Metal Hyperaccumulation in Cardaria draba (L.) Desv. (Brassicaceae) and Heavy Metal Effects on the Nematodes and a Weevil Associated with the Plant Roots in Sites near a Non-Ferrous Metal Smelter in Bulgaria

摘要

The heavy metal hyperaccumulation in Cardaria draba (L.) Desv. was studied in sites with different level of contamination with Pb, Cd, Cu and Zn near a non-ferrous metal smelter in Bulgaria. The hyperaccumulation levels of the metal concentrations in shoots were reached in the extremely contaminated site for Pb and Cd. The Enrichment factor was more than one for Cd in sites with low and medium level of contamination and for Zn in moderately and extremely contaminated sites. The shoot concentrations of all metals in the extremely contaminated site were between 13 and 48 times higher than in the least contaminated site.The low number of the plant feeding nematodes and the root weevil galls in the highly and extremely contaminated sites were regarded as a result of the successful elemental (heavy metals) defense of the plant against the nematode and insect herbivores. The higher number of the fungal feeding nematodes in the extremely contaminated site in the absence of the weevil root galls, might indicate a better development of the fungi associated with the roots in this site in comparison with the rest of the sites.