COPPER TOLERANCE IN NEW-JERSEY POPULATIONS OF AGROSTIS-STOLONIFERA AND PARONYCHIA-FASTIGIATA

Populations of A. stolonifera and P. fastigiata in the vicinity of an abandoned New Jersey [USA] copper mine were examined with respect to the nature (phenotypic plasticity or population differentiation) of their apparent tolerance to high amounts of soil Cu. Field studies were 1st undertaken to determine the soil characteristics of the contaminated and uncontaminated areas and to determine the cover and frequency of the different species in relation to these soil factors. Cu was the only significant variable among these soils, and the 2 study species were most important where the amount of soil Cu ranged between 64-304 ppm. Greenhouse experiments comparing responses of seed and vegetative material collected from Cu populations and non-Cu populations to soils from the mining site containing levels of Cu ranging from 98-1024 ppm indicated a striking difference between the 2 species. A. stolonifera not only demonstrated a greater degree of tolerance but also showed population differentiation. In responses to increasing levels of Cu, the Cu population was superior in height and shoot weight of clonal materials, seedling survival and height, and ability of rhizomes and roots to immobilize Cu. Differences in tolerance between Cu and non-Cu populations of P. fastigiata were not evident.