The Study Of The Remediation Charecteristics Of Pennisetum Sp In Cd Contaminated Soil

Pennisetum sp which has large biomass and strong stress resistence, is a perennial energy grass which introducted and cultivated extensively. In order to study the effect of Cd stress on growth characteristics and Cd accumulation of Pennisetum sp in three typical soil types of Sichuan (alluvial soil, purple soil and yellow soil), a pot experiment was conducted with four levels of Cd treatment (0 mg/kg; 20 mg/kg; 50 mg/kg; 100 mg/kg). The results were as followed:1) Within the range of Cd concentration in our experiment, higher Cd concentration (50 mg/kg,100 mg/kg) influenced the growth of Pennisetum sp significantly, but low Cd concentration (20 mg/kg) had no significant effects. The height, organ biomass and total biomass decreased with the increased of Cd concentration and showed an order of alluvial soil>purple soil>yellow soil under the same Cd concentration.2) The activities of antioxidant enzyme include SOD, POD, CAT increased at first and then decreased with the increase of Cd concentration in three types of soil. Soluble protein decreased with the increase of Cd concentration, but soluble sugar and MDA content increased when concentration of Cd increased. The physiological responses of Pennisetum sp was different among three types soil, Compared with other two kinds of soil, The change range of antioxidant enzyme activity and MDA content were smaller and soluble protein and chlorophyll content were higher in alluvial soil, it suggested that Pennisetum sp cultivated in alluvial soil had strong tolerance and less poisoned with Cd pollution.3) The C, N, P content of Pennisetum sp were changed by the four levels of Cd in the three types of soil. The C, N, P content of the aboveground part of Pennisetum sp were higer than the blowground part. The C content of Pennisetum sp had no significant effects during the Cd concentration in the expremint except in root.The P content of each organ in the alluvial soil was higherthan yellow soil and purple soil, possibly owning to fact that P was the limit clement in thetested soil.4) The Cd content of root, stem and leaf showed a significant increased tendency with the increase of Cd concentration with an order of root>leaf>stem in the three soil types. In addition, the Cd content of above ground parts was less than that of root, with the Cd content in each organ of Pennisetum sp higher in yellow soil than the other two soil types. The bioaccumulation coefficient and tolerance index of Pennisetum sp cultivated in yellow soil was higher than in other soil types, suggesting that Pennisetum sp had a better repairing effect in the Cd polluted yellow soil.In conclusion, Pennisetum sp had certain absorption and bioaccumulation characteristics in Cd contaminated soil, even with enrichment coefficient and transfer coefficient less than 1; It showed strong tolerance to Cd with Cd accumulation up to 1.24 mg/plant under 100 mg/kg treatment. The results indicated that Pennisetum sp has certain potential application value in phytoremediation of Cd contaminated soil.