Effects of Copper Stress on Nitrogen Metabolism in Metallicolous and Non-Metallicolous Populations of Rumex dentatus L.

Two Rumex dentatus populations, one from copper (Cu) mine and the other from uncontaminated site, were studied for plant growth, Cu accumulation and nitrogen metabolism under Cu stress. At control, nitrate content in leaves and roots of metallicolous population (MP) showed little difference from those of non-metallicolous population (NMP). At 10 μM Cu treatment, nitrate content in leaves and roots of MP were significantly higher than those of NMP. Cu treatments significantly reduced nitrate reductase activity in leaves and roots of NMP compared with the controls while not in MP. Shoot and root biomass of NMP were inhibited more significantly than those of MP. Cu concentration in shoot and root of NMP were higher than those of MP both at control and under Cu stress. These results suggested less Cu absorbed and efficient nitrogen metabolism in MP might be partly reasons why R. dentatus can colonize Cu enriched soils.