Variety use and development, seed production and storage by farmers under local conditions, and seed exchange mechanisms are presented as the three principal components of a dynamic system that forms the most important seed source of food crops for small farmers in developing countries . The information on this topic is based on a literature review and a case study . Analysis of strengths and weaknesses of local seed systems leads to the conclusion that local seed systems and the formal system are complementary . Integrated approaches in breeding, and seed production and distribution show to have promising potential for improving seed supply for small farmers .

The assumption that the importance of cassava in expanding food production in developing countries is increasing is questioned. Data for a 22-year period indicated that the only tuber crop gaining in importance on a world scale was potatoes. Cassava production had lagged behind population growth in Africa and the relative increase in production was lower than that of maize. (Abstract retrieved from CAB Abstracts by CABI’s permission)

The DM production of a number of cassava cultivars was simulated with a modified version of the SUCROS model. The overall behaviour of the model was validated with data from periodic harvests. The costs of maintenance respiration of stems and leaves were adjusted by curve fitting using data from one of the experiments. Agreement between experimental and model results was generally good. The model describes basic physiological processes and can be used to simulate growth of different cultivars in various climates. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Yields of cassava roots were greatly increased by grafting or budding Manihot glaziovii on to cassava stocks. The system, developed in 1952 by a Javanese farmer named Mukibat, is described and illustrated. Yields, at about 96 t/ha year, are about double those from conventional cassava. The cuttings can be replanted after harvest, and the Satrawi modification, in which 1 M. glaziovii scion is grafted on to 3 cassava rootstocks, is reported to yield well in shade where conventional cassava will not grow. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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