BIOCHEMICAL AND PHYSIOLOGICAL ELUCIDATION OF BIOCHAR INDUCED DEFENSE RESPONSE ACTIVATION AGAINST BACTERIAL LEAF SPOT IN CHILIES

Abstract

Biochar plays an important role in improving the plant growth and activating defense mechanisms against biotic and abiotic stresses. In our study, the focus was on the effect of biochar made from rice straw and flyash on plant growth and development of Xanthomonas campestris pv. vesicatoria causing bacterial leaf spot in chilies. The chilli plants were grown in different substrate compositions containing either only soil or amended with Rice straw biochar (RSB)/and flyash at the rate of 3%, each. Rice straw biochar had a positive effect on plant growth, in the form of increased root and shoot weight. In comparison to flyash and soil only treatment, the application of biochar has enhanced the production of phenols, catalase, peroxidase and flavonoids. The rise in level of defense related biochemical resulted in significant reduction of bacterial leaf spot development in chilies grown in biochar amended soil. Moreover, RSB had also shown a significant in vitro inhibitory effect (up to 50% or more) on different pathogenic fungi and bacteria. Disease severity and incidence was significantly minimized among the plants grown in RSB containing substrate as compared to other substrate compositions. Overall, our findings indicated a positive effect of RSB amendment on plant health, as well as by enhanced protection against bacterial leaf spot in chilli plants. Biochar addition in soil not only improve fertility but also helps in achieving long-lasting Carbon sequestration goals. The ability of biochar to influence plant growth and defense pathways apparently contributes towards its ability of disease suppression.