Determination of Optimum Sowing Date of Winter Wheat in Suzhou under Global Warming

Climatic variation during winter wheat seeding to overwintering in Suzhou was analyzed by using tendency rate of linear variation,moving average method and mathematical statistics based on the observed meteorological data from 1954 to 2007.The results showed that the average daily temperature in regular seeding season increased at the rate of 0.4 ℃·10y-1(P0.01).The date of average daily temperature ≥16℃ in autumn,which was optimum temperature for winter wheat seeding,was delayed.The active accumulated temperature from regular seeding season to overwintering increased significantly(P0.01).The optimum seeding time for winter wheat postponed to 15-25 October,delayed 7-8 days than regular time with climate warming.Which was help to prevent prosperous grow before winter.