Tissue analysis of fluecured tobacco plants with different degrees of calcium deficiency sampled from the tobacco production base located in Southwest China show that the symptom of calcium deficiency on tobacco plants was mitigated with increasing Ca concentration in the leaves,but aggravated with increasing SO₄^2- and PO₄^3- concentrations in the leaves.Results of the hydroponic experiment indicated that high PO₄^3- concentration in the solution could induce symptom of calcium deficiency on tobacco plants.The greater the PO₄^3- concentration in the solution,the earlier the occurrence of the symptom,and the more serious the symptom.These findings revealed that serious calcium deficiency of tobacco plants in the production base resulted from application of the commercial organic manure containing high concentrations of SO₄^2- and PO₄^3-,which reduced solubility of Ca in the rhizosphere,thus hindering uptake and transport of Ca²⁺ by the plants.