The effect of nitrogen reduction combined with biochar application on the photosynthetic function of tobacco leaves

Nitrogen is the primary limiting factor for crop yield formation. However, excessive application of nitrogen fertilizer not only leads to a decrease in nitrogen utilization efficiency, but also causes serious environmental problems. Therefore, how to balance environmental protection and crop yield when applying nitrogen fertilizer is an important challenge currently faced in agricultural production. Biochar, as a soil amendment, has been widely used in agricultural production. This study used 'Longyan 101' tobacco as the experimental material and explored the effects of nitrogen reduction treatment (reducing conventional nitrogen application by half) and combined application of biochar (20 kg/hm2) on tobacco photosynthesis under field experimental conditions. Transcriptome sequencing technology was used to study the changes in the expression levels of photosynthesis-related genes. The results indicate that: reducing the application of nitrogen fertilizer reduces the photosynthetic capacity of tobacco and inhibits its growth, while applying biochar can to some extent alleviate the adverse effects of insufficient nitrogen fertilizer. The results of this experiment have laid the foundation for the rational application of nitrogen fertilizer and the green development of tobacco agriculture.