Manual for Collection of Cassava Germplasm and Associated Farmer Knowledge in Eastern and Southern Africa

Abstract

Cassava germplasm and associated farmer knowledge from southern, eastern and central Africa is under represented in national and international germplasm collections. This germplasm consists mainly of farmer varieties (landraces) which have been grown for many years and harbor valuable adaptive gene complexes that have evolved under human and environmental selection pressures. The current situation of lack of a repository means that (1) local landraces are not readily available to breeders (2) some farmer landraces contain genetic variation and are not ‘clonal’ as researchers and breeders assume, and no ‘type specimen’ exists so breeders are often not sure of what they are breeding with, (3) disease-free farmer landraces are not available, preventing the movement and sharing of germplasm, (4) landraces and the adaptive gene complexes they harbor are vulnerable to genetic erosion from the spread of improved varieties with increased breeding activities in the region and in the face of devastating diseases such as cassava brown streak disease which may cause the total loss of susceptible landraces, and (5) there is no germplasm database concerning the various attributes of particular clones, geographical location and farmer perceptions for use as a decision-making tool. This lack of ‘farmer-centric’ information means that breeders may not fully understand the subtleties of farmer preferences with implications for varietal adoption of improved germplasm