Evaluation of cassava clones for yield, acceptability and disease and pest resistance in coastal Kenya.

T.L. Munga

One hundred and fifteen (115) cassava clones were evaluated on-station at two sites during the 2001growing season in coastal Kenya for yield, acceptability and resistance to East African Cassava Mosaic Virus Disease (EACMVD), Cassava Green Mite (CGM) and Cassava Mealybug (CMB). The experimental design was a complete randomised block design with 3 replicates. Plot size measured 2m by 6 m. Cuttings were planted at a spacing of 1 m by 1m. Data on symptom scores and visual incidence of plants affected was recorded at 3 and 6 months after planting (MAP) used as index for resistance. Harvesting was done 11 MAP at Mtwapa and 12 MAP at Msabaha. Data were recorded on number and weight of marketable, unmarketable and total tubers, dry matter (DM) %. At harvesting, farmers assessed the clones using their own criteria. Clones for on-farm testing were selected on yield performance, disease and pest resistance and farmer acceptability. Site, clone, and the interaction between site and clone effects were significant (P<0.01) for total and marketable roots per plot while clone effect was significantly different for marketable yield (kg/plot). Clones performed better at Msabaha than at Mtwapa. The best clones at Msabaha were 2001LML/2095 (197 total roots/plot), 2001LML/939 (98 marketable roots/plot) and 2001LML/1270 (73 total and 61 kg/plot marketable yield/plot). At Mtwapa, the best clones were 2001LML/2095 (213 total roots/plot) 2001LML/1306 (84 marketable roots/plot) and 2001LML/1486 (65 and 59 kg/plot of marketable and total yield, respectively). The highest % incidence for EACMVD, CGM and CMB were recorded at 6 MAPS. The % incidence of EACMVD and CMB were higher in Mtwapa than Msabaha.  Farmers assessed cassava clones based on yield, taste, dry matter content, root size and number and ability of clones to produce a large amount of planting material. Yield, taste and dry matter content influenced farmers to select clones for market or home use.  Farmers selected 78 clones at Msabaha but these were reduced to 37 for further evaluation after rejecting all clones with EACMVD, Cassava Brown Streak Virus Disease, and severe scores of CGM and CMB.