Growth responses and accumulation of cadmium in switchgrass (Panicumvirgatum L.) and prairie cordgrass (Spartinapectinata Link)

Abstract

Phytoextraction could be an efficient technique to remediate heavy metals from contaminated soils. Identifying bioenergy crops that can be produced successfully on marginal lands, such as those polluted by heavy metals, also reduces the pressure to produce energy crops on land that would otherwise be used to produce food crops. The objective of this study was to determine the phytoremediation capability of two warm season perennials, prairie cordgrass (Spartinapectinata Link, ‘Savoy’) and switchgrass (Panicumvirgatum L., ‘Cave-In-Rock’ (CIR)) through their growth response to cadmium (Cd). Growth rate, Cd tolerance, accumulation and translocation were measured at concentrations of 0 (control), 5, 10, 30, and 50 mg L⁻¹ of Cd mixed with Hoagland's solution in an aerated hydroponic system. Although a reduction of plant growth was observed when the Cd concentration was higher than 10 mg L⁻¹ for both species, there were significant differences in Cd tolerance, translocation and accumulation between species. The tolerance index (T_i) was between 72.5 and 107.1 in Savoy and 48.7 and 75.7 in CIR under Cd concentrations of 50 mg L⁻¹ and 5 mg L⁻¹, respectively. The translocation factor (T_f) for both species was increased with increasing Cd concentration in solution, but the T_f of Savoy was higher than CIR. The highest bio-concentration factor (BCF) of the roots reached 325.7 for Savoy and 144.5 for CIR when the Cd concentration was 5 mg L⁻¹ and the BCF of the shoots in both species was consistently low (13.7 to 16.8 and 4.1 to 6.0 for Savoy and CIR, respectively) indicating higher Cd retention in the roots than shoots. It was concluded that both species could be utilized in phytoremediation when the Cd concentration is less than 10 mg L⁻¹, however Savoy has the higher tolerance, translocation and accumulation capabilities which makes it a better candidate for phytoremediation and biomass production on Cd polluted soils.