Farmer’s Knowledge on Selection and Conservation of Cassava (Manihot esculenta) Genetic Resources in Tanzania.

Farmers have traditionally depended on their knowledge to cultivate diverse set of crop population for their subsistence. This practice has contributed to high genetic diversity found in farmers’ fields. Occurrence of natural disasters has threaten survival of crop populations and diversity, and thus causing food shortage. Breeding efforts have been targeted to develop crop varieties which can tolerate these natural disasters but there has been poor adoption by farmers. There is a need to understand social and biological factors which farmer base on during selection and maintenance of their genetic resources. There is limited information for researcher’s understanding of factors that farmers considered for landraces selection and conservation. In a view of the above mentioned problems a study was conducted using PRA tools to gather information on conservation of cassava genetic resources. The study found that farmer’s decision on what landrace to plant was what has shaped the diversity. Farmer’s decision comprised of diverse factors from food security, market forces and culinary attributes. The study found that seed (stem cuttings) flow occurs as farmers exchange or buy from local market. These exchanges occur within and outside the village. Most of cassava landraces were indigenous to the place and have been grown for more than 40 years, and only 8.4% were newly introduced. There was considerably loss of landraces due to disease, pest and drought outbreaks. Landrace selection decision was made by both men and women and these decisions on the other hand influenced the diversity of cassava landraces found in farmer’s field. Cultivars like Kiroba, Kibandameno and Msenene were found in every farmer’s field in those particular areas but other cassava landraces differed considerably from one field to another. It is concluded that farmer’s knowledge is useful in conservation of cassava genetic resources for improved livelihood. Therefore farmer’s knowledge should be incorporated in research intervention packages to be able to address specific needs of farmers in a particular area and fasten the adoption process. Keyword: Farmer’s knowledge; Genetic resources; Kiroba, Farmer’s decision making

Effect of genotype and genotype by environment interaction on total cyanide content, fresh root, and starch yield in farmer-preferred cassava landraces in Tanzania

High starch yield is the most important trait for commercialized cassava starch production. Furthermore, cyanide present in cassava roots poses a health challenge in the use of cassava for food. Cassava genotypes have varying maturity periods that are also environmental dependent. This study aimed at identifying suitable cultivars and optimum time of harvest to maximize starch production across three environments. The study found significant difference between genotypes, locations, harvest period, and all the interactions (P ≤ 0.001) for all traits analyzed. Kiroba recorded high starch yields of 17.4, 12.7, and 8.2 t ha−1 at Chambezi, Amani, and Magadu, respectively. Kilusungu recorded highest cyanide content of 300–400 ppm across all locations but Kiroba recorded highest values of 800 ppm, 15 months after planting at Chambezi. Genotype by environment (GGE) biplot analysis revealed that Kiroba was a superior cultivar in terms of starch yield. Kilusungu recorded highest cyanide content and average starch yield, therefore suitable for use in starch production. The study confirmed effect of genotype and genotype by environment interaction, Kiroba cultivar was superior in terms of starch yield and maximum starch yield was obtained at 9 months after planting. Nyamkagile and Kibandameno had the lowest cyanide content across all environments