The use of rhizospheric SynComs can be a new and sustainable strategy in the agrobiotechnology sector. The objective of this study was to create the most appropriate SynCom composition; examine the ability to dissolve natural rock phosphate (RP) from Morocco in liquid-modified NBRIP medium; determine organic acids, and phytohormones; and verify plant growth promoting and nutrition uptake effect in the pot experiments of winter wheat (Triticum aestivum). A total of nine different microorganisms were isolated, which belonged to three different genera: Bacillus, Pseudomonas, and Streptomyces. Out of the 21 treatments tested, four SynComs had the best phosphate-dissolving properties: IJAK-27+44+91 (129.17 mg L⁻¹), IIBEI-32+40 (90.95 µg mL⁻¹), IIIDEG-45+41 (122.78 mg L⁻¹), and IIIDEG-45+41+72 (120.78 mg L⁻¹). We demonstrate that these SynComs are capable of producing lactic, acetic, gluconic, malic, oxalic, citric acids, and phytohormones such as indole-3-acetic acid, zeatin, gibberellic acid, and abscisic acid. In pot experiments with winter wheat, we also demonstrated that the designed SynComs were able to effectively colonize the plant root rhizosphere and contributed to more abundant plant growth characteristics and nutrient uptake as uninoculated treatment or uninoculated treatment with superphosphate (NPK 0-19-0). The obtained results show that the SynCom compositions of IJAK-27+44+91, IIBEI-32+40, IIIDEG-45+41, and IIIDEG-45+41+72 can be considered as promising candidates for developing biofertilizers to facilitate P absorption and increase plant nutrition.

The uneven effectiveness of rhizobia inoculants has increased interest in developing specific inoculants for each genotype. This study investigated the biological nitrogen fixation efficiency and competition between different Rhizobium leguminosarum strains in different pea genotypes, namely, “Egle DS” and “Respect”. The results showed that plant genotype was a significant factor determining competition and nitrogen fixation among R. leguminosarum strains. The most competitive R. leguminosarum LIN06 strain in the pea genotype “Egle DS” was characterized by a low nitrogen fixation efficiency, while the most competitive R. leguminosarum EGLE10 strain in the “Respect” genotype was characterized by a high biological nitrogen fixation efficiency. It was also found that the “Respect” genotype may prefer and form symbiotic relationships with more efficient nitrogen fixing strains, while the “Egle DS” genotype formed symbiotic relationships with less efficient strains. However, even less efficient strains had a significant positive effect on nitrogen accumulation in plants under natural conditions. Finally, our study showed that sophisticated tests and methods are not necessary to analyze the competitiveness of rhizobia; it is sufficient to analyze the effectiveness of bacterial strains on plants in unsterilized soil.