The synergistic effects of a microbial consortium and sodium EDTA on cadmium detoxification and the antioxidant defense system in forage sorghum (Sorghum bicolor L.)

The intensifying contamination of agricultural soils with cadmium has heightened the need for sustainable strategies to alleviate oxidative stress and improve the physiological performance of plants. Microbial consortia and chelating agents are among the emerging approaches considered effective for managing this stress. The aim of this study was to investigate the effects of plant growth-promoting bacteria (Pantoea agglomerans and Pseudomonas fluorescens), arbuscular mycorrhizal fungi, and sodium EDTA on growth indices, photosynthetic pigments, and antioxidant enzyme activities of forage sorghum (Sorghum bicolor L.) grown in soil contaminated with ۴۰ mg kg⁻¹ cadmium sulfate. The experiment was conducted in a factorial arrangement based on a completely randomized design with four replications. Results showed that the triple interaction among bacterial inoculation, mycorrhizal symbiosis, and sodium EDTA was significant for seedling emergence percentage, chlorophyll b content, and antioxidant enzyme activities. The highest seedling emergence percentage was observed in the P. agglomerans × no mycorrhiza × no sodium EDTA treatment, showing a ۳۱.۷۲% increase compared with the control. Superoxide dismutase (SOD) activity increased by ۲۲.۱۷% in the P. fluorescens × mycorrhiza × no sodium EDTA treatment, while peroxidase (POD) activity was ۴۹.۵% higher in P. fluorescens × no mycorrhiza × sodium EDTA compared to the control. Mycorrhiza alone enhanced leaf soluble protein and total chlorophyll content by ۷.۴% and ۹.۱۳%, respectively. The highest carotenoid content was obtained in the P. agglomerans × sodium EDTA treatment, with a ۳.۱۳% increase over the control. Overall, the combination of P. fluorescens with mycorrhiza, without sodium EDTA, produced the most substantial improvements in the plant’s defense mechanisms and the preservation of photosynthetic pigments. Therefore, the synergistic application of beneficial microorganisms can be proposed as a sustainable and eco-friendly strategy to mitigate cadmium toxicity and enhance the phytoremediation potential of forage sorghum.

کلیدواژه ها:

Bioremediation ، Heavy Metals ، Microbial Symbiosis ، Oxidative Stress ، Physiological Response ، Rhizosphere ، استرس اکسیداتیو ، پالایش زیستی ، پاسخ فیزیولوژیک ، ریزوسفر ، فلزات سنگین ، هم زیستی میکروبی