为了解Na＋在植物盐境生长时发挥的作用，笔者采用不同浓度的NaCl（0，300，600，900mmol·L-1）处理，研究盐生草本植物海马齿（Sesuvium portulacastrum）叶片中Na＋和K＋的变化规律。结果表明，300mmol·L-1的NaCl处理条件下海马齿的生物量显著增加；原子吸收光谱与X-Ray-能谱-扫描电镜分析结果显示，海马齿的叶片中积累了大量的Na＋，且随着NaCl浓度的增加，Na＋含量呈显著增加而K＋含量降低。这表明Na＋作为海马齿的营养元素在一定浓度范围内可以促进植株生长，但其浓度过高时则影响钾离子的吸收产生毒害作用。%Although regarded as one of the major cations contributing to soil salinity, sodium was also reported to be beneficial to plant growth. To elucidate the function of sodium in plants under salt stress, seedlings of Sesuvium portulacastrum were treated with NaC1 at different concentrations （0,300,600,900 mmol · L- 1 ） to observe the leaf morphology, biomass weight and Na ＋ and K ＋ content. The results showed that the seedlings treated with 300 mmol ·L-1 NaGl produced the highest biomass. The flame emission and X-Ray microanalysis showed that large mounts of sodium ions were accumulated in the leaves, and that the leaf Na ＋ content was increased dramatically with the NaC1 concentration while the leaf K ＋ content decreased, which leads to a high Na ＋/K ＋ ratio.This study suggests that sodium of a given range of concentration could improve plant growth but high levels of sodium reduce uptake of K ＋ by the plant, hence leading to toxicity to the plant growth.
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