This study evaluated the phytotoxicity and germination responses of four plant species, Neltuma glandulosa, Parkinsonia aculeata, Leucaena leucocephala, and Albizia lebbeck, in soils collected from Lake Junín, Peru. Soil samples were obtained using a composite sampling approach from contaminated sites and characterized for texture, organic matter, pH, electrical conductivity, and potentially toxic elements (PTEs). The experiment was conducted under controlled laboratory conditions using a completely randomized design with four replicates per treatment. Germination responses were assessed through germination percentage, germination index (IG), mean germination time, and radicle elongation. Data were analyzed using multivariate analysis of variance and principal component analysis to evaluate species-specific responses and relationships with soil properties.

Soil characterization revealed a sandy clay loam texture with low organic matter content (1.1% ± 0.07). The soil from Site 2 (T2) exhibited the highest toxicity, linked to elevated concentrations of PTEs, increased pH and EC, and lower adsorption capacity due to soil texture and organic matter content. Phytotoxicity was assessed using the IG: values above 80% indicated low phytotoxicity, 50–80% moderate, and below 50% severe toxicity. N. glandulosa and P. aculeata showed greater tolerance, whereas L. leucocephala and A. lebbeck were more susceptible. Germination percentage was generally not severely impacted by PTEs, often remaining above 75%, but radicle elongation was more sensitive, showing clear inhibitory effects.

These results highlight the complex interactions between soil physical-chemical properties and toxic element bioavailability that regulate germination success. Species native to the Lake Junín area (N. glandulosa and P. aculeata) demonstrated greater tolerance, while exotic species such as A. lebbeck were more susceptible to phytotoxic effects. This work provides valuable insights for ecological risk assessment and revegetation strategies in contaminated Andean soils under similar environmental conditions.