Effect of harvest season, nitrogen, phosphorus and potassium on root yield, echinacoside and alkylamides in Echinacea angustifolia l. in chile

Echinacea angustifolia L., originally from North America, is one of the three Echinacea species that traditionally have been used to stimulate the body's immune system. The active principles of the species are mainly echinacoside, alkylamides and cynarin. The amount of these components in the roots depends on many factors, which have to be investigated. The objectives of this research was to determine the influence of phenological stage and N, P and K on root yield, echinacoside and alkylamides content on a one year old E. angustifolia crop. Experimental design was a randomised complete block with 4 replicates and 12 treatments with a factorial arrangement of three levels of nitrogen (0, 150, and 300 kg ha(-1)), two of P (0.100 kg ha(-1)) and two of K (0.100 kg ha(-1)). Echinacoside and alkylamide contents were determined using an HPLC. Results indicate that echinacoside and alkylamides content are strongly influenced by the phenological stage. Highest contents of echinacoside were observed before immature buds elongate 1 to 2 cm above the crown (stage = R-2) and echinoside drops rapidly after this phenological stage, except at one location. Also, a negative correlation between root yield and echinacoside and alkylamides content was observed. N, P, K or their interactions did not significantly influence root yield at the first harvest date. A N x P significant interaction for alkylamides was detected. Also K had a significant effect on echinacoside content. When the supply of K was increased the amount of echinacoside became higher at both harvest dates. However, individuals of E. angustifolia show very high variability for root yield and active principles, which made difficult to detect statistical differences among treatments.