Effect of Rhizobacteria Isolated from the Rhizosphere of Solanum lycopersicum L. on Tomato Seed Germination

Plant growth-promoting rhizobacteria (PGPR) are a group of bacteria that colonize plant roots without causing any damage and contribute to seed germination and plant development through mechanisms such as indole-3-acetic acid (IAA) production and phosphate solubilization. 10 isolates from the rhizosphere of Solanum lycopersicum L. (Ayas tomatoes) were identified using MALDI-TOF-MS to investigate morphology, biochemistry, and plant growth-promoting traits (phosphate solubilization and IAA production) in this study. Among all isolates, four (DMTS-2, DMTS-4, DMTS-6, DMTS-10) produced IAA, while five (DMTS-2, DMTS-4, DMTS-6, DMTS-7, DMTS-9) solubilized inorganic phosphate. Three isolates (DMTS-2, DMTS-4, and DMTS-6), solubilized both inorganic phosphate and produced IAA. They were selected for germination testing in this study. Furthermore, three rhizospheric bacterial isolates (DMTS-2, DMTS-4, and DMTS-6) were inoculated onto tomato seeds and monitored in a Petri dish assay at 25 °C for 14 days. The experiment was conducted using a randomized block design with three replicates, each comprising 20 seeds. The results demonstrated that the three selected indigenous rhizobacterial treatments had a significantly positive effect on germination percentage, vigor index, and seedling growth parameters over 14 days compared with the untreated control. The highest vigor index and germination percentage increases were observed in isolate DMTS-4, with a vigor index of 425.1 and a germination percentage of 65.4%. This study clearly demonstrated that the selected local isolates (DMTS-2, DMTS-4, and DMTS-6) enhanced the germination success of Solanum lycopersicum through their abilities to produce IAA and solubilize inorganic phosphate.