tance of plant germplasm mandates the adoption of a new approach to systemwide management, and it offers two options for achieving this goal. It considers the more viable option to be the establishment of the NPGS as an independent agency within USDA's Office of Science and Education.

Germplasm includes older and current crop varieties, specialized breeding lines used to develop new varieties and hybrids, landraces of crops that have emerged over centuries of selection by farmers, wild plants related to individual crops, and mutant genetic stocks maintained for research, particularly when gathered together in organized collections of plants, seeds, or tissues. Germplasm collections can range from plants maintained in greenhouse or field plantings, to dried seeds in sealed envelopes held at low temperatures, to in vitro cultures of tissues or buds.

The phenomenal agricultural productivity of the United States has come from using germplasm to improve crops genetically. Examples include pest and disease resistance in tomatoes from obscure, wild Lycopersicon species related to the cultivated tomato and the derivation of modern corn and wheat from early landrace varieties introduced by Mexican Indians and European and Middle Eastern settlers, respectively. Modern high-yielding wheats are derived in part from semi-dwarf varieties introduced from Japan following World War II. Much of the germplasm in U.S. collections originated in other countries.

The viability of U.S. agriculture depends on a flow of enhanced crop varieties that can withstand pests, diseases, or climate extremes. The adaptability of pests and diseases, changes in agricultural practice, such as greater emphasis on the biological control of pests, and changes in consumer needs or preferences require the continuation of the varietal development process.

Genetic diversity is a natural resource. All nations share the responsibility for its management and the privilege of using it. Individuals, private organizations, and universities can contribute to the maintenance of germplasm, but the tasks of overseeing and managing genetic resources are clearly beyond the capacity of any individual or group. Coordination of the many and varied efforts in the United States, including international collaboration, must be through a national, government-supported, centrally managed program.

Germplasm activities in the United States have been largely driven by an unofficial policy of national self-sufficiency that calls for compre-

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)