INFLUENCE OF COPPER STRESS ON THE GROWTH PERFORMANCE OF EUCALYPTUS CAMALDULENSIS SEEDLINGS

Heavy metals are a group of elements to which belong micronutrients that are essential for adequate plant growth and development. In the present study our model example is copper (Cu). The accumulation of Cu salts in the environment causes toxicity to plants and ultimately Cu may find its way to human via food chain constituting a real threat to human life. The aim of this investigation was to analyze the response of Eucalyptus camaldulensis, an important tree species to Cu stress. To address this goal E. camaldulensis seedlings were maintained in long soil columns under nursery conditions and exposed to a wide range of Cu treatments: 0 (control), 10, 30, 50 and 80 μM Cu (supplemented as CuSO4.5H2O for 4 weeks). Growth performance was monitored before and after Cu exposure. Growth data were obtained by measuring plant shoot height, stem diameter and leaf formation regularly once a week and the growth rates were determined. At harvest, each plant was separated into root and shoot systems to evaluate Cu effect on biomass production, accumulation and partitioning. Dry mass was subsequently determined for all plant fractions. Leaf formation rate was drastically reduced and the effect was most pronounced in plants which received the highest Cu level. Similar patterns were observed for both shoot height and stem diameter growth rates. Total plant dry mass as well as rootto- shoot were significantly reduced in response to Cu treatments, especially in seedlings exposed to the highest Cu concentrations. These findings might suggest that E. camaldulensis is sensitive to Cu stress. Further experiments to validate this speculation are required to elucidate the physiological events responsible for the poor performance of E. camaldulensis under Cu-polluted soils.