Identification Of Key Meteorological Factors And Risk Assessment Of Wheat Scab In Jiangsu,China

Wheat scab is one of the important agricultural diseases and insect pests in China,and is a typical meteorological disease.It will not only cause a serious decline in wheat production,but also produce toxins that reduce the quality of wheat,which is listed as a crop diseases by the Ministry of Agriculture and Rural Affairs.Jiangsu is one of the important wheat producing areas in the eastern China.However,the climate conditions in the north and south of Jiangsu are greatly different due to its location in the transitional zone between the warm temperate zone and the subtropical zone.With the further intensification of global warming,there are some problems such as unclear leading meteorological factors affecting the occurrence of wheat scab,and unclear potential risk and risk zoning.Under this background,it is of great significance to clarify the occurrence of wheat scab,and carry out the relevant risk assessment and zoning to guide the precise control and efficient emergency management of wheat scab in Jiangsu.In view of this,this study uses the theories and methods of meteorology,plant protection,ecology and other disciplines,based on multi-source data such as meteorology,plant protection,remote sensing,statistical yearbook,etc.,to clarify the key meteorological factors for the occurrence of wheat scab in Jiangsu,and carry out a comprehensive assessment of the occurrence risk of wheat scab.The main results are as follows:(1)Based on remote sensing data and observation data of agrometeorological stations,a remote sensing extraction method of wheat planting based on the phenological difference feature was established.The method has high reliability.The R2 between the remote sensing extraction results of wheat planting area and the statistical yearbook data at the city scale is 0.92,and the root mean square error is 437.4 km2.From 2000 to 2020,the wheat planting area in Jiangsu ranged from 18566.3 to 25680.8 km2,showing the characteristics of ’first decrease,then increase,and then decrease’.Among them,the wheat planting area in northern and central Jiangsu increased significantly,while the wheat area in southern Jiangsu has continued to decrease since 2010.The density of wheat patches in northern and central Jiangsu is the same,however the shape of wheat patches in central Jiangsu is more regular and connectivity than that in northern Jiangsu.The wheat patches in southern Jiangsu are relatively fragmentation.(2)Using the monitoring data of wheat scab in Jiangsu and the meteorological observation data of the same period,it was found that the frequency of wheat scab in Jiangsu showed an increasing trend during the study period.The frequency of wheat scab in southern Jiangsu was the highest,reaching 90.29%.The frequency of wheat scab in central Jiangsu increased the fastest,reaching 2.08%·yr-1(P<0.05).The occurrence level of wheat scab in Jiangsu is mainly level 1.However,the major occurrence years of wheat scab are in 2003 and 2012,and both occurrence level are mostly level 3 or above.Combined with the boosting regression tree method,it was found that the key meteorological factors and their influencing thresholds of wheat scab in Jiangsu varied greatly due to different regions and wheat growth periods.In addition to temperature and humidity,wind speed in northern Jiangsu and sunshine hours in central and southern Jiangsu are also important meteorological factors affecting the occurrence of wheat scab.On this basis,a prediction model of wheat scab occurrence in Jiangsu is constructed according to different regions and wheat growth periods.The model has the ability to be dynamically updated,and it has the relatively high accuracy.It predicts better when the prediction time is close to the heading and flowering period.(3)Based on the ’four factors’ method in agricultural meteorology,the index system and comprehensive evaluation model for the risk of wheat scab occurrence in Jiangsu are constructed according to four aspects:the risk of disaster-causing factors,the sensitivity of disaster-bearing environment,the vulnerability of disaster bearing body as well as the ability of disaster prevention and mitigation.It is found that the comprehensive risk of wheat scab occurrence in Jiangsu is mainly medium risk,and the multi-year average value of the area ratio in the study period is 29.49%.The low-risk areas accounts for the smallest proportion,with a multi-year average of 16.14%.The comprehensive risk of wheat scab is the highest in central Jiangsu,followed by southern Jiangsu and northern Jiangsu.Specifically,northern Jiangsu has a lowest risk of disaster-causing factors and a highest vulnerability of disaster bearing body.The highest risk of disaster-causing factors is in central Jiangsu.In comparison,southern Jiangsu has a highest sensitivity of disaster-bearing environment and a lowest risk of disaster prevention and mitigation.On this basis,the key areas for wheat scab prevention are further determined in Jiangsu.