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Adsorption of Iron and Cadmium in Rhizosphere of and Their Uptake and Translocation in Rice Pretreated with Iron Deficiency
  
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KeyWord:rice; iron deficiency; rhizosphere; iron; cadmium; adsorption; uptake; translocation
Author NameAffiliation
LIU Dan-qing College of Resource and Environmental Science, Nanjing Agricultural University, Nanjing 210095, China
Shanghai Environmental Monitoring Center, Shanghai 200030, China 
CHEN Xue College of Resource and Environmental Science, Nanjing Agricultural University, Nanjing 210095, China 
GE Ying College of Resource and Environmental Science, Nanjing Agricultural University, Nanjing 210095, China
State Key Laboratory of Soil and Sustainable Agriculture, Nanjing Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China 
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Abstract:
      Cadmium(Cd) accumulation in rice poses a serious risk to human health. Cadmium bioavailability may be affected by the chemistry of iron(Fe) in rice rhizosphere. Here we investigated the effects of rhizospheric conditions and low molecular weight organic acids(LMWOAs) secreted from rice roots with iron deficiency pretreatment on Cd and Fe adsorption on the vermiculite/root surface and their uptake and translocation by rice using nutrient solution-vermiculite culture. Pretreatment with Fe deficiency increased acidity and reducing condition in the rhizosphere, but decreased amount of LMWOAs. Iron deficiency had little influence on Fe adsorption on the surface of vermiculite, but decreased that on the rice root. Compared with normal Fe, Fe deficiency caused increases in non-crystalline Cd on the vermiculite, whereas had no impact on Cd in the Fe film. Enhanced concentration and accumulation of Cd in rice root suggested that Fe deficiency resulted in less competition of these two elements in the rhizosphere and on the roots. Iron plaque on rice roots showed limited shielding effect on Cd uptake by rice, leading to increased Cd absorption by rice. However, Fe deficiency decreased the Cd and Fe translocation from roots to shoots, maybe due to declined LMWOA carriers in rice roots.