Historical perspectives of cassava breeding in Africa
1982
Beck, B.D.A. (Brian Beck (PVT) Ltd., Zomba (Malawi))
The early records of the introduction of cassava to East and West Africa are reviewed, and the three major cassava-breeding programs that involved the use of interspecific hybridization to obtain resistance to cassava mosaic disease (CMD) are outlined. My earlier work to produce the interspecies hybrid clone 58308 is described: this clone has shown stable resistance to CMD for 22 years under continuous, high-inoculation pressure. Researchers at the International Institute of Tropical Agriculture have shown that this resistance is recessive, is polygenic, and is inherited in a largely additive manner. They have also shown that 58308 provides polygenic resistance to cassava bacterial blight (CBB) and that this resistance is also recessive and is inherited additively. The resistances to CMD and CBB are strongly linked, and this link may occur in the chromosome complement derived from Manihot glaziovii parent Clone 58308 has also been the principal parent in the production of lines with low cyanide in the roots. Resistance to both diseases and the presence of low cyanide have been incorporated into a large number of high-yielding populations at IITA, through a half-sib selection procedure with relatively large families. The future development and the distribution of new disease-resistant, low-cyanide cultivars for the smallholder and for large-scale producers as an industrial feedstock from these populations are discussed
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