This study evaluated whether Azospirillum brasilense can complement mineral N fertilization and improve tomato performance under saline conditions. Tomato plants were inoculated with either the wild-type A. brasilense Sp7 (N-fixing) or its nitrogenase-deficient mutant Nif- (non-N-fixing) and exposed to NaCl concentrations ranging from 0 to 120 mM. At moderate salinity (30–90 mM NaCl), Sp7 inoculation enhanced root development,...