Principles of Plant Genetics and Breeding

Taxonomy
Kingdom Plantae
Subkingdom Tracheobionta
Superdivision Spermatophyta
Division Magnoliophyta
Class Lilliopsida
Subclass Commelinidae
Order Cyperales
Family Poaceae
Genus Triticum L.
Species Triticum aestivum L.
Economic importance
Wheat is the most important cereal grain crop in the
world. It is the principal cereal grain crop used for food
consumption in the USA and most parts of the world.
In the US, it usually ranks fourth after corn, hay, and
soybean, in that order of importance. Wheat is grown
commercially in nearly every state in the US, with
a concentration of production in the Great Plains, an
area spanning the states from Texas to Montana. US
Department of Agriculture (USDA) production trends
indicate that in 1866 wheat was harvested from an area
of 15.4 million acres, yielding an average of 11 bushels
per acre (see Appendix 2 for conversion rates of units).
By 1950, production occurred on 61.6 million acres,
with an average yield of 16.5 bushels/acre. In 1990, the
acreage was 69.2 million acres, with a yield average of
39.5 bushels/acre. The Central and Southern Plains
(Texas, Oklahoma, and Kansas, among others) produces
more than the Northern Plains (e.g., Montana,
North Dakota), with the two regions accounting for
two-thirds of US wheat production and about 80% of
wheat acreage. Kansas leads all states in wheat production.
Hard white wheat is also grown in the Central and
Northern Plains.
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Breeding wheat
World production of wheat in 2001 was 583.9 million
metric tons, occurring on 219.5 million acres.
World wheat consumption in that period was 590.6
million metric tons. Developing countries (excluding
those in Eastern Europe or the former Soviet Union)
account for nearly 50% of the world’s wheat production,
the leading producers being China, India, Turkey,
Pakistan, and Argentina. The success of wheat production
in these countries is credited to the impact of the
Green Revolution that occurred in the 1960s and
1970s. In 2000, China produced 111.9 million metric
tons while India produced 26.5 metric tons. Latin
America and Asia (excluding China and India) each
produce about 20 million metric tons a year. Wheat is
produced in Europe, including the United Kingdom,
Denmark, the Netherlands, Belgium, Switzerland, and
West Germany.
Origin and history
The origin of wheat is believed to be southwestern
Asia. A cross between wild emmer wheat (Triticum
dicoccoides) and Aegilops squarrosa, a grass, produced a
spelt-like plant. This suggests that the common or bread
wheat (T. aestivum) is descended from a cross between
spelt and the progenitor of Persian wheat (T. persicum).
Persian wheat occurs in the wild in the Russian
Caucasus. The Persian wheat probably is descended
from the wheat of the Neolithic Swiss lake dwellers,
which in turn might have originated from a cross
between einkorn and a grass, Agropyron triticum.
Archeological findings indicate that emmer wheat was
cultivated before 7000 bc. Similarly, wheat was cultivated
in Europe in prehistoric times. In the US, wheat
was first cultivated along the Atlantic coast in the early
17th century, moving westwards as the country was
settled.