Effect of temperature rise in LED on photosynthetic photon flux and an attempt of heat removal by ventilation.

Recently, LED is being used as a light source for the cultivation of plants. However, the temperature rise of LED due to heat generation reduces the photosynthetic photon flux (PPF) of LED. Therefore, it is important to develop a method for heat removal. We report the effects of temperature rise in LED and heat removal by passing air either to the LED lamps or to the space between two circuit boards on PPF.We found that the PPF of LED is reduced by more than 30% in half an hour after lighting under the condition without heat removal. Thus, the method of heat removal attempted in this study seems to be effective for small scale light sources.