Responses of 11-bread wheat (Triticum aestivum L.) and 9 durum wheat (Triticum turgidum L.) genotypes to salinity stress was evaluated using in the greenhouse condition in 2003. (Factorial experiment with completely randomized design (three replications)). Salinity levels were 0.72 (control), 8.1 , and 11.5 dSm-1. Salinization began when the seedling were at the two leaf stage. After 20 days exposure to salt, leaves were harvested for measurement of K+ , Na+ and proline accumulation. The second level of salinity, (8.1 dSm-1), significantly increased Na+ concentration, while K+ concentration and K+ / Na+ decreased in bread and durum wheat genotypes. These variable were significantly (p<0.001) different at both species. At EC= 11.5 dSm-1, there was no reduction in K+ concentration compared to 8.1 dSm-1. The results showed that Omid and Marvdasht were most tolerant and line-128 was the most sensitive one among bread wheat genotypes. In durum wheats, line-168 was the most tolerant and Yavares was the most sensitive. As the duration of salinity stress increased, proline concentration increased in wheat genotypes. At salinity stresses, the highest proline concentration was observed in non-tolerant genotypes, and the least concentration was in tolerant genotypes. Therefore, Prolline level may not be introduced as a suitable salt tolerance index in wheat. Stress tolerance index (STI) revealed that Omid and line-84 among bread wheat and durum wheat genotypes based on biological yield, were respectivelysuitable for stress and non-stress conditions.Omid and line-68 had lowest tolerance index (TOL).
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