Physiological responses of sesame seedlings to polyethyleneglycol 6000

Water stress tolerance is seen in almost all plant species or cultivars but its extent varies from species to species or cultivars to cultivars. Sesame (Sesamum indicum L.) is an important oilseed crop. The aim of the present investigation was to study the oxidative effects and antioxidant responses in two sesame cultivars (cvs Darab 14 and Yekta) subjected to different levels of poltethylene glycol (PEG 6000). PEG treatments included osmotic potential equal to 0, -0.3, -0.6 and -0.9 MPa and resulted in decrease of seeds germination, seedlings length, fresh and dry masses, relative water content, protein content but increase in contents of hydrogen peroxide, malondialdehyde, proline with increasing of osmotic potential. The activities of antioxidant enzymes such as superoxide dismutase, peroxidase, catalase and ascorbate peroxidase of sesame seedlings changed with the increase of water deficit. According to present study seedlings of cv. Yekta is more tolerant to water deficit than cv. Darab 14.