Chitosan in the induction of resistance to the damping off tomato seedlings caused by Rhizoctonia solani Kuhn

The objective of this study was to evaluate the potential of chitosan in the damping off tomato resistance induction caused by Rhizoctonia solani . The tomato seeds were submerged in solution with chitosan for twenty minutes in concentrations of 0.25; 0.5; 1 and 2% and in the control (distilled water only). The seeds were sown in polystyrene trays containing substrate inoculated with R. solani and kept in a growth chamber with 12 hours photoperiod and temperature of 25 oC ± 2 °C for 14 days. After this period we evaluated the survival of seedlings, length and fresh weight and activity of the enzyme phenylalanine ammonia lyase (PAL), chitinase and β-1,3-glucanase. The results showed that chitosan when applied to the treatment of tomato seeds at a concentration of 0.30%, favoring the survival of seedlings inoculated with the pathogen substrate. This result is mainly related to the activation of resistance mechanisms in the plant, evidenced by activation of FAL enzymes, chitinase and β-1,3-glucanases.