Cadmium (Cd) contamination in soil adversely affects crop productivity, grain quality, and human health. Applications of boron (B) and biochar are known to impart tolerance to crops against abiotic stresses. A pot experiment was performed to assess the effects of the sole and combined application of B and biochar on growth, physiological and antioxidant defense mechanisms, yield, and grain quality of wheat under Cd toxicity-induced stress. The treatments included control (0 mg kg⁻¹ and 0 g kg⁻¹), only Cd (15 mg kg⁻¹), only B (5 g kg⁻¹), only biochar (50 g kg⁻¹), B plus biochar, Cd plus B, Cd plus biochar, and Cd plus B plus biochar, which were applied at the time of sowing and were arranged using completely randomized design (CRD) with five replications. The individual Cd toxicity (15 mg kg⁻¹) significantly reduced chl a, chl b, and chl a+b, as well as primary metabolites (soluble protein, amino acids, total soluble sugar, and phenolic contents), while it increased the activities of enzymatic antioxidants like superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) in the leaves of wheat. In addition, Cd stress (15 mg kg⁻¹) increased lipid peroxidation in the form of malondialdehyde (MDA), and it enhanced the hydrogen peroxide (H₂O₂) content, electrolyte leakage (EL), and proline contents in the leaves. Furthermore, Cd (15 mg kg⁻¹) contamination reduced the grain yield and yield-related attributes relative to respective no-Cd treatments. Soil-applied B and biochar improved wheat grain yield by triggering the activities of enzymatic antioxidants. Individual or combined B and biochar applications improved proline contents and reduced H₂O₂ and MDA contents in plants. The combined application of B and biochar enhanced soluble sugars and total phenolic as compared to the control and Cd-contaminated plants. In conclusion, the combined application of B and biochar was found to be the best soil amendment strategy to improve the yield of wheat under Cd-contaminated soil.

A combination of mineral nutrients and plant growth regulators should be assessed to improve crop performance under various abiotic stresses. There is a need to include plant growth regulators in fertilization regime of various crops along with essential mineral nutrients, especially when they are irrigated with polluted water with higher levels of heavy metals. The performance of pea was evaluated under cadmium (Cd) stress coupled with potassium (K) and jasmonic acid (JA) supplementation. The Cd stress (50 μM) was applied to soil (sandy loam) grown pea plants as basal dose after a month of sowing. The control and stressed plants were then supplemented with K (5 M), JA (0.5 mM) and their collective application along with control as distilled water. Cd stress showed a marked reduction in growth pattern, however, the collective supplementation sufficiently improved the growth pattern of stressed peas plants as evidenced by improvement in shoot length (cm), root length (cm), number of leaves per plant, leaf area (cm²), plant fresh and dry weight (gm). Potassium application under Cd stress significantly enhanced internodal distance (cm) while the number of seeds per pod and relative water contents remained nonsignificant. The applied treatment (JA + K) under Cd stress prominently improved enzymatic activities, which were measured as nitrate reductase activity (NRA), nitrite reductase activity (NiRA), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT). Cd stress impacted the biochemical profile by enhancing antioxidant capacity (AC), antioxidant activity (AA), total phenols (TP), while reducing total soluble protein (TSP), chlorophyll ‘a’, chlorophyll ‘b’ and carotenoids. The combined application of JA and K under Cd stress enhanced AC, AA, TP, Chl a and b, TSP and carotenoids. The results indicate that foliar application of JA and K efficiently negated the harmful effects of Cd stress on peas.

Cadmium (Cd) toxicity is a serious threat to agronomic crop productivity worldwide. It raises severe concerns about the food and nutrient security required to meet the demands of a rapidly growing population, while also creating grave challenges for agriculture. Silicon (Si) and strigolecton (SL) are reported to impart multiple benefits to plants exposed to abiotic stress. Therefore, the current experiment was performed to evaluate the effects of silicon (4.0 mM) and strigolecton (20 µM) on the amelioration of cadmium (25 mg kg⁻¹ soil) stress in maize seedlings via intervention in morphological attributes, photosynthetic pigments, enzymatic antioxidant mechanisms, and osmolyte accumulation. The results indicated that morphological attributes and photosynthetic pigments were significantly reduced in Cd-exposed seedlings. However, foliar application of Si and SL, both individually and in combination, significantly improved the growth attributes and photosynthetic pigments of maize seedlings under both control and Cd-stress conditions. Exposure of maize seedlings to Cd stress increased H₂O₂ levels, malondialdehyde content, and electrolyte leakage and reduced cell membrane stability. These effects were significantly negated by Si and SL supplementation, both individually and in combination. Moreover, enzymatic antioxidants, including catalase, superoxide dismutase, peroxidase, and ascorbate peroxidase, were activated after Cd stress, but their activity was further increased with foliar application of Si or SL. In Cd-contaminated seedlings, the combined application of Si and SL enhanced soluble proline, sugars, and total phenolic contents as compared to the control treatment. Furthermore, Si and SL applications increased Si accumulation in Cd-exposed seedlings and decreased Cd uptake. It was concluded that the combined application of Si and SL improved Cd tolerance in maize seedlings by modulating morpho-physiological attributes, photosynthetic pigments, and osmolytes accumulation, and by supporting the antioxidant defense system. The findings of this study suggest that Si and SL could be safe and effective strategies for reducing Cd toxicity in maize seedlings.