关键词: 褪黑素, 烟草幼苗, 低温胁迫, 生理指标

Abstract: In order to study the effect of exogenous melatonin (MT) on physiological response of tobacco seedlings to low temperature stress, taking tobacco variety  ‘Yunyan 87’ as test material, setting up 5 treatments, including 0, 50, 100, 150, 200 μmol·L-1 MT, this paper studied the effects of different treatments on active oxygen metabolism, osmotic substances contents, antioxidant enzymes activities of tobacco seedlings under low temperature stress. The results showed that the growth of tobacco seedlings was inhibited under low temperature stress. The superoxide anion (O-2) production rate, hydrogen peroxide (H2O2) content and malondialdehyde (MDA) content of tobacco leaves were significantly decreased under exogenous MT treatments, but the contents of proline, soluble protein and soluble sugar were increased, as well the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD). The treatment with 100 μmol·L-1 MT was the best. It was illustrated that exogenous MT could inhibit reactive oxygen species production, decrease the membrane lipid peroxidation, raise antioxidative enzyme activities, and then improve the resistance of seedlings to low temperature stress.

Key words: melatonin, tobacco seedling, low temperature stress, physiological property