Linking the Belowground Microbial Composition, Diversity and Activity to Soilborne Disease Suppression and Growth Promotion of Tomato Amended with Biochar

Abstract

Biochar, in addition to sequestering carbon, ameliorating soil, and improving plant performance, can impact foliar and soilborne plant diseases. Nevertheless, the mechanisms associated with suppression of soilborne diseases and improved plant performances are not well understood. This study is designed to establish the relationships between biochar-induced changes in rhizosphere microbial community structure, taxonomic and functional diversity, and activity with soilborne disease suppression and enhanced plant performance in a comprehensive fashion. Biochar suppressed Fusarium crown and root-rot of tomato and simultaneously improved tomato plant growth and physiological parameters. Furthermore, biochar reduced Fusarium root colonization and survival in soil, and increased the culturable counts of several biocontrol and plant growth promoting microorganisms. Illumina sequencing analyses of 16S rRNA gene revealed substantial differences in rhizosphere bacterial taxonomical composition between biochar-amended and non-amended treatments. Moreover, biochar amendment caused a significant increase in microbial taxonomic and functional diversity, microbial activities and an overall shift in carbon-source utilization. High microbial taxonomic and functional diversity and activity in the rhizosphere has been previously associated with suppression of diseases caused by soilborne pathogens and with plant growth promotion, and may collectively explain the significant reduction of disease and improvement in plant performance observed in the presence of biochar.

Biochar amendment decreases soil microbial biomass and increases bacterial diversity in Moso bamboo ( Phyllostachys edulis ) plantations under simulated nitrogen deposition

“…This demonstrated that biochar amendment altered soil microbial composition in Moso bamboo forests, which concurs with Khodadad et al (2011) and Perry et al (2015). Jaiswal et al (2017) observed a significant decrease in Acidobacteria abundance in the biochar-enriched soil rhizosphere. Acidobacteria generally prefer oligotrophic environments and lower pH soils; therefore, it is possible that the reduction in Acidobacteria was a response to the biochar-related shift to a more neutral and copiotrophic environment (Jaiswal et al 2017).…”

“…Jaiswal et al (2017) observed a significant decrease in Acidobacteria abundance in the biochar-enriched soil rhizosphere. Acidobacteria generally prefer oligotrophic environments and lower pH soils; therefore, it is possible that the reduction in Acidobacteria was a response to the biochar-related shift to a more neutral and copiotrophic environment (Jaiswal et al 2017). Xu et al (2014) found that biochar amendment in an acidic soil (pH 4.48) changed the relative abundance of some microbes that are related to C and N cycling.…”

Biochar and Trichoderma harzianum for the Control of Macrophomina phaseolina

“…In vitro assays using BCHs produced from eucalyptus wood (600 ºC) and pepper residues (350 ºC), when added at different concentrations (0, 0.5, 1, and 3%) to the culture medium, did not inhibit mycelial growth of the phytopathogen Fusarium oxysporum f. sp. radicis lycopersici compared to the unmodified control (without biochar), indicating that for the tested pathosystem the direct effect of biochar cannot be considered a mechanism of disease suppression [20].…”

“…Similarly, the application of biochar from eucalyptus wood (600 ºC) to the soil resulted in a decrease of up to 61% in fusarium wilt in tomato plants, just as plants cultivated in soil without biochar showed wilt symptoms one day before those containing biochar [20]. The authors emphasized that application of biochar to the soil stimulated rhizospheric microbial diversity related to the genera known for promoting plant growth, suppressing diseases, possible ecological roles (decomposition of organic compounds) and biological nitrogen fixation.…”

Core and Differentially Abundant Bacterial Taxa in the Rhizosphere of Field Grown Brassica napus Genotypes: Implications for Canola Breeding

“…produce complex compounds that are antagonistic toward many fungal pathogens and also have antibiotic properties (Chernin et al, 1995(Chernin et al, , 1996. Neisseria is associated with disease suppressive soils (Almario et al, 2013;Adam et al, 2014), Peredibacter suppresses soil-borne disease (Jaiswal et al, 2017), and Pseudomonas induces systemic resistance against pathogens such as the soil-borne Rhizoctonia solani (Nandakumar et al, 2001). Streptosporangium is an Actinomycete known to produce antimicrobial compounds (Hardoim et al, 2015).…”