Study On The Responses Of Switchgrass To Cd, Cu And Drought Stresses

For the advantages of high biomass and broad adaptability, switchgrass(Panicum Virgatum) attracted more and more attention. It is widely admitted that most published studies focused on the single stress, and ignored the coupling effects caused by the compound stresses. In viewing that, effects of cadium(Cd), copper(Cu) and drought on agronomic traits, photosynthetic physiology, stress resistance, absorption and transfer characteristics of heavy metals, water and mineral content were investigated, to provide a scientific basis for switchgrass phytoremediation under heavy metal polluted conditions in arid and semi-arid areas.The main results were as follows:1. With the increases of Cd and Cu concentration, compared with the control, the height and biomass on switchgrass increased and then decreased, acquired the maximum in Cd(110 mg/kg) and Cu(275 mg/kg) respectively. Carotenoid content and chlorophyll a/b increased, while total chlorophyll decreased, all acquired the maximum in Cd(200 mg/kg) and Cu(275 mg/kg) respectively.Cd and Cu content experienced a trend of increase, decrease and increase again, while water content had the opposite tendency. As the drought extent stepped up, height and biomass, chlorophyll and heavy metal indexes presented the complex trend.2. With the increases of Cd and drought extent, Vpd L, WUE and Ls decreased and then increased, acquired the maximum in Cd(200 mg/kg) and water(32%) respectively. REC, MDA and GSH content experienced the complex process, acquired the maximum in Cd(164 mg/kg) and water(50%) respectively. As the Cu concentration added, the indexes presented the complex trend, had the maximum in 500 mg/kg. And membrane lipid peroxidation indexes increased and then decreased, had the maximum in 50 mg/kg. With the increases of Cd, Cu or drought extent, Ls and K content decreased and then increased, while other mineral indexes experienced the complex process, all minerals acquired the maximum in Cd(20 mg/kg), Cu(500 mg/kg) and water(80%) respectively.3. Through the principal component analysis(PCA), the first principal component(PC) mainly showed the information of aboveground biomass, and the second to ninth PC reflected the information of Ls, root Cu, GSH, aboveground K, total chlorophyll, root biomass and MDA content. The two or three treatments had significant influence on chlorophyll a/b, Ls and root Fe.4. Switchgrass possessed the abilities to grow on heavy metal contaminated soils, and they can be planted large scale in arid and semi-arid areas under the heavy metal conditions.