Toxicity of nickel and cadmium in spruce seedlings: Effect of separated and combined treatments on peroxidase and superoxide-dismutase activity

separately and simultaneously. The kinetics of metal assimilation and total accumulated quantity depended on the type of treatment. Following metal exposure, an increase in peroxidase activity in the seedlings treated with Cd and Ni/Cd, and in superoxide-dismutase activity during Ni/Cd treatment was observed. A parallel change of peroxidase isoenzyme pattern occurred. There was a good correlation between accumulated metals in needles and enzyme activities. The effect of Cd on the measured parameters was shown to be stronger comparing to the effect of Ni. The results obtained show that peroxidase and superoxide-dismutase activity and peroxidase isoenzyme pattern could be used to evaluate the capacity of one part of the defense system in spruce seedlings to withstand metal stress.