IMPACTS OF INTERNATIONAL MAIZE BREEDING RESEARCH IN DEVELOPING COUNTRIES, 1966-98

This report, which updates and extends the findings of an earlier CIMMYT study published in 1994, documents the impacts of international maize breeding research in the developing world. Covering the period 1966-98, the report reviews public and private investment in maize breeding research, describes the products of public and private maize breeding programs, estimates farm level adoption of modern varieties (MVs), and estimates the gross value of additional grain production attributable to international breeding efforts. Although private companies have greatly increased their investment in maize breeding research in recent years, public maize breeding programs still play an important role, especially in breeding for subsistence-oriented farmers. Seed sales data show that the maize seed industry in many developing countries has effectively been privatized and that hybrid seed sales now dominate sales of all other seed types. The area planted to MVs continues to expand at an impressive rate. Maize MVs are currently grown on at least 58.8 million ha in developing countries, including at least 21.2 million ha planted to MVs that contain CIMMYT germplasm. The gross value of additional grain production attributable to the adoption of maize MVs in developing countries is estimated to range from US$3.7 million to US$ 11.1 billion per year. Analysis of varietal pedigrees shows that breeders in both the public and private sectors have made extensive use of CIMMYT germplasm. Over 54% of publicly bred MVs released in the developing world since 1966 have contained CIMMYT germplasm. The pedigrees of many privately bred cultivars are confidential, but CIMMYT germplasm was present in 58% of MVs developed by private breeding programs being sold in the late 1990s for which pedigree information is available. The gross benefits attributable to CIMMYT's maize breeding program are estimated to range from US$167 million to US$ 1.5 billion per year.Productivity Analysis,

Existence and uniqueness theorems for massless fields on a class of spacetimes with closed timelike curves

We study the massless scalar field on asymptotically flat spacetimes with closed timelike curves (CTC's), in which all future-directed CTC's traverse one end of a handle (wormhole) and emerge from the other end at an earlier time. For a class of static geometries of this type, and for smooth initial data with all derivatives in $L_2$ on {\cI}^{-}, we prove existence of smooth solutions which are regular at null and spatial infinity (have finite energy and finite $L_2$-norm) and have the given initial data on \cI^-. A restricted uniqueness theorem is obtained, applying to solutions that fall off in time at any fixed spatial position. For a complementary class of spacetimes in which CTC's are confined to a compact region, we show that when solutions exist they are unique in regions exterior to the CTC's. (We believe that more stringent uniqueness theorems hold, and that the present limitations are our own.) An extension of these results to Maxwell fields and massless spinor fields is sketched. Finally, we discuss a conjecture that the Cauchy problem for free fields is well defined in the presence of CTC's whenever the problem is well-posed in the geometric-optics limit. We provide some evidence in support of this conjecture, and we present counterexamples that show that neither existence nor uniqueness is guaranteed under weaker conditions. In particular, both existence and uniqueness can fail in smooth, asymptotically flat spacetimes with a compact nonchronal region.Comment: 47 pages, Revtex, 7 figures (available upon request

Adoption, Management, and Impact of Hybrid Maize Seed in India

This paper presents results of a 1995 survey of 864 maize-growing households in six states that account for more than 70% of India's maize area: Andhra Pradesh, Bihar, Karnataka, Madhya Pradesh, Rajasthan, and Uttar Pradesh. The current adoption of improved open-pollinated maize varieties (OPVs) and hybrids is quantified, the relationship between adoption of improved germplasm and use of improved crop management practices is examined, the economic impacts of adoption are estimated, farmers' seed procurement and management practices are described, and implications for maize research and development policy are discussed. On the whole, the survey results confirm that India's national maize seed industry is expanding rapidly. Since seed policy reforms were introduced in the late 1980s, the area planted to improved OPVs and hybrids has grown rapidly, and adoption of improved germplasm has fueled important changes in farmers' crop management practices. However, special policy measures may be needed to ensure that the benefits of improved germplasm are widely shared, such as the introduction of targeted input subsidies designed to reduce the cost of adopting improved seed and complementary inputs, government investment in irrigation infrastructure to reduce production risk in drought-prone environments, and market development initiatives to provide small-scale producers with access to stable and reliable outlets where they can sell surplus grain.Crop Production/Industries,

PRACTICAL CHALLENGES TO ESTIMATING THE BENEFITS OF AGRICULTURAL R&D: THE CASE OF PLANT BREEDING RESEARCH

Interest in the economics of plant breeding first emerged during the late 1960s and early 1970s following the well-known green revolutions in wheat and rice. Since that time, few branches of agricultural research have been subjected to as much scrutiny as plant breeding. Impacts assessment studies consistently conclude that the economic benefits generated by successful plant breeding programs are large, positive, and widely distributed. Case studies repeatedly find that investment in crop genetic improvement generates attractive rates of return compared to alternative investment opportunities. Similarly, case studies consistently show that the welfare benefits resulting from the adoption of modern varieties (MVs) are broadly shared by producers and consumers in both favored and marginal environments. Swayed by the large body of empirical evidence that supports these findings, governments, lending agencies, philanthropic organizations, and private corporations have invested millions in plant breeding research. But how reliable are the results of studies that estimate the benefits of plant breeding research? Are the methods used to conduct such studies theoretically sound? And are the data sufficiently complete and accurate? This paper reviews methods used to estimate the benefits of plant breeding research and discusses methodological issues and practical challenges that often receive inadequate attention in applied impacts work. Our goal is not to question the validity of the broad conceptual frameworks used to estimate the benefits of plant breeding research (e.g., economic surplus approach, production function approach). Nor is it our intention to examine theoretical issues that complicate research evaluation in general. Rather, the objectives of the paper are to examine problems that may arise during empirical evaluation of plant breeding research, to discuss what can happen if those problems are ignored or overlooked, and to propose workable solutions. The problems that affect the empirical evaluation of plant breeding research can be grouped into three general categories: measuring the adoption of MVs; estimating the benefits associated with adoption of MVs; and assigning credit for plant breeding research. In principle, estimating the area planted to MVs should be relatively easy. In practice, it is often very difficult. Important issues in estimating the benefits associated with MV adoption include the relationship between experimental and farm level yields; the relative effects of improved germplasm and improved crop management practices; maintenance research; non-yield benefits; and constructing counterfactual scenarios. The existence of spillovers in plant breeding research increases the overall benefits generated by the global plant breeding system, but it also complicates the task of assigning credit among individual breeding programs. CIMMYT researchers, working in collaboration with colleagues from national agricultural research organizations, have conducted a series of studies designed to document and quantify the impacts of international maize and wheat breeding research. Drawing on lessons learned from the CIMMYT studies, each of these three sets of problems that can affect the empirical evaluation of plant breeding research are discussed in detail, and practical guidelines are presented to help those interested in conducting applied impacts studies avoid common pitfalls that if ignored may lead to incorrect empirical results.Research and Development/Tech Change/Emerging Technologies,

HOW DOES GENDER AFFECT THE ADOPTION OF AGRICULTURAL INNOVATIONS? THE CASE OF IMPROVED MAIZE TECHNOLOGY IN GHANA

Why do men and women adopt agricultural technologies at different rates? Evidence from Ghana suggests that gender-linked differences in the adoption of modern maize varieties and chemical fertilizer are not attributable to inherent characteristics of the technologies themselves but instead result from gender-linked differences in access to key inputs.Research and Development/Tech Change/Emerging Technologies,

FACTORS EXPLAINING THE DIFFUSION OF HYBRID MAIZE: EVIDENCE FROM LATIN AMERICA AND THE CARIBBEAN IN SUPPORT OF THE LIFE CYCLE THEORY OF SEED INDUSTRY DEVELOPMENT

Factors affecting the diffusion of hybrid maize are explored using a unique data set from 18 countries in Latin America and the Caribbean. Our findings not only validate the conventional profitability-based explanations of farmer adoption behavior, but also confirm the importance of supply-side factors, providing empirical support for the life cycle theory of seed industry development.Crop Production/Industries,

Genetic Change in Farmer-Recycled Maize Seed: A Review of the Evidence

Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Impacts of International Wheat Breeding Research in the Developing World, 1988-2002

Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,