1 application status
1.1 The need to intelligently control lighting in agricultural applications
1.1.1 Illumination is a plant growth element
At present, human beings face five major problems of food, energy, resources, environment and population. The solution of these problems is closely related to plant production, and illumination is the primary factor affecting plant growth and development. Therefore, it is a meaningful and innovative work to study the characteristics, laws and light control benchmarks of plant growth and development on light, and to develop an intelligent control high-efficiency LED light-filling system suitable for plants to provide an efficient light environment for plant growth. .
The scarcity of land resources and the growth of population determine the scarcity of plant cultivation land. At the same time, as people's quality of life continues to improve, the demand for green, safe and healthy edible plants is becoming more and more urgent. The demand for cultivation system systems for agricultural plantation, production refinement and intelligent facilities, including the need for intelligent control of lighting technology, is increasing.
In addition, the use of intelligent control of LED lighting to promote plant growth can meet the needs of vegetables in remote outposts, polar, underground air-raid shelters and small island guards, as well as the annual supply of fresh vegetables, saving a lot of transportation costs. This opens up a new avenue in the field of modern agriculture.
1.1.2 Application of intelligent control lighting is a mileage indicator of modern agricultural models
In recent years, with the increasing air pollution, the atmospheric transparency coefficient has been declining, resulting in the reduction of solar radiation reaching the surface, and the solar energy that plants can receive is less and less, which is difficult to meet the needs of normal growth and development of plants. In addition, the global warming has caused abnormal weather, the frequency of continuous rainy and hazy weather in plants has increased, and the stable harvest of farmland crops has become unreliable.
Therefore, in order to improve the photosynthesis efficiency of crops, promote crop growth, reduce the use of pesticides and hormones in crop planting, and develop high-efficiency and pollution-free green agriculture, light environment control technology should be used in vegetable facility cultivation. It is a new physical method that is energy-saving, environmentally friendly, cost-effective and easy to use, with outstanding technical advantages. Therefore, the use of intelligent control of light plant plant high-yield cultivation is a trend in agricultural development.
The agricultural production mode has undergone major changes from open field cultivation to facility cultivation mode and soilless cultivation, and is also developing towards a factory cultivation mode. The plant factory cultivation mode is based on the latest development of soilless culture. The plant factory cultivation mode based on intelligent control lighting can completely get rid of the constraints of natural conditions and is the advanced stage of modern agricultural development. Stable production can be achieved according to the planned cycle, which is the mileage mark of the modern agricultural model.
1.1.3 Promoting the transition from modern agriculture to green environmental protection
In nature, the illuminance of the sun varies with geographic latitude, season, and weather conditions. In addition to the above factors, the illuminance in the greenhouse is closely related to the structure of the greenhouse, management measures and the light transmission properties of the materials. Due to factors such as greenhouse cover materials, dust and structural shading, the quality of light in the greenhouse is much worse than that of open land, generally only 30% to 70% of open ground, especially in winter and early spring, where the solar altitude is low. The sunshine time is short, and the illumination in the greenhouse often cannot meet the needs of crop growth. Insufficient illumination severely inhibits the development of fruits and vegetables in the greenhouse, the slow growth of plants and the more serious diseases, resulting in a significant reduction in production and quality. Crops rely mainly on hormones and pesticides to protect against various problems caused by insufficient light, resulting in excessive use of chemicals and residues that endanger human health. Intelligent control is used to adjust the fill light of plants, increase the number of illumination hours, improve the indoor spectral distribution and promote plant growth, and promote the transition from modern agriculture to green environment.
1.2 Agricultural intelligent control lighting is highly valued by all countries
Plant factories have changed the traditional concept of agricultural production and improved their ability to withstand natural disasters through a technological revolution that intelligently controls LED lighting. The application and research of intelligent control lamps in the field of plant cultivation has been increasingly valued by countries all over the world. In the United States, Japan, Germany, Northern Europe and Canada, various plant factories have been developed for future agricultural production. Open up new paths.
1.2.1 Mitsubishi, Japan - Container Plant Factory
The application of intelligent control lighting in agriculture mainly includes plant production, aquaculture, microalgae cultivation, and cultivation of edible fungi. In April 2010, Mitsubishi Chemical Corporation of Japan transformed large-scale containers into “plant factoriesâ€, which use LED as a light source to carry out photosynthesis of crops. In order to meet the needs of the new plant factory, Showa Denko has developed an intelligent control LED lighting product for the "plant factory" that can emit specific wavelength light that promotes the growth of crops. It has been adopted by more than 10 plant factories in Japan.
1.2.2 Ministry of Economic Affairs of Korea - Cultivation Base
In June 2010, the Korean Ministry of Knowledge Economy also announced that it will invest 3 billion won (about 16.5 million yuan) for research and development of core components and core technologies for IT-LED cultivation. At the end of 2010, chip development has been completed and a scale of 495m2 has been built. Intelligent cultivation of LED lighting cultivation base.
1.2.3 China Institute and Enterprise Start Simultaneously
As early as 2009, the research and development team of the Chinese Academy of Agricultural Sciences has successfully developed the first intelligent plant factory in China, using intelligent control of LED and fluorescent lamps for artificial light source for vegetable planting and seedling breeding, and put into operation in Changchun. In 2010, the 863 Program of the Agricultural College of Nanjing Agricultural University, “Application Research of Semiconductor Lighting Sources in Plant Tissue Cultureâ€. In 2014, Beijing Lighting Exhibition, the first in China to open up the “Agricultural Lighting Theme Zone†to cater to the development of industry and market, invited LED industry and plant factory planners and relevant agricultural departments to participate. The “Intelligent Plant Factory Production Technology Research†project of the 12th Five-Year Plan was officially launched in Beijing in the first half of 2013. The application of energy-saving light source in plant factories and the intelligent control technology of light environment have become hot topics. Intelligent control technology has been successfully applied to the cultivation of plants, and has made important progress in the field of plant supplementation, tissue culture, and plant factories.
At a time when countries are competing for development, China, which is a self-proclaimed agricultural country, has also followed this development trend and actively joined the field of intelligently controlling agricultural lighting. Together with international LED manufacturers, it has established a strategic alliance for research and development of LED plant factories. At present, the horticultural area of ​​facilities in China has reached 337 hm2, of which solar greenhouses account for about 25%, making it the most important and important planting industry. The number of lamps for agricultural lighting in China is more than 1-5 billion. With the development of modern agriculture and the increase in the number of lamps used, it is expected to increase to more than 500-100 million in the next few years. Therefore, the demand for agricultural lighting is very urgent, and the prospects for agricultural lighting and its intelligent control equipment industry are attractive. The establishment of Chinese plant factories is still dominated by national policies, and the positive footsteps of local governments also allow operators to smell subsidy business opportunities. There are many domestic manufacturers entering the agricultural lighting application field, mainly distributed in South China.
1.3 Application of intelligent control in agricultural lighting
Agriculture is the foundation of the national economy. A large part of agricultural and sideline products such as meat, eggs, vegetables, flowers, fruits and edible fungi in daily life are produced under the conditions of the facilities. Intelligent control of light and lighting is the agricultural field. The most important application method, according to the different needs of animal and plant development, the combination of monochromatic light of different wavelengths to form an agricultural lighting system, and through the adjustment of light intensity, light quality and photoperiod, to achieve energy saving and efficient production, has become a modern The important application direction of agriculture. At present, the application of intelligent control in agriculture has been extended to many fields such as plant cultivation, livestock and poultry breeding, edible fungi production, microalgae reproduction, pest trapping, and attracting fish.
1.3.1 Plant cultivation
During the whole growth process of plants, it involves photosynthesis, photoperiod regulation, photoecological formation, etc. The absorption of light by plants is not full-band, but selective according to the growth cycle. Light regulates the growth and development of plants to better adapt to the external environment. This change in the differentiation, structure and function of cells that rely on light control will eventually inherit the establishment of tissues and organs, and become a process of light-formed light control development. Light plays a role in the formation of light, which is different from the role of energy in photosynthesis.
Studies have shown that plant photosynthesis absorbs about 60% to 65% of its physiological radiation energy in the visible spectrum (380-760nm), mainly red light with a wavelength of 610-720nm (wavelength of 660nm). Orange light (about 55% of physiological radiation) and blue light and violet light (about 8% of physiological radiation) with a wavelength of 400 to 510 nm (wavelength of 450 nm) are absorption peak regions. Therefore, the development of plant artificial light sources with these two bands (especially wave peaks) as the main body will greatly improve the efficiency of light energy utilization.
The intelligent control lighting system emits monochromatic light required for plant growth (such as blue light with a peak of 450 nm and red light with a peak of 660 nm), with a spectral width of only ±20 nm, and the combination of red and blue LEDs. It forms a spectrum that is basically consistent with plant photosynthesis and morphogenesis. The utilization rate of light energy is 80%-90%, and its energy-saving effect is extremely remarkable. The unique properties controlled by intelligent lighting provide a wide application space in plant production systems such as greenhouses, plant tissue culture, genetic breeding and plant factories.
1.3.2 Livestock and poultry farming
Through the research on the influence of red, blue and white LED light sources on poultry production performance, an intelligent chicken LED lighting system was introduced and put into use in chicken farms. ONCE has introduced a gradual poultry farming intelligent control lighting product that uses a timing system to control the photoperiod. Modern aquaculture industry generally uses artificial intelligence lighting to promote production, especially in large-scale facility farms. Because artificial color control lighting color temperature, light intensity, duration and intermittent control will affect the behavioral habits, physiological characteristics, growth and development of livestock and poultry, and ultimately promote the production performance of livestock and poultry. Therefore, the lighting in the production of aquaculture should not only have low energy consumption and long life, but also have controllability of light environmental parameters.
1.3.3 Microalgae reproduction
With the global resource, energy and environmental crisis intensifying, the development and utilization of photoautotrophic microalgae directly converts solar energy and CO2 into medicines, bio-based chemicals (such as natural pigments, isoprene, etc.) that people need for life. Bio-energy (such as ethanol, butanol, biodiesel, etc.) has become the focus of attention in countries around the world. Light is one of the most important factors affecting the growth and biochemical composition of microalgae cells. It has an important influence on the growth, reproduction, algae color, cell morphology and metabolite content of microalgae. Intelligent control light source gradually propagates in microalgae. Widely used in applications.
1.3.4 Aquatic trapping
There have been ways to use fire or other forms of light fishing around the world, and these methods of fishing have become an important feature of modern fisheries in many countries. Some researchers have also tested the effect of different color light sources. The results show that blue light has deeper water penetration, and the use of blue-based artificial light source can achieve better trapping effect.