Study on the Change Character of Double Rice Cold Damage in Hunan and Hubei Province during the Past 50 Years

Based on the meteorological data of representative meteorological stations in Hunan and Hubei from 1961 to 2008 years,the change character of double rice cold damage under the background of climate change were analyzed adopting 30 years glide accumulation method.The analysis showed that the 30 years sliding cumulative days of mild low-temperature during spring sowing in Hunan and Hubei were decreased in the recent 50 years,as well as the 30 years sliding cumulative days of moderate low-temperature in central south Hubei,northern and western Hunan.However,there was an increase in southern Hunan,so was the 30 years sliding cumulative days of severe low-temperature.The 30 years sliding cumulative days of mild low-temperature in May reduced in Hunan and Hubei.Instead,that of moderate low-temperature in May in central south Hubei was on the rise,and it was opposite in northern and southern Hunan,but there was no obvious change in western Hunan.The 30 years sliding cumulative days of severe low-temperature showed a decreasing tendency in May in central south Hubei,northern and western Hunan,and southern Hunan showed a contrary tendency.The 30 years sliding cumulative days of mild cold dew wind in Hunan and Hubei were decreased,that of moderate cold dew wind in central south Hubei,northern and western Hunan had the same tendency,but there was a contrary tendency in southern Hunan.The 30 years sliding cumulative days of severe cold dew wind was decreased in central south Hubei and increased in western Hunan,without cold dew wind in northern and southern Hunan.

Analysis of Variation Characters and Prediction Model of Soil Temperature in Solar Greenhouse

[Objective] The aim was to study the soil temperature changes and its forecast model in greenhouse by solar heat. [Method] Annual and daily variation characters of soil temperature were analyzed in this paper by using the observation data of air temperature out of solar greenhouse and different layers soil temperature in it. The soil temperature (daily maximum, daily minimum and daily mean) forecasting models were also studied. Simulation and test were conducted to the forecast model of soil temperature in the greenhouse. [Result] The annual changes and daily changes of soil temperature of each layer in the greenhouse were in single peak curve. The lower layer temperature changes were smaller than the upper layer. The soil temperature of each layer within the greenhouse was closely related to the relevance of same type temperature outside the greenhouse of the day. Taking the average daily temperature, daily maximum temperature and daily lowest temperature of the day and the day before as forecast factors, soil temperature forecast model of different layer of same type within greenhouse was constructed. The simulation outcome of average daily temperature of each layer within the greenhouse was better than the simulation outcome of highest temperature of corresponding layer, worse than the simulation of lowest temperature of corresponding layer. The highest temperature of lower soil and daily temperature of soil were better than the upper layer. The simulated soil temperature was much more close to the observation when the observation was during 15-30 ℃. In other interval, it was lower than the observation. [Conclusion] The study offered theoretical reference for the growth environment of sunlight greenhouse plantation.