盐渍生境下野生琵琶柴盐分分布及泌盐特点

对干旱盐渍环境下野生琵琶柴泌盐结构、泌盐规律及其与土壤盐分、植物盐分分布的关系进行了研究。研究表明 ,生长在硫酸钠盐土上的琵琶柴体内Na 、SO2 -4含量较高 ,其次是Cl-、Mg2 和K ,Ca2 含量最低。在一天之中植物体内含盐量保持稳定 ,叶片盐分离子含量高于枝条。光学显微观察显示 ,琵琶柴叶片具有多细胞盐腺 ,可分泌K 、Na 、Ca2 、Mg2 、Cl-和SO2 -4。其分泌细胞对于离子的分泌作用受到温度及昼夜变化的影响 ,表现为上午的分泌量高于下午 ,白昼高于夜间。盐腺对于不同离子的分泌速率表现为 :对于Cl-的分泌最高 ,其次是Na 和SO2 -4,而对于K 的分泌高于对Ca2 、Mg2 的分泌。但与植物叶片含盐量相比 ,琵琶柴盐腺对于Cl-的相对分泌远高于其他离子 ,分泌的盐分中Na/K比值高于植物体Na/K比值。以上结果表明 ,琵琶柴体内盐分离子含量与土壤盐分离子含量及其自身对于元素的吸收特性有关 ;而盐腺对于盐分的分泌作用在受到温度变化影响的同时 ,对离子分泌具有较高的选择性。琵琶柴对于不同元素的这种选择性吸收及分泌特性对适应盐渍生境有一定意义。

IONS SECRETION IN WILD REAUMURIA SOONGORICA UNDER NATURAL SALINE-ALKALI CONDITIONS

Investigations were carried out on structure of salt gland and secretion characteristics of salt excretion from xero-halophyte Reaumuria soongorica and their relationship with salt distribution in the soil and the plant under arid and saline-alkali conditions. Na and SO 2-_4 were the prominent ions in the soil solutions, as well as in the plant tissues, followed by K , Mg 2 , and Cl-,and the content of Ca 2 was the lowest. The internal salt contents, which were lower in the branches than in the leaves, were diurnally approximately constant. Na , K , Ca 2 , Mg 2 , Cl-, and SO 2-_4 could be secreted from its multi-cellular salt gland. The excretion rate was higher during the day than during the night and in the morning than in the afternoon, as was affected by temperature. Among the excreted ions, Cl- was the highest, followed by Na and SO 2-_4, and then K , Ca 2 and Mg 2 the lowest.In comparison with the salt content in the leaves, Cl- excreted from the salt grand was much higher over other ions. The ratio of Na/K in the secreted fluid were higher than that in the plant tissues. The above-described findings showed that the salt content in the plant was related to the salt content in the soil as well as the plant's characteristics of absorbing the elements; and the excretion of the salt grand was affected by temperature and irradiation and its high selectivity of ions. Such high selectivity for ions in absorption and excretion of Reaumuria soongorica is of high significance to the plant in adapting to the saline-alkaline habitat.