Identification Of Disease Resistance And Economic Threshold Of 91 Wheat Varieties To Yellow Dwarf Disease

Wheat yellow dwarf(WYD)is a seriously circulating viral disease in China,causing large-scale wheat yield reduction and economic loss,especially in north and northwest China.WYD is caused by barley yellow dwarf viruses(BYDVs)and is exclusively transmitted by vector aphids.Infected wheat shows a series of symptoms,such as dwarfing and yellowing in field.Among them,the BYDV-GAV lines occurred seriously in northern China.At present,wheat yellow dwarf disease is mainly prevented through chemical control method,which is easy to cause environmental pollution and pesticide residue.Therefore,screening and identifying varieties of wheat to resistant yellow dwarf disease is one of the cost-effective methods,and it is also an important means to prevent wheat yellow dwarf disease.In addition,the economic threshold of WYD is studied in this paper,and the main results are as follows:(1)2 high-resistance varieties were identified in 91 wheat varieties by heap measurement method,namely Xinong 979 and Shaan 229,with a disease index below 10,accounting for 2%;11medium-resistant varieties,accounting for about 12%;YF168,Xinong569 and Shanhe 181 varieties with disease indexes of about 20,showing good resistance;30kinds of susceptible varieties,accounting for about 33%;37 kinds of medium-sensitive varieties,accounting for about 41%;other high-sensitivity varieties,accounting for about12%.The disease-susceptible control Xiaoyan No.6 was high-sensitivity,and the disease-resistant control 4 was high-resistance.These resistant varieties screened can be used as parents.(2)Inoculation of yellow dwarf virus GAV at the seedling stage of wheat to analyze the biological effect of the virus on wheat.The results showed that the morphological indices of plant height,panicle length,flag leaf length and flag leaf width were significantly reduced,the chlorophyll content was significantly reduced,the 1,000-grain weight loss rate was significantly increased,the grain protein content was significantly reduced,and the antioxidant enzyme activities of SOD,POD and CAT were significantly increased.In addition,there are some disease-resistant varieties with high disease index,but the1,000-grain weight loss rate is very low,such as: YF169,zhongzhi 18 and so on.(3)The economic threshold(ET)and the economic injury level(EIL)of wheat yellow dwarf disease in Guanzhong,Shaanxi Were studied.Regression analysis with SPSS software showed that the results of the field test showed that when the yield per mu was 350 kg,the EIL= 7.59%,the ET(incidence)= 8.52%,and the ET(disease index)= 2.06;when the yield was 500 kg per mu,the EIL = 5.31%,the ET(incidence)= 8.47%,and the ET(disease index)= 2.04.These economic thresholds have important guiding significance for the prevention and control of local wheat yellow dwarf disease.In summary,through the identification of field resistance,two excellent yellow dwarf disease resistant varieties were screened out,which provided a reference for planting disease-resistant varieties to prevent wheat yellow dwarf disease.The study of Xiaoyan No.6 economic threshold provides a basis for the timely prevention and control of wheat yellow dwarf disease in Guanzhong region of Shaanxi Province.The above results provide new ideas and new ways for the prevention and control of WYD,which have important reference value for producers and are also of great significance for the prevention and control of arboviral diseases.