Study on the mechanism of bio-organic fertilizer controlling potato bacterial wilt | 生物有机肥防治马铃薯青枯病的机制研究

Chinese. 从马铃薯青枯病发病严重地块的健康植株根系分离到1株有效抑制马铃薯青枯菌的芽孢杆菌菌株，命名为T3。采用盆栽试验，分别通过对马铃薯植株病情指数的调查、平板计数和PCR―DGGE方法研究菌株T3发酵的生物有机肥对马铃薯青枯病的防治效果、根际微生物的数量及微生物群落结构的影响。结果表明：与化肥对照（CK）相比，1、3菌株发酵制成的生物有机肥（BF）显示m了对马铃薯青枯病的极显著防效，防治率为79．44％，而单独使用n菌液（T3）和有机肥（OF）的防治效果分别为27．10％和30．84％。各处理中马铃薯根际土壤的细菌数量均随时间表现IqI先增高后降低的趋势，在结薯期达到最高值。BF处理中，T3菌可有效在马铃薯根际定殖，并显著抑制病原菌的数量，而单独使用T3菌液及OF处理对病原菌数量的抑制作用不显著。马铃薯根系的细菌多样性分析表明，与cK相比，3个处理均能在一定程度上增加细菌群落多样性，其中BF处理对其多样性的提高最为明显，在幼苗期、发棵期、结薯期、成熟期和收获期，分别提高12．80％、10．17％、14．15％、5．17％和9．49％。结论：施用生物有机肥防治马铃薯青枯病主要是通过拮抗菌的大量定殖来抑制土壤青枯菌的增长和影响马铃薯根系微生物区系来实现的。

English. Bacillus strain T3 which was isolated from the roots of a healthy potato plant in a potato field destroyed seriously by bacterial wilt could effectively inhibit the potato bacterial wilt pathogen Ralstonia solanacearum. A pot experiment was designed to study the biocontrol effect of bio-organic fertilizer（ fermented by T3 ） , quantities of different kinds of microbes and the microbial flora of potato rhizosphere by investigation on potato disease severity index, plating count and PCR-DGGE methods respectively. Results showed that compared with the chemical fertilizer control（ C K）, the bio-organic fertilizer fermented by T3 （BF）showed extremely sig- nificant control effect on potato bacterial wilt with a biocontrol rate of 79.44% , and the biocontrol rates of treatments T3 and organic fertilizer（OF） were 27.10% and 30.84% , respectively. Results showed that the cultured bacteria numbers of the four treatments all increased gradually until tuber formation stage and then decreased till harvest time. In treatment BF, strain T3 could get a large number of colonization in potato rhizosphere soil, and significantly inhibit the growth of pathogen R. solanacearum, while treatments T3 and OF couldn＇t inhibit the number of pathogen effectively. The results of bacterial community diversities analysis performed by PCR-DGGE of bacterial 16S rRNA gene showed that compared with the treatment of CK, all treatments could improve the bacterial community diversity in a certain extent, and BF showed the most significant effect, and the increasing rates in seedling period, tillering period,tuber formation period,mature period, and harvest period were 12.80% , 10.17% , 14. 15% ,5. 17% and 9.49% , respectively. The results indicated that the bio-organic fertilizer enriched with strain T3 could reduce the number of the pathogen in potato rhizosphere, and improve its microbial flora ,thus effectively controlled the potato bacterial wilt disease.