Schriften zu Genetischen Ressourcen - Genres

Diversity in barley (Hordeum vulgare)
A number of such “key” genes have faced a heavy selection pressure in the early
phases of domestication or later when adapting to other areas. Some of these genes
in barley are:
• brittle rachis: regulated by two genes (Btr1 and Btr2), it is one of the major traits
to distinguish between Oriental and Occidental barley types;
• covered and naked kernels: regulated by a single recessive gene;
• seed dormancy: quantitative inheritance;
• growth habit (spring or winter types): regulated by three genes;
• kernel row (two- or six-rowed types): regulated by one major gene.
The Fertile Crescent area in the Middle East is variable due to climatic, altitudinal,
and habitat differences. This is reflected in the large morphological, physiological and
functional adaptability in ssp. spontaneum, which facilitated colonisation of primary
and secondary habitats in a range of most diverse environments (GRANER et al.
2002). Already at an early stage of domestication, a first differentiation of the genetic
diversity took place. The success of domestication and early cultivation spread rapidly
from the original areas. Seed material was brought by man to various areas
along with the cultivation practices. Barley cultivation reached Spain ca. 7,000 years
BP (Before Present), N Africa and Ethiopia ca. 8,000 years BP and northern Europe
ca. 6,000 years BP. In each new place where cultivation was brought the material
was exposed to new climatic and edaphic conditions. Due to the initial large genetic
variation in barley together with accumulation of new mutants and recombinants, the
crop became locally adapted. This has been a gradual process over millennia and it
is the basis for the creation of a multitude of locally adapted, genetically variable
landraces.
Over the years and in different regions there has also been conscious selection by
farmers for various criteria, such as taste, texture and other quality characters as well
as for yield. Since barley is a crop with multipurpose uses selection has been made
for the various uses further adding to diversity in older and newer lines. The major
uses are:
• human consumption – here naked kernels are preferred, still used particularly in
high altitude areas of C Asia;
• feed – selection for particularly high protein content lines has been made;
• malt – brewing is a very old knowledge to man (at least 4,000-5,000 years BP in
Egypt), promoting high enzymatic activity;
• health products – such as pearled barley in SE Asia, barley for tea production in
Japan, and “barley grass” (seedlings of barley) in Europe.
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