Efficiency of rhizobacteriaBacillusspp. in the control of Macrophomina phaseolina in vitro agent of stem rot of castor bean (Ricinus communis L)

Abstract

This study aimed to evaluate the efficiency in controlling the fungus Macrophomina phaseolina by Bacillus strains isolated from the rhizosphere and rhizoplane of wild and cultivate castorbean. The strains were evaluated in pairing with the pathogen Macrophomina phaseolina isolated in Pelotas (RS), and also antibiosis, and inhibition of bacteria of the same gender. Wild strains were more effective for control of the pathogen in paired isolates from wild castor bean inhibited fungal growth more efficiently and RZ 1 a strain that could further inhibit the fungus, decreasing by 9% its development, other strains of proved niche with similar efficiency. The strain RZ 2, another isolate wild, managed through its metabolites inhibit the growth of the fungus in 24%, in this test strains isolated from cultivar had satisfactory results by inhibiting the fungus in 23 and 21% of the strains RZE 4 RP2 respectively. The isolates obtained good results for the production of volatile metabolites and strains RP 5 was fungistatic and strains as RPE 4, and RZE 4, RZE 5 reduced the number of conidia. Few bacteria were able to inhibit the indicator microorganism of the same gender, like RP1, RZ 2 and RPE 9. As the results show bacteria of the genus Bacillus are effective in controlling this pathogen mainly when isoled fron wild environment.