Gibberellic Acid Amended Antioxidant Enzyme and Osmotic Regulation to Improve Salt Tolerance of Okra at Early Growth Stage

摘要

Seed germination and emergence are most staple stages for crops establishment. However, these stages are severely inhibited under salinity stress. External application of regulating substances might be an effective method to alleviate the suppression effects. But the associated physiological mechanism is still in controversial. Therefore, this research evaluated the amendment effects of gibberellic acid (GA3) on plant growth, antioxidant enzymes and osmotic regulation of okra (Abelmoschus esculentus L.) under salinity stress. The results showed that increasing NaCl level from 0 to 120 mM, growth related parameters like plant height, leaf area, dry weight of root, stem and leaf were significantly decreased. Enzyme activities of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) were slightly or significantly increased at 60 mM NaCl level, but significantly reduced at the 120 mM NaCl level. The osmotic regulation substances including soluble proteins (SP) and proline (Pro), significantly increased under both 60 and 120 mM NaCl levels. Compared with 300 μM GA3, presoaking seeds with 150 μM GA3 had the best effects on increasing growth-related parameters. The activity of POD and SOD, together with Pro and SP increased prominently at 150 μM GA3. These results suggest that using optimum concentration of GA3 for priming seeds is an alternative way to improve early seedling growth of okra under saline conditions.