酸、碱、盐胁迫下千层金幼苗的生理指标变化研究

以千层金实生苗为材料，采用盆栽模拟试验，研究不同浓度酸、碱、盐胁迫连续15天和30天对千层金幼苗的形态、叶片含水量、叶绿素含量、脯氨酸含量、丙二醛含量以及SOD活性的影响。结果表明，不同处理的植株与对照（ CK）相比，除了pH值为4和11条件下植株出现叶片枯萎脱落现象，叶片含水量呈下降趋势以外，其余的在形态上没有太大的变化，表明千层金幼苗对酸、碱胁迫有一定的抗性，在pH值为5～10浓度处理下的植株均能正常生长；随着胁迫时间的延长，叶绿素含量以pH值为8的居高，随着pH值的降低和升高，均呈现逐渐降低的趋势，而丙二醛含量、脯氨酸含量以及SOD活性均明显高于对照（ CK）；用不同浓度混合盐碱对千层金幼苗进行胁迫处理，随着浓度的增大，脯氨酸含量和SOD活性呈先升后降的趋势，丙二醛含量不断增加，当pH值大于9， NaCl浓度在0.3％以上的盐碱混合胁迫处理15天以后，千层金幼苗植株受伤害程度不断加大。

Variation of Physiological Indexes of Melaleuca bracteata Seedlings under Acid,Alkali and Salt Stress

Through pot culture experiment , the reaction of Melaleuca bracteata seedlings to acid , alkali and salt stress of different concentrations between 15 d and 30 d were studied .The studied indexes included the basic mor-phological characteristics, the contents of leaf water, chlorophyll, proline, MDA and the activity of SOD.There was no significant change on plant morphological traits within the pH range of 5~10 , whereas under the pH of 4 and 11, the phenomenon of leaves wither shedding and the leaf water content decrease occurred , which verified that Melaleuca bracteata seedlings had some resistance to acid and alkali stress .As the stress continued , it was found that the chlorophyll content under the treatment of pH 8 was higher than the seedlings under other pH treat-ments, however the contents of MDA and proline , and the activity of SOD were significantly higher than the con-trol （CK）.Using different concentrations of salt-alkaline mixed stresses to treat Melaleuca bracteata seedlings, the content of proline and the activity of SOD went up first and then fell down with the increase of concentration , but the content of MDA showed the tendency of continuously increasing . The results showed that the salt-alkaline mixed stresses with pH 〉9 and the concentration of NaCl higher than 0.3 %, the damage extent of the treated plants continuously increased after 15 days stress treatment .