Brief introduction to the development of greenhouse film in China

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The greenhouse film mulching cultivation technology in China has been applied since the late 1950s s. At first, it was a small plastic arch shed. In 1969, a plastic greenhouse appeared. In 1980s, the greenhouse film began to replace glass in a large area as a transparent covering material for the greenhouse. According to incomplete statistics, 1985- 1986 of national facilities horticulture area for 6. 80 thousand hectares, 1995-It reached 69 in 1996. 910 thousand hectares, 1999--In 2000, it reached more than 1. 6 million hectares. At present, the annual usage of various greenhouse films in the country is more than 1. 4 million t.

(1) Solar greenhouses

The total area of solar greenhouses in China is 380 thousand hectares, of which about 250 thousand hectares are efficient and energy-saving solar greenhouses-10- Under the severe cold condition of 20℃, warm vegetables can be produced without heating. Most of the solar greenhouses are produced in winter, using polyvinyl chloride (pvc)No drop film or polyethylene (PE)Multifunctional composite membrane; In spring and autumn production, PE ordinary film is used to reduce the covering cost, and the thickness of the film is mostly 80-120t muBetween m. In recent years, the newly developed EVA multi-functional composite film has significantly better comprehensive performance than PVC drop-free film and PE multi-functional composite film, and is the agricultural functional film that will be developed in the future.

(2) Plastic large and medium-sized shed

at present, the plastic large and medium-sized shed in our country is about 550 thousand hectares, which is widely distributed, mostly in the middle and lower reaches of the Yangtze River and Huanghuai region. In the past, ordinary shed film was mainly used, since the late 1980s S, PE multifunctional film has been widely used. The thickness of the film used for covering large and medium-sized sheds is 60-60 in Jiangnan and Jianghuai areas-80/μ M, North China, northeast and northwest regions are mostly 100-120 muM. In recent years, EVA multifunctional composite membrane with low VA content has also been used in large and medium-sized plastic sheds and has shown broad application prospects.

(3) Plastic small arch shed

plastic small arch shed is widely distributed in our country with various structural forms. It is the fastest growing and largest simple facility in facility gardening, and now it is about 700 thousand hectares. The transparent covering material of the small arch shed is mainly ordinary PE and PVC film with a thickness of 30-Between 50grn. In recent years, EVA thermal insulation film with low VA content is very popular as covering material for small arch shed. In addition to the above-mentioned horticultural facilities, there are about 5 million hectares of modern multi-span greenhouses in our country, a considerable part of which are imported from abroad in recent years and mostly made of plastic film as transparent covering material.