Native plant growth-promoting rhizobacteria influence selected soil properties and cocoa seedling development under nursery conditions in Western Boyacá, Colombia

Bioinoculant production requires multidisciplinary expertise to ensure reliable field performance. This study evaluated four native rhizobacterial isolates from the cocoa rhizosphere for inclusion in biofertilizing microbial consortia, assessing effects on soil enzymatic activity, physicochemical properties, and dasometric variables under nursery conditions in Pauna, Boyacá - Colombia. Seven treatments were compared: two native consortia (single-dose and serial application), a commercial inoculant, a chemical fertilizer, and an uninoculated control, using a completely randomized design with five replicate blocks of 20 plants per treatment. Three composite soil samples per treatment were analyzed at 0 and 6 months. Native consortia comprised phosphorus-solubilizing Serratia spp. and plant growth-promoting Pseudomonas spp., while the commercial inoculant contained Azotobacter chroococcum and Pseudomonas fluorescens. Molecular characterization revealed high functional redundancy among the selected strains, with strong potential for phosphate solubilization, colonization, and growth promotion, consistent with overlapping ecological niches. Bioinoculants slightly increased cellulase activity, organic carbon, total nitrogen, and organic matter, whereas chemical fertilization enhanced available phosphorus and exchangeable magnesium while lowering pH. Only boron, pH, phosphorus, and magnesium differed significantly among treatments (p < 0.05). Multivariate analysis linked bioinoculants to greater enzymatic and organic matter variability, and fertilizers to higher C/N ratio and phosphorus. Dasometric traits remained unaffected, indicating treatment-specific substrate effects favoring plant growth, pending field-scale validation. Limitations include the nursery-only setting, six-month evaluation period, and lack of field/biosafety validation.