Phosphate solubilization potential of indigenous rhizosphere fungi and their biofertilizer formulations
¹Department of Microbiology, Faculty of Life Sciences, University of Ilorin, 1515 Ilorin, Nigeria
²Nigerian Stored Products Research Institute, 1489 Ibadan, Nigeria
³Independent Researcher, Edmonton, AB, Canada. T5X 0H2.
⁴Biomass & Bioenergy Research Group, Center for Sustainable Energy and Power Systems Research, Research Institute of Sciences and Engineering, University of Sharjah, 27272 Sharjah, United Arab Emirates
⁵Institute of Technology, Chair of Biosystems Engineering, Estonian University of Life Sciences, Kreutzwaldi 56, 51006 Tartu, Estonia
⁶Department of Agronomy, Faculty of Agriculture, University of Ilorin, 1515 Ilorin, Nigeria
The harmful effects of chemical fertilizers on soil, plants, and eco-systems have stimulated the growth of the global biofertilizer market. However, biofertilizer use remains limited in developing countries due to inadequate research and poor technology. The use of readily available materials for biofertilizer production can be a good starting point. This study aimed to investigate phosphate-solubilizing potentials of soil fungi and the shelf-life of their biofertilizer formulations using sawdust and charcoal as carriers. Soil samples from the rhizosphere were cultured on Pikovskaya (PVK) agar, and the best phosphate solubilizers (Aspergillus niger, Aspergillus fumigatus and A. flavus) were screened for their phosphate-solubilization potentials on solid medium. Results obtained showed that A. niger had the highest solubilization index of 1.72, followed by A. fumigatus, and A. flavus with a solubilization index of 1.01 and 0.95, respectively. Optimization studies showed that after 5 days of incubation, A. niger, A. flavus and A. fumigatus solubilized 149, 112 and 126 mg L-1 of phosphate, respectively. These values increased to 549 mg L-1 on day 11 for A. niger, 379 mg L-1 on day 9 for A. flavus and 430 mg L-1 on day 9 for A. fumigatus. Furthermore, A. fumigatus and A. flavus proved to be better inoculants than A. niger as they maintained higher CFU g-1 counts throughout the experiment. Also, sawdust supported higher counts of the three inoculants than charcoal and was thus the best carrier. The findings demonstrated that these aspergilli can be harnessed for improving soil fertility and plant development.