不同种植模式对青稞根际土壤微生物群落结构的影响

采用Illumina MiSeq高通量测序技术,对6种种植模式下青稞根际土壤的16S rDNA和18S rDNA基因相关区片段进行测序,研究根际土壤细、真菌群落结构的变化,并结合土壤理化性质,分析环境因子与群落结构的关系,从根际土壤微生物生态系统的角度解析青稞连作障碍的发生机制。6种种植模式中,土壤有机质和全氮含量WHD模式最高,全磷含量YC模式最高,全钾含量MLS模式最高,pH均为碱性;3种连作模式下,随着连作年限的增长,土壤有机质、全氮和全钾逐年降低,全磷显著升高。6种种植模式下,细菌和真菌群落Alpha多样性指数和覆盖度没有显著差异,与连作相比,WHD和MLS模式可显著提高细菌群落的Shannon指数、ACE指数和Chao1指数;与混作、轮作相比,连作显著提高真菌群落的Shannon指数和ACE指数,但Chao1指数差异不显著;连作使细菌群落Alpha多样性减小,真菌群落Alpha多样性增加。6种种植模式下,genus水平群落结构表现为连作使青稞根际土壤中微生物区系发生较大改变,导致有害菌群丰度增加,有益菌群数量减少,尤其是真菌菌群发生较大改变,而轮、混作模式使优势菌群及新种数量明显增加。细菌、真菌群落PCoA分析结果表明,微生物群落在6种种植模式间变异较小且未发生明显分化,PC1、PC2的总解释能力均大于80%,表明有显著主导因子。细菌、真菌群落与土壤理化性质关系显示,土壤有机质、全氮与提高WDH、QKA模式下的细菌群落多样性呈正相关,而pH、有机质、全氮与提高WDH、YC、QKB模式下的真菌群落多样性呈正相关。表明,与连作相比,WDH和MLS模式可改善土壤理化性质,提高根际细菌群落结构多样性及微生物群落组成,是缓解青稞连作障碍的可能途径,可为青稞连作障碍修复措施的制定提供科学依据。

Effects of Different Cropping Modes on Microbial Community Structure in Rhizosphere Soil of Hulless Barley

Illumina MiSeq high-throughput 16S rDNA and18S rDNA sequencing technology were used to study the bacterial and fungal community structure in rhizosphere soil. In addition, the relationship between environmental factors and community structure was analyzed with combination with soil physical and chemical properties, the the occurrence mechanism of continuous cropping obstacles of hulless barley was analyzed from the perspective of rhizosphere soil microbial ecosystem.Under the six cropping modes, soil organic matter, total nitrogen content (WHD), total phosphorus content (YC) and total potassium content (MLS) were the highest, and soil was all alkaline. Under the three continuous cropping modes, soil organic matter, total nitrogen and total potassium decreased and total phosphorus increased with the increase of continuous cropping years. Under the six cropping modes, the Alpha diversity index of bacterial and fungal communities showed no significant difference in coverage. Compared with continuous cropping, WHD and MLS could significantly improve Shannon index, ACE index and Chao1 index of bacterial communities. Compared with mixed cropping and rotation cropping, continuous cropping significantly improved the Shannon index and ACE index of fungal communities, but Chao1 index had no obvious difference. The continuous cropping reduced the Alpha diversity of bacterial community and increased the Alpha diversity of fungal community. Under the six cropping modes, the community structure of the level genus could be shown as follows:continuous cropping could cause great changes in the microbial flora of the hulless barley rhizosphere soil, and could increase the abundance of harmful bacteria and reduce the number of beneficial bacteria, especially affect the fungal flora, while rotation and mixed cropping mode could significantly increase the number of dominant bacteria and new species. PCoA analysis of the bacterial and fungal communities showed that the microbial communities had little variation and no obvious differentiation among the six cropping modes, and the total explanatory ability of PC1 and PC2 was more than 80%, indicating that there were significant dominant factors. The results showed that soil organic matter and total nitrogen were positively correlated with the increase of bacterial community diversity under WDH and QKA modes, while pH, organic matter and total nitrogen were positively correlated with the increase of fungal community diversity under WDH, YC and QKB modes. This study showed that, compared with continuous cropping, WDH and MLS could improve soil physical and chemical properties, increase the diversity of rhizosphere bacterial community structure and microbial community composition, so it is a possible way to alleviate the obstacles of continuous cropping of hulless barley, which can provide scientific basis for the measures to repaire the obstacles of continuous cropping of hulless barley.