The plant factory subverts the traditional way of agricultural cultivation.

"create" a ray of sunshine for the plant factory

There is no soil, no sun, but the vegetables here are particularly green, and the yield is several times that of open-air planting.

Nutrient solution is soil, red and blue LED lights are sunlight, no pollution, diseases and insect pests. Here, through the high-precision control of the environment, the growth of vegetables is almost not restricted by natural conditions. Recently, the reporter saw a six-story cultivation shelf full of more than 10 kinds of hydroponic leafy vegetables, such as lettuce, Chinese cabbage, ice cabbage, and so on, in the Farmers' Union Plant Factory in Mafang Town, Pinggu District, Beijing.

Today, this plant factory, which has completely subverted the traditional way of farming, is changing or is about to change our dining table.

"Plant factory is an agricultural production mode with highly technology-intensive and efficient use of resources, and it is an important development direction for countries all over the world to ensure food safety." Yang Qichang, a researcher at the Institute of Agricultural Environment and Sustainable Development of the Chinese Academy of Agricultural Sciences, is one of the earliest experts to study plant factories in China.

Under the leadership of Yang Qichang, after 12 years of painstaking research, the project team has made a number of original achievements in plant light source adaptation theory and methods, light efficiency and energy efficiency improvement, nutrition quality control and multi-factor collaborative control technology. A series of products such as popular plant factories, island and reef plant factories, and low-carbon intelligent family plant factories have been formed, which have been popularized and applied in more than 200 parks and agricultural enterprises and institutions in more than 20 provinces, municipalities, autonomous regions and military systems, including Beijing, with remarkable economic and social benefits. In 2016, the project won the second prize of the Beijing Science and Technology Award.

An important symbol to measure the high-tech level of a country's agriculture

"Plant factory is an efficient agricultural production mode that realizes annual continuous production of crops through high-precision environmental control in facilities, and the output per unit area can reach more than 40 times that of open field production. therefore, it is regarded as an important development direction to ensure food security by countries all over the world, especially those countries with scarce cultivated land resources." Yang Qichang said.

China is a country with extremely scarce per capita resources, with per capita cultivated land only 40% of the world average, and per capita water resources only 25% of the world average. The task of ensuring food security is arduous. Vigorously promoting the development of high-tech industries in plant factories is in line with China's long-term strategic deployment.

Plant factories are characterized by a high degree of integration and application of technology, so they are considered to be an important symbol of a country's high-tech level of agriculture, just like aerospace engineering, maglev, large aircraft and other technologies. Developed countries will not easily let other competitors master, and must rely on independent research and development.

It is understood that Japan, the Netherlands and other countries began to study in the 1970s, and have made important progress in some key technologies such as plant plant system structure, nutrient solution cultivation and environmental control. however, due to the high energy consumption and high operating cost of the system, the large-scale application is still limited.

"how to break through the high energy consumption and high operating cost of plant factory system and highlight the technical bottleneck, greatly reduce the energy consumption of artificial light source and air-conditioning system, improve the quality of vegetables and realize the intelligent management and control of plant factories, the construction of a 'low-carbon, intelligent and efficient' plant factory production technology system is the key to the rapid popularization and promotion of plant factories." Yang Qichang said.

Grow vegetables without the sun

All things grow by the sun. Sunlight is not only the energy source of basic physiological activities such as photosynthesis, but also the power source of flower bud differentiation, flowering and fruiting. But in plant factories, the light needed by vegetables is illuminated by LED lights.

Yang Qichang told reporters that the artificial light sources currently used in plant factories are mainly fluorescent lamps and light-emitting diodes. LED can emit monochromatic light needed for plant growth (such as blue light with peak 450nm, red light with peak 660nm, etc.), and the combination of red and blue light LED can also form a spectrum which is basically consistent with plant photosynthesis and morphogenesis.

"compared with ordinary fluorescent lamps, LED mainly has the advantages of energy saving, environmental protection, long life, monochromatic light can be combined, cold light source and so on, so it is considered to be an ideal light source for artificial light plant factories." Yang Qichang said, "through different light quality combinations and light intensity and photoperiod regulation, artificial light sources can replace sunlight and meet the photosynthesis needs of vegetables and other crops in plant factories during the whole growth period."

Apart from being independent of sunlight, there is another magic thing about vegetables in plant factories, that is, they do not need soil. These well-growing vegetables are grown in a professionally customized cultivation module, where there is no soil under the module, but rely entirely on nutrient solution.

According to reports, this special "diet" of plants, which is often called soilless cultivation technology, is one of the technical cores of plant factories. These nutrient solutions are carefully prepared by professionals, which can provide all kinds of nutrients for plants in time and effectively, and can meet the nutritional requirements of different growth periods of plants to the maximum extent. it can also coordinate the conditions of water, fertilizer, air (oxygen) and temperature needed for plant growth, so that vegetables can grow fast and yield high.

In order to solve the outstanding problem of self-toxic substance accumulation and difficult removal by conventional methods in nutrient solution cultivation system of plant factory, the project team invented the technical method of combining UV (ultraviolet)-nano-TiO2 to deal with autotoxic substances in nutrient solution, and put forward and invented the vegetable quality control technology of short-term continuous light before harvest and nitrogen level regulation of nutrient solution.

"this technology can reduce the content of nitrate in leafy vegetables by more than 30%, and significantly increase the contents of Vc and soluble sugar." Yang Qichang said.

However, not all vegetables can be grown in plant factories. "as far as technical conditions are concerned, all vegetables can be grown in plant factories." Yang Qichang said, "however, because the plant factory adopts a three-dimensional and multi-layer cultivation model, in order to make full use of the cultivation space, low leafy vegetables (lettuce, small rape, celery, spinach, etc.), Chinese herbal medicine, edible fungi, strawberries and so on are generally chosen. For tomatoes, chili eggplants, cucumbers and other tall eggplant fruits and melons and fruits vegetables are not suitable for cultivation, even if they are cultivated, they should be planted with low varieties. "

Mastered the core technology of the plant factory

However, the realization of a plant factory is not easy. In the course of the research, the biggest challenge that Yang Qichang encountered was the research and development of special LED light source. Before 2005, the light quality of the common LED light source in the market was not consistent with the photosynthetic demand of plants, and the light intensity was weak.

Through various efforts and cooperation with other semiconductor light source research institutions, the project team developed a special LED light source board for plant factories in 2005, and built a small-scale laboratory for LED artificial light plant plants, which accelerated the progress of research and development of artificial light plant plants.

Yang Qichang told reporters that plants grow in the artificial environment of plant factories, the core element is the light environment, and the first difficulty to solve is the study of plant light formula, which is the core of the creation of plant LED light source. At the same time, due to the large energy consumption of plant factories, energy-saving environmental control technology can be described as the "life" of plant factories. "if the energy consumption is very large, the development is limited."

In addition, the realization of intelligent control is also one of the difficulties. "the detection and control of environmental and nutritional elements is very different from traditional agriculture." Yang Qichang said, "High-tech means are needed, including the integration and application of information technology, intelligent equipment technology, Internet technology and other technologies."

How to break through the key technical bottleneck of high energy consumption and high operating cost of plant factory system, greatly reduce the energy consumption of artificial light source and air-conditioning system, improve the quality of vegetables and realize the intelligent management and control of plant factory? the construction of a "low-carbon, intelligent and efficient" plant factory production technology system is the key to the rapid popularization and promotion of plant factories.

"to develop the high-tech industry of Chinese plant factories, we must rely on independent research and development to achieve breakthroughs in core key technologies such as the creation of plant light formulations and artificial light sources, energy-saving environmental control and intelligent control, otherwise they will be controlled by others." Yang Qichang said.

After long-term research and exploration, Yang Qichang led the research team to take the lead in the systematic exploration of plant light formula, found out the optimization parameters of plant light formula based on LED, invented the multi-light quality combination plant LED energy-saving light source based on AIGaInP red 660nm chip and InGaN blue 450nm chip as the core, and developed horizontal and vertical movable LED dynamic light environment control technology based on plant development characteristics, which significantly reduced the energy consumption of light source.

The project team also developed the environment-nutrition multi-factor collaborative technology to improve the light efficiency, energy efficiency and nutrition quality of plant factories, and integrated to create three series of intelligent LED plant plant products. The logic control strategy and algorithm of multi-factor cooperative control based on light formula, light-temperature coupling and nutrition quality improvement are explored, and the intelligent management and control technology of plant factory based on Internet of things is developed, which can realize on-line detection, remote access, program update and network intelligent control of plant factory temperature, humidity, light, CO2 concentration and nutrient solution EC, pH, DO and so on. Integrated to create three series of intelligent LED plant plant complete sets of technical products: large-scale mass production, mobile, home micro plant factory.

It already has the conditions for large-scale promotion.

It is understood that China is already the country with the fastest development of plant factory industrialization, and it has gone through the development road of developed countries in a few years. At present, the total number of artificial light plants in China has reached more than 100, making it a developing country second only to Japan in the number of plant factories. More and more people begin to taste vegetables from plant factories.

Among them, Yang Qi's team made an important contribution. Since 2003, after 12 years of innovative research and development, the research group has successively developed a series of products, such as popular plant factory, Xiamen plant factory, island reef plant factory, low-carbon intelligent family plant factory and so on. and took the lead in the demonstration and promotion in Beijing, and has been extended to more than 200 application units in more than 20 provinces, autonomous regions and troops across the country, saving 280 million degrees of energy consumption.

As the earliest demonstration base of R & D and industrialization of the project, the results of the project have been widely used. It has cultivated the two largest plant factory production enterprises in China-- Beijing Yida facilities Horticulture Technology Co., Ltd., and Beijing Jingpeng Global Technology Co., Ltd., these two companies have become the leading enterprises in the promotion of plant factories.

"at present, people's demand for high-quality vegetables is increasing, and the price of hydroponic vegetables in plant factories is also gradually accepted. more and more enterprises are participating in the construction, production and operation of plant factories, and the technology and equipment of plant factories are becoming more and more mature. already have the conditions for large-scale promotion." Yang Qichang said. (source: science and Technology Daily) operator: Zhou Hui MZ019