Seed treatment with H₂O₂ modifies net photosynthetic rate and antioxidant system in mung bean (Vigna radiata L. Wilczek) plants

Hydrogen peroxide (H₂O₂) in minute concentrations serves as a signaling molecule for processes involved in the growth and development of plants. The present study aimed to explore the role of seed treatment with H₂O₂ on growth biomarkers, photosynthetic traits, activities of carbonic anhydrase, and various antioxidant enzymes in 45-day-old plants of mung bean (Vigna radiata L. Wilczek) cv. SML-668 under non-stress conditions. The seeds were soaked in 0, 0.01, 0.1, or 0.5 mM H₂O₂ for 2, 4, or 8 h, and then inoculated with Rhizobium, sown in sandy loam soil, and allowed to grow for 45 days. The plants that developed from the H₂O₂-treated seeds demonstrated improved growth and photosynthetic attributes, enhanced activity of various antioxidant enzymes (e.g., catalase, peroxidase, and superoxide dismutase), and higher accumulation of proline than plants from non-treated seeds. The H₂O₂-triggered upregulation of antioxidant enzymes and proline (osmolyte) could have resulted in the observed improvement of growth and development. Out of the three concentrations of H₂O₂ tested, seed soaking with 0.1 mM for 4 h proved to be the best.