Barley for Food and Health: Science, Technology, and Products

IMPROVING THE BARLEY CROP 33
or even essential in the end product, the barley kernel. Hence, barley breeders
began to include emphasis of such characteristics in selection programs as they
were identified. This has become especially important for malting quality traits,
such as enzymatic levels and various aspects of the kernel composition, as the
utility of barley for beverage production has become more valuable than the utility
of barley for feed. Modern barley cultivars used for malting and brewing are
selected as much for their malting characteristics as they are for their productivity
characteristics. The two criteria are often at odds with one another, requiring
close attention of the breeder.
According to Wiebe (1978), “progress in barley improvement depends on a
supply of good genes and on breeding techniques for assembling these into superior
genotypes.” Until the concept and successful advent of molecular genetics
and nonsexual gene transfer in barley by three separate research laboratories in
1994, genetic improvement of barley was limited to traditional plant breeding
practices. The primary sources of genotypic variation for barley breeding prior
to 1994 included existing cultivars, breeding lines, mutations, and exotic gene
sources. The latter consisted of landraces of cultivated barley (Hordeum vulgare
subsp. vulgare) and genotypes within the related subspecies H. vulgare subsp.
spontaneum. H. bulbosum represented a secondary gene pool source but has limited
use, due to sterility in the hybrids produced (Bothmer et al. 1995). The
primary gene pool has been almost the sole source of allelic variation for producing
commercial cultivars with limited inputs from the secondary gene pool.
Enhancement of commercial barley germplasm to date has been limited to crossing
elite breeding lines and cultivars and will probably continue to be the primary
method of genotype improvement for at least the immediate future (Lemaux et al.
1999). However, the increased knowledge and technique improvements in mutagenic
breeding and transgenic cereal research exemplified by Wan and Lemaux
(1994) offer exciting opportunities to bypass many of the limitations of traditional
breeding practices and to provide access to more diverse sources of genes.
IMPROVING THE BARLEY CROP
Selection of barley plants having one or more desired characteristic(s) no doubt
occurred for eons prior to the science and knowledge of genes and heritability. It
can be assumed that in the beginning stages of agriculture it was recognized that
“like begets like,” resulting in the development of individual barley landraces
typical of a given area. It is likely that landraces developed in various regions
of the land were rarely, if ever, mixed until trade routes evolved between local
settlements and distant sections of the world. Throughout most of the history
of barley development and utilization, food and beverage production were the
important end uses. Therefore, those barleys that were palatable and/or were
successful in making beverages were probably those grains that were propagated.
As barley foods were gradually replaced by wheat and other grains, barley’s
primary use was shifted to animal feed, along with continued use in beverage