海水水淹下海滨木槿和蜡杨梅幼苗叶片的光合作用及其影响因子研究

Photosynthesis of Leaves of Hibiscus hamabo and Myrica cerifera Seedlings and Its Influence Factors under Seawater-logging

滩涂消浪林是中国沿海防护林体系的前沿阵地，在防浪促淤、保岸护堤和防御海洋自然灾害等方面具有重要的作用。以中亚热带泥质海岸的两种消浪树种海滨木槿（Hibiscus hamabo）和蜡杨梅（Myrica cerifera）一年生幼苗为实验材料，根据半日潮滩涂的淹水时间和淹水深度，设计5种实验处理，即在每个半日潮中，两个树种的平均淹水时间和淹水深度分别为1h和15cm（处理1）、2h和25cm（处理2）、3h和35cm（处理3）、4h和45cm（处理4）以及无水淹的对照处理（用淡水正常浇灌）。在模拟海水水淹胁迫下的70d中，研究两树种幼苗向阳面叶片的光合作用日变化及其与叶片其他生理生态因子的关系，揭示其主要影响因子。结果表明，各处理下，海滨木槿幼苗叶片净光合速率（Pn）日变化（6：00-18：00）曲线为单峰曲线；在水深较浅、时间较短的水淹处理下，海滨木槿幼苗叶片Pn主要受光合有效辐射（PAR）影响，在水深较深、时间较长的水淹处理下，则主要受叶片气孔导度（Gs）和胞间CO2浓度（Ci）的影响；在水淹初、中期，蜡杨梅幼苗叶片Pn日变化曲线为双峰曲线，但在水淹后期，其为单峰曲线；在水深较浅、时间较短的水淹处理下，蜡杨梅幼苗叶片Pn主要受PAR和G影响，而在水深较深、时间较长的水淹处理下，其主要受Ci和饱和水蒸汽压亏缺影响。

Wave-breaking forest, as the foreland of coastal shelter forest systems, plays vital importance in breaking wave, protecting bank and recovring natural disaster from ocean. Hibiscus hamabo and Myrica cer- ifera are dominant tree species in wave-breaking forest in sub-tropical muddy coast. They were introduced to study the photosynthesis diunal dynamic, and the relationships between photosynthesis and leaf ecophysiologi- cal factors under simulating tide water-logging. The net photosynthesis rate of leaves of Hibiscus hamabo in- creased firstly, and then decreased with the increasing of seawater-logging stress. The diunal dynamic of the net photosynthesis rate of Hibiscus hamabo leaves showed a unimodal curve. The net photosynthesis rate of Hi- biscus hamabo leaves was regulated by photosynthetic active radiation under slight stress, while by stomatal condunctance and intercellular CO2 concentration under heavy stress. The net photosynthesis rate of Myrica cerifera leaves decreased with the increasing of the stress. The diunal dynamic of the net photosynthesis rate ofMyrica cerifera leaves showed a double-peak curve, while a unimodal patern was found in the senventi- eth days. The net photosynthesis rate ofMyrica cerifera leaves was regulated by photosynthetic active radiation and stomatal condunctance under slight stress, while by intercellular CO2 concentration and vapor pressure deficit under heavy stress.