连作对纹党根际土壤酶活性和微生物群落结构的影响

Effects of Continuous Cropping on Enzyme Activities and Microbial Community Structure in the Rhizosphere Soil of Codonopisis pilosula Nannf.var.modesta(Nannf.) L.T.Shen

    摘要
  • 摘要:
    目的 探究不同连作年限纹党根际土壤酶活性和微生物群落结构的变化及其关联性，为揭示纹党连作障碍的发生机制和土壤改良提供理论依据。
    方法 以三年内未种植过纹党的正茬土壤（CK）及纹党连作1年（C1）、2年（C2）和3年（C3）的根际土壤为研究对象，采用常规分析方法测定土壤酶活性，采用Illumina高通量测序技术测定土壤微生物群落结构和多样性，研究不同连作年限土壤酶活性及微生物群落结构的变化特性，探究微生物群落与土壤酶活性之间的关系。
    结果 随着连作年限的增加，纹党连作土壤中碱性磷酸酶和硝酸还原酶活性均显著增加，蔗糖酶和脲酶活性先升高后降低，过氧化氢酶活性先降低后升高。随着连作年限的增加，纹党根际土壤中细菌群落丰富度下降，多样性增加，变形菌门（Proteobacteria）、放线菌门（Actinobacteriota）等优势菌门及鞘氨醇单胞菌属（Sphingosinomonas）等有益类群相对丰度降低，连作1年、2年和3年时这些类群相对丰度较CK分别下降了5.64%、3.01%、10.66%，8.39%、2.95%、14.70%和16.90%、7.24%、22.48%，连作2年和3年时三个类群相对丰度较连作1年分别下降了2.91%、0.71%、4.52%和11.92%、4.35%、13.23%。土壤真菌群落丰富度和多样性均升高，子囊菌门(Ascomycota)、被孢霉门（Mortierellomycota）及被孢霉属（Mortierella）等优势类群相对丰度不断降低，C1、C2、C3处理较CK分别下降了16.05%、22.41%、23.56%，22.03%、3.60%、29.04%和29.51%、35.99%、32.35%，C2、C3处理子囊菌门相对丰度较C1分别下降了7.12%和16.04%，被孢霉门相对丰度C2较C1增加了24.24%，C3较C1下降了17.50%，C2和C3处理被孢霉属较C1分别下降了7.17%和11.50%。镰刀菌属（Fusarium）相对丰度较CK增加，C1、C2和C3较CK分别增加了1.49%、5.97%和8.96%，C2、C3较C1分别增加了4.41%和7.35%。相关性分析表明，碱性磷酸酶活性与Unclassified_f__Micrococcaceae属相对丰度呈极显著负相关（P < 0.01），与Norank_f__A4b和MND1属相对丰度呈显著负相关（P < 0.05）；蔗糖酶、脲酶与青霉菌属相对丰度均呈显著负相关（P < 0.05），碱性磷酸酶活性与被孢霉属及Paramyrothecium属相对丰度呈显著负相关（P < 0.05），蔗糖酶、脲酶及硝酸还原酶活性与赤霉菌属相对丰度均呈显著正相关（P < 0.05），碱式磷酸酶活性受到微生物群落结构变化的影响较大。
    结论 连作导致纹党土壤微生物群落结构失衡、土壤酶活性改变，微生态环境的恶化是纹党连作障碍发生的重要原因之一。

     

    Abstract:
    Objective The purpose of this study was to explore the changes and correlation of rhizosphere soil enzyme activities and microbial community structure in different continuous cropping years of Codonopisis pilosula Nannf.var.modesta(Nannf.) L.T.Shen, so as to provide theoretical basis for revealing the mechanism of continuous cropping obstacles and soil improvement.
    Method The normal soil (CK) that had not been planted in three years and the rhizosphere soil that had been continuously cultivated for 1 year (C1), 2 years (C2) and 3years (C3) were used as the research objects. The soil enzyme activities were determined with conventional analysis methods, and the soil microbial community structure and diversity were determined with Illumina high-throughput sequencing technology. The change characteristics of soil enzyme activities and microbial community structure in different continuous cropping years were studied to explore the relationship between microbial community and soil enzyme activities.
    Result The results showed that the activities of alkaline phosphatase and nitrate reductase in treatments of continuous cropping of C. pilosula Nannf.var.modesta(Nannf.) L.T.Shen increased significantly with the increase of continuous cropping years, while the activities of sucrase and urease increased first and then decreased, and the activities of catalase decreased first and then increased. As the consecutive planting years increased, the richness of bacterial community in the rhizosphere soil decreased, while diversity increased. The relative abundance of dominant bacterial phyla such as Proteobacteria and Actinobacteriota decreased, as well as beneficial groups (Sphingosinomonas). The relative abundance of these groups decreased by 5.64%, 3.01%, 10.66%, 8.39%, 2.95%, 14.70% and 16.90%, 7.24%, 22.48% compared with CK in 1, 2 and 3 continuous cropping years, respectively. The relative abundance of three groups decreased by 2.91%, 0.71%, 4.52% and 11.92%, 4.35%, 13.23% in 2 and 3 years compared with 1 year of continuous cropping, respectively. The richness and diversity of soil fungal communities increased. The relative abundance of dominant groups such as Ascomycota, Mortierellomycota and Mortierella decreased. C1, C2 and C3 treatments decreased by 16.05%, 22.41%, 23.56%, 22.03%, 3.60%, 29.04% and 29.51%, 35.99%, 32.35% compared with CK, respectively. The relative abundance of Ascomycta decreased by 7.12% and 16.04% compared with C1 in C2 and C3 treatments, respectively. The relative abundance of Mortierellomycota increased by 24.24% compared with C1 in C2 treatments, the relative abundance of Mortierellomycota decreased by 17.50% compared with C1 in C3 treatment, and the relative abundance of Mortierella decreased by 7.17% and 11.50% compared with C1 in C2 and C3 treatments, respectively. The relative abundance of Fusarium increased compared to CK, increased by 1.49%, 5.97% and 8.96% in C1, C2 and C3 treatments, and C2 and C3 treatments increased by 4.41% and 7.35% compared with C1, respectively. The correlation analysis showed that the activities of alkaline phosphatase were significantly negatively correlated with the relative abundance of Unclassified_f__Micrococcaceae genus（P < 0.01）, and were negatively correlated with the relative abundance of Norank_f__A4b and MND1 genus（P < 0.05). There was a significant negative correlation between sucrase and urease and Penicillium（P < 0.05）, a significant negative correlation between the activities of alkaline phosphatase and the relative abundance of Mortierella and Paramyrothecium（P < 0.05）, and a significant positive correlation between the activities of sucrase, urease and nitric reductase and the relative abundance of Gibberella（P < 0.05）. The activities of alkaline phosphatase were greatly affected by the changes of microbial community structure.
    Conclusion Continuous cropping results in the imbalance of soil microbial community structure and the change of soil enzyme activities. The deterioration of microecological environment is one of the important reasons for the occurrence of continuous cropping obstacles of C. pilosula Nannf.var.modesta(Nannf.) L.T.Shen.

     

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