Synergistic application of biochar and sodium hydrosulfide enhances maize drought tolerance through improved...

Drought is a major abiotic stress limiting global maize productivity. In this study, we evaluated the combined application of biochar (BC) and sodium hydrosulfide (NaHS) as a potential strategy for enhancing drought resilience in maize (cv. Gohar-19) under greenhouse conditions. The experiment comprised of two factors i.e., drought stress including S₁ (85% ± 5% field capacity), S₂ (55% ± 5% field capacity) and S₃ (35% ± 5% Field capacity) and various treatments of BC and NaHS i.e., T_o (control), T₁ (3% biochar), T₂ (0.05 mmol L^- 1 NaHS), T₃ (0.1 mmol L^- 1 NaHS), T₄ (T₁ + T₂) and T₅ (T₁ + T₃). Results revealed that drought stress significantly reduced growth traits, photosynthetic pigments, photosynthetic rate, stomatal conductance, and leaf water content, while increasing oxidative damage, osmolyte accumulation, and lipid peroxidation. By contrast, the integrated treatment of biochar and NaHS (0.01 mmol L⁻¹) significantly alleviated these negative effects, improving biomass and growth by ~ 20%, increasing photosynthetic performance by more than 50%, and enhancing leaf water content by 38%. Furthermore, this combined treatment reduced stress-related biochemical markers, including superoxide dismutase, peroxidase, malondialdehyde, and hydrogen peroxide, by over 30%, and led to a significant decline in osmolyte and secondary metabolite accumulation. Correlation and principal component analyses confirmed strong associations among growth, physiological, and biochemical parameters, highlighting the synergistic protective role of biochar + NaHS treatment. These findings provide experimental evidence that this integrative approach can improve maize drought tolerance and productivity in maize, supporting its potential application in sustainable agriculture. Field-scale trials and molecular investigations are warranted to validate these findings and elucidate underlying mechanisms of this stress-mitigation effect.