LONG TERM SALINITY STRESS IN RELATION TO LIPID PEROXIDATION, SUPER OXIDE DISMUTASE ACTIVITY AND PROLINE CONTENT OF SALT-SENSITIVE AND SALT-TOLERANT WHEAT CULTIVARS

Salinity is a widespread root medium problem limiting productivity of cereal crops worldwide. The ability of plants to tolerate salt is determined by multiple biochemical pathways that facilitate retention and/or acquisition of water, protect chloroplast functions, and maintain ion homeostasis. Therefore, the ability of salt-sensitive ('Tajan') and salt-tolerant cultivar ('Bam') of Triticum aestivum L. to adapt to a saline environment were evaluated in a set of greenhouse experiments under salt stress during three growth stages (tillering, 50% anthesis, and 10 d after anthesis). Plants were irrigated by different saline waters with electrical conductivities of 1.3, 6, 8, 10, and 12 dS m(-1), which were obtained by adding NaCl:CaCl2 in 10:1 molar ratio to fresh water. Differences in growth parameters, lipid peroxidation, superoxide dismutase (SOD) activity, and proline accumulation were tested in order to put forward the relative tolerance or sensitivity of cultivars. Results indicated that both parameters differ according to the cultivar's ability in coping oxidative stress caused by salinity. We observed a greater decline in the growth parameters and grain yield under salt stress in 'Tajan' than in 'Bam'. Malondialdehyde content was also higher in 'Tajan'. The improved performance of the 'Bam' under high salinity was accompanied by an increase in SOD (EC 1.15.1.1) activity and proline content at all growth stages. Growth parameters, lipid peroxidation and proline accumulation results are also in good correlation with supporting this cultivar is being relatively tolerant.