In order to understand the physiological traits important in conferring salt tolerance in three barley genotypes, this study was performed under field conditions with three water salinity levels (2, 10, and 18 dS m-1). High salinity decreased net photosynthetic rate, transpiration rate, and stomatal conductance, K+ concentration, K+:Na+ ratio, and grain yield, but increased electrolyte leakage and Na+ content. Under 10 and 18 dS m-1 salinity, Khatam (salt-tolerant) had the maximum stomatal conductance, K+, K+:Na+ ratio, and the grain yield, and a minimum Na+ content and electrolyte leakage, whereas Morocco (salt-sensitive) had the lowest net photosynthetic rate, stomatal conductance, K+ content, K+:Na+ ratio, and grain yield, and the highest Na+ content and electrolyte leakage. This study showed that tolerant genotypes of barley may avoid Na+ accumulation in aboveground parts, facilitating a higher photosynthetic rate and higher grain yield., M. Mahlooji, R. Seyed Sharifi, J. Razmjoo, M. R. Sabzalian, M. Sedghi., and Obsahuje bibliografii