Cassava (Manihot esculenta Cranzt) deteriorates rapidly. Hence it is processed into various products within 2 to 3 days after harvesting. For this work, tapioca was produced from three different varieties of cassava. They are Odongbo, Okoiyawo and TMS30572. The sorption isotherm for the tapioca grits from three different varieties of cassava at temperatures 25, 32 and 45°C were determined experimentally and modelled using five different models. Using analysis of variance at 0.01 level, it was shown that the experimental sorption isotherms of the tapioca from the various cassava varieties are not significantly different from each other. However, the Guggenheim (1966), Anderson (1946) & de Boer (1953 (GAB) model gave the best fit for sorption isotherm of tapioca from either the Odongbo or Okoiyawo varieties, while the exponential model was the best for that from TMS30572 variety.

Hermetic cold storage without previous drying (wet-cold storage) was experimented for the preservation of yam pollen grains. Pollens collected from white yam D. rotundata and a wild relative, D. praehensilis, were stored at k80, k20, 5, and 15 mC in sealed packs for 2 years. Pollen samples were drawn for in vitro germination tests after 100 and 700 days, and hand pollination was conducted after 365 and 730 days in storage. Pollen germination responses were not significantly different among the two species. Though pollen maintained germination capacity at all the storage temperature regimes, there was a significant loss in the viability of pollen stored at 5 and 15 mC after 100 days of storage. After 700 days in storage, pollens stored at 5 and 15 mC had lost germination capacity while there were no significant differences in the germination of fresh pollen and pollen frozen at k80 and k20 mC. Hand pollination with pollen of D. rotundata frozen at k80 mC for 365 days gave 69n5% fruit set and 50 % fruit set after 730 days in storage. From these results, the wet-freeze procedure appears promising to execute the establishment of pollen gene banks for yam breeding and for conservation of haploid gene pool of yams in base collections. A pollen storage protocol based on the procedure is recommended.

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To characterise the local seed system and assess the potentials of the vegetable seed sector, a seed survey was conducted in five villages within three states of South Western Nigeria. Using structured questionnaires, 94 farmers from five farm settlement locations covering Ogun, Osun and Oyo states of Nigeria were randomly queried on types of varieties that they propagate, their seed sources, and factors that determined their seed choices. The data collected were subjected to descriptive analysis of simple proportions and percentages. At all the locations, the use of seeds of improved varieties for production of vegetable crops in terms of hectares cultivated was predominant over that of local varieties -100% use of seeds of improved varieties in many cases. About 60% of vegetable farmers sourced seeds from their previously saved harvests, while about 30% purchased seeds from dealers over the 3 years covered by the survey. About 33% of vegetable farmers would select seeds of varieties to cultivate based on high potential crop yield and 32% based on consumer preferences, while 25% of farmers would select seeds of a variety if only it is readily available. The results showed that farmers' demand for the seeds of improved varieties could be elicited with availability of varieties that meet production challenges (high yields) and market needs (consumer preferences). The implications of the results with respect to prospects for commercial vegetable breeding and seed production were discussed. But indications are that the seed system can be improved when crop breeders and seed producers regularly evaluate the dynamics of consumer quality preferences and continuously generate varieties that satisfy them.