Characteristic Of Winter Wheat Cultivar Shift In Henan Province Under Climate Change

World’s climate has clearly warmed over the past five decades. The temperature has increased by 1.2℃ since 1960 in China. China’s average temperature is estimated to increase further by 1-5℃ by 2100. Agricultural production is closely related to climate change. Increased temperature is one of the most important factors for the impact of climate change on crop yield. Wheat is the second important food crop in China. Wheat production is closely related to food security, and occupies an important position in the national economy. The planting area and yield of wheat in north China plain respectively occupied 47% and 56% of China. Average planting area of wheat in Henan province has reached nearly 5 million hm2 in recent ten years, occupying 22% of the total wheat planting area and 27% of the total yield of China. There have been 126 new varieties of wheat bred and approved in Henan from 1986 to 2005, which greatly contributed to the improvement of wheat yield.Based on the data observed in 30 agro-meteorological stations in Henan Province that include the phenological development and grain yield components of winter wheat and climate over the period of 1981-2010, and the indexes of new winter wheat varieties over the period of 1960-2005, we investigated changes in length of growing season, the requirement of accumulated temperature, the yield components of winter wheat in this province, and the agricultural dynamics of new winter wheat varieties. Correlation analysis and regression were used to perform the investigation. Assessment of winter wheat cultivar shift characteristic, the impact and adaptation of climate change on wheat production in Henan province is helpful to provide a scientific evidence for the variety improving to adapt climate warmingMajor results presented as follows:1. The results show that mean temperature in wheat growing season increased significantly. The increase in vegetative period was more pronounced than in reproductive period. Sunshine duration decreased significantly, and the decrease in vegetative period was more pronounced than in reproductive period. In contrast, precipitation did not show significant trends over the thirty years. The increase of mean temperature in wheat growing season made the most impact on yield components. Cultivar shift and warming shortened the length from emergence (E) to heading (H) significantly with the rates of 2.8-5.9d/10a, but the days from heading to maturity (M) increased significantly with the rates of 1.3-2.5d/10a. Nevertheless, the accumulated temperature (>0 ℃) to complete the developmental phases increased, particularly in the H-M phase. The increase rates were 26-50 degree-days per 10-year. The weight of 1000 kernels increased markedly with the extended H-M phase. However, the spikes and kernels per spike were correlated neither with the length nor with the accumulated temperature in the phase of E-M. A further investigation indicated that both the ratios of H-M to E-M in days and in accumulated temperature in southern Henan, and the ratio of H-M to E-M in days in central and northern Henan increased with the passage of time. The variability of grain yield in southern Henan was better explained by the ratio in accumulated temperature than in days. In central and northern Henan, the grain yield was positively correlated with the ratio of H-M to E-M in days. The shift of winter wheat cultivar over the last thirty years in Henan Province was characterized by shortening vegetative period, extending reproductive period and improving 1000-kernel weight under climate warming2. The main agronomic traits evolvement feature of winter wheat cultivars in Henan Province from 1960 to 2005 presented as follows:The height of winter wheat got lower with a average reduction 5.1 cm/10a. Suitable sowing period was between October 7 (±2d) and October 20 (±4d). The earliest sowing period did not show significant trends. In contrast, the latest sowing period got later with the cultivar breeding years. The whole growth period and accumulated temperature (>0℃) did not show significant trends. The whole growth period of new winter wheat cultivars got shorten gradually after 1980s. The accumulated temperature (>0℃) showed a significant increasing trend from the late 1980s to the beginning of 21st century with a rate of 149.2℃d/10a. Besides, the theorical yield, spikes, kernels per spike and the weight of 1000 kernels of new winter wheat cultivars all significantly increased at a speed respectively of 0.27t/hm2、2.4×105 spike/hm2,1.2 kernel/spike and 1.5g every 10 years, in which the weight of 1000 kernels got the most significant increase and reached a extremely significant level, indicating that it was the biggest contributor among three production elements. As to the difference of winer□ spring characteristic of new winter wheat cultivars, winterness of semi-winter wheat variety was stronger and springness was reduced. Semi-winter wheat varieties increased yield by the improvement of kernels per spike and the weight of 1000 kernels, while spring wheat varieties mainly by increasing spike and the weight of 1000 kernels.