Biological control of soybean damping-off by antagonistic rhizobacteria.

Experiments were carried out with 133 bacterial isolates that were collected from soybean rhizosphere. These strains were used to investigate their biocontrol traits in vitro and their ability to suppress the soybean damping-off in vivo (soil and seed treatments). Three highly effective isolates were selected from these antagonists for subsequent studies. According to the biochemical, physiological and morphological tests, these isolates (B-2, B-12 and B-80) were identified as Bacillus spp. In soil treatment, the isolate B-3 with 70.8%, B-12 with 66.7%, B-80 with 54.2% had the highest effect on reducing the soybean damping-off. In seed treatment, the isolates B-43 with 62.5%, B-12 with 58.4 and B-80 with 45.8%, had the greatest effect on reducing the disease. These isolates produced volatile metabolites that inhibited mycelial growth of Phytophthora sojae.