[Yield reduction risk based on WOFOST model and water stress for winter wheat in Henan Province, China]

The main wheat production area in Henan Province was classified into five regions based on observed wheat production data, historical meteorological data and soil data from thirty sites du-ring 1981 to 2014. The changes in the risk of yield loss of winter wheat under water stress condition in each region were calculated with WOFOST model. From 1981 to 2014, the yield reduction rate of winter wheat showed an increasing trend at all the sites with the increase rate of 2.8%-5.0% per 10 years. The yield reduction rate decreased from north to south in Henan Province. The event of yield reduction rate over 20% occurred about once every 10 years in southern Henan Province, and once every 2 years at Xinxiang, Fengqiu and Puyang in northern Henan Province. The event of yield reduction rate over 50% occurred about once every 3 years at Xinxiang and Zhengzhou but was rare in southern Henan Province. The highest hazard areas were mainly distributed in north and middle parts of Henan Province, the lowest hazard areas were distributed at Lushi in western Henan Pro-vince, Nanyang in southwestern Henan Province, Xinyang in southern Henan Province and south part of Zhumadian, the medium hazard areas were distributed in the other regions of Henan Province.