EFFECT OF APPLICATIONS OF DIFFERENT POTASSIUM (K+) DOSES ON ANTIOXIDANT ENZYME ACTIVITIES IN PEPPER PLANTS UNDER SALT STRESS

This study was carried out to determine the antioxidant enzyme activities in pepper (Capsicum annuum L. cv. Demre - long pepper) plants grown under salt stress and supplied different doses of potassium (K+). The study was conducted under controlled conditions in a 16/8 h light / dark photo period, at 25 degrees C and in a chamber with 70% humidity. After the seeds planted in pumice were germinated, seedlings with 2 true leaves were transferred into hydroponic culture containing the Hoagland nutrient solution. The K+ concentrations in the Hoagland solution were calculated as 146 mg L-1, and this level was used as a control. Other doses were set to be 20 mg L-1 lower and then 20 mg L-1 and 40 mg L-1 higher than the control dose (K1 = 126 mg L-1, K2 = 146 mg L-1, K3 = 166 mg L-1, K4 = 186 mg L-1). The salt stress level applied to the plants was induced by 100 mM sodium chloride (NaCl). Sampling for measurement and analysis was done on the 20th day of the salt application. The samples underwent the following determinations: Catalase (CAT), Ascorbate Peroxidase (APX) and Superoxide dismutase (SOD) relative to the total plant weight, and Antioxidative enzyme activities. The results indicate that K+ applications in the K3 = 166 mg L-1 and K4 = 186 mg L-1 doses reduced the impact of salt stress and the plants were less severely affected. Their antioxidant enzyme activities values in comparison to the control and other doses of K+ were quite low.