Effects of storage on seed dormancy and survivorship in black cohosh (Actaea racemosa L.) and goldenseal (Hydrastis canadensis L.)

Medicinal herbs indigenous to eastern deciduous forests are increasingly cultivated in forest gardens for economic and cultural purposes, yet little information is available on how post-harvest seed storage effects survivorship and germination. In this study, seeds of the medicinal woodland herbs, black cohosh (Actaea racemosa L.) and goldenseal (Hydrastis canadensis L.), were subjected to a factorial combination of storage conditions over a 360 d period to quantify seed survivorship and dormancy levels. Our results corroborate a prior study that indicates seeds of both species are morphysiologically dormant (MPD) and require a sequence of warm → cold temperatures for complete dormancy-break. Laboratory-stored seed populations removed at six different storage intervals and germinated over a range of thermoperiods in light and darkness failed to germinate, indicating that no seeds after-ripened in ambient (23°C) and cold (5°C) temperature storage. Seed germination percentages (80-90%) in H. canadensis remained relatively unchanged when laboratory-stored seed populations were moved through temperature sequences that broke dormancy with fresh seed. By contrast, storage at ambient and cold temperature for ≥ 270 d induced a deeper dormancy in viable seed populations of A. racemosa. Seed populations of H. canadensis lost viability by 360 d when stored at either ambient or cold temperatures whereas approximately 30% of A. racemosa seeds survived dry-storage for 360 d.