Pathogen Identification, Resistant Materials And Fungicides Screening Of Rice Brown Panicle Disease In Heilongjiang Province

Rice is one of the important food crops in the world, China has the largest producer and consumer about rice in the world. Heilongjiang province is the main rice production areas in China. In recent years, with the increase of rice planting area in Heilongjiang province, planting single variety of rice and the influence of environmental conditions, Brown Panicle Dise ase has become one of the main rice diseases, which affecting the yield and quality of rice. To control this disease and reduce its harm in rice production, it is imminent to study the identification of pathogen, screening of resistance resource, chemical control and molecular detection of the pathogen in Brown Panicle Disease in rice.The pathogen was separated and identified from the typical diseased panicles about 14 cities and counties in Heilongjiang province. The pathogen of Brown Panicle Disease in rice was identified by using morphological and molecular biological techniques. The biological characteristics of Alternaria alternata were researched in this study. The toxicity test of 15 fungicides to A. alternata and the selection of resistant varieties were completed, molecular detection system of A. altenata was established in this study. The main results are the following:(1) It had been identified that the pathogen of Brown Panicle Disease in rice was Alternaria alternata(Fr.)Keissl.(2) The optimum medium of A. alternata was Rice Potato Agar, the optimal cultivation temperature was 27℃, the optimum p H was 6.5, the optimum light condition was dark. the optimum Carbon source was Fructose and sucrose, the optimum Nitrogen source were tryptone and beef extract. The optimal cultivation temperature conidia germination of A. alternata was 30℃, the optimum p H was 7 and the optimum light condition was dark.(3) A pair of species-specific primers was designed to detect A. alternata based on ITS sequence analysis. PCR amplification of all the isolates strains was performed by using the specific primers. A single amplification product of 170 bp was detected from DNA of A. alternata isolates. No 170 bp amplification product was detected in any of the other tested isolates. It is proved that this pair of primers designed by this research has the specificity of A.alternata. The detection minimal amount of the PCR method was of 1.0 ng/μL from template DNA of A. alternata. The primers could also detect the pathogen in infected rice panicle after 48 h inculated with A. alternata.(4) In this experiment, the optimum inoculum density was 106 conidia/m L. Two resistant varieties were screened, they were Longjing 43 and Longjing 21; Eight middle resistant varieties were screened, they were Mudanjiang 28, Longjing 42, Suijing 8, Beidao 3, Jinhe 1, Suijing 4, Kendao 6 and Beidao 5.(5) Five fungicides which have the inhibitory effect on A. alternata were selected. Pyraclostrobin, oxime – tebuconazole and prochloraz had the obviously inhibitory effect on the mycelial growth of A. alternata, their EC50 were 0.0475 μg/mL, 0.1453 μg/m L, 0.8841 μg/m L, respectively. Pyraclostrobin, ethylicin and Polyoxin had the higher inhibitory effect on the spore germination of A. alternata effectively, their EC5 0 were 0.0002 μg/mL, 0.0005 μg/m L, 0.0412 μg/m L, respectively. Pyraclostrobin had inhibitory effect on the mycelial growth and spore germination of A. alternata.