Phosphate solubilizing rhizobacteria inoculation to increase rock phosphates efficiency and improve maize growth

Abstract

Rock phosphates are less soluble and agronomically not as efficient as the acidulated. However, some rhizobacteria can improve the solubilization of inorganic phosphates in the soil, raising the efficiency of the rock phosphates. The objective was to evaluate the development of maize plants in response to the application of soluble and rock P sources associated with rhizobacteria inoculation. A greenhouse experiment was carried out with six P sources: no P application; ​​Triple Superphosphate (TSPh); Gafsa rock phosphate (reactive); Itafós rock phosphate (non-reactive); TSPh + Gafsa; and TSPh + Itafós, and three inoculation forms: no inoculation, Burkholderia pickettii GN 2214 and Pseudomonas sp. fluorescens group P21. Plant height, stem diameter, leaf area, shoot dry weight (ShDW), root dry weight (RDW), total dry weight, cumulative P content in ShDW, RDW/ShDW ratio and relative agronomic efficiency were assessed. Agronomic efficiency and growth of the TSPh-treated plants were better than of those treated with rock phosphates. The association of TSPh with rock phosphates increases the agronomic efficiency and maize plant growth more than the isolated rock sources. Inoculation with P. fluorescens strain P21, improved the performance of maize fertilized with Gafsa phosphate, but had no effect when associated with Itafós phosphate. Together with TSPh, inoculation intensified shoot and root growth, indicating the potential to increase the efficiency of soluble sources as well.