The Effect of LED Illumination at Night on Heading Time and Yield in Oryza sativa L. cv. Hinohikari

Light pollution due to outdoor lighting results in a delayed heading time and reduced yield in rice. We investigated the effect of light pollution by a method whereby rice grows in a paddy field exposed to three sources of outdoor illuminations: commercial LED illumination, a special LED illumination, and a mercury lamp. We examined effects of heading time and yield in rice when Oryza sativa L. cv. Hinohikari was irradiated by each kind of illumination at night. In the results, for irradiation by a common LED illumination and a mercury lamp, heading time was delayed and yield was reduced with increased illuminance, indicating the occurrence of light pollution. However, for irradiation by a special LED illumination, delayed heading time was unlikely to occur and the reduction in yield was small, indicating less light pollution.