Study on the Resistance Induced by Salicylic Acid Against Phytophthora capsici in Pepper

Pepper Phytophthora blight caused by Phytophthora capsici L. is the most destructive disease for reducing pepper yields in the world. Building up varietal resistance and induced resistance to the disease are of agricultural importance. In this paper, the disease resistance induced by salicylic acid (SA) against P. capsici were studied by using 4 hot pepper lines with different resistant abilities and 1 P. capsici strain with middle pathogenicity. Results show that SA could induce significantly the resistance of pepper seedlings to P. capsici, but CaCl2, KH2PO4 and VAM could not. SA at a relative low concentration from 0.15to 0.3 g·L-1 had no antifungal activity in vitro against P. capsici. That means that the disease resistance enhancement of the plants treated with SA is due to the induced effect, but not the antifungal effect of SA. About 1-5 days interval between SA-treatment and challenge inoculation was sufficient to induce the disease resistance of hot pepper.The resistance could remain more than 20 days after treatment with SA.