Growth and cesium uptake responses of Phytolacca americana Linn. and Amaranthus cruentus L. grown on cesium contaminated soil to elevated CO2 or inoculation with a plant growth promoting rhizobacterium Burkholderia sp D54, or in combination

Growth and cesium uptake responses of plants to elevated CO2 and microbial inoculation, alone or in combination, can be explored for clean-up of contaminated soils, and this induced phytoextraction may be better than the natural process. The present study used open-top chambers to investigate combined effects of Burkholderia sp. D54 inoculation and elevated CO2 (860 mu L L-1) on growth and Cs uptake by Phytolacca americana and Amaranthus cruentus grown on soil spiked with various levels of Cs (0-1000 mg kg(-1)). Elevated CO2 and bacterial inoculation, alone or in combination, significantly increased biomass production with increased magnitude, ranging from 22% to 139% for P. americana, and 14% to 254% for A. cruentus. Total tissue Cs in both plants was significantly greater for bacterial inoculation treatment singly, and combined treatments of bacterial inoculation and elevated CO2 than for the control treatment in most cases. Regardless of CO2 concentrations and bacterial inoculation. A. cruentus had higher tissue Cs concentration, Cs transfer factors and concentration ratios than P. americana, but they had slightly different contents of antioxidant enzymes. It is concluded that combined effects of elevated CO2 and microbial inoculation with regard to plant ability to grow and remove radionuclides from soil can be explored for CO2- and microbe-assisted phytoextraction technology. (C) 2011 Elsevier B.V. All rights reserved.