Kitaya Y, Kawai M, Tsuruyama J, Takahashi H, Tani A, Goto E, Saito T, Kiyota M
Graduate School of Agriculture and Biological Sciences, Osaka Prefecture University, Gakuen-cho, Sakai, Osaka, Japan.
Plant Cell Environ. 2003 Apr;26(4):497-503. doi: 10.1046/j.1365-3040.2003.00980.x.
A fundamental study was conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long-term under microgravity conditions in space. To clarify the effects of gravity on heat exchange between plant leaves and the ambient air, surface temperatures of sweet potato and barley leaves and replica leaves made of wet paper and copper were evaluated at gravity levels of 0.01, 1.0, 1.5 and 2.0 g for 20 s each during parabolic aeroplane flights. Thermal images were captured using infrared thermography at an air temperature of 26 degrees C, a relative humidity of 18% and an irradiance of 260 W m-2. Mean leaf temperatures increased by 0.9-1.0 degrees C with decreasing gravity levels from 1.0 to 0.01 g and decreased by 0.5 degrees C with increasing gravity levels from 1.0 to 2.0 g. The increase in leaf temperatures was at most 1.9 degrees C for sweet potato leaves over 20 s as gravity decreased from 1.0 to 0.01 g. The boundary layer conductance to sensible heat exchange decreased by 5% when the gravity decreased from 1.0 to 0.01 g at the air velocity of 0.2 m s-1. The decrease in the boundary layer conductance with decrease in the gravity levels was more significant in a lower air velocity. Heat exchange between leaves and the ambient air was more retarded at lower gravity levels because of less sensible and latent heat transfers with less heat convection.
开展了一项基础研究，以开发一种具备充足空气循环系统的设施，用于在太空微重力条件下长期培育健康植物。为了阐明重力对植物叶片与周围空气之间热交换的影响，在抛物线飞机飞行过程中，分别在0.01、1.0、1.5和2.0 g的重力水平下，对甘薯和大麦叶片以及由湿纸和铜制成的仿造叶片的表面温度进行了20秒的评估。在空气温度为26摄氏度、相对湿度为18%、辐照度为260 W m-2的条件下，使用红外热成像技术拍摄热图像。随着重力水平从1.0降至0.01 g，平均叶片温度升高了0.9 - 1.0摄氏度；随着重力水平从1.0升至2.0 g，平均叶片温度降低了0.5摄氏度。当重力从1.0降至0.01 g时，甘薯叶片在20秒内的温度升高最多为1.9摄氏度。在空气流速为0.2 m s-1时，当重力从1.0降至0.01 g时，边界层显热交换传导率降低了5%。在较低的空气流速下，随着重力水平降低，边界层传导率的降低更为显著。由于较低重力水平下显热和潜热传递减少，热对流减少，叶片与周围空气之间的热交换受到的阻碍更大。
