Physiological Mechanisms Underlying Seed Dormancy-Breaking Treatments in Finger Millet [Eleusine coracana (L.) Gaertn.]

Abstract Seed dormancy is a major problem for rapid and uniform germination in finger millet (Eleusine coracana L. Gaertn.) resulting in poor crop establishment. Breaking seed dormancy before sowing necessitates for uniformity in field emergence and better plant stand. The present study investigated for the hormonal, biochemical, antioxidant, and metabolomic mechanisms that take place during different dormancy-breaking treatments of freshly harvested seeds. Among the treatments, 2% thiourea was the most effective, significantly improving seed germination and seedling vigour, followed by 2 mL/L ethrel. Dormancy release was associated with reduced abscisic acid (ABA) and indole-3-acetic acid (IAA) levels in seeds and increased gibberellic acid (GA) and indole-3-butyric acid (IBA), indicating a favourable hormonal balance for germination. Thiourea also enhanced α-amylase activity, total soluble sugars, and soluble proteins while reducing phenol, flavonoid, and tannin contents, reflecting improved reserve mobilization and reduced germination inhibitors. Increased activities of superoxide dismutase, catalase, and peroxidase further indicated an enhanced antioxidant defense system during dormancy release. GC–MS analysis revealed metabolite reprogramming, particularly under thiourea treatment, characterized by fatty acid remodelling, the disappearance of several metabolites associated with dormant seeds, and the exclusive detection of γ-tocopherol, suggesting enhanced lipid mobilization and antioxidant protection. Overall, the results demonstrate that thiourea effectively promotes dormancy release in finger millet through coordinated hormonal regulation, reserve mobilization, antioxidant defense, and metabolic reprogramming, providing a physiological and biochemical basis for improving seed germination and crop establishment.