Enhancement of physiological, biochemical and quality traits in soybean (Glycine max L.) by bacterial consortia

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Aim To evaluate the effects of endophytic bacterial inoculation and their consortia on physiological traits, yield, zinc (Zn) biofortification, and grain quality of three Pant soybean varieties (PS26, PS25, and PS1347). Method A field experiment was conducted using individual bacterial isolates and two consortia: Consortium 1 [PLSD6 ( Pantoea ananatis ), PLSD1 ( Pseudomonas protegens ), and PSSI3 ( Pseudomonas moraviensis )] and Consortium 2 [SRK14 and MRCII6 ( Serratia marcescens )]. Physiological, biochemical, agronomic, and Zn-related parameters were recorded along with correlation and principal component analyses. Results Bacterial inoculation significantly improved physiological, biochemical, and agronomic traits. Consortium treatments accelerated flowering (40–42 days) and enhanced chlorophyll a (2.18 mg g −1 FW), chlorophyll b (2.48 mg g −1 FW), and carotenoids (0.89 mg g −1 FW). Gas exchange parameters including stomatal conductance (0.52 mol H₂O m −2 s −1 ), photosynthetic rate (19.75 μmol CO₂ m −2 s −1 ), internal CO₂ concentration (379.1 μmol mol −1 ), and transpiration rate (7.46 mmol H₂O m −2 s −1 ) also increased. These improvements resulted in higher plant height (60.80 cm) and seed yield (36.56 q ha −1 ). Soil Zn concentration increased from 1.27 to 1.72 to 3.22–3.59 mg kg −1 , while seed Zn content reached 28.30 mg kg −1 , indicating effective Zn solubilization and biofortification. Grain quality was enhanced through increased protein content (45.71%) and reduced phytic acid (0.90%). Correlation and principal component analyses revealed positive associations among physiological traits, Zn accumulation, yield, and protein content, whereas phytic acid showed negative correlations. Conclusion Consortium 1 effectively improved soybean productivity, Zn biofortification, and grain quality, demonstrating the potential of microbial consortia as sustainable biofortification strategy.