Performance of Light Sources for Plants under Altered Gravity Conditions in Parabolic Airplane Flights

Abstract

Performances of light sources, a halogen lamp, a fluorescent lamp and light emitting diodes (LEDs), commonly used for plant culture were examined under altered gravity conditions created during parabolic airplane flights. The surface temperatures of the light sources, irradiances, photosynthetic photon flux densities (PPFDs) and spectral distributions of radiation from the light sources were measured at the gravity levels of 0.01, 1.0 and 1.8 G for 20 s each during parabolic airplane flights. As a result, the surface temperature of the halogen lamp bulb increased most rapidly and the irradiance increased most remarkably among the three light sources at 0.01 G. On the contrary, the surface temperatures and light intensities of LEDs were most stable followed by the florescent lamp with gravity change. These characteristics of LEDs would be suitable for plant experiments and plant culture in space. Keyword(s): LED, light, microgravity, wavelength