Stomatal Resistance of Rice Leaves as Influenced by Radiation Intensity and Air Humidity

Abstract

This paper describes results of field experiments of relationships between meteorological conditions and stomatal resistance of rice leaves. The magnitude of stomatal resistance of rice leaves was measured by a porometer at important three developmental stages of rice plants. Stomatal resistance (r_s) changed very clearly throughout sunny days in relation to diurnal variation in solar radiation intensity (S_t) and leaf air vapor concentration deficit (HD).
Stomatal resistance of the adaxial surface of rice leaves was found to be the same to that of the abaxial surface in the magnitude, indicating that the water vapor fluxes at the both surfaces of rice leaves are equal with each other. The dependence of non-dimensional stomatal resistance [r_s/r_m·k(HD)²] on solar radiation intensity (S_t) was well approximated by a hyperbolic function. The relationship between HD and [r_s/r_m(1+S_{t, m}/S_t)] was expressed by a quadratic function of HD.