连续施用生物有机肥对烟草青枯病的防治效果

分离获得一株对烟草青枯病病原菌茄科劳尔氏菌(Ralstonia solanacearum,简称RS)具有较强拮抗能力的拮抗菌(SQR11)并制成生物有机肥,研究了连续施用该生物有机肥对烟草青枯病的防治效果。结合生理生化和16SrDNA技术鉴定,菌株SQR11被鉴定为解淀粉芽孢杆菌。施用该生物有机肥后第一季烟草青枯病的生物防治率达到47%以上,第二季为69%以上,第三季达到89%以上。第三批盆栽实验表明,当根际土中病原菌数量达到2×105cfu/g干土时,植株出现发病症状,随着病原菌数量的增加,发病症状加重。当根际土中拮抗菌活菌数量达到2×107cfu/g干土时,病原菌繁殖得到有效抑制,可有效阻止植株染病;若低于107cfu/g干土,则不能有效抑制病原菌增殖,植株表现发病症状。植株各组织内拮抗菌数量检测发现,未发病植株茎部拮抗细菌数量为4×104cfu/g(组织鲜重,下同)左右,而同处理中发病症状的植株茎部拮抗细菌数量仅为6×103cfu/g;相对应的病原菌数量分别为1.5×102cfu/g(健康植株)和3×103cfu/g(发病植株)。SQR11菌株制成的生物有机肥还具有较好的促生作用。总之,利用拮抗菌SQR11菌株制成的生物有机肥对烟草青枯病具有显著的生物防治作用,在根部进行大量定殖后可有效防止病原菌的侵入,能够获得显著的生防效果。

Effects of Successive Application of Bioorganic Fertilizer on Controlling Tobacco Wilt Caused by Ralstonia solanacearum

An antagonistic bacterium named SQR11 which possessed strong ability to suppress tobacco bacterial wilt caused by Ralstonia solanacearum (abbreviated as RS) was isolated, and the biological control effect of successive application of bioorganic fertilizer produced by this strain on controlling tobacco wilt was studied. Based on physiological and biochemical determination and the 16S rDNA sequence analysis, strain SQR11 was identified as Bacillus amyloliquefaciens. Biological control efficiency of the bioorganic fertilizer applied during the successive batches of pot experiments were 47%, 69% and 89%, respectively. Results from the third pot experiment indicated that plants showed symptoms when the number of pathogens in the rhizosphere soil reached 2×105 cfu/g dry soil, and the incidence of symptoms were accompanied with the increasing number of RS. The pathogens were effectively controlled when the number of antagonistic bacteria in the rhizosphere soil reached 2×107 cfu/g dry soil. The number of the antagonistic bacteria in the stems of the healthy tobacco was 4×104 cfu/g plant tissue, while the number of the pathogens in the same position was 1.5×102 cfu/g plant tissue; the number of the antagonistic bacteria in the stems of the diseased tobacco was only 6×103 cfu/g plant tissue, whereas the number of the pathogens in the same position reached 3×103 cfu/g plant tissue. The results also indicated that application of the bioorganic fertilizer could also promote tobacco growth. In conclusion, successive application of bioorganic fertilizer produced by strain SQR11 could significantly control the tobacco bacterial wilt caused by Ralstonia solanacearum by extensive colonization of SQR11 in the tobacco roots.