Evaluation of Biochar Plant Extract Composites from Solanum incanum Fruits in Controlling Ralstonia solanacearum Based Bacterial Wilt in Tomato Plants

Biochars were prepared at pyrolysis furnace temperatures of 300℃ and 500℃ and characterized by FT-IR and SEM. Plant extract biochar composites were prepared by adsorbing plant extract onto the biochar. The antibacterial activity of the biochars and biochar composites was done in the in vitro and in vivo studies. FT-IR spectra showed peaks at 3415 cm-1, 2931 cm-1, 1596 cm-1, and 1398 cm-1 for O-H, C-H, C=C, and C-O-H groups respectively. The SEM images showed differences in morphological properties. FT-IR spectra of biochar composites showed additional functional groups as well as shifting of the peaks. SEM images of biochar composite showed diminishing of porous structure of the biochars. Symptoms of bacterial wilt in Ralstonia solanacearum inoculated pots were observed 14 and 18 days post-inoculation (dpi) for biochars prepared at 300 ℃ and 500 ℃ respectively. In contrast, the symptoms were observed 20 dpi for 1% BC, 22 dpi for 3% and 4% BC, 24 dpi for 5% BC 300℃ and 36 dpi for 7% BC 300 ℃ treatment. For the BC 500 ℃ treatment, the symptoms were observed 20 dpi for 1% BC, 22 dpi for 2% BC and 24 dpi for 3% and 4% BC. No disease symptoms were observed at 5% and 7% BC 500 ℃. This results suggested that biochar composite for 500℃ is more effective in control of bacterial wilt and therefore, can be used as substitute for synthetic pesticides.