Effects Of NaCl With Different Concentration On Morphological Structure In Vegetative Organs Of Suaeda Salsa

Plant responses to salt via a complex mechanism including many kinds of biochemical events, thus the plant displays singular structure during its adaptation to salt stress. The aim of the present investigation was to shed light on the mechanism of salt tolerance in plants by studying the different microstructure and ultratructure of tissues and organs of suaeda salsa and relating the differences in response to salinity at different concentration. The main results are shown as follows:1 Under NaCl stress, the succulent degree of leaves was enhanced, which was showed by measurement of well-developed palisade tissues, water-storing parenchyma and thick epidermis layer made of big parenchyma cells.2 Leaflets from plants grown in the increasing salt concentrations (up to 200mM) became smaller and thicker, leading to the smaller ratio between superficial area and mesophyll tissue volume. In the same process, the cuticle became thickness significantly increased while stomata became less in number and smaller in area.3 Growth of stellar tissue increased with the stimulation of NaCl, especially the xylem and its vessel.4 Comparing with control, bigger starch grains and more chloroplast were commonly found in the leaves of the salined surrounding. In addition, at the ultrastructure scale , there are evident differences in chloroplast. In lower salinity (50,100mM), the lamellae of stoma and grana in some chloroplast expanded lightly; the boundary of the chloroplast was dim. In higher salinity (200,400mM) the lamellae expanded remarkably, the membrane of the chloroplast was broken, some crystallinitywas found in some chloroplast. There is also some compound vesicular structure in the mesophyll cells under salt stress.The results were discussed with regard to the mechanism by which the vesicular structure was produced.5 Layer number of cortical cells in stem wasn't changed evidently, however the ratio between cortical thickness and stem increased as well as the ratio between vascular cylinder and stem, up the gradient of NaCl concentration.6 Stem DM of suaeda salsa remarkably decreased with increasing NaCl concentration, so did the vessel DM of xylem in the stem.7 Within the range of 0-200mM NaCl concentration, the ratio between cortical thickness and root got lower; the growth of stele was stimulated; vessel DM decreased evidently .In stele , conducting tissue was reduced while the growth of pith was stimulated.8 The pith made of small parenchyma cells was long - oval, However the pith looked like a cross which devided the preliminary xylem into four parts was made of larger parenchyma cells.9 There are well-developed aerenchyma in suaeda salsa, including large sub -stomatal chambers and intercellular spaces in palisade layer, spaces produced by lysigenous breakdown of cortical cells in stem and roots.