Abstract: In order to reveal the physiological effects of exogenous melatonin (MT) on tobacco drought resistance ability, taking Yuyan 10 as experimental material this paper conducted hydroponic experiment and explored the effects of different concentrations MT (50 μmol/L, 100 μmol/L, 200 μmol/L, 500 μmol/L) on tobacco seedlings membranous peroxide, osmotic regulation substances content, antioxidant enzyme activity and photosynthetic characteristics under drought stress. The results showed that drought stress could cause serious damage to physiological function of tobacco seedlings, and the treatments with 50 μmol/L or 500 μmol/L MT had no better mitigating effect on drought stress. While, 100 μmol/L MT could increase the chlorophyⅡ content and photosynthetic rate; enhance activities of superoxide disproportionation enzyme (SOD), peroxidase (POD), catalase (CAT); remove active oxygen free radicals; decrease malondialdehyde (MDA) content; increase accumulation of soluble protein and proline osmotic regulatory substances; improve leaf moisture content and reduce water loss rate, thus effectively alleviated the damage caused by drought stress.

Key words: tobacco seedlings, drought stress, melatonin, physiological characteristics

摘要： 为了揭示外源褪黑素（MT）提高烟草抗旱能力的生理效应，以豫烟10号为供试材料，采用水培实验，探究了干旱胁迫下不同浓度（50 μmol/L、100 μmol/L、200 μmol/L、500 μmol/L）MT对烟草幼苗膜脂过氧化物、渗透调节物质含量、抗氧化酶活性及光合特性的影响。结果表明：干旱胁迫对烟草幼苗的生理功能造成严重损害，50 μmol/L和500 μmol/L MT处理对干旱胁迫的缓解效果不佳，而100 μmol/L MT处理能够提高叶绿素含量和光合速率，增强超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性，清除活性氧自由基，降低丙二醛（MDA）含量，增加可溶性蛋白和脯氨酸渗透调节物质的积累，提高叶片含水率，降低失水率，有效缓解了干旱胁迫的伤害。

关键词: 烟草幼苗, 干旱胁迫, 褪黑素, 生理特性