Cassava breeding through complementary conventional and participatory approaches in western Kenya.
Year: 2011
Type: dissertation
Abstract: Participation of farmers in plant breeding programmes has been reported to increase \nbreeding efficiency. Farmers’ participation bridges the gap between variety development and \ndissemination and provides an opportunity for farmers to select varieties they prefer. The \nbreeders on the others hand learn more about the farmers’ preferences and the environment \nin which the new varieties will be grown. However, the advantages of participatory breeding \ncan best be realized when farmers’ indigenous technical knowledge (ITK) and experience \ncomplement the breeder’s scientific knowledge and skills. Cassava (Manihot esculenta \nCrantz) is a clonally propagated crop grown in diverse environments by small scale farmers \nfor subsistence. Information on the roles of farmers and breeders at various stages of \nbreeding and their ability to effectively participate in breeding programmes is limited. The \nobjectives of this study were to determine: (1) cassava farmers’ preferences, production \nconstraints and systems; (2) farmers’ selection criteria of cassava varieties; (3) genetic \ninheritance of farmer preferred traits; (4) how farmers and breeders complement each other \nat all stages and activities of cassava breeding. \nParticipatory rural appraisal was conducted in three purposefully sampled districts of western \nKenya based on ethnicity and agro-ecology. The results reveal that cassava is \npredominantly grown by small scale farmers with mean land size of 1.6 ha mainly under \nmixed cropping system for subsistence. The storage roots are eaten either after boiling or \nprocessing to flour. The majority of farmers (over 60%) are aware of the improved varieties \nbut adoption rate is low (18% in some districts). The effects of pests and diseases, and the \nlack of high yielding varieties, capital, land, and disease free planting material are the most \nimportant constraints to cassava production. Farmers prefer tall, high yielding varieties that \nare resistant to diseases and pests, early maturing and long underground storability of \nharvestable storage roots. The districts surveyed significantly differed in popularity of \nutilization methods, traits preferences and relative ranking of the production constraints \nindicative of differences in ethnicity and agro-ecology. \nThree farmer groups from the three districts selected in western Kenya were used to study \nfarmers’ variety selection criteria based on their own indigenous technical knowledge (ITK). \nThe groups evaluated 15 (10 landraces and five improved) popular cassava varieties with \nconcealed identities on their farms. The results revealed that farmers have effective methods \nof selecting varieties for most of their preferred traits. However, ITK alone cannot be used to \nevaluate all the important traits, such as cyanide content. \n \nThe genetic inheritance of farmer preferred traits was determined through a genetic study. \nSix landraces and four improved varieties popular in western Kenya were crossed using the \nNorth Carolina mating design II to generate 24 full-sib families. The 24 families, represented \nby 40 siblings each, were evaluated at two sites, Kakamega and Alupe research station \nfarms, in a 24 x 40 a-lattice design. General combining ability (GCA) and specific combining \nability (SCA) mean squares were significant (P<0.05) for all traits evaluated except dry \nmatter content and cyanide content. However, non-additive gene action predominated over \nadditive gene for cassava mosaic disease (CMD) resistance, height to first branching, total \nnumber of storage roots per plant and fresh storage root yield in all environments. The best \ncrosses were not necessarily obtained from parents with high general combining ability \nconfirming the presence of non-additive gene action. The best performing parents per se did \nnot necessarily have high GCA effects implying that selection based on the per se \nperformance of parents may not always lead to development of superior hybrids. \nThe clonal evaluation trial (CET) was established at Alupe research station and evaluated by \nthe breeder and farmers from two districts independently. Three selection criteria were \ntested to determine the most appropriate approach to selection of varieties that meet both \nfarmers’ and breeder’s preferences. The selection criteria were; farmers’ independent \nselection index (SI) derived from farmers’ selection criteria from each district, breeder’s \nnegative selection and independent SI, and a participatory SI which combines farmers’ and \nbreeder’s selection criteria. There was 14% overlap among the top 100 varieties selected by \nfarmers from all districts and the breeder when independent SI were used. However, there \nwas 49% overlap among the top 100 varieties selected by farmers using participatory SI and \nthe breeder’s SI. The farmers and the breeder have a role to play in the variety development \nprocess. Varieties with traits preferred by both the farmers and the breeder are likely to \nenhance breeding efficiency and effectiveness.
Author: Woyengo Vincent. Were
Language: English
Topic: Cassava research and cyanide
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
Funder: Inyuvesi Yakwazulu-Natali
OpenAlex ID: W1557430781