Induced resistance against Fusarium solani root rot disease in cassava plant (Manihot esculenta Crantz) promoted by salicylic acid and Bacillus subtilis

ABSTRACT Root rot disease of cassava is one of the major diseases in Thailand, widespread incidence of soil-borne pathogens has been found to affect more than 80%. The research aims to investigate the effect of elicitors as salicylic acid and Bacillus subtilis strain JN2-007 for inducing resistance against root rot disease by Fusarium solani in cassava. The experiment was carried out in a susceptible cassava cultivar to test the efficacy of elicitors in the biochemical response of plant defense mechanisms pertaining to hydrogen peroxide (H2O2) and enzyme activities. The results indicated that pathogenicity test of F. solani isolate SHRD1 caused the brown lesions around the inoculation point on cassava roots. Subsequently, salicylic acid and JN2-007 reduced mycelial growth of F. solani (11.83%–57.73% at day 7), as well as disease severity in the cassava plants at 14 days after the inoculation compared to that of the negative control (28.12%–39.58% compared to 68.75%). Furthermore, salicylic acid at a concentration of 500 µl. L−1 could induce H2O2, level of peroxidase, polyphenol oxidase, and catalase activities that were highest at 24 h after pathogen inoculation. The results suggested that elicitors played an important role as a plant defense inducer, leading to reduced Fusarium root rot disease.