Effects of air current speed on gas exchange in plant leaves and plant canopies.
To obtain basic data on adequate air circulation to enhance plant growth in a closed plant culture system in a controlled ecological life support system (CELSS), an investigation was made of the effects of the air current speed ranging from 0.01 to 1.0 m s-1 on photosynthesis and transpiration in sweetpotato leaves and photosynthesis in tomato seedlings canopies. The gas exchange rates in leaves and canopies were determined by using a chamber method with an infrared gas analyzer. The net photosynthetic rate and the transpiration rate increased significantly as the air current speeds increased from 0.01 to 0.2 m s-1. The transpiration rate increased gradually at air current speeds ranging from 0.2 to 1.0 m s-1 while the net photosynthetic rate was almost constant at air current speeds ranging from 0.5 to 1.0 m s-1. The increase in the net photosynthetic and transpiration rates were strongly dependent on decreased boundary-layer resistances against gas diffusion. The net photosynthetic rate of the plant canopy was doubled by an increased air current speed from 0.1 to 1.0 m s-1 above the plant canopy. The results demonstrate the importance of air movement around plants for enhancing the gas exchange in the leaf, especially in plant canopies in the CELSS.
Kitaya
Y
Y
Graduate School of Agriculture and Biological Sciences, Osaka Prefecture University, Osaka, Japan.
Tsuruyama
J
J
Shibuya
T
T
Yoshida
M
M
Kiyota
M
M
D000389:Air Conditioning; D000392:Air Movements; D018504:Ecological Systems, Closed; D027723:Ipomoea batatas / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D008021:Life Support Systems; D018551:Solanum lycopersicum / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology*