Effects of Low Temperature on Seed Germination, Early Seedling Growth and Antioxidant Systems of the Wild Elymus nutans Griseb.

Low temperature is a limiting factor of seed germination and plant growth. In this study, two independent experiments were conducted to investigate the effects of low temperature on germination, early seedling growth and antioxidant systems in two provenances of Elymus nutans Griseb. (Damxung, DX and Gannan, GN). The seeds and early seedlings of DX were more tolerant to low temperture than those of GN. Low temperature (5 degrees C) negatively affected seed Germination Percentage (GP), Germination Energy (GE) and the First Germination Time (FGT) in both provenances of E. nutans. Low temperature also increased Mortality Percentage (MP) when compared with control plants grown at 25 degrees C. Low temperature treatments significantly reduced length and fresh/dry weight of shoots and roots in the two accessions after 29 days of exposure to 5 degrees C. In the second experiment, after 5 days of low temperature treatment, DX exhibited significantly higher Chlorophyll (Chl) and Carotenoid (Car) content as well as increased activities of Peroxidase (POD), SuperOxide Dismutase (SOD), Catalase (CAT). In contrast we observed lower Electrolyte Leakage (EL) and reduction of the amounts of MalonDiAldehyde (MDA), Hydrogen peroxide (H2O2) and superoxide radical (O-2(center dot-)). We conclude that GN is more susceptible to low temperature than DX due to more severe oxidative damage resulting from Reactive Oxygen Species (ROS) and lower antioxidant enzyme activities.