Rehydration / Priming Treatment Effects on Seed Quality (Project completed 2010)

Rehydration priming: dissected seed capsule of Digitalis purpurea

Seed priming - a controlled hydration treatment whereby seeds are allowed to take up water but not reach full hydration - is used by the seed industry to improve seed quality traits such as speed and uniformity of germination and seedling vigour. Priming has also been shown to improve the subsequent longevity of Ranunculus sceleratus seeds, although for many other species, longevity is impaired. One aspect of this project is to screen other species, in particular those of the Ranunculus genus, for comparative longevity before and after priming in order to see whether seeds from other species would benefit from such a treatment prior to long-term storage in the Seed Bank.

The positive effect of priming on quality traits such as rate and uniformity of germination is usually attributed to the initiation of repair processes which occur in the early stages of germination. Priming is usually carried out on dry seeds and the rehydration solution is typically one of polyethylene glycol at -1.5 MPa. A second aspect of this project is to determine the optimum osmotic potential / RH for rehydration of freshly harvested but partially dried seeds of Digitalis purpurea and to try and determine whether these rehydration treatments constitute continuation of maturation events or repair processes associated with germination events.