List of contributors; 1. Genetic resources - the past ten years and the next O. H. Frankel and J. G. Hawkes; Part I. Genetic Variation in Plant Populations: 2. Population structure and the effects of breeding system S. K. Jain; 3. Population structure and the effects of isolation and selection A. D. Bradshaw; 4. Optimum sampling strategies in genetic conservation D. R. Marshall and A. H. D. Brown; 5. Sampling germplasm in a center of diversity: an example of disease resistance in Ethiopian barley C. O. Qualset; Part II. Exploration; Section 1. Exploration Targets: 6. Genetic resources survey as a basis for exploration O. H. Frankel; Section 2. Practical Problems in Exploration: 7. Seed crops J. R. Harlan; 8. Vegetatively propagated crops J. G. Hawkes; 9. Tree crops J. T. Sykes; Section 3. National and Regional Exploration Activities: 10. Recent plant exploration in the USA H. L. Hyland; 11. Plant exploration in the USSR D. D. Brezhnev; 12. Recent and proposed exploration activities of the Izmir Centre, Turkey H. A. Sencer; 13. Exploration and survey in rice T. T. Chang; 14. Potato collecting expeditions in Chile, Bolivia and Peru, and the genetic erosion of indigenous cultivars C. Ochoa; 15. Recent cocoa collecting expeditions J. Soria; Part III. Evaluation Problems: 16. The search for disease and insect resistance in rice germplasm T. T. Chang, S. H. Ou, M. D. Pathak, K. C. Ling and H. E. Kauffman; 17. Evaluation of sources of disease resistance A. Dinoor; 18. Evaluation of material for frost and drought resistance in wheat breeding V. F. Dorofeev; 19. The identification of high-quality protein variants and their use in crop plant improvement D. E. Alexander; 20. Screening for oils and fats in plants G. Robbelen; 21. Secondary metabolites and crop plants R. Henauer; Part IV. Conservation and Storage: 22. Problems of long-term storage of seed and pollen for genetic resources conservation E. H. Roberts; 23. Genetic maintenance of seeds in imbibed storage T. A. Villiers; 24. Some factors contributing to the survival of crop seeds cooled to the temperature of liquid nitrogen A. Sakai and M. Noshiro; 25. Meristem culture techniques for the long-term storage of cultivated plants G. Morel; 26. The problem of genetic stability in plant tissue and cell cultures F. D'Amato; 27. Technical aspects of tissue culture storage for genetic conservation G. G. Henshaw; 28. Possible long-term cold storage of woody plant material B. H. Howard; 29. The storage of germplasm of tropical roots and tubers in the vegetative form F. W. Martin; 30. Genetic reserves S. K. Jain; Part V. Documentation and Information Management: 31. Documentation for genetic resources centers D. J. Rogers, B. Snoad and L. Seidewitz; 32. Documentation and information requirements for genetic resources application G. N. Hersh and D. J. Rogers; Part VI. Genetic Resources Centres: 33. Crop germplasm diversity and resources in Ethiopia M. H. Mengesha; 34. A regional plan for the collection, conservation and evaluation of genetic resources E. Kjellqvist; 35. IRRI's role as a genetic resources center T. T. Chang, R. L. Villareal, G. Loresto and A. T. Perez; 36. Maize germplasm banks in the Western Hemisphere W. L. Brown; 37. Genetic resources centres - a co-operative global network O. H. Frankel; Index.