以狗牙根〔Cynodon dactylon (Linn.) Pers.〕品种‘阳江’（‘Yangjiang’）为实验材料、2-(N-吗啡啉)乙磺酸（MES）为pH缓冲剂，采用水培法研究NaCl胁迫下pH值和氮素形态（铵态氮和硝态氮）对狗牙根生长和钠钾离子调控的影响。结果表明：处理1周后，若不添加MES，铵态氮处理组培养液的pH值下降到pH 4.0左右，而硝态氮处理组培养液的pH值则上升到pH 9.0左右；添加20 mmol·L^-1MES的铵态氮处理组培养液的pH值也下降到pH 4.0左右，而硝态氮处理组培养液的pH值则接近pH 7.0。与0 mmol·L^-1NaCl处理组相比，300 mmol·L^-1NaCl处理组狗牙根的枝条长度和枝条干质量显著（P＜0.05）下降，而根长度、根干质量、根和叶中Na⁺含量和Na⁺/K⁺比、钠钾选择性转运系数、叶Na⁺和K⁺的分泌量及分泌物Na⁺/K⁺比总体上显著升高。300 mmol·L^-1NaCl胁迫下，硝态氮处理组狗牙根的枝条长度、根长度、根干质量、根冠比、根中Na⁺含量总体上显著高于铵态氮处理组，而叶中Na⁺和K⁺含量及Na⁺/K⁺比、叶Na⁺和K⁺的分泌量明显低于铵态氮处理组。300 mmol·L^-1NaCl胁迫下，20 mmol·L^-1MES处理组狗牙根的多数生长指标显著高于0 mmol·L^-1MES处理组，而根和叶中Na⁺和K⁺含量及Na⁺/K⁺比、钠钾选择性转运系数在0和20 mmol·L^-1MES处理组间的差异不显著。三因素方差分析结果表明：3个因子的单一和交互作用对多数生长指标、叶中Na⁺含量和泌盐量相关指标的影响具有统计学意义。研究结果显示：硝态氮能缓解NaCl胁迫对狗牙根的伤害，而用MES缓冲根际酸碱环境对NaCl胁迫下狗牙根生长有一定的促进作用，因此，施用硝态氮或添加MES均有利于提高狗牙根的抗盐性。

Taking cultivar ‘Yangjiang’ of Cynodon dactylon (Linn.) Pers. as research material and 2-(N-morpholino) ethanesulfonic acid (MES) as pH buffer agent, the effects of pH value and nitrogen form. (ammonium nitrogen and nitrate nitrogen) on growth and sodium and potassium ion regulation of C. dactylon under NaCl stress were studied by using water culture method. The results show that, after treatment for one week, the pH value of culture solution in ammonium nitrogen treatment group without adding MES decreases to about pH 4.0, while that in nitrate nitrogen treatment group increases to about pH 9.0; the pH value of culture solution in ammonium nitrogen treatment group with adding 20 mmol·L^-1 MES also decreases to about pH 4.0, while that in nitrate nitrogen treatment group approaches pH 7.0. Compared with 0 mmol·L^-1 NaCl treatment group, the shoot length and dry mass of shoot of C. dactylon in 300 mmol·L^-1 NaCl treatment group significantly (P＜0.05) decrease, while the root length, dry mass of root, Na⁺ content and Na⁺/K⁺ ratio of root and leaf, selective transport coefficient of sodium and potassium, Na⁺ and K⁺ secretion levels and Na⁺/K⁺ ratio of secretion of leaf significantly increase in general. Under 300 mmol·L^-1 NaCl stress, the shoot length, root length, dry mass of root, root/shoot ratio, Na⁺ content in root in nitrate nitrogen treatment group are significantly higher than those in ammonium nitrogen treatment group in general, while the Na⁺ and K⁺ contents and Na⁺/K⁺ ratio of leaf and Na⁺ and K⁺ secretion levels of leaf are obviously lower than those in ammonium nitrogen treatment group. Under 300 mmol·L^-1 NaCl stress, most growth indexes of C. dactylon in 20 mmol·L^-1 MES treatment group are significantly higher than those in 0 mmol·L^-1 MES treatment group, while the differences in Na⁺ and K⁺ contents and Na⁺/K⁺ ratio of root and leaf, selective transport coefficient of sodium and potassium between 0 and 20 mmol·L^-1 MES treatment groups are not significant. The result of three-factor analysis of variance shows that there are statistical significances in effects of single effect and interaction of the three factors on most growth indexes, Na⁺ content in leaf, and salt secretion related indexes. It is suggested that nitrate nitrogen can alleviate the damage of NaCl stress on C. dactylon, while buffering rhizosphere acidic-base environment with MES has a certain promoting effect on the growth of C. dactylon under NaCl stress. Therefore, the application of nitrate nitrogen or the addition of MES is beneficial to improve the salt tolerance of C. dactylon.