Mechanisms of salt tolerance in tritipyrum, a promising achievement of breeding programs against the deleterious effects of salinity stress, have not been fully explored. Therefore, we conducted a greenhouse experiment with four tritipyrum lines and one wheat cultivar under four salinity levels (0, 60, 120 and 180 mM NaCl), in hydroponic condition. Sampling for physiological traits was conducted in 48 hours, one week and one month after exposure to salinity treatment. The results showed that tritipyrum had more chlorophyll pigments and carotenoid than wheat. Furthermore, concentration changes of proline and carbohydrate was more prominent in tritipyrum than in wheat; superoxide dismutase and catalase as well as peroxidase and ascorbate peroxidase activity were lower in Az/b and (Ka/b)*(Cr/b), F6 than in Cr/b and wheat; lower malondialdehyde in Az/b and (Ka/b)*(Cr/b),F6 indicated higher salinity tolerance of these hybrids compared with wheat and Cr/b; it was also found that different genotypes used various defense mechanisms to adapt themselves to salinity. Other defense mechanisms such as developed photosynthetic machinery, better activity of non-enzymatic antioxidant systems and higher accumulation of compatible solutes can be more effective than antioxidant enzymes in higher salt tolerance of tritipyrum lines. Our results indicate that non-enzymatic defense systems are more important than enzymatic ones in tolerating salinity stress in tritipyrum lines. Furthermore, in comparison with wheat, higher salinity tolerance of tritipyrum lines, especially Az/b, can make them suitable for the improvement of salinity tolerance of common wheat by breeding programs.

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