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.
Highlights
Loss of soil organic matter and associated loss of soil microbial diversity and activity due to intensive agriculture has contributed to an increase in soilborne plant diseases[1]
Mechanisms possibly linked to the impact of biochar on progress of diseases caused by soilborne pathogens include: (i) improved nutrient supply and availability; (ii) enhanced soil physiochemical characteristics; (iii) altered pathogen growth, survival, and activity; (iv) induced systematic plant defense mechanisms; and (v) altered soil microbial abundance, diversities, and activities
No comprehensive relationship has been established between biochar-induced changes in microbial community structure, diversity and activity, and the concomitant suppression of diseases caused by soilborne pathogens and enhanced plant performance
Summary
Loss of soil organic matter and associated loss of soil microbial diversity and activity due to intensive agriculture has contributed to an increase in soilborne plant diseases[1]. The application of biochar (the solid co-product of biomass pyrolysis) to soil has been shown to have the potential to suppress plant diseases caused by both soilborne and foliar pathogens[4,5,6,7], which may be a function of biochar dose, feedstock, and production conditions[7]. Mechanisms possibly linked to the impact of biochar on progress of diseases caused by soilborne pathogens include: (i) improved nutrient supply and availability; (ii) enhanced soil physiochemical characteristics; (iii) altered pathogen growth, survival, and activity; (iv) induced systematic plant defense mechanisms; and (v) altered soil microbial abundance, diversities, and activities. No comprehensive relationship has been established between biochar-induced changes in microbial community structure, diversity and activity, and the concomitant suppression of diseases caused by soilborne pathogens and enhanced plant performance. This soilborne Ascomycete, the causal agent of Fusarium crown and root rot (FCRR), is a destructive pathogen of tomato in both greenhouse and field production, reducing yields by 15–65%28
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