It is well known that high pressure sodium lamps(HPS) contain toxic metals: mercury, which is not environmentally friendly; While LED (light-emitting diode) is mainly composed of semiconductor crystals, it is not only environmentally friendly, but also has many advantages in its performance.
The luminescence Angle of the HPS lamp tube is 360, most of which can be illuminated to the specified area only after being reflected through the reflector. The spectral energy distribution is roughly red, orange, yellow, green, blue, purple (only a small part). According to different ligh distribution design of LED, the effective luminescence Angle can be roughly divided into three categories: ≤180, 180 ~300 and ≥300. LED grow light source has wavelength adjustable, can emit narrow light wave monochromatic light, such as infrared red, orange, yellow, green, blue, etc., can be combined according to different needs.
HPS lamp has a wide range of use under conventional current, with high luminous efficiency and strong penetrating ability. The highest lifespan is 24000h, and the lowest can be maintained at 12000h sodium lamp for lighting. When it's working, it will be accompanied by a lot of heat generation. LED light as the fourth generation of new semiconductor light source, driven by DC, and its lifespan can reach more than 50000h, and its attenuation is small. As a cold light source, It can be irradiated close to the plants.
The price of HPS lamp is moderate, can be accepted by the broad masses of farmers, short-term response ability is better than that of the LED, its matching lighting technology has been relatively mature, and it is in widespread use. But HPS lamps need to install the ballast and related appliances,which increased its using cost.
Compared with HPS lamps,LED growth lamps have the advantages of more scientific spectrum, high safety and high reliability.The application of LED growth lamps in plant physiology experiments is very flexible, although the initial cost is high, but the long-term impact benefits on plants are much higher than the HPS lamps.
