title: Effects of pH, Fe, and Cd on the uptake of Fe(2+) and Cd (2+) by rice.
abstract: The rhizosphere plays an important role in altering cadmium (Cd) solubility in paddy soils and Cd accumulation in rice. However, more studies are needed to elucidate the mechanism controlling rice Cd solubility and bioavailability under different rhizosphere conditions to explain the discrepancy of previous studies. A rice culture with nutrient solution and vermiculite was conducted to assess the effects of pH, Eh, and iron (Fe) concentration on Cd, Fe fractions on the vermiculite/root surface and their uptake by rice. The solution pH was set from 4.5 to 7.5, with additions of Fe (30 and 50 mg L(-1)) and Cd (0.5 and 0.9 mg L(-1)). At pH 5.5, the Eh in the rice rhizosphere was higher whereas transpiration, Cd(2+), and Fe(2+) adsorption on the vermiculite/root surface and accumulation in rice were lower than the other pH treatments. Cadmium addition had no impact on pH and Eh in rice rhizosphere while Fe addition decreased pH and increased Eh significantly. Compared with control, Fe addition resulted in the decrease of rhizosphere Cd, Fe solubility and bioavailability. Higher redox potential in the rice rhizosphere resulted in the decline of transpiration, Cd, and Fe accumulation in the rice tissues, suggesting that the transfer of two elements from soil to rice was depressed when the rhizosphere was more oxidized.
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Danqing
authors.initials: D
authors.lastname: Liu
authors.forename: Chunhua
authors.initials: C
authors.lastname: Zhang
authors.forename: Xue
authors.initials: X
authors.lastname: Chen
authors.forename: Yazhou
authors.initials: Y
authors.lastname: Yang
authors.forename: Shu
authors.initials: S
authors.lastname: Wang
authors.forename: Yujiao
authors.initials: Y
authors.lastname: Li
authors.forename: Hao
authors.initials: H
authors.lastname: Hu
authors.forename: Ying
authors.initials: Y
authors.lastname: Ge
authors.forename: Wangda
authors.initials: W
authors.lastname: Cheng
mesh_terms: D000327:Adsorption; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism* / Q000633:toxicity; D012275:Oryza / Q000187:drug effects / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D058441:Rhizosphere; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000378:metabolism* / Q000633:toxicity
chemical_list: D012987:Soil; D012989:Soil Pollutants; D002104:Cadmium; D007501:Iron