NPGS, particularly those received before 1978. While passport data do exist for many accessions, the NPGS has been slow in adding this information to its computerized database.

Characterization involves the assessment of a varying number of descriptors ranging from morphological to biochemical. These descriptors, intended to describe an accession in relation to others in the collection, are determined by crop advisory committees and curators. The information can be gathered by the curators of active collections as materials are regenerated or assessed by cooperating scientists during evaluation for resistance to disease, environmental responses, or other traits. The gathering of crop descriptor data is an important part of the work of regional stations, repositories, and commodity collections because such data better define germplasm holdings and aid re-identification during regeneration.

Evaluation is a lengthy, often repetitive process of examining accessions for traits of significance to potential users. Screening for disease resistance is an example. It may take many years to test all of the accessions for a very large collection in a sufficiently wide range of environments. Although preliminary evaluation for genetically stable traits is generally considered an NPGS activity, more detailed evaluation for characters such as disease resistance or production qualities is generally part of the research that accompanies a breeding program. In a few cases, such as alfalfa at the western regional station, NPGS sites have funded researchers at other locations to conduct evaluations. Private companies and other users of NPGS germplasm also evaluate material, and the NPGS has occasionally provided funds for evaluating certain traits.

The Soil Conservation Service (SCS) also cooperates with the NPGS through a memorandum of understanding with the ARS to perform evaluations on certain materials. One purpose of the SCS is to foster acquisition, evaluation, and distribution of plants important to soil and water conservation.

The usefulness of new accessions depends on the user being able to retrieve information about them. In 1977 ARS recommended setting up a central repository for genetic resources information with standardized crop descriptors that would improve the management of NPGS collections (Mowder and Stoner, 1989). The Germplasm Resources Information Network manages all of the data associated with acquisition, evaluation, regeneration, inventory, and other records of the NPGS collections. It

Front Matter (R1-R16)

Executive Summary (1-20)

1 Managing Crop Genetic Resources (21-42)

2 Elements of the National Plant Germplasm System (43-86)

3 Administration of the National System (87-106)

4 Prescription for Effectiveness (107-144)

References (145-148)

Glossary (149-153)

Abbreviations (154-155)

Authors (156-160)

Index (161-173)