Alex Seglias, Denver Botanic Gardens
Plant biodiversity is being lost at an accelerated rate. To conserve native plants, many institutions are turning towards ex situ conservation methods, such as storage in seed banks. However, not all seeds are able to survive in seed bank conditions or they may be short-lived. Alpine species in Italy and Australia have been shown to lose viability at a quicker rate in seed banks compared to low-elevation species. To understand if alpine species from the Rocky Mountains of Colorado exhibit this same pattern, I used accelerated ageing experiments to simulate storage in a seed bank and expedite loss of viability. Ten samples of 50 seeds for four species (Castilleja puberula, Heterotheca pumila, Physaria alpina, and Saussurea weberi) were rehydrated in a dark incubator at 20°C and 47% humidity for two weeks. Following rehydration, the seeds were placed in a drying oven at 45°C and 60% humidity to age the seeds at various intervals of time. Following the ageing process, the seeds were placed into previously determined germination conditions (stratification followed by incubation at 20/10°C for one month). All species had P50 (time to 50% germination) values of <13.7 days, which is the threshold to consider a species short-lived in seed banks. These results suggest that we can’t haphazardly store seeds and assume that all species will survive for decades in seed banks. Rather, we need to assess what environmental and evolutionary conditions might preclude a species from being long-lived in storage and determine measures to mitigate loss of viability over time.