Abstract:

To investigate whether earthworm castings can affect the bacterial diversity of maize soil inside and outside the facility,so as to provide a reference for studying the difference in soil ecological quality between earthworm castings inside and outside the facility at the microbial level.Based on Illumina NovaSeq sequencing platform,16S rRNA sequencing was performed on rhizosphere soil bacteria of maize in different planting modes(different varieties of maize in and outside earthworm manure facilities and different varieties of maize in and outside conventional facilities).A total of 35 627 operational taxonomic units(OTUs)were obtained after quality control,with a total of 1 832 428 valid sequences.The OTU number of soil samples,bacterial community structure,relative abundance,the difference between dominant bacteria genera and groups,and the difference in bacterial diversity analysis were compared under different planting patterns.The OTU number of soil samples was significantly different between earthworm droppings and conventional planting mode.The OTU number of earthworm droppings was higher than that of conventional planting,but the difference was not significant between earthworm droppings and different maize varieties.The dominant microphyla of soil community structure were basically the same,but there was a large difference in the abundance of microphyla between inside and outside the facility and whether or not earthworm castings were applied,and there was little difference between different maize varieties.At the phylum level,the relative abundance of Proteobacteria and Bacteria in and outside conventional planting facilities(class D)was higher than that in and outside vermicomical planting facilities(class E),while the relative abundance of Actinobacteria and Blastomonas in and outside conventional planting facilities(class E)was higher than that in and outside conventional planting facilities(class D).At the generic level,Sphingomonas,Unclassified_Gemmatimonadaceae,Subgroup_10,Unclassified_Bacteria and Unclassified_Vicinamibacteraceae were found to be more abundant in worm castings than in conventional ones.While Unclassified_Microscillaceae,Altererythrobacter,Flavobacterium,Unclassified_Vicinamibacteraceae and Uncultured_gamma_proteobacterium,these five genus had a higher abundance in conventional cultivation than in vermicompost cultivation.The results of diversity analysis showed that the Chao1,Ace,Shannon and Simpson indices of earthworm manure planting(type E)were significantly higher than those of conventional planting(type D).The number and diversity of soil bacteria in earthworm manure planting mode were higher than those in conventional planting mode,and different planting modes significantly affected the composition of soil bacterial community.

Key words: Facility cultivation, Soil bacteria, Community structure, Diversity, High-throughput sequencing