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Understanding Global Trends in the Use of Wheat Diversity and International Flows of Wheat Genetic Resources

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  • Smale, Melinda

Abstract

This paper discusses the centers of origin and diversity for bread wheat; sketches historical patterns in the sources and use of wheat genetic resources in modern plant breeding; identifies and compares indicators of genetic diversity used by social and biological scientists; reviews the relationship of wheat genetic diversity to yield stability and vulnerability to disease; develops a profile of the structure of genetic variation in wheat in the developing world today; and investigates how scientific plant breeding has influenced the structure of genetic variation among the major bread wheats grown in developing countries. Modern plant breeding appears to have contributed to genetic variation in several ways. The number of different landraces in pedigrees has steadily increased over the past 30 years, and the geographical origins of the landraces have broadened. The pedigree complexity of the more successful cultivars planted in the developing world has grown over time. Yield stability, both in terms of the performance of individual lines and in terms of regional yields, on farms, appears to have increased in the past decades. The diversity that confers resistance to the wheat rusts has also increased. Diversity over space and time varies among regions of the developing world. Spatial diversity, measured as the percentage area sown to leading modern cultivars, is lowest in West Asia and highest in Mexico/Guatemala. Temporal diversity is highest in Mexico/Guatemala, lowest in North Africa, and also fairly low in South Asia. However, both spatial and temporal diversity are fairly high for many developing countries compared to some of the major industrialized producers, such as Canada. Latent diversity, calculated from pedigree analysis, is fairly high across the developing world and does not appear lower than in the major industrialized wheat producers. Genetic distance measures calculated from genealogies demonstrate the comparative diversity among the top 10 bread wheats grown in West Asia and the marked similarity of wheats grown in Mexico/Guatemala and Canada. Numerous socioeconomic factors, which future research must examine more closely, have shaped the structure of genetic variation in farmers� fields. These factors are related to the adoption and diffusion of new varieties and include pricing policies for seed and associated inputs, and the structure of the seed multiplication and distribution system.

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Bibliographic Info

Paper provided by CIMMYT: International Maize and Wheat Improvement Center in its series Economics Working Papers with number 7670.

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Date of creation: 1996
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Handle: RePEc:ags:cimmew:7670

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Keywords: Crop Production/Industries;

References

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  1. Weitzman, M.L., 1991. "On Diversity," Harvard Institute of Economic Research Working Papers 1553, Harvard - Institute of Economic Research.
  2. A. J. Singh & D. Byerlee, 1990. "Relative Variability In Wheat Yields Across Countries And Over Time," Journal of Agricultural Economics, Wiley Blackwell, vol. 41(1), pages 21-32.
  3. Cuddy, John D A & Della Valle, P A, 1978. "Measuring the Instability of Time Series Data," Oxford Bulletin of Economics and Statistics, Department of Economics, University of Oxford, vol. 40(1), pages 79-85, February.
  4. Brush, Stephen B. & Taylor, J. Edward & Bellon, Mauricio R., 1992. "Technology adoption and biological diversity in Andean potato agriculture," Journal of Development Economics, Elsevier, vol. 39(2), pages 365-387, October.
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Citations

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Cited by:
  1. Brennan, John P. & Bialowas, Adam, 2001. "Changes in Characteristics of NSW Wheat Varieties, 1965-1997," Research Reports 28003, New South Wales Department of Primary Industries Research Economists.
  2. Traxler, Greg & Pingali, Prabhu L., 1999. "International Collaboration in Crop Improvement Research: Current Status and Future Prospects," Economics Working Papers 7668, CIMMYT: International Maize and Wheat Improvement Center.
  3. Rosegrant, Mark W. & Ringler, Claudia, 1997. "World food markets into the 21st century: environmental and resource constraints and policies," Australian Journal of Agricultural and Resource Economics, Australian Agricultural and Resource Economics Society, vol. 41(3), September.
  4. Negassa, Asfaw & Hellin, Jonathan & Shiferaw, Bekele A., 2012. "Determinants of Adoption and Spatial Diversity of Wheat Varieties on Household Farms in Turkey," Socioeconomics Program Working Papers 147106, CIMMYT: International Maize and Wheat Improvement Center.
  5. Heisey, Paul W. & Edmeades, Gregory O., 1999. "Cimmyt 1997/98 World Maize Facts And Trends; Maize Production In Drought-Stressed Environments: Technical Options And Research Resource Allocation," Facts and Trends/Overview and Outlook 9369, CIMMYT: International Maize and Wheat Improvement Center.
  6. Heisey, Paul W. & Lantican, Maximina A. & Dubin, H. Jesse, 2002. "Impacts of International Wheat Breeding Research in Developing Countries, 1966-97," Impact Studies 7653, CIMMYT: International Maize and Wheat Improvement Center.
  7. Dubin, H.J. & Brennan, John P., 2009. "Combating stem and leaf rust of wheat: Historical perspective, impacts, and lessons learned," IFPRI discussion papers 910, International Food Policy Research Institute (IFPRI).
  8. Carew, Richard, 2000. "Pricing To Market Behavior: Evidence From Selected Canadian And U.S. Agri-Food Exports," Journal of Agricultural and Resource Economics, Western Agricultural Economics Association, vol. 25(02), December.
  9. Johnson, N. L. & Pachico, D. & Voysest, O., 2003. "The distribution of benefits from public international germplasm banks: the case of beans in Latin America," Agricultural Economics, Blackwell, vol. 29(3), pages 277-286, December.

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