| With the increasing global warming,extreme drought events have caused many adverse effects on agricultural production and society.Henan Province is the central production area of summer corn in China.The stability of summer corn yield in this region is of great significance to the national food security.However,in recent years,the occurrence of extreme drought in the growing season of summer maize has increased.It is of great significance for agricultural production science to deal with climate change and prevent the occurrence of drought to assess the risk of extreme drought and analyze the possible impact of extreme drought on the yield of summer maize.According to the extreme drought index(maximum consecutive days without precipitation,CDD)recommended by the World Meteorological Organization(WMO),the spatial and temporal distribution characteristics of extreme drought in summer in Henan Province in recent 48 years were analyzed by using meteorological data of precipitation from June to September in Henan Province from 1971 to 2018 and using wavelet analysis,cumulative anomaly and climate trend rate.Based on the climate scenario prediction data of typical paths with different concentrations,the evolution trend of extreme drought in summer in Henan Province under the future climate background was analyzed,and the risk of extreme drought in summer in Henan Province under the future climate warming was revealed.Using future climate scenario data-driven crop growth simulation model,the possible impact of extreme drought on summer maize yield in Henan Province under different climate scenarios in the future was evaluated.The results of this study can provide a scientific basis for disaster prevention and mitigation of summer maize production and response to future climate change.The main conclusions are as follows:(1)In the past 48 years,the overall CDD of Henan Province has shown an increasing trend,reaching the highest value of 27.6 d in 1997 and the lowest value of11.5 d in 1984.From the perspective of interdecadal changes,except for the decline in CDD from 1990 s to 2000 s,the overall trend in the past 48 years has gradually increased.In terms of spatial distribution,CDD in all regions of the province has shown a gradual increase trend,with the largest growth rate in western Henan0.076d/10 a,the minimum growth rate in eastern Henan is 0.013d/10a;the summer CDD in Henan Province had a sudden change around 1996,and there was an obvious small-scale evolution cycle of 5-7a.(2)From the perspective of the whole province,in the next 40 years,the average summer CDD in Henan Province will fluctuate,and the overall trend is slowly rising.The average CDD increased at a rate of 0.2 d/10 a under RCP4.5 and0.7 d/10 a under RCP8.5.The maximum value of average CDD appeared around2051.In terms of interdecadal variation,it also showed a slow upward trend until the peak in the 2050 s.In terms of spatial distribution,under both RCP4.5 and RCP8.5scenarios,the spatial distribution features were high in the east and low in the west,high in the north and low in the south.(3)According to the simulationresults of the model,the yield of maize rainfed in Henan Province under future climate scenarios increases in the order of extreme drought year,normal year and wet year;compared with the average yield under the baseline climate conditions,the yield of maize in all year types decreases.23.2% and38.2% decrease in the average yield of extreme drought year under RCP4.5 and RCP8.5 scenarios,respectively.The average yield of extreme drought in the province under RCP4.5 and RCP8.5 scenarios decreased by-5.2% and-19.1%,respectively,compared with the normal annual yield under the same climate scenario.From the perspective of different regions,the reduction is higher in North and Southwest Henan than in West and East Henan. |
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