where s is the pore radius, N is the number of pores and L is the
length of the circular cross section of pores. From Eqs. (2)–(8), gs
is strongly affected by the diffusion coefficient of CO2 (D). D is
expressed by Eq. (2), which indicates that D increases in proportion
to the square of the temperature (T) and decreases with increasing
pressure (P). Therefore, from Eqs. (2)–(8), it is clear that gs decreases
in proportion to the increase in pressure (P).
Moreover, the rate of net photosynthesis strongly depends
on mesophyll conductance explained that, when the chloroplast
surface area exposed to an intercellular air space is large,
the rate of net photosynthesis increases. This is because the diffusion
coefficient of CO2 in the liquid phase is about 10,000 times
slower in water than in air, and thus it is essential for a rapid CO2
exchange to increase the surface area available for gas exchange.
Eq. (9) expresses the diffusion coefficient of CO2 in the liquid phase
(D1). In this study, since the temperature is kept constant and the
cell sap was an incompressible fluid, it can be easily understood
from Eq. (9) that the CO2 coefficient of diffusion in the liquid phase
(D1) is not affected by total pressure;