Abstract: In order to reveal the physiological mechanism of exogenous melatonin improving the resistance to salt stress of Phragmites communis L.,  0.01 mmol/L exogenous melatonin was applied to P. communis seedlings stressed with 150 mmol/L NaCl. The physiological characteristics, including dry matter accumulation, photosynthetic characteristics, antioxidant enzyme activities, osmotic adjustment content and malondialdehyde (MDA) content of P. communis seedlings were tested. The results showed that salt stress inhibited the growth and dry matter accumulation of P. communis seedlings, and caused serious physiological damage to seedlings. Spraying exogenous melatonin could increase the chlorophyll content and photosynthetic performance of P. communis seedling leaves, and increase the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and the content of osmotic adjustment substances, such as proline and soluble protein, reduce the content of reactive oxygen and MDA. Therefore, foliage application of melatonin could increase antioxidant enzymes activity and the accumulation of osmotic adjustment substances in the leaves of P. communis under salt stress, and effectively remove excess reactive oxygen species, alleviate oxidative damage and enhance the salt tolerance of P. communis seedlings.

Key words: melatonin, salt stress, reed seedlings, physiological characteristics

摘要： 为了揭示外援褪黑素提高芦苇抗盐胁迫能力的生理机制，以芦苇幼苗为试验材料，探究叶片喷施外源褪黑素（0.01 mmol/L）对盐胁迫下（150 mmol/L NaCl）芦苇幼苗干物质积累、光合特性、抗氧化酶活性、渗透物质含量以及丙二醛（malondialdehyde，MDA）含量的影响。结果表明：盐胁迫抑制了芦苇幼苗的生长和干物质积累，对幼苗造成严重的生理伤害。喷施外源褪黑素通过增加芦苇幼苗叶片叶绿素含量和提高光合性能，提高超氧化物岐化酶（superoxide dismutase, SOD）、过氧化物酶（peroxidase, POD）和过氧化氢酶（catalase, CAT）的活性，增加脯氨酸、可溶性蛋白等渗透调节物质含量，降低活性氧和MDA含量，缓解盐胁迫对芦苇幼苗的生长抑制。因此，叶面喷施褪黑素通过提高盐胁迫下芦苇幼苗叶片抗氧化酶活性和渗透调节物质积累量，有效清除过量的活性氧，缓解氧化损伤，来增强幼苗的抗盐胁迫能力。

关键词: 褪黑素, 盐胁迫, 芦苇幼苗, 生理特性