spikelets decreased significantly, and the number of grains and thousand-grain weight increased under the CT and NT systems. Meanwhile, the elevated temperature significantly increased the winter wheat yield by 11.4% (CT) and 62.3% (NT) compared with the control group. Temperature increases also significantly increased winter wheat seed protein content by 10.88% and 30.91% under CT and NT, respectively. The effects of warming and tillage treatments on seed protein fractions were more complex, with warming under CT reducing the albumin, globulin, and glutenin contents, whereas warming under NT increased the contents of all four protein fractions. This study provides a scientific basis for the mechanism underlying climate warming effects on protein content and fractions of winter wheat grains.