Abstract
There is paucity of quantitative information on herbicide effectiveness in relation to the yields of cassava cultivars to guide the use of herbicides by farmers. Field experiments were conducted in June, 2013 and June, 2014 cropping seasons at the University of Uyo Teaching and Research Farm, Uyo, to study the effects of selected herbicides on growth, yield and garification qualities of some cassava (Manihot esculenta Crantz) cultivars. A split-split plot arrangement in a randomized complete block design, replicated three times was used. Main treatments were three cassava cultivars; (TMS 97/0162, TMS 01/1412 and local cultivar- Obubit okpo), sub treatments were four types of herbicides; Atrazine, Diuron, Raft and Primextra. The sub-sub treatments were five rates of herbicide application; 0, 1.0, 2.0, 3.0 and 4.0 kg a.i/ha. Data collected on growth, yield and garification qualities were subjected to analysis of variance. Results showed that cassava height (cm), number of tubers/plant, tuber length, tuber circumference (cm), weight of tuber (kg) and tuber yield (t/ha) decreased as rate of herbicide application increased. TMS 01/ 1412 had the highest yield of 26.81t/ha and 27.46t/ha in 2013 and 2014 respectively. Garification qualities were also significantly (p< 0.05) affected in both cropping seasons. Garification qualities varied among cultivars, local cultivar ranked highest for sipping, TMS 97/0162 highest for texture and TMS 01/ 1412 highest for moulding. The herbicide Raft gave the highest yields of 26.31t/ha and 27.64t/ha respectively for years 2013 and 2014. Based on these findings, TMS 01/1412 and Raft at 2.0 kg a.i/ha is recommended for increased cassava production.