evidence for differential lipid peroxidation and antioxidant enzyme activities in sesamum indicum l. genotypes under nacl salinity

as sesame is a somewhat neglected crop, information concerning its response to salinity is lacking. the effects of nacl stress were studied on seven genotypes of sesamum indicum l. the 6-weeks-old sesame seedlings were treated with different nacl concentrations (0, 30, and 60 mm). the nacl caused significant decreases in fresh and dry mass of all genotypes; however responses of genotypes to the salt were significantly different. based on the data obtained for fresh and dry mass accumulation, the genotypes were divided into two groups: i.e. salt-tolerant (ardestan, varamin, and darab) and salt-sensitive (naz-takshakheh, naz-chandshakheh, yekta and oltan). lipid peroxidation was recorded to be the lowest in cv. ‘varamin’, ‘darab’, and ‘ardestan’ (tolerant group), whereas it was recorded to be maximum in genotypes ‘naz-takshakhe’, ‘naz-chandshakhe’, ‘oltan’ and ‘yekta’ (sensitive group) in the 60 mm nacl treatment. in both 30 and 60 mm nacl treatments, the activities of superoxide dismutase (sod), catalase (cat), ascorbate peroxidase (apx) and glutathione reductase (gr) were found to be higher in the tolerant group, compared to the sensitive group of genotypes. the accumulation of proline in the sesame leaves under saline conditions was higher in tolerant group, compared to the sensitive genotypes. it seems that in the salt-tolerant genotypes of sesame, increases in antioxidant enzymes activities and proline accumulation, along with a lower lipid peroxidation at cellular membranes, led to a higher level of tolerance to the salt.