Abstract
Jasmonic acid (JA) critically participates in modulating plant responses to salt stress. Here, the protective role of JA against dilute seawater stress was investigated for Hassawi okra seedlings in pot experiments under controlled growth conditions. Seeds were soaked in 50 mu M JA. The seedlings were irrigated with different dilutions of seawater (0-40 %) for 3 weeks. Okra seedlings pretreated with JA tolerated brackish water up to the level of 10 %, and survived up to 40 %, while they exhibited damage and finally death if untreated. On the other hand, the level of 5 % seawater favorably affected the growth parameters compared to the fresh water control. The beneficial effect of JA was manifested by higher biomass, photosynthetic pigment and osmoprotectant levels, and decreased general stress markers such as ion leakage and lipid peroxidation. In addition, mineral composition was altered and the activity of some antioxidant enzymes improved. In conclusion, our results indicate that JA affects plant acclimation to sublethal salinity stress by brackish water. Since seed germination and seedling establishment are critical steps in plant growth, it is recommended to consider priming with JA as measure to ameliorate the detrimental effects of seawater stress and to improve Hassawi okra seedlings tolerance when irrigating with brackish water.