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Dimensions of Diversity in Modern Spring Bread Wheat in Developing Countries from 1965

^a International Plant Genetic Resources Institute (IPGRI), Rome, International Food Policy Research Institute (IFPRI), 2033 K St. N.W., Washington, DC 20006
^b International Maize and Wheat Improvement Center (CIMMYT), km 45 Carretera Veracruz, Texcoco, Mexico

View larger version (18K): [in a new window]   Fig. 1. Average coefficient of parentage of cultivars of spring bread wheat grown in the developing world in 1997, by area class. Calculated from 1997 Global Wheat Impacts survey data and CIMMYT Wheat Pedigree Management System. Note that classes are defined in order to assure COP matrices of equal size. About 300 cultivars for which pedigree information is known are included.

View larger version (14K): [in a new window]   Fig. 2. Landrace ancestors in spring bread wheat cultivars released by developing countries, 1966 through 1997. Calculations based on CIMMYT 1997 Global Wheat Impacts survey data and pedigree information in CIMMYT Wheat Pedigree Management System. Data were available for 1162 (included here) of the 1749 spring bread wheat cultivars recorded (in the survey data) as released during these years. Coverage is less complete for China and for wheats released in the last few years.

View larger version (32K): [in a new window]   Fig. 3. Principal components analysis of 27 CIMMYT spring bread wheat lines released from 1962 to 1990. The axes are generated from the first three principal components of 32 SSR and four AFLP markers. Data were analyzed with the program NTSYS pc 1.7. Source: CIMMYT Applied Biotechnology Laboratory.

View larger version (30K): [in a new window]   Fig. 4. Regression of difference in genetic distance, based on 32 SSR and four AFLP markers, and year of release for 27 CIMMYT spring bread wheat lines released from 1962 to 1990. Source: CIMMYT Applied Biotechnology Laboratory.

View larger version (18K): [in a new window]   Fig. 5. Grain yield (6-yr mean) of eight wheat cultivars as a function of year of release. Cultivars were grown under irrigation and optimal management, including disease and lodging protection, in each of six winter growing seasons (1990–1995) at CIANO (Centro de Investigaciones Agricolas de Noreste) experiment station, Sonora, northwest Mexico. Cultivars were derived from CIMMYT germplasm, and are listed in Table 3. Reprinted with permission from Sayre et al. (1997).

View larger version (32K): [in a new window]   Fig. 6. Mean genetic progress of ten bread wheat cultivars, two tall and eight semidwarfs, produced by CIMMYT and released by the Mexican government from 1950 to 1985. Cultivars were planted over 3 yr at four levels of applied N, 0, 75, 150, or 300 kg N per ha at the CIANO (Centro de Investigaciones Agricolas de Noreste) experiment station in Sonora, northwestern Mexico. Cultivar names are listed in Table 3. Reprinted with permission from Ortiz-Monasterio et al. (1997).

View larger version (32K): [in a new window]   Fig. 7. Relationship between year of release of 15 cultivars and their grain yields under fungicide protected and non-protected conditions for normal planting dates. Cultivars were sown at normal planting dates over four seasons at CIANO (Centro de Investigaciones Agricolas de Noreste) experiment station, Sonora, northwest Mexico. Leaf rust epidemics were established by inoculating spreader rows planted adjacent to plots of cultivars which were not protected by fungicide. Cultivars were derived from CIMMYT germplasm, and their names are listed in Table 3. Adapted with permission from Sayre et al. (1998). g = annual genetic progress.

View larger version (22K): [in a new window]   Fig. 8. Regression of grain yield of 10 historical CIMMYT spring bread wheat lines averaged for 16 hot environments on year of release. Analysis based on data from trials conducted from 1990 through 1992, published in Reynolds et al. (1994). Cultivars were derived from CIMMYT germplasm, and their names are listed in Table 3.

View larger version (15K): [in a new window]   Fig. 9. Regression against time of the mean yield of the top five entries of CIMMYT-derived germplasm expressed as percent of local check for the Elite Spring Wheat Yield Trial (ESWYT 1989–1991) and Semi-Arid Wheat Yield Trial (SAWYT 1992–1997). Between 30 and 50 genotypes were sown in 230 trials conducted between 1989 and 1997. Average yields are less than 2.5 Mg/ha in low-yielding environments and 2.5 to 4.5 Mg/ha in medium-yielding environments. Adapted from Trethowan et al. (2002).