Studies on Forecast Model of Photosynthetic Active Radiation in Sunlight Greenhouse in Winter in Panjin

In order to explore the law of photosynthetic active radiation in winter sunlight greenhouse in Panjin and serve the local facility agriculture better,based on the observed data of sunlight greenhouse microclimate and of the nearby weather station during winter in 2012,the methods of correlation analysis and stepwise regression analysis were adopted to study characteristics of photosynthetic active radiation in sunlight greenhouse and the ratio of photosynthetic active radiation to global radiation under different weather types during winter,and to set up forecast models of photosynthetic active radiation in sunlight greenhouse under different weather types during winter.The results showed that：（1） the daily variation of photosynthetic active radiation in sunlight greenhouse on sunny and cloudy days were both obvious,and photosynthetic active radiation in sunlight greenhouse was 1-38 W/m^2 when it＇s cloudy.（2） ηPARon typical cloudy day was the highest,on cloudy day was secondary and on sunny day was the minimum during winter;（3） the methods of stepwise regression analysis were respectively adopted to set up models of the highest daily maximum photosynthetic active radiation,the total daily photosynthetic active radiation,daily maximum global radiation,and the total daily global radiation in sunlight greenhouse associated with climate outside,the models passed the 0.01 level of significance,and fitting test had been carried out：4 factors were fitted well on sunny and cloudy day,but fitted poor on overcast day.

Technology issues and prevention strategies on sunlight greenhouse vegetable

Energy-saving solar greenhouse vegetables cultivating is to create and improve microclimate environment with greenhouse in those seasons impossible for open cultivation production and in order to achieve the purpose of harvest in advance or in delay. Since a greenhouse needs huge construction expenses and high production costs, only though the improvement of facility utilization can we obtain better economic benefits. Vegetable germination and seedling stage need a long time for ground, so they need smaller standing area. So we concentrated in a small area of cultivation can not only create a suitable environment easily, nurture strong age seedling, but also can avoid greenhouse waste. Make transplanting to greenhouse after Seedlings breeding can effectively reduce the fertility cycle and substantially increase greenhouse utilization.