Integrative approach to mitigate chromium toxicity in soil and enhance antioxidant activities in rice (Oryza sativa L.) using magnesium–iron nanocomposite and Staphylococcus aureus strains

Pollutants in soil, particularly chromium (Cr), pose high environmental and health risks due to their persistence, bioavailability, and potential for causing toxicity. Cr impairment in plants act as a deleterious environmental pollutant that enters the food chain and eventually disturbs human health. Current study demonstrated the potential of integrative foliar application of magnesium–iron (Mg + Fe) nanocomposite with Staphylococcus aureus strains to alleviate Cr toxicity in rice (Oryza sativa) crops by improving yield and defense system. Growth and yield traits such as shoot length (15%), root length (17%), shoot fresh weight (14%), shoot dry weight (9%), root fresh weight (23%), root dry weight (7%), number of tillers (33%), number of grains (10%) and spike length (13%) improved by combined application of Mg + Fe (20 mg L⁻¹) nanocomposite and S. aureus strains with Cr (110 mg kg⁻¹), compared to when applied alone. Mutual Mg + Fe and S. aureus strains application augmented the SPAD value (9%), total chlorophyll (11%), a (12%), b (17%), and carotenoids (32%), with Cr (110 mg kg⁻¹), compared to alone. Malondialdehyde (13%), hydrogen peroxide (H₂O₂) (11%), and electrolyte leakage (7%) were significantly regulated in shoots with combined Mg + Fe and S. aureus strains application with Cr (110 mg kg⁻¹) contrasted to alone. Peroxidase (20%), superoxide dismutase (17%), ascorbate peroxidase (18%), and catalase (20%) were increased in shoots with combined Mg + Fe and S. aureus strains application with Cr (110 mg kg⁻¹) in comparison to alone. The combined application of Mg + Fe (20 mgL⁻¹) nanocomposite and S. aureus strains with Cr (110 mg kg⁻¹) enhanced the macro-micronutrients in shoots compared to alone. Cr accumulation in roots (21%), shoots (25%), and grains (47%) were significantly reduced under Cr (110 mg kg⁻¹) with combined Mg + Fe and S. aureus strains application, compared to alone. Subsequently, applying combined Mg + Fe and S. aureus strains is a sustainable solution to boost crop production under Cr toxicity.