桑树间作大豆对桑园土壤微生物多样性的影响

Impact of Intercropping Soybean in Mulberry Field on Soil Microbial Diversity

利用稀释平板法与Biolog-Eco技术对桑树单作、桑树-大豆间作的桑园土壤微生物数量、种群结构以及微生物碳代谢多样性进行研究,为桑树合理间作其它作物改良桑园土壤提供理论依据。桑树间作大豆的桑园,桑树根际(IMR)土壤中的细菌和放线菌数量、可培养细菌种群结构、微生物碳代谢活性的平均单孔颜色变化率(AWCD)及多样性指数(H)均显著高于单作桑园,而真菌数量低于单作桑园。争论贪噬菌(Variovorax paradoxus)和沙福芽孢杆菌(Bacillus safensis)是间作桑园的桑树根际土壤中特有的优势菌属。土壤微生物对不同碳源的利用及主成分分析表明,糖类、氨基酸、聚合物和混合物是间作桑园桑树根际土壤微生物利用的主要碳源类型,利用强度均显著高于单作桑园的桑树根际土壤微生物。间作桑园土壤的有机质、速效磷和速效钾含量亦显著高于单作桑园。以上研究结果表明,桑树间作大豆改变了桑树根际土壤微生物群落结构组成,增强了根际土壤微生物群落的碳代谢多样性,改善了土壤养分条件。

The microbial quantity, community structure and functional diversity of carbon metabolism between mulberry monocropping and mulberry-soybean intercropping were investigated using dilution-plate method and Biolog-Eco tech- nology to provide theoretical basis for improving the quality of mulberry field soil through rational intercropping mulberry with other crops. The results indicated that bacterial and actinomyce quantity, culturable bacteria community, average well color development （AWCD） of carbon metabolism and Shannon diversity index （H） in rhizospheric soil of inter- cropped mulberry field were significantly higher than those of monocropped mulberry field, while the quantity of fungi in intercropped mulberry filed was lower than that of monocropped mulberry field. Variovorax paradoxus and Bacillus safen- sis were the special dominant bacteria in rhizospheric soil of intercropped mulberry field. Utilization of different types of carbon source by microbes and the principle component analysis indicated that carbohydrate, amino acid, polymers and mixture were the main carbon sources utilized by microbes in rhizospheric soil of intercropped mulberry field, and the uti- lization ability of these carbon sources were all significantly higher than that in monocropped mulberry field. The contents of organic matter, available phosphorus and available potassium in intercropped mulberry field were significantly higher than those in monocropped mulberry field. The above results indicated that mulberry and soybean inter- cropping could change the microbial community in rhizos- pheric soil, promote carbon metabolism diversity of rhizo- spheric microbial colonies, and improve soil nutritional condition.