History Of Polytunnel Greenhouses

With the production of high molecular polymers - polyvinyl chloride and polyethylene, plastic films are widely used in agriculture. In the early 1950s, Japan and European and American countries successfully applied film to cover hotbeds, and then covered sheds and greenhouses with good results. my country introduced polyvinyl chloride agricultural film in the autumn of 1955. It was first used in Beijing to cover vegetables in small sheds, and achieved the effect of early maturity and increased yield. In 1957, it was popularized and used from Beijing to Tianjin, Shenyang, Northeast China, Taiyuan and other places, and was welcomed by all places. In 1958, my country had been able to produce agricultural polyethylene film by itself, so the production of vegetables covered by sheds was very extensive. In the mid-1960s, the shed has been shaped into an arch, about 1 meter high and 1.5-2.0 meters wide, so it is called a small arch shed. Since the shed is short and unsuitable for application in the cold and cool areas of Northeast China, in 1966, the small arch shed was first converted into a 2-meter-high square shed in the suburbs of Changchun City. However, it collapsed due to its poor snow resistance. After many attempts at reconstruction, an arched greenhouse with a height of about 2 meters, a width of 15 meters and an area of 1 mu was finally created. In 1970, it was promoted to all parts of the north. In 1975, 1976 and 1978, the "National Plastic Greenhouse Vegetable Production Research Cooperation Association" meeting was held for three consecutive times, which played a role in promoting the development of greenhouse production. In 1976, 29 kinds of greenhouses of different specifications were built in the suburbs of Taiyuan City, which provided rich experience for the structure and construction scale of the greenhouses. In 1978, greenhouse production has been extended to all parts of the south, and the area of greenhouses nationwide has reached 100,000 mu. So far, the national greenhouse area has basically stabilized at more than 100,000 mu. Among them, there are about 70,000 mu in the provinces and cities in the arid regions of northern my country. It is expected that during the "Seventh Five-Year Plan" period, the area of greenhouse cultivation will grow to about 200,000 mu. The material covered by the greenhouse is plastic film. It is suitable for large area coverage because of its light weight, good light transmission and thermal insulation performance, strong plasticity and low price. And because the lightweight skeleton material can be used, it is easy to build and shape, and can be selected on the spot, the construction investment is less, and the economic benefit is higher. And it can resist natural disasters, prevent cold and heat preservation, resist drought and waterlogging, cultivate early, delay cultivation, prolong the growth period of crops, achieve the purpose of early maturity, late maturity, increase and stable yield, and is very popular among producers. Therefore, it has developed rapidly in the arid regions of northern my country.

The greenhouse was originally a special equipment for vegetable production. With the development of production, the application of the greenhouse has become more and more extensive. At present, greenhouses have been used for potted and cut flower cultivation; fruit tree production is used for cultivating grapes, strawberries, watermelons, melons, peaches and citrus, etc.; forestry production is used for tree seedlings, ornamental trees cultivation, etc.; aquaculture is used for sericulture, breeding Chickens, cattle, pigs, fish and fry, etc. The scope of application of greenhouses is still under development. Especially in alpine regions, sandy and arid regions, it plays an important role in resisting low temperature drought and sandstorm hazards. Countries around the world have successively built plastic greenhouses in order to develop agricultural production. In the late 1970s, the largest plastic greenhouse in Japan was 10-20 hectares. The total land area of the Almerili region of Spain is 315 square kilometers. It is a dry area. In order to develop vegetable production, it covers 120 square kilometers of greenhouses, which is the largest greenhouse in the world.