LED (Light Emitting Diode) light source is a new energy-saving light source developed in recent years. Compared with artificial light sources such as incandescent lamps, fluorescent lamps and high-pressure sodium lamps, LEDs have significant advantages:

　　·DC low voltage power supply. The forward voltage of low-power color LEDs is usually 1.5V-2.8V, and the forward voltage of high-power LEDs is usually 3V-4V, which is much less than the safe voltage.

　　·Energy saving. Sodium lamps and metal halide lamps are gas-discharge light-emitting lamps, which emit light by discharging metal element vapor by heating. LED is a solid luminous light source that can emit light without heating. It is a cold light source, so it reduces the amount of electricity consumed on heating.

　　·Monochrome light source, high luminous efficiency. LED can emit monochromatic light, and its half-wave width is mostly ±20nm, which can accurately provide plants with the required spectrum, without wasting electric energy to emit yellow light, green light and other unwanted spectra.

　　·Small size and flexible application. Light, thin, short and small lamps can be designed with large application space.

　　·Environmental protection. LED is a solid luminous light source and does not contain harmful substances such as mercury. It will not cause pollution during installation and use, and its waste can also be recycled. The LED light source is an environmentally friendly green light source.

  ·long life. LED is a solid light source, there are no loose parts inside, no glass, filament and other vulnerable and burnable parts. It has high mechanical strength, vibration resistance, impact resistance, and a life span of more than 50,000 hours.

　　 The obvious advantages of LED light sources have attracted the attention of scholars from the Netherlands, Japan, the United States and other countries. Especially in recent years, the successful research and development of high-power LEDs has laid the foundation for LED lighting applications in greenhouses.