Intercropping and exogenous calcium oxide nanoparticles mitigate cadmium toxicity in faba bean

Background and aims Trace element contamination, like cadmium (Cd), threatens agriculture and health. This study assessed Cd stress effects on photosynthesis in faba bean and evaluated mitigation using intercropping with wheat and calcium oxide nanoparticles (CaO NPs). Methods Five treatment groups were established: faba bean monoculture without Cd addition (M), monoculture with Cd addition (M + Cd), monoculture with both Cd and CaO NPs (M + Cd + CaO NPs), wheat-faba bean intercropping with Cd addition (I + Cd), and intercropping with both Cd and CaO NPs (I + Cd + CaO NPs). Results Compared with M, the M + Cd treatment significantly suppressed faba bean growth by 34.1–102.9%, decreased the mineral nutrient content by 90.0–142.7%, reduced the photosynthetic pigments by 136.5–207.1%, lowered the photosynthetic rate by 60.0–198.5%, diminished the electron transfer efficiency by 19.8–117.8%, and decreased the photosynthetically assimilated substances by 70.8–123.2%. Severe damage to chloroplast structure was also observed. Compared with the M + Cd treatment, the I + Cd + CaO NPs treatment significantly alleviated these inhibitory effects. It restored damaged chloroplast structures, increased photosynthetic pigment content by 76.0–144.0%, enhanced photosynthetic rates by 14.5–71.1%, improved electron transport efficiency by 14.5–71.1%, and reduced Cd accumulation in stems and roots by 66.1–131.9%. Conclusion The integration of intercropping and CaO NPs application enhanced photosynthetic performance and plant growth in faba bean, thereby reducing the toxic impact of Cd stress. Graphical The alternative text for this image may have been generated using AI.