Japanese plant factory and its new technology

I. Overview 1. Definition, classification, and significance of plant factories The term “Plant Factory” was first proposed by Japan. Its concept covers facility horticulture in a broad sense, while in the narrow sense, it specifically refers to the production of artificial light plants. system. According to the current status of the Japanese plant factory, the plant factory is a general name for a fully-controlled and solar-utilized hydroponics system. The Japanese Plant Factory Association defines a plant as a system for the annual continuous production of plants using environmental automation, electronic technology, biotechnology, robots, and new materials, that is, the use of computers for the temperature, humidity, light, and carbon dioxide of plant growth. Concentration, nutrient solution and other environmental conditions are automatically controlled so that plant growth within the facility is not affected by the natural climate.
Plant plants produce objects such as vegetables, flowers and fruit trees, as well as a number of field crops, edible fungi, etc. According to the different levels of their research objects, plant factories can be divided into: a plant factory in the narrow sense focusing on plant research, a tissue culture system focusing on plant tissues, and a cell culture system based on plant cells. In addition, according to the different forms of solar light utilization, the narrowly-defined plant factories can be divided into three types: fully-controlled, solar-utilized, and sunlight combined.
Plant factories are important for Japanese agriculture. The first is to increase the productivity of its agriculture, use high-level environmental control technologies on limited land, increase land productivity and labor productivity, and secondly, make agricultural production such as cold, heat and desert a barren place; plant factories The internal working environment is superior, the implementation of mechanized production saves labor, and the annual anniversary of concentrated labor is equalized. With pesticide-free production, it can provide fresh and high-quality green foods; using nutrient solution culture to reduce continuous cropping obstacles, the annual plan is produced steadily. However, plant factories are engaged in high-input and high-output production activities. Equipment investment is large and power consumption is high. Therefore, production costs are high. For example, the cost of producing a lettuce plant in a solar-powered plant factory is about 50 yen, and that of a fully-controlled plant factory is more than 100 yen.
2. History and Current Status of Plant Plant Development In 1974 Hitachi Laboratories pioneered the development of a plant factory in Japan. Since then, plant plant research has become popular. By the end of 1975, many companies and universities had joined the research field. At that time, the research did not separate the automation of the hydroponic culture from the plant factories. Until the organic combination of the two in 1985, the number of plant factories rapidly increased in the short term, and reached a climax in the development of Japanese plant factories.
Early plant plants were mainly research-based, and plant plants that had practical applications were able to produce leafy vegetables, radishes, celery, and mushrooms with lettuce as their main ingredient. In recent years, more and more plant factories have emerged in the form of production operations and demonstration agricultural parks. As of 1997, there were 16 plant factories in operation, with an area of ​​about 1.5h square meters and an annual output of about 550 tons. The main production was lettuce, tomatoes, strawberries, spinach, roses and some tissue culture plants, of which the use of sunlight Type 1h square meters, annual output 287t, fully controlled type 0.5h square meters, annual output 260t. By 2001 it had increased to more than 20 and spread throughout Japan.
With the development of plant factories, related research institutes, organizations and enterprises have been established and related activities have been increasing. For example, the Japan Plant Factory Association holds a nationwide academic conference every year. The Plant Factory Promotion and Popularization Society actively promotes and promotes applications. It also maintains close contact with facilities gardening society, biological environment regulation society, meteorological society, lighting society, and electrical society. To ensure the advanced nature and practicality of its research.
Second, the main technology 1. Hydroponics technology <br> Nutrient solution cultivation methods in Japan, there are many kinds of methods, such as NFT, Zhan Liquor culture, spray culture, solid matrix culture (including rock wool cultivation, gravel culture, sand culture, etc.), Among them, rock wool cultivation and NFT are the main factors, and rock wool cultivation accounts for nearly 50% of the cultivation area of ​​nutrient solution. Typical nutrient cultivating devices are available in the following forms: 1 Three-water NFT device - the cultivation bed is made of foam, with a certain degree of inclination (1/80-1/100), and the bottom nutrient solution is filmy slowly Flow can be automatically fed with fertilizer, and sterilizing device is also provided. 2 Concorde type - using plastic molding cultivation bed, divided into several units, suitable for fruit and vegetable cultivation; 3M type - molding tank made of "U" foam shaped product connection In addition, the planting board is also made of foam, with a polyethylene film inside it, suitable for the cultivation of leafy vegetables, especially duck celery; 4 New-style equal-volume exchanging device - its main feature is that the cultivation tank is divided into two parts. Equivalent exchange of nutrient solution to replenish enough oxygen in the root system (2, 3, and 4 belong to the Zhanye plant); 5 Chenghe type - This is a circulating rock wool plant, installed in the middle of the cultivation tank The drainage pipes, in order from the bottom to the top, lay granular rock wool mats, rock wool blocks and stereotyped irrigation pipes. Drip irrigation is used, and excess nutrient solution flows back to the sump for recycling. In plant factories, mobile planting devices are used mostly, mainly in the form of three-dimensional, three-dimensional, and inclined. Through effective planting, the effective cultivation area is increased.
Japan's nutrient solution theory is very mature. Among them, the formula of the Garden test standard developed by the Xingjin Horticultural Testing Site is versatile and suitable for a variety of vegetables, while Yamazaki Formula is a proprietary formulation for each crop. These two formulations are also widely used in our country, in addition to the God Park formula. Japan's research and application in nutrient solution management, sterilization, recycling, and disease control have also reached a high level. The development of the hydroponic cultivation technology has promoted the improvement of plant factories. Compared with the soil cultivation, the nutrient solution cultivation can accelerate the growth process of the crop and increase the number of cultivated pods in a year by 15%-20%, such as lettuce and celery for one year. Six pods were grown, onion 4.8 茬, cucumber and tomato 1.8 茬.
2. Environmental Control Technology <br> Plant Factory To achieve the goal of annual continuous production, environmental control is an important technology.
(1) Crop growth and its environment. Plant factory as a semi-closed system constantly exchanges material, energy and information with the outside world. The birth of its internal crops is affected and restricted by the following environmental factors: light (light intensity, light quality and length of sunshine), temperature, humidity , CO2 gas concentration, wind speed, and root environmental factors such as pH of nutrient solution, EC, fertilizer composition, dissolved oxygen, liquid temperature, and flow rate. For the optimal control of plant factories, the most fundamental thing is to clarify the relationship between the physiological processes of crop photosynthesis, product accumulation, trans-flow 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 play an independent role in crop fertility, but are the result of comprehensive effects of various factors; second, they control cost issues; The third is that the maximum output does not mean the highest quality.
Recently, research on the effects of physical stimuli such as electromagnetic fields, acoustics, and far-infrared rays on crop reproduction has been particularly noticeable, but the mechanism of its effect is still unclear.
(2) Principles and methods of environmental control. Plant factories, especially fully controlled plant factories, need to consume large amounts of electricity to supplement light and air conditioning in order to control the conditions of light and temperature. The cost of environmental control is very high. At the same time, there is a law of decreasing returns to environmental control, that is, when the control cost increases to a certain extent. Continue to increase, the control effect is getting smaller and smaller. Therefore, it is necessary to comprehensively consider the composite effects of various environmental factors in plant factories. First, it is reasonable to optimize the factors that have low control costs and good effects. This is a commonly used control method and is called the principle of optimality. Using this method, you can use low-cost factors to make up for high-cost factors and achieve better overall control.
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 Networked Control, Optimality, adaptation and intelligent control.
Third, the latest developments <br> In recent years, the Japanese Plant Factory Association journal and related academic conference, published a number of the latest technical reports in this field, focused mainly in the following areas: 1 artificial light technology, including Fluorescent close-range high-efficient intermittent fill light, development of high-pressure sodium lamp super wide-angle lamps, and development of new light sources such as light-emitting diodes LED and laser diode LD; 2 development of nutrient solution sterilization (thermal sterilization, ultraviolet sterilization, ozone sterilization); 3 utilization of images Processing and communication technology for long-distance cultivation management; 4 research of the locking system CELSS; 5 functional pesticide-free vegetables and quality evaluation; 6 plant factory planning and design of virtual technology; 1 use of biotechnology for tissue culture, breeding and genetic research; 8 Informatization, networking and intelligence of cultivation management (expert system, decision support system); development of 9 seedling factories and underground plant factories; 10 monitoring of crop physiological information; 10 plant plant automation technology and Internet technology in plants Factory applications, etc.
IV. Outlook <br> At present, the development of Japanese plant factories has reached a very high level. Research and application in some fields have surpassed those in the developed countries such as the Netherlands and Israel where the greenhouse industry is more developed. However, many technical issues are still in urgent need of solution. In order to promote the industrialization of plant factories and reduce production costs as the core, it is crucial to develop hardware and software technologies.
In the 21st century, plant factories will play an increasingly important role in Japanese agriculture, opening up a new path for solving food problems, environmental problems, and even the development of the universe.