Caracterización fenotípica de especies fitopatógenas del género Fusarium y microorganismos autóctonos con actividad antagónica aislados a partir de sectores arroceros en el Departamento Norte De Santander.

Abstract

The fungus Fusarium is one of the most relevant phytopathogenic genera affecting rice crops, causing considerable economic losses. The implementation of environmentally friendly biological control practices is essential to ensure agricultural productivity and prevent risks associated with mycotoxin contamination. The main objective of this study was to phenotypically characterize phytopathogenic species of the genus Fusarium spp. and native microorganisms with antagonistic activity isolated from rice-growing sectors in the Norte de Santander department. The study aimed to evaluate the phytopathogenicity of the Fusarium spp. isolates and the ability of the antagonists to inhibit them through mechanisms such as nutrient competition, mycoparasitism, and antibiosis. Seven phytopathogenic strains of Fusarium spp. were isolated and presumptively identified as F. solani (FA001), F. oxysporum (FA002), F. dimerum (FA003), F. decemcellulare (FA004), F. penzigii (FA005), F. sambucinum (FA006), and F. proliferatum (FA007). From rhizospheric soil, five bacterial strains were isolated and identified as Fictibacillus cf. gelatini (BA001), Bacillus cf. subtilis (BA002, BA005), B. cf. mojavensis (BA003), and B. cf. circulans (BA004), as well as three fungal strains, Trichoderma cf. harzianum (HA001), T. cf. citrinoviride (HA002), and T. cf. atroviride (HA003), showing antagonistic activity against the phytopathogens. In vitro assays were conducted to evaluate the ability of the isolated microorganisms to inhibit the radial growth and pathogenic action of Fusarium spp. The percentages of radial growth inhibition (PRGI) varied between 41.28% and 62.29% for bacterial isolates, and between 43.44% and 70.72% for fungal isolates. Furthermore, the fungal isolates showed a higher frequency at level 2 of antagonism, where most of them managed to inhibit pathogenic growth in two-thirds of the Petri dish. The study concluded that the effectiveness of biological control varied among the different antagonistic microorganisms against Fusarium spp. In this regard, Trichoderma cf. atroviride stood out as the most effective due to its high level of mycoparasitism, while Fictibacillus cf. gelatini and Bacillus cf. mojavensis exhibited consistent inhibition against all evaluated strains, positioning them as promising agents for biocontrol in rice crops. This approach to biological control not only aims to reduce the economic losses associated with Fusarium spp. but also to promote more sustainable and environmentally friendly agricultural practices.