Physiological mechanism of H₂O₂ treatment to repair aged Cyperus esculentus

Cyperus esculentus are a new kind of multi-purpose oil crop; however, the tubers used for reproduction are hard to store, and seed vigor has been found to rapidly decrease during storage. In this study, naturally aging round grain C. esculentus were used to explore the remediation effects of different concentrations of H₂O₂ (0, 0.01%, 0.1%, 1%, 3%, 5%). The results showed that H₂O₂ treatment is able to effectively repair aged C. esculentus, improve tuber vigor and promote germination. We found that the repairing effect was best at a H₂O₂ concentration of 1%, and the germination rate, germination potential and germination index all increased significantly (P < 0.05); however, the average germination days did not change significantly ( P > 0.05). In addition, we found that the agronomic traits of seedlings increased initially and then decreased with an increasing H ₂O₂ concentration. Physicochemical analysis showed that after H₂O₂ treatment, the soluble sugar and soluble protein content, along with the catalase (CAT) and superoxide dismutase (SOD) activities, and gibberellins (GA₃) and abscisic acid (ABA) content, increased initially and then decreased. In contrast, the malondialdehyde (MDA) content decreased significantly (P < 0.05), and the amylase content initially decreased and then increased. Grey correlation analysis found that GA ₃ was the most important factor affecting the repairing effect of H₂O₂ in aged tiger nuts. In conclusion, our results revealed that H₂O₂ repaired tiger nut aged tubers by regulating the antioxidant enzyme and amylase activity, MDA content, osmotic regulatory substance content and endogenous hormone level, and promoted tuber germination and seedling growth.