Research progress and application status of LED in agricultural lighting

First, the demand for modern agricultural lighting source

Agriculture is the foundation of the national economy, a large part of daily life in the meat and milk, vegetables, flowers, fruits, edible fungus and other agricultural and sideline products are produced under the condition of facilities, of which agricultural lighting plays a very important role. Overall, in many areas of modern agriculture, such as plant production facilities, intensive aquaculture, fishing, pest control, edible fungus production and breeding of microalgae, has a very close relationship with artificial lighting.

Plant production requirement of artificial lighting, as the saying goes "all living things depend on the sun light is the foundation of biological growth, survival and reproduction of the earth, photosynthesis of crops without light illumination, the illumination condition directly affects the yield and quality of crops. In nature, the sun light with latitude, season and weather conditions vary, the high latitudes in winter the days are shorter in winter and spring and other areas, even the cloudy rain and snow, fog and other specific climatic conditions, illumination intensity and illumination time shortage have occurred, therefore, in the production system of modern plants (such as greenhouse etc.) artificial lighting has become an important means of efficient production. In addition, in the closed artificial light production system, such as plant plants, tissue culture workshop, nursery plants, etc., the use of artificial light for photosynthesis, it can not do without the need for artificial lighting light source.

In aquaculture production demand for artificial lighting, intensive chicken farms and pig farms are in the closed or semi closed environment for breeding, artificial light can not only play the role of lighting, but will also have an important impact on the production performance of livestock and poultry. A number of studies have shown that in livestock and poultry breeding, light color and wavelength, time and intensity, light and dark period of cooperation will have significant impacts on livestock and poultry production performance, physiological characteristics, behavior characteristics, physical health etc.. The suitable artificial lighting can overcome the seasonal limitation of reproductive physiological function of livestock and poultry, so as to maximize its genetic potential and increase the economic benefits of livestock and poultry breeding.

In the light of the demand for artificial lighting in the light of fishing and lighting, since the beginning of the eighth Century ad, the use of light to fish and fishing. Over the years, there has been the use of fire or other forms of light fishing around the world, and now these fishing methods have become an important feature of modern fisheries in many countries. Some scholars have also tested the effect of different color light sources, the results show that the blue light has a deeper penetration of the water, the use of blue as the main body of the artificial light source can achieve better fishing results.

In the aspect of artificial lighting needs of microalgae, in recent years, along with the global resources, energy and environmental crisis, the development and utilization of photoautotroph microalgae, directly to the pharmaceutical, bio based chemicals and solar CO2 transform into the production and living needs (such as natural pigment, such as isoprene) and bio energy (such as ethanol, butanol biodiesel, etc.), has become the focus of the world. Light is one of the most important factors affecting the changes of cell growth and biochemical composition of microalgae and microalgae growth and reproduction of algae, body color, cell morphology and metabolite content have important influence, as an effective means of artificial light gradually has been widely used in breeding of microalgae.

In addition, in the process of modern agricultural production, a large number of areas, such as pest control, edible fungi production, but also a wide range of artificial light sources.

For a long time, the use of lighting in the field of artificial light in agriculture are high pressure sodium lamp, fluorescent lamp, metal halogen lamp, incandescent lamp, highlight the shortcomings of these sources are high energy consumption, high operation cost, energy costs accounted for about 40% to 60% of the cost of running the system. Therefore, the development of energy-saving light source, high efficiency and low energy consumption has been an important topic in artificial lighting applications in agriculture. In recent years, with the rapid development of LED technology, the low power consumption, high light source can be used in the field of agriculture. Compared with the traditional artificial light, LED is not only a significant energy saving effect, but also can be light and light quality (red / blue or red / far red ratio Ratio) the adjusted to meet the various physiological needs of plant production, to achieve efficient production. Therefore, LED is considered to be the most promising artificial light source in the field of agriculture in twenty-first Century.

Two, LED agricultural lighting research progress

Research progress of 1.LED plant lighting

Long term studies show that plant photosynthesis in the visible spectrum (380 ~ 760nm) light absorption range about the physiological radiation light from 60% to 65%, in the range of 610 ~ 720nm (peak 660nm) red and orange light (about physiological radiation around 55%) and the wavelength of 400 ~ 510nm (peak 450nm), blue violet (accounting for about 8% of the physiological radiation absorption peak area). Therefore, it is necessary to develop the artificial light source with the two bands (especially the wave crest) as the main body. In recent years, with the development of LED technology, it is possible to achieve this goal. LED can emit monochromatic light needed for plant growth (such as the peak of 450nm blue, 660nm red crest), wide spectral domain only + 20nm, and the red and blue LED combination, can form consistent with photosynthesis and form of plant built