A recent study published in Scientific Reports by Muhammad Zeeshan Mansha, Amr Elkelish, and colleagues investigated a potent strategy for climate-resilient agriculture: the synergistic application of biochar (BC) and sodium hydrosulfide (NaHS) to enhance drought tolerance in maize. Drought is identified as a major abiotic stressor that significantly limits global maize productivity, severely threatening crop production in the context of climate change. This research demonstrated that while drought stress severely diminishes growth, photosynthetic pigments, stomatal conductance, and leaf water content, simultaneously increasing oxidative damage, a combined application of biochar and NaHS can effectively alleviate these detrimental effects.

The experiment was conducted under greenhouse conditions, utilizing three levels of drought stress, with the most severe stress being 35% ± 5% of field capacity. The integrated treatment using 3% biochar mixed with pot soil and a foliar application of 0.1 mmol L−1 NaHS (T5​) proved to be the most effective in mitigating drought-induced stress. This combined approach resulted in substantial improvements in the maize plants’ physiological performance and growth. Biomass and growth traits, including plant height, ear diameter, and ear length, were enhanced by 20% compared to the control under drought-stressed conditions. Furthermore, the combined treatment significantly boosted photosynthetic performance by more than 50% and increased leaf water content by 38%. The best level of combined biochar and NaHS application led to a maximum increase in total chlorophyll by 138.68% and photosynthetic rate by 89.74%, relative to the control group under drought-stressed conditions.

The mitigation of drought stress by the combined treatment is attributed to a dual mechanism. Biochar functions as a soil conditioner, enhancing water retention and nutrient availability, which physically alleviates water stress. Sodium hydrosulfide, acting as a donor of hydrogen sulfide (H₂​S), a critical signaling molecule, improves the plant’s internal defense mechanism. H_2​S helps to mitigate oxidative damage by activating antioxidant enzymatic and non-enzymatic pathways, protecting cellular structures from reactive oxygen species (ROS) damage, and maintaining the photosynthetic machinery. The combined effect ensures better water uptake and nutrient utilization, sustaining metabolic activity even under water-limited conditions.

Drought stress typically elevates the levels of enzymatic antioxidants and ROS markers as the plant attempts to combat oxidative stress. However, the optimal combined biochar and NaHS treatment significantly reduced the levels of stress-related biochemical markers. For instance, it decreased the accumulation of malondialdehyde (MDA), a marker for lipid peroxidation and membrane damage, by 32.82%, and electrolyte leakage by 57.21% compared to the control under drought. This stabilization of the cellular environment is crucial for maintaining plant vigor and productivity. Additionally, the integrated treatment significantly reduced the stress-induced accumulation of osmolytes and secondary metabolites, such as proline and soluble sugars, suggesting a more regulated stress response and osmotic adjustment. The combined application reduced proline by 66.26% and soluble sugar by 55.94% in maize plants compared to the untreated control.

The study confirms a strong synergistic protective role of biochar and NaHS. The application of biochar creates a stable, favorable soil environment, while the application of NaHS enhances the plant’s cellular capacity to tolerate and recover from stress. This integrative approach resulted in improvements across all assessed parameters—growth, physiological, and biochemical—demonstrating its potential for practical application in sustainable agriculture, particularly in regions where drought is a persistent challenge. The researchers recommend that future field-scale trials and molecular investigations should be conducted to fully validate these findings and elucidate the underlying molecular mechanisms of this stress-mitigation effect.

Source: Mansha, M. Z., Elkelish, A., Ikram, K., Abbas, T., Aatif, H. M., Amin, M. A., Hanif, C. M. S., Ashraf, K., Al-zharani, M., Rudayni, H., Atakpama, W., & Zaman, Q. u. (2025). Synergistic application of biochar and sodium hydrosulfide enhances maize drought tolerance through improved physiological performance and stress mitigation. Scientific Reports, 15(43558).