Abstract
The effects of increasing ambient CO2 levels on the growth of developing Doritaenopsis plants in a greenhouse were studied for 840 days. Leaf area, dry weight, and content of total carbon and total nitrogen in dry matter were measured every three months, and the time course of the relative growth rate (RGR) was investigated. Leaf area and dry weight increased with increasing CO2 concentration from 438 ppm to 946 ppm in the atmosphere. In an initial grwoth stage when plants were transplanted from flasks to pots, RGR increased as the CO2 level increased. RGR during a later vegetative growth stage was not affected by the CO2 concentration, and its value was 0.006/day. The value of RGR was less than that of the other C3, C4, and CAM plants.
