Analysis of how dry-hot wind hazard has changed for winter wheat in the Huang-huai-hai plain

Abstract. Climate change is exerting significant impacts on global agricultural production. Climatic variations adversely affect crop production and, thus tend to impose a key constraint of agricultural production, primarily on how to cont inuously enhance the winter wheat yields worldwide. The high uncertainties in predicting the effects of climate change on wheat production are most likely due to rare understanding on the responses of wheat production to extreme climatic factors, e.g. high temperatures, low humidity as well as high wind speed. Dry-hot wind hazard represents one of the main natural disasters for Chinese winter wheat production, especially for the Huang-huai-hai plain. However, high uncertainties of the effects of dry-hot wind hazard on winter wheat production still exist, mainly due to the gaps of long-term observations. Therefore, we selected Shangqiu as the case study area to determine the occurrence regularity of dry-hot wind hazard on winter wheat production in Huang-huai-hai plain. We analyzed regional meteorological data with daily resolution in the later growth stage of winter wheat during the period of 1963 to 2012. In accordance with the meteorological industry standards of “Disaster Grade of Dry-hot Wind for Wheat” by the China Meteorological Administration, we synthesized analyzed the distribution of annual average days of dry-hot wind in winter wheat growing seasons and the associated responses to the climate change. Hence the relationships between dry-hot wind times and winter wheat yields were also discussed. The results showed that the annual average days of light and severe dry-hot wind exhibited tended to decline in the recent 50 years. Great inter-annual variations of light and severe dry-hot wind were observed. The significant inter-annual variations were related with the corresponding meteorological conditions of temperature, moisture and wind speed. The most serious damages of light and severe dry-hot wind both occurred in 1960s while the damages appeared less in the 1980s and the last decade, which could be also explained by the corresponding temperature, moisture and wind speed conditions. From 1963 to 2012, a climatic mutation point of daily maximum temperature was found near 1972, but insignificantly (p>0.05). The wind speed at 2:00 pm and the relative humidity at 2:00 pm were closely related to the hazard conspicuously. A climatic mutation point of the wind speed at 2:00 pm was found near 1984, and climatic mutation of the relative humidity at 2:00 pm was found near 1981 (p<0.05). Daily maximum temperature, wind speed at 2:00 pm and the relative humidity at 2:00 pm played a major role in decreasing trend of dry-hot wind disaster, and the significantly decreased of wind speed at 2:00 pm constituted a main factor in Shangqiu. Dry-hot wind hazard is very sensitive to climate change. Yields of winter wheat were negatively correlated with annual average days of dry-hot wind in Shangqiu (p<0.05). In actual practices, great concerns should be paid on the defense of dry-hot wind for winter wheat production. Thus the most effective practices have to be taken for enhancing the resistance of winter wheat to dry-hot wind hazard through improving filed microclimate condition.