Effect of water-driven changes in rice rhizosphere on Cd lability in three soils with different pH |
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Authors: | Jinjin Wang Dongqin Li Qin Lu Yulong Zhang Huijuan Xu Xueli Wang Yongtao Li |
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Institution: | College of Natural Resources and Environment, Joint Institute for Environmental Research & Education, South China Agricultural University, Guangzhou 510642, China;College of Natural Resources and Environment, Joint Institute for Environmental Research & Education, South China Agricultural University, Guangzhou 510642, China;Life Science and Technology School, Lingnan Normal University, Zhanjiang 524048, China;College of Agriculture, Guangxi University, Nanning 530004, China |
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Abstract: | Pot experiments were conducted to evaluate the effect of water management,namely continuous flooding(CF),intermittent flooding(IF) and non-flooding(NF),on Cd phytoavailaility in three paddy soils that differed in p H and in Cd concentrations.Diffusive gradients in thin films(DGT) technique was employed to monitor soil labile Cd and Fe concentrations simultaneously at three growth stages(tillering,heading and mature stage)of rice.The Cd phytoavailability were generally in the order of NF IF CF,and higher rice Cd(over permitted level,0.2 mg/kg) were only found in neutral and acidic soils under NF conditions.DGT measured soil labile Cd rather than total Cd was the most reliable predictor for Cd accumulation in rice.CF enhanced the formation of root plaques,which related to oxidation of large quantities of available Fe on root surfaces due to the O2 secretion of rice root.The Cd concentration in root plaques shared the same trend with DGT-Cd.Generally,root plaques would inhibit Cd uptake by rice under CF conditions,while under IF and NF conditions,root plaques act as a temporarily store of Cd,and soil labile Cd is the key factor that controls the transfer of Cd from soil to rice.The results of principle component analysis revealed that water management had the greatest effect on soil Cd lability and rice Cd in acidic soil.Thus,it is important to consider the availability of Cd and soil p H when assessing current agricultural practices of contaminated soil in China. |
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Keywords: | Corresponding author Cadmium lability Rhizosphere Rice Water management Root plaque DGT technique |
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