Effects of different slope aspects on Coffea arabica L. rhizospheric soil physical and chemical properties and microbial communities

【Objective】To study rhizosphere soil physicochemical properties and microbial communities in different slopes of 4 main producing areas in Yunnan, which could provide theoretical basis for improving the sustainable management and production of fine C. arabica. 【Method】The rhizosphere soil physical and chemical properties of C. arabica were measured on the north and south slopes of four main C. arabica producing areas(Dehong,Lincang,Pu'er and Baoshan) in Yunnan. In addition,community structure and diversity of bacteria and fungi were analyzed based on 16S rRNA and ITS sequences of rhizosphere soil microorganisms. Meanwhile,the effects of physical and chemical properties of rhizosphere soil on microbial communities were analyzed. 【Result】The extremely significant difference in the electrical conductivity,hydrolytic nitrogen and available potassium among the rhizosphere soils were displayed between the north and south slopes in the four main producing areas(P<0.01,the same below). The organic matter content showed extremely significant difference in the rhizosphere soils between north and south slopes of Dehong and Baoshan. The available phosphorus demonstrated extremely significant difference in the rhizosphere soils between north and south slopes of Dehong,Lincang and Pu'er. The rhizosphere soil nutrient elements were more enriched in the north slopes compared with the south slopes of the four main producing areas. A total of 24 and 16 bacterial and fungal phyla in rhizosphere soil were detected. The dominant bacterial phyla in the rhizosphere soils were Proteobacteria,Actinobacteria,Acidobacteria,Chloroflexi and Firmicutes and Ascomycota were the dominant fungal phyla. There were 13 bacterial and 5 fungal phyla with significant difference in relative abundance between the north and south slopes of the four main producing areas. The difference of α diversity index of bacteria and fungi in the rhizosphere soils of the north and south slopes of the main producing areas of Dehong, Lincang and Baoshan was obvious. Principal coordinate analysis demonstrated that there were remarkable differences in the composition of bacterial and fungal communities in the rhizosphere soils of the four main producing areas. However,Anosim and Adonis analysis showed that there was no significant difference in the bacterial and fungal communities in the rhizosphere soil between north and south slopes at the same site(P>0.05). Redundancy analysis showed that pH was the primary environmental factor affecting the composition of the dominant bacterial and fungal phyla communities in the rhizosphere soil of C. arabica. 【Conclusion】In conclusion,the nutrient and α diversity of bacterial and fungal communities in the rhizosphere soil on the north slope are more abundant than those on the southern slope,which is more suitable for the cultivation of C. arabica.