Nanomaterial-Mediated Modulation of Plant Functional Traits and Rhizosphere Processes: Mechanistic Insights into Plant Stress Physiology

Agricultural systems increasingly face interacting abiotic and biotic stresses driven by climate change and soil degradation. Plant performance under such conditions is determined by coordinated networks of functional traits governing resource acquisition, allocation, and defense. These traits also structure plant-associated microbiomes, whose activities influence nutrient cycling, stress buffering, and disease suppression. This review synthesizes current evidence that agricultural nanomaterials enhance crop stress resilience primarily by reprogramming plant functional trait networks and, through them, modulating microbiome dynamics. We analyze how nanomaterial physicochemical properties including size, surface chemistry, dissolution behavior, and redox activity determine their bioavailability and interaction with plant tissues. These interactions influence key trait categories such as root architecture, hydraulic regulation, nutrient acquisition efficiency, photosynthetic performance, and antioxidant capacity. Trait-level modulation underpins improved tolerance to drought, salinity, temperature extremes, heavy metal toxicity, and pathogen pressure. Furthermore, nanomaterial-induced shifts in plant traits reshape rhizosphere and endophytic niches, reinforcing beneficial microbial functions including nutrient mobilization, hormone regulation, pathogen suppression, and soil structural stabilization. This review proposes a trait-centric framework in which nanomaterials act as regulators of plant functional organization rather than simple growth stimulants. Future research should prioritize trait-based screening, microbiome functional monitoring, and predictive nano–ecological modeling to enable safer and more effective nanotechnology deployment for sustainable crop production.