Abstract: [Objective]The aim of the present study was to investigate the bacterial structure and diversity of rhizosphere soil of different plantations and their influencing factors in Yellow River Delta.[Method]Based on the high throughput sequencing technology, this research compared the rhizosphere soil bacterial community structure and diversity of Ailanthus altissima, Ulmus pumila, Fraxinus velutina, Robinia pseudoacacia, and analysed correlation with soil properties.[Result]The results of high throughput sequencing showed that there were 27, 26, 28, and 28 phylum bacteria in the rhizosphere soil of A. altissima, U. pumila, F. velutina, and R. pseudoacacia. Acidobacteria, Proteobacteria, and Actinobacteria were dominant bacteria taxa with their relative abundance more than 10%, and Nitrospirae, Chloroflexi, Planctomycetes, Gemmatimonadetes, and Verrucomicrobia were main bacteria taxa with their relative abundance more than 1%. There was significant difference in the relative abundance of Proteobacteria, WS3, Cyanobacteria, Euryarchaeota, Firmicutes, OD1, and Tenericutes in the rhizosphere soil among different plantations. The results of high throughput sequencing showed that the rhizosphere soil bacterial diversity of R. pseudoacacia plantation was highest among four plantations, and the observed species number, Chao1 index, Shannon index and Simpson index were 1 828.489, 2 602.806, 8.917 and 0.95, respectively, its Simpson index was lowest among four plantations. Observed species number (1 703.36) in U. pumila plantation, Chao1 index (2 161.69) in F. velutina plantation was lowest among four plantations. The rhizosphere soil bacterial Shannon index of A. altissima was lowest among four plantations with 8.73, and Simpson index was highest with 0.98. The results showed available P (1.17 mg·kg^-1), K (163 mg·kg^-1), N (30.47 mg·kg^-1), and organic matter (4.4 g·kg^-1) content of U. pumila plantation were lowest among four plantations. Available P (3.47 mg·kg^-1) content of R. pseudoacacia plantation was highest. Soil pH (8.52), water content (13.10%), Available K (330.00 mg·kg^-1), N (48.63 mg·kg^-1), and organic matter (74.83 g·kg^-1) content of A. altissima plantation were highest, especially, soil water content and organic matter (74.83 g·kg^-1) content were significantly higher than other 3 plantations. The results of correlation analyses showed that there were significant correlations between the content of conductivity, soil water content, available P, N, organic matter and bacterial diversity among four plantations, but the correlation between pH and bacterial diversity was not significant.[Conclusion]The bacterial structure in rhizosphere soil of different plantations was similar, but there was a significant difference in the relative abundance of some bacteria at phylum level. The rhizosphere soil bacterial diversity of R. pseudoacacia was highest among four plantations. Conductivity, soil water content, and available P, N, K content were the main soil factors that affect the soil bacterial structure and diversity. But further research is also needed to obtain more information in soil microorganisms.

Key words: Yellow River Delta, bacteria, high throughput sequencing, soil, structure, diversity