Multifunctional fluorescent Pseudomonas: effects on maize development and tools for their selection

Maize is one of the most cultivated cereals worldwide. Despite the low nutrient availability in the soil, high amounts of fertilizers are applied causing economic and environmental impacts. Then, Plant Growth Promoting Rhizobacteria (PGPR) as Fluorescent Pseudomonas can be utilized as an alternative. The present work aims to analyze the effect of Pseudomonas isolates on maize development and production and verify the relationship between growth mechanisms and IAA production. Sixteen Pseudomonas isolates were tested in vitro to produce IAA, ACC deaminase, siderophores, and solubilize Fe and Al phosphates. Three isolates (CBSAL02, CBSAL05, and CBSAL06) were selected for the field experiment, in which an A. brasilense inoculant was the control, generating five treatments with four replications. More than 50% of the isolates demonstrated the tested mechanisms. Only CBSAL05 did not produce siderophore or could fix N. Inoculations with A. brasilense and Pseudomonas isolates increased leaf N content among the selected isolates. The CBSAL06 isolate increased productivity, thus demonstrating the potential use as an inoculant.