Strategies of adaptation to heavy metal pollution in Deschampsia caespitosa and Lychnis flos-cuculi: Analysis based on dose-response relationship

Abstract

The response to copper pollution was studied in the vegetative progeny of tufted hair grass (Des� champsia caespitosa (L.) Beauv.) and ragged robin (Lychnis floscuculi L.) plants growing together in chron� ically polluted areas around the Middle Ural Copper Smelter or in background areas. The root elongation test was used, with copper sulfate (0.006-0.51 mg Cu/L) being added directly to the nutrient medium. Using multimodel inference, dose-response curves were plotted for each of 85 maternal plants, and their parame� ters (effective Cu concentrations and curve slope in the linear segment) were evaluated. The pattern of trans� formation in dose dependence of root increment upon transition from background to impact populations proved to be basically different in the two species. The curves for L. floscuculi showed a parallel shift, with their shape remaining generally unchanged. In D. caespitosa, this transition was accompanied by a decrease in sensitivity to Cu, but tolerance to this metal was found to increase only at the highest concentration range. These results provide evidence for different strategies of adaptation to heavy metal pollution, which are dis� cussed by comparing the physiological and ecological properties of the two species.