Research For The Infection Factors Of Bipolaris Oryzae And The Resistance To Rice Brown Spot

Rice brown spot is a global fungal disease caused by the leaf brown spot fungus. Recentyears the disease occurs gradually in many parts of our country, and it was caused great economiclosses to farmers. There are rarely reported for leaf brown spot fungus System. In order to provide atheoretical basis for the prevention and treatment of the disease, this paper made a study on thisdisease infection conditions, and carried out the investigation of the host range of the pathogens.Main contents and results are as follows:1．Research on infection conditions of the rice leaf brown spot fungusInfection experiments was made in the rice-growing season, analog brown spot fieldnatural incidence. The results showed that: The rice brown leaf spot fungus infection optimumtemperature is33°C (noon), and the optimum moisturizing time is24h, infection after vaccination,after lasting more than12h of25-30°C is conducive to the invasion of pathogens.2. Study on the host rangesThe pathogenicity was measured in the18plant species, including10species after theonset of infection, eight kinds of plant no disease. Its host range was more widely. Especially grass,sorghum,wheat incidence was more serious, the condition index reached64,56,27.3. Identifying and screening of resistant varieties of rice brown spot field119tested varieties of resistance rice brown spot were identified in Jiangsu ProvincialAcademy of Agricultural Experiment Land. High resistance (HR) rice varieties was6, accounting for5%of the identification species. Moderately resistant (MR) rice varieties was14, accounting for11% of the identification species. Sense of (S) rice varieties was74, accounting for62%of theidentification species. High sensitivity (HS) rice varieties was25, accounting for21%of theidentification species.4. The relationship of silicon and the resistance to rice brown spotThe resistance to rice brown spot was identified for19varieties of mutant bank in Danyangrice experimental field of Nanjing Agricultural University. The resistance to brown spot was differentin different rice varieties. The maximal disease index is71, and the minimum is3. The silicon contentof the new leaves is generally higher than the old leaves in the same species. There are a highlysignificant negative correlation between the silicon content and the disease index. Indicating that thehigher the silicon content, anti-The disease is more strong.