Year of Publication

2007

Document Type

Thesis

College

Agriculture

Department

Plant and Soil Science

First Advisor

Robert L. Geneve

Abstract

Inconsistent seed germination poses a problem for efficient seedling production of Echinacea species. Evidence suggests that ethylene can be effective for improving germination in Echinacea species. The objectives of this research were: to develop an ethylene pre-germination treatment that enhances germination in Echinacea species that is retained following drying and storage, and to determine if the ethylene effect on enhanced germination was an important mode of action for dormancy release. Four species of Echinacea (E. purpurea, E. tennesseensis, E. angustifolia and E. simulata) treated with 1-aminocyclopropane-1-carboxylic acid (ACC) or ethephon resulted in faster and generally higher germination. Pre-treatment of seeds with ACC or ethephon followed by drying was as effective as chilling stratification for enhancing germination depending on the species. While ethylene pretreatments did increase germination to some extent depending on species, it was concluded that 60-day stratification alone was a more commercially-viable treatment. Ethylene production or perception was not necessary for germination in untreated or stratified seeds as shown by aminoethoxyvinylglycine (AVG), silver thiosulfate (STS), and 1-methylcyclopropene (MCP) treatments. Both stratification and ACC treatment reduced Echinacea seed sensitivity to ABA and could be a common mechanism for enhanced germination. However, it does not appear that the increased germination seen after stratification was mediated through ethylene production because final germination percentages were generally unchanged following inhibition of ethylene production or action. In contrast, inhibition of ethylene production and perception reduced early 3-day germination suggesting that ethylene was more involved in seed vigor than final germination. It was determined that there is no physiological significance of ethylene for dormancy release in these Echinacea species.

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