Maximising Seed Quality: Maturity and Post-harvest Studies
Seeds in fruit capsule of Iris pseudacorus (Iridaceae)
Research carried out in our laboratories and elsewhere has shown that the relative timing of the acquisition of desiccation tolerance varies between species. Coupled with developmental variation at the time of seed collection, this presents a potentially serious constraint to effective seed conservation. Our detailed studies of seed development in selected species, in collaboration with international partners, has led to the development and routine adoption of practical methods for maximising the quality of conservation collections. However, the number of species studied in detail is very small and it is vital that we continue to capture data from the application of post-harvest ripening treatments in order to broaden our understanding. Analysis of pre- and post-storage seed viability data also enables us to identify unusual behaviour requiring further investigation.
An example, of such behaviour first emerged in routine MSB seed viability tests on the British native woodland species Anemone nemorosa. Through a combination of laboratory and field-based experiments, using seed collected from a population local to Wakehurst Place we have confirmed that in this species, embryo development and hence tolerance to desiccation and storability is incomplete at the time of natural dispersal. Anatomical and physiological data have also shown that desiccation tolerance is lost soon after it is acquired as the embryos continue to grow inside the seeds. This evidence has enabled us to generate novel ideas concerning the developmental pathway for seeds with underdeveloped embryos which challenges one of the widely supported classes of seed dormancy.
In view of the obvious practical implications of such findings, we are currently extending this research to investigate a wider range of species with comparable structural and ecological traits. Target families include the Amaryllidaceae, Berberidaceae and Apiaceae. This work links closely with studies of comparative longevity (orthodox seeds) and the role of 'underdeveloped' embryos in germination / dormancy problems.
Project partners and collaborators
University of Pavia
Department of Environment and Conservation, WA
School of Agriculture, Policy and Development, University of Reading
Key papers published since 2006:
Hay, F., Klin, J. & Probert, R. (2006). Can a post-harvest ripening treatment extend the longevity of Rhododendron L. seeds. Scientia Horticulturae. 111: 80-83.
Probert, R., Adams, J., Coneybeer, J., Crawford, A. & Hay, F. (2007). Seed quality for conservation is critically affected by pre-storage factors. Australian Journal of Botany 55: 326-335.
Ali, N.S., Probert, R.J., Hay, F.R., Davies, H. & Stuppy, W. (2007). Post-dispersal embryo growth and acquisition of desiccation tolerance in Anemone nemorosa L. seeds. Seed Science Research 17(3): 155-165.
Butler, L.H., Hay, F.R., Ellis, R.H. & Smith, R.D. (2009). Post-abscission, pre-dispersal seeds of Digitalis purpurea remain in a developmental state that is not terminated by desiccation ex planta. Annals of Botany 103: 785-794.
Hay, F.R., Smith, R.D., Ellis, R.H. & Butler, L.H. (2010). Developmental changes in the germinability, desiccation tolerance, hardseededness, and longevity of individual seeds of Trifolium ambiguum. Annals of Botany 105:1035-1052.
Newton, R.J. (2011). Development, Dormancy, Germination and Ex-situ Survival of Seeds of Selected Amaryllidaceae Species. PhD Thesis, University of Reading, Reading, UK.