野生大豆根际微生物的分离及其缓解大豆连作障碍的研究

利用唯一碳源培养基筛选野生大豆根际微生物,分离获得5株分别降解邻苯二甲酸、丙二酸、乙酸、丙酸、苯等大豆化感物质的微生物,分别命名为HK14-2、HK26-2、HN31-1、HK46-2、HK53-1.通过单菌落培养、显微镜观察、革兰氏染色以及PCR-DGGE电泳试验证明,筛选的5种微生物均为细菌,HK26-2为杆菌,其余为球菌,且均为纯系.菌落平皿对峙试验证明5种细菌均可拮抗大豆立枯丝核菌;不同菌剂的大豆盆栽试验证明5种细菌均可降低大豆根腐病发生率,其中HN31-1与HK53-1复配菌剂的防效高达69.5%.统计根系的主根长以及根干重的数据表明:筛选菌剂的添加增加了大豆的主根长以及根干重,改善大豆根际微生态环境.初步认为所分离野生大豆根际细菌可以缓解大豆连作障碍.

ISOLATION OF BACTERIA IN WILD SOYBEAN RHIZOSPHERE AND STUDY ON ITS FUNCTION TO REDUCE DISADVANTAGE OF SOYBEAN CONTINUOUS CROPPING

Five bacterial strains were isolated from wild soybean rhizosphere soil in medium contained only one kind of carbonaceous organic compound.They could digest phthalate,malonic acid,acetic acid,propionic acid and benzene and were named HK14-2,HK26-2,HN31-1,HK46-2 and HK53-1,respectively.Through single colony culture,microscope observe,Gram's dying and PCR-DGGE electrophoresis,it was showed that all of the screened five microbe were bacteria,HK26-2 was bacillus and others were coccus,and the isolated bacteria strain was pure.Test of colony standoff in dish proved the five bacteria could resist soybean pathogenic fungi(Rhizoctonia.solani).Potted soybean treated with different bacteria showed that the five bacteria could decrease the occurrence of soybean root rot,and the highest control effectiveness was 69.5% with compound bacteria of HN31-1 and HK53-1.Compared with the control,statistical data of taproot length and root dry weight showed that use of screened bacteria increased the numerical value and improved the environment of soybean rhizosphere.It was considered that the isolated bacteria from wild soybean rhizosphere could have biological control efficacy against pathogens of soybean root rot.