Classification of seed dormancy and treatment of gibberellic acid to improve germination of arrowleaf balsamroot

With its perennial showy flower, soil-stabilizing taproot, and energy-rich winter foliage, arrowleaf balsamroot (Balsamorhiza sagittata (Pursh) Nutt. [Asteraceae]) has several traits that lend it to ornamental and conservation applications, if it can be propagated successfully and cost efficiently. Percent germination remains low, however, because of its unknown seed dormancy classification and dormancy-release mechanism. Based on a series of germination tests, seeds exhibit nondeep physiological dormancy, type 2; intermediate physiological dormancy, type 2; and deep physiological dormancy, types 1 and 3 according to the Baskin and Baskin (2004) classification. In the Schwienbacher and others (2011) reclassification, seeds exhibit the class and level, physiological deep dormancy. Gibberellic acid (GA3) followed by cold-moist incubation at 5 °C (41 °F) significantly increased percent final germination, with a maximum final germination of 81 ±2%.