, 214:156 | Cite as

Two contrasting laboratory methods improve Silphium integrifolium Michx. germination rate to agronomically acceptable levels

  • Stephan Reinert
  • Kennedy L. Money
  • Greta B. G. Rockstad
  • Nolan C. Kane
  • David L. Van Tassel
  • Brent S. HulkeEmail author


Organic dormancy, the inability to germinate under favorable conditions, is a common problem in many crop species and their wild relatives, leading to more variable emergence, plant density, and growth rates, thus increasing costs, and lowering yield. To overcome these problems, several different methods have been developed for various crop and model plants. However, in the emerging crop being bred from wild and semi-domesticated Silphium, no such method has been established thus far. The objective of this study was to identify a dormancy-breaking assay to increase the seed germination rate. Seeds of three different Silphium integrifolium Michx. genotypes were treated with five chemical and one cold treatment, and dried before or after the treatment at 27 °C or 40 °C. Untreated, dried seeds were taken as control. Seeds soaked for 24 h in a ethephon/potassium nitrate solution followed by a 72 h drying step at 40 °C showed an increase of germination to up to 90 ± 2% compared to control seeds (3 ± 0% and 5 ± 1%). We identified the minimum time frame of cold stratification needed to enhance seed germination in Silphium, and found that cold stratification was nearly as good as the chemical treatment. Our results provide two alternate ways to treat S. integrifolium seeds for breaking organic dormancy, which will help to facilitate future research in the Silphium domestication community. The fact that our optimal treatments were similar to protocols developed for sunflower suggests that these methods may also be applicable to many related economically important Asteraceae species.


Silphium Germination Ethephon Asteraceae Cold stratification Ethylene Helianthus Seed dormancy Sunflower 



The Authors would like to acknowledge Brian Smart and Zoe Portlas for critically reviewing the manuscript. We thank Jon Tetlie for his assistance in performing the germination protocol.


The Malone Family Land Preservation Foundation


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Copyright information

© This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply 2018

Authors and Affiliations

  1. 1.Ecology and Evolutionary Biology DepartmentUniversity of ColoradoBoulderUSA
  2. 2.Department of Plant SciencesNorth Dakota State UniversityFargoUSA
  3. 3.Department of Agronomy and Plant GeneticsUniversity of Minnesota Twin CitiesMinneapolisUSA
  4. 4.The Land InstituteSalinaUSA
  5. 5.USDA-ARS Red River Valley Agricultural Research CenterFargoUSA

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