Early Development and Phosphorus Use Efficiency Response to Phosphate Fertilizer Rates Associated with Phosphate-Solubilizing Bacteria in Contrasting Corn Hybrids

Corn (Zea mays L.) is a very sensitive crop to phosphorus (P) deficiency during the early development phase, which may be a limiting factor for the sustainable production of this crop in P-deficient tropical soils. However, scientific evidence indicates that inoculation with phosphate-solubilizing bacteria can improve the development, uptake, and P-use efficiency of corn plants. In the present study, two contrasting corn hybrids were investigated for their responsiveness to multiple inoculations of Bacillus subtilis, B. megaterium, B. velezencis, and Pseudomonas fluorescens and application of phosphate fertilizer rates in the sandy soil of the Brazilian Cerrado. Plants from stable (DKB 360 PRO3) and responsive (DKB 255 PRO3) corn hybrids were inoculated with 0 and 2 mL of inoculant containing multiple phosphate-solubilizing bacteria and fertilized with low (0 mg P·kg−1), medium (40 mg P·kg−1) and high (80 mg P·kg−1) levels of phosphate fertilizer using triple superphosphate (46% of P2O5). Treatments were distributed in a randomized block design using 2 × 2 × 3 factorial scheme, with four replicates. Plants were grown in 8-L pots for 70 days under greenhouse conditions. Morphological characteristics, leaf P concentration, and P use efficiency of corn plants were evaluated. Our results showed that the multiple inoculations of Bacillus subtilis, B. megaterium, B. velezencis, and Pseudomonas fluorescens are a promising sustainable agricultural practice to be recommended for corn cultivation, especially because it improves the development and P use efficiency of plants fertilized with medium P levels, which reduces the costs associated with mineral phosphate fertilization, a non-renewable fertilizer source. In sandy tropical soil with low P availability, applying intermediate rates of highly soluble phosphate fertilizer, such as triple superphosphate, is sufficient to maximize plant development and the nutritional status of corn crops for sustainable production with low environmental impact.