Salix viminalis L. - A highly effective plant in phytoextraction of elements.

The aim of the study was to compare specimens of Salix viminalis L. able to grow in polluted mining sludge (A1) with specimens of the same willow clone growing in two unpolluted areas (A2 and A3). Plants from the polluted area were characterized by the highest accumulation of the majority of elements in their organs with a clear limitation of their uptake to roots and effective translocation to aboveground organs. Willows from the unpolluted areas were characterized by significantly higher biomass than the treated plants, as shown in the content of cellulose/holocellulose. The different chemical characteristics of the substrates influenced tree physiology, including the organic acids and phenolic compounds profile and/or content. The total content of organic acids in lateral roots was higher for S. viminalis L. grown in unpolluted areas, while for leaves the opposite situation was observed. However, their creation was significantly correlated with the content of the majority of elements in the organs of S. viminalis L. Enhanced synthesis of phenolic compounds in roots (besides quercetin) and in leaves (besides myricetin and quercetin) was confirmed in the polluted area, and correlated with metal content in plant organs. Resilient plants characterized not only by their survivability but also by their effective phytoextraction of toxic metals, have great potential for widespread practical application on highly polluted mining sludge and for reducing the associated threat to human health. The obtained results suggest that further investigation of these plants is necessary to determine the mechanism(s) responsible for their high survivability.