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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.

Suggested Citation

  • Smale, Melinda, 1996. "Understanding Global Trends in the Use of Wheat Diversity and International Flows of Wheat Genetic Resources," Economics Working Papers 7670, CIMMYT: International Maize and Wheat Improvement Center.
  • Handle: RePEc:ags:cimmew:7670
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    File URL: http://purl.umn.edu/7670
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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. 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.
    4. Swanson, Timothy, 1997. "The Management of Genetic Resources for Agriculture: Ecology and Information, Externalities and Policies," 1997 Conference, August 10-16, 1997, Sacramento, California 197041, International Association of Agricultural Economists.
    5. 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.
    6. 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.
    7. 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.
    8. 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.
    9. 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).
    10. 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.
    11. Mintewab Bezabih & Remidius Ruhinduka & Mare Sarr, 2016. "Climate change perception and system of rice intensification (SRI) impact on dispersion and downside risk: a moment approximation approach," GRI Working Papers 256, Grantham Research Institute on Climate Change and the Environment.

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    Crop Production/Industries;

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