Arundo donax L. stress tolerance under irrigation with heavy metal aqueous solutions

This study investigates the influence of widely ranged soil cadmium and nickel content on the biomass quantity and quality produced by Arundo donax L. (giant reed). The aim was to determine whether giant reed is hypertolerant to these heavy metals and therefore could exploit polluted sites, which could not be used for food production, by producing useful biofuel. A 2-year pot experiment was held in the field and an automated drip irrigation system was established to provide daily the plants with aqueous solutions of cadmium and nickel in concentrations of 5, 50 and 100 mg l−1, against the control (tap water). At the end of each experimental year the soil total Cd and Ni content was determined and ranged between 13.5 mg kg−1 Cd and 68.5 mg kg−1 Ni (low treatment — first year) and 973.8 mg kg−1 Cd and 2543.3 mg kg−1 Ni (high treatment — second year). During both growing periods the number of branches was recorded. In mid October of each year the plants were harvested and the plant height and the fresh and dry weight of stems, leaves, branches, root system, above ground part and total plant were determined. Also, giant reeds biomass allocation, moisture content (%) and water use efficiency were measured. The observed morphological and biomass characteristics were smaller than those reported in literature due to the fact that the plants were grown in pots. Nevertheless, all measured parameters did not differ among treated and control plants, indicating the high tolerance ability of that species to the examined metals.