钠钾离子替代对椰子叶片叶绿素、丙二醛、离子含量的影响

为探讨不同钠替代钾条件下椰子叶片叶绿素、丙二醛及Na+、K+含量的变化，在沙培环境中对椰子苗进行钠替代钾试验。结果显示：在Na+、K+总浓度为4 mmol/L的情况下，与100%钾的对照相比，25%的钠替代钾处理中叶绿素a、叶绿素b、总叶绿素含量上升；50%、75%处理明显下降，100%处理略有下降；各处理Chla/Chlb比值变化趋势基本一致，总体趋于平稳且各处理间差异不显著(P＞0.01)。随时间的推移，25%、50%处理丙二醛(MDA)含量与对照相当，趋于平稳，而75%、100%处理丙二醛(MDA)含量呈上升变化。80 d后，各处理的Na+含量随着钠替代钾比例的上升而逐渐增加，较之对照均达到了极显著水平(P＜0.01)；而25%、50%、75%的K+含量略低于对照但差异不显著(P＞0.01)，且各处理间差异也不显著(P＞0.01)，100%处理K+含量明显低于其他各处理且均达到了极显著水平(P＜0.01)。结果表明：部分钠替代钾处理对椰子苗的叶片光合色素及K+含量没有影响甚至有促进作用，表现出一定的耐盐能力。

Effect of the Replacement of Potassium by Sodium on Contents of Chlorophyll, Malonaldehyde and Ions in the Coconut Leaves

In order to study the change of contents of chlorophyll, malonaldehyde and ions under the condition of the different proportional replacement of potassium by sodium in the coconut leaves, a test was attempted in which the replacement of potassium by sodium in the coconut leaves was carried out under the sand culture. The result showed that in a condition of which the total concentration of potassium and sodium was 4 mmol/L, compared to 100% treatment, the contents of chlorophyll a, chlorophyll b, total chlorophyll increased in the treatment of 25% replacement of potassium by sodium; decreased obviously in 50% and 75%, but reduced slightly in 100%. The tendency of changes of the ratios of chlorophyll a/b in all treamts was not only nearly alike and gradually steady, but also the difference between them was not significant (P>0.01). As time went, the contents of malonaldehyde was equal to the control and steady in the treatments of 25%, 50% replacement of potassium by sodium, but rose in 75% and 100%. After 80 days, Na contents in all treatments increased gradually with the increasing proportional replacement of potassium by sodium, compared to the control, which were extremely significant (P<0.01); however, K contents in the treatments of 25%, 50%, 75% replacement of potassium by sodium were slightly lower than the control, as well as non-significant(P>0.01), moreover, there were not significant (P<0.01) between them. K contents in 100% decreased apparently and were extremely significant (P<0.01), compared with other treatments. The results of the study expounded that the partial replacement of potassium by sodium had no or positive effect on contents of chlorophyll and K+ in the coconut leaves, displaying the ability of salt tolerance to a certain degree.