The Solar Greenhouse Climate Suitability Division

Solar greenhouse is a type of facility horticulture invented in northern China and grows popularity rapidly since emerged in1980s. Its vegetable production in cold seasons greatly eased the problem of vegetable supply off-season in China, especially in the northern region. However, the facility horticulture is strongly regional. Its production is heavily dependent on climatic conditions. Although the overall climatic conditions in northern China are superior, various regions have varying degrees of climate suitability of solar greenhouse development due to their differences in climate resources. By the great impact of severe weather such as low temperature, scant sunlight and blizzard, solar greenhouse production is followed by the problems such as high investment, high energy consumption, low and instable economic efficiency. Based on the urgent need of the rapid development of solar greenhouse in northern China in recent years, the problems of facility horticulture climatic zoning and the theory of agro-climatic division, this study regionalized and evaluated the climatic suitability of the solar greenhouse development in this region. The result can provide some reasonable basis for the rational utilization of climate resourses,the scientific layout and the efficient development of solar greenhouse for this region.Firstly, greenhouse-related climate resources in northern China were compared with those in the same latitude regions in the world and their distributions in research area were analyzed. The results showed that solar energy resources in northern China are significantly better than those in the same latitude regions in the world, but it is very different in various regions:the higher the latitude the better light condition; heat resources are also great different from the same latitude regions in the world:much colder in winter, a little heater in summer, and the higher the latitude the more obvious.Secondly, by the use of mathematical statistical methods and while the solar greenhouse development requirements of the climatic conditions were considered, from four aspects of light,temperature,wind and snow,six factors: the total radiation in winter,the number of overcast days in solar greenhouse production season,the average temperature in winter,the annual extreme minimum temperature,the average value of monthly maximum wind velocity in production season,the average value of the annual maximum snow depth, were choosed for suitability assessment indexes and their limit values are determined. In the technical support of GIS, first, climatic suitability zoning for the six single climate index were carried out, then by the use of the sum method of weighting exponent as evaluation method and indexes weights determined by analytic hierarchy process,overlay analysis by the limiting factors of light and temperature, light, temperature and wind, light, temperature and snow, light, temperature, wind and snow were conducted respectively and the comprehensive climate zoning results were obtained which divided the climatic suitability of solar greenhouse development in this region into four grades:the most suitable,suitable,less suitable and unsuitable.The results of the comprehensive zoning showed that the most suitable development area mainly concentrated in the basin of southern Shaanxi; the suitable development area distributed in southern Inner Mongolia Alashan Plateau, western and southern Loess Plateau (including Ningxia, Gansu, Yan’an in northern Shaanxi, Shanxi Linfen, Yuncheng Basin, western Henan)and the North China Plain; the less suitable development area distributed in North Loess Plateau (including the central Inner Mongolia, northern Shaanxi, Northern, northern Hebei plateau);the unsuitable development area included Youyu, wuzhai in northern Shanxi, and some regions in northern Hebei. The results matched with the actual situation overall, which confirmed that the selection of zoning indexes, the limit values and the adoption of zoning method were proper. But there were also a little areas slightly different.Thirdly, Ningxia and eastern Gansu, Henan, Shaanxi with different climatic characteristics in the study area were selected as three typical study areas and more detailed climate suitability zoning were carried out in them respectively. Then some reasonable development suggestions were provided in accordance with the division results, horticultural status quo and the main agro-climatic problems in these regions. Fine zonings in typical study areas, on the one hand, verified the zoning results in the large area, on the other hand, offered more detailed information of the impact of local climate conditions on the development of local solar greenhouse, and were provided with more practical guiding significance in greenhouse production run.Lastly, by the use of historical climate data and solar greenhouse photosynthetic production potential estimation model, the photosynthetic production potential and photoperiod-temperature production potential of crops in northern China solar greenhouse were estimated, and the estimated results were divided and assessed.