Comparative Longevity (Orthodox Seeds)

Standard seed ageing protocol equipment

This project is one of series in the theme of Preservation Technology.

It is well known that seeds from different species show wide variation in longevity during dry-storage. In the seed bank, where seeds are stored at -20°C after drying to 15%RH at 15°C, seeds from some species may remain viable for hundreds of years whereas seeds from other species may only survive a few years at best. This has implications for the management of the collections e.g. how often re-testing should be carried out, and perhaps in deciding whether conventional seed banking is an appropriate method of conservation for some, extremely short-lived species.

We have been testing seed longevity using a standard rapid ageing protocol for a number of years. For collections with large numbers of seeds, a sample of 600 is removed from storage and aged at 60% RH and 45°C; samples are taken at regular intervals and a germination test carried out. Probit analysis is carried out on the germination data in order to model the survival curve and rank the species according to the relative longevity.

One hundred and ninety five species from 71 families have been included in the study and an analysis of comparative longevity in relation to factors such as ecology, seed structure and climate of origin has been carried out. Our study has shown that species with small embryos from the cool moist regions are likely to be shorter lived than species with large embryos from warm dry regions. We have also shown that species in certain genera are consistently short-lived e.g. Primula, Gentiana and Rhododendron.