Cassava germplasm strategies for Africa

Se indican brevemente los tipos de germoplasma requeridos para las diferentes zonas agroecologicas donde se cultiva la yuca en terminos de lo que ofrece el principal proveedor (America del Sur). Se examinan la franja de la costa atlantica, los bosques humedos tropicales, las sabanas extensas y las zonas aridas de Africa en relacion con zonas similares de America del Sur, con enfasis especial en Brasil, que puede satisfacer la mayoria de las necesidades de Africa debido a la diversidad de sus ambientes edafoclimaticos. Tambien se discute la erosion genetica; sin embargo, no hay evidencia tangible de que la yuca este sufriendo severa erosion genetica en sus centros de origen (neotropico americano). Se enumeran las principales colecciones de germoplasma para las Americas, Africa y Asia. Tambien se revisan los recursos geneticos de especies silvestres de Manihot. Las estrategias futuras deben considerar latitudes mas templadas mas al sur, salinidad, humedad atmosferica y biologia reproductiva. Se debe dar alta prioridad a la recoleccion de germoplasma para transferencia a regiones africanas, a saber: cv. costeras, cv. riberenas, cv. con pulpa amarilla, cv. tolerantes a la sequia y poblaciones silvestres de yuca en el neotropico. (CIAT) spa

The types of germplasm needed for the different agroecological zones where cassava is grown are outlined briefly in terms of what the main supplier (South America) has to offer. Africa's Atlantic coastal belt, its tropical rain forests, its extensive savannas, and the arid zones are examined in relation to similar zones in South America, with particular emphasis on Brazil, which alone can meet most African needs thanks to the diversity of its edaphoclimatic environments. The topic of genetic erosion is also addressed; there is no tangible evidence, however, that cassava is undergoing serious genetic erosion in its centers of origin (American neotropics). Major cassava germplasm collections are listed for the Americas, Africa, and Asia. Genetic resources of wild Manihot species are also reviewed. Future strategies should consider more temperate latitudes farther south, salinity, atmospheric humidity, and reproductive biology. High priority should be given to collecting germplasm for transfer to African regions, as follows: coastal cv., riverine cv., cv. with yellow flesh, drought-tolerant cv., and wild populations of cassava in the neotropics. (CIAT) eng