[Responsive Characteristics of Symphytum officinale L. to Pb， Zn， and Cd Heavy Metals Under Hydroponic Conditions].

In the context of the increasingly serious soil heavy metal pollution， delving deeply into the response mechanisms of plants to heavy metals and their remediation potential is of great significance for the restoration of the ecological environment. This study investigated Symphytum officinale L. via hydroponic pot experiments under single and combined stresses of lead （Pb）， zinc （Zn）， and cadmium （Cd） with different concentration gradients. Through a systematic analysis of growth indicators， antioxidant enzyme activities （superoxide dismutase [SOD]， catalase [CAT]， peroxidase [POD]）， malondialdehyde （MDA） and proline （Pro） contents， as well as heavy metal accumulation patterns， we comprehensively clarified the stress response and accumulation characteristics of comfrey under heavy metal exposure. The results demonstrated that heavy metal stress exerts a significant influence on the growth of Symphytum officinale L.. Its biomass， leaf length， leaf width， and stem length are negatively correlated with the stress concentration， and the inhibitory effect of combined stress is more pronounced. Nevertheless， Symphytum officinale L. shows good tolerance to both single and combined stresses. Only the degree of root inhibition varies according to the type and concentration of heavy metals. At the physiological and biochemical levels， heavy metal stress inhibits the synthesis of chlorophyll and has complex effects on the activities of antioxidant enzymes such as SOD， POD， and CAT， as well as the contents of MDA and Pro. Compared with single stress， combined stress generally has a more intense inhibitory effect on enzyme activities. Under different heavy-metal stresses， each indicator presents different changing trends. Regarding accumulation capacity， the absorption and enrichment amounts of Pb， Zn， and Cd by Symphytum officinale L. increase significantly with the increase of stress concentration. The enrichment amount in roots is significantly higher than that in the aboveground counterparts， and the enrichment ability under single stress is stronger than that under combined stress. Although its transfer effect on heavy metals is not ideal， its enrichment ability far exceeds that of common plants. It has certain tolerance and detoxification abilities and is an excellent germplasm resource for remediating heavy - metal - polluted soil. This study provides crucial support for the application of Symphytum officinale L. in the remediation of polluted soil and the research on related mechanisms.