Biochar and zinc oxide nanoparticles partnership: a multi-faceted strategy to enhance rice productivity and remediate antimony polluted soils

Background Antimony (Sb) is a toxic metalloid that poses a significant threat to living organisms and ecosystem sustainability. Biochar (BC) and zinc oxide nano-particles (ZnO-NPs) are promising amendments to mitigate heavy metals toxicity. However, the potential role of BC and ZnO-NPs in alleviating the Sb toxicity remains unexamined. To address this gap, the present study investigated how BC and ZnO-NPs mitigate Sb toxicity in rice. Methodology The study included eight different treatments: control, biochar (2%), ZnO-NPs (100 mg L − 1 ), BC + ZnO-NPs, Sb stress (250 mg kg − 1 ), Sb stress + BC (2%), Sb stress + ZnO-NPs, and Sb stress + BC (2%) + ZnO-NPs. Results Antimony suppressed rice growth and yield by inducing oxidative stress (increased hydrogen peroxide (H 2 O 2 ) and electrolyte leakage), enhancing soil Sb availability and its accumulation in plant tissues, while reducing hormones synthesis and soil nutrients availability. Biochar + ZnO-NPs markedly enhanced the rice yield by decreasing H 2 O 2 synthesis (26.06%), EL production (25.68%), soil Sb availability (41.80%) and increasing antioxidants activities, formation of iron plaque in roots (63.60%) and soil nutrients availability. Additionally, BC + ZnO-NPs upregulated the antioxidant genes ( OsAPx6 , OsCAT , OsPOD , and OsSOD ), and downregulated the expression of OsSMP and OsMTP1 genes associated with Sb transport, thus helping to counteract Sb toxicity. Conclusion These findings suggest that the BC + ZnO-NPs can effectively mitigate the Sb toxicity and improve rice productivity. These findings provide insights to develop the measure for remediating Sb-polluted soils, while simultaneously increasing the safe and sustainable crop production.