Objectives Biocontrol bacteria were screened from 109 strains of plant growth promoting rhizobacteria (PGPR) of Trifolium pratense in Minshan. Their promoting effects were identified and their biocontrol characteristics were studied for the practical use.
Methods The plate confrontation method was used to screen the excellent biocontrol strains, and siderophore producing capacity of the strains was measured and the 16S rRNA gene sequence of these strains was analyzed.
Results Eight strains of biocontrol bacteria showed an antagonistic effect on 3 pathogenic fungus (Rhizoctonia solani, Fusarium oxysporium f. sp. Cucumerinum, and Fusarium oxysporum f. Niveum). The strains were MHS3, MHS7, MHS9, MHS27, MHS31, MHS38, MHS39 and MHS48, and among them, the inhibition rates of the strains of MHS27 and MHS31 against Rhizoctonia solani were 40.1% and 47.1%, the inhibition rates of the strains of MHS7 and MHS48 against Fusarium oxysporium f. sp. Cucumerinum were 26.1% and 22.8%, and the inhibition rates of the strains of MHS27 and MHS31 against Fusarium oxysporum f. Niveum were 34.0% and 30.5%. The siderophore produced was one of the main ways to antagonize 3 pathogenic fungi in biocontrol bacteria (MHS7, MHS27, MHS31, MHS48). The results of the 16S rRNA gene sequence analysis showed that the strain MHS7 was Bacillus tequilensis, the strain MHS27 was Bacillus proteolyticus, the strain MHS31 was Pseudomonas paralactis, and the strain MHS48 was Klebsiella oxytoca.
Conclusions These four excellent PGPR strains which were screened from the Trifolium pretense rhizosphere of Minshan can provide a support for the application of bio-fertilizer in the future.
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