Artificial lighting Supplement improving Greenhouse Productivity
Plant growth is inseparable from light. Light is the sole source of photosynthesis in plants. Light intensity, light quality (spectrum), and periodic changes in light have a profound effect on crop growth and development. Among them, light intensity affects plant photosynthesis maximum.The intensity of light can change crop morphology, such as flowering, internode length, stem thickness, and leaf size and thickness. Most vegetables are hi-light plants, and their light compensation points and light saturation points are relatively high. Understanding the light requirements of different plants is extremely necessary for designing artificial light sources and improving the production and performance of the system.
Light quality (spectrum) distribution also has important effects on plant photosynthesis and morphogenesis (Figure 1). Light is part of radiation, and radiation is an electromagnetic wave. Electromagnetic waves have wave properties and quantum (particle) properties. The quantum of light is called photon. Radiation in the wavelength range of 300 to 800 nm is called physiologically active radiation of plants; Radiation in the wavelength range of 400 to 700 nm is called photosynthetically active radiation (PAR) of plants. The two most important pigments in plant photosynthesis are Chlorophyll and Carotenes.
Figure 2 shows the spectral absorption spectrum of each photosynthetic pigment, in which the chlorophyll absorption spectrum is concentrated in the red and blue bands. The lighting supplement artificially supply lighting according to the spectral requirements of the crop to promote plant photosynthesis.
Generally speaking, the supplement light system includes light equipment, circuits and their control systems. The supplementary light source mainly includes several common types such as incandescent, fluorescent, metal halide, high pressure sodium and LED（Figure 3）.
Compared with ordinary fluorescent lamps, LED light have the advantages of energy saving, environmental protection, long life, monochromatic light, and cold light sources. With the further improvement of the electro-optical efficiency of LEDs and the cost reduction caused by scale effects, LEDs will become the mainstream equipment for supplement light in agricultural facilities.
A new type of mobile light supplement device designed and developed by Kingpeng can automatically adjust the height of the light supplement in real time according to crop growth. The adjustable device is now installed on a 3-layer light source lifting three-dimensional cultivation rack. The top layer of with best light conditions, so high pressure sodium lamps are configured; The middle and bottom layer are equipped with an adjustable system installed with LED lamps. Detection signal, automatically adjust the height of the light to provide a suitable light environment for crops.
Beijing Kingpeng International Agriculture Corporation
7th floor, Advanced Material Building, Feng Hui Zhong Lu, Haidian District,
Beijing, China, 100094