SALINITY TOLERANCE COMPONENTS AND RESPONSE OF IRANIAN WHEAT CULTIVARS TO NaCl STRESS

Introduction and target: Salinity stress is a major constraint inhibiting yield of crops throughout the world. Salinity tolerance in crops can be categorized to three main mechanism including osmotic tolerance, ion exclusion and tissue tolerance. method: In this experiment, we try to quantification of these traits to increase salinity tolerance in future wheat genotypes. Selected cultivars for this aim named: Akbari, Sistan, Arg, Ofogh as salinity tolerant and Kohdasht and Morvarid as local cultivated wheat and finally Falat and Roshan as old and successful cultivars in last decades. The seeds planted in pots with sandy medium and irrigated with saline (150 mM NaCl) and nonsaline Modified Hoagland solutions. The growth rate reduction after salt application was used for calculation of osmotic tolerance. Na+ exclusion mechanism was quantified by measuring of the concentration of Na+ in leaves which exposed by salinity. Combination of Na+ content in salt stressed plants and measuring of salt induced leaf senescence was used to estimate tissue tolerance. Findings: Results showed that Ofogh and Roshan cultivars were best excluders than others. The strategy of osmotic tolerance considered as the best mechanism for all of experimental cultivars, and there were a little difference among them. Tissue tolerance was less effective in predicted total salinity tolerance and the cultivars of Morvarid, KohDasht and Falat were the best cultivars in this trait. Conclusion: It appears that cultivars with two tolerance mechanism either osmotic tolerance with Na+ exclusion (such as Ofogh and Roshan) or tissue tolerance with osmotic tolerance (such as Morvarid and KohDasht) have higher total salinity tolerance.