Microbial inoculants supporting sorghum (Sorghum bicolor) under low water and nitrogen supplies in the Brazilian drylands

This study investigated the interactive effects of nitrogen (N) fertilization and water supply across distinct microbial treatments in sorghum ( Sorghum bicolor ). A factorial experiment was conducted under field conditions with different microbial strains, nitrogen application rates (20 and 140 kg N ha −1 ), and two water availability levels (45 % and 100 % evapotranspiration, ET C) . Results indicate that N fertilization, irrigation level, and microbial inoculation significantly influenced aboveground biomass production and the efficiency of N fertilization under the different levels of nitrogen fertilization, water supply, and microbial inoculation tested, highlighting those inoculants with Bacillus spp. ESA 13 and ESA 402, Rhizobium sp. ESA 15, Agrobacterium sp. ESA 441, and Herbaspirillum seropedicae BR 11417. Triple interaction also influenced potassium (K) uptake, while water supply and microbial inoculation influenced the extraction of N, calcium, Cu, and Zn from the soil. The plant height, stem diameter, and leaf area index were influenced by different bacteria and water supply when Pelomonas sp. ESA 424, Azospirillum baldaniorum BR 11005 T , and the yeast Meyerozyma sp. ESA 37 stood out in two (out of three) parameters under the most detrimental condition (45 % ET C and 20 kg N ha −1 ). These findings suggest the potential of the bacteria and yeasts tested to undergo further field assays using inoculants with more than one strain, each with complementary mechanisms, to enhance crop resilience and productivity in semiarid regions. • Microbial inoculation improves sorghum yield under low water and N supply. • Nutrient uptake is influenced by microbial inoculation. • A multiple microbe inoculant should be assessed as a synthetic community.