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Annual Medicago Species Core
Collection. |
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The annual medics are endemic to the Mediterranean region of the world. There
are 34
recognized species of annual medics and 3159 accessions of the annual medics
in the US Plant
Introduction collection. |
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Karl Lesins Medicago
Collection |
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Although there is interest in the annual medics for use in sustainable
agricultural systems, the US
collection is under utilized due a lack of agronomic information. Development
of a core
collection may be a method of condensing the collection of agronomic data on
the available
germplasm to make it more accessible for utilization by breeders and
agronomists. A core
germplasm collection is a small collection that represents the maximum genetic
diversity with
minimum repetitiveness. During the summer of 1990 we grew 1220 accessions of
the annual
medics in the field at Beltsville, MD and evaluated them for 15 morphological
and agronomic
traits. |
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Evaluation in Beltsville, MD |
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Eleven different methods of determining a core collection were evaluated and
it was determined
that the core would be developed using the Relative Diversity method. The
Relative Diversity
method utilizes cluster analysis (an unweighted pair group method using
arithmetic averages) and
selects the number of accessionswithin each group based on the group's
relative phenotype or
genetic diversity (Diwan, McIntosh and Bauchan, 1995.)
The resultant 211 accessions, contains all 34 species and has one accession
per cluster within a
species (Diwan, N., Bauchan, G. R. and
McIntosh, M. 1994) (See
list). The core
collection was further evaluated in 1991 and 1992
in five locations (Beltsville, MD; Logan, UT; Pullman, WA; St. Paul, MN; and
Tucson, AZ) to
determine if there are genotype X environmental interactions and to allow
researchers and
interested individuals an opportunity to observe the annual
medics. |
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Evaluation in Logan, UT |
Australian Annual Medicago core collection
Collection. |
The largest collection of annual medics exists in Australia. The Australian
medic collection
contains over 21,000 accessions whereas the U. S. collection contains 3,000
accessions A core
collection has been designated for the Australian medic collections which is
composed of 1705.
See
list and Skinner, Bauchan, Auricht and Hughes, 1999 |