Climate warming extends the effective growth period of winter wheat and increases grain protein content

Climate warming causes an impact on the protein supplied to grains by affecting the winter wheat growth period and yield formation; however, research on the effects of warming on protein formation of winter wheat grains is limited. We investigated this phenomenon by conducting no-tillage (NT) and conventional tillage (CT) field warming trials in the North China Plain for four consecutive years (2017–2020). The results showed that warming significantly advanced the re-greening period and extended the effective growth period of winter wheat. Warming also improved the physiological characteristics of winter wheat as well as N accumulation in the stems and leaves during anthesis, facilitating the transport of N to the grains. Moreover, warming reduced the number of fertile spikelets in winter wheat and diverted N that would otherwise be supplied to produce more grains to the final effective grains, resulting in a significant increase in grain protein content (15.75% in CT, 19.11% in NT; p < 0.05). Our findings suggest that winter wheat can partially counteract the adverse effects of climate warming on its grain protein content. This study further elucidates the effect of climate warming on the protein content of winter wheat grains.