- There is an increasing need for development of laboratory
identification procedures for purposes of plant variety protection, seed certification, quality control and consumer protection. In the past there were fewer commercial varieties and field
testing methods based on morphological differences were used satisfactorily. These tests require several months to complete and are
subsequently of limited practical use. With the large number of
current varieties, visual differences are much smaller and the
task of identification is increasingly difficult.
This study was initiated to investigate various morphological, chemical and biochemical characteristics of 25 varieties
grown in the Pacific Northwest.
The five tests described in this study provide the basis for
a laboratory identification system for these varieties. The coleoptile
color test was of limited value for these varieties, since only
Golden exhibited a purple coleoptile while the remaining varieties
were green. The seedling pubescence test separated the varieties into
two groups: slightly pubescent and pubescent. However, the
variation of the pubescence density caused by environmental conditions limits its practical use.
The phenol test separated the varieties into three distinct
groups: Light Brown, Brown, and Mixed. Four varieties, Barbee,
Daws, Druchamp, and Luke, exhibited a mixed phenol reaction. This
mixture was characteristic of these varieties since they were uniform for the other characters.
Esterase, catalase, acid phosphatase and glutamic oxaloacetic
transaminase were not useful for separating the varieties since
all of them developed similar banding patterns for each enzyme.
Peroxidase electrophoresis separated the varieties into two distinct groups on the basis of the presence or absence of a single
Gliadin electrophoresis was the most discriminating test,
distinguishing all the varieties except for those genetically
closely related. These included varieties within three variety
groups: Gaines and Nugaines; Fielder and Fieldwin; and Hyslop,
Hill, McDermid, and Stephens. The phenol test provided a useful
separation of the group of four varieties which were uniform for
gliadins. Hill and Hyslop developed a brown phenol stain while
McDermid and Stephens exhibited a light brown stain. Further
identification might be possible by other means, such as pathogen resistance, isoelectric focusing and other chemical tests.
In practice, unknown samples should be compared to authentic,
standard samples for final identification.