Study On Pathogens And Control Of Wheat Black Point

The black point disease of wheat occurred in most grain-growing areas of the world, causing considerable financial losses, and there were different pathogens isolated from wheat seeds in different years and areas. Domestic and overseas scholars published plenty of roports in the symptom, pathogenic types and etc about black point disease of the wheat, but there were a few reports in pathoginc biology charaters, the mutual of host and pathogen. So the thesis researched pathogenic biology characters, invading process .The researchful results would be described in this thesis focused on the below several aspects.(1) According to the Koch's postulates, Bipolaris sorokiniana and Alternaria alternata were the main pathogens in all grain-growing areas .The isolated frequency were 6.67% and 76.67% respectively.(2) By dipping Bipolaris sorokiniana and Alternaria alternata in greenhouse experiment, the result showed both pathogens could cause black point disease of the wheat .The re-inoculating isolated frequency were 99.50% and 96.67% respectively.(3) The study of pathogenic biology characters suggested that Monosaccharides, polysaccharides and soluble starch were all utilized as carbon sources, in which soluble starch, glucose, saccharose and maltose were better than the others. Both organic nitrogen and inorganic nitrogen were utilized as nitrogen sources, in which peptone and beef cream was the best. The two fungus could grow between 4～32℃, pH 3～12, with optimal at about 25℃～28℃, pH 6～8. The fungus growth was inhibited under 24h/d light. The conidia could germinate at 5～38℃a nd pH 3～12, with the optimal at 25℃, and about pH 6.But optimal germination and growth conditions were not always modest to conidia produce.(4) The period of infection was from the flowering stage to breeding stage, the modest period of infection was the middle flowering stage and early filling stage.(5) The pathogens could invade wheat seed from the part of rachilla, lemma ,germen and glume.(6) There were different in spore geminating and infesting between the two...