In order to evaluate salinity tolerance of six bread wheat varieties, an experiment was conducted during 2000-02 crop seasons in Roudasht Salinity Research Station, Esfahan. Effects of three levels of irrigation water salinities (four, eight and 12 dS m-1) were studied on six bread wheat cultivars including Pishtaz, Shiraz, Mahdavi, Marvdasht, Kavir and Roshan. Increase in salinity level of irrigation water caused significant decrease in grain yield, number of spikes per m 2 , days to

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... cal maturity, plant height and grain filling period. Among the varieties, Roshan and Shiraz had the minimum reduction percentage in grain yield in 12 dS m-1 compared to 4 dS m-1. In 12 dS m-1 , Roshan and Shiraz produced 3987 and 3607 kg ha-1 grain yield, respectively and had the highest grain yield values among the varieties. Roshan also had the highest amounts of MP, GMP and STI (4257, 4248 and 1.20, respectively) and the lowest amounts of Tol and SSI (539 and 0.66, respectively), thus was the most tolerant cultivar to salinity among the studied cultivars. Based on the tolerance and susceptibility indices, Marvdasht was the most susceptible cultivar to salinity.