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Potential application of selected phosphate solubilizing bacteria isolated from Chenopodium quinoa Willd rhizosphere in early plant growth promotion

 Ismail MAHDI  

 To meet the worldwide demand for food, smart management of arable lands is needed. This could be achieved through sustainable approaches such as the use of plant growth-promoting microorganisms including bacteria. Phosphate (P) solubilization is one of the major mechanisms of plant growth promotion by associated bacteria. In the present study, we isolated and screened 14 strains from the rhizosphere of Chenopodium quinoa Willd grown in the experimental farm of UM6P and assessed their plant growth promoting properties. Next, they were identified using 16S rRNA and Cpn60 genes sequencing as Bacillus, Pseudomonas and Enterobacter. These strains showed dispersed capacities to solubilize P (up to 346 mg L−1) following 5 days of incubation in NBRIP broth. We also assessed their abilities for indole acetic acid (IAA) production (up to 795,3 µg ml−1) and in vitro salt tolerance. Three Bacillus strains QA1, QA2, and S8 tolerated high salt stress induced by NaCl with a maximum tolerable concentration of 8%. Three performant isolates, QA1, S6 and QF11, were further selected for seed germination assay because of their pronounced abilities in terms of P solubilization, IAA production and salt tolerance. The early plant growth potential of tested strains showed that inoculated Quinoa seeds displayed greater germination rate and higher seedlings growth under bacterial treatments. The positive effect on seed germination traits strongly suggest that tested strains are growth promoting, halotolerant and P solubilizing bacteria which could be exploited as biofertilizers.