Morpho-physiological traits, antioxidant capacity and phytoextraction of copper by ramie ( Boehmeria nivea L.) grown as fodder in copper-contaminated soil

Abstract

Ramie (Boehmeria nivea L.), the oldest fiber crop in China, can also be grown as fodder crop because of its huge biomass production. Moreover, it has the potential to colonize heavy metal–contaminated soils which showed the possibilities of phytoremediation using B. nivea. Therefore, the present study was conducted to investigate the potential of B. nivea for phytoextraction of copper (Cu)-contaminated soil. Moreover, the impact of different concentrations of Cu on growth and antioxidant enzymatic activity by B. nivea were also studied. For this purpose, a pot experiment was conducted to examine the growth, antioxidative response, and localization (distribution) of Cu in B. nivea plant under different Cu concentrations (0, 50, 100, 200, 300, and 400 mg kg⁻¹ soil). Results revealed that B. nivea tolerated up to 100 mg kg⁻¹ Cu concentration without a significant decrease in biomass, but further increase in Cu concentration from 200 to 400 mg kg⁻¹ exhibited a significant reduction in chlorophyll content, fresh and dry biomass, plant height, and number of leaves. It was further observed that B. nivea accumulated more Cu in roots (26 to 53 mg kg⁻¹), followed by the leaves (23 to 28 mg kg⁻¹) and stems (14 to 21 mg kg⁻¹), while the values for both bioaccumulation factor (BAF) and translocation factor (TF) at all treatments were less than 1. Moreover, activities of antioxidative enzymes (superoxide dismutase and peroxidase) were initially increased with the exposure of 50, 100, and 200 mg kg⁻¹ Cu, but decreased by further increasing the Cu concentration to 300 and 400 mg kg⁻¹ indicating the oxidative stress which is manifested by high malondialdehyde (MDA) and proline contents also. Thus, based on results, it can be concluded that B. nivea accumulated relatively low Cu contents in aboveground parts and could be grown as fodder crop for phytoremediation of Cu-contaminated sites.

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