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在微生物３大类群中，细菌总数在整个大豆生育期内占绝对优势，重茬低于正茬，花期、结荚期尤为明显；放线菌数量总体变幅不大，花期、成熟期重茬高于正茬，而苗期则相反；真菌数量变化很大，重茬高于正茬，花期最为显著。在连作大豆根际土壤中，有益真菌减少，有害真菌增加。将真菌优势菌群中的尖镰孢菌、半裸镰孢菌和粉红粘帚菌回接大豆，均产生不同程度的致病性，导致大豆根腐病的发生，花期前后（３８～５０ｄ）病症明显。３菌株毒素粗提物对大豆毒害性试验结果表明：大豆发芽率显著降低，植株生长受阻。
In the three groups of microorganisms, the total number of bacteria in the whole growth stage of the soybean accounted for the absolute advantage, stubble is lower than the stubble, florescence, podding period is particularly evident; Actinomycetes overall amplitude is not large, flowering, mature stubble higher than While the seedling stage is the opposite. The number of fungi varies greatly, and the stubble is higher than the stubble, and the florescence is the most significant. In continuous crop rhizosphere soils, beneficial fungi are reduced and harmful fungi are increased. Fusarium oxysporum, Fusarium solani and pink viscera back to soybeans in the dominant flora of the fungi all had different pathogenicity, which led to the occurrence of soybean root rot, the disease of 38-50 days before flowering obvious. 3 strains of toxins crude extracts on soybean poisoning test results show that: soybean germination rate was significantly reduced, plant growth retardation.