Study on Northern Boundary of Winter Wheat in Liaoning Province

Based on geographic planting data of winter wheat during 1991～1999 and meteorological data, the climatic northern boundary of winter wheat in Liaoning province was studied systematically The accumulated temperature before overwintering was the key climate factor influenced the cropping of winter wheat by the analysis of grey correlation The northern boundary of winter wheat in Liaoning province in the rate of 80% climatic guarantee was obtained by analysis of the accumulated temperature before overwintering The results were verified by using the indices of the negative ground temperature