抄録
In the field conditions the leaf-blades of rice plants receives sunlight on its abaxial side as well as on its adaxial side. Therefore, the authors studied the relation between the light intensity and the amount of CO2 absorption on the abaxial side as well as the adaxial side of a sigle leaf to clarify the amount of carbon assimilation in each side respectively, using the attached flag-leaves of Norin No.25 and Kinmaze. 1) The amount of CO2 absorption on both sides of a leaf were increased respectively, increasing the light intensity (artificial incandescent light) on the abaxial side and giving no light on the adaxial side. The amount of CO2 absorption on the abaxial side attaind a maximum level at the light intensity of 0.6 cal/cm2/min., while that of adaxial side was still increasing. These facts mean that the abaxial side is already saturated but the adaxial side in not saturated with light. The abaxial side in always much larger than the adaxial side as far as the amount of CO2 absorption is concerned, and vice versa. 2) The amount of CO2 absorption on both sides are always equal when both adaxial and abaxial side are illuminated at the same light intensity. 3) If the total light intensity on both sides were equel, total amount of CO2 absorption on a single leaf might be the largest when the light was differently projected, and might be always the smallest when the light was projected only from one side.
