Interaction between cadmium and iron. Accumulation and distribution of metals and changes in growth parameters of Phaseolus vulgaris L. seedlings

The interaction between cadmium, one of the most toxic heavy metals, and iron, an essential plant nutritional element, was investigated in Phaseolus vulgaris L. (cv. Słowianka) seedlings. The interaction was externally induced by changing the content of both metals in the nutrient medium. Under iron deficiency conditions (0 and 0.5 of normal dose of this element), the toxic effects of cadmium on plant growth parameters, like fresh and dry weight accumulation, primary leaves area, etc., were generally much more pronounced than under normal iron supply. At normal and excess iron supply (1, 2 and 4 doses) cadmium diminished iron accumulation in roots and primary leaves, but on the other hand excess iron decreased cadmium level, preventing plants from extreme toxicity of very high cadmium concentrations in the growth environment. It is to be noted that iron is classified also as a heavy metal, and its excess may become toxic, e.g. decreasing root dry weight or diminishing leaf area, especially at the highest dose. The detoxication role of iron against cadmium, and possibly other toxic metals is, however, limited to concentrations of this element in the nutrient solution which themselves are not toxic for the organism