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Diaz, J.

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Diaz, J.

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    Annual research report 2000: Maize genetic resources
    (CIMMYT, 2000) Taba, S.; Remier, H.; Kirubi, D.; Diaz, J.
    Maize genetic resources program has three pillars, namely germplasm accessions management, in-situ biodiversity conservation, and prebreeding. Germplasm accessions management includes specific cooperative project ofregeneration of the Latin American maize landrace accessions, and evaluation and curatorial of the CIMMYT bank accessions. In-situ-biodiversity conservation entails the collecting and evaluation, and enhancement of specific landraces that are grown by the farmers in the context with their growing environment and cultural heritage in Mexico. Prebreeding is to develop and improve CIMMYT gene pools with incorporation of appropriate germplasm sources that are adapted in tropical, subtropical, and highland environment. For in-situ biodiversity conservation we evaluated new collections of Mexican race Zapalote Chico with our Mexican collaborators. Evaluations of additional Tuxpefio race and Brazilian races of Cateto and its subraces were conducted for development of core subsets. Formation and evaluation of breeding crosses of elite accessions were initiated or advanced in GEM type germplasm enhancement. In prebreeding topcross evaluations of a few tropical early pools, progeny formation of S 1 or S2, and development of donor sources were made mostly for yellow gene pools. Bank management and accessions introduction through the collaborative project with Latin American countries resulted in the total number of accessions that amounted to 20,863 as of September 2000. We made the seed shipment from Bank in the seed packets of 5,248 during the year.
    Publication
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    Evaluation of Zapalote Chico accessions for conservation and enhancement
    (Consiglio per la Ricerca e la sperimentazione in Agricoltura, Unità di Ricerca per la Maiscoltura, 2006) Taba, S.; Diaz, J.; Aragon Cuevas, F.; Rincón-Sánchez, F.; Hernandez, J.M.; Krakowsky, M.
    Conserving traditional maize (Zea mays L.) landraces grown by farmers in Latin America can con- tribute to food security. Core subsets of such landraces that represents that diversity can be used for their en- hancement. One such enhancement effort was conducted on a total of 81 accessions drawn from the CIMMYT maize collection of the race Zapalote Chico and newer accessions collected in 1999 from Istmo de Tehuantepec, Oaxaca, Mexico, where the race Zapalote Chico is pre- dominantly grown. These accessions were evaluated at four locations in the Mexican states of Morelos, Guerrero, and Oaxaca for agronomic and morphological traits to as- sess the intraracial diversity for conservation and en- hancement. Eleven agronomic and morphological traits were measured and used for a multivariate cluster analy- sis. The cluster analysis produced four non-overlapping clusters with 63 accessions, indicating the intraracial di- versity of the Zapalote Chico. The analysis also formed two other clusters with four races, including Tepecintle and Olotillo, which have been introduced to the region of Istmo de Tehuantepec. Using a selection index that ac- counts for grain yield, grain quality, and standability, and an agronomic performance rating, a breeder core subset (the best 20%) was chosen to represent phenotypic diver- sity among the clusters. In the core subset, fifteen acces- sions comprise the core subset of the race Zapalote Chico and three accessions comprise the core subset for the other races. These core subset accessions, which repre- sent the diversity of the regional landraces of maize, can be enhanced through introgression of improved lines or populations for yield potential, drought resistance, and ear rot resistance, while maintaining the desirable grain quality traits of the original races.
    Publication
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    Identifying appropriate germplasm for participatory breeding: an example from the central Valleys of Oaxaca, Mexico
    (CIMMYT, 2000) Bellon, M.; Smale, M.; Aguirre Gomez, J.A.; Taba, S.; Aragon Cuevas, F.; Diaz, J.; Castro, H.
    Identifying the appropriate germplasm to be improved is a key component of any participatory breeding effort because of its implications for impacts on social welfare and genetic diversity. This paper describes a method developed to select a subset of 17 populations for a participatory breeding project from a set of 152 maize landraces. The larger set of landraces was collected in order to characterize, for conservation purposes, the maize diversity present in the Central Valleys of Oaxaca, Mexico. The method combines data representing the perspectives of both men and women members of farm households and those of genetic resources specialists, including professional plant breeders, gene bank managers, and social scientists. The different perspectives complement each other. The results show that when the choice of germplasm is based only on the perspective of genetic resources specialists, traits and materials that are important to farm households may be ignored. Such selections may be less valuable to farmers, limiting the impact of the participatory breeding effort on their livelihoods. However, the findings also indicate that relying solely on the perspectives of farm households may lead to lower diversity. Choosing populations based solely on either perspective involves a social cost-either in terms of diversity or in terms of farmer welfare. Although our approach has limitations, many of which are common to participatory research, it represents a systematic method for meeting one of the important challenges of participatory plant breeding.
    Publication