EFFECTS OF DIFFERENT DOSES OF EXOGENOUS GIBBERELLIC ACID ON TOTAL PLANT WEIGHT, LIPID PEROXIDATION, AND ANTIOXIDANT ENZYME ACTIVITIES OF EGGPLANT SEEDLING UNDER SALT STRESS

摘要

The present study investigated the effects of different doses of gibberellic acid (GA_3) on Aydin siyahi eggplant variety exposed to salt stress. The study was conducted to determine how applications affect plant development and metabolic activity. Eggplant seedlings were grown in a temperature- controlled hydroponic system in Hoagland nutrient solution. When they were 3 weeks old, they were exposed to salt stress (100 mM NaCl). Subsequently, they were treated with different doses of GA_3 (2.5, 5.0, 7.5, and 10 ppm). Leaves were harvested on the 15th day of the experiment. Fifteen days after the induction of salt stress, physiological (total plant weight) and biochemical (antioxidant enzyme activity, malondialdehyde [MDA] content, and chlorophyll content) changes were measured to determine the effect of the GA_3 treatments on plant growth and metabolic activity. In the NaCl plus high GA_3 treatment, the plant chlorosis level and degree of salt-induced damage decreased. In the NaCl plus high GA_3 (10 ppm treatment), plant development slowed due to salt-induced stress, but symptoms of stress, such as curling or chlorosis, were not detected in plant leaves. All doses the GA_3 treatments reduced antioxidant enzyme activities and MDA contents. In summary, the application of GA_3 to eggplant partially suppressed the adverse effects of salt stress on plant development and metabolic activities, and this effect was more apparent at a GA_3 dose of 10 ppm. Therefore, GA_3 may provide direct and indirect protection against salt stress.