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磷脂脂肪酸方法(PLFA)可较准确地表达土壤微生物的类群及其生物量,是一种快速、重现性好的分析土壤微生物群落结构多样性方法。以中国科学院海伦农业生态试验站定位试验区大豆20年连作、轮作、迎茬和裸地的耕层土壤为对象,采用PLFA方法在大豆盛花期、鼓粒期和成熟期对不同轮作方式下土壤微生物群落结构进行研究。结果表明:20年连作使土壤微生物总磷脂脂肪酸含量有所增加,尤其是在盛花期,20年连作微生物总磷脂脂肪酸(PLFA)含量为10 327μg·g-1,显著高于其它轮作方式,20年轮作和迎茬土壤微生物总磷脂脂肪酸含量在大豆3个生育时期变化并不显著。土壤中真菌、细菌和放线菌PLFA含量与总PLFA含量变化基本一致。但是轮作条件下细菌/真菌磷脂脂肪酸比值显著高于其它轮作方式,说明轮作增加了土壤细菌PLFA含量,降低了真菌PLFA含量。对主要PLFAs进行主成分分析,主成分一(PC1)解释了45.5%的变异,主成分二(PC2)解释了20.6%的变异,而且从主成分得分图上可明显将轮作和迎茬与连作和裸地区分开。结果说明20年连作在一定程度上改变了土壤微生物群落结构,但20年轮作土壤生态系统仍然相对较稳定。
Phospholipid fatty acid method (PLFA) is a rapid and reproducible method to analyze the diversity of soil microbial community structure, because it can express the soil microbial flora and its biomass more accurately. The soil samples of topsoil crop continuous cropping, rotation, stubble and bare land in 20-year-old trial of soybean in Helan Agro-Ecological Experimental Station of Chinese Academy of Sciences were used as experimental objects. The soil samples from full bloom, Microbial community structure research. The results showed that the content of total phospholipid fatty acids in soil microorganisms increased with continuous cropping for 20 years. Especially in full flowering stage, the content of total phospholipid fatty acids (PLFA) in continuous cropping soil was 10 327 μg · g-1 in 20 years, which was significantly higher than that in other crop rotation patterns. The contents of total phospholipid fatty acids in soil microbial biomass during the three growth stages of soybean were not significantly different. PLFA contents of fungi, bacteria and actinomycetes in soil are basically the same as those of total PLFA. However, the ratio of bacterial / fungal phospholipid fatty acids under rotation was significantly higher than that of other rotation patterns, indicating that rotation increased PLFA content of soil bacteria and decreased fungal PLFA content. The principal component analysis (PC1) explained 45.5% of the major PLFAs. The principal component (PC2) explained 20.6% of the variation, and from the principal components score, And naked areas are separated. The results showed that continuous cropping for 20 years changed soil microbial community structure to some extent, but the 20-year rotation of soil ecosystem was still relatively stable.