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Genotype-environment interaction and phenotypic stability of selected winter wheats (Triticum aestivium L. em Thell)Larson, Mark J., 1962- 09 May 1997 (has links)
Extensive research has been devoted to evaluating potential
genotype-environment interactions. However, plant breeders are still in
need of a simple way to describe how genotypes respond to different
locations and years. In an environmentally diverse state like Oregon,
significant genotype-environment interactions do occur The resulting lack
of association between actual and genotypic potential yield performance
makes it difficult to select genotypically superior lines. This study was
prompted to evaluate the extent of such an interaction and compare
various yield stability models.
A significant genotype-environment interaction encompassing lines,
environments, and years was discovered for each individual year analyzed
and for the combined analysis of 1992, 1994 and 1995, and 1989
through 1994. Most lines evaluated during 1992, 1994 and 1995 were
adapted to low yielding environments. However, two genotypes
(OR880172 and OR880525) exhibited broad adaptation. Stephens and
Mac Vicar were less adapted to the relatively high yielding Chambers site
than the other genotypes tested during 1992, 1994 and 1995 due to
Septoria tritici infections. The most stable genotypes during the combined
1992, 1994 and 1995 and 1989-1994 seasons were OR870831, Madsen
and OR8500933H. Gene was the most desirable genotype based on
stability and yield for both the combined 1992, 1994 and 1995 and 1989-1994 seasons. Due to an inability to adapt to higher yielding
environments, the cultivar Rohde was the least stable genotype during the
same combined periods. High and low temperatures and precipitation had
minor yet significant effects on yield responses at all three sites during
various periods identified.
Advanced winter wheat selections and cultivars were grown in
three diverse environments and compared over different time periods. Due
to trial design and the objective of identifying superior genotypes from a
set tested in target environments a combination of two methods, stability
variance and a selection index, emerged as the most appropriate
techniques. These approaches are considered the most appropriate
because they use the mean of the trial as a gauge for measuring stability. / Graduation date: 1997
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Multiple location evaluation of winter wheat (Triticum aestivum L.) lines for genotypic and environmental influences on nitrogen assimilation and remobilizationHolmer, Judith C. 09 January 1992 (has links)
Wheat production in the Pacific Northwest consists
mainly of the soft white wheat market class. Over 80% of
this wheat is exported. In recent years there has been an
increase in soft white wheat production (due in a large part
to improvements in the yielding capabilities of the
genotypes grown in the Pacific Northwest). To expand into
different commodity markets, it would be desirable to
diversify and produce wheat cultivars representing more
market classes and product uses. One opportunity would be
to develop cultivars representing the Hard Red Winter market
class. An effort to breed high yielding, high protein Hard
Red Winter wheats is now underway at Oregon State
University.
This research was conducted to gain a better
understanding of the components (genetic and/or
environmental) that determine yield and grain protein
content of hard red wheat genotypes. There were two general
objectives of the research. One was to study the
differences in nitrogen assimilation and remobilization in a
diverse group of winter wheat genotypes grown in the
different agricultural environments of Oregon. The second
objective was to determine the efficacy of using "hill
plots" (micro-plots) as a planting method to screen for
agronomic and nitrogen assimilation traits in geneticly
distinct genotypes which may be used as parents in breeding
efforts.
Results of this study indicate that genetic differences
for nitrogen assimilation and remobilization do exist, and
improvements in Pacific Northwest hard red wheat genotypes
can be made with appropriate selection techniques. Data
also indicate that the traditional high protein wheat
genotypes (from the U.S. Great Plains) do not show an
advantage from a grain protein concentration standpoint when
produced in the Pacific Northwest. Additionally, the
environment played a critical role in determining expression
of harvest index, grain protein concentration, and nitrogen
harvest index. Genotype by environment interactions were
high, suggesting that zone-specific varieties may need to be
developed in order to attain both high grain yields and high
grain protein yields. / Graduation date: 1992
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