Biomass accumulation and heavy metal uptake of giant reed on polluted soil in southern Italy.

Giant Reed (Arundo donax L.) is well known for its adaptability to different ecological conditions, growing spontaneously in different regions of Southern Europe. Due to its high biomass productivity, it is commonly used for the production of energy, paper pulp, and wooden building materials (Papazoglou et al., 2005). Giant Reed could also be a useful tool for soil bioremediation thanks to its high resistance to pollutants (Papazoglou, 2006) together with a high accumulation capability of heavy metals in plant tissues (especially in rhizomes). A field trial was established in Acerra (Southern Italy, Campania) to asses the potential productivity of Giant Reed on a soil with high concentration of heavy metals. Treatments resulted from a factorial combination of two levels of compost (treated and non treated soil) and Trichoderma (inoculated and non inoculated rhizome). Soil samples were collected at twodepths (0-20 and 20-40 cm)at transplanting and at harvest. Soil and rhizosphere samples from plots under the different treatments were sampled and the composition of total aerobic bacteria, fungi, actinobacteria and microbial groups involved in key processes of the nitrogen cycle (e.g. aerobic free-living N2-fixing bacteria and ammonia-oxidizing bacteria) was estimated and the structure of cultivable populations was assessed. Plant aboveground tissues and rhizomes were collected after one growing season. A two-way ANOVA was performed on data considering compost addiction as main factor and Trichoderma inoculation as sub-factor in a split-plot design. Means were separated by LSD test according to a p-value of 0.05. Compost addiction allowed highest biomass production (13.2 Mg ha-1 vs 11.9 Mg ha-1 DMof non fertilized plots) and consequently highest metal uptakes. No interaction between factors was found. These results show the possibility of use Giant Reed for energy production on contaminated soils allowing incomes to farmers and reducing the levels of contamination.