Purpose To study the regulatory ability of cultivation systems on soil microbial communities, laying the foundation for reasonable arrangement of cultivation systems.
Methods A pot experiment was conducted under four different conditions (soil autoclaving and fertilization, soil autoclaving with fertilizer-free, soil autoclaving-free and fertilization, and soil autoclaving-free and fertilizer-free) with potato continuous cropping (CC) system as control. Amplification and sequencing of the V3-V4 region of bacterial 16S rRNA gene in soil samples from crop root zone in rice-potato rotation (RC) and CC systems by PCR, the species composition, diversity, functional composition and ecological network of bacterial community were compared.
Results RC significantly affected soil bacterial community structure. Under autoclaving-free condition, the bacterial community richness index of RC soil with fertilization and fertilizer-free significantly increased 15.62% and 9.05%, respectively; the Shannon diversity index significantly increased 2.45% and 1.71%, respectively; but the species diversity and abundance of bacterial community in CC soil did not change significantly. Under autoclaving condition, the richness and Shannon diversity index of soil bacterial communities in the RC system increased to the level of before autoclaving; the Shannon diversity index of soil bacterial community in the CC system was significantly decreased, and the richness only recovered to the level of before autoclaving merely under the fertilization condition. Analysis of soil bacterial functional composition differences between the RC and CC system showed that: RC could significantly increase the abundance of 13 types of soil bacteria, while CC could only increase the abundance of four types of soil bacteria, including bacteria concerning chitinolysis and plant pathogens. Compared with CC, betweenness centrality, edges number, graph density, nodes number, average degree, graph diameter, modularity and average path length of soil bacteria network increased by 10.00 times, 2.50 times, 2.40 times, 1.10 times, 0.64 times, 0.63 times, 0.55 times and 0.40 times, respectively; however, betweenness centrality, graph density, edges number, average degree, nodes number and degree centrality of the ecological network of bacterial pathogen population decreased by 71.4% , 67.7% , 50.9% , 36.1% , 23.2% and 11.1% , respectively. In addition, the topological features of network of the pathogenic genera were also significantly reduced in winter potato cultivated soils compared to summer cultivated soils.
Conclusion RC can significantly enhance the species and functional diversity of soil bacterial communities, and regulate species interaction among soil bacterial community, exerting a significant regulatory effect on soil bacterial communities.
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