Nanomaterials for Soybean Growth Promotion and Stress Tolerance: A Review of Mechanisms and Applications

Soybean (Glycine max) is a globally important source of protein and oil, and its capacity for biological nitrogen fixation (BNF) underpins its strategic role in sustainable agriculture. However, BNF efficiency is highly sensitive to abiotic stresses, and conventional agronomic interventions struggle to simultaneously optimize nodulation, nitrogenase activity, and stress resilience. Agricultural nanotechnology offers a unique avenue to address this bottleneck by modulating the tripartite nanomaterial–rhizobium–soybean interaction at multiple scales. This review systematically examines (1) nanomaterial design strategies tailored to the rhizosphere and nodule microenvironments; (2) the ‘Rhizosphere–Nodule–System’ (RNS) cascade model, which integrates rhizosphere interfacial events, nodule metabolic reprogramming, and systemic stress signaling; and (3) field-level efficacy, genotype-dependent responses, and barriers to scalable application. By elucidating the mechanistic logic by which nanotechnology coordinates BNF enhancement with abiotic stress tolerance, this framework provides theoretical support for the targeted deployment of nano-agricultural technologies in soybean production systems.