YIELD AND NUTRITIONAL QUALITIES OF CASSAVA (Manihot esculenta Crantz) AS AFFECTED BY FERTILIZERS AND LENGTH OF STEM CUTTINGS

Abstract

The effects of manure types and length of stem cuttings on the growth, yield and quality of cassava were investigated in a research conducted between June, 2011 and March, 2012 at the Teaching and Research Farm, the Federal University of Technology Akure (Latitude 70 18’N and Longitude 50 7’E). The experimental design was a split plot with the different manure types as the main plots while the varied cassava cuttings formed the sub plots. The five fertilizer treatments were 450kg ha-1 NPK 12:12:18, 2tha-1 compost, 2t ha-1organomineral fertilizer, 4t ha-1 wood ash and the control (no fertilizer) while the sub plots consisted of 10, 15 and 20 cm cassava cuttings respectively. The Furadan Treated cassava cuttings (TMS 98/0581) were planted at 1m by1m in June 2011 and the manure applied in a ring at 10 cm from the plant at 8 weeks after planting. Pre-treatment soil analysis result indicated the soil at the experimental site to be sandy clay loam and of medium acidity of pH 5.8 while the nutrient status showed 0.08% N, 1.49% organic matter, 0.15 cmol/kg Na, 0.17cmol/kg K, 4.0 cmol/kg Ca, 1.20 cmol/kg Mg, and 11.7% P. The percentage increase in plant height in plots treated with 450 kg ha-1 NPK 12:12:18, 2 t ha-1 compost, 2t ha-1organomineral fertilizer, 4t ha-1 wood ash over plot without fertilizer treatment were 9.24%, 18.48%, 20.11%, and 17.39% respectively, while the stem girth were 4.98%, 12.10%, 13.52% and 8.90% respectively. The highest yield of 40.1t ha-1 in plot treated with organomineral over the plot without the manure treatment was 50.2 % while the percentage increase in 450kg ha-1 NPK 12:12:18, 2t ha-1 compost and 4 t ha-1 wood ash over the control were 26.2%, 39% and 33.3% respectively. Cassava cutting lengthsof 15 and 20 cm had 26.1% and 27.1% yield increase over 10 cm cutting respectively. The effects of manure types on the mineral composition of the fresh tuber revealed the highest values of K, Ca and Mg were observed in plot treated with wood ash while the least value were obtained in plot without manure application. The manure treatment did not produce significant differences in carbohydrate contents and fibresthough NPK, compost, organomineral and wood ash respectively produced 0.7%, 1.3%, 2.0%, and 1.4% increase over the plot without manure treatment. The highest value of 1.79% protein was obtained in plot treated with 450kg ha-1 NPK 12:12:18 followed by 2 tha-1organomineral with 1.76%, 2t ha-1compost with 1.62%, 4t ha-1 wood ash with 1.62% and the control as the least with 1.42%. Significantly high HCN was obtained from NPK 12:12:18 and organomineral with 2.75 mg/kg and 2.61 mg/kg while significantly lower value of 2.54 mg/kg were observed under the compost treatment. Lower values of hydrocyanic acid depicting higher cassava quality were observed in plots treated with organic fertilizers compared to the inorganic fertilizers.