Biochar-mediated growth promotion in Flue-cured tobacco: An insight from molecular perspective

Flue-cured tobacco is considered an important economic commodity worldwide. In order to sustain the growing demand, large quantity of fertilizers is applied to obtain more yield. Biochar is a natural growth stimulant which promotes plant growth when applied in optimum dosage. The present study elucidates the dosage-dependent relationship of biochar application with growth. Optimum biochar application enhanced plant growth, regulated enzymatic activity and promoted biomass accumulation in tobacco plant, while higher dosage produced adverse effects. Furthermore, transcriptome analysis revealed that important pathways such as photosynthesis, carbon fixation, and sucrose and starch metabolism were significantly upregulated under optimal biochar dosage (600kg/ha) and downregulated when high dosage (1800kg/ha) was applied to tobacco plant. Overall, these result highlight that optimum application of biochar improves plant growth through modulation of carbon metabolic pathways, whereas higher biochar dosage disturbs the crucial source-sink balance of organic compounds.