中文摘要：

根际土壤微生物是根际土壤生态系统的重要组成部分，与根际养分有效性、植物生长发育等关系密切。土壤磷素营养的差异可引起植物根系分泌物和根形态的变化，但对植物根际微生物的作用还少有报道。在盆栽条件下，研究了3种磷浓度处理对生长在黑土土壤上3个采样时期（V3、R1和R3期）的大豆根际微生物群落结构的影响。采用PCR-DGGE技术对细菌16S rDNA和真菌ITS片段进行解析，对DGGE图谱主成分分析（PCA）。结果表明：大豆根际土壤细菌和真菌群落结构均随生育期而迁移，说明生育时期较磷浓度处理而言是影响根际微生物群落结构产生变化的主要因素；大豆根际真菌群落结构受不同磷浓度处理产生分异体现在V3期，细菌结构产生分异体现在V3和R1期，说明磷浓度处理对大豆根际微生物的影响主要表现在大豆生育的早期，随着生育时期的推进，这种差异弱化至不明显。

英文摘要：

Microbial community in the rhizosphere play an important role in soil nutrient availability and plant growth. Different concentrations of phosphorus availability change the root exudates and root architecture;however,the effect on microbial community in the rhizophere is unclear. In this study, a pot experiment was conducted to investigate the effects of three phosphorus concentrations on soybean rhizosphere microbial communities at three sampling times （V3, R1 and R3）. The bacterial and fungal communities were analyzed by PCR-DGGE （polymerase chain reaction-degenerate gradient gel electrophoresis） targeting a partial 16S rDNA and the internal transcribed space （ITS） region, respectively. DGGE banding patterns were used for principal component analysis （PCA）. Results showed that both bacterial and fungal communities shifted with growth stages, suggesting that the growth stage play a more important role in determination of soybean rhizosphere microbial community than different phosphorus concentration treatments. Furthermore, the impact of different phosphorus treatments on microbial community change was only detected at soybean early growth stages,i, e. , for fungal community at stage V3 and for bacterial community at stages V3 and R1. No significant difference of microbial community among phosphorus treatments was observed at growth stage R3.