The effect of salicylic acid application on the reduction of wheat septoria leaf blotch (STB) symptoms causing by Zymoseptoria tritici

This study was carried out to evaluate the effect of salicylic acid on the reduction of disease severity of septoria tritici blotch (STB) in three tetraploeid and three hexaploeid wheat cultivars, under controlled conditions at seedling stage. The 10-day-old seedlings were initially treated with 0 (control), 1, 2 and 4 mM of salicylic acid with a handy sprayer. After 24 hrs, the seedlings were inoculated with fungal spore suspensions adjusted at 107 sopres/ml. The disease progress was evaluated 21 days post inoculation based on visual estimation of the percentage of leaf area with necrotic lesions bearing pycnidia. The results showed that there were significant differences on the reduction of disease severity among different concentrations of applied salicylic acid as well as among cultivar/ concentration interactions. In addition, the results showed that application of salicylic acid reduced disease severity of both tetraploid and hexaploid wheat cultivars and 1 mM salicylic acid was the most effective concentration on the reduction of disease severity. Although, the disease severity was significantly reduced by application of 2 and 4 mM salicylic acid, the effectiveness of these concentrations was less than application of 1mM. Overall, these results revealed that activation of plant defense systems through application of salicylic acid could play a significant role in systemic acquired resistance against STB disease.