Effects of 24-Epibrassinolide on Growth and Some Antioxidant Enzymes of Cotton (Gossypium hirsutum L.) Cultivars under NaCl Stress
The present study was conducted to investigate the anti-stress effects of 24-Epibrassinolide (EBL), an active brassinosteroid, in cotton cultivars against the NaCl stress. Nine cotton cultivars were tested for their germination responses to varying NaCl concentrations. According to germination test result, two tolerant (Nazilli 84-S and Carmen) and two sensitive (Sahin 2000 and Beyaz Altin 119) cultivars were selected for the experiments. Seeds of four cultivars were soaked in 3 μM EBL for 24 h and seedlings were irrigated with solution containing the various concentration of NaCl (0, 50, 100 and 150 mM). Germination, growth (fresh weight, dry weight, shoot and root length) and pigment content (chlorophyll a, chlorophyll b and carotenoid) reduced under salinity stress whereas the treatment with EBL alleviated the inhibitory effects of salt stress. Under high NaCl stress, superoxide dismutase (SOD), guaiacol peroxidase (GPX) and proline contents increased in 21-old-days seedlings; however EBL further increased the activity of antioxidant enzymes and proline content in cotton cultivars.