Soil beneficial bacteria: Harnessing tools for optimizing citrus growth and soil health in pH‐stressed soils

Rhizosphere bacteria can support crop production by promoting plant health, soil fertility, and resilience to biotic and abiotic stresses. However, the potential role of soil-beneficial bacteria, particularly plant growth-promoting rhizobacteria (PGPR), remains inadequately explored in citrus production grown on pH-stressed soil. This study aimed to evaluate the effect of PGPR on citrus growth and soil health indicators under pH-stressed Florida sandy soil. A greenhouse study was conducted at the University of Florida, Lake Alfred, which followed a 3 × 3 factorial randomized complete block design with three soil pH levels (5.0, 6.5, and 8.0) and three PGPR (P)/fertilizer (F) combinations (P + 75% F, P + 100% F, and 100% F only). Soil pH conditions were adjusted using a soil neutralization curve generated by soil incubation methods. The results showed that the soil pH factor significantly influenced most crop growth parameters, with optimal results at a pH of 6.5. PGPR significantly (p < 0.05) improved the plant height (27.84 cm), root mass density (7.65 mg/cm³), stem diameter (4.89 mm), and aboveground biomass (2.64 g/ plant) compared to without PGPR application. No significant difference between 75% and 100% fertilizer rates were found in crop and soil attributes when PGPR was applied. Soil organic matter and microbial respiration were also significantly improved (p < 0.05) with PGPR inoculation by 1.15 and 1.65 folds, respectively, compared to 100% F-only treatment. The availability of soil nutrients was influenced by PGPR treatments, which likely enhanced nutrient uptake and improved crop growth even with a reduced fertilizer rate. The results suggested that PGPR inoculation combined with partial fertilization can improve soil health indicators and plant growth, even in pH-stressed sandy soils.