Seeds of twenty-two cowpea (Vigna unguiculata (L.) Walp) lines/cultivars were inoculated with Aspergillus parasiticus (Link) (NRRL 3145) and aflatoxin production was evaluated. All the cowpea samples were susceptible to Aspergillus infection and subsequent aflatoxin production. The amount of aflatoxin produced ranged between 466.6 micrograms/kg to 1 806 micrograms/kg in the case of B (B1 + B2) and 20.8 micrograms/kg to 82.7 micrograms/kg of seed in the case of G (G1 + G2). On the basis of the amount of aflatoxin produced on different samples, it is evident that there is at least partial resistance to aflatoxin production in the tested cowpea lines/cultivars. On the basis of the results obtained in this investigation it is apparent that further selection and breeding could provide cowpea cultivars which are resistant to A. parasiticus infection and aflatoxin production.

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The resources for agricultural and natural resources research have declined in Zambia. Therefore, there is a need to generate evidence on the rate of return (ROR) on past investments in sorghum research. Zambia's sorghum research programme has released seven widely adapted varieties and management practices. The objective of this study is to assess the socio-economic impact of sorghum research in Zambia from 1983 to 2010 and to assist in identifying priority areas for future research. A multistage sampling procedure was used in the study and a total of 278 farmers comprising 241 small-scale, 25 medium-scale and 12 commercial farmers was interviewed. A surplus approach was used to estimate the ROR to research and development investment. The Akino-Hayami and simple benefit-cost analysis techniques were used to estimate the ROR to investment. The estimated adoption rate in the sorghum producing sector in Zambia was 33.5%. Farmers identified early maturity, drought tolerance and high yield as the most important attributes of improved varieties. About half of the respondents cited a lack of improved seed and information as reasons for non-adoption. The estimated ROR for investment in sorghum research and complementary services ranged from 12% to 19%, depending on the future adoption path.

Kenya has been transformed into a net importer of maize, which is its major staple. As maize accounts for a major portion of calorific and protein intake for more than 90% of Kenyans, the fact that Kenya must increase farm productivity and income is no longer debatable. Past successes in maize production in Kenya were achieved by exploiting a synergy between technology development, dissemination, and seed multiplication and distribution programmes. However, lack of funding, poor linkages between research and farmers, lack of private investments in maize research, and human capital turnover are problems that need serious attention. Two stage linear regression analysis is used to calculate the rate of return to investment in Kenyan maize research for the 1955-1988 period. The result indicated that improvement in maize yield and expansion of maize area are explained by, inter alia, increase in research and extension expenditures and the spread of hybrid seed; yield is also positively influenced by use of fertilizer while greater area expansion is stimulated by higher maize producer prices. The results also indicate that maize research, extension and seed programmes contributed to attainment of higher maize yields, expansion of maize area and to growth in output.

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