a survey on biocontrol of rhizoctonia solani kuhn damping-off of tomato with bacillus subtilis

in this research, the antagonistic effects of bacillus subtilis isolates against the causal agent of tomato damping-off, rhizoctonia solani were surveyed under laboratory and greenhouse conditions. isolates b4 and b18 showed the most inhibition ratio in the volatile and non-volatile metabolites tests which were 50.3% and 58.6% respectively. the six out of 25 isolates studied more and their antagonistic effects were surveyed under greenhouse conditions as inoculated into soil and covered on root and crown of seedlings. interaction among the bacterial isolates and the fungus was calculated as percent of increasing of seedling length, percent of increasing of seedling dry weight and percent of decreasing of diseased plants. the results showed that bacterial isolates have different antagonistic effects. in the greenhouse tests, both methods, b2 isolate was the best at significant decreasing of disease rate and at significant increasing of considered growth factors in this test.