水稻—马铃薯轮作对盆栽土壤细菌群落结构的影响

Effects of Rice-Potato Rotation on Soil Bacterial Community in Pot Experiment

【目的】研究耕作系统对土壤微生物群落的调节能力,为合理布局耕作系统奠定基础。【方法】以马铃薯连作为对照种植系统,在4种条件下(土壤灭菌加施肥、土壤灭菌不施肥、土壤不灭菌加施肥、土壤不灭菌不施肥)设计盆栽试验。通过PCR技术扩增并测序水稻—马铃薯轮作(以下简称“稻薯轮作”)和马铃薯连作系统中每个种植季节作物根区土壤样本的细菌16S rRNA基因的V3~V4区域,并比较细菌群落的物种组成、多样性、功能组成和生态网络。【结果】稻薯轮作可显著影响土壤细菌群落结构。在未灭菌条件下,轮作施肥和未施肥土壤的细菌群落丰富度指数分别显著提高15.62%和9.05%,香农多样性指数分别显著提高2.45%和1.71%;而连作土壤细菌群落的物种多样性和丰富度无显著变化。在土壤灭菌后,稻薯轮作土壤细菌群落物种的丰富度指数和香农多样性指数可提高到灭菌前水平;而连作土壤细菌群落物种的香农多样性指数显著降低,丰富度仅在施肥时恢复到土壤灭菌前水平。稻薯轮作和马铃薯连作土壤细菌群落功能组成差异分析表明:稻薯轮作可显著提高13类土壤功能菌群的丰度;而连作仅能提高4类土壤功能菌群的丰度,其中包括几丁质分解菌和植物病原菌。与连作相比,轮作土壤细菌群落生态网络的介数中心性、边数、图密度、节点数、平均度、图径、模块性和平均路径长度分别提高了10.00倍、2.50倍、2.40倍、1.10倍、0.64倍、0.63倍、0.55倍和0.40倍;而细菌病原菌属群体生态网络的介数中心性、图密度、边数、平均度、节点数和度中心性分别降低了71.4%、67.7%、50.9%、36.1%、23.2%和11.1%。此外,冬季马铃薯种植土壤的病原菌属群体物种的生态网络拓扑特征参数也较夏季耕作土壤显著降低。【结论】稻薯轮作可显著提高土壤细菌群落的物种和功能多样性及调控土壤细菌群落物种的相互作用,对土壤细菌群落具有显著的调节作用。

[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 ricepotato 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% and9.05%,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 by10.00 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 by71.4%,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.