Plant growth-promoting bacteria belonging to the genera Pseudomonas and Bacillus improve the growth of sorghum seedings in a low-nutrient soil

Background: Deficiency in sorghum growth in ecosystems of low-nutrient soils has been scarcely studied. This soil deficiency can be overcome by the addition of plant growth-promoting bacteria which increase sorghum growth. Questions and/or Hypotheses: indole acetic acid (IAA) producing and phosphate solubilizing bacteria can promote sorghum growth under nutritional stress. Studied species: Sorghum bicolor (L.) Moench. Study site and dates: Mexico City, 2018. Methods: Of the twelve bacterial strains utilized, three produce IAA (group BI), two strains produce IAA and siderophores (BIS group), four strains produce IAA and solubilize phosphate (BIP group), and three strains produce IAA, solubilize phosphate, and produce siderophores (BIPS group). Hydroponic bioassays and low-nutrient soil bioassay were used. Results: In hydroponic bioassays, for BI and BIS groups, five strains significantly increased the growth parameters with respect to the control, and for the BIP and BIPS groups, two strains promoted stem development and shoot dry weight. In a low-nutrient soil bioassay, Pseudomonas sp. BI-1 (from BI group) was the one that presented the highest percentages 32, 48, 140 and 79 % in stem diameter, height and dry weight of the shoot and dry weight of the root, respectively, followed by the P. mohnii BIPS-10 strain (from BIPS group) that exhibited similar results. Conclusions: IAA producing Pseudomonas strains improve the sorghum growth in a low-nutrient soil and suggest thatPseudomonas sp. BI-1 and P. mohnii BIPS-10 could be used as potential bioinoculants for sorghum. Antecedentes: La deficiencia en el crecimiento del sorgo en suelos con nutrientes escasos es poco estudiada. Esta deficiencia puede superarse mediante la adición de bacterias promotoras del crecimiento vegetal que aumentan el crecimiento del sorgo. Preguntas y/o hipótesis: bacterias que producen ácido indol acético (IAA) y solubilizan fosfato promueven el crecimiento del sorgo bajo estrés nutricional. Especies de estudio: Sorghum bicolor (L.) Moench. Sitio y años de estudio: Ciudad de México, 2018. Métodos: de doce bacterias utilizadas, tres producen IAA (grupo BI), dos producen IAA y sideróforos (grupo BIS), cuatro producen IAA y solubilizan fosfato (grupo BIP), y tres producen IAA, solubilizan fosfato y producen sideróforos (grupo BIPS). Bioensayos hidropónicos y bioensayos en suelo con nutrientes escasos fueron empleados. Resultados: en los bioensayos hidropónicos, para los grupos BI y BIS, c