Correspondence and Shifting Analysis for the Winter Wheat Growing Period before Winter and Solar Terms in the North China Plain under Climate Change Background
Based on the 1961-2017 surface data from 55 meteorological stations in the winter wheat planting area of North China Plain, the accumulated temperature required for winter wheat wintering period was selected as the index to analyze the spatial and temporal distribution and variation characteristics of the solar terms of wintering period and sowing period. This study have used the longevity formula and the method of climatic tendency rate. The correspondence and deviation between winter wheat related agricultural activities and solar terms were also discussed. The wintering period of winter wheat in North China showed a trend of significant delay (P<0.05) in recent 57 years. It was delayed by about 3.7 days. The solar term of the sowing time for winter wheat in North China Plain is gradually postponed from north to south. Compared with P1 period (1961-1990), the boundary of sowing period of winter wheat in P2 period (1991-2017) moved northward significantly. Under the background of climate change, there is a certain deviation between winter wheat farming activities and 24 solar terms in North China Plain. The proverbs used to guide farming activities in some areas are no longer fully applicable. For example, the termination day of optimal sowing date of winter wheat in central Shandong Province was postponed from the third pentad of the Autumn Equinox to the first pentad of the Cold Dews. The latest sowing date of winter wheat in northern Henan Province was postponed from the third pentad of the Cold Dews to the first pentad of Hoar-frost Falls.In this paper, agricultural activities were adjusted by studying the corresponding relationship between 24 solar terms and sowing date of winter wheat. In the future, we need to consider the effects of natural factors such as light, water and agronomic measures during the growth period of winter wheat, and scientifically guide agricultural production to adapt to climate change.