Farmyard manure and arbuscular mycorrhiza fungi inoculation enhanced growth and fruit fibre productivity of Calotropis procera in semi-arid eastern Kenya

A greenhouse experiment was conducted at the South Eastern Kenya University (SEKU) to determine the effects of farmyard manure (FYM) and arbuscular mycorrhiza fungi (AMF) inoculation on growth, vigor, shoot nutrient uptake (SNU) and AMF root colonization percentage (RC%) of potted Calotropis procera (Calotropis) seedlings. A field trial was laid out to determine the effects of the treatments on growth and fruit fibre productivity of the transplanted seedlings. The experiments were laid out in a split-split-plot design with a 2*2*2 factorial arrangement and 3 replications. The main plot factor constituted 2 Kenyan Calotropis provenances, Kibwezi and Tharaka. The sub-plot factor comprised of FYM and without FYM application while the sub-sub-plot factor involved inoculation with mixed strains of commercial AMF and without inoculation. Farmyard manure (FYM) and the integration of FYM and AMF inoculation (FYM*AMF) significantly improved Calotropis seedlings’ growth, vigor, SNU and AMF RC% in the greenhouse. However, FYM*AMF was comparatively superior to solely FYM and AMF. There were positive correlations of AMF RC% with growth, shoot dry weight (SDW) and SNU of the seedlings at the end of the greenhouse experiment. Under field conditions, FYM and FYM*AMF significantly enhanced growth and fruit fibre productivity of Calotropis plants than the controls, barring a few cases. The study recommends the use of FYM and FYM*AMF in Calotropis seedlings’ production in the drylands of Kenya. Future research should investigate the persistence of the introduced commercial AMF strains in the soil using molecular techniques.