Principles of leaf hydraulic design

叶片水力设计原理

• 批准号: 0517071
• 负责人: Maciej Zwieniecki
• 金额: $ 24.49万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2008-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0517071&HistoricalAwards=false
• 关键词: Principles; leaf; hydraulic; design

Leaves are complex structures that balance CO2 uptake and water loss. This work addresses the micro-hydrology of leaves, focusing on two goals: (1) understand the biophysics of water movement within leaves and (2) determine the physiological significance of separating photosynthetic cells from the high demands for water imposed by the transpiration. Earlier studies show that leaves consist of two hydraulically isolated water pools linked to the water supply path (xylem) via low and high resistance pathways. How these hydraulically distinct pools of water are related to the structure and physiology of leaves is not known. One hypothesis is that photosynthetic cells are hydraulically isolated from the transpiration stream and that this isolation is under biological control. The separation of the transpirational path from the photosynthetic tissue may protect chlorophyll bearing cells from sudden changes in micro-environmental conditions. The goals are to understand the principles of leaf hydraulic design, explore the biological basis for hydraulic compartmentalization, and determine the physiological significance of the internal hydraulic architecture of leaves. The research will include analysis of rehydration kinetics of leaves to quantify the relative sizes of the two compartments. In addition, cell pressure probe measurements will determine hydraulic linkages between different "compartments" as well as the identity of these pools. These methods will be combined with experimental treatments (temperature, metabolic inhibitors) and morphological studies to resolve the nature of the hydraulic separation of the two water pools. Mathematical modeling will be used to explore the ways in which compartmentalization impacts leaf performance. Stomatal behavior and xylem vulnerability will be measured to determine whether a fast hydraulic compartment exists that allows plants to operate close to their cavitation limit. The research will fundamentally alter the understanding of the structure and physiology of leaves. In addition, the research will improve understanding of plant diversity by extending the studies of foliar water compartmentalization across a wide range of taxa representing diverse evolutionary lineages, growth forms, and ecologies. Activities leading to broader impacts are designed to extend ideas from this research to a broader audience. Such activities include: (1) mentoring and supporting younger scientists at all levels and (2) outreach activities directed to the public. Efforts will include creation and maintenance of a webpage on leaf hydraulics that is linked to the Arnold Arboretum website. The website will explain the goals and current findings of this research and will outline activities relevant to this topic for school classes visiting the Arboretum. In addition this research will be popularized via public lectures at The Arnold Arboretum as a part of their ongoing public program and an article in Arnoldia magazine.

叶子是平衡CO2吸收和水分损失的复杂结构。 这项工作解决了叶片的微水文，重点是两个目标：（1）了解水分运动的生物物理学在叶片和（2）确定分离光合细胞的生理意义的高需求的水分所施加的蒸腾。早期的研究表明，叶片由两个水力隔离的水池组成，通过低阻力和高阻力途径连接到供水路径（木质部）。这些不同水力的水池与叶子的结构和生理学是如何联系在一起的还不清楚。有一种假说认为光合作用细胞与蒸腾流在水力上是隔绝的，这种隔绝是在生物控制之下的。蒸腾路径与光合组织的分离可以保护叶绿素承载细胞免受微环境条件的突然变化。目的是了解叶片水力设计的原则，探索水力分区的生物学基础，并确定叶片内部水力结构的生理意义。该研究将包括叶片的再水化动力学分析，以量化两个隔室的相对大小。 此外，细胞压力探针测量将确定不同“隔间”之间的水力联系以及这些池的身份。这些方法将与实验处理（温度，代谢抑制剂）和形态学研究相结合，以解决两个水池的水力分离的性质。数学建模将被用来探索区室化影响叶性能的方式。 气孔行为和木质部的脆弱性将被测量，以确定是否存在一个快速的液压室，允许植物接近其空化极限操作。这项研究将从根本上改变人们对叶子结构和生理的认识。 此外，该研究将通过扩展对代表不同进化谱系、生长形式和生态的广泛类群的叶面水区室化的研究来提高对植物多样性的理解。 产生更广泛影响的活动旨在将本研究的想法推广到更广泛的受众。 这些活动包括：（1）在各级指导和支持年轻科学家;（2）面向公众的外联活动。 工作将包括创建和维护一个与阿诺德植物园网站链接的叶片水力学网页。该网站将解释这项研究的目标和目前的结果，并将概述与这一主题有关的活动，供学校班级参观植物园。此外，这项研究将通过在阿诺德植物园的公开讲座推广，作为他们正在进行的公共计划的一部分，并在Arnoldia杂志上发表文章。