impact of cr (vi), cd and pb contamination on nutrient composition of one-year old populus ssp. seedlings

heavy metals are aggressive environmental pollutants. they are easily taken up by plants and they are strong stress factors for plant metabolisms. heavy metals influence includes also disturbances in plant mineral nutrition by competition with other nutrients. the specific objective of this research work was to study whether elevated cr (vi), cd and pb contamination caused an unbalanced nutritional status of leaves and stems/shoots in two poplar species (p. nigra l. and p. alba l.). the experiment was carried out on a pot culture of poplars, growing in an enriched heavy metal soil. the results indicated that heavy metal enrichments reduced the concentration of all foliar and stem/shoot nutrients (p≤0.05). p.nigra l. in comparison with p. alba l. was more sensitive to cd and cr (vi) contamination. the highest and the lowest negative effects on nutrient uptake were belonging to cd and pb respectively. cd contamination at 150 mg kg-1 level lead to 65% reduction in foliar concentration of k in p. nigra l. in presence of 150 mg kg-1 cd, 78% reduction was observed in p. nigra l. p uptake compare to control. the knowledge about regulatory mechanisms in plant mineral nutrition may help us to solve the problem of plant detoxification during heavy metal stress. however the mechanisms of heavy metal interactions are very complex and still only fragmentarily known.