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| dc.contributor.author | Mesfin, Selam | |
| dc.date.accessioned | 2018-10-01T05:21:10Z | |
| dc.date.available | 2018-10-01T05:21:10Z | |
| dc.date.issued | 2018-10-01 | |
| dc.identifier.uri | http://hdl.handle.net/123456789/9010 | |
| dc.description.abstract | ABSTRACT Wheat is one of the most important cereal crops of Ethiopia.Stem rust (black rust) caused by Puccinia graminis f.sp.tritici is one of the most important air borne diseases of wheat (Triticum aestivum) in the high lands of Ethiopia, including North and South Gondar administrative zones. The pathogen is capable to produce new physiological races that attack resistant varieties and develop epidemic under favorable environmental conditions which results in a serious yield loss. However, information on the status of stem rust distribution and races in North and South Gondar zones is limited. Wheat stem rust damage samples were collected in 2016 and 2017 in the North and South Gondar administrative zones of Wegera, Debark, and Farta and Lay Gayint districts. Thus, this study was carried out to investigate the distribution and intensity of wheat stem rust and to detect the virulence spectrum of P. graminis f.sp. tritici. The survey result showed that out of the 95 wheat fields assessed in the two zones, 70.91% were infected by the stem rust disease. The overall mean incidence and severity of wheat stem rust in both zones was 4.76% and 3.31% respectively during 2016 main cropping season and out of the 55 wheat fields assessed in the two administrative zones, 91.5% were infected by the stem rust disease. The overall mean incidence and severity of wheat stem rust in both administrative zones was 49.59% and 23.41% in both zones during 2017 main cropping season respectively. The physiologic races of the rust fungus were determined on seedlings of the standard wheat stem rust differentials following the international system of nomenclature. One hundred fifty samples were analyzed in 2016 and 2017 cropping seasons which were collected from Wegera, Debark, Farta and Lay Gayint districts of North and South Gondar administrative zones. From 95 samples analyzed in 2016 three races which included TKTTF, TTTTF and RRTTF were identified. Similarly three races namely, TKTTF, TTTTF and TTRTF were identified from 55 stem rust samples analyzed in 2017. Race TKTTF (Digelu race) was predominant and widely distributed in all the zones with xv 72.7% and 38.1% in 2016 and 2017, respectively. It was virulent on all the Sr genes except Sr11, Sr24 and Sr31. The widest virulence spectrum was noted on race TTTTF making 90% of the Sr genes non-effective. This race also had wide spatial distribution next to TKTTF with frequencies of 18.9% and 57.1% in 2016 and 2017 cropping seasons, respectively. Races RRTTF and TTRTF were detected only at single locations in the two seasons. Most genes possessed by the differentials were ineffective against one or more of the tested isolates. Only the differential host carrying Sr24 and Sr31 were effective to all the races identified in the districts. Stem rust resistance gene Sr24 and Sr31 was found to confer resistance to all of the races isolated in this study.These genes could be used in combination with other genes through gene pyramiding in breeding for resistance to stem rust in the study area. Key words: Differentials, Puccinia graminis f.sp.tritici, Race, Stem rust | en_US |
| dc.language.iso | en_US | en_US |
| dc.title | SURVEY AND VIRULENCE DISTRIBUTION OF WHEAT STEM RUST (Puccinia graminis f.sp. tritici) ON WHEAT IN NORTH WESTERN ETHIOPIA. | en_US |
| dc.type | Thesis | en_US |
