بررسی پراکنش و تنوع بیماریهای باکتریایی برگ و ریشه چغندرقند

Sugar beet field and storages were inspected in Khorasan, Hamedan and Esfahan provinces during growing seasons and harvesting time .Samples of sugarbeet plants with wilting, blighting, soft rot crowngall and abnormal plants were collected from fields. The symptoms of bacterial spot are dark brown to black streaks and spot on blads and occasionally on petioles and seedstalks. Root symptoms vary soft rot to dry ort. Pieces of the affected specimen were plated on Nas, EMB, King; B DI agar. Strains were isolated and their phenotypic characterstics were identified and compared. Some strains Grom-negtive, rod shaped and aerobic bacterium were isolated from affect tissues. A fluorescent pigment was produced on medium B king. They were negative in test for hydrolysis of starch esculin and arginine. They utilized glucose, fructose, sucrose,innositol sorbitol and produced acid from them. These strains produced a hypersensitive reaction on tobacco and geranium . Strains were identified as pseudomonas syringae were scattered in regions of Khorasan, Hamedan and Isfahan provinces. A Leaf blight of sugarbeet was observed in some samples.These lesions progress inwards, expand and coalesce, giving the leaves a blighted appearence. A Gram _ negetive, aerobic, non molile, rod-shaped bacterium was consitently isolated from symptomatic leaves. Colonies on sucrose nutrient agar were nonmucoid, yellow ,convex and smooth with entire margins. The strains were oxidase negative, nonfluorescent and hydrolyzed casein, gelatin, esculin, starch and tween 80. They were negative in tests for production of arginine dihydrdase. They utilized fructose ,glucose, cellobiose, trehalose, sucrose, maltose, melibiose, xylose, glycerol and produced acid from them. Pieces of crowngall were plated on Di and PDA agar. The colonies of Agrobacterium sp. were isolated from the Hamedan provinces. The results showed that causal agents of leaf spot, leaf blight, soft rot and crowngall can be attributed to pseudomonas syringae, xanthomonas sp, and pectobacterium carotovorum and Agrobacterium sp respectively.

کلیدواژه ها:

چغندرقند ، بیماری باکتریایی برگ ، بیماری باکتریایی ریشه ، لکه برگی ، سوختگی برگ ، پوسیدگی نرم ، تنوع ، پراکنش