In order to investigate the effect of salinity stress and amount of potassium on root and shoot biomass accumulation of saffron a greenhouse study was carried out in 2008-2009 at Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. The experimental design was factorial of salinity and potassium based on completely randomised block with three replications. Treatments included 4 levels of NaCl (0, 30, 60 and 90 mMol) and 3 levels of potassium (50, 100 and 150 % of Hoagland solution base). Results indicated that salinity imposed a significant effect on different growth characteristics, leaf dry weight, Number of leaf, root dry weight, root volum, root density and physiological caracteristics of saffron (P<0.01) and potassium significantly controlled the negative effects of NaCl on length and number of roots as well as fresh weight and number of leaves per plant. Potassium and NaCl interactions were also significant. At different levels of NaCl adding K to the root medium caused an increasing in root numbers per plant. But this trend was observed up to 60 mMol of NaCl and at 90 mMol NaCl, Potassium showed no modifying effects. Relative water content and electrolyte leakage were drastically decreased by increasing NaCl salinity. There were reduces at 90 mMol compared to the control respectively. The best growth parameter and root to shoot ratio was found with 30 mMol of Nacl. It seems that the application of extra potassium in the rhizosphere of saffron (up to 150%) can reduce the damaging effects of NaCl up to 60 mMol of NaCl in soil solution.

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