Drought stress represents a major threat to global agricultural productivity, particularly affecting cereal crops such as Sorghum bicolor (L.) Moench. This study investigated the role of silicon (Si) in alleviating drought-induced oxidative stress through the modulation of antioxidant enzyme activities in sorghum seedlings. Using a drought-tolerant Sudanese cultivar (cv. Gadambalia), plants were treated with sodium silicate (1.67 mM) and subjected to osmotic stress via sorbitol treatment. Hydrogen peroxide (H₂O₂) levels were significantly elevated under drought stress, reaching 3.48-fold and 8.00-fold increases in shoots and roots, respectively. Si application substantially reduced H₂O₂ accumulation to 1.95-fold and 3.81-fold in shoots and roots. Enzyme activity analysis revealed that ascorbate peroxidase (APX) remained relatively stable across treatments, while catalase (CAT) showed a sparing effect under Si application. Peroxidase (POD) activity remained elevated in Si-treated plants under stress, indicating maintained antioxidant defense capacity. These results demonstrate that Si mitigates drought-induced oxidative stress not only through enzymatic regulation but primarily by reducing primary ROS generation, thereby enhancing plant stress tolerance and growth performance under water-deficit conditions.

Abstract
Introduction
Materials and Methods
    1. Plant growth conditions and silicon application
    2. Osmotic stress treatment
    3. Determination of H2O2 levels
    4. Enzyme activity assays
    5. Native poly-acrylamide gel electrophoresis (PAGE)
    6. Statistical analyses
Results and Discussion
    1. Growth and stress responses of sorghum seedlingsto silicon under osmotic stress conditions
    2. Effects of silicon on antioxidant defense enzymesin osmotic-stressed sorghum seedlings
Acknowledgments
References

• Yun Hee Kim(Professor, Department of Biology Education, IALS, Gyeongsang National University, Jinju, 52828, Korea) Corresponding author