Regional Differences of Winter Wheat Phenophase and Grain Yields Response to Global Warming in the Huang-Huai-Hai Plain in China Since 1980s

The Huang-Huai-Hai (3H) Plain is one of the most important winter wheat production areas in China. In this paper, the relationship between climate factors, growth duration and yield of winter wheat from 1980 to 2013 in the 3H Plain was examined to reveal the responses of winter wheat growth duration and yield to global warming. The results showed that daily average, maximum and minimum air temperatures during the winter wheat growing season increased by 0.43, 0.35 and 0.54 degrees C every 10 years, respectively, on average across the whole region in the past 30 years, although temperatures varied with different spatial distributions. Historical changes in winter wheat phenology have been observed across the 3H Plain since 1990s in that the vegetative growth period of winter wheat shortened by 4.6 days, the reproductive growth period increased by 1.8 days and the whole growth period was shortened by 2.9 days per 10-year period. The changes in the growth period were significantly negatively correlated with minimum temperature increases. The 1 degrees C minimum temperature increase shortened the vegetative growth period of winter wheat by 4.5 days. Accounting for agricultural technical improvement and other non-climatic factors, an average temperature increase of 1 degrees C enhanced winter wheat yield by 2.1% in the northern plain and decreased yield by 4.0% in the southern plain. We found an average temperature during the winter wheat growth season of 8.6 degrees C as the yield variation threshold, and the yield would decrease above this threshold in this region.