Azospirilla and Nitrogen Fertilization to Promote Maize Seed Development and Yield

Aims: This study evaluated the interaction of Azospirillum brasilense (Ab) strains and nitrogen fertilizer doses on maize.

Study Design: Laboratory experiment evaluated Ab strains (PCR and PTF) on maize seed germination and vigor (completely randomized design). Field experiment evaluated Ab strains and nitrogen fertilization on maize yield parameters (randomized block design).

Place and Duration of Study: The germination and vigor experiment (10 days in April 2019) was implemented in a controlled environment at the Seed Analysis Laboratory of the Universidade Federal de Uberlândia, Brazil. The field experiment (137 days in winter 2019) was implemented at the Fisioplant Research Station (Uberlândia, Brazil) under commercial maize crop management.

Methodology: In controlled conditions (laboratory), 200 seeds of maize (K9105VIP3, Riber KWS Seeds) were incubated (25 °C) with the Ab strain solutions for germination and vigor evaluations. In the field, 60,000 plants ha-1 (0.5 m space between sowing lines) of maize were cropped under combinations of nitrogen fertilizer and volumes of Ab strains (treatments) for leaf nitrogen, SPAD index, leaf count, fresh and dry maize shoot biomass, one-thousand grains weight, grain rows per maize ear, productivity (kg ha-1).

Results: Treatment with 100 mL ha-1 of Ab PFT strain increased maize seed germination and vigor more than Ab PCR strain and control (no-inoculation or fertilizer). The number of grain rows of the 100% N + 150 mL ha-1 of Ab PFT strain and the maize shoot dry mass of the 100% N (no-inoculation) were higher than the control. The treatments did not affect the SPAD index, weight of one thousand grains, fresh maize shoot biomass, or productivity.

Conclusion: Using Ab with nitrogen fertilizer is a promising strategy to improve maize crop responses; however, more studies are needed to detail the ideal management of Ab strains for maize crops and yield construction.