that cannot be reproduced because day-length or temperature requirements cannot be met in the United States. Some accessions requiring warm, short days are amenable to winter culture at facilities in Puerto Rico or St. Croix, but for other reasons cannot be grown at these sites. Some short-day beans, from the Regional Plant Introduction Station in Pullman, Washington, for example, will flower at these Caribbean stations, but native insects increase cross-pollination among accessions and the difficulty of maintaining genetic integrity. High-elevation materials often require cooler temperatures (especially cooler nights) than available in tropical or subtropical island habitats. Controlled greenhouse facilities have been used to meet some of these needs, but they are very costly. Controlled facilities do, however, provide security from the often unpredictable hazards (e.g., pests, disease, weather extremes, unanticipated pollinators) that can make field increase a risky endeavor. The need for an adequate population size to preserve genetic diversity can constrain the use of controlled environment facilities for regular regeneration.

Facilities at which short-day responsive plants can be grown and multiplied in the field should be found. They are required for a wide range of annual and perennial plants that must be regenerated, characterized, and evaluated. Field maintenance and growth would greatly increase the capacity for these activities over that of greenhouses. The site should be frost-free throughout the year, with low relative humidity, freedom from violent storms, and at a sufficient altitude to avoid extremes of heat. It must be accessible to irrigation and sufficiently isolated from general agriculture to provide a relatively disease-free environment. A site outside the United States that meets these requirements could be established by cooperation among USDA, USAID, and IBPGR. Adequate monitoring and precautions must be taken at such sites to prevent contamination of regenerated accessions with pests or pathogens that could be inadvertently spread when seed is distributed.

The United States also needs a facility located in an arid region, such as the drier desert southwest where pests and disease are typically less abundant. Cooperative agreements already provide for regenerating cotton and some small grains in this region. An NPGS site would be particularly valuable for maintaining selected accessions of sorghum, bean, grass, small grains, and jojoba.

The federal and state partnership for managing plant germplasm should be reappraised and reinforced.

Because it is sometimes difficult for ARS employees to supervise state

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)