Morphological characteristics and total phenol concentration in hydroalcoholic extract of Echinacea purpurea L. influenced by different nitrogen sources

The nutrients are considered as the most important factor affecting morphological traits and secondary compounds in the medicinal plants. The method of plant nutrition is very important in the effective absorption of these elements. To evaluate the effects of different nitrogen sources including urea, nitrogen-nanofertilizer, and amino acids on the morphological characteristics and concentration of polyphenolic compounds of Echinacea purpurea L., a factorial experiment was conducted in a completely randomized design with 27 treatments and four replications. The experimental treatments included the urea fertilizer at three levels of 0, 100, and 200 kg ha-1, foliar application with nitrogen-nanofertilizer at three levels of 0, 1, and 3 g l-1, and foliar application with commercial amino acid Fermolife at three levels of 0, 1, and 3 g l-1. The traits were measured at the full flowering stage of plants. The results showed that the highest amount of fresh and dry weight of leaves and fresh weight of roots was obtained in the 3 g l-1 nitrogen-nanofertilizer treatment and the highest amount of aerial parts dry weight was measured in the combined treatment of 1 g l-1 nitrogen-nanofertilizer and 3 g l-1 amino acids. Most of the plant traits were increased by the foliar application of nitrogen-nanofertilizer and amino acids compared to the urea fertilizer use. The effect of different nitrogen fertilizers on the concentration of polyphenolic compounds in the plant was also significant. The highest amount of total phenol was obtained in the simultaneous application of 200 kg ha-1urea, 3 g l-1 nitrogen-nanofertilizer, and 1 g l-1 amino acids treatment. Overall, the results showed that feeding E. purpurea with the nitrogen fertilizers could improve the morphological traits and total phenol concentration in the plant.