The Suitability of Several Grasses for the Remediation of Hotspots Affected by Cadmium Contamination

Abstract

Areas contaminated with cadmium require remediation because it is a highly toxic element. The aim of this study was to assess the Cd tolerance of four grass species (Poa pratensis, Lolium perenne, Festuca rubra, and Festuca pratensis) and to identify the most useful grass for the phytostabilization of areas with extremely high Cd content in the soil. Additionally, the relationship between grass tolerance to Cd and the glutathione (GSH) content in shoots was examined. Two series of pot experiments were carried out using soil artificially contaminated with Cd. Three levels of contamination were used—30, 60, and 130 mg kg−1 Cd—against a control. The plants were cut down 2 months after sowing. At the Cd1 level, L. perenne showed the highest tolerance to Cd (tolerance index TI = 86), while P. pratensis had the lowest tolerance (TI = 65). At Cd2, the TIs ranged from 52 to 59, indicating a similar tolerance of all species. Cd3 was most harmful to L. perenne (TI = 24), while P. pratensis was the most tolerant (TI = 31). Grassroots accumulated much more Cd than shoots. L. perenne showed the greatest increase in root Cd at each contamination level, followed by F. pratensis and then P. pratensis and F. rubra. It is noteworthy that the tolerance of grasses to Cd3 was related to the GSH content in shoots. P. pratensis and F. rubra increased the GSH content 4.6 and 3.6 times, respectively, while L. perenne and F. pratensis only increased it 2.3 times compared to the control plants.