Mitigating the adverse effect of warming on rice canopy and rhizosphere microbial community by nitrogen application: An approach to counteract future climate change for rice.

The adverse impact of climate change on crop production continues to increase, necessitating the development of suitable strategies to mitigate these effects and improve food security. Several studies have revealed how global warming negatively impacts the grain-filling stage of rice and that this effect could be mitigated by nitrogen; however, the impact of nitrogen application on rice canopy and rhizosphere microbial communities remains unclear. We conducted a study using an open-field warming system. Results showed that warming influenced rice canopy by decreasing aboveground biomass and harvest index, whereas nitrogen application had positive effect on rice production under warming conditions by increasing the plant nitrogen content, biomass, harvest index and soil fertilities. Moreover, soil ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3--N) contents were significantly decreased under warming, which were higher after nitrogen application. Notably, warming and nitrogen fertilizer caused 19 % (P < 0.01) and 7 % (P < 0.05) variations, respectively, in the β diversity of the microbial community, respectively. The impact of warming was significant on NH4+-N-related microorganisms; however, this impact was weakened by nitrogen application for microbes in the rhizosphere. This study demonstrated that enhanced nitrogen fertilizer can alleviate the adverse impact of warming by weakening its effects on rhizosphere microbes, improving soil fertility, promoting rice nitrogen uptake, and increasing the aboveground biomass and harvest index. These findings provide an important theoretical basis for developing practical, responsive cultivation strategies.