Cassava Research Progress Report 1985-1986

Trabajo presentado en el Root and Tuber Crops Co-ordinating Committee, 27 October 1986

Results of cassava trials harvested in the 1985/86 season by the Root and Tuber Crop Research Programme in Ukiriguru, Tanzania, are reported. In the preliminary yield trial, 46 var. were selected for root yields higher than those of control var. Liongo-C (5.4 kg/plot). In the intermediate yield trial, 24 out of 40 var. were selected for root yields ranging between 7.7-13.8 t/ha, and 20 for high shoot yields (9.0-17.4 t/ha). Yields of 18 var. included in the advanced yield trial are also given. In the uniform yield trial conducted at 4 ecologically distinct sites (Ukiriguru, Naliendele, Tumbi, and Chambezi), 12 var. were evaluated for root yields, reaction to CAMD and Mononychellus tanajoa, plant establishment, and DM (percentage). The performance of cassava (C) var. Liongo and Aipin Valenca was evaluated for the 2nd time in an intercropping trial with cereals (maize (M) and/or sorghum (S)), cowpeas (CP), and sweet potato (SP) in single-, 2-, or 3 crop combinations using different cropping patterns. Gross returns and LER (1.49-2.42) were higher for selected intercropping systems including C + SP, C + S + SP, C + CP + SP, C + M + SP, C + M + S + SP (the latter 2 selected in 1983/84), C + CP + S + SP, C + S + M, and C + CP + M + S, which will be further evaluated. The effect of harvesting leaves (0, 1-, 2-, 3-, and 4-mo. intervals) on shoot and root yields was evaluated using cassava var. Liongo and Aipin Valenca. The former var. yielded more leaves than the latter and the 1-mo. plucking interval gave the highest leaf yields but also reduced root yields by 45.2 percent. Preliminary results of a fertilization trial conducted in Nyanghomango showed no significant response of cassava root yields to NPK (20-10-10 kg/ha, resp.). (CIAT) eng