Interaction Effect of Cadmium and Potassium on the Antioxidant Activity and Nutrients Concentration of Tomato

The presence of cadmium in the soil is a major threat to plant growth and productivity. Plants often accumulate cadmium in their edible part, reducing the yield and quality of the product. In order to evaluate the effect of different concentrations of potassium (100, 200 and 300 mg L-1) under different levels of cadmium (0, 2 and 4 mg L-1) stress in tomatoes and potassium efficiency in reducing stress effects, a factorial experiment based on a completely randomized design was carried out with 3 replications. The results showed that with raising the cadmium concentration, malondialdehyde content, hydrogen peroxide content and guaiacol peroxidase activity were increased. The interaction effect of cadmium and potassium on the Fe concentration in the fruits and Zn concentrations in the leaves and fruits of tomatoes was not significant; however, the use of each of them alone had a significant effect; so, potassium consumption increased the concentrations of Fe, Zn and K in the fruits and decreased the malondialdehyde and hydrogen peroxide. The results of greenhouse experiments showed that the use of potassium nitrate fertilizer improved the efficiency of the plant phytoremediation in reducing the cadmium stress, although it is necessary to continue research in the field.