Potential phytoremediation of Pampa biome native and invasive grass species cohabiting vineyards contaminated with Cu in Southern Brazil

Abstract

The aims of the present study are to evaluate whether the growth of Pampa biome native grass species Axonopus a nis, Paspalum notatum and Paspalum plicatulum, as well as of invasive grass species Cynodon dactylon, is compromised by excessive Cu availability in the soil (0, 35 and 70 mg of Cu kg -1 ), to determine the impact of excessive Cu on the physiological responses of the investigated species and to assess whether these species have the potential to enable the phytoremediation of soils contaminated with Cu. C. dactylon presented the best performance in soil contaminated with 35 mg of Cu kg -1 . In C. dactylon, the concentrations of chlorophyll b and carotenoids increased, as did the photosynthetic rate and plant growth. Phytotoxic effects of Cu in soil contaminated with 70 mg of Cu kg -1 were more severe on A. a nis and led to plant death. The other species presented reduced photosynthetic and growth rates, as well as increased activity of antioxidant enzymes such as SOD and POD. This very same Cu level has decreased photosynthetic pigment concentrations in P. notatum and P. plicatulum. On the other hand, it did not change chlorophyll a and b concentrations in C. dactylon and increased carotenoid concentrations in it. High values recorded for Cu bioaccumulation-in-grass-root factor, mainly in P. plicatulum, have indicated that the investigated plants are potential phytostabilizers. High C. dactylon biomass production -in comparison to other species -compensates for the relatively low metal concentration in its tissues by increasing metal extraction from the soil. This makes C. dactylon more e cient in the phytoremediation process than other species.