Potential for phytoextraction of copper by Sinapis alba and Festuca rubra cv. Merlin grown hydroponically and in vineyard soils

The extensive use of copper-bearing fungicides in vineyards is responsible for the accumulation of copper (Cu) in soils. Grass species able to accumulate Cu could be cultivated in the vineyard inter-rows for copper phytoextraction. In this study, the capacity of Festuca rubra cv Merlin and Sinapis alba to tolerate and accumulate copper (Cu) was first investigated in a hydroponic system without the interference of soil chemical-physical properties. After the amendment of Cu (5 or 10 mg Cu l-1) to nutrient solution, shoot Cu concentration in F. rubra increased up to 108.63 mg Cu kg-1 DW, more than three times higher than in S. alba (31.56 mg Cu kg-1 DW). The relationship between Cu concentration in plants and external Cu was dose-dependent and species specific. Results obtained from the hydroponic experiment were confirmed by growing plants in pots containing soil collected from six Italian vineyards. The content of soil organic matter was crucial to enhance Cu tolerance and accumulation in the shoot tissues of both plant species. Although S. alba produced more biomass than F. rubra in most soils, F. rubra accumulated significantly more Cu (up to 3-4 fold) in the shoots. Given these results, we recommended that F. rubra cv Merlin could be cultivated in the vineyard rows to reduce excess Cu in vineyard soils.