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

Abstract

Low temperature is a limiting factor of seed germination a nd plant growth. In this study, two independent experiments were conducted to investigate the effects of l ow temperature on germination, early seedling growth and antioxidant systems in two provenances of Elymus nutans Griseb. (Damxung, DX and Gannan, GN). The s eeds and early seedlings of DX were more tolerant to low temperture than those of GN. Low temperature (5 o C) negatively affected seed Germination Percentage (GP), Germination Energy (GE) and the First Germination Time (FGT) in both provenances of E. n utans . Low temperature also increased Mortality Percentage (MP) when compared with control plants grown at 25 o C. Low temperature treatments significantly reduced length and fresh/dry weight of shoot s and root s in the two accessions after 29 d ays of exposur e to 5 o C. In the second experiment, after 5 d ays of l ow 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 (H 2 O 2 ) and superoxide radical (   2 O ). We conclude that GN is more susceptible to l ow temperature than DX due to more severe oxidative damage resulting from Reactive Oxygen Species (ROS) and lower antioxidant enzyme activities . Keywords : Antioxidant systems , E arly seedling growth , Elymus nutans Griseb. , G ermination, Low temperature .