Antagonism to Macrophomina phaseolina and growth promotion in bean by cave bacteria filtrate

Beans are one of the most important foods for the majority of the world's population, and Brazil is the third largest producer. This production can be affected by pests and diseases, such as gray stem rot, caused by the fungus Macrophomina phaseolina, which is difficult to control due to the low efficiency of chemical products. One of the viable alternatives is the use of microorganisms and/or secondary metabolites to control the pathogen and promote plant growth. The objective of this work was to test the antagonistic action of the filtrate of cave bacteria against M. phaseolina and promote the growth of common bean. To determine the period of infection of the phytopathogen, a severity test was carried out, and subsequently the filtrate of cave bacteria, identified as IS22, was applied at different times of inoculation of the phytopathogen in the bean plant BRS Esteio. Plant height, fresh and dry weight of shoots, root length, fresh and dry weight of roots were evaluated. The fungus did not manifest symptoms in the plant, but in relation to the growth promotion of the common bean, the filtrate provided a significant increase in the analyzed variables from the V3 stage. It is concluded that the tested filtrate is a promising biostimulant for the market.