Abstract: Based on the data observed at 30 agro-meteorological stations in Henan Province that include the phenological development and grain yield components of winter wheat and meteorological elements over the period of 1981-2010, the changes in the length of growing season, the requirement of accumulated temperature, and the yield components of winter wheat were investigated. A total of 196 cultivars of winter wheat were planted during this period. Correlation analysis and regression were used to perform the investigation. The results show that mean temperature in wheat growing season increased significantly. The increase in vegetative period was more pronounced than in reproductive period. In contrast, precipitation did not show significant trends over the 30 years. Cultivar shift and climate warming shortened the length from emergence (E) to heading (H) significantly with the rate of 2.8-5.9 d/10a, but the days from heading to maturity (M) increased significantly with the rates of 1.3-2.5 d/10a. Nevertheless, the accumulated temperature (>0℃) to complete the developmental phases increased, particularly in the H-M phase. The increase rates were 26-50 ℃?d per decade. 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 (>0℃) 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 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 cultivar shift of winter wheat over 1981-2010 in Henan Province was characterized by shortening vegetative period, extending reproductive period and improving the weight of 1000 kernels under climate warming.

Key words: winter wheat, cultivar shift, climate change, Henan Province