盐胁迫下木榄幼苗叶片的解剖学变化

Leaf Anatomical Changes of Bruguiera gymnorrhiza Seedlings under Salt Stress

摘要:

对梯度盐度下木榄(Bruguiera gymnorrhiza)幼苗叶解剖特征进行观察，并分析木榄适应盐胁迫的形态学变化特点以及盐胁迫对植物生长的影响。在0‰～50‰盐度范围内，木榄胚轴均能正常萌发，但幼苗高度、鲜重以及叶面积与培养盐度之间存在着明显的负相关。随着盐度的增加，木榄叶的上(下)角质层和上(下)表皮层增厚，单宁细胞密度增大，上(下)内皮层变薄，叶肉细胞的胞间隙缩小；栅栏组织厚度因细胞的长度和宽度减小而变薄，而海绵组织厚度与培养盐度之间无明显的相关性，栅栏组织/海绵组织的比率下降。扫描电镜下栅栏组织细胞中的叶绿体数量和形态未见明显的变化，但叶绿体在细胞中的位置发生了改变。因此，盐胁迫下叶片栅栏组织厚度的下降、海绵组织中胞间隙的减少以及叶肉细胞中叶绿体的分布变化可能是导致植物光合效率下降和幼苗生长受阻的重要原因。

Abstract:

The leaf anatomical changes of Bruguiera gymnorrhiza seedling under gradient salinities were observed, and the effects of salt stress on plant growth were analysed. The hypocotyl of B. gymnorrhiza could germinated under the salinities from 0‰ to 50‰. However, the plant height, fresh weight and leaf area had negative correlation with salinities. With increment of salinity, the thickness of upper and lower cuticle, upper and lower epidermis, and the densities of tannin cell increased, but the thickness of upper and lower endodermis, the intercellular spaces of spongy tissue of leaves decreased. The thickness of palisade tissue decreased, and that of spongy tissue had no relation with salinity, the ratio of the thickness of palisade tissue to spongy tissue decreased with increasing salinity. With increasing of salinity, there were no obvious difference in quantity and shape of chloroplast under SEM, but their location in palisade cells occurred change. All these changes made seedlings photosynthesis inhibited and growth stunted.