Nanofertilizers as a sustainable strategy to mitigate abiotic stress and enhance plant growth in semi-arid regions: a review

Semi-arid agricultural systems are constrained by water scarcity, salinity, high temperatures, and low soil fertility, which reduce nutrient availability and crop productivity. Nanofertilizers have been proposed as tools to improve nutrient use and crop performance under such stresses, but their effectiveness varies with formulation, particle properties, dose, application method, crop species, soil characteristics, and environmental conditions. This review synthesizes recent evidence on the role of nanofertilizers in enhancing crop tolerance to drought, salinity, and other abiotic stresses in semi-arid regions. Studies were selected using predefined criteria, focusing on agronomic, physiological, biochemical, and molecular responses. The reviewed literature indicates that silicon-, zinc-, iron-, and NPK-based nanofertilizers can improve nutrient uptake, photosynthesis, antioxidant activity, osmotic adjustment, ion homeostasis, root growth, and biomass or yield under specific conditions. However, these effects are highly context-dependent, and evidence for molecular mechanisms remains limited compared with physiological observations. Claims regarding controlled nutrient release, reduced fertilizer inputs, environmental benefits, and soil improvement cannot be generalized across all nanofertilizer types. Moreover, evidence from greenhouse and hydroponic studies greatly exceeds that from long-term field experiments in semi-arid systems. Major knowledge gaps include dose optimization, environmental fate, nanoparticle persistence, non-target toxicity, economic feasibility, and regulatory frameworks. Overall, nanofertilizers show promise for improving crop management under semi-arid conditions, but their sustainable application requires standardized methodologies, long-term field validation, life-cycle assessment, and formulation-specific safety evaluation.