Influence of Ca,K Concentration and pH Value in Solution on Cd Toxicity to Tobacco in Solution Culture

The acute toxicity of cadmium(Cd) to tobacco cultivar(Nicotiana tabacum L.) as affected by calcium(Ca),potassium(K) concentrations and pH values was assessed by using Log-logistic distribution model in solution culture.The results showed that the 10% and half inhibitory concentration(EC10,EC50) of Cd toxicity increased with the increment of pH values in solution as determined by tobacco root elongation,which indicated that the toxicity of Cd to tobacco decreased with the increasing pH values in solution,a significantly positive correlation was observed between the ECs(s=10,50) and pH values in solution.The half inhibitory concentration(EC50) of Cd toxicity to tobacco increased 6.73 times greater when the pH value increased from 4.52 to 8.10 in solution.The addition of Ca ion in solution could markedly decrease the Cd-toxicity to tobacco cultivar as assessed by EC10 and EC50 with an optimum maximum concentration of 128.0 mg/L.In terms of K ion,low concentration of K ion addition(64.0 mg/L) could marginally decrease the toxicity of Cd to tobacco cultivar in solution as assessed by EC10,however,it could significantly decrease the Cd-toxicity to tobacco cultivar with greater concentration addition more than 64.0 mg/L in solution.Increasing pH and Ca,K concentration in culture matrix could significantly decrease toxicity of Cd to tobacco cultivars in Cd-polluted matrix.