Abstract

A study was conducted at Kyambogo University Farm in randomized complete block design with three replications to assess the effect of NPK (17:17:17) fertilizer on the growth and tuber yields of two newly developed cassava (Manihot esculenta Crantz) varieties, NAROCASS 1 and NASE 14. Cassava varieties were assigned to the main plots, while fertilizer rates (zero/control, 200, 400, 600 kg/ha) were sub-plots. Fertilizer was applied in two splits, at planting and four months after planting. Fertilizer application significantly (P<0.05) increased the cassava stem heights to first branching and at harvest, and the number of stems per plant when compared with the control treatments. Mean stem heights to first branching and at harvest of plants that received NPK were higher than those of the respective control treatments by 62.8 and 70.5% for NAROCASS 1, and 57.0 and 76.5% for NASE 14, respectively. Fertilizer rate of 400 kg/ha significantly increased the lengths, numbers of tubers and tuber yields per plant when compared with the control treatments. Mean lengths, numbers of tubers and tuber yields of plants that received NPK were higher than those of respective control treatments by 48.2, 36.9 and 68.3% for NAROCASS 1, and 39.9, 50.5 and 67.6% for NASE 14, respectively. Therefore, to achieve optimum tuber yields of newly developed cassava varieties, farmers should integrate NPK fertilizer application into already existing management practices, particularly the use of high quality planting materials and integrated pest, disease and weed management. However, government ministries concerned should ensure that inorganic fertilizers are readily accessible and affordable to farmers.

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