Deciphering the microbial mechanisms of biochar involved in suppression of fusarium crown and root rot in tomato
A. JAISWAL (1), Y. Elad (2), E. Graber (2), E. Cytryn (2), O. Frenkel (2) (1) Faculty of Agriculture, Hebrew University, Israel; (2) Agriculture Research Organization (ARO), The Volcani Center, Israel

Biochar, in addition to carbon sequestration, soil amelioration and improvement of plant performance, can significantly reduce plant diseases. Nevertheless, the mechanisms associated with soilborne-disease suppression are not fully understood. This study tested the effects of two biochars at concentration of 0-3% (w:w) on fusarium crown and root rot (FCRR) of tomato caused by Fusarium oxysporum f. sp. radices-lycopersici (FORL), with an emphasis on mechanisms of disease suppression. Biochar at higher concentrations suppressed FCRR of tomato by up to 79%. Furthermore, biochar significantly reduced the Fusarium root colonization and survival in soil. Yet, direct toxicity of biochar to FORL was not observed in in vitro assay. Biochar amendment significantly increased the culturable counts of general bacteria, fluorescent Pseudomonas spp., Trichoderma spp. (well-known biocontrol and plant growth promoting agents) and other microorganisms. Indeed, biochar-stimulated fluorescent Pseudomonas have antagonistic activity towards FORL. Illumina sequencing analyses of 16S rRNA gene showed substantial differences in rhizosphere bacterial taxonomical composition between biochar-amended and control soils. Nevertheless, biochar amendment caused a significant increase in microbial diversity (Shannon’s diversity, phylotype richness) and microbial activities (respiration rates, dehydrogenase and other enzymes activities), concurrent with increased plant growth and disease suppression. High microbial diversity and activity in the rhizosphere has been previously associated with soilborne diseases suppression and growth promotion, and this may collectively explain the significant reduction of disease and increase in plant growth observed in the presence of biochar. 

Abstract Number: P4-95
Session Type: Poster