Abstract: The tomato seedlings had different responses to iso-osmotic Ca(NO₃)₂ and NaCl solution. The reduction of plant growth under 28 and 56 mmol/ L Ca(NO₃)₂ solution was greatly smaller than those under iso2osmotic NaCl solution , but under 84 mmol/ L Ca(NO₃)₂ solution the inhibition was the same as that under the iso2osmotic NaCl solution. The plant growth was inhibited by high concentration of Ca(NO₃)₂ mainly through osmotic stress. Ion stress is the main reason of growth inhibition under NaCl : including destroy of membrane structure and reduction of potassium uptake.

Key words: Tomato, Salt stress, Salt toxicity, Ca (NO3) 2, NaCl, Salt response