Abstract

BLANCO, Erika Lorena  and  CASTRO, Yulimar. Antagonism of rhizobacteria on phytopathogenic fungi, and their microbial activity with biofertilizer, biostimulant and biocontroller potential. Rev. colomb. biotecnol [online]. 2021, vol.23, n.1, pp.6-16.  Epub Aug 10, 2021. ISSN 0123-3475.  https://doi.org/10.15446/rev.colomb.biote.v23n1.84808.

Rhizobacteria are part of the large number of microorganisms that act as biocontrol agents, producing metabolites that induce systemic resistance in plants and inhibit the growth of pathogens. The objective of this research was to evaluate the capacity of ten rhizobacteria of the genera Rhizobium, Bradyrhizobium, Sinorhizobium, Ochrobactrum and Pseudomonas to produce hydrogen cyanide (HCN), siderophores and indole acetic acid (IAA), dissolve phosphate, fix nitrogen and inhibit the growth of phytopathogens. All the corresponding physiological and biochemical tests were carried out, in addition to an in vitro antagonism test against the phytopathogens Fusarium oxysporum, Colletotrichum gloeosporioides and Rhizoctonia solani. Five strains produced a greater amount of IAA with respect to the others in the presence of tryptophan, the strain ES1 (Ochrobactrum sp.) produced HCN, 50% of the evaluated strains released siderophores, 60% solubilized phosphorus and all were positive for nitrogen fixation. Nine strains inhibited the growth of F. oxysporum by 40% to 65%. The Alf strain (Pseudomonas fluorescens) inhibited the growth of C. gloeosporioides by 22% while none inhibited the growth of R. solani. The rhizobia tested and the Pseudomonas fluorescens strain may have favorable effects on plants through direct and indirect mechanisms, or a combination of both, making them a sustainable option for crop production.

Keywords : rhizobia; Pseudomonas fluorescens; plant growth promoter mechanisms; Fusarium oxysporum; Colletotrichum gloeosporioides.

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