ENERGY DISTRIBUTION OF THE RICE PLANT CANOPY

Fundamental studies on evapotranspiration in paddy fields (I)

Abstract

This series of studies is aimed at clarifying the mechanism of evapotranspiration from rice-planted paddy fields. Paddy fields are unique among crop fields because they are ponded throughout the rice growing season. In this report, the authers present the micrometeorology and water budget observation results regarding paddy fields, and discuss the energy distribution of the rice plant canopy. The results show that when rice plants sufficiently covered the water surface, the canopy was able to be maintained at relatively low temperatures and high humidity compared with that of the ambient atmosphere. This condition caused the sensible heat flux from both the upper atmosphere and the water surface to go to the canopy. As a result, the evapotranspiration exceeded the net radiation which was supplied to the canopy.