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United States Department of Agriculture

Agricultural Research Service

Title: Overview and Agronomic Evaluation of the USDA Annual Medic Germplasm Collection

Authors
item Johnson, Richard
item Graves, Walter - RETIRED

Submitted to: Alfalfa Improvement Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 1998
Publication Date: N/A

Interpretive Summary: The USDA-ARS maintains a collection of medics consisting of 3,562 accessions representing 48 taxa. This genetic material has many potetial uses, especially as forage and cover crops in sustainable agricultural systems. Regeneration and evaluation has been completed on this collection at Riverside, CA. Currently over 90% of 3,562 medic accessions are available for distribution. Evaluation data is available on roughly two-thirds of the accessions in the collection and is available from the Germplasm Resources Information Network (GRIN). Individual accessions within species showed considerable variation, suggesting that selection within species appears possible.

Technical Abstract: The USDA-ARS maintains a collection of medics (Medicago sp.) consisting of 3,562 accessions representing 48 taxa. From 1987 to the present, regeneration and evaluation has been completed on this collection at Riverside, CA. Currently over 90% of 3,562 medic accessions are available for distribution. Evaluation data is available on roughly two-thirds of the accessions in the collection and is available from the Germplasm Resources Information Network (GRIN). Data for five agronomic factors was collected on over 2,000 accessions. A wide range of agronomic types were found within most species and eleven were compared in more detail. Canonical discriminate analysis was used to determine if distinct groupings would form using the evaluation data of eleven of the most potentially important species (M. italica, littoralis, lupulina, minima, murex, obicularis, polymorpha, rigidula, rugosa, scutellata, truncatula). Some separation among species was observed, especially between M. lupulina, M. polymorpha, and a grouping made up of M. scutellata and M. rugosa. For the remaining seven species, the means of the canonical functions were quite closely grouped and their standard deviations overlapped. The results suggested that the variability observed between many of the species was too small to allow distinct groupings. But since variation for the evaluation factors within species was high, selection within species for improved traits appears possible.

Last Modified: 8/22/2014
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