A sand culture experiment was conducted to answer the question whether or notexogenous KNO3 can alleviate adverse effects of salt stress in winter wheat bymonitoring plant growth, K+/Na+ accumulation and the activity of some antioxidantenzymes. Seeds of two wheat cultivars (CVs), DK961 (salt-tolerant) and JN17(salt-sensitive), were planted in sandboxes and controls germinated and raised withHoagland nutrient solution (6mM KNO3, no NaCl). Experimental seeds were exposedto seven modified Hoagland solutions containing increased levels of KNO3 (11, 16,21 mM) or 100mM NaCl in combination with the four KNO3 concentrations (6, 11, 16and 21 mM). Plants were harvested 30 d after imbibition, with controls approximately22 cm in height. Both CVs showed significant reduction in plant height, rootlength and dry weight of shoots and roots under KNO3 or NaCl stress. However, thecombination of increased KNO3 and NaCl alleviated symptoms of the individual saltstresses by improving growth of shoots and roots, reducing electrolyte leakage,malondialdehyde and soluble sugar contents and enhancing the activities ofantioxidant enzymes. The salt-tolerant cultivar accumulated more K+ in both shootsand roots compared with the higher Na+ accumulation typical for the salt-sensitivecultivar. Soluble sugar content and activities of antioxidant enzymes were found to be more stable in the salt-tolerant cultivar. Our findings suggest that the optimal K+/Na+ ratio of the nutrient solution should be 16:100 for both the salt-tolerant and thesalt-sensitive cultivar under the experimental conditions used, and that thealleviation of NaCl stress symptoms through simultaneously applied elevated KNO3was more effective in the salt-tolerant than in the salt-sensitive cultivar.& 2008 Elsevier GmbH. All rights reserved.