Evaluation Of The Phytostabilization Potential Of Phalaris Arundinacea L. For Cadmium And Copper Contaminated Soil In Arid And Semi Arid Areas

As a result of the increased utilization of mineral resources as well as the increased scarcity of water resources, heavy metal stress and is widely increasing in both arid and semi-arid regions. Phytoremediation technology can be used to repair of heavy metals in arid and semi arid regions. The one of success of phytoremediation depends on the choice of appropriate plant species.To evaluate the phytoremediation potential of reed canary grass(Phalaris arundinacea L.), biomass, relative conductivity, MDA, proline content, chlorophyll content, photosynthetic characteristics, and translation factors of mineral elements as well as Cd and Cu accumulation characteristic were studied using an orthogonal experimental design with three factors(i.e., cadmium(Cd), copper(Cu), and soil moistures) and three levels(i.e., Cd at 50, 110, 170 mg/kg, Cu at 100, 275, 450 mg/kg, and soil moistures at 20%, 50%, 80%) of each factor in pot experiments in greenhouse.We found that:1)At a soil moisture of 20%, biomass and chlorophyll content at this soil moisture level was the lowest of all conditions while the contents of relative conductivity, MDA and proline were significantly increased. However, there was no significant or relatively small difference between all other treatments and the control group. The results showed that reed canary grass has certain resistance to heavy metal and drought stress.2) The accumulation of cadmium and copper in roots was higher than in shoots.The bioaccumulation factors of cadmium and copper were both higher than one, with the bioaccumulation factor of cadmium being greater than that of copper, which suggestedreed canary grassis suitable forphytostabilization.The translocation factors of cadmium and copper were both lower than one.3) At a soil moisture of 20%, photosynthetic characteristics(net photosynthetic rate,Intercellular CO2 concentration, stomatal conductance and transpiration rate) at this soil moisture level was the lowest of all conditions. There was no significant or relatively small difference between all other treatments and the control group. The results showed that reed canary grass has a high resistance to water stress and heavy metal.4) At a soil moisture of 20%, The translation factors of K, Ca, Mg and Mn at this soil moisture level were significantly decreased while the translation factors of Zn and Fe were significantly increased, compared with the control group. However, there was no significant or relatively small difference between all other treatments and the control group. It suggested that moderate drought stress and heavy metal have little impact on the translation factors of the mineral elements.5)The effect of water stress on biomass, physiological index, photosynthetic, translocation factors of mineral nutrition, and shoot cadmium and copper andtranslocation factorsis much more significant than heavy metal stress, meanwhile, it is just opposite regarding to root cadmium and copper and bioaccumulation factors.6) Biomass of reed canary grass presented significantly positive correlation with photosynthetic parameters, chlorophyll content and translocation of Ca, Mg, K, Mn, while it showed a highly significant negative correlation with the relative conductivity, MDA, proline and shoot Cd and Cu.In conclusion, we suggested that Phalaris arundinacea L. is a promising candidate for phytostabilization Cd and Cu contaminated soil in moderate drought areas to prevent the diffusion of metal ions and reduce the toxic effects on the environment. Furthermore, it is more suitable for the phytostabilization of Cd contaminated soil than that of Cu.