Mechanisms of biochar and vermicompost in suppression of root rot fungal disease of common bean (Phaseolus vulgaris L)

Abstract

Composts and biochar improve soil fertility and also suppress fungal soil-borne diseases through their ability to promote beneficial microbial communities. The study sought to determine the mechanisms through which biochar and vermicompost suppress root rot pathogens. Extracts of biochar and vermicompost were used for spore germination, mycelial growth tests at different concentrations. To assess the ability of biochar and vermicompost to adsorb signaling molecules from bean, root and seed exudates were filtered through biochar and vermicompost. Antagonistic activity of Trichoderma harzianum and Penicillium spp against root rot pathogens was also assessed. Germination of Pythium ultimum sporangia and Fusarium solani macroconidia was significantly inhibited by various concentrations of water extractible substances from biochar and vermicompost. Water extracts from biochar and vermicompost inhibited the germination of root rot propagules and reduced the ability of root and seed exudates to induce sporangial and conidial germination. Trichoderma harzianum and Penicillium spp significantly inhibited the growth of Pythium ultimum sporangia and Fusarium solani. The water extracts significantly reduced the growth of root rot colonies on PDA plates. Biochar and Vermicompost greatly inhibit germination of spores and mycelial growth of root rot pathogens.