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Description for Barley Cultivars in North America
Head and kernel characters of barley
From American Malting Barley Association
Barley Variety Dictionary
Head— Parts of the barley head are identified in Figure
1. Barley heads may have either six rows or two rows of kernels. In 6-row barley
there are three kernels at each joint (node) on alternate sides of the head,
resulting in six rows of kernels. In 2-row barley only one kernel develops
at each joint on alternate sides of the head, resulting in two rows of kernels,
Figure 2.
The number of rows of kernels is a stable character and is very useful
for identifying barley varieties. The difference in the appearance of threshed
samples of 6-row and 2-row barley varieties is distinct and useful in variety
identification. In threshed samples of 6-row varieties, two-thirds of the
kernels are twisted in appearance. These are the lateral or side kernels
which twist as they grow alongside and overlap the central kernels. In
threshed samples of 2-row varieties, all of the kernels are straight and
symmetrical because there are no lateral kernels. These differences can
be observed in the individual variety descriptions. In order to identify
6-row and 2-row barley in mixed samples, it is necessary to distinguish
between central kernels of 6-row varieties, which are straight and symmetrical,
and kernels of 2-row varieties. Kernels of 2-row varieties are generally
broader and do not taper as sharply towards the attachment end of the kernel
as is the case in central kernels of 6-row varieties, Figure 3.
The density of a head of barley depends on the length of the rachis
internodes. If these internodes are short, the kernels are crowded close
together and the head is dense. If the internodes are long, the head is
lax as the kernels are spaced farther apart. Among varieties there are
all gradations between dense and lax. This character is influenced to a
moderate extent by environment and is therefore of limited value for identification
purposes.
In 6-row barley the rows of lateral kernels may overlap each other in
varying degrees. The extent of overlapping ranges from none to almost the
entire length of the head, Figure 4. Overlapping of the lateral kernels
is expressed first at the tip of the head and progresses towards the base
of the head as the amount of overlapping increases. In most cases overlapping
is found only in the upper third of the head. In varieties having no overlapping
or high degree of overlapping, this character is useful in identification.
Position of head on the maturing barley plant can be described in three
main groups: erect, inclined, nodding. There is considerable variation
in this character within varieties but it is nevertheless a useful descriptive
character.
The stem of the barley head (rachis) is flattened. The edges of this
flattened stem have varying degrees of hairiness. Most varieties have numerous
hairs, some varieties are intermediate and only a few have non-hairy edges,
Figure 5.
This is a useful identification character in varieties differing from
the majority and can generally be used in threshed samples because part
of the rachis remains attached to some kernels.
Awns — Heads of barley may be awned, awnless
or hooded. awns may be long or short with various combinations of awn length
on the same head, Figure 6. Awnless and hooded types are shown in Figure
7.
Awns can be classified into three groups based on the degree of barbing;
rough, semismooth and smooth, Figure 8. Environment has some effect on
the development of barbs on the awns, resulting at times in some overlapping
in the smooth and semi-smooth awn groups. Occasionally in the semi-smooth
group, awns may be almost fully barbed. However, this character is generally
stable and is useful in variety identification.
Glumes — Location and appearance of glumes
are shown in Figure 1.
Hairiness of Glumes — Variations in the length and location of
hairs on the glumes can be seen in Figure 9.
In some varieties this character is constant while in other varieties
it is variable.
Length of Glume Awn— Glume awns are measured in relation to the
length of the glume. In most barleys the glume awn is either equal to the
length of the glume or twice the length of the glume, Figure 1.
Hull — Barley varieties have either covered
or naked kernels, generally referred to as hulled or hull-less, Figure
10.
This character is stable and therefore very useful. In hulled varieties
there are differences in the tightness of adherence of the hull. The degree
of adherence of the hull is subject to variation due to environment but
is a useful character in some varieties.
Wrinkling of the hull can be described in three classes as shown in
Figure 11.
The degree of wrinkling is highly dependent on environment and is more
fully expressed in mature barley than in immature barley. Certain varieties
have distinctly characteristic wrinkling and this character is useful in
these cases.
Aleurone — There are two major classes
of aleurone color: colorless and colored or blue. There are several degrees
of blue color, the expression of which is highly influenced by climatic
conditions. Color in blue aleurone varieties is expressed more fully under
arid and semi-arid conditions than under humid conditions. In some cases
under humid conditions, this color may not develop enough to be readily
seen, particularly in varieties that have inherently light blue aleurone
color. Examination for aleurone color in hulled varieties can best be made
by using a barley pearling machine to remove the hull.
Rachilla — Length of the hairs on the
rachilla is one of the most stable characters for identifying barley varieties,
Figure 13. The abundance of hairs in varieties with long rachilla hairs
is useful in a few cases. The length of the rachilla itself is of minor
taxonomic value. Abortive rachillas, Figure 13, may vary from none to as
high as 50% in some varieties. This is a useful identifying character only
for those varieties which normally contain a high per cent of abortive
rachillas. Expression of this character is dependent to some extent on
environment.
Veins — Prominence, continuity and shape
of the central and lateral veins (Figure 12) are of some value in variety
identification. Varieties differ in the number of barbs on the lateral
veins, Figure 14. The development of barbs is affected by environment.
Some varieties are not pure for this character and may show a wide range in number of barbs.
Crease — Shape of the crease is influenced
by environment and the extent of development of the kernel. While the expression
of this character is variable, it is useful for variety identification
in a specific area. Many varieties have creases of similar shape. Distinct
differences for this character can be found in certain varieties making
it useful for identification purposes. The shape of the crease may vary
from wide, open and V-shaped for the full length of the kernel to tightly
closed for almost the entire length of the kernel, with many variations
between these two conditions, Figure 15.
Point of attachment— The width of the
point of attachment and shape and length of the narrowed part of the base
of the kernel are also useful. Some varieties have a short stem-like projection
from the point of attachment on some of the lateral kernels.Figure 16.
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