Mixed Pb and Cd soil contamination is an issue in Northeast China. We examined the effects of exogenous organic acids on the resilience of Changbai larch (Larix olgensis) seedlings, a pioneering forestry species in afforestation and vegetation restoration in Northeast China, under such stress. Mixed Pb and Cd stress led to significantly higher Pb and Cd content in the leaves and fine roots, malondialdehyde content in the leaves, superoxide dismutase activity, and soluble protein content in the leaves. Lower biomass of the roots, stems, and leaves was observed, with the roots showing the sharpest reduction in biomass. However, the application of organic acids mitigated or reversed these effects. This was most pronounced following treatment with 0.2 mmol·L-1 or 1.0 mmol·L-1 organic acids for 20 days. Citric acid had the greatest positive effect compared with succinic acid and oxalic acid. We suggest that exogenous organic acids have the potential to alleviate Pb and Cd-induced oxidation injury symptoms in Changbai larch seedlings, and may enhance resilience to mixed Pb and Cd stress.
Keywords: Changbai larch seedlings; ecological resistance to mixed pb and cd stress; exogenous organic acids.