Impact of Azospirillum Brasilense and Penicillium sp. Inoculation on Maize Productivity in the Brazilian Cerrado

The use of microbial inoculants has increased markedly in recent years, driven by the need to enhance productivity and reduce reliance on chemical inputs in cultivating maize. This study aimed to evaluate the impact of Azospirillum brasilense and Penicillium sp. inoculation on maize productivity and economic feasibility in the Brazilian Cerrado, in association with different doses of nitrogen, phosphorus, and potassium (NPK). An in vitro phosphate solubilization test was conducted for isolate selection. Two field experiments were conducted during the second crop of the 2017/18 and 2018/19 agricultural seasons in Rio Verde, Goiás, Brazil, following a randomized block design in a 4 × 4 factorial scheme (four increasing NPK doses- 30, 60, 90, and 120% of the recommended dose; four inoculation treatments- non-inoculated control, A. brasilense inoculation, Penicillium sp. inoculation, and co-inoculation with both A. brasilense and Penicillium sp.). Grain yield was determined at harvest (kg ha⁻¹). For economic analysis, the costs of NPK fertilization and inoculants were considered, while productivity was converted to gross and net yield based on operating costs. The results showed that both Aspergillus sp. and Penicillium sp. can solubilize Bayóvar natural phosphate under in vitro conditions, with Penicillium sp. exhibiting a greater ability to do so. The co-inoculation of A. brasilense and Penicillium sp. enhanced maize yield and allowed a reduction in standard NPK doses, thereby reducing overall production costs.