Activity of rhizobacteria antagonistic to Fusarium oxysporum f. sp. passiflorae in soils cultivated with monocotyledonous plants1

Abstract

In spite of the importance of passion fruit cultivation in Brazil, this activity has been forced to be itinerant, due to the occurrence of diseases in producing regions, in particular fusariosis. The use of rhizobacteria is a potential control alternative, but other improvements are necessary to guarantee the activity of these bacteria in the field. This study aimed at evaluating the influence of three monocotyledonous groups on the activity of rhizobacteria antagonistic to Fusarium oxysporum f. sp. passiflorae (Fop). Rhizobacteria were isolated from passion fruit plants and tested for the production of diffusible and volatile compounds, as well as chitinases that inhibit Fop. From a total of 167 isolates, two produced volatile compounds, 21 diffusible compounds and 32 chitinases. Three compatible combinations of isolates that had at least two action mechanisms against Fop and could grow in a wide pH range were applied in pots with sorghum, millet or maize, in addition to pots left fallow (control), in a greenhouse. The microbial biomass carbon, soil basal respiration, metabolic quotient and activity of the acid phosphatase enzyme were evaluated. The interaction between the cultivated species and rhizobacterial combinations was significant only for the metabolic quotient, whose values tended to be higher under millet cultivation in combination 3 (R77/R95/R104/R120), the most metabolically diversified one. The highest activity of acid phosphatase was also obtained with millet. The results for enzymatic activity and metabolic quotient indicate that millet provides a greater activity of the antagonists in the soil.

Relaciones fisiológicas entre la maduración del fruto y las semillas de tomate de árbol (Solanum betaceum Cav.)

“…Otros microorganismos empleados en el control biológico de fusarium en pasifloras son rizobacterias, Azospirillum spp., y Azotobacter spp. (Santos, Macamo, Haddad, & Silva, 2017;Quiroga-Rojas, Ruiz-Quiñones, Muñoz-Motta, & Lozano-Tovar, 2012;Barbosa & Meza, 2009). Se deben erradicar plantas enfermas en bolsas rojas de riesgo biológico y llevar a cabo desinfección de los sitios con cal viva u otras sustancias desinfectantes, como una buena estrategia de manejo (Hoyos & Castillo, 2015).…”