棉花苗期病害拮抗细菌的筛选及其防效测定

从山东德州棉田采集病株根际土样12份,以棉花立枯丝核菌(Rhizoctonia solani)为指示菌,采用对峙法对平板稀释法分离的菌株进行抑菌初筛,共筛选出具有拮抗作用的细菌菌株11支.其中D24菌株对上述指示菌皆有很强的拮抗效果,该菌的发酵液对棉花立枯丝核菌、棉花黑斑病菌(Alternaria macrospora)、棉花红腐病菌(Fusarium moniliforme)、棉花枯萎病菌(Fusarium oxysporum)4种常见的棉花苗期病菌也有很好的抑制作用.室内小区试验表明,棉苗用D24菌株发酵液处理后,防效可达50.1%.

Screening of Antagonistic Bacteria Against Cotton Seedling Diseases and Measure of Controlling

Having collected 12 samples of soil from cotton planting regions in Dezhou,Shandong Province,and using confronted culture method in dilute microbe,we had separated 11 strains of antagonistic bacteria on Rhizoctonia solani.Their antagonistic ability against pathogens of cotton seedling diseases including Rhizoctonia solani,Alternaria macrospora,Fusarium moniliforme and Fusarium oxysporum showed much difference in vitro laboratory experiment.We discovered the strain D24 had much strong and stable antagonistic capacity.Inhibitive effect of the fermentative extracts of the strain D24 against growth of four pathogens of cotton seedling diseases were respectively 84.6%,82.7%,81.2%,72.8%.Using the fermentative extracts of the strain D24 to treat the seedling of cotton,it had no effect with germination of cotton.The strain D24 was dealt with cotton seedling in the spot where we had brought some soil from Dezhou.The results showed that control of D24 treatment on cotton seedling diseases reached 50.1% as compared with the control.The morphology,culture characteristics and physiological properties of strain D24 extremely similar to physiological properties of Bacillus Cohn,so the strain D24 is tentatively confirmed as Bacillus Cohn.