Biochemical activity and bioassay on maize seedling of selected indigenous phosphate-solubilizing bacteria isolated from the acid soil ecosystem

Phosphorus availability is the major constraint for plant growth in the acid soil ecosystem, due to high fixation by Al and Fe. Microbial fertilizers such as phosphate-solubilizing bacteria (PSB) can increase P availability in soils for root uptake. The objective of the research was to verify the ability of four isolates of PSB isolated from acid soil to solubilize unavailable inorganic phosphate, produce phosphatase, malic acid and indole acetic acid (IAA), as well as increase plant height of maize seedling. The bioassay by growing maize seedling in liquid nutrients has been performed to study the response of seedling to PSB inoculation. The experimental design of bioassay was a randomized block design with five replications. The results showed that the isolates RR 1 and SPR 4 had a relatively high solubilizing index. Moreover, all the PSB isolates had the ability to produce phosphatase and IAA and dissolve P. The performance of PSB-inoculated seedling was better visually and the root length was increased by 66.7–74.5% compared to the control. This result concludes that the species of four isolates needs to be identified by a biomolecular method and formulated as biofertilizers for increasing the maize productivity in the acid soil ecosystem