Maize Cultivars Resistances To Maize Rough Dwarf Disease And The Assessment Of Yield Loss Caused By The Disease In Anhui Province

Maize, one of the most widely distributed grain crops in the world, is not only an important food crop, but also the important industrial raw materials and animal feeds. However, due to the influence of various unfavorable factors in recent years, Maize rough dwarf disease has continued to expand, and the harmful extent of the disease has been increasing year by year, which caused severe damage to maize production.Althrough there were a large number of researches of the disease both at home and abroad, the application of the research methods subjected to certain restrictions as a result of the differences of geographic conditions and environmental factors. The systematic study of maize rough dwarf disease in Anhui province can lay the foundation not only for forming the integrated pest management techniques that is suitable for Anhui province, but also for providing the necessary basis for resistance breeding of maize and the rational distribution of disease-resistant cultivars.The severity grading criterion was derived according to the ear length rate；27cultivars， r esistances to maize rough dwarf disease were identified in Anhui Province during2009and2010by the means of the natural disease nursery method. The main results were as follows:1. The ear lengths and the yields of each healthy and infected plant of5cultivars (Liyu16, Jundan18, Zhengdan958, Zhongke11, and Ludan661) were measured during the year of2009and2010. The severity grading criterion was derived according to the ear length rate, that is, when the ratio range of the ear length is0.92-1.00,0.67-0.91,0.41-0.66,0.1-0.40and0, its corresponding disease grading criterion is0,1,3,5and7, respectively. The severity grading criterion has been proved to be simple, reliable and practicable.2. The severity grading criterion was closely correlated to the yield loss, when the disease grading criterion is from0to7, its corresponding yield loss rate is0,25%,62%,86%and100%, respectively. By analyzing the data of disease indexes and yield loss rates of27cultivars with DPS, the regression equations were established respectively. According to the comparison with each other, the Weibull Model has been proved to have the highest fitting degree (Y=0.926818*(1-EXP (-((X+0.524663)/0.749684)^1.6350))). The equation was validated with the related data, and the result supported the feasibility of the equation to predict the yield loss caused by maize rough dwarf disease.3. On the basis of the above,27cultivars resistances to maize rough dwarf disease were identified in Anhui Province during2009and2010. The results showed that there were10cultivars which were above moderately resistant among the cultivars in two years, which accounted for37.04%of the cultivars. The cultivars are Nongda108, Denghai3, Liyu35, Ludan6018, Zhongnongda311, Qidan1, Wanyu17, Jinsai6850, Liyu16and Zhongke4, respectively, and the disease indexes ranges were from21.41%to52.50%. There were13highly susceptible cultivars, accounting for48.15%of the cultivars, and the disease indexes ranges were from65.13%to82.43%. The results showed that the disease resistance performance of each cultivar was basically the same in the different years.