Applications of soil amendments for enhanced phytostabilization and wheat growth development under combined drought...

Heavy metal contamination combined with drought stress severely limits wheat productivity and undermines soil health. This study aimed to evaluate the effectiveness of iron modified stilbite zeolite (Fe-SZ) and nanobiochar (Fe-NB) in improving heavy metal mitigation and drought tolerance in a subsequent wheat crop (Triticum aestivum L.) grown in previously contaminated soil. A controlled pot experiment was conducted using three Fe-NB application rates (Fe-NB₁ = 0%, Fe-NB₂ = 4%, and Fe-NB₃ = 8% w/w) and three Fe-SZ particle sizes, (Fe-SZ₁ = 0.5 mm, Fe-SZ₂ = 1 mm, and Fe-SZ₃ = 2 mm), with drought stress imposed 30 days after planting. The most effective treatments significantly improved plant growth and reduced toxic metal uptake. Fe-SZ₂ decreased arsenic and lead concentrations in plant tissues by 31.33% and 22%, respectively, while Fe-NB₃ (8% w/w) reduced them by 51.13% and 34%. Cadmium levels were reduced by approximately 50% across Fe-SZ and Fe-NB treatments, and Fe-SZ₂ further lowered soil Hg by 74.5%. Fe-NB₃ consistently provided the strongest overall benefits and improvements were reflected in greater shoot biomass, enhanced root growth, and increased chlorophyll content, although some treatments increased metal bioavailability. These findings demonstrate that Fe-SZ and Fe-NB can serve as effective amendments for reducing heavy metal stress and improving wheat resilience under water-limited conditions.