Effects of seed age and dormancy-breaking treatments on the viability and germination of the Gulf of Saint Lawrence aster (Symphyotrichum laurentianum)

Abstract

The Gulf of St. Lawrence aster, Symphyotrichum laurentianum (Fernald) G.L.Nesom (Asteraceae), is a threatened halophyte found only in parts of Atlantic Canada, and seeds are being stored in the seed bank located at the University of Prince Edward Island. It is important to assess the quality of the seeds in storage to ensure their usefulness in the conservation of the species. We tested the effects of seed age on the viability and germination potential of seeds currently held in the seed bank and the effect of dormancy-breaking treatments on germination. Seeds produced in six different years were tested using the tetrazolium test and standard germination tests. Our results show high viability for seeds from all years but relatively low germination, with no clear relationship between germinability and seed age, indicating that the potential for these seeds to germinate may depend on other factors. To test the usefulness of dormancy-breaking treatments, seeds were subjected to a cold moist treatment or a hormone treatment of gibberellic acid, kinetin, or a combination of the two. All of the treatments significantly enhanced germination by comparison with the control, with the combined treatment of gibberellic acid and kinetin being the most effective at stimulating germination.