Abstract

Chilling stress is one of main constraint factors for tobacco production in many regions of the world.  In order to study the lipid peroxidation and antioxidant system of flue-cured tobacco seedling after chilling stress, the experiment was conducted with different stressful period which was 2, 4 and 6 days under 5 to 7°C by the material named Yunyan87, Msk326 and Yunyan85, respectively. The results indicated that the rate of O₂^- production in leaves of three cultivars significantly declined at short-term (2 to 4 days) chilling stress. The malondialdehyde (MDA) contents and electric conductivities presented increasing at 2 to 4 days chilling treatments for YY87 and YY85 while those were similar to that of control seedling for K326. Superoxide dismutase (SOD) activities of YY87 remained similar to that of control plants while SOD activities of K326 and YY85 took reverse change. Catalase (CAT) and peroxidase (POD) activities of YY87 and YY85 enhanced under chilling stress, and reached remarkable difference under 6 days chilling stress; As for K326, CAT activities were the maximum under 4 days chilling stress, and POD activities had a prominent decline under 2 days cold stress and increased significantly after that. Except glutathione (GSH) contents of YY87 declined at 6 days chilling, the contents of ascorbic acid (ASA) and glutathione (GSH) were significantly higher in leaves of others treatments comparing with that of controls.

Key words: Chilling stress, flue-cured tobacco, lipid peroxidation, antioxidant enzymes, ascorbic acid, glutathione.