不同叶形树种幼苗叶片气体交换对模拟风胁迫的响应

Wind damage hurts the physiological activity, such as leaf gas exchange, and growth badly for plants, which influences the vegetation recovery and re-construction in coastal area. Leaf shape, like leaf margin, width, length, area, etc., plays vital role on plant response and adaption to wind loading. In this program, 4 tree species seedlings, with high wind-resistant ability and different leaf shapes in coastal area, are introduced to be studied for 3 years. They are located in phytotrons with relative homogeneous environment (temperature, humunity and CO2 concentration) and different wind speed treatments simulated from Wind Tunnel Simulation Experiment. For these tree seedlings, leaf boundary layer conductance (gl), photosynthesis and water utilization would be monitored, and the differences of leaf gas exchange response to wind loading would be explored. The photosynthetic enzymes activity, chlorophyll fluorescence, osmotic adjustment ability and leaf anatomical and ultra stucture would be determined, and the adaption mechanism of plant leaf gas exchange to wind loading would be clarified. The biomass allocation in leaf, stem and root would be surveyed and the adaption of photosynthetic products to wind loading would be uncovered. These results would be helpful for clarifying the function of leaf shape on leaf gas exchange response and adaption to wind loading. This would be important for deeply understanding relatioship between plant and wind, also provide basis guideline for tree species selection and arrangement of coastal shelter forest systems.

风害对植物生理活动(气体交换)和生长发育产生巨大危害，严重影响了沿海地区植被恢复与重建。叶片叶缘、长度、宽度和面积等形态特征在植物适应风胁迫中具有举足轻重的作用。本项目以沿海地区抗风性能较好的4种不同叶形树种幼苗为研究对象，采用人工气候室控制环境因子，利用风洞模拟设备控制不同风速处理，研究各树种叶片边界层导度、光合作用和水分利用的变化规律，揭示不同叶形树种叶片气体交换对风胁迫的响应差异；研究各树种叶片光合关键酶活性、叶绿素荧光参数、渗透调节物质和叶片结构的变化规律，揭示不同叶形树种叶片气体交换对风胁迫的适应调节机制；研究各树种生物量在器官间的分配规律并初步阐明不同叶形树种光合产物分配对风胁迫的适应差异。通过以上研究，在叶片水平上阐明叶形在植物叶片气体交换对风胁迫的响应和适应中的作用，不仅对认知植物与风的关系具有重要的科学意义，同时对沿海防护林体系树种选择和种间配置也具有重要的现实指导意义。

以不同叶形8种栎树为研究对象，模拟风胁迫，（1）系统测定了风胁迫下叶片净光合速率、气孔导度、叶绿素荧光、碳水化合物含量等生理特征，探明了不同叶形树种气体交换特征对风胁迫的响应规律及其生理生态学机制，发现风胁迫限制了阔叶树种麻栎叶片的光合作用，气孔限制和光系统电子传递速率及光化学效率的降低是其主要原因；风胁迫显著降低了裂叶阔叶树种的光合能力，光系统电子传递速率及光化学效率的降低和光合产物负反馈是其主导因子；而风胁迫对披针叶形树种光合作用的影响不大；同时，风胁迫下光合产物会更多的分配给纤维素、木质素等结构性碳水化合物；此外，还发现风胁迫不会改变叶片氮磷比值、氮磷间的相关性和化学计量特征与叶形特征的相关性，验证了化学计量学内稳性理论和叶片经济型谱理论。（2）通过测定树木各器官的形态、生长量及生物量等形态学特征，阐明了树木形态学特征对风胁迫的响应规律，发现风胁迫下阔叶树种麻栎生长受到抑制，生长量显著下降，其他裂叶阔叶和披针叶树种可以通过增加叶片厚度、地径和根系生物量的分配比例和降低高度等形态特征的改变来适应风胁迫；同时，还揭示了叶片分形指数与栎树抗风能力具有显著相关性，发现叶片分形指数大的树种其抗风能力较强。（3）通过测定树木生物力学特征，探明了披针叶树种和部分裂叶阔叶树种可以通过增加茎干的抗弯强度来适应风胁迫。综合8种栎树生理学、形态学和生物力学对风胁迫的响应与适应特征，发现栎树抗风能力与叶形存在较大的相关性，披针叶形栎树的抗风能力最佳，其次是裂叶阔叶树种，阔叶树种最差，这不仅丰富了我们对树木与风关系的认知，同时为防风林建设树种选择提供了科学依据。