Fungicidal Action of Phosphite in Tobacco on Phytophthora nicotianae

Phosphite has been recommended to enhance plant resistance against Phytophthora. This work evaluated the response of tobacco (Nicotiana tobacum) to Phytophthora nicotianae following treatment with phosphite. Protection was expressed as a reduction in the rate of lesion extension after wound inoculation. Phosphite concentrations at the site o inoculation were sufficient to reduce mycelia growth in vitro. There was a close relationship between the concentration of phosphite present at the invasion site and the extent to which protection was expressed, although phosphite concentrations were never fungitoxic. Once accumulated, phosphite remained in the plant for extensive periods. Results suggest that the concentration of phosphate present at the infection site influenced the degree to which phosphite protection was observed in treated plants. In this experiment, phosphite concentrations were sufficient to reduce fungal growth by direct action. However, plant defenses would be important in completely arresting pathogen invasion

کلیدواژه ها:

tobacco ، phosphite ، phytophthora