kept constant for 24 h with dry air (Fig. 3). On the other hand, the
pressure slowly decreased by 5% with wet air. This was because
some of the water vapor condensed in liquid. The temperature and
humidity in the chamber were kept constant for 24 h (Fig. 4).
In this study, the effects of elevated total pressure on the rates
of photosynthesis and respiration were investigated by measuring
the concentration of CO2 in the chamber. Note that CO2 dissolved
more easily in the liquid medium under elevated total pressure
than under atmospheric pressure. In this study, the original plant
support device was adapted to inhibit CO2 dissolution in the liquid
medium. It was fabricated from a silicon tube with an external
diameter (ϕ) of 8 mm, a wall thickness of 1 mm and a length of