Abstract

The efficiency of applied phosphorus rarely exceeds 30% due to fixation in soil; it is also lost as a result of run-off and leaching, leaving as little as 10–20% available for plant utilization. The study was aimed at isolating and characterizing phosphate-solubilizing bacteria and their application as growth-promoting agent for maize cultivation. Composite soil samples were collected from three (3) different soils around the plant roots while brackish water was collected from the New Calabar River. Maize (Zea mays) seeds were purchased from Mile 3 Market, Port Harcourt, for the analysis. The seeds were cultured according to the standard microbiological procedures using Pikovskaya medium (PVK) and Nutrient agar (NA). Isolates were identified and screened for their phosphate-solubilizing potential. Bacteria with higher solubilizing potential were applied to grow maize seedlings. The results showed that soil samples contained high populations of heterotrophic and phosphate-solubilizing bacteria (PSB), with PSB counts ranging from 1.85×10⁴±0.36 to 1.57×10⁵±0.55CFU/g, and heterotrophic counts ranged from 3.49×10⁴±0.43 to 4.80×10⁶±0.14CFU/g, while brackish water had the lowest bacterial population. The phosphate solubilizing index (PSI) ranged from 2.0±0.03 to 3.0±0.04, with Pseudomonas spp. showing the highest solubilizing ability and Staphylococcus spp. the lowest. Maize plants inoculated with a consortium of Enterobacter, Bacillus, and Pseudomonas recorded the best growth performance with highest plant height of 178.5cm, leaf number of 12, leaf length of 94cm, and earliest fruiting at week 7. Among single-strain treatments, Bacillus promoted the highest plant height, leaf number, and fruit production at 8 weeks, while Pseudomonas showed the greatest leaf length. Enterobacter performed moderately, whereas NPK and the control recorded the lowest growth metrics across all parameters following its normal growth duration. Notably, fruiting was first observed in the PSB consortium treatment in week 7, while plants treated with single PSB cultures of Pseudomonas, Bacillus, or Enterobacter began fruiting at week 8. The phosphate-solubilizing bacteria (PSB) consortium demonstrated superior growth-promoting effects on maize compared to single isolates, NPK, and the control; by not only enhancing plant height, leaf number, and leaf length but also accelerating fruit production, indicating its potential as an efficient biofertilizer for improved maize productivity.