Studies On Classification Of Risk Zones About Dry-Hot Wind And Its Impact On Crops In Henan Province

Dry-hot wind is a kind of meteorological disaster,that is particularly sensitive to the response to global warming,it has become one of the important issues in the study of climate change.Henan province is the main planting area of Winter Wheat in China,the winter wheat planting area accounts for 10% of the whole country,and the total output accounts for about 25% of the whole country.Dry-hot wind is a meteorological disaster that occurred in a high temperature and low humidity and accompanied by high wind speed during Winter Wheat grain filling stage.In this paper,according to the standard of dry-hot wind meteorological industry,Firstly,using the daily meteorological observation data of 121 national basic meteorological stations in Henan province from 5 to 31 in May,analyzed the occurrence regularity and regional distribution characteristics of dry-hot wind in Henan province.Secondly,selected the winter wheat sown area,cultivated land area,wheat yield and irrigation area data of the 18 cities in Henan province,based on the method of AHP to construct of risk assessment model of dry-hot wind the hazard,including exposure of winter wheat,the vulnerability and resilience as major indicators,using GIS technology to comprehensively evaluated the risk of dry-hot wind in Henan province.Finally,using the data of 1995-2010 in Zhengzhou area of wheat measurement and 2011-2012 years dry-hot wind test results of artificial simulation,analyzed the effects of dry-hot wind on winter wheat filling velocity and the physiological function.(1)The distribution of daily number and probability distribution of dry-hot wind in Henan province is "high in the north,middle and east,the west and south are few".The average annals number of light dry-hot wind is 0.35 d/a and the average daily number of severe dry-hot wind is 0.13d/a;dry-hot wind has a great difference between the time and the time,in 1980 s for multiple and frequent,followed by the 1990 s,the proportion of light dry-hot wind is 77.3%,and severe dry-hot wind is 22.7%;the occurrence probability of dry-hot wind is decreasing in recent years.(2)In some places in middle Henan and in most cities of northern Henan is in high incidence areas of light dry-hot wind more than 0.8d/a,lowest in the mountainous areas of western Henan;severe dry and hot area including the Central Plains,the area along the Yellow River in Henan and the individual place,western and southern Henan area belongs to low.The proportion of dry-hot wind high in the north area of Henan Province,Western and southern Henan area low,that is closely related to the geographical environment and climate conditions,the temperature is relatively low in mountain area,and the precipitation is abundant,the relative humidity is high in southern Henan,so it is not conducive to the formation of dry-hot wind disaster.(3)The regularity distribution of dry-hot wind hazard is from the west to the east increasing in Henan Province,the risk index of dry-hot wind in Anyang,Hebi,Xuchang and Kaifeng area is high,west and southwest belongs to low.The high exposure of Winter Wheat is mainly distributed in the eastern region of Zhoukou,Shangqiu,Zhumadian,Nanyang,Xinxiang,Anyang and Puyang,the area and the loss of the area are relatively large when they are subjected to the harm of dry-hot wind.The distribution characteristics of vulnerability of dry-hot wind is” Southern high Northern low”,Sanmenxia and Zhumadian area of dry-hot wind vulnerability index is high,easily affected by disasters,northern Henan area is a low value area.The agricultural disaster prevention and mitigation capacity of Yubei area is strong,which is related to the traditional farming and good management in the north area of Henan Province.The results of integrated risk zoning of dry-hot wind in Henan Province showed that the comprehensive risk of dry-hot wind in Anyang,Hebi,Luohe,Zhumadian and Kaifeng of a high degree,in most area of western Henan dry-hot wind in a low risk level.Overall,the eastern part is higher than the west,the north is higher than the south.And putting forward 4 point scientific preventive measures,in order to reduce its impact on the production of wheat.(4)Through the analysis of the grain filling rate of Winter Wheat in Zhengzhou area,the results showed that,the grain filling speed was slow in prophase,fast in metaphase,slow in telophase,the grain filling rate showed a single peak type distribution,in the wheat after flowering 20 ~ 25 d there is a small peak of grain filling occurs,then the grain filling rate decreased rapidly,1000 grain weight reached the maximum after anthesis 35 d in wheat.Through the artificial simulation of the physiological functions of wheat chlorophyll content,photosynthetic rate,root activity,The results showed that the dry-hot wind at middle stage of grain filling had more negative effects than at early stage of grain filling,and the heavy-grade dry-hot wind harmed more than the light-grade one.There was no significant effect on net photosynthetic rate,root injury rate,and grain filling rate of dry-hot wind disaster in the early stage of grain filling,the effect of severe dry-hot wind treatment on the physiological function of wheat in the middle stage of grain filling was greatest,the photosynthetic rate was reduced by 5%,and the root injury reduced by about 8%,so that the final yield of wheat decreased by about 6%.The light dry-hot wind treatment effect is not obvious,severe dry-hot wind will accelerate the decline of wheat yield significantly,appear backflow.