盐碱芦苇（Phragmites australis）湿地近年来备受关注，其在维持湿地物种多样性和系统平衡方面起着重要作用。芦苇是世界广布的湿地植物，其生态幅极广，在极端条件下均能表现出较强的抗逆性，在5‰~65‰的盐度环境中皆能生长。芦苇具有富集盐分的能力，对降低盐碱度具有重要的意义。但过高的盐分也对芦苇生长发育造成负面影响。当今世界范围内土壤盐渍化问题日益严重，全世界拥有占耕地面积约10%的盐渍土，盐胁迫已经成为影响植物生长发育的重要逆境因素之一。根系是盐进入生态链的门户，是植物受盐伤害最直接的部位，根系分泌物能够直接体现盐胁迫对植物造成的影响。作为植物与外界进行交流的重要媒介，根系分泌物的行为具有重要的生态学意义。本试验以芦苇为研究对象，设置了5个NaCl胁迫梯度0（对照）、1‰、3‰、6‰、10‰和4个胁迫时间1h、2h、4h、12h。采用GC-MS对根系分泌物的组分进行了定性分析，用HPLC对根系分泌物中的氨基酸成分进行了定性、定量分析。系统的研究了不同盐度及其胁迫时间下芦苇根系分泌物种类与含量的变化，为揭示盐胁迫和根系分泌物之间的关系提供参考。试验取得以下主要研究结果：（1）利用GC-MS从芦苇根系分泌物的二氯甲烷萃取物中一共检测出了99种可能存在的化合物，这些化合物包括烷烃类、烯烃类、芳烃类、醇类、酚类、醚类、酮类、醛类、酸类、酯类、噻唑类以及其他硫代、卤代化合物等，其中烷烃类是各样品中检出的种类最多的化合物。随着盐浓度的增加，经较短时间胁迫的样品中化合物种类呈现先减少后增加的趋势，经较长时间胁迫的样品中化合物种类大致呈先增加后减少的趋势。在不同胁迫时间下，化合物总量均随盐度增加大体呈减少趋势。（2）芦苇根系分泌物中共检测出了18种氨基酸，盐胁迫对氨基酸种类和数量影响显著。单一种类氨基酸和总量均随胁迫时间的延长呈现先增加后减少的趋势，但随盐度的变化没有表现出一致的规律性。脯氨酸对盐度的响应比其他氨基酸敏感，其分泌量和增加速度显著高于其他种类氨基酸。

Reed saline-alkali wetlands have attracted much attention in recent years.as they playsan important role in maintaining the wetland species diversity and the balanced system. It is well known that Phragmites australis (P. australis) is a widespread species growing in both freshwater and saline habitats. Recent literatures pointed out that limits of salt tolerance on P. australis vary widely between 5% and 65%. P. australis has the ability to enrich salt in soil and improves saline-alkali soil, but excessive salt also have a negative impact on P. australis growth. Soil salinization becomes more and more serious worldwide, with about 10% of the world’s land surfaces being saline soil. Salt stress has become one of the most important environmental stresses affecting physiological traits and quality of wetland plants world-wide. Roots of plants are the gateway of ecological chain and will be directly injured by salt. Root exudates can directly reflect the effects of salt stress on plant. As an important medium of plant to communicate with the outside world, the behavior of the root exudates has vital ecological significance.This experiment took P. australis as experimental materials. Designing five NaCl concentration gradients 0 (control group), 1‰, 3‰, 6‰, 10‰ and four exposure time 1h, 2h, 4h, 12h. Qualitatively analysis of root exudates with GC-MS’s fully automatic scan mode, qualitatively and quantitatively analysis of amino acids of root exudates with HPLC instrument, studied the effects of exposure levels and exposure time on root exudates of P. australis, providing the theory bases of the salt stress and root exudates. Following conclusions were reached by the experiment.(1) Choose dichloromethane as the extraction agent, 99 kinds of compounds were detected in P. australis root exudates using GC-MS, including alkanes, olefins, arenes, alcohols, phenols, ethers, ketones, aldehydes, acids, esters, thiazoles and other sulphured or halogenated compounds, and compounds in alkane series were higher than others. With the increase of salt concentration, types of detected compounds of shorter exposure time treatments reduced first and then increased, types of detected compounds of longer exposure time treatments increased first and then went down. In every different exposure time, the amount of detected compounds almost displayed the downtrend with the increase of salinity.(2) Eighteen kinds of free amino acids were detected from root exudates. The amount of amino acids among different samples and the amount between different amino acids varied a lot. With the extension of stress time, the amount of all amino acids showed the same trend, increased first and then went down. With the extension of stress time, the amount of every amino acid increased firstly and then decreased in general, but did not showed consistent regularity with the salinity change. Proline showed more sensitive character than other amino acids when stressed by salt, its exudate amount and rate occupied higher level than other amino acids.