Improving growth of stockplants and rooting ability of leafy stem cuttings of Allanblackia floribunda Oliver (Clusiaceae) using different NPK fertilizers and periods of application

Our study addressed the effect of granular NPK 20-10-10 doses (0, 25 and 50 g/plant) applied to A. floribunda stockplants on growth of stockplant and the effect on rooting ability of foliar NPKs (15-15-30, 20-20-20 and 30-10-10) applied on leafy stem cuttings in propagators at different physiological stages of rooting process (setting, callus initiation and both). Results show that fertilizer doses significantly (p = 0.03) affect the number of cuttings that could be produced by stockplants 6 months after application. The mean number of cuttings per plant increased with fertilizer doses with the highest value of 11.06 +/- 0.41 % for 50 g. Application of NPK 20-20-20 foliar fertilizer on stem cuttings at callus stage, significantly (p = 0.04) boosted rooting of stem cuttings after 28 weeks (85.71 +/- 4.1 %). Number of roots per cutting was not significantly different (p = 0.98). However, the highest frequency of cuttings displayed three roots was observed on NPK 20-20-20 (To + Cal) and NPK 30-10-10 (To + Cal). From this study, we can conclude that, 50 g of NPK 20-10-10 fertilizer application on stockplants produced the greatest number of vegetal material. Treated with NPK 20-20-20 at callus initiation stage or both (i. e. at setting and at callus initiation stage), rooting performs better