Monitoring moisture in the Millennium Seed Bank
The Royal Botanic Gardens (RBG) is using a Dewmet cooled
mirror dewpointmeter from Michell Instruments to monitor the
equilibrium relative humidity (ERH) levels, and therefore, moisture
status of seeds stored in the Millennium Seed Bank at
Wakehurst Place.
An important conservation and research facility, the Millennium Seed
Bank will house live seeds from an anticipated 10% of the world’s plant
species, enabling them to be stored long term in a state of suspended
animation.
Sponsored by the Millennium Commission, Orange plc and the Wellcome
Trust, the Millennium Seed Bank has been established in response to the
increasingly important role that seeds are playing in the conservation and
use of wild plants.
Extending the service offered by the RBG’s existing seed bank, the
new centre will prioritise the storage of those species, mainly from the
tropical drylands, that are currently under threat due to human
developments and deforestation, with the final aim of collecting
and preserving around 25,000 plant species by the year 2010.
As a further benefit, information gleaned from analysis of the seeds
will be incorporated into a comprehensive central database that, subject
to agreements, will be used to publicise the contents of the seed bank
to university departments, agricultural institutes and non-governmental
organisations working in the developing world.
In practice, seed samples collected from field trips or supplied by
scientists specifically for storage, are separated from the seed cases,
dried to 15% relative humidity and deep frozen for storage in air-tight
aluminium and glass containers at —20°C. The low moisture content
and temperatures slow down the rate at which the seeds lose their
ability to germinate, preserving the species for hundreds, and in some
cases, thousands of years.
To ensure that the seeds remain viable during storage, conditions
are carefully monitored and a number of seeds of each type are
periodically extracted and tested for germination to confirm that they
are still alive. Michell Instruments’ cooled mirror dewpointmeter, Dewmet,
has been specially modified to provide direct analysis of the equilibration
RH of the seeds samples, both prior to and during storage.
Dewmet provides a high accuracy of ±0.2°C dewpoint and 0.1°C gas
temperature across a measurement range of —50 °C to +85°C dewpoint
and —40 °C to +90°C ambient temperature. Combined with a fast
response speed of 1°C per second and zero drift, Dewmet ensures that
RH readings remain accurate over time.
Keith Manger, Laboratory Manager at Kew’s Seed Conservation
Department comments, “The Millennium Seed Bank is an important
resource in conserving the world’s plant species and offers us both
an insurance service should other conservation techniques not be
successful and a valuable information resource. Potentially,
Dewmet also provides us with a tool for the precise measurement of
seed moisture status in research studies of the role of water in seed
survival.”
For further information, please contact:-
Michell Instruments Limited at Nuffield Close, Cambridge, CB4 1SS. UK
Tel: 0800 975 4770 Fax: 01223 434895
email: info@michell.co.uk,
or visit the Michell Instruments web site at www.michell.co.uk
July 2000 - Ref: MI180
