| Astragalus membranaceus(Fisch.)Bge.var.mongholicus(Bge.)Hsiao is a perennial herb of the genus Astragalus in the family Fabaceae.It is a traditional Chinese herbal medicine for replenishing qi and has high medicinal value.Scientific fertilization technique is an important factor affecting the quality and yield of Astragalus membranaceus.Compared with conventional soil fertilization,foliar fertilization has the characteristics of low dosage and obvious effect.As an important communication medium between plants and soil,soil microorganisms play an important role in plant growth.Fertilizers can change the composition of the soil microbial community to a great extent.Reasonable fertilizer application can promote the growth of Astragalus membranaceus by providing appropriate nutrients and regulating the rhizosphere microbial community.In this study,the planting bases of Astragalus membranaceus in Chifeng City and Baotou City,Inner Mongolia were selected,the rhizosphere soil of Astragalus membranaceus after spraying different foliar fertilizers was collected as samples.The community structure and functional diversity of rhizosphere microorganisms were evaluated by Illumina Nova Seq high-throughput sequencing and BIOLOG Eco microplate method,the physical and chemical properties and enzyme activities of relevant soils were measured.To explore the changes in microbial community and functional diversity in the rhizosphere of Astragalus membranaceus under the regulation of different nutrient elements,to provide the basis for standardized planting of Astragalus membranaceus.The following were the main points:1.The results of high-throughput sequencing showed that there were 15 phyla,54 classes,125 orders,267 families,and 449 genera of rhizosphere soil fungi of Astragalus membranaceus.,It mainly includes Dothideomycetes(25.82 % ～ 54.96 %),Sordariomycetes(19.63 % ～38.27 %),Mortierellomycetes(3.69 % ～ 11.36 %),Agaricomycetes(0.73 % ～ 8.48 %),Tremellomycetes(1.63 % ～ 2.69 %).The diversity and richness of soil fungal communities can be significantly improved by spraying macroelement and total elemental foliar fertilizers.The treatment of total elements and trace elements foliar fertilizer can cause significant changes in the structure of soil fungal community.In the treatment of total element foliar fertilizer,Sordariales and Mortierellomycetes are the groups that cause significant differences in the community structure of soil fungi.In the treatment of foliar fertilizer with trace elements,Sordariomycetes,Eurotiomycetes and Alternaria were the groups that caused significant differences in the community structure of soil fungi.After spraying macroelement foliar fertilizer,the longest average path length and the densest network map density were found in the soil fungal network,and the network structure of the fungal community was more complicated.2.The results of high-throughput sequencing showed that there were 57 phyla,91 classes,209 orders,392 families,and 783 genera of soil bacteria of Astragalus membranaceus.It mainly includes Actinobacteria(13.91 % ～ 25.65 %),Gammaproteobacteria(10.65 % ～ 17.12 %),Alphaproteobacteria(13.25 % ～ 19.24 %),Bacteroidia(8.13 % ～ 15.00 %),Bacillus(2.69 % ～6.53 %).The soil bacterial communities treated with macroelement and total element foliar fertilizer had uniform distribution and high community diversity.The treatment of foliar fertilizer with macroelement can cause obvious changes in the structure of soil bacterial community,Solirubrobacterales,Rhizobiales and Nitrospirales are the groups that cause significant differences in the bacterial community structure of rhizosphere soil.The average network connectivity,network graph density,and clustering coefficient of soil bacteria treated with trace element foliar fertilizer increased,which could enhance the connection between soil bacteria.3.The application of foliar fertilizer with different nutrient elements had significant effects on the functional diversity of the soil microbial community.Microorganisms had the highest utilization rate of amino acids and carbohydrates among the six types of carbon sources.,while phenolic acids and amines had the lowest utilization rate.Trace elements can increase the uniformity and diversity of carbon source metabolism in soil microbial community,and improved the functional diversity of soil microbial.4.There were significant differences in most soil factors between different sites and foliar fertilizer treatments,and the soil factors were closely related.The sample plots and foliar fertilizer treatment could significantly affect the soil factor and enzyme activities,among which the effect on the soil available potassium was the greatest.The soil p H,available potassium,and urease activity in the two places were the main soil factors that caused the difference in soil fungal and bacterial community structure.Soil factors had a great impact on soil fungal diversity,while foliar fertilizer treatment had a great impact on soil bacterial diversity.Both soil factors and foliar fertilizer treatment had an impact on the functional diversity of the soil microbial community,and soil factors had a greater influence.Among them,carboxylic acids and amino acids were significantly positively correlated with organic carbon and available nitrogen,amines,and phenolic acids were significantly positively correlated with urease activity,and soil temperature was significantly negatively correlated with carboxylic acids. |
