Studies on the Effect of Wind Speed on Photosynthesis

The measurements of photosynthesis of plant community were carried out at a paddy field of Dainakanoko reclained land near Lake Biwa from 1970 to 1972 by the aerodynamic method with the self recording instrument which was developed by the authors.The amount of gross photosynthesis of plant community increases largely not only with solar radiation but also with wind speed and the following relationship was obtained between the mean wind speed within plant layer and the photosynthesis.P=(const)Uav0.7-0.8where P: gross photosynthesis of plant community, Uav: mean wind speed within plant layer.This means that the structure of air flow in the boundary layer near leaf surface of rice plant is turbulent.Although canopy photosynthesis has been analyzed only by the absorption of light within the plant layer, present results indicate that the exchange process of carbon dioxide from the atmosphere to the leaves of plant community plays an important role on the photosynthesis of plant community under field conditions.