Hydrocharis dubia seeds maintain high seed vigor in ambient wet storage condition through scavenging hydrogen peroxide by antioxidant systems

To evaluate the mechanisms of seed vigor maintenance in an aquatic plant, Hydrocharis dubia, we studied the responses of germination ability, moisture content, H2O2 content, antioxidant enzyme activities, and antioxidant contents of the seeds under dry and wet storage conditions separately. Germination ability decreased significantly in dry environment, but was maintained at a high level in wet environment. Moisture content was significantly higher in wet treatment than in dry treatment. There was a significant positive relationship between germination ability and moisture content. The seeds in dry treatment accumulated significantly higher H2O2 than in wet treatment. There was a significant negative relationship between germination ability and H2O2 content. Superoxide dismutase activity in wet treatment was significantly higher than in dry treatment. Similar results were observed in guaiacol peroxidase, ascorbate peroxidase and dehydroascorbate reductase activities and proline content. No significant differences were found in ascorbic acid content. These results indicated that H. dubia seed vigor was associated with seed moisture and H2O2 content. The seeds in H. dubia maintained high seed vigor in wet environment through H2O2 scavenging by antioxidant systems. Based on our results, we suggest to store H. dubia seeds in wet condition.