Experiments were done to determine pathogenic variability
and pathogenic adaptation of Septoria tritici to different
wheat cultivars. Fifteen S. tritici isolates from
California, Oregon, and Texas were evaluated on seedlings of
two sets of geographically diverse wheat cultivars under
greenhouse conditions. Significant isolate effects, cultivar
effects, and isolate X cultivar interactions were found,
though the interaction terms were very small compared to the
main effects of isolate and cultivar. All except one isolate
were virulent to two sets of cultivars, and the virulence
patterns varied among the isolate-cultivar combinations.
Variability in virulence among the S. tritici isolates
within and between locations also was observed. The isolates
were usually more virulent to the cultivars of the same
geographic origin than cultivars of other locations, and
this demonstrates location-specific adaptation of S.
tritici.
Four populations of S. tritici, secured from four
winter wheat cultivars grown in a field experiment, were
evaluated on seedlings of the same wheat cultivars under
greenhouse conditions. Significant spore population
differences, cultivar differences, and spore population X
cultivar interactions were obtained. The interaction term
was fairly large compared to the main effect of spore
population, and it is likely that the significant
interaction was due to increased virulence of S. tritici to
its own cultivar of origin. The "own" spore population
(inoculation with spore population obtained from the same
cultivar) produced significantly larger area under disease
progress curve on the cultivar of origin than the "others"
(inoculation with spore populations obtained from other
cultivars), suggesting cultivar-specific adaptation of S.
tritici. Spore populations obtained from the two susceptible
cultivars indicated general adaptation to all of the test
cultivars, whereas, the spore population secured from the
most resistant cultivar showed specific adaptation to its
cultivar of origin. Consequences of pathogenic variability,
increased virulence, and adaptation of S. tritici to wheat
cultivars are discussed. / Graduation date: 1994
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/35367 |
| Date | 01 November 1993 |
| Creators | Ahmed, Hafiz Uddin |
| Contributors | Coakley, Stella M., Mundt, Christopher C. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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