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Maximising Longevity in Orchids and other Socio-economically Important, but Potentially Short-lived, Species

Seed of Dactylorhiza fuchsia (Orchidaceae) seeds, which show sub-zero temperature sensitivity

This project is one of a series in the theme 'Preservation technology'.

The Conventional on Biological Diversity and the Global Strategy for Plant Conservation emphasise the importance of conserving species of socio-economic value, which are under threat due to, inter alia, over-harvesting, e.g. Warburgia salutaris.  Whilst the main crops are protected in a global network of crop gene banks affiliated to the Future Harvest Centres, the ex situ conservation of species of lesser global value, but higher local value, is less well supported. Often these species have seeds whose storage behaviour is uncertain due to data deficiency. This project aims to establish the ex situ seed conservation potential of a range of socio-economic (non-crop) species. The main objective has been to clarify conservation options for dry seed storage. However, two inter-related concerns about storage environment (and pre-treatments) have also been addressed: 1) the possible detrimental impact of ultra-drying on seed longevity; and 2) the prospect that the optimum moisture content for seed storage shifts significantly at cryopreservation temperature. 

We have shown that: 1) ultradrying has no long-term impact on the performance of seeds of the cactus Mamillaria supertexta when stored for 6 years  at –20°C; and 2) that contrary to predictions, low humidity seeds of hybrid Salix and orchids (with their fungal symbionts) tolerate cryopreservation as well as or better than storage at –20°C. The results support the notion that cryopreservation can and should be used for the conservation of seeds that are: 1) inherently / potentially short-lived; 2) in limited supply; 3) desiccation sensitive. In addition, storage options have been explored for a number of multi-purpose tree species, including: Dovyalis caffra, Kigelia africana, Lannea microcarpa, Prunus africana.  Finally, a synthesis of comparative seed biology for 52 tropical tree species, from the Americas to China, has been published (see Annex)

One of the key future challenges is the establishment of a global network of orchid seed banks to conserve species that are threatened with extinction due to habitat fragmentation, climate change and / or overharvesting. See Annex 1 for 11 papers emanating from this project.

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