Fertilization regulates maize nutrient use efficiency through soil rhizosphere biological network and root transcriptome

Fertilization impacts soil biological communities, affecting their diversity, structure, and composition. These communities are crucial in rhizosphere microenvironment, influencing root genes expression and nutrient absorption/utilization of the crop. This study investigated the effects of different fertilization methods on rhizosphere biological network, transcriptome responses in maize roots, fertilizer use efficiency and maize yield in a long-term field experiment. The results revealed that the BCNPK (adding biochar to synthetic fertilizers) treatment exhibited the highest maize yield, which was 21-23 % higher than other fertilization treatments. Additionally, the BCNPK and RSDNPK (partial synthetic nitrogen replacement with crop residue) demonstrated significant advantages in minimizing nitrogen loss and enhancing nitrogen absorption and utilization efficiency. Compared to NPK (synthetic fertilizers), BCNPK, and OMNPK (partial synthetic nitrogen replacement with pig slurry), the network complexity of bacteria and fungi decreased under the RSDNPK treatment. The co-occurrence network analysis revealed that fertilization modulated the biological community's composition and abundance, which led to the formation of distinct ecological clusters in rhizosphere biological network. Furthermore, the abundance of these ecological clusters exhibited a significant correlation with crop yield and nutrient uptake. Structure equation modelling demonstrated that alterations in soil physicochemical properties significantly affected soil biodiversity and genes expression in maize root. Furthermore, soil biodiversity significantly correlated with the maize yield, underscored the pivotal role of rhizosphere organisms in determining crop yield. These findings serve as a foundational reference for subsequent researches on the mechanistic interactions between rhizosphere organisms and plants.