Growing maize year-round in greenhouses requires supplemental lighting. Because maize requires high light for adequate growth and yield, high intensity discharge (HID) lamps (high pressure sodium vapor and/or metal halide lamps) are commonly used. Thedrawback of these lamps is the high level of heat generated mainly by infrared light. This makes it difficult to maintain constant temperature profiles, especially in summer, and is a cause of heat stress during pollen development. The vast amount of heat produced by these lamps might not only be problematic for the plants; it also is a waste of energy and causes unnecessary C02 emissions and energy costs. An alternative to HID lamps is light emitting diode- (LED-) based lighting systems. It has been shown that current LED lighting systems used for greenhouse illumination can cut energy costs by around 40%.
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