The modification of method of the artificial inoculation of sunflower seedlings with phoma rot pathogen in the laboratory conditions to identify the colonizing activity of strains-producer of microbiopreparations

We carried the work in the biomethod laboratory of the crop management department of V.S. Pustovoit All-Russian Research Institute of Oil Crops. We modified the method of artificial inoculation of sunflower seedlings with a pathogen in a laboratory conditions for the secondary screening of antagonist strains from the collection of the biomethod laboratory to Phoma rot pathogen. We developed a five-point scale for evaluation of affection degree of sunflower seedlings by Phoma rot pathogen: 0 points - healthy seedlings; 1 point - darkening of the root tip, intensive development of lateral roots; 2 points - darkening of the root by a third or up to the middle, but intensive development of lateral roots; 3 points - necking of rot in the middle of the root or between the hypocotyl and the root, lateral roots are poorly developed; 4 points - root rotting to the middle or necking between the hypocotyl and the root, but intensive development of lateral roots; 5 points - complete rotting of the root, lateral roots are poorly developed or absent; 1-3 - viable seedlings; 4-5 - non-viable seedlings. The optimal period of exposure of the root tips of sunflower seedlings to the pathogen colony equal to 3 hours develops an average background of infection with the pathogen (60.0 %) already on the first day, at which it is possible to evaluate at an early stage the difference between the variants by the colonizing activity of laboratory samples of microbiological preparations.