Preparation Conditions Of Inoculation System And Analysis Of Disease Resistance Of Cercospora Zeae-Maydis

Corn,as an important economic crop,plays an important role in agricultural production and national economic development in China.The gray leaf spot disease of corn has progressively becoming serious and turned to the main disease from the secondary,because of the change of climate conditions and no-tillage planting system,which has threatened the corn yield.Based on the identification of pathogenic bacteria of maize gray spot in Liaoning Province in 2017,the virulent strains were selected and the preparation conditions of solid medium were optimized.The inheritance of disease resistance of different early maturing inbred lines and the disease resistance of some main cultivars in Liaoning Province were analyzed.The main results are as followed:1.Through isolated identification of 52 disease samples from different areas of Liaoning Province,60 strains were purified and identified as Cercospora zeae-madis by morphology and molecular biology.Twenty dominant strains were inoculated with 7 inbred lines with different levels of resistance and susceptibility,and pathogenicity was determined.Pathogenicity is assessed by the initial stage of onset,the rate and size of lesion spread.In addition,19 strains of highly pathogenic strain(DD-02)were selected for solid medium preparation and genetic analysis of resistance.2.To explore the effects of different temperature,culture time and light conditions on sporulation yield of solid grain culture medium,The results of screening 26 solid media showed that 18 was the best medium which contains 100 g Corn kernels,0.5 g yeast extract powder,0.3 g calcium carbonate and 3 g Corn Leaf powder.The sporulation yield was the highest in 12 days,and the optimum temperature was 20 ?.It is not suitable to produce spores at too high or too low temperature,and it is better to cultivate spores under all dark conditions than others.3.The inheritance of Grey Spot Resistance in 20 inbred lines and their hybrids was systematically analyzed by artificial inoculation.Five inbred lines were selected as male parent and 19 inbred lines as female parent.The results of disease resistance identification showed that the resistance of parents to gray leaf spot was quite different,but the resistance performance after hybridization was better than that of their parents.The resistance of the first generation of hybridization was between parents,and the resistance performance tended to be maternal.4.To make a resistance analysis by artificial inoculation,the result showed that among 104 cultivars,1.00% are highly resistant,30.76% are resistant,52.87% are moderately resistant,and 15.37% are susceptible.The incidence of gray spot disease in the field was lighter than that in the seedling stage,probably due to persistent high temperature.Data analysis showed that the main cultivars had some resistance to gray spot disease,half of which were moderate resistance and few were high resistance.