| Areca nut is an important pillar industry in Hainan Province,and the yellowing of areca nut leads to the decline of its yield and quality,which seriously affects the development of areca nut industry in Hainan Province.Earthworm manure plays an important role in improving soil physical structure and improving soil fertility.In this study,the distribution characteristics of microbial diversity in betel nut rhizosphere soil in different betel nut planting areas(Wanning,Lingshui and Sanya)were dynamically analyzed by using Illumina Miseq high-throughput sequencing,and the correlation between soil physical and chemical properties and microbial community distribution was revealed Taking the betel nut planting area in Wanning as the research object,the effects of earthworm cast on microbial diversity in betel nut rhizosphere soil were studied,and the correlation between soil physical and chemical properties and microbial community structure was revealed,so as to provide scientific basis for improving soil by earthworm cast.The main results of this study are as follows:(1)There are differences in soil physical and chemical properties at sampling points in different betel nut planting areas,among which pH and organic matter content at Wanning sampling point are obviously lower than those at other two sampling points;The contents of total potassium and available potassium in Lingshui sampling site are higher than those in other two sampling sites.However,the content of available phosphorus was the highest in Sanya sampling site.(2)The microbial community diversity of Areca catechu rhizosphere soil at different sites was measured by high-throughput sequencing method.The results showed that there were spatial differences in microbial diversity at different sampling sites.A total of 4989 operational taxonomic units(OTU)belonging to 33 phyla and 770 genera were obtained from three sampling sites,among which the dominant phyla were Proteobacteria and Acidobacteria,accounting for 67.60%～91.29% and 1.30%～9.24%respectively.Among them,the bacterial diversity in Lingshui sampling site(Shannon index: 3.11)was higher than that in Wanning(2.41)and Sanya sampling site(2.07),and there was significant difference among the three sampling sites(P<0.05).A total of 2078 fungal classification operating units were obtained from three sampling sites,belonging to 18 phyla and 381 genera,among which the dominant phyla was Ascomycota,and its abundance accounted for 76.31%～94.58%.The diversity of fungi in Lingshui sampling site(3.34)is higher than that in Wanning(3.04)and Sanya sampling site(2.32).(3)Network interaction analysis and redundancy analysis show that the interaction relationship of microbial community structure between different sites shows some differences.Environmental factors have great influence on the composition of bacterial community,and the correlation between different points and environmental factors is different.The most closely related genera of bacteria in the three sampling sites are Occallatibacter of Acinobacteria,G＿NORRANK＿C＿AD3 of Chloroflexi of Lingshui sampling site,Candidatus Solibacter of Acidophila of Sanya area.The genera with the strongest correlation among the three sampling sites are Talaromyces of Ascomycota,an unnamed genus and g＿unclassified＿o＿Branch06.(4)After the application of earthworm cast,the soil physical and chemical properties of betel nut land were affected,and the soil pH and organic matter content increased significantly.The microbial diversity of soil rhizosphere also changed,and the dominant flora showed structural differences.The abundance of Proteobacteria and Actinobacteria increased by 19.31% and 14.01% respectively.The abundance of fungi Ascomycota and Basidiomycota increased by 45.93% and 7.03% respectively.(5)According to the analysis of network interaction,Acidothermus of Actinobacteria has the strongest correlation with other species in bacteria,and Roussoella of Ascomycota and Saitozyma of Basidiomycota have the strongest correlation with other species in fungi.(6)The correlation analysis of microbial community structure and physical and chemical properties of Areca catechu rhizosphere soil after applying earthworm cast showed that there was a certain correlation between environmental factors and microbial community structure,and the difference between groups of microbial community structure after applying earthworm cast was greater than that within groups,which indicated that earthworm cast had certain influence on the microbial community structure of rhizosphere soil.Among them,the dominant flora Proteobacteria was positively correlated with pH,organic matter and other physical and chemical factors,while Ascomycetes was positively correlated with available potassium.The results indicated that the increase of pH and organic matter after applying earthworm cast increased the abundance of Proteobacteria,which promoted the decomposition or absorption of organic matter,improved the soil environment and was more conducive to the survival of beneficial microorganisms.Innovations:1.The diversity of rhizosphere microorganisms in Areca catechu soil from different locations in Hainan was compared and analyzed.2.The correlation between soil microbial diversity and physicochemical properties of Areca catechu was revealed.3.It was clarified for the first time that earthworm cast can affect the microbial community structure in Areca catechu rhizosphere,which provided a new basis for analyzing the mechanism of improving soil by earthworm cast. |
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