Screening High-Biomass Grasses for Cadmium Phytoremediation

Abstract

Investigating the ability of non-hyperaccumulator plants to grow in soils polluted by cadmium (Cd) and their potential for phytostabilization or phytoextraction is essential for assessing their use in phytomanagement efficiency. Therefore, we evaluated the tolerance of high-biomass grasses to Cd by measuring biomass production and element accumulation and valued them for their suitability for phytoextraction or phytostabilization purposes on moderately Cd-polluted land (total Cd concentration of 7.5 mg kg(-1)) by determining Cd accumulation in the plants and calculating the bioconcentration (Cd BCF) and translocation factors (Cd TF). Among the ten species under investigation, Panicum maximum cv. Massai and Pennisetum glaucum cv. Purpureum Schum showed lower root biomass due to Cd exposure. Cadmium exposure altered element accumulation in some grass species by reducing P, K, and Mg accumulation in P. glaucum cv. Purpureum Schum; K accumulation in P. maximum cv. Massai; Mg accumulation in P. maximum cv. Momba & ccedil;a; Ca, Fe, and Zn accumulation in P. maximum cv. Aruana; and B accumulation in Brachiaria brizantha cv. Piat & atilde;. However, this was not correlated with lowered biomass production, except for K, which was associated with lowered root biomass allocation in P. maximum cv. Massai and P. glaucum cv. Purpureum Schum. Cadmium concentrations decreased from roots to shoots, indicating a clear limitation of upward Cd transport. Although some grasses exhibited a Cd BCF > 1, the Cd TF remained below 0.4 for all tested species. These results indicate that, under moderate Cd pollution, the evaluated grasses are more suitable for Cd phytostabilization than phytoextraction, except for P. maximum cv. Massai and P. glaucum cv. Purpureum Schum, which showed inhibited root growth and may not be efficient over time.