β-sulfur-engineered biochar mitigates scandium toxicity in wheat: Impacts on growth characteristics, photosynthetic activity, and redox regulation

Scandium (Sc) is acknowledged as a toxic substance that negatively impacts crop growth and physiological and biochemical metabolism. The main purpose of the present research was to examine the influence of β-Sulfur-engineered rice husk biochar (βS-MBC) in comparison to pristine biochar (PBC) on wheat under scandium exposure (40 mg L−1). Results indicated that scandium toxicity markedly inhibited wheat seedling growth, as revealed by decreases in fresh weight of shoot, chlorophyll pigments concentration, photosynthesis rate, also root characteristics; with greater scandium build-up was noted in roots and shoot of scandium-stressed samples relative to PBC and βS-MBC-treated plants. The βS-MBC treatment promoted wheat growth more efficiently than PBC, with increments of shoot fresh weight (59.39 %), root length (59 %), Chl-a (49.30 %), Chl-b (48.31 %) and carotenoids (51.19 %), as well as improved gas exchange characteristics. βS-MBC decreased scandium deposition by in leaves (-37.10 %) and roots (-25.11 %) relative to scandium-stressed plants. βS-MBC enhanced scandium stress resistance in wheat by increasing activities of antioxidant enzyme in root and leaf, such as CAT (99.89 %/120.12 %), Gr (59.43 %/199.19 %), SOD (91.39 %/86.31 %), GST (120.81 %/131.69 %), GPX (81.91 %/84.19 %), MDHAR (91.11 %/86.38 %), DHAR (63.11 %/54.59 %) and APX (64.69 %/90.31 %), while concurrently diminishing H2O2 (by 20.10 %/17.61 %) and MDA (18.59 %/13.80 %). Moreover, βS-MBC augmented activity of Gly-I (80.09 %/100.20 %) and Gly-II (100.30 %/120.33 %), alleviating methylglyoxal-caused toxicity, and elevated antioxidant-glyoxalase systems and metal-resistant gene expression (OsFSD-1). The βS-MBC treatment showed greater efficacy than PBC in mitigating scandium-induced toxicity and enhancing wheat growth. Nevertheless, additional research is required to ascertain precise driving mechanisms involved in growth promotion.