Rice Rhizopshere Soil and Root Surface Bacterial Community Response to Water Managment Changes.

Different water management practices could affect microbial populations in the rice rhizosphere. A field-scale study was conducted to evaluate microbial populations in the root plaque and rhizosphere of rice in response to continuous and intermittent flooding conditions. Microbial populations in rhizosphere and root-plaque samples were enumerated with a quantitative PCR study and bacterial communities were studied by pyrosequencing the 16S rRNA sequences. Quantitative PCR indicated that Bacteria dominated all samples representing 91-94% and 48–78% of the total community in root plaque and rhizosphere, respectively, with smaller proportions of Archaea and Fungi being detected. The relative abundance of iron-reducing bacteria was lower in rhizosphere under intermittent than continuous flooding. The 16S rRNA gene sequencing indicated that bacterial community composition was significantly different among the two water management systems. Proteobacteria was the predominant phylum in root plaque (51–57%) and most rhizosphere samples (23–27%).  Chloroflexi (20–28%) were also dominant in rhizosphere samples, and their populations increased in response to intermittent flooding. These results indicated that intermittent flooding can alter root plaque and rhizosphere microbial communities.