| Along with the progress in the art of agriculture and the modernization of farming, facility agriculture quickly blooms in our country. As the main type of facility agriculture, greenhouse is of obvious social and economic benefits and is widely used in our country. Currently the production area (including the solar greenhouse and plastic greenhouse) of greenhouse is up to 1,390,000 hectares in our country, which becomes the number one in the world and reaches a certain scope. The large-scale multi-span plastic greenhouse is a type of greenhouse which appears in the last decade and spreads quickly. Comparing with the glasshouse, it has less weight, its skeleton uses less material, the overshadow efficiency of components is smaller, it costs less, it can be used longer but its ability of controlling environment can reach the same level as the glasshouse' s, therefore, it can be accepted by more people and almost becomes the mainstream of modern greenhouses. Because of the advantage of the natural condition, climatic condition, resource condition, location, economy, and technology etc, China East area mainly develops spring premature vegetable planting and autumn serotinous planting using plastic greenhouses. Since the age of reform and open, the region advantage is more outstanding and with the addition of the growth of city construction and tourism and the needs to adjusting industry structure, the planting area of vegetable extends continuously and the requirement of vegetable production also gets higher and higher. The main environment factors which affect the growth of plants are temperature, humidity, and sunshine etc, but it iswarm at most part of China East area in our country, the warming time is not long in winter, the greenhouse temperature is high in summer and the highest room temperature is often upper than 40℃, so 2/3 of the year we can not plant in greenhouse, which dilapidates the greenhouse over long time. Therefore, the problem of summer greenhouse cooling has become a big problem of developing facility planting in China East area of our country. Developing high-performance, less-consuming greenhouse cooling facility to extend the planting season and improve the greenhouse usage has become the urgent problem, which needs to be solved. Because it is made in a low price and together with window-opening facility and shading or cooling system, east-china type multi-span plastic greenhouse can reduce the high temperature inside the greenhouse in summer at a certain level and is widely used in China East area.At the end of 80' s, the spread of using solar-screen-covering plant and choosing the corresponding high-temperature-resistant variety makes summer serotinous planting, high-temperature planting and early autumn planting success, which highly reduces the short supply of vegetables, especially the supply of foliar vegetables and forms a main feature of vegetable facility planting in China East area. Currently there are mainly 2 types of overshadow screen, indoor shading and outdoor shading. Because it adds a shading layer outside the greenhouse, which prevents most of the sunlight from entering the house, directly reduces the amount of straight and dispersed 1 ights from the air and effectively reduces the radiant heat. Therefore, it gets better utilization. Because of the current increasing of the types of solar screen' s material, reasonably choosing the material of solar screen to achievebetter effect has become a common problem that facility planter faces. In order to make it easier for greenhouse planter to reasonably choose overshadow screen to satisfy different kinds of shining needs and cooling effects, studying the cool ing effect under the solar screen with different material, color and overshadow efficiency turns to be more important.Based on this, four solar screen with different kinds of material, color and overshadow efficiency are set on a typical multi-span plastic greenhouse in China East area, east-china type multi-span plastic greenhouse in this experim...
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