Abstract
Carbon dioxide (CO2) absorption rates of Phalaenopsis spp. plants were measured under different duration of light/dark periods from 2/22 to 22/2 h/d. Typical photosynthetic pattern of CAM plants was observed when light period was between 6 and 16 h/d. When light period was longer or shorter than the range, CO2 absorption during the dark period was decreased. The CAM type photosynthetic pattern was most obvious near 10 h/d light period. There was a linear relationship between daily light absorption and daily photosynthetic amount. As the light period became longer, amount of CO2 absorbed during the light period increased. Therefore, environmental management based on the assumption that Phalaenopsis plants absorb CO2 mainly at night would not be rational or profitable since large amount of CO2 is absorbed during the daytime.
