© 2015, Springer International Publishing Switzerland. Background and aims: Plant-growth promoting rhizobacteria (PGPR) can promote plant performance under water deficit, but the physiology and biochemistry of the promoting process induced by PGPR under different water deficits is not well known in maize (Zea mays L). Methods: A glasshouse study was conducted to determine the effects of Burkholderia sp. LD-11 on morphophysiological traits for plant growth and homeostasis between reactive oxygen species (ROS) and antioxidant enzymes under five regimens in two maize inbred lines. Results: Soil inoculation with Burkholderia sp. LD-11 promoted biomass accumulation and improved instantaneous water-use efficiency (WUEi), regardless of the soil water availability. It also triggered production of indole-3-acetic acid (IAA), decreasing the accumulation of abscisic acid (ABA) induced by the water deficit, alleviated ROS accumulation, and resulted in a reduction in lipid peroxidation induced by the water deficits. Soil inoculation also enhanced the tolerance to water deficit through reducing stomatal aperture by increasing the sensitivity of stomatal conductance (gs) to small changes in ABA concentration in the leaves. Conclusions: Soil inoculation with Burkholderia sp. LD-11 enhanced root systems and WUEi, offering a potential avenue for improving maize tolerance to water deficit.