Impacts of different grades of drought on winter wheat yield in North China Plain

Abstract: North China Plain is one of the most important crop production bases in China, particularly on the sowing area and winter wheat yield in national food security. Meanwhile, the most serious agro-meteorological disaster, drought has posed a great threat to the yield of winter wheat in this region. Therefore, this study aims to explore the impacts of different drought grades on the yield of winter wheat using the management data of crop, soil, and field. The daily weather data was also collected from 44 meteorological stations in the North China Plain from 1981 to 2017. The crop water deficit index (CWDI) was employed for the agricultural drought. A validated agricultural production systems simulator (APSIM) was utilized to evaluate the effects of different drought grades on the yield and production of winter wheat during growing stages from jointing to flowering date and from flowering to maturity date. The results showed that there was a spatially higher yield reduction rate in the north than the south in the study area when the drought occurred during growing stages from jointing to flowering date, and from flowering to maturity date of winter wheat. Furthermore, the yield reduction rate caused by drought during the growing stage from flowering to maturity date was higher than that during the growing stage from jointing to flowering date (26.8% vs. 19.1%). In addition, the winter wheat yield suffered the most from drought in the Beijing-Tianjin-Hebei region, whereas the least in Henan Province. The yield reduction rate increased significantly, with the increase of drought grades. Specifically, the yield reduction rates under the light, moderate, and severe drought during the stage from flowering to maturity date were 16.5% (3.0%-47.8%), 32.8% (9.9%-54.2%), and 44.9% (11.9%-63.5%), respectively. The yield reduction rates under the light, moderate, and severe drought during the stage from jointing to flowering date were 10.3% (2.1%-25.3%), 18.8% (5.4%-36.0%), and 28.6% (10.6%-45.9%), respectively. Among three regions, the winter wheat yield suffered the most in the Beijing-Tianjin-Hebei region at the same drought level, while suffered the least in Henan province, except for the severe drought during the stage from jointing to flowering date, during which suffered the least in Shandong province. There was also a gradual increase in the effect of different grade droughts on winter wheat production from southwest to northeast actual planting areas. The winter wheat production in Shandong province suffered the most from the severe drought during growing stages from jointing to flowering date and from flowering to maturity date of winter wheat, but the least in Henan province in practice. The total yield suffered the least in the Beijing-Tianjin-Hebei region. In the case of light and moderate drought during the growing stage from jointing to flowering date, the most effect in the Beijing-Tianjin-Hebei region, and the least effect in Henan province. In the case of light and moderate drought during the growing stage from flowering to maturity date, the most effect was shown in Shandong province, while the least effect in Henan province.