Steady-state Chlorophyll Fluorescence Measurement for Photosynthesis Research of CAM Plants

Chlorophyll fluorescence measurement is one of most important techniques in photosynthetic research related to plant physiological ecology and stress physiology. Because of special photosynthetic carbon assimilation pathway of CAM plants, the CO₂ uptake and the assimilation has certain time and the stomata movements always show non-uniform closure phenomenon. In order to store water better and reduce transpiration and thereby improving light and water use efficiencies, facultative CAM plants often show non-uniform stomata closure movement and C3 and CAM pathways switching to eliminate various environmental stress influences and adapt better the environment changes. However, chlorophyll fluorescence measurement based on saturation pulse fluorescence or OJIP rapid fluorescent in CAM plants may not take linkage evaluation in photosynthetic electron transport and carbon assimilation in PS II and PS I because of the dark adaptation. Therefore, a steady-state chlorophyll fluorescence measurement method with the theory and instrument under light adaptation is proposed to apply in photosynthesis research of CAM plants and the plants with non-uniform stomata closure.