Abstract

Parkes E.Y.,D. F. K. Allotey, E. lotsu, and E. A. Akuffo

Introduction of improved cassava varieties may require proper fertilizer management for increased and sustained root production. A factorial experiment involving five cassava genotypes and four levels of fertilizer with three replications was established at the Council for Scientific and Industrial Research (CSIR)-Crop Research Institute, Fumesua near Ejisu, Ghana (60 43’00’N and 10 28’0”W). The five cassava genotypes (Debor, Afisafi, Tuaka, Afebankye and Sisipi 290) were fertilized with NPK at the following rates:- F0: 0 N – 0 P2O5 – 0 K2O kg/ha (Control), F1: 60N – 30 P2O5 – 90 K2O kg/ha (Low), F2: 120N – 60 P2O5 – 180 K2O kg/ha (Medium) and F3: 180N – 90 P2O5 – 270 K2O kg/ha (High). The two trials were conducted from 9th September 2007 to 17th September 2008 and 22nd May 2009 to 22nd July 2010. Fertilizer significantly (P < 0.05) increased tuber yields. Fresh tuber yields of all the genotypes except Afisafi and Sisipe 290, generally, increased with increasing rates of fertilizer application. Whereas fresh root yields of Debor increased with increasing rates of the fertilizer up to the maximum rate (F3), yield reductions of Tuaka, Afisafi and Sisipe also occurred at this rate. All the genotypes gave similar root yield except Sisipe 290 which produced significantly lower root yield. Interaction between genotypes and fertilizer was significant. Fresh root yields of Debor, Tuaka and Afebankye were significantly (P < 5%) higher over the control at the lowest rate (F1). The economic rate of fertilization for higher fresh root yield of all other genotypes except Debor is F1. Sisipe 290 had the highest starch content at the F1 fertilizer treatment. For higher fresh root yields, 60N – 30 P2O5 – 90 K2O kg/ha (F1), 120N – 60 P2O5 – 180 K2O kg/ha (F2) and 180N – 90 P2O5 – 270 K2O kg/ha (F3) are recommended for Afebankye and Tuaka, Afisafi and Debor respectively. With regards to starch content, 60N – 30 P2O5 – 90 K2O kg/ha (F1 ) rate is recommended for Debor, Afisafi and Sisipe 290, while F2: 120N – 60 P2O5 – 180 K2O kg/ha for Tuaka.