Cu-ions mediated changes in growth, chlorophyll and other ion contents in a Cu-tolerantKoeleria splendens

The effects of Cu2+ on growth, chlorophyll and other ion contents ofKoeleria splendens originated from Cu-contaminated soil have been investigated in nutrient solution. The most evident Cu2+ effects concern the root growth, especially the root length. Since in plants grown under lower Cu2+ concentrations (4 and 8 μM) root elongation, biomass, chlorophyll, Mg2+, Fe2+, Ca2+ and K+ content were increased compared with the control, the development of an adaptive mechanism ofK. splendens to Cu2+ is suggested. High Cu2+ concentration (160 μM) caused a significant reduction in root length and biomass as well as a decreased rate of chlorophyll biosynthesis. The reduction of growth can be correlated with the toxic effect of Cu2+ on photosynthesis, root respiration and protein synthesis in roots. 160 μM Cu2+-treatment had a negative influence on the concentrations of Ca2+, Fe2+, Mg2+ and K+ and a positive influence on the Cu2+ concentration in the plant tissues. Loss of nutrients similar to the senescence response suggests that excess of Cu2+ leads to the progressive senescence of the plants. Our results demonstrate the existence of an adaptive mechanism ofK. splendens under low Cu2+ concentrations, while high Cu2+ quantities cause disturbances in plant function.