Nutrient management of plants is the most practical and easiest way of combating salt stress. The effect of silicon (Si) nutrition on salt stress symptoms was investigated in hydroponically grown rice seedlings. Seeds from Khazar (salt sensitive) and Zayandehrood (salt tolerant) cultivars of rice were exposed to 0 and 100 mM NaCl in the absence and presence of silicon (3 mM) using sodium silicate. Plant growth parameters, sodium (Na+) and potassium (K+) concentrations, Si accumulation, chlorophyll content and efficiency of PSII (Fv/Fm) were determined in 25 days old seedlings exposed to salinity for 96 h. The results showed that salt stress generally inhibited seedling growth and reduced photosynthesis efficiency. However, the addition of Si significantly decreased shoot Na+ concentration, but increased Si uptake. Additionally, in salinized plants, the addition of Si increased Fv/Fm in Khazar cultivar. It could be concluded that Na+ concentration, Si accumulation and Fv/ Fm ratio play key role in salinity stress tolerance. Application of Si, however, alleviated to some extent detrimental effects of salinity stress by improving growth and physiological performance of both cultivars under saline conditions.
