Improving phosphorus utilization and iron homeostasis in maize through nitrification inhibitors and plant growth-promoting bacterium

Introduction This study aimed to investigate the effects of nitrification inhibitors (NIs), specifically DMPP (Dimethyl pyrazole phosphate) and DMPFA (Dimethyl pyrazole fulvic acid), and plant growth-promoting microorganisms (PGPM) on nutrient uptake, allocation, and plant growth in maize under low phosphorus (P) availability. The research questions explored whether NIs enhance P, manganese (Mn), and zinc (Zn) uptake through rhizosphere acidification, alter nutrient partitioning between roots and shoots, and whether DMPFA-PGPM combinations synergistically improve plant growth and nutrient acquisition. Methods Two rhizobox experiments were conducted using silt loam soil with low P content (8.7 mg kg −1 P-CAL, pH 6.4). Results In the first experiment, maize was subjected to ten treatments, including ammonium (NH 4 + ) and nitrate (NO3 −) with or without DMPP, DMPFA, and rock phosphate (RP), compared to controls. The second experiment tested five treatments, including NH 4 + with DMPFA, fulvic acid, and Bacillus atrophaeus (ABi05) as PGPM. Measurements included rhizosphere pH, acid/alkaline phosphatase activity, root exudates, phytohormones, root morphology, plant biomass, and nutrient (P, Mn, Zn, Fe, Ca, Mg, K) concentrations in shoots and roots. Nutrient use efficiencies (PUE, PFPp, NRE) were calculated, and data were analyzed using one-way ANOVA with Fisher’s LSD test (p