The Effect of Seed Source, Light during Germination, and Cold-moist Stratification on Seed Germination in Three Species of Echinacea for Organic Production

Abstract

<jats:p>Organic production of one of the most popular botanical supplements, <jats:italic>Echinacea</jats:italic>, continues to expand in the U.S. <jats:italic>Echinacea</jats:italic> seeds typically show a high degree of dormancy that can be broken by ethephon or gibberellic acid (GA), but these methods are currently disallowed in organic production. In order to determine the efficacy of nonchemical seed treatments, we evaluated the effect of varying seed source and supplying light, with and without cold-moist stratification, on seed germination of the three most important medicinal species of <jats:italic>Echinacea</jats:italic>, <jats:italic>E. angustifolia</jats:italic> DC<jats:italic>, E. purpurea</jats:italic> (L) Moench, and <jats:italic>E. pallida</jats:italic> (Nutt.) Nutt. Treatments included cold-moist stratification under 24 hours of light, 24 hours of dark, and 16/8 hours of light/dark to break seed dormancy. We found that germination was greater in the <jats:italic>E. purpurea</jats:italic> and <jats:italic>E. pallida</jats:italic> seeds from a commercial organic seed source compared to a public germplasm source. When seeds were not cold-moist stratified, 16 to 24 hours light increased germination in <jats:italic>E. angustifolia</jats:italic> only. <jats:italic>Echinacea angustifolia, E. purpurea</jats:italic>, and <jats:italic>E. pallida</jats:italic> seeds that were cold-moist stratified under 16 to 24 hours of light for 4 weeks had a significantly greater percentage and rate of germination compared to seeds germinated in the dark. Therefore, cold-moist stratification under light conditions is recommended as a method to break seed dormancy and increase germination rates in organic production of <jats:italic>Echinacea</jats:italic>.</jats:p>

Phytochemical localization and fungal inhabitants in the fruits of four Echinacea taxa

“…E. atrorubens var. paradoxa differs from the commercial species in that its phytochemicals, particularly alkylamides, are concentrated in the flower head, which could explain the discrepancy (Chen et al 2009 There have been several studies looking at the germination of Echinacea species and how it can be improved with various treatments (Chuanren et al 2004, Parmenter et al 1996, Romero et al 2005. In agreement with this study, untreated E. pallida var.…”

“…angustifolia germination rates can be as low as 0-5% but stratification treatments can improve germination to rates comparable to E. purpurea and E. pallida var. pallida (Chuanren et al 2004, Parmenter et al 1996, Romero et al 2005. To my knowledge, no papers have been published assessing the germination of E. atrorubens var.…”

Reduction of seed dormancy in Echinacea pallida (Nutt.) Nutt. by in-dark seed selection and breeding

“…It also leads to uniform stand establishment that better facilitates field management and the possibility of longer overall growing seasons (Taylor and Harman, 1990). In Echinacea , seed stratification under moist, cool conditions has been used to accelerate and synchronize germination (Romero et al, 2005) in addition to its use for dormancy breaking per se . Rapid, synchronized germination is also a beneficial outcome of our selection and breeding experiment.…”

“…Development of protocols to improve Echinacea seed germination has been extensive, involving the use of inorganic salts (Gao et al, 1998), growth regulators (Bishnoi et al, 2010; Pill and Haynes, 1996; Qu et al, 2004), cold, moist stratification (Bishnoi et al, 2010; Bratcher et al, 1993; Parmenter, 1996; Qu et al, 2004, Romero et al, 2005; Wartidiningsih et al, 1994) and mechanical scarification (Bishnoi et al, 2010; Feghahati and Reese, 1994; Sorenson and Holden, 1974). Without such treatments, Echinacea seeds (except for some commercial seed lots of E. purpurea ) tend to germinate poorly and/or erratically.…”

“…Of methods that do not involve synthetic chemicals, cold, moist stratification is time consuming, requiring several weeks under controlled conditions, and results have been uneven (Bratcher et al, 1993; Parmenter, 1996; Qu et al, 2004, Romero et al, 2005; Wartidiningsih et al, 1994). Light is another factor that can be effective in promoting Echinacea seed germination (Feghahati and Reese, 1994; Smith-Jochum and Albrecht, 1987), and has been used both during and following cold, moist stratification (Romero et al, 2005). It is important to note that any light requirements for seed germination present risks of seed desiccation and seed loss due to wind or bird predation when seeds are sown under field conditions with little or no covering (Qu et al, 2004).…”