石斛属植物光合碳同化过程对环境变化的生理响应机制

The rare and endangered Dendrobium species have become important horticultural species with great potential to be explored in protected cultivation in the world, and its related research has increased rapidly in the last decade. Dendrobium plants have varying degrees of CAM photosynthetic characteristics, which varies with species and environment. The unique photosynthetic characteristics result in extremely slow growth and the cultivation techniques under controlled environment for Dendrobium plants are different from those of conventional horticulture crops. The commonly used methodology for measuring photosynthesis on a single leaf using the portable photosynthesis measurement device cannot accurately determine the true CO2 assimilation rate due to the fact of non-uniform stomatal closure, and the chlorophyll fluorescence measurement is also limited by dark adaptation. In this project, the CO2 exchange rates of D. offcinale, D. nobile, D. primulinum, and D. chrysotoxum will be measured continuously on a whole plant and the electron transport of PSⅡ and PSI will be determined based on steady-state chlorophyll fluorescence under light adaptation in order to understand the photosynthetic carbon assimilation characteristics. The effects of environmental conditions on photosynthesis pathways adjustion of above Dendrobium plants and its physiological response mechanism will be determined through quanitificaiton of electron transport, CO2 exchange, stomatal movement, and reversible enzyme adjustment. Furthermore, the universal photosynthetic characteristics with concomitance and shift of C3/CAM photosynthetic pathways in Dendrobium plants will be verified and used to understand the environmental regulation for improving the light use efficiency and photosynthetic efficiency through regular monitoring in light energy conversion and quantum efficiency under artificial lighting. The above research is in order to play the photosynthetic ability and promote the growth and development of Dendrobium plants, which provides theoretical basis and measurement techniques for Dendrobium cultivation and photosynthesis study of CAM plants.

珍稀濒危石斛属植物已成为全球最具发展潜力的设施园艺栽培种类，相关研究在近10年来快速增长。由于其光合作用依种群差异和环境变化表现出不同程度的CAM光合特征，故生长极其缓慢,人工栽培显著不同于常规园艺作物。现有石斛光合研究几乎都基于叶片气体交换和叶绿素荧光技术，未能反映其气孔不均匀开闭的影响并受到暗适应的束缚。本课题基于连续气体交换和稳态叶绿素荧光测量掌握铁皮石斛、金钗石斛、报春石斛、鼓槌石斛光合碳同化过程的气体交换特征和光适应下PSⅡ和PSⅠ的电子传递特性，从电子传递、气体交换、气孔运动、和酶活性调节等层面揭示石斛属植物的C3/CAM光合途径共存的特性，及其光合途径随环境变化而可逆调节的生理响应机制。进一步利用环境调节从光能转化和量子效率的角度提高人工光下石斛光能利用效率和光合效率，从而促进其光合能力发挥和生长发育，为石斛属植物人工栽培与CAM植物光合研究提供理论依据和实践指导。

珍稀濒危石斛属植物已成为全球最具发展潜力的设施园艺栽培种类，由于其光合作用依种群差异和环境变化表现出不同程度的CAM光合特征，故生长极其缓慢，期人工栽培方法显著不同于常规园艺作物。现有石斛属植物研究几乎都基于常规的适于C3植物而开发的叶片气体交换和叶绿素荧光技术，不能反映CAM植物气孔不均匀开闭的影响。本课题基于连续气体交换和稳态叶绿素荧光测量掌握铁皮石斛、金钗石斛、报春石斛、鼓槌石斛光合碳同化过程的气体交换特征和光适应下PSⅡ和PSⅠ的电子传递特性，从电子传递、气体交换、气孔运动等层面揭示了石斛属植物的C3/CAM光合途径共存的特性，及其光合途径随光照周期和水分胁迫而可逆调节的生理响应机制。该研究利用环境调控技术提高石斛属植物的光能转化效率和量子转化效率，从而开发出一种水培LED立体高效栽培新方法，可以提高石斛属植物在人工光下的光能利用效率和光合效率，有效地促进其生长发育和品质调控，为石斛属植物人工栽培与CAM植物光合研究提供理论依据和技术支持。