Aims Euphrates poplar (Populus euphratica Oliv.) is a woody species, which is naturally distributed in desert areas of some parts Asia and Africa. This research was conducted to evaluate the physiological response to salinity stress in 12 ecotypes in Iran. Materials & Methods This study was conducted to evaluate the physiological response to different levels of salinity (75, 150, 225, and 300 mM NaCl) with control and to assess the response physiologic traits such as RWC, EL, MDA, Proline, GB, TSS, plant pigments, SOD, CAT, and GPX. Findings The analysis of variance showed that there was a significant difference between treatments all traits. Comparing means of ecotypes showed that Hamidieh was the highest group and Mahneshan and Marand were in the lowest group. Comparing means of treatments showed that 75 mM was the highest group in terms of performance. The 75 mM was the highest group in terms of SOD activity; in contrast, 300 mM and control were in the lowest group Conclusion The result represents that Populus euphratica is a moderate halophyte, which could be suggested to reclamation of saline lands with high water table. This uses multiple mechanisms to overcome salinity stress and there is not a clear path to overcome salinity in this species. Cluster analysis divided the examined ecotypes into five groups based on total traits. The ecotypes grouping was not based on geographical distance, rather it was based on the conditions of the original habitat especially soil salinity
