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چکیده
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Pseudomonas spp. are bacteria known for their ability to degrade various pesticides, acting as natural biofilters. Despite their widespread use, the degradation of metribuzin—a herbicide commonly applied in agriculture—by these bacterial strains remains undocumented. This investigation aims to assess the capacity of Pseudomonas spp. to alleviate metribuzin-induced stress in different wheat cultivars under precisely controlled environmental conditions, offering insights into potential bioremediation strategies. This experiment was conducted as factorial in a completely randomized design with three replications. It included varying concentrations of metribuzin (0, 5, 10, 15, 20, and 30 mg/kg), bacterial treatments (control, P. fluorescens, and P. aeruginosa), and wheat cultivars (Pishtaz, Chamran, and Sivand). The evaluation focused on plant growth and biochemical responses, monitored at ten-day intervals starting 14 days after planting (DAP). A strong dose-dependent inhibition of plant growth was observed with increasing metribuzin concentrations. Growth reduction intensified at concentrations above 20 mg/kg, but near-complete inhibition (EC90) generally required higher concentrations, depending on cultivar and bacterial treatment. Pishtaz demonstrated the highest level of herbicide tolerance, with EC90 values in the non-inoculated treatment ranging from 23 to 107 mg/kg across growth stages. Increases in antioxidant enzyme activities and decreases in malondialdehyde levels were observed, indicating the stress mitigation capabilities of Pseudomonas spp. through biodegradation, which also led to enhanced plant growth and increased bacterial colony numbers in the soil. Variability in metribuzin sensitivity was observed among the cultivars, with Pishtaz being notably tolerant, Chamran semi-sensitive, and Sivand sensitive. P. fluorescens, in particular, showed a marked ability to reduce metribuzin’s detrimental effects, underscoring the potential of employing microbial strategies for managing pesticide stress in wheat cultivation.
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