Growth and Metal Uptake by Plants Grown in Mono- and Dual Culture in Metal-contaminated Soils

Plants are able to affect the mobility of heavy metals in the rhizosphere due to root exudates and other mechanisms resulting in a change in their phytoextraction ability. We tested separate (monoculture) and intercropping (dual culture) systems of hyperaccumulator Thlaspi caerulescens and accumulator tree Salix dasyclados in two soils with different levels of contamination. Intercropping did not significantly affect accumulation and removal of Cd, Pb, and Zn in moderately contaminated soil. Separately cropped S. dasyclados continuously died due to phytotoxicity of the highly contaminated soil. We indicated an important positive effect of intercropping in this soil. Intensive uptake of heavy metals by Thlaspi roots decreased relatively toxic concentrations in soil and improved the growth of S. dasyclados. The maximum limit of the phytoextraction potential of T. caerulescens was not reached at the extremely contaminated soil but the efficiency of the intercropping at the extremely contaminated soil still remains limited and alternative remediation techniques can be considered at this particular contaminated site.