Influence of harvest time on quality and marketability of commercially important Echinacea spp.
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In late 90’s Echinacea, particularly Echinacea angustifolia, has become a lucrative medicinal root crop on the prairies. In the absence of well substantiated and reliable information on optimal time to harvest, roots are harvested in the fall of the 3rd or 4th year of production. The objective of this study was to determine the influence of three harvest times, spring, mid-summer and fall on accumulation of compounds believed to be responsible for the immunostimulatory activity of Echinacea. Phenolic glycosides (echinacoside in E. angustifolia and chicoric acid in E. purpurea) (1), alkylamides (2), and polysaccharides (3), were the three classes of natural compounds used for the phytochemical quality assessment in this study. Results indicated that root of 3-year old E. angustifolia plants harvested in the fall contained significantly higher content of polysaccharides, slightly higher content of echinacoside and slightly lower content of total alkylamides than roots collected in spring and summer. Also, roots of 2-year old plants were significantly higher in echinacoside and total alkylamides and significantly lower in polysaccharides than their 3-year counterpart irrespective of harvest time. Roots of 4-year old E. purpurea harvested in the fall contained higher amount of chicoric acid than roots harvested in spring and mid-summer. Given that echinacoside content is presently used by herb industry as an indicator of crop quality (and price), and for standardization of botanical preparations (typically 4%), we also determined the distribution of echinacoside and cynarin in fall harvested E. angustifolia root system. Both compounds were found to accumulate in greater quantities in small rootlets and root crowns than in main tap roots suggesting that phytomedicinal quality and market value are greatly dependent on the harvesting method. Other aspects of cultivation with implications on marketability of Echinacea are also discussed.
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