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Biological control of soybean diseases and growth promotion of soybean (Glycine max) by beneficial bacteria

Rosalie Calderon: College of Agriculture, Benguet State University

<div>The use of beneficial bacteria having antagonistic activity against pathogens or plant growth promoting activity would be a viable strategy to lessen chemical inputs for crop production. The aims of this study were to screen, identify and characterize bacteria from the soybean rhizosphere that promote the growth and health of soybean. From the 1,440 soybean-associated bacteria (SABs) isolated from the soybean rhizosphere, 46 SABs showed significant antifungal activities. The eleven most promising bacteria, mostly identified as <em>Bacillus sp</em>., were further tested in laboratory and greenhouse conditions. Soybean seeds were treated with each SAB and carboxymethylcellulose (CMC) as a sticker before sowing. In pathogenicity tests conducted in plastic pouches with the fungus <em>Rhizoctonia solani</em>, soybean seedlings treated with SAB4, SAB7, SAB8, and SAB10 exhibited significantly less symptomatic area compared to the untreated control (5 – 7% vs. 50 - 70% root tissue lesions of individual seedlings). The second best group of the SABs was SAB1, SAB3, SAB6 and SAB9, which showed 10 - 25% symptomatic area. Effects of SAB2 and SAB11 treatments were not significantly different from the untreated control and the CMC-coated seeds. Under greenhouse conditions, the soybean plants treated with SAB9, SAB6, SAB7, and SAB10 were significantly taller and more vigorous than the plants without any treatment or treated with a commercial product. These SABs are potential biological agents for disease management and growth promotion of soybean, which may lead to reduced use of synthetic pesticides and fertilizers resulting in more sustainable soybean production.</div>