Hydrolysed CH powder (2.0 g) was dissolved in 50 mL sterile
distilled water before adjusting the pH to 5.8 and autoclaved.
CH was used at various concentrations of 25, 50, 100 and
200 mg L−1. Salicylic acid (Sigma) was dissolved in distilled
water to a final concentration of 10 mg mL−1, pH adjusted to
5.8 and autoclaved (Kang et al. 2006). SA was used at different
concentrations of 25, 50, 100, and 200 mM.