Durum wheat cultivars for North-Eastern Oregon have to be competitive
in terms of their yield potential with soft white winter wheat cultivars and meet
strict quality requirements of the milling industry. Combining the high yield
potential of fall planted durum wheat cultivars which have an acceptable level of
winter hardiness with the good quality characteristics of the spring types through
winter by spring crosses is believed to be an appropriate strategy. However, to be
efficient, quality traits of the breeding lines and the nature of their inheritance
must be evaluated early in the breeding process. The primary objective of this
study was to investigate the nature of genetic variability involving two main quality
traits, namely gluten strength and carotenoid pigment content. These traits are
measured by the SDS sedimentation test and by spectrophotometric analysis of
pigment extracts, respectively. Total genetic variability involving grain yield,
kernel weight and protein content was also studied. Combining ability analysis of
a 4x4 diallel cross using two winter and two spring parents was performed
according to Griffing's (1956) Model 1, method 1.
Both additive and non additive type gene action controlled all traits
studied. Non additive type gene action was particularly important for grain yield
and kernel weight suggesting that selection for these traits should be delayed until
later generations (F5 or F6). Protein and pigment content were controlled
primarily by genes functioning in an additive manner although they are also
influenced by significant non additive type gene action. Reciprocal effects were
significant for pigment content suggesting that some maternal effect might be
involved. The predominance of additive type gene action for sedimentation
volume suggests that this trait can be used to screen early generation material
(F2, F3) for gluten strength.
F2 populations generated from the diallel cross were compared in terms of
their genetic variances, potential transgressive segregation and were used to
investigate the possible associations between the traits measured. Winter by
spring crosses were usually characterized by an enhanced genetic variability for
yield and gluten strength. Transgressive segregation for sedimentation volume
was present in these crosses. Protein content was negatively associated with grain
yield. No relationship between gluten strength and grain yield was observed.
Gluten strength did not appear to be associated with total protein content of the
grain. Sedimentation volume varied greatly, even in populations with low
variability in protein content. Consequently, selection on the basis of
sedimentation volume per se would not be result in selecting inadvertently
agronomically unsuitable types. / Graduation date: 1991
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/38041 |
| Date | 29 November 1990 |
| Creators | Ammar, Karim |
| Contributors | Kronstad, Warren E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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