Biochar: Black Gold for Sustainable Agriculture and Fortification Against Plant Pathogens—A Review

To support the search for alternate chemical-free strategies to enhance plant growth and control plant diseases, we present an overview of the potential use of Biochar (BC) a product synthesized through pyrolysis from organic and agricultural waste used as a soil amendment, in suppressing broad range plant pathogens. A broad-spectrum BC effect contributes to the control of soil and foliar pathogens by altering the root exudates mechanism of the host plant, soil health and nutrient mobilization that affect the colonization of antagonistic microorganisms. Induction of plant defense mechanism by adding BC in potting medium to reduce foliar pathogens by the activation of defensive responses and induction of reactive oxygen species signaling in the plant system. Although few reports have been found for controlling oomycetes, viruses and bacterial pathogens through the application of BC, reports indicated that adding BC has potentially changed the soil microbiota colonization which contributes to disease suppression. BC also controls nematodes and harmful insects of plants. In addition, the main mechanisms of action for plant parasitic nematodes are changes in soil structure and could increase the biocontrol microorganism in the rhizosphere which resists nematodes colonizing and penetrating the plant system. Using BC-based amendments is a promising strategy with a carbon sequestration strategy, created on zero waste, as part of the integrated management of pathogens and parasites. Comprehensively, it is needed to be standardized the dosage and feedstock of BC in terms of sustainable production and disease control.