CBN-V Video Archives - S6-07
Utilization of Genetic Resources for the Improvement of Cassava in Sub-Saharan Africa (SSA

Dixon A.G.O.¹, R. Asiedu¹, J.B.A. Whyte² and N.M. Mahungu³

1. International Institute of Tropical Agriculture (IITA), P. M. B. 5320, Ibadan, Nigeria A.DIXON@CGIAR.ORG
2. East Africa Root Crops Research Network and IITA-Eastern and Southern Africa Regional Center, Kampala, Uganda,
3. Southern Africa Root Crops Research Network, Lilongwe, Malawi

        Cassava improvement strategies are discussed in relation to target ecologies, varietal needs, genetic variability and relationships, as well as utilization of African and exotic germplasm. Significant advances have been made in broadening the genetic base of cassava and diversifying resistance to the major biotic and abiotic stresses in SSA. This has been through a combination of conventional and new approaches, including systematic introgression of Latin American germplasm with African landraces, interspecific hybridization, ploidy manipulation, in vitro culture, molecular techniques, field testing and selection. Additional variability of the previously untapped African landraces has proven useful for improving breeding populations for desirable traits especially for resistance to the cassava mosaic disease and green mite, as well as the preferred food quality and canopy characteristics. Several improved genotypes and their seed populations have been developed for a range of ecologies including wet inland valleys, moist and dry savannas and the mid-altitudes. These incorporate multiple pest and disease resistance and the desired traits of early vigor in plant growth for high foliage yield, appropriate plant architecture, and early bulking of storage roots, with high dry matter content, low cyanide, high carotene, ease of peeling, acceptable root shape and food quality. The characteristics of the improved germplasm are useful in SSA as a major source of income from industrial use and in the animal feed sector as well as in many non-traditional food uses. The improved germplasm are shared within the region as in vitro, virus-tested and certified plantlets and seed populations for evaluation. Between 1994 and 2000, over 350 improved genotypes and over two million botanic seeds of different families of superior cassava parents were distributed to NARS in SSA. This has led to the widespread and successful deployment of varieties with multiple disease and pest resistance and suited to various end-uses and farming systems in SSA.

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