The problem has been, for decades, that the world's top scientists have not concentrated on the most important problems of small-scale farmers. If someone is dying of thirst, and you give him fried chicken, you are not going to save him, even if he does also happen to be malnourished. You have to respond to people's most important needs--their limiting factors.
By far the largest problem worldwide with respect to the lack of appropriate agricultural technologies is that the CGIAR system, dominated by plant geneticists, has already decided what small farmers need, without being willing to look at all the indications that their priorities are dead wrong. The limiting factors of the vast majority of smallholder farmers in Africa are NOT genetic. The limiting factors for African smallholders are soil fertility, and more specifically soil nitrogen (and to a lesser extent, phosphorus), and water. But inorganic fertilizer is now priced way beyond smallholders' reach. This fact is recognized by knowledgeable agronomists, and that is why they talk so much about subsidizing inorganic fertilizers. But subsidized fertilizers will only prolong the agony; they will artificially make green manure/cover crops and soil-enriching agroforestry less attractive, thereby putting off the moment when farmers will switch to the only technologies that can truly and sustainably solve the problem of African soil fertility.
Micro-scale water management is the second very important answer to Africa's low productivity, and the CGIAR system has done even less along these lines. I know some small NGOs (with budgets in the hundreds of thousands of dollars) in Central America that have developed more small-scale water management technologies than has the entire CGIAR system.
If you are genuinely interested in the well-being of small-scale farmers, you will look into EPAGRI's work with green manures in Santa Catarina State, Brazil, COSECHA's work with small-scale water management in southern Honduras, FAO's previous work in Lempira Dept., Honduras, green manure/cover crop work in Zambia, small farmers' innovations near Bamenda, Cameroon, and even ICRAF's work in Kenya and Malawi. The answers--the technologies Africa's farmers really need--are already out there in the field. I would be happy, together with people like Jules Pretty and Pedro Sanchez, to develop an itinerary for you to go and study these technologies and their rapid adoption by smallholder farmers.