Field response of bread wheat genotypes to Septoria tritici blotch
2000
Temesgen Kebede (Kulumsa Research Center, Asella (Ethiopia)) | Payne, T.S. (Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), Addis Ababa (Ethiopia))
A field experiment was conducted in order to evaluate bread wheat genotypes for resistance to Septoria tritici blotch. Thirty-six bread wheat genotypes were evaluated at the Bekoji and Holetta Agricultural Research Centers. The combined analysis of variance showed that the mean squares due to genotypes, environments and the interaction effect were significant (P0.01) for percentage necrotic leaf area. Mean separation of the percentage necrotic leaf area showed that advanced lines HAR 3640, HAR 3638, HAR 1698, HAR 2096, HAR 3641 and a commercial cultivar Mitike were resistant to Septoria tritici blotch as compared to a susceptible check. A significant negative correlation was found between the disease severity and days to heading and plant height. A resistance parameter, deviation from the regression of infection on days to heading and height, was defined by eliminating the linear effects of escape mechanisms by late heading or tall stature. Using this resistance parameter,. the advanced lines mentioned above were found to have true genetic resistance with the exception of HAR 3640. The resistance observed under field conditions for HAR 3640 was due to escape mechanism(s). This study recommends that when screening germplasm for resistance to Septoria tritici blotch, the severity data must be corrected for the effects of days to heading and plant height, especially when the genotypes are not grouped into maturity classes.
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