Effects of Root Exudates on Ecological Function and Nitrogen Utilization Strategy of Orchard Multi-Planting System

While root exudates play a crucial role in maintaining ecosystem balance and promoting plant growth, existing research primarily focuses on single ecosystems (e.g., field crops), with systematic investigations of their ecological functions in compound cropping systems, particularly nitrogen (N) cycling mechanisms in orchard multi-cropping systems, remaining limited. This review focuses on the N impact mechanisms mediated by plant root exudates in orchard ecosystems, emphasizing how root exudates optimize soil N activation, absorption, and utilization efficiency by modulating rhizosphere processes (e.g., nitrogen mineralization, root architecture remodeling). Studies indicate that the changes in orchard ecosystem function mediated by organic acids and flavonoids root exudates can significantly reduce nitrogen loss risks and increase the soil nitrogen turnover rate by lowering pH-activated nutrients, balancing the C:N ratio, and immobilizing microbial communities. This process also involves the coordinated regulation of nitrification, denitrification, and microbial fixation. Future research should prioritize investigating the interaction networks and regulatory mechanisms between root exudates of associated orchard crops and N-fixing microorganisms. This research direction will provide a scientific basis for improving the N use efficiency in orchard crops, optimizing fertilizer reduction techniques, and reducing chemical fertilizer usage, providing significant implications for achieving sustainable agricultural development. The theoretical support offers important scientific and practical value for advancing green and sustainable agriculture.