Variance of microbial composition and structure and relation with soil properties in rhizospheric and non-rhizospheric soil of a flooded paddy

Abstract

Soil microbial structure and nutrient properties varied with fertilization and plant growth simultaneously in the rhizosphere. However, the relationships between rhizospheric microbial community structure and soil characteristics were still unclear. This study aimed to explore the impact of nitrogen (N) fertilizer and rice growth on microbial community structure and their relation with soil physiochemical properties. A pot experiment for rice-planting with two levels of N fertilization was conducted in a flooded paddy soil. At tillering and ripening stages, both rhizospheric and non-rhizospheric soils were sampled separately for physiochemical analysis, real-time quantitative PCR assay and terminal restriction fragment length polymorphism (T-RFLP) analysis. The results showed that both N addition and growth stage of rice could affect physiochemical properties of rhizosphere and non-rhizosphere soil simultaneously. At tillering stage, no significant difference of bacterial and archaeal gene abundance was observed, but rhizospheric abundance of microorganisms was significantly different with non-rhizosphere at ripening stage. One-way ANOVA analysis indicated that N addition has greater effect on microbial structure diversity of bacteria rather than archaea, non-rhizosphere than rhizosphere, respectively. Non-metric multidimensional scaling analysis showed two groups of bacterial community both in rhizospheric and in non-rhizospheric soils at tillering stage differing much, but similar at ripening stage. Redundancy analysis showed that the microbial community compositions at tillering stage were most correlated with NH4+, total N (TN), pH, microbial biomass N (Nmic) and microbial biomass carbon (Cmir) whereas at ripening stage were more or less lined with Olsen-P, C/N ratio, total C (TC) and available K. Our research suggested that the N addition has more influence on community composition diversity of bacteria and non-rhizosphere. The growth stage might be the main factor affecting bacterial community structure both in rhizospheric and in non-rhizospheric soils affected by different soil parameters.