Effect of potassium chloride on the exudation of sugars and phenolic acids by maize root and its relation to growth of stalk rot pathogen

Hydroponic experiment and incubation experiments were conducted to study the effect of potassium chloride on the exudation of sugar and phenolic acids, and the effects of major components in sugar and phenolic acids on the development of Fusarium graminearum Schwabe. The results showed that the amount of total sugar, reducing sugar and sucrose exudates by root of resistant cultivar was lower than that by root of susceptible cultivar. Potassium supply decreased exudation of total sugar, sucrose and reducing sugar in different extent significantly, especially reducing sugar. The amount of ferulic acid exudates by root of resistant cultivar was higher than that of susceptible cultivar significantly, while a reverse trend was found in chlorogenic acid. In vitro, the growth of F. graminearum was stimulated by sugar and inhibited by ferulic acid and chlorogenic acid. While the suppression effect of ferulic acid was more effective than chlorogenic acid. In conclusion, the decrease of reducing sugar content and the increase of the amount of ferulic acid in seedling root exudates with potassium supply may help to inhibit F. graminearum growth in rhizosphere.