A Continuous Canopy Photosynthesis Measurement System for CAM Plants

Portable photosynthetic measurement based leaf gas exchange is one tool of most important photosynthesis research techniques. However, it is not suitable for CAM plants because of the main CO₂ absorption in dark period and CO₂ assimilation in photoperiod. Some facultative CAM plants always show certain amount of CO₂ uptake in photoperiod, therefore lead to incorrect determination of the gas exchange characteristics. Therefore, a canopy photosynthesis continuous measurement system based on two leaf canopy chambers was developed and tested for obligate CAM plant (Kalanchoe daigremontiana), facultative CAM plant (Dendrobium officinale), C3 plant (Fragaria ananassa Duchesn), and C4 plant (Zea mays) under artificial and natural lightings. The results show that the canopy photosynthesis continuous measurement is not only suitable for quantitative evaluation of gas exchange characteristics in CAM plants, but also suitable in C3 and C4 plants with weak photosynthetic capacity.