Osmotic Priming or Chilling Stratification Improves Seed Germination of Purple Coneflower

in HortScience
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  • 1 Department of Horticulture and Landscape Architecture, University of Kentucky, Lexington, KY 40546

High germination seed lots of purple coneflower [Echinacea purpurea (L.) Moench] were evaluated for laboratory germination following osmotic priming or chilling stratification. Compared to nontreated seeds, osmotic priming at 25C in salts (KNO3 + K3PO4; 1:1, w/w) or polyethylene glycol 4000 (PEG) increased early (3-day) germination percentage at 27C of all seed lots, and improved total (10-day) germination percentage of low-germination seed lots. Total germination percentage was unaffected or increased by priming for 4 days compared to 8 days, and by priming at –1.0 MPa compared to –0.5 MPa (except for one low-germination seed lot). Chilling stratification in water at 5 or 10C increased early and total germination of all seed lots, except for that same lot, compared to nontreated seeds. Total germination percentage was unaffected or increased by stratification at 10C rather than at 5C. Neither extending stratification ≥20 days nor lowering osmotic potential with PEG during stratification improved total germination percentage.