en Effects of NaCl on some physiological and biochemical responses in two cultivars of L. usitatissimum تنش شوري Salt Stress پژوهشي Research <strong><em>Linum usitatissimum</em></strong><strong>&nbsp;L. is one of the economically important oilseed crops and salt stress is one of the major environmental challenges affecting several physiological processes in plants. The present investigation was carried out to study the effects of NaCl on some physiological and biochemical responses in&nbsp;</strong><strong>two</strong><strong>&nbsp;cultivars of&nbsp;<em>L. usitatissimum</em>.&nbsp;</strong><strong>Twenty-one-day-old-plants were exposed to salt stress (0 and 150 mM) for 21 days.&nbsp;</strong><strong>Results showed that salinity increased proline, phenol and flavonoid contents and total antioxidant capacity (based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and&nbsp;</strong><strong>Ferric reducing antioxidant power (</strong><strong>FRAP) assays) in flax cultivars. Levels of oxidative stress parameters, such as Malondialdehyde (MDA) and other aldehydes, content of Na⁺&nbsp;and Cl^-&nbsp;and peroxidase (POD) enzyme activity were increased in NaCl-treated plants. The content of soluble protein was elevated and decreased in TN-97-28 and TN-97-106 cultivars, respectively. On the other hand, other antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APOX) were decreased and increased in TN-97-28 and TN-97-106 cultivars, respectively. It might be concluded that various cultivars have different mechanisms to diminish negative impacts of salinity stress.</strong> <strong><em>Linum usitatissimum</em></strong><strong> L. is one of the economically important oilseed crops and salt stress is one of the major environmental challenges affecting several physiological processes in plants. The present investigation was carried out to study the effects of NaCl on some physiological and biochemical responses in </strong><strong>two</strong><strong> cultivars of <em>L. usitatissimum</em>. </strong><strong>Twenty-one-day-old-plants were exposed to salt stress (0 and 150 mM) for 21 days. </strong><strong>Results showed that salinity increased proline, phenol and flavonoid contents and total antioxidant capacity (based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and </strong><strong>Ferric reducing antioxidant power (</strong><strong>FRAP) assays) in flax cultivars. Levels of oxidative stress parameters, such as Malondialdehyde (MDA) and other aldehydes, content of Na⁺ and Cl^- and peroxidase (POD) enzyme activity were increased in NaCl-treated plants. The content of soluble protein was elevated and decreased in TN-97-28 and TN-97-106 cultivars, respectively. On the other hand, other antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APOX) were decreased and increased in TN-97-28 and TN-97-106 cultivars, respectively. It might be concluded that various cultivars have different mechanisms to diminish negative impacts of salinity stress.</strong> Antioxidant enzymes, Flax, Proline, Protein, Lipid, NaCl 25 34 http://jispp.iut.ac.ir/browse.php?a_code=A-10-1121-1&slc_lang=en&sid=1 Leila Amraee l.amraei@urmia.ac.ir@gmail.com Yes Department of Biology, Faculty of Sciences, Urmia University, Urmia, Iran Department of Biology, Faculty of Sciences, Urmia University, Urmia, Iran دانشگاه ارومیه Rahmani No Institute of Biotechnology, Urmia University, Urmia, Iran دانشگاه ارومیه Babak Abdollahi b.abdollahi@urmia.ac.ir No Department of Plant Breeding and Biotechnology, Faculty of Agriculture, Urmia University, Urmia, Iran دانشگاه ارومیه