Inoculation with Bacillus velezensis UFV 3918 Promotes Early Growth and Nutrient Uptake in Sugarcane Under Reduced Phosphorus Fertilization

Phosphorus (P) is one of the main limiting factors for sugarcane establishment and longevity in tropical soils, requiring biotechnological strategies to improve fertilizer use efficiency. This study evaluated the effects of inoculation with Bacillus velezensis UFV 3918, alone or combined with reduced monoammonium phosphate (MAP) doses, on the morphological, nutritional, and root nutrient uptake responses of sugarcane grown in a dystrophic Red Latosol under greenhouse conditions. The experiment was conducted in a completely randomized design with six treatments and four replicates: absolute control (AC, without MAP), commercial control (CC, recommended MAP dose), B. velezensis alone (Bv), and Bv combined with 1/3, 2/3, or the full recommended MAP dose. Plant growth responses varied across treatments and stages, with Bv promoting greater leaf area than the CC at 120 and 180 DAP, whereas Bv + 1/3 MAP maintained leaf area comparable to the CC throughout the evaluation period. Principal component analysis (PCA) revealed a clear separation among treatments, with Bv exhibiting the most distinct plant response, primarily associated with greater stalk diameter, root and stalk biomass, higher concentrations of potassium and phosphorus in stalks, sulfur and magnesium in roots, and greater boron-use efficiency. Bv + 1/3 MAP displayed an intermediate multivariate profile, mainly associated with phosphorus uptake per unit root length and nutritional attributes related to phosphorus acquisition under reduced fertilizer supply. Correlation analysis further revealed strong positive associations among growth-related traits, biomass accumulation, and phosphorus-related variables, indicating a close relationship between P acquisition and plant responses to bacterial inoculation. Overall, inoculation with B. velezensis UFV 3918 improved early sugarcane growth and nutrient acquisition, and its combination with 1/3 of the recommended MAP rate maintained plant performance. These findings indicate the potential for reducing mineral P inputs during early sugarcane establishment; however, long-term field trials are required to determine whether these responses can be sustained throughout the crop cycle and under commercial production conditions.