Differences in accumulation and physiological response to copper stress in three populations of Elsholtzia haichowensis S.

Copper accumulation and physiological responses to Cu stress in three populations of Elsholtzia haichowensis S. were comparatively studied with pot culture experiments. Seeds of the three populations were respectively collected from Cu contaminated and non-contaminated sites. It was found that the copper accumulation and physiological responses to Cu treatment in the three populations were significantly different. The chlorophyll content and electrolyte leakage were less affected in the populations from contaminated sites than those in the population from non-contaminated site. At high level of copper treatment, the activities of peroxidase and superoxide dismutase in the populations from contaminated sites were significantly induced, while this was not the case for the population from non-contaminated site. Lower copper content was noted in the leaves of plants from contaminated site exposed to higher Cu concentrations when compared to controls. These results indicate that the populations from Cu-contaminated sites are more resistant to copper stress. The reason for this might be related to the fact that, in the populations from Cu-contaminated sites, less Cu was transported to leaves and higher peroxidase and superoxide dismutase activities induced in the plants when subjected to Cu stress.