DEVELOPING A CORE COLLECTION OF ANNUAL MEDICAGO SPECIES

A core collection is a subset of a large germplasm collection that con tains accessions chosen to represent the genetic variability of the ge rmplasm collection. The purpose of the core collection is to improve m anagement and use of a germplasm collection. Core collections are usua lly assembled by grouping accessions and selecting from within these g roups. The objective of this study was to compare 11 methods of assemb ling a core collection of the U.S. National collection of annual Medic ago species. These methods differed in their use of passport and evalu ation data as well as their selection strategy. Another objective was to compare core collections with sample sizes of 5%, 10% and 17% of th e germplasm collection. Core collections assembled with evaluation dat a and cluster analysis better represented the germplasm collection tha n core collections assembled based solely on passport data and random selection of accessions. The Relative Diversity and the logarithm meth ods generated better core collections than the proportional method. Th e 5% and 10% sample size core collection were judged insufficient to r epresent the germplasm collection.