Ecological diversity and rice varietal improvement in West Africa.

Abstract

This chapter describes the impact of regional rice research activities on varietal improvement in 7 of the most important producers of rice in West Africa: Côte dacute˜ Ivoire, Ghana, Guinea, Mali, Nigeria, Senegal and Sierra Leone.

Crop improvement, adoption, and impact of improved varieties in food crops in sub-Saharan Africa

“…Productivity gains are more likely to be related to the effect of cleaner seed than of genetic change. Additionally, variety-specific comparisons show that productivity gains from released in-country landraces are substantially lighter than heavier yield differences estimated for more modern materials characterized by greater breeding content (Dalton and Guei, 2003).…”

“…For example, estimated that improved varieties from the Rokupr Research Station had reached 56% of rice-cultivated area in Sierra Leone in 1990. With somewhat different emphases, three other studies arrived at an estimated annual rate of return of between 18% and 34% to rice improvement research in Sierra Leone (Dalton and Guei, 2003 Almost all the adoption and impact assessment research addressed improved cultivars in Oryza sativa, which was first introduced into West Africa more than five centuries ago by Portuguese explorers returning from India. Locally adapted varieties of Asian rice evolved from these initial and subsequent introductions mediated by centuries of farmer selection.…”

“…The NERICA varieties were too early in the breeding pipeline and in the adoption process to be considered in the 1998 Initiative (Dalton and Guei, 2003). Ten years later, AfricaRice was heavily involved in documenting the spread of the NERICA varieties throughout SSA.…”

“…Genetic improvement of rice in Africa is characterized by a rich if somewhat disjointed research history (Dalton and Guei, 2003). Two rice species (Oryza sativa from Asia and O. glaberrima domesticated in Africa), five rice growing environments (uplands, rainfed lowlands, irrigated lowlands, mangrove swamps and deep-water regions), several bilateral organizations (especially Institut de Recherches Agronomiques Tropicales (IRAT) and Centre de Coopération Internationale en Recherche Agronomique pour le Dévelop-pement (CIRAD)), and three CG Centers (AfricaRice, the International Rice Research Institute (IRRI) and the International Institute of Tropical Agriculture (IITA)) figure prominently in that history, which has been shaped by investments in national programmes since the early 1950s in Nigeria and in the Rokupr Research Station in Sierra Leone for regional mangrove rice improvement since the mid-1930s.…”

“…In rice, using a cut-off date of 1960 or 1965 would bring several popular introduced purified landraces into play. Inclusion of these materials in the set of modern cultivars would result in a sharp rise in the adoption level in some large rice-growing agroecologies in West Africa (Dalton and Guei, 2003). They were listed but not included as improved varieties in the 1998 Initiative; therefore, we opted for the same course of action to promote consistency in comparing estimates over time.…”