The influence of single and multiple soil contamination of cadmium with lead and zinc on growth, chlorophyll contents, uptake and translocation of cadmium in tomato plants

A study was carried out on the influence of increasing levels of single and multiple soil contamination with Cd, Pb and Zn (5, 15, 25 or 50 mg Cd kg−1 soil; 125, 250, 500 or 1000 mg Pb and Zn kg−1 soil) on growth, chlorophyll and Cd content of tomato plants. At a level of Cd5Pb125Zn125, Pb2+ and Zn2+ have a protective effect and decrease the phytotoxic effect of Cd2+ on tomato plant. At higher levels, growth parameters (shoot weight, root weight and chlorophyll content) are reduced parallel to the enhancement of Cd concentration. At a level of Cd15Pb250Zn250, Pb2+ and Zn2+ alleviate the unfavorable effects in triple combinations. Above the level Cd15Pb250Zn250, Pb2+ and Zn2+ interact antagonistically with Cd2+. The reduction of tissue Cd content is not always accompanied by an alleviating effect of Cd phytotoxicity. The Cd-Zn combination decreases the tissue Cd content more effectively than Cd-Pb, but its phytotoxic effect is more pronounced. The Cd toxicity depends more on free Cd ions than on total tissue Cd content. The translocation of Cd from root to leaves is higher compared to its accumulation from root to shoot.