Influence of Plant Growth-Promoting Rhizobacteria on Maize Growth Under Different Fertility Sources.

Free living bacteria in the plant rhizosphere have the ability to mediate soil processes such as nitrogen fixation, mineralization, solubilization, and nutrient mobilization. Thus, inoculating seeds with bacteria known to promote plant growth may be a promising technique for enhancing nutrient use efficiency and improving crop production. Therefore, a study was conducted to evaluate the effects of plant growth-promoting rhizobacteria (PGPR) on root establishment and biomass production of maize (Zea mays L.) during the early growth stages using three fertility sources under greenhouse conditions. Treatments included three fertility sources (poultry litter, bio-solids, and urea) at 168 kg N ha^-1 and five PGPR inoculants (4 PGPR strain mixtures and 1 control without PGPR). Applying poultry litter significantly improved root morphological parameters, and increased plant biomass at the V4, V6, and VT growth stages when compared to the other fertility sources. At the V4 stage, PGPR stimulated root growth and enhanced aboveground biomass with urea and poultry litter, while no differences were observed with PGPR and bio-solids. At the V6 stage, poultry litter, bio-solids, and urea with PGPR significantly increased some growth parameters (e.g., plant height, leaf area, and root morphology). However, at the VT stage, PGPR’s influence on plant growth was minimal regardless of fertility source. Applying the fertilizers sources at a 168 kg ha^-1 may have masked PGPR’s influence on maize growth as the plants reached their later vegetative growth stages. Future research is needed to evaluate the influence of PGPR on plant growth when fertility requirements are not optimal.