Resources Laboratory (NGRL) at the Agricultural Research Service's Beltsville, Maryland, area.

Although plant exploration is an important part of the activities of the NPGS, the bulk of its collections have been acquired through exchange. Germplasm received from other collections worldwide accounts for an estimated 75 percent of acquisitions (S. Dietz, U.S. Department of Agriculture, personal communication, June 1989).

Not all of the germplasm that enters the United States comes in through the PIO. University researchers, botanical gardens and arboreta, companies, and private individuals all import plants and seed. Much of this material may not be duplicated or documented in NPGS collections.

Collections of unique germplasm, much of it privately held and not fully represented in the NPGS, form a considerable reservoir of diversity (Office of Technology Assessment, 1985). For example, groups such as the Seed Savers Exchange maintain heirloom or older varieties of vegetables, fruit, and flowers and distribute them primarily to individuals for personal use rather than for breeding new cultivars (Office of Technology Assessment, 1985; Shell, 1990). Their holdings are generally not part of NPGS collections and are not documented by it.

The PIO is responsible for cataloging incoming germplasm accessions, assigning plant introduction (PI) numbers, and distributing new acquisitions to appropriate curators. The PIO publishes an annual inventory, listing the materials that have been assigned PI numbers (e.g., U.S. Department of Agriculture, 1988a,b), and coordinates germplasm exchanges.

The PIO may receive germplasm entering the United States for transfer to the appropriate NPGS site or record that a particular site has received such materials. All documentation for accessions is verified at the PIO. A PI number is assigned by the NGRL once passport data are verified. The PIO then distributes the material to appropriate sites.

The office also monitors some of the germplasm that enters the United States through avenues outside the NPGS (e.g., industry, botanical gardens, researchers), especially those plants or seeds receiving the attention of plant quarantine. If any of these latter materials are of importance to the NPGS, the importer is contacted by the PIO and invited to provide samples to the appropriate NPGS site or collection.

With the aid of the National Program Staff of the ARS, PI numbers are also assigned to new crop varieties, parental and advanced breeding

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)