Effect of salicylic acid and methyl jasmonate on morphological traits, enzymatic activity and essential oil percentage of purple coneflower plant (Echinacea purpurea L.) in Zanjan climate

In order to evaluate the effects of salicylic acid, methyljasmonate and their interactions on some features of Echinacea purpurea L., a factorial experiment was conducted based on randomized complete block design with three replicates in Zanjan climate conditions. Treatments included three levels of salicylic acid (0, 1 and 2 mM) as first factor and methyl jasmonate at three levels (0, 0.5 and 1 mM) as second factor. Traits which were studied were as follow: plant height, leaf area, number of flowers and percentage of plant dry weight as morphological traits, total chlorophyll, carotenoids and flavonoids as physiological traits, activity of antioxidant enzymes such as peroxidase and catalase and essential oil percentage. Results showed that the interaction of 1 mM salicylic acid and 0.5 mM methyl jasmonate had the highest effect on the activity of catalase and peroxidase enzymes activity. Foliar application of salicylic acid at the 1 mM increased the height, leaf area and number of flowers. Among the different concentrations of methyl jasmonate, the concentration of 1 mM had the highest effect on total chlorophyll, carotenoids and flavonoids compared to salicylic acid treatments and the concentration of 2 mM salicylic acid which had the highest effect on essential oil percentage compared to methyl jasmonate treatments. In conclusion, the simple effect of 2 mM salicylic acid and 1 mM methyl jasmonate foliar application significantly improved most of the traits measured in this study compared to control treatment.