ABSTRACT
Flax (Linum usitatissimum) is an important oilseed and medicinal plant that numerous breeding lines andcultivars have been produced by plant breeders up to now. The present study was conducted to evaluate thebiochemical factors changes affected by NaCl oxidative stress in different genotypes of flax. For this purpose,an experiment was conducted as a factorial arrangement based on a completely randomized design with threereplications in greenhouse conditions. The experimental factors included three genotypes (Tabare, Golchin,and 375Ha) as the first experimental factor and salinity stress (120 mM NaCl) time course at three levels (0,24, and 48 hours after salinity treatment) as the second factor. The measured biochemical factors in the leafwere catalase, guaiacol peroxidase, malondialdehyde, hydrogen peroxide, proline, and superoxide dismutase(SOD). The results showed that salinity stress had a significant effect on the content of measured biochemicalparameters. The levels of catalase, guaiacol peroxidase, hydrogen peroxide, and proline were statisticallysignificant in the tolerant flax genotypes. Furthermore, the interaction of genotype and time after applyingstress had a significant effect on the catalase, hydrogen peroxide, and proline content. The amount of catalaseand proline in the 24 hours after stress was more than the 48 hours, indicating the key role of these factors at thebeginning of the stress. On the other hand, the amount of guaiacol peroxidase and SOD increased significantlyin 48 hours after stress. Generally, the content of the antioxidant factor increased significantly under salinitystress, especially in 375Ha tolerant genotype. This indicates the importance of these enzymes in salt stresstolerance in order to more accurately evaluate the genotypes sensitive and tolerant to the flaxseed in the seedlingstage. These results confirmed the slat tolerance of 375Ha genotype in the seedling stress and therefore can bea promising line for regions with slat stress conditions.