[Special] Modern agricultural lighting status and development prospects

0 Preface

Agriculture relies on the natural growth and development functions and breeding functions of animals, plants and microorganisms to achieve the biological production method for the purpose of large-scale production of agricultural products. As the saying goes, all things grow by the sun. Sunlight is the source of energy for the survival of the earth's biology. It is an indispensable environmental condition for openland agriculture. The quality of light directly determines whether agricultural production can obtain high quality and high yield. In recent decades, China's agriculture has gradually experienced a transition from traditional agriculture to facility agriculture, and is shifting towards the direction of modern agriculture. In this transformation process, the level of management and control of agricultural production environmental factors has gradually increased, and the degree of factory production of agricultural products has increased substantially. . Traditional agriculture (taking farming as an example) relies almost entirely on natural resources for production. The degree of human intervention is small. It can only regulate the rhizosphere environment through agronomic means such as fertilization, irrigation and farming. The above-ground environment cannot be regulated and cannot be produced annually. . Among many environmental factors, illumination is the most important environmental factor, and its quality depends entirely on solar radiation and weather conditions, and cannot be artificially regulated. At the stage of facility agriculture, people can adjust the growth and yield of plants by supplementing light, and initially get rid of the natural conditions of agriculture and have the ability to produce on an annual basis. Modern agriculture, as a modern industrial, modern science and technology and scientific management method, is equipped with agriculture [1], which is an inevitable trend of future development. It can realize the controllable management of all factors in the whole process of production and achieve the goal of on-demand production.

1 The necessity of modern agricultural lighting

In the 1980s, with the development of agricultural engineering technology, the emergence of solar greenhouses, China's facility agriculture was initially formed. The greenhouse has the ability of heat storage and heat preservation, the environment inside the facility is controllable, and the initial production is initially realized, which provides conditions for the supplemental light of the artificial light source to achieve the goal of synergistically improving the crop yield of the facility. However, due to the greenhouse structure and shed film, the light in the facility is reduced by 20% to 50% compared with the open field, and the frequency and intensity of weak light illuminating stress increase, which seriously affects the quality of facility horticulture.

High production, increased demand and urgency for the regulation of the facility's light environment. On the other hand, the facility artificial light facility horticultural industry has developed rapidly, such as plant tissue culture, vegetable cultivation, seedling cultivation, edible fungus cultivation, etc. can be carried out under completely artificial light, and more needs the light environment demand characteristics based on agricultural organisms. Appropriate light ambient conditions are provided by artificial light sources. Similarly, the need for artificial light environment regulation in the livestock and poultry breeding industry is also very urgent. Artificial light not only provides visual service functions for animals, but also regulates non-visual functions such as animal behavior, growth and reproduction, and production is of great significance. For modern agriculture, the demand for artificial light illumination is necessary and urgent, which depends first and foremost on the inherent nature of the facility's agricultural production. Facility agriculture is a way of promoting production. It is to promote or delay the growth and reproduction of agricultural organisms through environmental control, and to obtain the required animal and plant and edible fungi products according to human time and space requirements. In order to achieve higher yield and quality, all environmental factors related to agricultural biological production, including light, need to be regulated, and lighting is the first to bear the brunt. Second, the regulation of light environment is the requirement of modern agricultural development. The development goal of modern agriculture is “high yield, high efficiency, high quality, ecology and safety”. To this end, it is necessary to adjust the lighting conditions as needed, otherwise the target cannot be achieved. Secondly, the regulation of light environment is the actual objective demand of modern agricultural development, which is mainly manifested in two aspects. First, artificial replenishment of the greenhouse is necessary and urgent. Even the rain, snow, haze, air pollution and other facilities caused by weak light and light stress often cause serious production hazards, resulting in crop yield reduction or even failure; and high-latitude, short-day sunshine areas urgently need photoperiod regulation. In order to overcome the above-mentioned problems of light environment, supplemental light is an effective way. Second, there is an urgent need for artificial light facility cultivation and facility farming. Accurate and intelligent light environment regulation is the decisive factor for high-quality, high-yield, energy consumption and production efficiency in artificial light plant tissue culture, plant factories, edible fungi factories, livestock and poultry breeding, etc. The necessity is very prominent.

2 Application fields of modern agricultural lighting

The application fields of modern agricultural lighting are diverse, and the biological forms of various fields are different. The requirements of light environment are quite different, mainly including the following fields: First, the field of facilities and horticulture. China's facility horticultural cultivation area has reached 3.8 million hectares, and artificial light cultivation (plant tissue culture, plant factory, edible fungus factory) covers an area of ​​over 2,000 hectares, and the industrial scale has increased year by year. The mode of light environment regulation in the field of facility horticulture includes the following aspects: (1) Greenhouse fill light. China's solar greenhouses and multi-span greenhouses cover an area of ​​about 1 million hectares. In order to increase the photosynthetic yield of plants and prolong the photoperiod of plant illumination, artificial light supplementation must be carried out. (2) Edible fungus factory. Edible fungi are important vegetables and health products. In 2012, the total production of edible fungi in China was nearly 30 million tons, and the output value exceeded 150 billion yuan, accounting for more than 70% of the world's total output. At present, the production of edible fungi is highly industrialized. Most edible fungi do not require high light intensity, but the light quality is demanding, the yield quality effect is large, and the light environment regulation is very important. (3) Plant factory. As the most advanced development stage of facility gardening, plant factories can be used for large-scale production of vegetables, seedlings (vegetable seedlings, rice, tobacco, etc.) and Chinese herbal medicines [2]. It is estimated that the artificial light plant factory leaf production efficiency is 108 times that of open field [3], intelligent artificial light source and its light environment regulation play a decisive role in its production efficiency. (4) Plant tissue culture. Plant tissue culture is an important means for rapid propagation and detoxification of seedlings. It is completely produced by artificial light, and the demand for artificial light sources is extremely high. Followed by the livestock and aquaculture sector. Intensive chicken farms, pig farms, etc. must be artificially illuminated. Studies have shown that the color, intensity, duration and intermittent control of artificial lighting can stress the behavioral habits, physiological characteristics, growth and development of farmed animals, and ultimately affect the growth and reproduction performance of animals. Artificial lighting has broad application prospects in livestock and poultry breeding. In addition, it also includes lure and trap light applications. LED lure lamps and LED traps have important applications and are ecologically efficient.

3 The inevitable trend of modern agricultural lighting

Historically, the development of facility agricultural lighting technology and industry is closely related to the development of electric light source technology. The emergence and development of electric light sources such as incandescent lamps, fluorescent lamps, high-intensity discharge lamps and LED lamps have contributed to the development and transformation of agricultural lighting, and at the same time expanded the connotation and extension of agricultural lighting. Some scholars pointed out that the fourth generation of light source--LED application in agricultural lighting is the biggest advancement in the development of agricultural lighting, with a milestone significance [4]. This argument is mainly based on the following reasons: (1) LED greatly expands the connotation of agricultural lighting, and can modulate the spectrum according to the growth and development and reproductive needs of agricultural organisms. The light quality, light intensity and photoperiod can be comprehensively controlled, and light is used as needed. High bio-efficiency; (2) LED controllability, accurate and intelligent control of light environment, suitable for factory production; (3) LED light source devices, such as: light panels, strips, tubes and bulbs, etc. It is suitable for applications in various fields of facility agriculture; (4) LED is a cold light source, close to agricultural biological irradiation, which can improve space utilization; (5) LED has the characteristics of energy saving, environmental protection, long life, small size and light weight. Therefore, LED light source is considered to be the ideal light source for modern agricultural lighting, and semiconductor lighting will gradually replace traditional light sources and is widely used in various fields of agricultural production [5].

4 Problems in modern agricultural lighting

At present, modern agricultural lighting has certain problems in scientific research, technical equipment research and development, and promotion and application. First, in terms of scientific cognition. China is seriously lagging behind in the study of the laws of agricultural photobiology. One of the reasons: The diversity and complexity of agricultural biological nutrition and growth and development, the response mechanism of agricultural organisms to light environment are different, the research methods are different, and it is necessary to systematically study one by one to reveal its photobiological laws. Plants use light energy, CO2 and water to form carbohydrates through chlorophyll photosynthesis and convert light energy into chemical energy. Animals digest feed or food through digestive enzymes to convert chemical energy into bioenergy; For example, the bacteria need to be decomposed by extracellular enzymes to obtain the desired nutrients to produce hyphae and fruiting bodies. The second reason: The agricultural production field is complex, and the living conditions of agricultural organisms are different, and the time and space requirements for the light environment are different. The areas involved in agricultural lighting are: (1) Facility gardening (including greenhouse light filling, vegetable production, group breeding, seedling cultivation, edible fungus production, etc.); (2) Facility farming and aquatic products (including broilers, laying hens, Fish, pigs, etc.); (3) Fish light and trap light (including fish, insects). The third reason: the quantitative properties of the light environment (ie, light intensity and photoperiod), mass properties (ie, light quality and spectrum), and electric light source luminescence characteristics (ie, duty cycle, frequency) are many, and the biological effects need to be studied one by one. Secondly, in terms of scientific research and technology research and development, the research and development of traditional light sources and LED light sources is insufficient, and there is no suitable product. The application of semiconductor lighting agriculture is in its infancy, and China, Japan, South Korea, the United States, and the Netherlands are stepping up research and development of agricultural LED lamps. The United States, Japan, and South Korea have successively proposed research projects for semiconductor agricultural lighting. China has also invested in the development of LED light sources in 863 major projects (non-visual lighting projects), 863 projects (intelligent plant production technologies), and national science and technology support programs. Question. Finally, at the level of achievement transformation, there is a lack of a national platform for communication between enterprises and research units. There is a lack of a national exchange platform for the research and development of LED agricultural lighting products and the transformation of results. The LED manufacturing enterprises involved in agriculture are not able to transform their innovation and achievements. At present, agricultural lighting technology is weak, light source equipment is not cost-effective, lack of government support (research projects, product subsidies, results conversion funds, etc.), poor development and productization channels of electric light sources, low promotion and application rate of lighting products, and difficult application of LED light sources Other real problems still exist.

5 Modern agricultural lighting development prospects

The application prospect of modern agricultural lighting is very broad. It is estimated that its industrial scale is over 100 billion yuan, and it will have a great development in the next 5 to 10 years. Nursery plants, plant factories, edible fungi factories and livestock and poultry farming will be the priority areas for the development and application of LED lamps, and the benefits are considerable. Fundamentally speaking, the development of modern agricultural lighting must have a national communication platform to strengthen the docking between research institutes, universities and lighting enterprises, promote the transfer of agricultural lighting technology and the upgrading and application of product equipment, and gradually Establish an agricultural lighting product evaluation and measurement standard system to improve the scientific and technological contribution rate of agricultural lighting to modern agricultural development. 110711.png110711.png110711.png110711.png

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