NPK Fertilizer Requirements for Jatropha Zeyheri Indigenous Tea under Microplot Conditions

Abstract

Effects of NPK fertilizer could have positive or negative effects in relation to growth of crops under certain environments, with minimum findings on how crops react to fertilizers under microplot conditions. Therefore, the objective of this study was to assess the effects of increasing NPK fertilizer rate on Jatropha zeyheri tea growth under microplot conditions. At two-leaf phase, J. zeyheri seedlings were transplanted into 25 cm diameter plastic pots. Each pot was filled with heated pasteurized sandy soil and Hygromix at 3:1 (v/v) ratio and placed in a spacing of 0.30 m × 0.30 m inter-and intra-row spacing. Six treatments constituting NPK fertilizer rates (0, 2, 4, 8, 16 and 32 g) were arranged in a randomized complete block design, with five replications. Treatments were initiated a week after transplanting, and 130 days after that, treatments had highly significant effects on leaf width, contributing 66% in TTV, whereas significant effects were reported on vine length, stem diameter, leaf length and dry root mass contributing 61, 67, 68 and 49% in TTV, respectively. NPK fertilizer rates did not affect chlorophyll content, NDVI, dry shoot mass, number of leaves and leaf area index. Jatropha zeyheri yield variables when exposed to increasing fertilizer rates displayed positive quadratic relations. Use of fertilizers had setbacks when applied inappropriately leading to inconsistent results. However, determining optimum fertilizer requirement for J. zeyheri was a strategical solution for inappropriate application. Jatropha zeyheri fertilizer requirements were optimized at 3.30 g fertilizer/plant, which shows that J. zeyheri requires a minimum amount of NPK fertilizer to stimulate growth.