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摘要：采用石蜡切片法，在光学显微镜下观察三七景天（Sedum aizoon）根茎叶的解剖结构。结果表明：根由表皮、周皮、皮层和文管柱组成，周皮较厚，皮层约占横切面半径的4/5。茎由表皮、皮层和文管柱组成，皮层和文管柱的髓部由大量较大薄壁细胞组成，液泡比较发达。叶为稍肥厚的等面叶，上下表皮具不等型气孔器，上表皮气孔器少，叶肉由大量的薄壁细胞组成。在根、茎、叶中均观察到淀粉粒。景天三七根周皮较厚，叶的上表皮气孔器少，根茎叶中均具有大量储水的薄壁细胞，这些特征与其抗旱性有关。同时，在根茎叶中均观察到被染成红色的异细胞，可能也与抗旱性有关，但具体结构功能还有待研究。50586
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毕业论文关键词：景天三七；营养器官；解剖结构；抗旱性
Study on Anatomical Structure of Vegetative Organs of Sedum aizoon
Abstract: This paper discusses the anatomical structures of vegetative organs, which includes roots and stems and leaves of Sedum aizoon，with the light microscope by using paraffin method. The root of Sedum aizoon was composed of epidermis, periderm, cortex and vascular cylinder. The periderm was thick. Cortices account for about 4/5 of the transverse section radius. The stem was composed of epidermis, cortex and vascular cylinder. The cortex and pith of vascular cylinder were composed of a great number of large parenchyma cells and vacuole was developed. Sedum aizoon had little hypertrophic isobilateral leaves. The type of stomatal apparatus of upper and lower epidermis was anisocytic and upper epidermis had less stomatal apparatus. The mesophyll was composed of a large number of parenchyma cells. Starch grains were observed in roots, stems and leaves. The periderm of Sedum aizoon root was thick, upper epidermis had less stomatal apparatus and a large number of water storage parenchyma cells were in roots, stems and leaves, all these characteristics were related to the drought resistant. At the same time, idioblast dyed red was observed in roots, stems and leaves. The idioblast might be related to drought resistance, but the specific structure and function remained to be studied.
Key words: Sedum aizoon; Vegetative organs; Anatomical structure; Drought resistance.
目录
引言 1
1 材料与方法 2
1.1供试材料 2
1.2方法 2
2 结果与分析 2
2.1根 2
2.2茎 3
2.3叶 3
3 讨论 5
致谢 6
参考文献 6
引言
景天三七（Sedum aizoon）是景天科(Crassulaceae)景天属(Sedum)的多年生肉质草本花卉，又名费菜、土三七、养心草等，喜欢温暖的气候，耐旱、耐寒，对土质要求不严，但以砂质土为好，扦插、分株均能繁殖。其株形丰满，叶色绿，花色艳丽，可布置成花坛、花镜或者成片栽植作为地被应用，可食用也具有医学价值[1]。
景天科植物无性繁殖力强，耐寒、耐旱，极易种植观赏，也是当前屋顶绿化的首选植物。因其不仅观赏价值高，也具食用和较高的药用价值，所以人们对景天科植物的研究也颇多。在生理特性研究方面，高小燕[2]以景天属的几种植物作为实验材料进行人工控水干旱胁迫处理，通过测定生理指标和观察生长状况，综合评价得出松塔景天（Sedum Nicaeense）抗旱性最强。崔苗苗[3]研究了4种景天属植物在人工淹水胁迫下生理指标的变化，发现三七景天(Sedum aizoon)的耐涝性最强，垂盆草(Sedum sarmentosum)的耐涝性最弱。娄晓鸣等[4]通过测定相对电导率和水分含量2个抗寒生理指标，分析了10种景天属植物相对电导率和水分含量和抗旱性的关系，发现反曲景天(Sedum reflexum)抗寒性最强，八宝景天(Hylotelephium erythrostictum)抗寒性最弱。生物提取物方面，Jeong Hee Kimk等[5]从16种亚洲种景天植物里调查提取生物碱，结果只在7种植物里发现生物碱并进行分析，得出的结果支持了在景天科里生物碱被限制在‘Acre’谱系物种的假说。Wei Lin Li等[6]从景天三七植物中研究提取出两种新的异黄酮衍生物，通过光谱分析基础阐明其结构并测定提取物的抗氧化活性。组织培养方面，李莺等[7]把景天三七的茎段和叶片作为外植体，进行组织培养和植株再生实验，结果显示试管苗在大量元素减半的MS培养基上可直接诱导生根，生根率为100%。张莹等[8]以三七景天（Sedum aizoon）嫩叶作为外植体，进行离体快繁研究，分别表明出了愈伤组织诱导、芽诱导和芽增殖的最佳培养基成分。园林应用方面，涂爱萍[9]研究了景天作为屋顶绿化植物材料的可行适应性，通过测试耐寒耐阴性等，表明测试的景天属植物能适应当地气候，在园林中可加以应用。王国伟[10]根据景天三七的应用特点，说明了其在公路绿化中的应用。