以冰叶日中花(Mesembryanthemum crystallinum L.)实生苗为材料,经NaCl、NaCl+ CaCl2、NaCl+ LaCl3处理后,利用电感耦合等离子发射光谱仪检测叶、茎、根中Na+、K+、Ca2+、Mg2+含量,计算K+/Na+、 Ca2+/Na+和Mg2+/Na+比值,利用非损伤微测技术测定根尖Na+流和K+流,研究盐胁迫下钙在维持离子平衡中的作用.结果显示,NaCl处理后,冰叶日中花各器官中Na+含量增加,K+、Ca2+、Mg2+含量降低,离子比值降低; CaCl2处理降低了Na+含量,提高了K+、Ca2+、Mg2+含量,离子比值升高,而LaCl3处理后的结果相反.经NaCl处理24 h后,冰叶日中花根尖Na+和K+明显外流,加入CaCl2后,Na+外流速度显著增加,K+外流速度受到抑制,而加入LaCl3后则降低了Na+的外流速度,促进了K+的外流.研究结果表明冰叶日中花受到盐胁迫后,钙参与了促进根部Na+外排、抑制K+外流的过程,进而保持各器官中较低的Na+含量,表明钙在维持和调控离子平衡中起到重要作用.%In this study,the seedlings of Mesembryanthemum crystallinum L. were used as plant material. After treatment with NaCl,NaCl + CaCl2,and NaCl + LaCl3,the contents of Na+,K+, Ca2+,and Mg2+ in the leaves,stems,and roots were tested using ICP-OES,with the values of K+ /Na+,Ca2+ /Na+,and Mg2+ /Na+ also calculated to explore the role of calcium in maintaining ion balance under NaCl stress. The fluxes of Na+ and K+ were also determined by the noninvasive micro-test technique (NMT). Results showed that after NaCl treatment,the content of Na+ in the three plant organs increased,whereas the contents of K+,Ca2+,and Mg2+ decreased,as did the ion content ratios. The addition of CaCl2 reduced the content of Na+, but increased the contents of K+,Ca2+,and Mg2+ as well as the ion content ratios. Conversely, LaCl3 treatment caused the opposite results. After treatment with NaCl for 24 h,significant effluxes of Na+ and K+ were found in the root tip,indicating that M. crystallinum L. was in a state of ionic imbalance. After the addition of CaCl2,the efflux rate of Na+ increased obviously, whereas that of K+ was inhibited. Conversely,the addition of LaCl3 reduced Na+ efflux but accelerated K+ efflux. The above results suggested that when M. crystallinum L. exposed to salt stress,calcium promoted Na+ efflux but reduced K+ efflux in the root tips,and maintained lower Na+ content in the three plant organs,suggesting that calcium plays an important role in maintaining and regulating ionic balance.
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