Response Of Ecological And Physical Characteristics To Elevated Co₂and Pb Stress In Reed

It is forecasted that atmospheric CO2concentration is continuing to increase and will be doubled by the end of this century. On the other hand. the heavy metal pollution of soil is also a worldwidely serious environmental problem. It is inevitable that elevated CO2and heavy metal concentration will affect the growth and development of plant. So. we studied the response of phragmites australis to the Pb stress under elevated CO2concentration. The subjects of this study was to reveal the combined effect of elevated CO2and Pb on the reed in term of growth, bud bank, photosynthesis, Pb accumulation. This would provide a new knowledge to well understand the physio-ecological response of reed to Pb and the ability of Pb absorption under the elevated CO2. The whole experiment was finished in the ecological simulation laboratory of Grassland Institute at Northeast Normal University.We get some important conclusions, as the followings were:(1) Whether under control CO2concentration or doubled CO2concentration, lower Pb concentration promoted plant growth of reed, while higher Pb concentrations inhibited plant, such as the significantly reduced plant height, node number of steam, number of leaves and root length. Under doubled CO2concentration, the above-ground biomass was increased, however the below-ground biomass was reduced as a result of the increased total biomass. Above these results showed that elevated CO2could ease the phytotoxic effects of Pb(2) Whether atmospheric CO2(control) or doubled CO2concentration, lower Pb concentration can promote photosynthesis, but stomatal conductance and transpiration rate were reduced with increasing Pb concentrations. On the contrary, net photosynthetic rate and intercellular CO2concentration were increased under doubled CO2concentration conditions. So elevated CO2promoted photosynthesis was, alleviating the toxic effects of Pb towards reed.(3) Under doubled CO2concentration conditions, Pb concentration in reed roots was increased significantly, but were reduced in stems and leaves, as a consequence of the increased total Pb concentration in reed. These results showed that elevated CO2can promote to Pb accumulation of reed.All in all, the elevated CO2can ease the toxic effects of Pb towards reed. This would play a significant role to understand the response of reed to Pb stress under elevated CO2. On the other hand, this can supply the theoretical support for applying CO2fertilization technology to improve the efficiency of phytoremediation.