ABSTRACT
A screen house experiment was carried out to investigate the comparative effect of some fertilizers on plant growth promoting fungi in the rhizosphere of okra planted on degraded ultisols at the teaching and research farm of the University of Benin, Benin City, Edo State, Nigeria. Four treatments; poultry manure (PM), earthworm cast (EC), urea (N2) and control were laid out in in a completely randomized block design (CRBD) with three replications. Data was collected on plant growth (height, girth, number of leaves, leaf length (cm), leaf breadth (cm), leaf area (cm2)) and yield parameters of okra plant while the soils samples were analyzed for physical, chemical and microbial properties. The results from the experiment suggest that organic fertilizers used in this study (poultry manure, earthworm cast) positively influence the agronomic performance of the okra plant. It also showed that, the soil physical properties (texturally) remained unchanged but the exchangeable acidity Al (0.40 - 0.02 cmolkg-1), H (0.15 - 0.15 cmolkg-1), ECEC (2.501 - 4.60 cmolkg-1), Base saturation (78.11 - 96.37 cmolkg-1), Organic carbon (10.21-13.97gkg-1), exchangeable capacity (50.50-5.39uS/cm), organic matter (17.61-24.09gkg-1), pH (5.03-5.39), Total N(0.74-1.01), exchangeable bases Ca (0.99-2.70molkg-1), Mg (0.07-0.58cmolkg-1), Na (0.80-0.64cmolkg-1), K (0.08-0.53cmolkg-1), and available P (14.75-215.03mgkg-1). The fungi population slightly varied in numbers but was not significantly different from one treatment to the other. Control (C) had 3.49 x 10-6 cfug-1 while the treated soils (urea, earthworm cast and poultry manure) which recorded 3.43 x 10-6 cfug-1, 3.48 x 10-6 cfug-1 and 3.56x10-6 cfug-1 respectively. Fungi species; Trichoderma sp, Penicillium sp, Aspergillus niger has the ability to produce IAA and solubilize phosphate in the soil, while Cladosporium spp, Aspergillus flavus are not able to produce IAA and solubilize phosphate. PSI shows the phosphate solubilization index across the days in the fungi species Trichoderma sp (2.80-6.33cm), Aspergillus niger (2.00 - 4.52cm), Penicillium sp (1.60 - 3.62cm) Based on the findings of this experiment, it could be deduced that PM, EC fertilizers promotes higher performance of okra.
