群落光合成

In our previous paper it was reported that the rice plant population had higher utilization and conversion efficiencies than the soybean plant population, In this paper, these results are studied from the viewpoint of the differences between rice and soybean stands in inclination angle of a leaf, and light intensity on both surface of a leaf within a canopy. Azimuth angles of the normal on the upper surface of rice leaves were distributed uniformly in all direction, but those of soybean leaves were mostly oriented to the south at noon and to the west in late afternoon. The inclination angles of rice leaves to the horizontal were large at upper layers and it decreased gradually to the lower layers within a stand. Though inclination angles of soybean leaves at the top layer were slightly larger, those at other layers were smaller. The light intensity incident on the upper surface of rice leaves was somewhat equal throughout the canopy but that of soybean leaves was divided into two groups of high and low intensity. Also, the lower surfaces of rice leaves had received more light energy than those of soybean. Since the photosynthetic rates of leaves with radiation on both surfaces were larger than those with radiation on the upper surface only, the photosynthesis of rice leaves favoured.