Role of Nodulation-Enhancing Rhizobacteria in the Promotion of <i>Medicago sativa</i> Development in Nutrient-Poor Soils
2022
Noris J. Flores-Duarte | Enrique Mateos-Naranjo | Susana Redondo-Gómez | Eloísa Pajuelo | Ignacio D. Rodriguez-Llorente | Salvadora Navarro-Torre
Legumes are usually used as cover crops to improve soil quality due to the biological nitrogen fixation that occurs due to the interaction of legumes and rhizobia. This symbiosis can be used to recover degraded soils using legumes as pioneer plants. In this work, we screened for bacteria that improve the legume–rhizobia interaction in nutrient-poor soils. Fourteen phosphate solubilizer-strains were isolated, showing at least three out of the five tested plant growth promoting properties. Furthermore, cellulase, protease, pectinase, and chitinase activities were detected in three of the isolated strains. <i>Pseudomonas</i> sp. L1, <i>Chryseobacterium soli</i> L2, and <i>Priestia megaterium</i> L3 were selected to inoculate seeds and plants of <i>Medicago sativa</i> using a nutrient-poor soil as substrate under greenhouse conditions. The effects of the three bacteria individually and in <i>consortium</i> showed more vigorous plants with increased numbers of nodules and a higher nitrogen content than non-inoculated plants. Moreover, bacterial inoculation increased plants’ antioxidant activities and improved their development in nutrient-poor soils, suggesting an important role in the stress mechanisms of plants. In conclusion, the selected strains are nodulation-enhancing rhizobacteria that improve leguminous plants growth and nodulation in nutrient-poor soils and could be used by sustainable agriculture to promote plants’ development in degraded soils.
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