The effects of cadmium and zinc interactions on the accumulation and tissue distribution of cadmium and zinc in tomato (Lycopersicon esculentumMill.)

A pot experiment was conducted to investigate the effects of cadmium and zinc interactions on the accumulation and tissue distribution of cadmium and zinc in tomato (Lycopersicon esculentum Mill.). The results obtained in this study reveal that treatment of soil with Cd, Zn, or Cd-Zn did not improve plant growth as compared to control. The levels of concentrations of Cd and Zn in leaves, shoots and roots were determined. The highest concentration of Cd was 135.0 mg kg−1 d.w. in the leaves, 57.0 mg kg−1 d.w. in the shoots, and 210.0 mg kg−1 d.w. in the roots; Zn concentration ranged from 186.0–776.0 mg kg−1d.w. in leaves, 126.7–700.0 mg kg−1 d.w. in shoots, and 320.0–2015.0 mg kg−1 d.w. in roots of tomato plant. Significant inhibitory effects of Zn on Cd accumulation in all organs of tomato plant occurred only at toxic levels (100 and 1000 mg kg−1 soil), but the reduction in Cd concentration did not improve shoot and root biomass suggesting that Zn concentration became the dominant factor affecting plant growth. An examination of Cd-Zn interactions and their transfer to soil-plant system indicate their synergistic effect. Increasing Cd and Zn concentrations in soil result in an increase in the accumulation of Cd or Zn in the plant tissues.