Effect of different copper levels on growth and morpho-physiological parameters in giant reed (Arundo donax L.) in semi-hydroponic mesocosm experiment

In Mediterranean countries, the use of copper-based fungicides in agriculture is causing a concerning accumulation of copper in the upper layer (0-20 cm) of soils and water bodies. Phytoremediation by energy crops offers the chance to associate the recovering of polluted environments with the production of biomass for bioenergy purposes. The purpose of this work was to evaluate the morpho-physiological response of giant reed (Arundo donax L.), a well-known energy crop, when treated with increasing concentrations of Cu (0, 150, and 300 ppm) in a semi-hydroponic growing system (mesocosm) for one month. The plant morphology (height and base diameter of the stem, number of stems) was not affected by the treatments. The presence of Cu led to the disequilibrium of Fe and Zn foliar concentration and caused an impairment of photosynthetic parameters: at 150 and 300 ppm the chlorophyll content and the ETR were significantly lower than the control. The study demonstrated that, although the presence of Cu may initially affect the plant physiology, the Arundo plants can tolerate up to 300 ppm of Cu without any adverse effect on biomass production, even when grown in semi-hydroponic conditions.