Ameliorating effects of exogenously applied ascorbic acid on seawater irrigation - induced oxidative stress in Roselle seedlings

The objective of this work was to evaluate the ameliorating effects of ascorbic acid (AsA) to stress imposed by seawater irrigation on roselle (Hibiscus sabdariffa L. with red sepals variety) seedlings. Irrigation of seedlings with seawater caused a reduction of growth and water content. On the other hand, ion leakage, lipid peroxidation, activities of some antioxidant enzymes, endogenous AsA, total free amino acids and proline were enhanced. Exogenously application of 200 ppm AsA through seeds presoaking ameliorating the inhibitory effects of seawater stress, which were accompanied by increase of soluble carbohydrates and proteins and antioxidant enzymes. However, seawater stress induced accumulation of proline, total free amino acids, ion leakage and lipid peroxidation was lesser in ASA treated as compared with AsA untreated seedlings. The results suggested that, application of AsA may help in improving the tolerance of Hibiscus sabdariffa L. seedlings to seawater stress by neutralizing the excessive reactive oxygen species (ROS).