Field-based evaluation of multi-strain PGPR to improve zea mays yield and soil nutrient dynamics in semi-arid of Türkiye.

Soil fertility decline and overuse of agrochemicals threaten sustainable maize (Zea mays L.) production in semi-arid regions of Türkiye. Plant growth-promoting bacteria (PGPB) offer a biologically based alternative by enhancing nutrient uptake, root development, and soil health. In this field-based study, we evaluated the effects of a five-strain PGPR consortium (Azotobacter spp., Bacillus sp., Paenibacillus sp., Pantoea sp., and Pseudomonas sp.) on maize productivity and soil nutrient dynamics. A randomized split-plot design was used, involving four commercial maize hybrids and four inoculant doses (0, 100, 130, 160 mL/da). PGPR application significantly improved soil organic matter, phosphorus availability, and cation exchange capacity, particularly at the tasseling stage. The 130 mL/da dose yielded the highest grain productivity, suggesting optimized biological nitrogen fixation and water-use efficiency. Leaf analysis at the V15 stage revealed genotype-specific nutrient responses and elevated Zn and Cu levels under inoculated treatments, indicating enhanced micronutrient solubilization but also potential risk of nutrient imbalance. Our findings support the use of non-commercial, field-formulated PGPR consortia as a scalable component of sustainable maize systems, especially under climate-stressed conditions. The cultivar × dose interaction underscores the need for genotype-specific microbial strategies in precision agriculture.