Effects Of Flooding Regime Combine Amendments Application On Bacteria Community Structure In Rice Rhizosphere Under Cd-Pb-Zn Contaminated Soil

In order to investigate the effects of flooding regime combine amendments application on bacteria community diversity in rice rhizosphere under Cd-Pb-Zn contaminated soil.Utilise 16S rRNA high-through-sequence technology to explore heavy metal biochemical process in rice rhizosphere from tillering to ripening satge.Thisplots experiment contained two rice cultivations(TY009 and TJ9),and two flooding conditions control(continuous flooding and intermittent flooding)and biochar or lime applicated in the contaminated soil,respectively.Primary results as follow:(1)Flooding regime did not significant impact on a diversity of bacteria community,but bacteria structure andrichness.At phylum taxa level,flooding regime performed no effects on essential bacteria community structure or relative abundance.At class taxa level,different flooding treatments could significant impact on the relative abundance of Deltaproteobacteria,which contribute to continuous flooding could maintain higher abundance of Myxococcaceae,Geobacteraceae and Desulfovibrionaceae in rice rhizosphere.(2)From correlation analysis results,effects of rice root uptake Cd,Pb and Ni are primary from inorganic elements contents and richness of bacteria in rhizosphere.For one hand,intermittent flooding treatments could enhance available phosphous content,which contribute Pb an Ni to immobility to suppress rice rootuptake,while for another,continuous flooding treatments could maintain higer richness of iron reducing bacteria and sulfur reducing bacteria community than ntermittent flooding treatments,leading to ferric mineral dissovled and release other metals(eg.Pb,Ni)for root to uptake.Biochar and lime amendingcontaminated soil could significant decline bio-available heavy metal contents.(3)With 0.25%biochar or 4%lime addition amending the soil,two kinds of amendments did not significant affect on the a diversity of bacteria community,but the relative abundance of bacteria community shown apparent change.At phylum taxa levels,biochar or lime adding in the soil,did not affect on the bacteria community conpone and relative abundance.At class taxa level,liming treatments could significant suppress the relative abundance of Acidobacteria,which may due to the Acidobacteriaceae and Koribacteraceae perform sensitive on pH and available phosphous contents in soil.(4)Combining flooding regime and amendment technology on heavy metal contaminated soil,pH and available phosphous mobility plays a critical role on rice root accumulated heavy metals,in addition,iron reducing bacteria and sulfur reducing bacteria community also impact on root uptake metal elements through reaction of metabolic process and environmental factors.(5)Fooding regime could significant affect on rice root accumulated heavy metal from soil.For instence,continuous flooding treatments could significant decrease the root accumulated Cd.Howerver root Pb and Ni contents under intermittent flooding is lower than continuous flooding treatments.From the results of 0.25%biochar or 4%lime addition amending the soil,Under continuous flooding treatments,the efficiency of the two amendments decrease bio-available heavy metal contents is that biochar?lime>control,while under IF treatments,the efficiency of the two amendments is that lime>biochar>control.For rice cultivated,under continuous flooding condition,the root in control treatments uptake Cd contents is lowest;under IF and biochar applicated,leading the root to uptake Pb and Ni is lower;limeapplicated could contribute root to accumulate Zn lower.