Effect of latitude on narrow-leaved purple coneflower (Echinacea angustifolia DC.) yield and phytochemical quality

Abstract

The worldwide increase in demand for plant-derived drugs has increased interest in medicinal plants as alternative cash crops across western Canada. The objective of this research was to determine if the Northern Vigor® phenomenon, expressed as a combination of elevated crop yield and phytomedicinal quality in crops grown in northern latitudes, exists in narrow-leaved purple coneflower (Echinacea angustifolia DC.). In a 2-yr study, narrow-leaved purple coneflower was grown in three field sites in Saskatchewan, Canada (SK; Saskatoon, La Ronge, and Outlook) and one field site in Oregon, United States (Madras), to test the effects of latitude on root yield, phenolic, and alkylamide phytochemical markers. Roots harvested in 1999 (all three SK sites) and 2000 (two SK sites) had higher root biomass compared with roots harvested in Oregon. Root echinacoside and cynarin content were significantly higher in both years in the three Saskatchewan sites compared with Madras, whereas root chlorogenic acid content and total alkylamides were significantly higher in all three Saskatchewan sites in 1999. In 2000, root chlorogenic acid content and total alkylamides were higher in two of the three Saskatchewan sites compared with Madras. While Aster Yellows were prevalent in Echinacea in Saskatchewan, this disease did not significantly decrease root yield phenolic or phytochemical content. These data suggest that Saskatchewan has a competitive advantage in producing premium-quality narrow-leaved purple coneflower root in North America.