Physiological and biochemical characterization of biochar-induced resistance against bacterial wilt of eggplants

The abrupt variation in climatic patterns has become a global concern in terms of food security. Biochar, known to ameliorate climatic adversities by sequestering carbon and activating systemic resistance pathways in plants, has become increasingly relevant. Therefore, the study was aimed to characterize leaf waste biochar (LWB) by Fourier-transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray (SEM-EDX) and X-ray diffraction analytical techniques as well as determination of its impact on the development of bacterial wilt (BW) in eggplant (Solanum melongena) caused by Ralstonia solanacearum (RS). The effect of LWB on the physiology and defence-associated biochemistry of eggplants was investigated thoroughly. Eggplants either inoculated (+RS) or uninoculated (-RS) were cultivated in potting mixture containing 3 and 6% (v/v) LWB separately. In comparison with substrate (soil only), percentage disease index was significantly reduced (71%) in plants grown in 6% LWB-amended treatments. Biochar-induced increase in level of total chlorophyll content as well as in biochemicals such as phenolics, flavonoids and peroxidases were evident on plants in terms of resistance response against BW. Moreover, biochar also significantly affected the level of NPK in the eggplants. In conclusion, biochar-triggered biochemical alterations played a pivotal role in the management of BW along with the curing of the disease-infested soils.