盐胁迫对砂蓝刺头不同器官中离子分布的影响

Effects of salt stress on ion distribution in different Echinops gmelini organs

砂蓝刺头为广泛分布于北方沙漠的一年生草本植物。本研究以砂蓝刺头幼苗为试材,采用营养液培养法研究了不同浓度NaCl胁迫下(盐浓度分别为0,100,200,300,400mmol/L)砂蓝刺头幼苗胁迫6d后植株含水量变化,测定不同器官中Na+、Cl-、Si 4+、K+、Ca2+的含量,并分析了K+/Na+、Ca2+/Na+、Si 4+/Na+值的变化。研究结果表明,盐胁迫下,砂蓝刺头幼苗含水量在盐处理浓度为100,200,300,400 mmol/L时分别比对照升高了9.86%,1.41%,4.23%,8.45%,说明盐胁迫下植株提高了组织含水量,这将在一定程度上稀释了体内盐离子,减弱盐胁迫造成的生理干旱。盐胁迫下砂蓝刺头根部的Na+和Cl-含量高于叶片,这有利于渗透调节,同时减弱了盐胁迫对地上部的毒害;根系Si 4+、K+、Ca2+的含量及K+/Na+、Ca2+/Na+、Si 4+/Na+值比对照显著性下降,叶部Si 4+、K+的含量和K+/Na+,Ca2+/Na+,Si 4+/Na+值比对照有所增加或差异不显著,这有利于维持地上部分离子稳定。分析离子选择性吸收的SNa+,K+数据发现,盐胁迫下砂蓝刺头根部拦截了部分Na+减缓了对地上部分的伤害,叶片对K+吸收具有很好的选择性,对于维持地上部分离子平衡和正常的光合作用具有重要意义。

Echinops gmelini is an annual wild plant distributed in arid desert areas of North China. The changesof water content, Na＋ , C1- , Si4＋ , K＋ , Ca2＋ contents and the K＋/Na＋ , Ca2＋/Na＋ , Si4＋/Na＋ ratios weremeasured in E. gmelini seedlings in a water control and under different concentrations （100, 200, 300, 400mmol/L） of NaC1 stress： the water contents were found to increase by 9. 86%, 1.41%, 4. 23%, and 8.45%,respectively. Therefore the ability to absorb water was enhanced under salt stress, resulting in dilution of thecell＇s salt ion concentration to reduce physiological drought caused by salt ions. Na＋ and C1- contents of rootswere higher than those of leaves under salt stress, so the salt ion damage on the leaves was redueed The Si4% ,K＋ , Ca2＋ concentrations and K＋/Na＋, Ca2＋/Na＋ , Si4./Na＋ ratio in roots under salt stress were significantlyreduced compared with no salt stress. Based on the ion selective absorption of Nat and K＋ , E. gmelini rootsretained more Na＋ and reduced the Na＋ damage to leaves; The K＋ selective absorption to leaves of E. gmeliniwere strengthened under NaC1 stress, which was significant for maintaining iron homeostasis and photosynthe-sis in shoots.