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

摘要： 为研究外源褪黑素（melatonin，MT）对低温胁迫下烟草幼苗生理指标的影响，以‘云烟87’为试验材料，设置0、50、100、150、200 μmol·L-1共5个MT浓度处理，探究低温胁迫下，不同MT处理对烟草幼苗活性氧代谢、渗透物质含量以及抗氧化酶活性的影响。结果表明，低温胁迫下烟草幼苗生长受到抑制，外源褪黑素能显著降低低温胁迫下烟草幼苗叶片中超氧阴离子（O-2）产生速率、过氧化氢（H2O2）含量和丙二醛（MDA）含量，提高烟草幼苗叶片中脯氨酸、可溶性蛋白及可溶性糖含量，增强超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）的活性，且100 μmol·L-1MT处理效果最佳。说明外源MT处理能够抑制低温条件下烟草幼苗叶片中活性氧的产生，降低膜脂过氧化水平，提高抗氧化酶活性，提高幼苗抵御低温胁迫的能力。

关键词: 褪黑素, 烟草幼苗, 低温胁迫, 生理指标