当归不同生长时期根际丛枝真菌分布及土壤养分和酶活性的动态变化

【目的】探讨当归不同生长时期丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)的分布及土壤养分和土壤酶活的变化,以期了解当归不同生长时期AMF与土壤养分和土壤酶活的关系,为AMF在当归种植的应用提供理论依据。【方法】在当归不同生长时期分别采集根际土壤样品,测定其土壤养分、土壤酶活、AMF孢子密度和球囊霉素等因子,分析当归不同生长时期根际土壤AMF孢子密度、土壤养分和土壤酶活等指标的动态变化和相关性。【结果】随着当归生育期的完成,根际土壤AMF孢子密度先降低后持续升高;易提取球囊霉素(Easily extractable glomalin,EEG)和总球囊霉素(Total glomalin,TG)平稳增加,而且EET与TG和脲酶活性呈显著正相关(P0.01),EET和TG与根际土壤有机质和全氮含量以及酸性和中性磷酸酶活性均显著正相关(P0.05);根际土壤有机质和全氮表现为增加的总趋势;有效磷含量呈现为生长前期保持不变、中期显著降低、后期逐渐升高的趋势,而有效钾含量先逐渐增加,生长中后期显著降低的趋势;根际土壤酸性和中性磷酸酶活性均呈现逐渐增加趋势,而脲酶活性表现为生长前期逐渐增加,中后期显著降低;p H值在当归不同生长时期有所波动。相关性分析结果表明,AMF孢子密度与土壤酸性磷酸酶酶活性呈显著正相关,而酸性磷酸酶酶活性与根际土壤全氮、有机质、易提取球囊霉素和总球囊霉素呈显著正相关,与有效磷和有效钾含量呈显著负相关,表明AMF对根际土壤养分和酶活性具有一定的调节作用;主成分分析结果表明,不同生长时期是影响当归根际土壤理化指标的主要因素。【结论】AMF孢子密度在当归根际的动态变化一定程度上反映出了AMF分泌球囊霉素的能力,以及球囊霉素对增加根际土壤碳氮储存的贡献,同时表明球囊霉素影响了当归根际土壤酶活性和其它养分的代谢循环,对改良土壤和促进当归生长发挥重要的作用。

Dynamics of arbuscular mycorrhizal fungi distributions, soil nutrients and enzyme activities in rhizosphere soil at different growth stages of Angelica sinensis

Objective] In order to understand the relationships between arbuscular mycorrhizal fungi (AMF) and soil nutrients and soil enzyme activities in Angelica sinensis field, the AMF spore densities, soil nutrient and soil enzyme activities of rhizosphere soil were investigated at its different growing stages. The results will provide a theoretical basis for the application of AMF in A. sinensis production. Methods] Rhizosphere soil samples were taken at different growing stages of A. sinensis. The rhizosphere soil nutrients, soil enzyme activities, AMF spore densities, and glomalin were measured and the correlative analysis and principal component analysis (PCA) were also conducted based on the measurements for further understanding the dynamic metabolism. Results] With the completion of the A. sinensis growth period, the AMF spore density of its rhizosphere soil decreased at early growth stages and then increased continuously in the following growth stages. And the easy extractable glomalin (EEG) and total glomalin (TG) had significant positive correlation with soil organic matter, total nitrogen, acid and neutral phosphatase activities (P<0.01), and the contents of EEG and TG in rhizosphere soil were significantly increased with A. sinensis growth (P<0.05). Soil organic matter and total nitrogen also show an increasing trend with A. sinensis growth. The available phosphorus content remained constant during the early growth stages, decreased significantly at the middle stage and gradually increased at the later stage, while the available potassium content increased significantly at the first and middle growth stages and decreased at late growth stages. Acidity and neutral phosphatase activities of rhizosphere soil increased gradually, while urease activity increased at the early growth stage, and decreased significantly in the middle and later stages. pH value fluctuated during different growth stages of A. sinensis. The correlation analysis shows that AMF spore density is significantly positively correlated with acid phosphatase activity, while the acid phosphatase activity significantly positively correlated with total nitrogen, organic matter, EEG and TG in rhizosphere soil, but significantly negative correlation between available phosphorus and available potassium, indicating that AMF could affect rhizosphere soil nutrients and enzyme activities. The correlative analysis refracts the relationships among the indexes. In particular, the PCA shows that the A. sinensis growth stage is the main factor for affecting the physical and chemical indexes of rhizosphere soil. Conclusion] The AMF spore densities at the rhizosphere of A. sinensis mainly reflect the ability of AMF to secrete glomalin and its contribution to the storage of carbon and nitrogen in rhizosphere soil, and the glomalin also affects the soil enzyme activities and nutrients metabolic cycle, and plays an important role in improving the soil quality and promoting the growth of A. sinensis.