Abstract: In order to investigate the effect of exogenous abscisic acid on the ionic content of vegetative organs of alfalfa (Medicago sativa L.) seedlings with mixed soda salt-alkaline,WL343HQ alfalfa seed was used as the test material,and the seedlings were treated with 150 mmol·L^-1 mixed soda salt-alkaline stress and 25,50,75 and 100 μmol·L^-1 ABA. The changes of sodium (Na⁺),potassium (K⁺),calcium (Ca²⁺) and magnesium (Mg²⁺) ions in roots,stems and leaves of alfalfa seedlings were studied by atomic absorption spectrometry. The results showed that the contents of Na⁺,K⁺,Ca²⁺ and Mg²⁺ in different organs of alfalfa seedlings were different under mixed soda saline-alkali stress. The content of Na⁺ and Ca²⁺ in roots increased,the contents of K⁺ and Mg²⁺ decreased,and the contents of Na⁺,K⁺ and Mg²⁺ in stems increased,Ca²⁺ content decreased;Na⁺ and Mg²⁺ levels in leaves increased,and K⁺ and Ca²⁺ levels decreased. Root Na⁺ content,root and leaf K⁺ content,root and leaf Ca²⁺ content,root,stem and leaf Mg²⁺ content increased with the increase of ABA concentration in different organs of alfalfa seedlings treated with different concentrations of ABA. The content of Na⁺ in stems and leaves decreased with the increase of ABA concentration. The contents of K⁺ and Ca²⁺ in stems didn't change significantly with the increase of ABA concentration. The ratios of Na⁺/K⁺,Na⁺/Ca²⁺ and Na⁺/Mg²⁺ in each organ decreased with the increase of ABA concentration. It can be seen that the mixed soda saline-alkali stress affects the distribution of Na⁺,K⁺,Ca²⁺ and Mg²⁺ in the vegetative organs of roots,stems and leaves of alfalfa seedlings,and has certain correlation with the salt-tolerance of alfalfa seedlings.

Key words: Alfalfa, Abscisic acid(ABA), Mixed soda salt-alkaline stress, Vegetative organs, Mineral elements

摘要： 为了探究外源脱落酸（Abscisic acid，ABA）对混合苏打盐碱胁迫下紫花苜蓿（Medicago sativa L.）幼苗营养器官离子含量的影响，本试验以WL343HQ苜蓿种子为试验材料，对苜蓿幼苗进行150 mmol·L^-1混合苏打盐碱胁迫和25，50，75和100 μmol·L^-1ABA缓解处理，采用原子吸收法测定ABA缓解混合苏打盐碱胁迫下苜蓿幼苗根、茎和叶中钠（Na⁺）、钾（K⁺）、钙（Ca²⁺）和镁（Mg²⁺）离子含量的变化。结果表明：混合苏打盐碱胁迫导致苜蓿幼苗各器官的Na⁺，K⁺，Ca²⁺，Mg²⁺含量产生不同的变化；其中根中Na⁺和Ca²⁺含量增加，K⁺和Mg²⁺含量降低，茎中Na⁺，K⁺，Mg²⁺含量增加，Ca²⁺含量降低；叶中Na⁺和Mg²⁺含量增加，K⁺和Ca²⁺含量降低。经不同浓度的ABA处理的混合苏打盐碱胁迫后苜蓿幼苗各器官中，根中Na⁺含量、根和叶K⁺含量、根和叶Ca²⁺含量、根、茎和叶Mg²⁺含量均随ABA浓度增加而增加，茎和叶Na⁺含量随着ABA浓度的升高而下降，茎中K⁺和Ca²⁺含量随着ABA浓度的升高无明显变化。各器官中的Na⁺/K⁺，Na⁺/Ca²⁺和Na⁺/Mg²⁺比值均随着ABA浓度的升高而下降。可见，混合苏打盐碱胁迫影响苜蓿幼苗对Na⁺，K⁺，Ca²⁺，Mg²⁺在根、茎、叶营养器官的分布，与苜蓿幼苗的抗盐碱有一定的相关性。

关键词: 苜蓿, 脱落酸, 混合苏打盐碱胁迫, 营养器官, 矿质元素