Does Azospirillum brasilense mitigate water stress and reduce the use of nitrogen fertilizers in maize?

To determine whether Azospirillum brasilense mitigates water stress and lowers nitrogen fertilizer consump-tion in maize, physiology (pigments, nitrate reductase gas exchange, and water potential), macro/micronu-trients, root shape, and biomass were studied. The experiment was carried out in a greenhouse and included seven treatments and four replications. Plants under water deficits were inoculated with Azospirillum strains (Az1 and Az2) under two nitrogen fertilization conditions (20 and 120 kg ha-1) and compared to control plants (with irrigation and fertilization of 120 kg ha-1 without inoculation). Inoculation with Az1 increased the pigment content under water stress, mainly in the 120 kg ha-1 nitrogen treatment. The maize root sys-tem showed the best response to inoculation with A. brasilense. The plants with inoculant Az1 at 120 kg ha-1 N responded similar to the control plants, which were under ideal growing conditions for length, sur-face area, root diameter and shoot and root dry mass. Inoculation with A. brasilense Az1 and 120 kg ha-1 nitrogen under water stress improved the physiology and root morphology of maize. However, the use of inoculation does not replace nitrogen fertilization in maize, and the possible reasons and consequences are discussed. Inoculation of plants with A. brasilense is an effective strategy that should be applied in maize pro-duction.(c) 2023 Published by Elsevier B.V. on behalf of SAAB.