Silicon Alleviates Nitrogen Deficiency in Maize Without Additive Effects with Azospirillum brasilense

Abstract An efficient strategy to increase plant tolerance to nitrogen (N) deficiency would be the use of silicon (Si), which could be enhanced with the use of Azospirillum brasilense . However, the effects of this combination are not known in maize grown in nutrient solution. Thus, it was hypothesized that the combination of A. brasilense and Si may result in an additive effect on alleviating N deficiency in maize plants grown in nutrient solution. The objectives of this study were to evaluate the role of Si and A. brasiliense , both isolated and combined, in the nutritional, physiological and growth aspects of maize plants with N sufficiency and deficiency. The maize plants were grown in a greenhouse in pots with washed sand as the substrate. A randomized block experimental design with four replicates and eight treatments was used as follows T1: N sufficiency (+ N); T2: N deficiency (-N); T3: +N + A. brasiliense ; T4: -N + A. brasiliense ; T5: +N + Si; T6: -N + Si; T7: +N + A. brasiliense + Si; T8: -N + A. brasiliense + Si. A. brasiliense was supplied via seed treatment and Si via nutrient solution. In N sufficiency, both A. brasiliense and Si, alone or in combination, did not result in changes in plant growth; in N deficiency, only Si resulted in increased dry matter production of the shoots and roots, with no additive effects when combined with A. brasiliense . In conclusion, Si via nutrient solution is a good strategy to improve N nutrition efficiency, without additional effects from the use of A. brasilense via seed treatment. Graphical Abstract