厚壁毛竹与毛竹叶表皮微形态特征比较研究

Micromorphological study on leaf epidermis of Phyllostachys edulis‘Pachyloen'and Phyllostachys edulis

关键词:  厚壁毛竹  毛竹  营养叶  表皮

Key words:  Phyllostachys edulis ‘Pachyloen'  Phyllostachys edulis  trophophyll  epidermis

摘要:

利用扫描电镜技术,对厚壁毛竹(Phyllostachys edulis‘Pachyloen')与毛竹(Phyllostachys edulis)营养叶的表皮微形态进行对比研究,结果表明两竹种叶表皮微形结构组成基本相似,均以下表皮结构较为丰富,分布有乳突,微毛,刺毛,硅细胞,气孔器等结构。两竹种叶表皮主要区别在于厚壁毛竹的气孔轴向长度大于毛竹,而气孔密度要低于毛竹,但差异不显著。而两竹种叶的乳突密度相差不大,在不同年龄的竹叶间也无明显变化规律。同一竹种不同竹龄间竹叶表皮气孔密度和气孔轴向长度却有着显著的差异。1年生厚壁毛竹的气孔密度显著高于2年生竹和5年生竹,气孔轴向长度呈现出“V”字形变化规律。毛竹的气孔密度也出现类似的变化规律,但5年生竹叶的气孔密度最大,气孔轴向长度则表现出随秆龄增大而逐渐增长的趋势,这与竹材物质形成积累规律相一致。通过对比研究厚壁毛竹和毛竹叶表皮形态结构特征,两竹种叶表皮微形态特征相似与两竹种系统分类上的地位相近是一致的,同时对厚壁毛竹厚壁性状形成的结构基础进行探讨,为进一步揭示厚壁形成的机理提供了理论依据。

Abstract:

Micromorphological characteristics of leaf epidermis of Phyllostachys edulis ‘Pachyloen' and Phyllostachys edulis were observed by scanning electron microscope. The results indicated that the micromorphological characteristics of leaf epidermis of two bamboo species were similar with relatively simple adaxial epidermis only composed of long cell,short cell and bulliform cell. While the abaxial epidermises were complicated,which had papilla,microhair,prickle,silica and stomata. There were three papilla forms:round,granular and rod papillae. Round papilla was the largest distributing in longitudinal rows. The granular papillae were the smallest widely distributing in the abaxial epidermises. And the rod papillae were located surrounding the stomata. The microhairs were sparse and composed of two cells with the apical cell withered,possibly because of the thin cell walls and the top cell,whose cell wall was thick. The stomata were composed of subsidiary cells and kidney-shaped guard cells,and distributed among long cells between the veins of the abaxial epidermises with four papillae overarhing them. Bristles with sharp tops were widely distributed in the abaxial epidermises and the cell walls were thin. The bristles were located parallelly with the epidermis and surrounded by four granular papillae. Silicon cells and cork cells were often located in pairs among the long cells in the epidermis. And they were slightly sunken,round or nearly round. No silicon cell and cork cell distributed between veins. The remarkable differences between leaf epidermis of Phyllostachys edulis ‘Pachyloen' and Phyllostachys edulis were the length and density of stomata on the abaxial epidermis:the stomata of P. edulis ‘Pachyloen' were longer than that of P. edulis except those of two-year-old ones,while its stomatal density was low. There was no significant difference of papilla density between both two bamboo species and different ages of the same species. While stomatal density and axial length change strikingly with aging. The stomatal density of one-year-old P. edulis ‘Pachyloen' was 609±25 per mm²,larger than those of the two-year-old and five-year-old bamboo. The axial length of the stomata of P. edulis ‘Pachyloen' changed as “V” with aging,that was the axial length of the stomata of two-year-old P. edulis ‘Pachyloen' was the smallest,(18.909±1.322)μm. The same rule was in the changes of stomatal density of P. edulis,while the largest was that of the five-year-old bamboo,and the stomatal axial length of P. edulis leaves become longer with aging. The results did accord with the development of the culm. The results of analysis of variance about the micromorphological characteristics of leaf epidermis of two bamboo species showed that there was no dramatic difference of papilla density,stomatal density and axial length of the stomata in the abaxial epidermises between the same ages of both two bamboo species(P>0.05). The similar characteristics of leaf epidermis also showed that the systematic relationship of two bamboo species. This study is important to elucidate the structural foundation of forming thicker culm,to make an intensive study and good use of the new bamboo variety,and will provide theoretical basis for raising the bamboo biomass.