Co-application of iron modified biochar and metal resistant bacteria alleviates antimony toxicity in rice by modulating morpho-physiological and biochemical traits and soil microbial activities

Antimony (Sb) pollution is becoming more prevalent due to human activities. Recently, biochar (BC) and modified biochar have been used to remediate polluted soils. Nevertheless, role of modified BC and microbes to mitigate adversities of Sb is not understood. This study evaluated the effects of iron-modified biochar (FMB) and bacteria ( Ochrobactrum oryzae ) on rice plant functioning, Sb bio-accessibility, and microbial community structure and diversity. The experiment consisted of different treatments; control, Sb stress (1200 mg kg −1 ), Sb stress (1200 mg kg −1 ) + FMB (2.5 %), Sb stress (1200 mg kg −1 ) + bacterial inoculation and Sb stress (1200 mg kg −1 ) + FMB (2.5 %) + bacterial inoculation. The combined FMB and bacteria increased photosynthetic pigments, antioxidant activities, osmolyte accumulation and reduced oxidative damage, electrolyte leakage (EL), and malondialdehyde (MDA), thereby leading to better growth and yield. Combined FMB and bacterial inoculation also enhanced soil nutrient availability, soil organic carbon (SOC), and soil enzymatic activities thereby reducing the soil antimony availability (46.12 %) and bio-accessibility of Sb (Sb-bio: 59.25 %). Moreover, co-applying BC and bacteria inoculation reduced Sb accumulation rice roots and grains which was associated with increased soil pH, SOC, and soil enzyme activity. Additionally, FMB and bacteria application increased the abundance of favorable bacteria including Proteobacteria , Gemmatimonadete, Firmicutes , Bacteroidota , Chloroflexi , Myxococcota and Parcubacteria which also helped to counteract the toxic impacts of Sb. Therefore, the combination of FMB and bacteria can increase rice production in Sb-polluted soils. These findings offer a way to develop environmentally friendly technologies to improve safer and sustainable rice production in Sb-contaminated soils. • Antimony caused a serious reduction in growth by increasing oxidative damage. • Biochar and bacteria enhanced antioxidant activities, and osmolyte synthesis. • Co-applied biochar and bacteria improved soil properties and reduced Sb bio-accessibility. • Biochar and bacteria partnership enhanced the abundance and diversity of beneficial bacteria.