| Oats(Avena sativa)is an important annual grain and forage crop in China,which plays an important role in animal husbandry production and agricultural structural adjustment in China.The planting area of oats has been increasing year by year,and the impact of diseases on its yield and quality has also increased,which has become one of the main restrictive factors for the development of the oat industry.This study mainly focused on the main areas of Longzhong and Hexi oats in Gansu Province as the main survey areas.From 2017 to 2018,a systematic study of oat diseases in different growth periods was carried out,including field investigation,pathogen isolation,morphological and molecular biological identification,and pathogenicity test.In addition,the inhibitory effect of endophytic fungus strains was also explored.The main results are as follows:1.Through the investigation of common diseases in oat seedling stage and filling stage,it was found that the diseases occurred in the seedling stage were lighter than those in the filling stage.Drechslera leaf spot was the main leaf disease of oats at the seedling stage and the filling stage.The incidence rate at the seedling stage was 0.95%-9.61%.The incidence rate at the filling stage was 9.1%-99.4% and the disease index was 6.8-74.07.Oat red leaf(Barley Yellow Dwarf Virus,BYDV)generally occured during the filling period,with an incidence rate of 2.0%-36% and a disease index of 2.19-28.8.Among them,the incidence rate of Dingyan 2 in Tongwei was the highest,reaching 36%,and the disease index was 28.8.Crown rust(Puccinia coronata)and smut(Ustilago avenae)only occurred on a large area on Dingyin 1 in Tongwei,with the incidence rates were 100% and 15.5%,respectively,and the disease index of crown rust reached 91.27.Diseases at the roots and stem bases of seedlings had occurred everywhere,with an incidence rate of 0.02%-2.93%,and the most serious incidence in the Shandan.The incidence on Qingyin 1 reached 2.93%.The frost damage at the seedling stage mainly occurred in Tianzhu and Tongwei,with an incidence rate of 3.11%-6.42%.2.A total of 364 fungal strains belonging to 14 genera were isolated by separating the infected plants at the oat seedling stage and the filling stage.According to the isolation rate,morphological characteristics,polygenic phylogeny and pathogenicity of various strains,four main pathogens of root diseases were identified: Fusarium avenaceum,F.proliferatum,Rhizoctonia solani and Microdochium nivale;four main pathogens of leaf diseases: Drechslera avenae,Pyrenophora avenicola,Epicoccus layuense,Alternaria alternata.From these pathogens,oat leaf spot caused by E.layuense was the first report in the world which belonged to the new record of international diseases.The root rot caused by F.proliferatum and M.nivale and the leaf spot disease caused by A.alternata and P.avenicola were the first reports in China which were new records of disease in China.3.The pathogenicity evaluation of 9 strains of F.avenaceum selected from 3 areas was carried out through three indexes: the relative reduction rate of plant height,the relative reduction rate of root length and the disease index.The results showed that the isolated strains in each region had strong pathogenicity,the relative reduction rate of plant height was 42.2%-74.9%,the relative reduction rate of root length was 43.9%-74.8%,and the disease index ranged from 54.3-94.3.There were differences in the pathogenicity of F.avenaceum in different regions.The pathogenicity of F.avenaceum selected in Tianzhu was significantly lower than that in Tongwei and Shandan and there was no significant difference in pathogenicity of F.avenaceum between Tongwei and Shandan and between different strains in the same area.4.The growth-promoting Fusarium strain Y-Y-1 and 7 common pathogens on oats were subjected to dual culture and fermentation broth inhibitory test.The results showed that the strain Y-Y-1 had a significant inhibitory effect on D.avenae and Py.avenicola. |
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