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 ...

This paper does not present an exhaustive review of the properties of acid soils. Rather, emphasis is placed on three topics, viz. soil pH, exchange properties, and sulfate sorption, with bias towards the author’s experience with soils from the world humid tropical region. The discussion on pH and exchange properties centers around the selection of laboratory methods, which should give relevant information about field conditions, and about the application of this knowledge to soil management. ...

Information on current progress in the refinement of screening techniques identification of resistant germplasm and breeding lines and assessment of crop losses due to striga attack is presented. A new laboratory-cum-pot steel mesh roll technique which permits interaction of stimulants with soil was developed and found effective in differentiating low from high stimulant-producing sorghum lines. Results correlated well with those from field screening of breeding lines for striga resistance.

Inclusion of trees in cropping systems is an efficient way to recycle nutrients and replenish soil organic matter. In the tropics, P deficiency is commonplace, and rains are erratic in many areas. Mycorrhizal fungi are known to enhance P uptake of the host-plant in low-P soils, and to improve its water relations under drought conditions.

Plant reproduction is a core process in plant breeding. For decades, one can even say for centuries, plant reproductive biology has largely been a matter of observation, description, and philosophical speculation. Only in the last two decades has it entered the experimental phase, and it is in the last decade that tools are emerging that allow manipulation of plant reproduction for the sake of human needs and goals.

Bananas, Musa species, are perennial giant herbs belonging to the family Musaceae (Zingiberales: Scitaminae) (Simmonds, 1966; Tomlinson, 1969). Most bananas are cultivated for their fleshy fruits, but some clones are planted for their edible conns or for fiber. Bananas are among the most important food crops of the tropical and subtropical world. Some 68 million tons of bananas are produced annually, of which only 7 million tons enter the world market (FAO, 1987). This demonstrates that the crop ...

On-farm Adaptive Research (OFAR) In an alftsol area In Southern Benin (Mono Province) started in 1986 with the introduction of a collaborative project of the Direction de la Recherche Agronomique (DRA) of Benin, the Royal Tropical Institute (KIT) Amsterdam, and the International Institute of Tropical Agriculture (IlTA) Nigeria. Major constraints to agricultural development are: • declining soil fertility caused by shorter fallows: • reduction in average farm size because of the Increase in rural ...

I do not propose to say much about the type of verification trial where a single plot using a package of improvements is established on the fields of several farmers. Although they often provide useful information over an area, I consider them to be little more than demonstration plots. Where we have several plots per site, on the other hand, we are forced towards experiments

This volume looks at various aspects of the culturally prescribed roles of women and men - that is, gender issues - in sub-Saharan Africa and their relevance to the recording of facts upon which national policies and plans promoting the welfare of labour and national economic development are supposed to be based. Contributions: Introduction (Christine Oppong) - The demographic profile: sustained high mortality & fertility & migration for employment (Aderanti Adepoju) - Wives & mothers: female ...