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 หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Evaluation of Maize Varieties for Resistance to Northern Leaf Blight under Field Conditions in Ethiopia) ผู้เขียน: Daniel Abebe,  นายณรงค์ สิงห์บุระอุดม, รองศาสตราจารย์ , ดร.สมศิริ แสงโชติ, รองศาสตราจารย์ , ดร.เอ็จ สโรบล, ศาสตราจารย์ สื่อสิ่งพิมพ์:pdf AbstractA study of reaction of thirteen maize varieties to northern leaf blight mainly caused by Exserhilum turcicum (Pass) Leonard and Suggs, were conducted at three locations Gambella, Abobo and Bako during 2003 and 2004 crop seasons. Variation among maize varieties was observed for several disease variables; the number of lesion, size, incidence, area under disease progress curve (AUDPC) and severity rating scale. In general, significant differences among genotypes were observed for data based on lesion number, size, AUDPC and severity rating scale at all locations. Susceptible varieties Gussau, Aboboko and Local- M had high AUDPC, large lesion size, fast onset of disease and many lesions in numbers. The host entries used in this study indicated that Kuleni was the most resistant to northern leaf blight across three locations, with low rating score. There was different response among varieties depending on disease intensity at each location. At Abobo, the final severity increased from 0.00 to 96.66% in 2003 and the results observed from 10.00 to 96.66% at Bako. However, at Gambella the incidence was as low as from 0.00 to 83.33%. Disease assessment methods were generally correlated with one another. Several varieties showed similaly significant reaction to disease in all locations. This meant that there was no virulent difference existing in the pathogen populations from location to location. |
หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Morphological, Cultural and Pathogenicity Variation of Exserohilum turcicum (Pass) Leonard and Suggs Isolates in Maize (Zea Mays L.)) ผู้เขียน:Daniel Abebe, นายณรงค์ สิงห์บุระอุดม, รองศาสตราจารย์ สื่อสิ่งพิมพ์:pdf AbstractSurveying and collecting isolates of the fungus Exserhilum turcicum (Pass) Leonard and Suggs, the causal agent of Northern Corn Leaf Blight (NCLB), were conducted in two maize growing areas of Ethiopia in 2004 and used for studying cultural, morphological and pathogenicity varations. The results revealed that NCLB was widely distributed in almost all surveyed areas. Seventy isolates were studied for morphology and most of the conidia shapes were curved, spindle and elongated. The size of the conidia averaged 93.97 ?m in length and 13.11 ?m in width. The number of septa was found to range from 2 to 7. The study of cultural characteristics showed that variation existed among representatives of 28 isolates in colony growth, colony color and pigmentation. Conidial growth rate of 28 isolates was significantly different after growing the fungus on PDA. Twenty representative isolates were selected and evaluated for pathognicity on 11 seedlings maize varieties. A significant difference of disease reaction was found among tested isolates, varieties and isolates by varieties interaction. Lesion type varied in size from 0.69-2.91cm.The most virulent isolate, GOR, was found to cause disease on five varieties. Lesion size that was classified as resistance, was 0.69 to1.12cm2. Susceptible lesion size was between 1.17-2.91cm2. By applying the UPGMA in the SAHN program for cluster analysis, a pathogenicity dendogram of 20 isolates were grouped into five clusters of virulent patterns. The results of this study indicated wide variations existed among the fungi studied, therefore, the effective development of maize variety resistant to northern corn leaf blight should involve using virulent isolates, together with a mixed isolates, in order to test the disease interactions and select for resistant genotypes. |
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