title: Elevated CO2 increases Cs uptake and alters microbial communities and biomass in the rhizosphere of Phytolacca americana Linn (pokeweed) and Amaranthus cruentus L. (purple amaranth) grown on soils spiked with various levels of Cs.
abstract: General concern about increasing global atmospheric CO(2) levels owing to the ongoing fossil fuel combustion and elevated levels of radionuclides in the environment, has led to growing interest in the responses of plants to interactive effects of elevated CO(2) and radionuclides in terms of phytoremediation and food safety. To assess the combined effects of elevated CO(2) and cesium contamination on plant biomass, microbial activities in the rhizosphere soil and Cs uptake, Phytolacca americana Linn (pokeweed, C3 specie) and Amaranthus cruentus L. (purple amaranth, C4 specie) were grown in pots of soils containing five levels of cesium (0, 100, 300, 500 and 1000 mg Cs kg(-1)) under two levels of CO(2) (360 and 860 μL L(-1), respectively). Shoot and root biomass of P. americana and Amaranthus crentus was generally higher under elevated CO(2) than under ambient CO(2) for all treatments. Both plant species exhibited higher Cs concentration in the shoots and roots under elevated CO(2) than ambient CO(2). For P. americana grown at 0, 100, 300, 500 and 1000 mg Cs kg(-1), the increase magnitude of Cs concentration due to elevated CO(2) was 140, 18, 11, 34 and 15% in the shoots, and 150, 20, 14, 15 and 19% in the roots, respectively. For A. cruentus, the corresponding value was 118, 28, 21, 14 and 17% in the shoots, and 126, 6, 11, 17 and 22% in the roots, respectively. Higher bioaccumulation factors were noted for both species grown under elevated CO(2) than ambient CO(2). The populations of bacteria, actinomycetes and fungi, and the microbial C and N in the rhizosphere soils of both species were higher at elevated CO(2) than at ambient CO(2) with the same concentration of Cs. The results suggested that elevated CO(2) significantly affected plant biomass, Cs uptake, soil C and N concentrations, and community composition of soil microbes associated with P. americana and A. cruentus roots. The knowledge gained from this investigation constitutes an important advancement in promoting utilization of CO(2) fertilization for improvement of phytoextraction of soils contaminated with radionuclides.
authors.affiliation: Centre for Research in Ecotoxicology and Environmental Remediation, Agro-Environmental Protection Institute, Ministry of Agriculture, No. 31, Fukang Rd, Nankai District, Tianjin 300191, PR China.
authors.forename: Ningning
authors.initials: N
authors.lastname: Song
authors.forename: Ximei
authors.initials: X
authors.lastname: Zhang
authors.forename: Fangli
authors.initials: F
authors.lastname: Wang
authors.forename: Changbo
authors.initials: C
authors.lastname: Zhang
authors.forename: Shirong
authors.initials: S
authors.lastname: Tang
mesh_terms: D027721:Amaranthus / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D002244:Carbon / Q000032:analysis; D002245:Carbon Dioxide / Q000494:pharmacology*; D002586:Cesium / Q000378:metabolism*; D002588:Cesium Radioisotopes / Q000378:metabolism; D002681:China; D009584:Nitrogen / Q000032:analysis; D029604:Phytolacca americana / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D011834:Radiation Monitoring; D058441:Rhizosphere; D012988:Soil Microbiology; D012990:Soil Pollutants, Radioactive / Q000378:metabolism*; D013045:Species Specificity; D013054:Spectrophotometry, Atomic
chemical_list: D002588:Cesium Radioisotopes; D012990:Soil Pollutants, Radioactive; D002245:Carbon Dioxide; D002586:Cesium; D002244:Carbon; D009584:Nitrogen