Abstract: The meteorological data inside and outside the standard plastic greenhouse was collected during the winter period of 2010-2012 in Hangzhou Based on these data, we studied the air temperature variations inside single covered and double covered plastic greenhouse, under the three weather types including sunny, cloudy and overcast And a forecast model of daily minimum temperature inside plastic greenhouse was established by applying the stepwise regression method, verified by model fitting and forecast test The results showed that the change trend of air temperature inside singlecovered greenhouse was nearly the same as that inside double covered greenhouse The diurnal variation of the air temperature was drastic in sunny and cloudy day, but was mild in rain day Under sunny and cloudy day, daily minimum temperature inside greenhouse was less than that under overcast day, so the cold damage was prone to appearing Inside single covered and double covered greenhouse, its daily minimum temperature was 20℃ and 30℃ higher than that of outside, respectively The fitting result of the forecast model indicated that root mean square error (RMSE) between simulated values and measured values was lower than 1.0℃and 0.5℃, for single covered greenhouse and double covered greenhouse, respectively As to single covered greenhouse, the RMSE was 0.5℃,1.3℃ and 0.7℃, respectively under sunny, cloudy and overcast day, and the RMSE was 0.4℃,0.3℃ and 0.5℃ for double covered greenhouse Furthermore, the result of the forecast test illustrated that the RMSE between forecast values and measured values of daily minimum temperature was less than 20℃ and 10℃, respectively for single covered greenhouse and double covered greenhouse The results of model fitting and forecast test showed that forecast model had high accurate and good practicability

Key words: Plastic greenhouse, Double film, Air temperature, Daily minimum temperature, Forecast mode