The hottest plant factory in Japan and its new tec

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Japanese plant factories and their new technologies

I. overview

1 Definition, classification and significance of plant factory

the term "plant factory" was first put forward in Japan. Its concept covers facility gardening in a broad sense, and refers to artificial light plant production system in a narrow sense. According to the current situation of plant factories in Japan, plant factories are the general name of nutrient solution cultivation systems with complete control and sunlight utilization. The Japanese plant factory Association defines a plant factory as a system that uses automatic environmental control, electronic technology, biotechnology, robots and new materials to carry out annual continuous production of plants, that is, a labor-saving production that uses computers to automatically control the temperature, humidity, light, carbon dioxide concentration, nutrient solution and other environmental conditions of plant growth, so that the plant growth in the facility is not restricted by the natural climate

the production objects of plant factories include vegetables, flowers and fruit trees, as well as some field crops, edible fungi, etc. According to the different levels of its research objects, plant factories can be divided into: plant factories in a narrow sense that mainly study plant bodies, tissue culture systems that mainly study plant tissues, and cell culture systems that mainly study plant cells. In addition, according to the different forms of sunlight utilization, plant factories in a narrow sense can be divided into three types: fully controlled type, sunlight utilization type and sunlight combined type

plant factories are of great significance to Japanese agriculture. The first is to improve the productivity of its agriculture, use a high degree of environmental control technology on limited land, and improve the land output rate and labor productivity; Secondly, in order to make agricultural production in cold, hot, desert and other barren areas possible, this paper mainly analyzes the common faults and causes of the universal tensile and pressure testing machine we widely used, and puts forward some troubleshooting methods; The working environment in the plant factory is superior, mechanized production is implemented to save labor, and the centralized labor is averaged every year; Carry out pesticide free production, and provide fresh and high-quality green food; Use nutrient solution cultivation to reduce continuous cropping obstacles and produce steadily in a planned way every year. However, plant factories carry out high input and high output production activities, with large equipment investment and high power consumption, so the production cost is high. For example, the cost of each lettuce produced by a sunlight utilization plant factory is about 50 yen, while the cost of a fully controlled plant factory is more than 100 yen

2. The history and current situation of the development of plant factories

Hitachi production took the lead in developing plant factories in Japan in 1974, and then the research of plant factories became popular. By the end of 1975, many enterprises and universities also joined the research ranks. At that time, the research still separated the automation of nutrient solution cultivation from plant factories. It was not until 1985 that the number of plant factories increased rapidly in a short time, reaching a climax of the development of plant factories in Japan

early plant factories focused on research, and there were also practical plant factories that could produce leafy vegetables, radish, celery and mushrooms, mainly lettuce. In recent years, there are more and more plant factories in the form of production and management and demonstration agricultural parks. As of 1997, there were 16 plant plants in actual operation, with an area of about 1.5h square meters and an annual output of about 550t, mainly engaged in the production of lettuce, tomatoes, strawberries, spinach, roses and some tissue culture seedlings, of which the sunlight utilization type was 1H square meters, the annual output was 287T, the fully controlled type was 0.5h square meters, and the annual output was 260t. By 2001, it had increased to more than 20, covering all parts of Japan

with the development of plant factories, some related research institutions, organizations and enterprises continue to be established, and related activities are increasing. For example, the plant factory Association of Japan holds a national academic conference every year, and the plant factory popularization and revitalization association actively carries out the promotion and application work, while maintaining close contact with the facility Gardening Association, the biological environment regulation association, the Meteorological Association, the lighting association, the electrical association, etc., to ensure the progressiveness and practicality of its research level

II. Main technologies

1 Nutrient solution cultivation techniques

there are many methods of nutrient solution cultivation in Japan, such as NFT, zhanye culture, spray culture, solid substrate culture (including rock wool culture, gravel culture, sand culture, etc.), of which rock wool culture and NFT are the main ones, and rock wool culture accounts for nearly 50% of the nutrient solution cultivation area. The typical nutrient solution cultivation device has the following forms: ① three water NFT device - the cultivation bed is made of foam, which verifies that the structure/process scheme and design requirements have a certain slope (1/80-1/100), the bottom nutrient solution flows slowly in a film shape, which can automatically supply fertilizer, and is also equipped with a sterilization device; ② Concorde type - using plastic cultivation bed, divided into several units, suitable for fruit and vegetable cultivation; ③ Type M - the cultivation tank is connected with the formed products made of "U" type foam, and the planting board is also made of foam, which is covered with polyethylene film, suitable for the cultivation of leafy vegetables, especially duck celery; ④ Xinhe equal exchange device - its main feature is that the cultivation tank is divided into two parts, and the nutrient solution is exchanged equally with each other to supply sufficient oxygen to the root system (②, ③, ④ all belong to zhanye cultivation device); ⑤ Chenghe type - this is a circulating rock wool cultivation device. A drainage pipe is installed in the center of the cultivation tank, and granular rock wool pads, rock wool blocks and shaped irrigation pipes are laid from bottom to top. Drip irrigation is adopted, and the excess nutrient solution flows back to the water collecting tank through the drainage pipe for recycling. Mobile cultivation devices are mostly used in plant factories, mainly including plane type, three-dimensional type and inclined type. Through reasonable close planting, the effective cultivation area is increased

the theory of nutrient solution in Japan is very mature. Among them, the garden trial standard formula developed by Xingjin horticultural laboratory is universal and applicable to a variety of vegetables, while Yamazaki formula is a proprietary formula for each crop. These two formulas are also widely used in China. In addition, the travel problem is an important step in the purchase of tensile testing machine. There are also Shenyuan formulas. The research and application of nutrient solution management, sterilization, recovery and treatment, disease prevention and control in Japan have also reached a high level. The development of nutrient solution cultivation technology has promoted the improvement of plant factory level. Compared with soil cultivation, nutrient solution cultivation can accelerate the growth process of crops, and increase the number of cultivation crops a year by 15%-20%. For example, lettuce and celery can be cultivated for 6 crops a year, onion for 4.8 crops, cucumber and tomato for 1.8 crops

2. Environmental control technology

in order to achieve the goal of annual continuous production in plant factories, environmental control is an important technology

(1) crop growth and its environment. As a semi closed system, the plant factory constantly exchanges materials, energy and information with the outside world. The growth of its internal crops is affected and restricted by the following environmental factors: light (light intensity, light quality and sunshine length), temperature, humidity, C02 gas concentration, wind speed and root environmental factors such as pH, EC, fertilizer composition, dissolved oxygen, liquid temperature, flow rate, etc. To optimize and control the environment of plant factories, the most fundamental thing is to clarify the relationship between physiological processes such as crop photosynthesis, product accumulation, diversion and distribution, development and respiration and all or part of environmental factors. However, due to the following three problems, the environmental control of plant factories is not simple: first, various environmental factors do not act independently on crop growth, but the result of the comprehensive action of various factors; The second is to control the cost; Third, the maximum output does not mean the highest quality

recently, Japan's research on the effects of electromagnetic fields, sound, far infrared and other physical stimuli on crop growth has been particularly noteworthy, but the mechanism of their effects is still unclear

(2) principles and methods of environmental control. Plant factories, especially fully controlled plant factories, need to consume a lot of power for lighting and air conditioning in order to control light, temperature and other conditions. The cost of environmental control is very high. At the same time, there is a law of diminishing returns in environmental control, that is, when the control cost increases to a certain extent, it continues to increase, and the control effect is getting smaller and smaller. Therefore, in the plant factory, we should comprehensively consider the compound effect of various environmental factors. First, it is reasonable to optimize the factors with low cost and good effect. This is a commonly used control method, which is called the optimization principle. With this method, the factors with low cost can be used to make up for the factors with high cost, and a better comprehensive control effect can be achieved

the methods of environmental control in Japanese plant factories mainly include the following two categories: ① process control feedback control, on-off control, PID control; ② Computer control - distributed control, time-sharing centralized control, hierarchical networking control, optimization, adaptation and intelligent control

III. latest development

in recent years, many latest technical reports in this field have been published in the Journal of the Japanese plant factory Association and related academic conferences, which are mainly concentrated in the following aspects: ① artificial fill light technology, including the development of short-range and efficient intermittent fill light of fluorescent lamps, the development of ultra wide-angle lamps of high-pressure sodium lamps, and the development of new light sources such as LED and laser diode LD; ② Development of nutrient solution sterilization (thermal sterilization, ultraviolet sterilization, ozone sterilization) system; ③ Using image processing and communication technology for long-distance cultivation management; ④ Research on locking system CELSS; ⑤ Functional pesticide free vegetables and quality evaluation; ⑥ Virtual technology of plant factory planning and design; ① Using biotechnology for tissue culture, breeding and transgenic research; ⑧ Informatization, networking and intellectualization of cultivation management (expert system, decision support system); ⑨ Development of seedling factories and underground plant factories; ⑩ Monitoring of crop physiological information; ⑩ The automation technology of plant factory and the application of Internet technology in plant factory

IV. outlook

at present, the development of Japanese plant factories has reached a high level, and the research and application in some fields have exceeded those in the Netherlands, Israel and other countries with relatively developed greenhouse industry, but they still face many technical issues to be solved urgently. In order to promote the industrialization process of plant factories, it is very important to develop hardware and software technology with reducing production costs as the core

in the 21st century, plant factories will play an increasingly important role in Japanese agriculture, opening up a new way to solve food problems, environmental problems, and even the development of the universe

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