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 (Sb) toxicity is a significant threat to crop production and humans. Its concentration is increasing in soil and water due to human activities which needs dire attention to address this challenge. Biochar is a promising amendment to remediate polluted soils, however, its role in mitigating the toxic impacts of Sb on plants is still unclear. Seaweed-based fertilizer (SBF) has shown appreciable results in improving plant performance, however, its role against metal/metalloids toxicity has not been studied yet. Therefore, this study tested the impacts of BC and SBF in mitigating the harmful effects of Sb on rice. The study was carried out with the following treatments; control, Sb stress (600 mg kg(-1)), Sb stress + biochar (2%), Sb stress + seaweed-based fertilizer (SBF: 2%), and Sb stress + BC (1%) and SBF (1%). The results showed that Sb toxicity adversely affected rice growth and productivity by impeding photosynthetic pigments, leaf relative water contents, increasing production of oxidative stress biomarkers (electrolyte leakage: EL, hydrogen peroxide: H2O2, malondialdehyde: MDA), and accumulation of Sb in plant parts. Contrarily, BC and SBF blends mitigated Sb-induced growth and yield damages in rice by improving photosynthetic efficiency, osmolyte synthesis, nutrient uptake, soil enzymatic activity, and antioxidant activities. Moreover, BC and SBF blend also reduced the bio-accessible Sb concentration (95.63%), bio-accessibility of Sb (25.40%), Sb transport coefficient (35.70%) and soil Sb antimony concentration (52.74%). Given these findings, the co-application of BC and SBF showed a profound improvement in rice yield by regulating photosynthetic performance, antioxidant activities, oxidative stress markers, antioxidant activities, and soil properties.