Enhancing drought tolerance in wheat using zinc and iron nanoparticles: Implications for sustainable industrial crop productivity

Drought is a major constraint to wheat productivity, reducing growth, water balance, and photosynthetic capacity. This study evaluated the effects of zinc oxide nanoparticles (ZnO-NPs; ∼43 nm) and iron oxide nanoparticles (FeO-NPs; ∼58 nm) on three wheat cultivars (Johar-16, Faisalabad-08, and Aas) under hydroponic (20 % PEG-6000) and pot (irrigation withholding) experiments. Objectives were to quantify drought-induced changes, assess whether NPs alleviate these effects, and identify cultivar-specific responses. Drought reduced shoot length from 67.3 ± 1.8 cm to 51.2 ± 2.1 cm, relative water content (RWC) from 89.6 ± 2.4 % to 72.3 ± 2.7 %, and increased proline twofold (3.24 ± 0.18 vs. 1.61 ± 0.11 µmol g⁻¹ FW). ZnO-NPs (60 ppm) were most effective in enhancing shoot length (66.7 ± 1.9 cm in Johar-16), improving root biomass (4.12 ± 0.14 g), and restoring RWC (88.4 ± 2.2 %). FeO-NPs showed stronger effects on shoot dry weight (9.73 ± 0.27 g) and grain yield, particularly in Faisalabad-08, which produced 74 % higher yield compared to drought controls. Johar-16 demonstrated the strongest physiological adjustment, especially osmolyte accumulation and water retention, while Faisalabad-08 excelled in yield stability, and Aas displayed moderate responses. Hydroponic trials highlighted physiological mechanisms of NP action, whereas pot experiments reflected agronomic performance under soil–water limitations. Overall, ZnO-NPs were more effective for growth recovery, FeO-NPs for yield improvement, Johar-16 for drought physiology, and Faisalabad-08 for yield resilience. These findings highlight the potential of nanoparticle-based interventions to strengthen wheat resilience under water-limited conditions. • ZnO nanoparticles (60 ppm) improved biomass and chlorophyll in drought. • Johar-16 showed higher osmolyte buildup than Faisalabad-2008 and Aas. • Hydroponics gave precise NP effects; pots reflected soil-water balance.