Abstract:

Gas exchange and chlorophyll fluorescence in Ficus microcarpa and Areca triandra in greenhouse before and after shading in summer were explored. Data revealed that A. triandra was sensitive to higher temperature and strong irradiance, however F. microcarpa was contrary. Maximal PSⅡ photochemical efficiency was down-regulated distinctly in A. triandra at noon under higher irradiance and temperature before shading, whereas, only slight down-regulation occurred in F. microcarpa. After shading, the down regulation was alleviated. Unfortunately, daily average photosynthetic rate in A.triandra and F. microcarpa decreased to some extent after shading; the former reduced smaller than the latter. Thus, it can be deduced that shading in summer could reduce the down-regulation of the maximum PSⅡ photochemical efficiency, but shading also resulted in the decrease of daily average photosynthetic rate, especially to light-preferring plants.

Key words: Ficus microcarpa, Areca triandra, Greenhouse, Shading, High temperature, High irradiance, Photosynthesis