Abstract: This study selected several actinomycetes from 50 strains of the saline-alkali soils of Hexi Corridor in Gansu Province which have been proved to be resistant to Rhizoctonia solani by antagonistic test, which would provide new strains resources in crop disease control. Pair culture method, growth rate method and tissue culture method were used to select antagonistic bacteria. The results of antagonistic test showed that there were 4 strains with antagonism to Rhizoctonia solani, which were named Ⅰ 18-5-2, Ⅲ 22-3-12, Ⅳ 16 -3-2 and DC009-1-23. From above four strains, Ⅳ 16-3-2 and DC009-1-23 had a higher antagonism and the diameters of inhibiting bacteria circle were 20.5 mm and 15.5 mm. By rescreening these two strains with higher antagonism from fermentation broth, the result showed that their mycelial growth inhibition rates were 89.02% and 80.49%. Biopsy tests showed that the control efficiency of IV 16-3-2 and DC009-1-23 to Rhizoctonia solani reached 54.29% and 45.71%, respectively. According to morphological characteristic and phylogenetic analysis based on 16S rRNA gene sequence, the strain Ⅳ 16-3-2 was preliminarily identified to be Streptomyces variabilis while the strain DC009-1-23 was identified to be Streptomyces lilaceus.

Key words: Rhizoctonia solani, Actinomycetes, Saline-alkali soils, Biological control