Improved mineral nutrient absorption and targeted tissue deposition via nano-fertilizers boost drought tolerance in maize ( Zea mays L.)

Drought stress poses a critical threat to maize (Zea mays L.) production by disrupting nutrient uptake, reducing metabolic efficiency, and impairing growth and yield. This study evaluated the effectiveness of foliar-applied nano-fertilizers – nano-zinc oxide (ZnO), nano-iron oxide (Fe₂O₃), and nano-silica (SiO₂) – in enhancing drought tolerance in maize under well-watered, moderate, and severe drought conditions over two growing seasons (2023–2024). Using a randomized complete block design with a factorial arrangement, we assessed physiological and biochemical responses to stress and treatment. Drought significantly reduced nitrogen and protein content, induced oxidative stress (elevated H₂O₂), and disrupted mineral balance. Nano-fertilizer application, particularly nano-ZnO and nano-Fe₂O₃, significantly improved nitrogen assimilation, enhanced proline accumulation, and reduced oxidative damage. These treatments also improved phosphorus and potassium retention, while nano-SiO₂ reduced sodium accumulation under drought. Additionally, all nano-treatments increased micronutrient concentrations (Ca, Zn, Fe, Cu, Mn), supporting metabolic resilience. The combined application of all three nano-fertilizers demonstrated synergistic effects in enhancing osmotic adjustment, antioxidant activity, and overall drought resilience. These findings highlight the potential of nano-fertilizers as sustainable tools to mitigate drought impacts and maintain maize productivity under water-limited conditions. Future research should focus on field-scale validation, dosage optimization, and environmental risk assessments of nano-fertilizer use.