A negative relation between grain protein content and
grain yield is frequently observed in wheat (Triticum
aestivum L. em Thell) i.e. as grain yield increases, grain
protein decreases. It has been suggested that the inverse
relation between grain yield and protein is in part the
result of developing high yielding semi-dwarf wheat
cultivars with an increased harvest index. This
investigation was undertaken to determine the nature of the
possible association of grain yield and protein content as
influenced by harvest index, biological yield, plant height
and kernel weight in winter wheat populations grown in
Oregon.
Progenies derived from three crosses of winter wheat
were solid-planted in two environments during two seasons.
Phenotypic correlations showed a moderate negative
association of grain protein content with both grain yield
and harvest index. The magnitude of the genetic
correlations suggested the presence of genetic relationships
among these traits. Selection for harvest index among these
crosses could cause a correlated reduction of grain protein
content.
To investigate if the relationships between grain
protein content and selected plant growth traits were
similar when grown under space-planted and solid seeded
stands, progenies of two winter wheat crosses were evaluated
during two seasons. Performance for grain yield and grain
protein content was different under contrasting sowing
densities as values were not correlated between sowing
densities. This indicates the need to evaluate these traits
in solid-seeded stands. Harvest index, as well as plant
height and heading date, could be effectively selected under
space-planted or solid seeded conditions. Associations
among traits were reliably estimated in space-planted
stands.
To evaluate the effect on grain protein content when
grain yield and harvest index are modified, the plant growth
regulator Paclobutrazol was applied to selected winter wheat
genotypes under field and greenhouse conditions.
Paclobutrazol increased grain yield and harvest index values
of all genotypes in the greenhouse, while only some
genotypes improved these traits under field conditions.
Grain protein content, however, remained unchanged. Higher
grain yields were obtained in both greenhouse and field
experiments. / Graduation date: 1991
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37155 |
| Date | 29 November 1990 |
| Creators | Costa, Jose Maria |
| Contributors | Kronstad, Warren |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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