盐度对木榄幼苗某些金属元素累积的影响及钙的效应

通过对 40 0mmol·L^-1NaCl及不同浓度CaCl² 溶液处理的沙基培养的红树植物木榄幼苗各器官的K、Ca、Na、Mg含量的测定分析,结果表明,木榄幼苗在 40 0mmol·L^-1NaCl培养时各器官中积累大量的Na,造成K/Na和Ca/Na比值降低,幼苗干物质积累下降.补充Ca能减少Na在幼苗体内的累积,提高K/Na和Ca/Na,增加干物质积累,从而缓解盐胁迫,10～15mmol·L^-1CaCl² 为适宜浓度.本文的结论是在高盐度培养时木榄幼苗能够吸收大量的无机离子,增强渗透调节能力,保持对K/Na的高选择吸收性.这些特性是木榄对河口、海岸高盐度生境适应的主要生理机制,而生境土壤中适宜的Ca/Na也是其能够生存繁衍的重要原因之一.

Impact of salinity on accumulation of several metal elements in Bruguiera gymnorrhiza seedlings and Ca effect

The contents of K, Ca, Na and Mg in different organs of Bruguiera gymnorrhiza seedlings cultured in sand bases with solutions of 400 mmol.L-1 NaCl and different concentrations of CaCl2 were determined. In the treatment of 400 mmol.L-1 NaCl, Na was largely accumulated in organs, which caused the decrease of K/Na and Ca/Na, and decreased dry matter accumulation in seedlings. Supplemental CaCl2 decreased the accumulation of Na in seedlings, increased the rations of K/Na and Ca/Na and the accumulation of dry matter, and thereby, mitigated salt stress. The suitable concentration of CaCl2 was 10-15 mmol.L-1. It was concluded that B. gymnorrhiza seedlings cultured at high salinity accumulated more metal ions, which enhanced osmotic adjustment of plants, and kept highly selective absorption of K/Na. These characteristics are the main physiological mechanisms of the adaptation of B. gymnorrhiza to high salinity in estuary and coast, while suitable Ca/Na in soil is one of the important causes that B. gymnorrhiza can survive and regenerate in high salinity coast.