In most Bio-environmental standards, the allowable limit of heavy metals release in environment was determined for all compounds of a given element. However toxic effects and pollution potential of these elements is relatively dependent upon their kind and chemical composition. In this research, the effect of CdCl2 and Cd(N03)2 on the growth of tomato plants (Lycopersicum esculentum) was separately evaluated, as well as, the amount of uptake and accumulation of Cd by root and shoot parts of this plant in the presence of these salts.
The results showed that deleterious effect of Cd(N03)2 on the growth of plants was significantly greater than CdC12. Also, the uptake and accumulation of this element by plant organs in media that contain Cd(N03)2 was greater than in media containing CdC12.
It is concluded that in surveying the pollution effects of heavy metals, not only their quantity but also the kind and chemical composition must be considered. Because plants adaptation to some salts like nitrate cause easy entry of these compounds to biological circles and increases pollution.