Optimization of the Size Distribution of Potato (Solanum-tuberosum) Tuber Using a Second-Order Rotatable Design
Mr. Julius K. Koech, Prof. John M. Mutiso & Prof. Joseph K. Koske

Abstract
Marketability of potato tubers due to its size has continued to remain big challenge among-smallholder famers in Kenya. Despite its importance, the recommended fertilizer levels for obtaining the maximum size distribution of the potato tuber have not been established in the rain-fed regions of Western Kenya. The main objective of this study was to optimize the size distribution of potato tuber using a second order rotatable design. The specific objective was to examine the effects of the factors potassium, nitrogen and phosphorous on the size distribution of potato tuber. This study presents an application of the RSM on the optimization of the size distribution of potato tuber using a three-factor central composite design (CCD). Ridge analysis method employed located the minimum levels of the factors K, N and P for size distribution of potato tuber as follows; K  44.82 Kg K O 2 ha1 , N  59.34 Kg N ha1 and P  180.94 Kg 2 5 P O ha1 respectively giving a minimum size distribution of 14.67 cm. Results revealed that potassium and nitrogen had a significant positive quadratic effect on the size distribution of potato tuber. Similarly, the interaction of the factors, potassium and nitrogen showed a significant positive effect on the size distribution of potato tuber. The findings obtained in this study have given the recommended fertilizer rates to be employed by both smallholder and large-scale farmers in Western Kenya.

Full Text: PDF