I. Solar greenhouse facilities Agriculture and its key technologies The growth and development of crops depends on the genetic characteristics of the crops on the one hand and the external environmental conditions on the other. Solar greenhouse facilities Agriculture is a modern agricultural technology that uses a specific solar greenhouse facility to create an artificial microclimate environment suitable for the growth and development of crops in seasons or regions where crops are not suitable for open cultivation, thereby increasing production and income. The regulation of the artificial environment in solar greenhouse facilities is a key technology. First of all, we analyze the impact of environmental parameters such as temperature and humidity and CO2 concentration on crops from the perspective of plant growth and development. (1) Temperature, temperature and light are the two most important factors in the growth and development of plants. The suitable temperature for the main fruits and vegetables is 23°C to 28°C during the day and 12°C to 18°C ​​at night. The suitable temperature for leafy vegetables is 15°C to 20°C during the day and 5°C to 8°C during the night. Even if it is the same vegetable crop, its fertility temperature is not exactly the same. When the ambient temperature exceeds the appropriate fertility temperature of vegetables, it will cause delayed fertility and often affect the development of buds. Taking tomato as an example, the effect of high temperature on the buds of tomato differs depending on the stage of development. The early stage of flower bud differentiation is tolerant to high temperatures, and the ability to withstand high temperatures is reduced. The meiosis at 9 to 10 days before flowering is the least resistant to high temperatures. After fruiting, the young fruit is fertilized. The high temperature resistance gradually increases. Due to the continuous flowering of tomato, continuous results, different levels of buds, flowers, young fruit in different developmental stages, so require sophisticated temperature control. Other vegetables are similar. Low temperature will reduce the photosynthetic rate of the leaves of vegetables, and also delay fertility, reduce the quality of fruits and vegetables, and increase the number of malformed fruits. The lower the temperature, the longer the duration of low temperature and the more significant the delay of fertility. When encountering low temperatures to suppress fertility, the greenhouse is generally closed and the ground temperature is increased to accumulate heat. At high temperatures, fertility disorders can occur. In the case of low temperatures during the night and high temperatures during the day, fertility is increasingly suppressed. Therefore, there is absolutely no mutual compensatory effect between the low temperature and high temperature that exceed the suitable fertility temperature. For vegetable crops, variable temperature control is currently the ideal measure. Through variable temperature control throughout the day, the crops undergo vigorous photosynthesis during the day and promote the transfer of photosynthetic products after sunset, and minimize respiratory depletion to increase yield. On sunny days, suitable photosynthetic temperature should be maintained after sunrise during the day. After a few hours, when the temperature exceeds the limit temperature, ventilation and ventilation should be performed in time to prevent high temperature obstacles. After the evening, the indoor temperature dropped sharply, and the temperature should be maintained for a few hours in the first half of the night to promote the transfer of photosynthetic products. The respiratory consumption should be suppressed when the temperature is lowered to lower temperatures in the middle of the night. This can greatly increase the yield of vegetables. (2) Carbon dioxide Carbon dioxide is one of the main raw materials for photosynthesis of green plants. The supply of carbon dioxide in the ecological environment directly affects photosynthetic rate, yield, and quality. Increasing the concentration of carbon dioxide can increase the individual weight of fruit and vegetables and shorten the cycle of vegetable production. Tests have shown that when the concentration of carbon dioxide in the environment is 2 to 3 times higher than the concentration of carbon dioxide in the atmosphere, the yield of most vegetables (eg, cucumbers, tomatoes, etc.) can be doubled. The variation of indoor CO2 concentration: At night, CO2 is released due to the respiration of crops, so that the concentration of indoor CO2 is higher than in the natural world; after sunrise, as light enters the room, crop photosynthesis consumes part of the CO2, which causes the indoor CO2 concentration to drastically drop. Carbon dioxide concentration in nature. If no measures are taken, despite the photosynthetic temperature conditions meeting the requirements, carbon dioxide deficiency will also occur in this closed facility and affect photosynthesis. (3) Humidity If it is not extremely dry or wet, the growth of the crop is not affected by the humidity, and the stomata of the leaves can be freely opened and closed to adjust the transpiration. However, under conditions of continuous drying, the stomata of the leaves are closed, affecting photosynthesis and inhibiting fertility. Extremely too humid conditions are encountered during the flowering period of fruit and vegetables, pollen cannot fully spread out, and pollen tube extension is blocked, resulting in malformed fruit. If vegetable production is carried out under closed or semi-closed conditions, most of the water vapor condensate produced by ground evaporation and crop transpiration will stay in the room, making the relative humidity and absolute humidity of the air significantly higher than the outside world. When the temperature drops in the evening, the humidity will be over-saturated and produce fog. The higher the soil moisture is, the lower the room temperature is, and the longer the fog is, the greater the concentration is. The mist condenses on the film into droplets of water, wetting the stems and leaves of the crop, and the moist pathogenic bacteria invade the pores with the water droplets. Humidity is the main factor affecting the occurrence of plant diseases and pests in facilities. High humidity coupled with suitable temperature conditions will accelerate the occurrence of pests and diseases. From the above analysis, we can know that the yield, quality, production cycle, and occurrence of pests and diseases of vegetables are closely related to the greenhouse environment and should be controlled and adjusted scientifically and reasonably. II. Introduction of solar greenhouse facilities in China At present, Shanghai, Beijing and other regions have introduced modern solar greenhouses and key technologies from Israel, France, the Netherlands, and other countries. Taking Sunqiao in Pudong, Shanghai as an example, the application of high-tech modern agricultural technology has not only improved the utilization of solar energy and land, but also created a good environment for plant growth, increased the yield and quality of crops, and produced huge economic benefits. The production of up to 250,000 to 30,000 kilograms is 10 times that of the open field and 6 times the output of the greenhouse. Here is a brief introduction to the two sets of greenhouse equipment imported from Israel and France. (1) Greenhouse frame materials Israel: Made of galvanized steel pipes, protective measures have been taken to prevent corrosion. France: Made of hot-dip galvanized steel pipe, the plastic film is fixed by clips made of steel and hard PVC. (2) Cover Material Israel: The braided composite polyethylene film SOLARIG has a transmission ratio of 80% and is poor, but it has high mechanical strength, good tensile and impact resistance, long life, and contains additives. The main function of the additive is absorption of infrared rays and anti-ultraviolet rays; there is also an anti-frosting additive that can prevent dew condensation on the film. The film has a heat exchange coefficient of 470 W/m 2 °C and a thickness of 200 μm. France: The top cover material is a triple-pressed PVC film with a thickness of 200 μm. It is colorless and contains anti-cracking additives. It is used in the harsh climate of southern France and has a life expectancy of 45 months. The gable and side wall covering materials use double inflatable plastic film with a thickness of 200 μm. (3) Automatic environmental control in Israel: The microcomputer can collect and store temperature and humidity data inside and outside the greenhouse 24 hours a day. It can perform data analysis of the relevant climatic conditions in the geographical area, and can change operating procedures by introducing new data. Can control the side of the roller blinds, thermal screen shade system (heat screen in the crop above the height of 3 ~ 5m, when the expansion of the ceiling can be formed to cover the entire greenhouse, expand the width of more than 4m, when the width of the collapse to only reduce 10cm, heat screen with all accessories, pulleys, cables, nylon ropes, receivers and couplings), heating system and hot water pump. Can monitor temperature and relative humidity, with alarm function, system fault indication, etc. It can control the flow valve and fertilizer supply pump in the crop area in irrigation and fertilizer irrigation. France: The microcomputer can control greenhouse temperature, incident sunlight intensity, wind power, water spray volume, and humidity according to user instructions. Top ventilation, 50% open. Third, the development of China's solar energy greenhouse facilities, the introduction of foreign advanced technology, after digestion and absorption, China has initially had the conditions for the development of solar energy greenhouse facilities, we should vigorously promote and actively promote. (1) Galvanized steel pipes for structural frameworks with anti-corrosion properties are available on the domestic market and are reasonably priced. Localization is no longer a problem. (2) The domestic polyvinyl chloride film used for covering has only been used for 4 to 6 months before, and the heat-retaining property, dripability, etc. cannot meet the production needs. Now, a variety of new materials have been developed, and improvements have been made in technology: adding anti-aging agents to extend the service life; adding infrared resistors to the masterbatch to improve the insulation performance; adding a trickle aid, Made of heterogeneous multi-layer composite membrane, enhanced the drip effect; a small amount of UV photoresist was added to the masterbatch, reducing the incidence of crops; adding a monochromatic additive, made a diffuse reflective film, dimming film, so that The light distribution in the greenhouse is more even. Therefore, the localization of solar greenhouse covering materials can also be realized. (3) In winter, solar greenhouses require hot water heating; in summer, greenhouses need to spray water, spray white, and use a shade net. The automatic control technology of these operations has been fully matured in China. White spray material has been successfully developed and put into the market. The sampling of temperature and humidity involved in the microcomputer is a routine problem of sampling thermal parameters. Fertilizer supply pumps, ventilators, and hot water pumps can all be controlled by microcomputers. Flow valves, side shutter doors, and hot screen shade systems in irrigation and fertigation crop areas can be controlled by the microcomputer analog output to control the electric actuators. There is already a ready-made electric actuator product in China. Only the material of the rolling shutter door and the hot screen shading system and the actuator that rolls up from the electric actuator to the rolling shutter door and the hot screen shading system need to be developed. The alarm and system fault analysis functions are achieved by sampling the system temperature and humidity data, system operating part state parameters, and empirical data and accumulated data analysis software already existing in the microcomputer. (4) Carbon dioxide fertilization can be achieved using gas storage vaporization gas storage technology. The service is now available on the market and the gas concentration is controlled by computer control. (5) When the lighting, temperature, and humidity control hardware described above are implemented, the software can be used to intelligently adjust the production process of each crop to grow it in the best condition. Now this software has been developed in China. In our country, suitable for the operation of the local characteristics of the greenhouse is the necessary conditions for the promotion of solar energy greenhouse facilities, it is particularly worth mentioning that China is a vast territory, regional climate conditions are very different, the economic conditions are also very uneven, from the regional features should be strong Develop solar greenhouses with three types of climate characteristics in the middle and lower reaches of the Yangtze River, the Pearl River Delta, and the north.
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