兰科兜兰属和杓兰属植物叶片性状研究
关志洁
学位类型博士
导师管开云 ; 胡虹
2010-01
学位授予单位中国科学院研究生院
学位专业植物学
摘要兜兰属和杓兰属亲缘关系密切,同属杓兰亚科,但在地理分布、生活型以及叶片特性等方面存在众多差异。本文通过对兜兰属和杓兰属植物的叶片形态和解剖结构、叶寿命、比叶重、光合能力、资源利用效率、叶片构建成本和维持成本以及土壤、气候等环境因子进行研究和比较,试图了解两类植物的叶片性状和生理生态适应性的关系,并探讨由此引发的生态学和进化意义。研究发现:1、与杓兰相比,兜兰的叶片在形态和结构上具有旱生的特点,这表现为较厚的叶片、巨大的上表皮细胞、较厚的表皮角质层、叶肉组织的分化、叶片中粘性物质的存在、强支撑力的叶片主脉、较低的气孔面积/叶片面积比值、下陷的气孔和特殊的气孔构造。而杓兰叶片的形态结构特点与兜兰相反。兜兰和杓兰的叶片形态结构均体现了与环境适应性的统一。我们所研究的19种兜兰的保卫细胞中均不含叶绿体。2、不同叶龄杏黄兜兰叶片光合能力的变化顺序为叶龄1-2年﹥0-1年﹥2-4年,黄花杓兰为60天﹥30天﹥90天﹥120天。3、杏黄兜兰不同叶位叶片的光合能力主要受叶龄的影响,最顶端的四片叶子对植株光合同化物积累的贡献最大,第6片及以后的叶子不但对光合同化物的积累起不到促进作用还要耗费大量的营养,对植株养分起到负的贡献。4、杏黄兜兰光合速率的最大值出现在上午的10点钟,光合速率与气孔导度的变化趋势大致相同。较高的空气湿度对杏黄兜兰保持高的光合速率可能极为关键。5、黄花杓兰叶片的光合能力显著高于杏黄兜兰。杏黄兜兰低的叶片光合能力与低的叶片氮含量、磷含量和酶含量有关,杏黄兜兰极低的气孔导度和叶肉导度可能也大大限制了叶片的光合速率。另外兜兰低的光合能力还可能与保卫细胞叶绿体的缺失有一定关系。相比杓兰,兜兰更偏阴生。6、杓兰的短寿命叶与快速的碳固定和相对较快的生长有关;而兜兰的长寿命叶有助于植物体内养分驻留更长时间,以补偿兜兰低的光合生产能力。杓兰的短寿命叶具有高的光合速率和呼吸速率,光合速率随叶龄降低速率也快,而兜兰则与之相反。7、兜兰相比杓兰具有高的水分利用效率和低的光合氮利用效率。8、相比杓兰,兜兰叶片具有高的构建成本和长的偿还时间。综上所述,兜兰和杓兰的叶片结构和生理功能反映了它们对生境的适应。兜兰的叶片形态结构和生理功能的进化与适应喀斯特地区匮乏的水肥条件有关。杓兰的叶片性状是对水肥条件较好,但季节波动较大生境的适应。我们的结果为同源兰科植物在自然选择下的趋异进化提供了证据。
资助项目Paphiopedilum and Cypripedium are close relatives belonging to the subfamily Cypripedioideae. However, they undergo considerable divergence in the aspects of life forms, leaf traits and habitats. In present study, leaf morphologies and anatomical structures, leaf lifespans, leaf mass per area, photosynthetic capacities, nutrient use efficiencies, leaf construction costs, and maintenance costs were investigated to understand the relationship between leaf traits and ecophysiological adaptability of the two types of plants and explore the related ecological and evolutionary significances. The results suggest that:1. Compared with Cypripedium, Paphiopedilum was characterized by drought tolerance from its leaf anatomical structure including fleshy leaf, thicker surface cuticle, huge abaxial epidermis cells, differentiation of palisade and spongy mesophyll layers, the prominent of mucilaginous substances, supportable leaf main vein, lower total stoma area (%), sunken stomata and special stoma structure. Leaf morphologies and structures of Cypripedium were to the contrary of Paphiopedilum. Leaf morphologies and structures embodied the adaptation to the environment in both Paphiopedilum and Cypripedium. Our results also confirmed the previous observation that Paphiopedilum was the only genus that did not possess guard cell chloroplasts.2. The photosynthetic capacities of P. armeniacum leaves were different with different leaf ages. The highest photosynthetic capacity occurred in leaf age 1-2 years, followed by 1 year and 2-4 years. The highest photosynthetic capacity of C. flavum occurred in leaf age 60 days, followed by 30 days, 90 days and 120 days. 3. Photosynthetic capacities of different leaf positions were mainly affected by leaf ages in P. armeniacum. The four leaves lying on the top did the most accumulation of the assimilation products in the whole plant. The leaves of sequence number > 6 could use lots of photosynthates, but contributed little to the accumulation of biomass. 4. Photosynthetic rate of P. armeniacum decreased a little at the noon, and the highest photosynthetic rate was observed at 10:00h in the greenhouse. The variation of photosynthetic rate was in the same trend as stomatal conductance. Higher relative humidity seemed to be the key for higher photosynthetic rate in P. armeniacum. 5. The photosynthetic capacity of C. flavum was statistically larger than that of P. armeniacum. The lower leaf photosynthetic capacity of P. armeniacum was related to its lower leaf nitrogen concentration,leaf phosphorus concentration and enzyme activities. Meanwhile, the extremely lower stomatal conductance and internal mesophyll conductance might greatly limit the photosynthetic capacity of P. armeniacum. The lower stomatal conductance and photosynthetic rate of Paphiopedilum might partially caused by the lack of chloroplasts in the guard cell of Paphiopedilum. Compared with C. flavum, P. armeniacum was more fond of shade environment.6. The short longevity leaf of Cypripedium had bigger photosynthetic capacity and greater potential for fast growth. But the longer LL of Paphiopedilum enhanced nutrient conservation which could compensate its lower photosynthetic capacity. The short longevity leaf of Cypripedium usually had higher photosynthetic rate per unit leaf mass and dark respiration rate, and photosynthetic capacity decreased fast with leaf age. However, for Paphiopedilum, the situation was the opposite. 7. Compared with Cypripedium, Paphiopedilum had higher water use efficiency and lower photosynthetic nitrogen use efficiency. 8. The leaf of Paphiopedilum had higher leaf construction cost and longer repayment time than that of Cypripedium. The leaf structures and physiological functions of Paphiopedilum and Cypripedium reflected the adaptation to their habitats. The leaf morphological and physiological evolution of Paphiopedilum was related to water and resource-conserving traits in the karst habitat. The leaf traits of Cypripedium were the adaptation to the environment rich in water and nutrients but easy to change with seasons.Our results provided evidence of divergent evolution of congeneric orchids under natural selection.
语种中文
文献类型学位论文
条目标识符http://ir.kib.ac.cn/handle/151853/16086
专题昆明植物所硕博研究生毕业学位论文
推荐引用方式
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关志洁. 兰科兜兰属和杓兰属植物叶片性状研究[D]. 中国科学院研究生院,2010.
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