摘要： 为了探究不同外源褪黑素浓度对盐渍环境下黄瓜幼苗生长的影响，以黄瓜新泰密刺为试材，采用叶面喷施方法，研究中度盐渍环境下不同外源褪黑素浓度（0，50，100，150，200 μmol/L）对黄瓜幼苗的生长指标、渗透调节物质、抗氧化酶活性、光合色素含量及叶片酶活性和相对电导率的影响。结果表明，外源褪黑素浓度为100 μmol/L的处理较150，200 μmol/L的处理更能显著提高盐渍环境下黄瓜幼苗抵抗逆境的能力，幼苗的株高、茎粗、叶长和叶宽分别较0 μmol/L提高了21.0%，6.0%，5.8%和6.0%，促进了植株的生长；黄瓜幼苗的SOD、POD和根系活力分别较0 μmol/L分别提高了95.8%，3.6%和39.2%，MDA含量和叶片相对电导率分别较0 μmol/L降低了23.7%和8百分点，表明褪黑素处理提高了清除活性氧的能力，减少了膜脂过氧化对黄瓜幼苗细胞的伤害；叶绿素a含量较对照提高了37%；处理15 d后，处理组M2幼苗的初始荧光值（Fo）与最大荧光值（Fm）均显著高于对照，光能转化率（Fv/Fm）与对照之间无显著差异；渗透调节物质可溶性蛋白、脯氨酸和可溶性糖含量分别较对照显著提高了13.8%，37.5%和3.6%。因此，100 μmol/L浓度的外源褪黑素处理黄瓜幼苗时，不仅可促进黄瓜幼苗的生长，还提高了黄瓜幼苗在盐渍环境下的抗逆性。

关键词: 黄瓜幼苗, 褪黑素, 盐渍环境, 生理特性

Abstract: To explore the effects of different exogenous melatonin concentrations on the growth of cucumber seedlings in a saline environment, in the experiment, cucumber Xintai Mici was used as the test material, and the method of foliar spraying was used to study the effect of different exogenous melatonin concentrations (0, 50, 100, 150, 200 μmol/L) in a moderately saline environment on cucumber seedling growth indicators, osmotic adjustment substances, antioxidant enzyme activity, photosynthetic pigment content, leaf enzyme activity and relative conductivity. The results showed that the treatment with an exogenous melatonin concentration of 100 μmol/L could significantly improve the resistance of cucumber seedlings to stress in a saline environment, and the plant height, stem thickness, leaf length and leaf width of the seedlings was better than the treatments with the melatonin concentrations of 150, 200 μmol/L, and increased by 21.0%, 6.0%, 5.8% and 6.0%, respectively, compared with the control, which promoted plant growth. The SOD, POD and root activity of cucumber seedlings increased by 95.8%, 3.6% and 39.2%, compared with the control, the MDA content and the relative conductivity of the leaves reduced by 23.7% and 8 percentage point, respectively, compared with the control, indicating that the melatonin treatment improved the ability to remove active oxygen and reduced the damage of membrane lipid peroxidation to cucumber seedling cells. Its chlorophyll a content increased by 37%, compared with the control. After 15 d of treatment, the initial fluorescence value (Fo) and maximum fluorescence value (Fm) of M2 seedlings were significantly higher than those of the control. There was no difference between the value of light energy conversion rate (Fv/Fm) and the control. The contents of osmotic regulator soluble protein, proline and soluble sugar significantly increased by 13.8%, 37.5% and 3.6%, respectively, compared with the control. Therefore, when cucumber seedlings are treated with exogenous melatonin at a concentration of 100 μmol/L, it not only promotes the growth of cucumber seedlings, but also improves the stress resistance of cucumber seedlings in a saline environment.

Key words: Cucumber seedlings, Melatonin, Saline environment, Physiological characteristics

中图分类号: 

• S641.9