NaHCO3胁迫下3种灌木Na+、K+、Ca2+的吸收及转运

通过盆栽试验,采用原子吸收分光光度法和非损伤微测技术,研究了NaHCO₃胁迫(300 mmol·L^-1)对大洋洲滨藜、四翅滨藜和宁夏枸杞3种灌木离子吸收及运转的影响.结果表明: 随着NaHCO₃浓度升高,两种滨藜和宁夏枸杞叶片中Na⁺含量升高,300 mmol·L^-1NaHCO₃胁迫下,宁夏枸杞叶肉细胞Na⁺的外排增加,两种滨藜净Na⁺外排降低;随着胁迫时间的延长,大洋洲滨藜和宁夏枸杞叶片的K⁺含量下降,Na⁺/K⁺升高,四翅滨藜叶片K⁺含量升高,Na⁺/K⁺降低;随着浓度的升高，宁夏枸杞叶片积累Ca²⁺减少,Na⁺/Ca²⁺高于对照,叶肉细胞Ca²⁺外排;两种滨藜叶Ca²⁺含量总体呈升高趋势，叶肉细胞Ca²⁺表现为内流.在NaHCO₃胁迫下,3种灌木通过不同的策略来消除Na⁺毒害.宁夏枸杞叶片Na⁺的积累抑制了对Ca²⁺的吸收;两种滨藜Ca²⁺的内流促使细胞质中游离Ca²⁺增加,增加的细胞质\Ca²⁺\]cyt防治质膜H⁺ ATPase去极化,限制K⁺的外排,从而维持细胞内Na⁺/K⁺的平衡,其中四翅滨藜调控Na⁺/K⁺平衡的能力较强.

Effect of NaHCO3 stress on uptake and transportation of Na+, K+ and Ca2+ in three shrub species.

We detected absorption and transportation of ions in the leaves of Atriplex nummularia, Atriplex canescens and Lycium barbarum under NaHCO₃ stress (300 mmol·L^-1) by using atomic absorption spectrophotometry and non-invasive ion flux measurement. The results showed that leaves of the A. nummularia, A. canescens and L. barbarum exhibited a high capacity to induce the Na⁺ accumulation when compared with that of control. The higher the concentration of NaHCO₃ treatment, the more Na⁺ accumulated in the leaves of the three plants under experimental condition. L. barbarum showed a higher Na⁺ efflux in the mesophyll cells, whereas A. nummularia and A. canescens showed a relative lower efflux. A lower K⁺ content and a higher Na⁺/K⁺ ratio were detected in leaves of A. nummularia and L. barbarum. However, a higher K⁺ content and a lower Na⁺/K⁺ ratio were seen in leaves of A. canescens. Due to induction of Ca²⁺ efflux under the NaHCO₃ treatment, a lower Ca²⁺ content and a higher Na⁺/Ca²⁺ratio were observed in L. barbarum. On the contrary, a higher Ca²⁺ influx was observed in A. nummularia and A. canescens. These results suggested that the three shrubs species had different Na⁺ segmentation strategies. The accumulation of Na⁺ inhibited Ca²⁺ absorption in leaves of L. barbarum, while in the A. nummularia and A. canescens, Ca²⁺ influx induced \Ca²⁺\]cyt which preserved a less depolarized PM and then inhibited K efflux. The maintaining of cellular K⁺/Na⁺ homeostasis in A.nummularia and A. canescens might be achieved by the induction of \Ca²⁺\]cyt under the NaHCO₃ treatment.