Distribution Characteristics of Winter Wheat Yield and Its Influenced Factors in North China

Abstract

APSIM-Wheat model was validated in regional level with crop data from agrometeorological observation stations in North China. Combining the daily climatic data during 1961–2007, the spatiotemporal distribution characteristics were analyzed in potential yield, water-restricted yield, and water-nitrogen-restricted yield of winter wheat to understand the influences of climatic factors on potential yield in different levels. The APSIM-Wheat model was proved to be applicable in North China. In the region, the potential yields of winter wheat in different levels showed a zonal distribution in space with a generally temporal decline; however, the differences of spatial distribution characteristics were distinct among yield levels. The decreasing trends were from northeast to southwest in potential yield of winter wheat, from southeast to northwest in water restricted yield, and from west to east before a decreasing from east to west in water and nitrogen restricted yield, with the maximum values in Jining, Shandong Province. Hebei Province was located in the zone of high values of potential yield and water and nitrogen restricted yield but low value of water restricted yield, where irrigation was the main factor to improve the yield of winter wheat. Shandong Province was in the zone of high values of potential yield and water restricted yield but low value of water and nitrogen restricted yield, where nitrogen fertilizer was the main factor to improve the yield of winter wheat. Henan Province was a zone of low value of potential yield, where radiation was a main restraint. The total radiation during the growing season was a major climatic factor that determined the spatiotemporal distribution characteristics of the simulated potential yield of winter wheat, and it was positively correlated with the potential yield (P < 0.01). Precipitation during the growing season was the most important climatic factor for distribution characteristics of water restricted yield, which was positively correlated with water restricted yield (P < 0.01). In contrast, the variance of water and nitrogen restricted yield explained by climate factors was only 0.48, suggesting that soil factors were determinative rather than climatic factors. Under the background of changed climate and unchanged varieties of winter wheat, the potential yields at different levels showed declining trends which resulted from the decrease of radiation and the increase of accumulated temperature during wheat growing season. The primary climatic factors for determining the distribution characteristics of winter wheat yield were total radiation and precipitation.