Abstract:

In the recent 50 years, last day with the temperature ≥0℃, the accumulate temperature of ≥0℃ before Over wintering and monthly mean temperature form October to December changed with big annual fluctuation and the tendency of liner growth of was not obvious .However, In the recent 5 years, last day with the temperature ≥0℃ has been reduced obviously. the accumulate temperature of ≥0℃ before Over wintering increased largely and the monthly mean temperature form October to December was higher. The wavelet analysis indicated last day with the temperature ≥0℃ had mainly the interannual oscillation periods of 4-7 years and 14-17years.and the accumulate temperature of ≥0 before Over wintering had mainly the interannual oscillation periods of 5-10 years and 15-20years. the accumulate temperature of ≥0℃ before Over wintering seems to be increasing for large scale period. Monthly mean temperature form October to December had mainly the interannual oscillation periods of 3-5 years,8-10years and 20-25years and the coming 8-10 years is in the stage that mean temperature would has been higher. The obtained results showed that thermal resource of winter wheat the growth period before over wintering showed an increasing trend and these agrometeorological elements fluctuated in a big way greatly. Therefore, appropriate readjustment should be made on sowings time based on mid long climate prediction avoid affecting on winter wheat growth and development by interannual fluctuation of thermal resource.