Search

summary: This paper is the first to report cadmium tolerance in a dicotyledonous species, Silene vulgaris (Moench.) Garcke. The response to cadmium of five populations originating from one uncontaminated and various heavy‐metal contaminated sites was examined under standardized conditions for three weeks. The tolerance index (TI), based on the mean relative growth rate (R), was determined. Populations originating from cadmium‐contaminated sites showed a distinct tolerance to cadmium. A population from a site enriched only with copper also exhibited a marked co‐tolerance to cadmium. A clear difference in biomass production between the sensitive and tolerant populations was attained at 1 μM cadmium. An optimum biomass production in tolerant populations at a metal concentration higher than in the control, as demonstrated for zinc and copper, could not be established for cadmium. The pattern of cadmium uptake and translocation differed between tolerant and sensitive populations. All tolerant populations accumulated cadmium in the roots and showed some degree of restricted transport to the shoots. The effect of cadmium on the elemental distribution in roots and shoots was population‐independent for some elements (copper, zinc, potassium) and population‐specific for others (phosphorus, magnesium and sodium). The phenomenon of co‐tolerance to cadmium is discussed in relation to possible tolerance mechanisms, especially with regard to metal‐binding compounds (metallothioneins, phytochelatins). [ABSTRACT FROM AUTHOR]

Ten individuals from each of four populations of the moss, Funaria hygrometrica Hedw., were grown on tow copper and two zinc treatments and a control in order to assess tolerance to these metals. Tolerances of two life-history stages (protonemal growth and stem production) showed significant variation among populations, and among individuals within all population that originated on a copper mine. Phenotypic correlations among growth responses to the five experimental treatments were similar in the four populations, but this reflected a greater similarly among the environmental correlations than among the genotypic correlations. There was evidence of positive genetic correlations between growth of control medium and growth on media enriched with copper or zinc. This is contrast to data from flowering plants and fungi, and raises the question of why tolerant individuals are restricted to contaminated sites in nature. [ABSTRACT FROM AUTHOR]