Intercropping with Bidens pilosa can effectively reduce Cd absorption and improve tobacco leaf quality

To explore the feasibility of intercropping super-enriched plants with tobacco (Nicotiana tabacum) to mitigate heavy metal uptake in tobacco and enhance leaf quality, we conducted an indoor sand cultivation experiment. This experiment examines differences in growth, cadmium (Cd) uptake, and chemical composition of tobacco leaves when intercropped with Bidens pilosa under various levels of Cd stress. Our two-factor design includes Cd treatments and intercropping. The Cd treatments comprise a control (CK, no added Cd) and Cd10 (Cd concentration of 10 mg/L), each with three planting types: monocultures of B. pilosa, monocultures of tobacco, and intercropping of B. pilosa/tobacco. Our results demonstrate that intercropping significantly boosts tobacco photosynthesis under no Cd treatment, with transpiration rate (Tr) and stomatal conductance (Gsw) increasing by 54.91% and 54.55%, respectively. Under Cd stress, intercropping elevates the chlorophyll fluorescence parameters in both plants, enhancing stress tolerance. Notably, intercropping substantially increases the Cd concentration in B. pilosa tissues (with stem Cd concentration rising by 128.81%) and concurrently reduces Cd concentration and accumulation in tobacco tissues. Specifically, stem and leaf Cd concentrations in tobacco decrease by 60.72% and 83.46%, respectively, and shoot Cd accumulation drops by 71.59%. Additionally, intercropping alters the content of chemical components in tobacco leaves, skewing them toward more optimal levels. Therefore, B. pilosa/tobacco intercropping markedly impedes the uptake and accumulation of Cd in tobacco, simultaneously improving leaf quality. These findings offer a reference for safe, high-quality tobacco production.