獐茅盐腺形态结构及其泌盐性

显微观察结果显示，獐茅盐腺为典型的双细胞结构，主要分布在叶脉附近，这样有利于它快速收集来自根部的盐离子。同时，X-ray微区分析结果表明，獐茅盐腺可以有效地将Na^＋从表皮细胞和叶肉细胞转运到基细胞，由帽细胞分泌到体外，从而降低植物体内盐分水平以适应盐渍环境。用不同盐类处理材料，獐茅对Na^＋、K^＋和Ca^2＋的吸收和分泌均表现为具有不同的选择性，分泌量的顺序为Na^＋〉K^＋〉Ca^2＋，并且仅仅24h内，盐分的分泌量就已经超过了叶片内的含量，结果植株体内的总离子含量水平几乎不变，说明獐茅具有较强的泌盐能力。

The Morphological Structure of Salt Gland and Salt Secretion in Aeluropus littoralis var. sinensis Debeaux

The leaves of Aeluropus littoralis var. sinensis Debeaux were scanned with a scanning electron microscope, it showed that the upper-epidermis had almost the same number of salt glands as the lower-epidermis (Plate I-1, 2), and the salt gland is the typical bicelluar gland, which consists of a large basal cell inlaid into the epidermis and a small cap cell (Plate I-6). These salt glands were distributed mainly on the leaf veins, which favors the rapid collection of salts from the roots. Ion X-ray microanalysis indicated that the salt glands could effectively absorb Na(+) from the epidermal cells and mesophyllous cells (Table 1), then secreted Na(+) from the cap cells (Plate I-4), which would decrease the salinity of plant. After the plants were treated with various salts for 17 d, the ion contents of the leaves and the secretion were measured, and the results implied that salt glands had different selection in absorbing and secreting Na(+) , K(+) and Ca(2+), that is, the plants first selected K(+) when absorbing ions, while first selected Na(+) when sending ions out, but Ca(2+) was fewer in both absorbed and secreted, and the order of secretion of the three ions was found to be Na(+)>K(+)>Ca(2+) (Figs. 1-6). The secretion of Na(+) or three ions were respectively higher than that of leaves within 24 h (Figs. 1, 2, 7, 8), while K(+) situation was completely opposite with them (Figs. 3, 4). At the same time, the total ion content and composition inside the leaves remained more or less constant (Fig. 8).