Effect of salicylic acid and chitosan on response of rice against Fusarium fujikuroi the causal agentof rice root and crown rot

This study was carried out to investigate the effect of salicylic acid (sa) and chitosan (chi) on the response of rice to Fusarium fujikuroi, the causal agent of root and crown rot of rice plant. The effect of chitosan and salicylic acid with the concentrations of 200 and 400 ppm on mycelial growth of the pathogen was measured. Furthermore after 0, 24, 48, 72, 96, 144 and 288 hours of inoculation, growth traits of the plant and enzyme activity of peroxidase and catalase were evaluated in rice seedlings of a susceptible cultivar namely Tarom. Salicylic acid and chitosan in 400 ppm had the most mycelial inhibitory effect with 35.57 and 24.29% respectively. Both treatments could significantly reduce disease symptoms; the least disease severity was assessed 37.8 and 41.7 % in 200 and 400 ppm concentration of salicylic acid and chitosan respectively. Sa-200 and chi-400 pretreatment could significantly (p < /em><0.05) increase the shoot and root length and root volume of seedlings compared to control. The maximum level of peroxidase activity was assessed 96 hours after inoculation in 200 and 400 ppm concentration of salicylic acid and chitosan respectively. The minimum level of catalase activity was assessed 48 hours after inoculation in 200 and 400 ppm concentration of salicylic acid and chitosan respectively. Thus salicylic acid and chitosan could effectively induced systemic resistance in rice resulted in the reduction of disease severity.