Pre-sowing seed treatment with cold plasma and electromagnetic field increases secondary metabolite content in purple coneflower (Echinacea purpurea) leaves

The effects of seed treatment with cold plasma (2-7min), vacuum (7min), and electromagnetic field (5-15min) on Echinacea purpurea germination and performance are studied. All treatments induce faster germination but did not change the final germination percentage, except the decrease evoked by vacuum treatment. The plants grown from all groups of treated seeds have larger height, develop more leaves, some treatments increase root weight. The content of vitamin C and phenolic acids in extracts of plant leaves from the treated groups is substantially higher in comparison to the control, so that the amount of cichoric acid per plant increased up to 3.8-fold, and amount of vitamin C per plant - up to 1.9-fold. Seed treatments induce large increase in radical scavenging activity (up to 114%) in leaf extracts.