Arsenic(As)contamination in paddy soils has posed a prominent threat to rice production in Asia.Recycling of silicon(Si)from Si-rich combusted rice husk(CRH)could serve as a sustainable strategy to mitigate rice As up...Arsenic(As)contamination in paddy soils has posed a prominent threat to rice production in Asia.Recycling of silicon(Si)from Si-rich combusted rice husk(CRH)could serve as a sustainable strategy to mitigate rice As uptake through their shared transport pathway.Root(soil)application of CRH alone,however,was insufficient to decrease inorganic As(iAs)in polished rice below Chinese food standards(0.2 mg kg^(-1)).In this study,an aqueous Si solution derived from CRH was used for synergistic foliar application over the highest Si-demanding stage(reproductive stage)of rice,following root application of Si,to investigate rice As uptake in both pot and field experiments.In the pot experiment,on the basis of root application of CRH,Si supplementation before the reproductive stage of rice led to a 51%decrease in As concentration on root surface along with a prominent reduction of Fe plaque due to enhanced root suberization,relative to single root application of CRH treatment.In parallel,the expression of OsLis6 gene in the root was downregulated by 91%than that with only root application of CRH.These changes decreased As influx into root by 56%and led correspondingly to 41%lower As transfer to the straw,as compared with root application of CRH treatment.In node I,the expression of OsLis6 decreased concurrently by 71%,leading ultimately to 28%lower iAs accumulation in grains than that with root application of CRH alone.In the field experiment,with single foliar Si,the mitigation of grain iAs occurred only at lower soil As level of 40 mg kg^(-1),while promoted iAs unloading into grains was determined under higher soil As level(80 mg kg^(-1))relative to the control without Si application.It was,therefore,concluded that the mitigation of grain iAs accumulation with soil application of CRH can be strengthened critically by synergistic supply of foliar Si,serving as a more reliable pathway to secure rice production in As-contaminated paddy fields.展开更多
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 a...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.展开更多
Accumulations of copper （Cu） and cadmium （Cd） in six rice cultivars （94D-22, 94D-54, 94D-64, Gui630, YY-1, and KY1360） were evaluated through exposure to heavy metal contamination （100 mg/kg Cu, 1.0 mg/kg Cd, a...Accumulations of copper （Cu） and cadmium （Cd） in six rice cultivars （94D-22, 94D-54, 94D-64, Gui630, YY-1, and KY1360） were evaluated through exposure to heavy metal contamination （100 mg/kg Cu, 1.0 mg/kg Cd, and 100 mg/kg Cu ＋ 1.0 mg/kg Cd） in a greenhouse. The dry weights of shoot and root, concentrations of Cu and Cd in plant tissues and the Cu, Cd, P, Fe concentrations in the root surface iron plaques were analyzed eight weeks later after treatment. The results indicated that the plant biomass was mainly determined by rice genotypes, not Cu and Cd content in soil. Separated treatment with Cu/Cd increased each metal level in shoot, root and iron plaques. Soil Cu enhanced Cd accumulation in tissues. In contrast, Cu concentrations in shoot and root was unaffected by soil Cd. Compared to single metal contamination, combined treatment increased Cd content by 110.6%, 77.0%, and 45.2% in shoot, and by 112.7%, 51.2% and 18.4% in root for Gui630, YY-1, and KY1360, respectively. The content level of Cu or Cd in root surface iron plaques was not affected by their soil content. Cu promoted Fe accumulation in iron plaques, while Cd has no effect on P and Fe accumulation in it. The translocation of Cu and Cd from iron plaques to root and shoot was also discussed. These results might be beneficial in selecting cultivars with low heavy metal accumulation and designing strategies for soil bioremediation.展开更多
基金supported by the National Natural Science Foundation of China(No.42377024)the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province,Chinathe Key Project of Developmental Biology and Breeding from Hunan Province of China(No.2022XKQ0207).
文摘Arsenic(As)contamination in paddy soils has posed a prominent threat to rice production in Asia.Recycling of silicon(Si)from Si-rich combusted rice husk(CRH)could serve as a sustainable strategy to mitigate rice As uptake through their shared transport pathway.Root(soil)application of CRH alone,however,was insufficient to decrease inorganic As(iAs)in polished rice below Chinese food standards(0.2 mg kg^(-1)).In this study,an aqueous Si solution derived from CRH was used for synergistic foliar application over the highest Si-demanding stage(reproductive stage)of rice,following root application of Si,to investigate rice As uptake in both pot and field experiments.In the pot experiment,on the basis of root application of CRH,Si supplementation before the reproductive stage of rice led to a 51%decrease in As concentration on root surface along with a prominent reduction of Fe plaque due to enhanced root suberization,relative to single root application of CRH treatment.In parallel,the expression of OsLis6 gene in the root was downregulated by 91%than that with only root application of CRH.These changes decreased As influx into root by 56%and led correspondingly to 41%lower As transfer to the straw,as compared with root application of CRH treatment.In node I,the expression of OsLis6 decreased concurrently by 71%,leading ultimately to 28%lower iAs accumulation in grains than that with root application of CRH alone.In the field experiment,with single foliar Si,the mitigation of grain iAs occurred only at lower soil As level of 40 mg kg^(-1),while promoted iAs unloading into grains was determined under higher soil As level(80 mg kg^(-1))relative to the control without Si application.It was,therefore,concluded that the mitigation of grain iAs accumulation with soil application of CRH can be strengthened critically by synergistic supply of foliar Si,serving as a more reliable pathway to secure rice production in As-contaminated paddy fields.
基金supported by the National Natural Science Foundation of China(Nos.41601533 and U1401234)the Guangdong Natural Science Foundation(No.2017A030313241)
文摘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.
基金supported by the National Natural Sci-ence Foundation of China (No. 30671204, 40620120436)the Tianjin Specific Fund for Scientific and Technolog-ic innovation (No. 06FZZDSH00900)and the Hi-TechResearch and Development program (863) of China (No.2007AA061001).
文摘Accumulations of copper （Cu） and cadmium （Cd） in six rice cultivars （94D-22, 94D-54, 94D-64, Gui630, YY-1, and KY1360） were evaluated through exposure to heavy metal contamination （100 mg/kg Cu, 1.0 mg/kg Cd, and 100 mg/kg Cu ＋ 1.0 mg/kg Cd） in a greenhouse. The dry weights of shoot and root, concentrations of Cu and Cd in plant tissues and the Cu, Cd, P, Fe concentrations in the root surface iron plaques were analyzed eight weeks later after treatment. The results indicated that the plant biomass was mainly determined by rice genotypes, not Cu and Cd content in soil. Separated treatment with Cu/Cd increased each metal level in shoot, root and iron plaques. Soil Cu enhanced Cd accumulation in tissues. In contrast, Cu concentrations in shoot and root was unaffected by soil Cd. Compared to single metal contamination, combined treatment increased Cd content by 110.6%, 77.0%, and 45.2% in shoot, and by 112.7%, 51.2% and 18.4% in root for Gui630, YY-1, and KY1360, respectively. The content level of Cu or Cd in root surface iron plaques was not affected by their soil content. Cu promoted Fe accumulation in iron plaques, while Cd has no effect on P and Fe accumulation in it. The translocation of Cu and Cd from iron plaques to root and shoot was also discussed. These results might be beneficial in selecting cultivars with low heavy metal accumulation and designing strategies for soil bioremediation.
