To explore the effects of different aeration methods on the abundance of microorganisms and microorganism community structure in rice rhizosphere soil, two rice varieties, Miyang 46(MY) and Zhenshan 97B(ZS), were used with three aeration treatments:alternate wetting and drying(AWD), continuous flooding and aeration(CFA), and continuous flooding(CF). The diversity of bacterial and fungal communities in rice rhizosphere soil was analyzed using Illumina MiSeq high-throughput sequencing. Soil physical and chemical factors were also analyzed. The results showed that the dominant bacterial communities in rice rhizosphere soil were Chloroflexi, Actinobaciota, Acidobacteria, Proteobacteria, and Firmicutes, and the dominant fungal communities were Ascomycota and Basidiomycota in rice rhizosphere soil. At each growth stage, the relative abundance of Chloroflexi and Acidobacteria was higher in the AWD treatment than in the other treatments, and the relative abundance of Actinobaciota was higher in the CFA treatment than in the other treatments. The relative abundance of Firmicutes was lower in the AWD treatment than in the other treatments. Aeration methods affected the diversity and richness of rhizosphere microbial species. For example, the diversity of bacterial species was higher, and the richness of bacterial species was lower in the AWD treatment than that in the other treatments. The diversity and richness of fungal species were higher in the AWD and CFA treatments than those in the CF treatment. The physical and chemical properties of rhizosphere soil were also affected by aeration method. The soil redox potential(Eh) was the highest in AWD, followed by that in CFA and CF, and significant differences were observed among treatments. The NO3--N content was significantly higher, and the NH4+-N content was significantly lower in the AWD and CFA treatments than in the CF treatment in rhizosphere soil at all growth stages. Correlation analysis showed that the pH and Eh of rhizosphere soil were positively correlated with the diversity of bacterial species, negatively correlated with the richness of bacterial species, and positively correlated with the diversity and richness of fungal species. Redundancy analysis indicated that the relative abundance of Chloroflexi was positively correlated with the pH and NH4+-N content at each period, positively correlated with the Eh and NO3--N content at the tillering and heading stages, and negatively correlated with Eh and NO3--N content at the maturity stage. At each growth stage, the pH and Eh were positively correlated with the relative abundance of Acidobacteria, Proteobacteria, and Basidiomycota and negatively correlated with the relative abundance of Firmicutes and Ascomycota. During the entire growth period, the relative abundance of Ascomycota was negatively correlated with the NO3--N content and positively correlated with the NH4+-N content, and the opposite patterns were observed for the relative abundance of Basidiomycota. In summary, rhizosphere oxygenation enhanced the soil oxygen environment, altered soil physical and chemical properties, and affected microbial community diversity and richness to optimize microbial community structure.
Keywords: aeration methods; microbial community structure; microbial diversity; redundancy analysis; rhizosphere soil.