Longitudinal analysis of maize diversity in Yucatan, Mexico: influence of agro-ecological factors on landraces conservation and modern variety introduction

Transformations that farmers bring to their traditional farming systems and their impacts on the conservation and evolution of maize varieties over a 12-year period are investigated using a longitudinal analysis. Despite the increased introduction and supply of improved maize variety seeds in the Yucatan Peninsula, Mexico, over the last 12 years farmers continue to maintain a substantial amount of traditional maize variety diversity. Even with the increased availability of hybrid seeds, farmers in the community of Yaxcaba on average plant more than three quarters of their milpa fields to traditional maize varieties, with the latter one fourth predominately planted to a locally improved variety Nal Xoy, a farm cross of a traditional variety and an improved variety. We observed a significant reduction in yellow – x-Nuuk nal, a long-cycle traditional landrace, paralleled by an increase in short- and intermediate-cycle locally adapted improved maize varieties. We found great differences in the distribution of maize varieties by soil type, with modern varieties being targeted for the rarer, deeper and fine-grained soils, while traditional varieties predominate on the more prevalent stony and thin soils. Our results provide a picture in which most traditional maize varieties in Yaxcaba continue to be maintained by farmers, coexisting with locally adapted improved varieties on the same landscape, and allowing the continued evolution of maize populationsPeer Revie

Manejo de la diversidad de los cultivos en los agroecosistemas tradicionales

Las exigencias en materia de conservación de los recursos fitogenéticos requieren de la contribución de un gran número de actores para la formulación de estrategias apropiadas en función de la variabilidad de climas, eco y agrosistemas, heterogeneidad cultural, factores económicos y genéticos intrínsecos en el material a conservar. Las estrategias generales de conservación in situ y ex situ requieren del desarrollo y mejora de diversas capacidades nacionales y locales que van desde el conocimiento del germoplasma hasta el diseño o mejoramiento de las infraestructuras. El sureste de México forma parte del centro de diversidad mesoamericano donde tuvieron su origen y diversificación el maíz, frijol, Cucurbita, y Capsicum, entre otros, cultivos que además de su importancia socioeconómica regional son fuentes de genes a nivel mundial. Las instituciones locales, regionales, nacionales e internacionales y las comunidades campesinas que usan los recursos fitogenéticos en sus diversas formas y modalidades, ya sea como materia de estudio, alimento (directo o procesado) o como elemento de cambio, tienen la responsabilidad de conservar y hacer uso eficiente del germoplasma. Esta publicación, Manejo de la diversidad de los cultivos en los agroecosistemas tradicionales, reúne una serie de artículos que fueron presentados en la reunión, del mismo nombre, realizada del 13 al 16 de febrero de 2002 en Mérida, México cuyo objetivo fue compartir las experiencias y lecciones aprendidas acerca del manejo de la diversidad cultivada en los sistemas tradicionales, las decisiones de los agricultores, la genética de la conservación y el mejoramiento, y los aspectos sociales, económicos y culturales de las comunidades rurales donde se realiza la conservación en finca

Seed systems and crop genetic diversity in agroecosystems

Poster presented at the First Diversitas Open Science Conference. Oaxaca (Mexico), 9-12 Nov 200

Longitudinal analysis of maize diversity in Yucatan, Mexico: influence of agro-ecological factors on landraces conservation and modern variety introduction

Transformations that farmers bring to their traditional farming systems and their impacts on the conservation and evolution of maize varieties over a 12-year period are investigated using a longitudinal analysis. Despite the increased introduction and supply of improved maize variety seeds in the Yucatan Peninsula, Mexico, over the last 12 years farmers continue to maintain a substantial amount of traditional maize variety diversity. Even with the increased availability of hybrid seeds, farmers in the community of Yaxcaba on average plant more than three quarters of their milpa fields to traditional maize varieties, with the latter one fourth predominately planted to a locally improved variety Nal Xoy, a farm cross of a traditional variety and an improved variety. We observed a significant reduction in yellow – x-Nuuk nal, a long-cycle traditional landrace, paralleled by an increase in short- and intermediate-cycle locally adapted improved maize varieties. We found great differences in the distribution of maize varieties by soil type, with modern varieties being targeted for the rarer, deeper and fine-grained soils, while traditional varieties predominate on the more prevalent stony and thin soils. Our results provide a picture in which most traditional maize varieties in Yaxcaba continue to be maintained by farmers, coexisting with locally adapted improved varieties on the same landscape, and allowing the continued evolution of maize population

Farm, community, and landscape: genetic diversity and selection pressures at different social, spatial, and temporal scales

Peer Revie