spp.) is a worldwide
from the Fertile Crescent
region of the Near East
. In 2007 world production of wheat was
607 million tons, making it the third most-produced cereal
tons) and rice
(651 million tons). Wheat
is a staple
used to make flour
for leavened, flat
and steamed breads, biscuits, cookies, cakes, breakfast cereal,
pasta, noodles, couscous
and for fermentation
to make beer, alcohol
, vodka, or biofuel
Wheat is planted to a limited extent as a forage
for livestock, and the straw can be used as fodder
for livestock or as a construction material
for roofing thatch
wheat supplies much of the world's dietary protein and food supply,
as many as one in every 100 to 200 people has Celiac disease, a condition which results
from an immune system response to a protein found in wheat:
gluten (based on figures for the United States).
Wheat has been cultivated domestically at least since 9,000 B.C.
and probably earlier. Domesticated Einkorn
wheat at Nevali Cori 40 miles northwest of Gobekli Tepe in Turkey has been
dated to 9,000 B.C.
However evidence for the exploitation of wild barley
has been dated to 23,000 B.C. and some say
this is also true of pre-domesticated wheat.
Wheat genetics is more complicated than that of most other
domesticated species. Some wheat species are diploid
, with two sets of chromosomes, but many are
, with four sets of
) or six (hexaploid
- Einkorn wheat (T. monococcum)
- Most tetraploid wheats (e.g. emmer and
durum wheat) are derived from wild emmer,
T. dicoccoides. Wild emmer is the result of a
hybridization between two diploid wild grasses, T. urartu
and a wild goatgrass such as Aegilops searsii or
Ae. speltoides. The
hybridization that formed wild emmer occurred in the wild, long
- Hexaploid wheats evolved in farmers' fields. Either
domesticated emmer or durum wheat hybridized with yet another wild
diploid grass (Aegilops
tauschii) to make the hexaploid
wheats, spelt wheat and bread wheat.
In traditional agricultural systems wheat populations often consist
, informal farmer-maintained
populations that often maintain high levels of morphological
diversity. Although landraces of wheat are no longer grown in
Europe and North America, they continue to be important elsewhere.
The origins of formal wheat breeding lie in the nineteenth century,
when single line varieties were created through selection of seed
from a single plant noted to have desired properties. Modern wheat
breeding developed in the first years of the twentieth century and
was closely linked to the development of Mendelian genetics
. The standard method
of breeding inbred wheat cultivars is by crossing two lines using
hand emasculation, then selfing or inbreeding the progeny.
Selections are identified
(shown to have the genes
responsible for the varietal differences) ten or more generations
before release as a variety or cultivar.
wheat cultivars should not be
confused with wheat cultivars deriving from standard plant breeding
or hybrid vigor (as in the familiar F1
hybrids of maize) occurs in common (hexaploid) wheat, but it is
difficult to produce seed of hybrid cultivars on a commercial scale
as is done with maize
because wheat flowers
are complete and normally self-pollinate
. Commercial hybrid wheat
seed has been produced using chemical hybridizing agents, plant growth regulators
interfere with pollen development, or naturally occurring cytoplasmic male sterility
systems. Hybrid wheat has been a limited commercial
success in Europe (particularly France), the USA
and South Africa.
The major breeding objectives include high grain yield, good
quality, disease and insect resistance and tolerance to abiotic
stresses include mineral, moisture and heat tolerance. The major
diseases in temperate environments include Fusarium head blight
, leaf rust and
, whereas in tropical areas
(also known as
Helminthosporium leaf blight).
Hulled versus free-threshing wheat
A mature wheat field
The four wild species of wheat, along with the domesticated
, have hulls. This
more primitive morphology (in evolutionary terms) consists of
toughened glumes that tightly enclose the grains, and (in
domesticated wheats) a semi-brittle rachis that breaks easily on
threshing. The result is that when threshed, the wheat ear breaks
up into spikelets. To obtain the grain, further processing, such as
milling or pounding, is needed to remove the hulls or husks. In
contrast, in free-threshing (or naked) forms such as durum wheat
and common wheat, the glumes are fragile and the rachis tough. On
threshing, the chaff breaks up, releasing the grains. Hulled wheats
are often stored as spikelets because the toughened glumes give
good protection against pests of stored grain.
Sack of wheat
There are many botanical classification systems used for wheat
species, discussed in a separate article on Wheat taxonomy
. The name of a wheat species
from one information source may not be the name of a wheat species
in another. Within a species, wheat cultivars are further
classified by wheat breeders and farmers in terms of growing
season, such as winter wheat
wheat, by gluten
content, such as hard wheat
(high protein content) vs. soft wheat (high starch content), or by
grain color (red, white or amber).
Major cultivated species of wheat
- Common wheat or
Bread wheat — (T. aestivum) A hexaploid species that is the most widely cultivated
in the world.
- Durum — (T.
durum) The only tetraploid form of wheat widely used today,
and the second most widely cultivated wheat.
- Einkorn — (T.
monococcum) A diploid species with wild
and cultivated variants. Domesticated at the same time as emmer
wheat, but never reached the same importance.
- Emmer — (T.
dicoccum) A tetraploid species,
cultivated in ancient times but no
longer in widespread use.
- Spelt — (T.
spelta) Another hexaploid species cultivated in limited
Classes used in the United States are
- Durum — Very hard,
translucent, light colored grain used to make semolina flour for pasta.
- Hard Red Spring — Hard, brownish, high
protein wheat used for bread and hard baked
goods. Bread Flour and high gluten flours are commonly made from
hard red spring wheat. It is primarily traded at the Minneapolis
- Hard Red Winter — Hard, brownish, mellow high
protein wheat used for bread, hard baked goods and as an adjunct in
other flours to increase protein in pastry flour for pie crusts.
Some brands of unbleached all-purpose flours are commonly made from
hard red winter wheat alone. It is primarily traded by the Kansas City Board of Trade. One
variety is known as "turkey red wheat", and was brought to Kansas
by Mennonite immigrants from Russia.
- Soft Red Winter — Soft, low protein wheat used
for cakes, pie crusts, biscuits, and muffins. Cake flour, pastry
flour, and some self-rising flours with baking powder and salt added for example, are
made from soft red winter wheat. It is primarily traded by the Chicago Board of
- Hard White — Hard, light colored, opaque,
chalky, medium protein wheat planted in dry, temperate areas. Used
for bread and brewing.
- Soft White — Soft, light colored, very low
protein wheat grown in temperate moist areas. Used for pie crusts
and pastry. Pastry flour, for example, is sometimes made from soft
white winter wheat.
Red wheats may need bleaching, therefore white wheats usually
command higher prices than red wheats on the commodities
As a food
Raw wheat can be powdered into flour
germinated and dried creating malt
; crushed or
cut into cracked wheat; parboiled (or steamed), dried, crushed and
de-branned into bulgur
; or processed into
, pasta, or roux
. Wheat is a major ingredient in such foods as
bread, porridge, crackers, biscuits, Muesli
pancakes, pies, pastries, cakes, cookies, muffins, rolls,
doughnuts, gravy, boza
(a fermented beverage
), and breakfast cereals
, Cream of
, Shredded Wheat
100 grams of hard red winter wheat contain about 12.6 grams of
, 1.5 grams of total fat
, 71 grams of carbohydrate
(by difference), 12.2 grams of
, and 3.2 mg of iron
(17% of the daily requirement); the same weight of
hard red spring wheat contains about 15.4 grams of protein
, 1.9 grams of total fat
68 grams of carbohydrate
difference), 12.2 grams of dietary fiber
3.6 mg of iron (20% of the daily requirement). USDA National Nutrient Database for Standard
, Release 19 (2006)
, a protein found in wheat (and other
), cannot be tolerated by people
with celiac disease
(an autoimmune disorder
in ~1% of Indo-European
Much of the carbohydrate fraction of wheat is starch
. Wheat starch is an important commercial
product of wheat, but second in economic value to wheat gluten
. The principal parts of wheat
flour are gluten and starch. These can be separated in a kind of
home experiment, by mixing flour and water to form a small ball of
dough, and kneading it gently while rinsing it in a bowl of water.
The starch falls out of the dough and sinks to the bottom of the
bowl, leaving behind a ball of gluten.
Roughly 1% of the population has coeliac
(also written as celiac) disease
—a condition that is caused by an adverse
reaction to gliadin
, a gluten
found in wheat (and similar proteins of the tribe Triticeae
which includes other species such as barley
). Upon exposure to gliadin, the enzyme
modifies the protein, and the immune system cross-reacts with the
bowel tissue, causing an inflammatory
. That leads to flattening of the lining of the
, which interferes with the absorption
The only effective treatment is a lifelong gluten-free diet
. While the disease is
caused by a reaction to wheat proteins, it is not the same as
Wheat output in 2005
Harvested wheat grain that enters trade is classified according to
grain properties for the purposes of the commodities market
. Wheat buyers use the
classifications to help determine which wheat to purchase as each
class has special uses. Wheat producers determine which classes of
wheat are the most profitable to cultivate with this system.
Wheat is widely cultivated as a cash crop
because it produces a good yield per unit area, grows well in a
even with a
moderately short growing season
yields a versatile, high-quality flour
widely used in baking
. Most breads
are made with wheat flour, including many
breads named for the other grains they contain like most rye
breads. The popularity of
foods made from wheat flour creates a large demand for the grain,
even in economies with significant food surpluses
Utensil made of dry wheat branches for
loaves of bread
In 2007 there was a dramatic rise in the price of wheat due to
freezes and flooding in the northern hemisphere and a drought in
Australia. Wheat futures in September, 2007 for December and March
delivery had risen above $9.00 a bushel, prices never seen before.
There were complaints in Italy about the high price of pasta. This
followed a wider trend of escalating food prices around the globe,
driven in part by climatic conditions such as drought in Australia,
the diversion of arable land
uses (such as producing government-subsidised bio-oil crops), and
later by some food-producing nations placing bans or restrictions
on exports in order to satisfy their own consumers.
Other drivers affecting wheat prices include the movement to bio
fuels (in 2008, a third of corn crops in the US are expected to be
devoted to ethanol production) and rising incomes in developing countries
, which is causing a
shift in eating patterns from predominantly rice to more meat based
diets (a rise in meat production equals a rise in grain consumption
- seven kilograms of grain is required to produce one kilogram of
Production and consumption statistics
global per capita wheat consumption was 67 kg, with the
highest per capita consumption (239 kg) found in Kyrgyzstan.
Unlike rice, wheat production is more widespread globally though
China's share is almost one-sixth of the world.
Wheat spikelet with the three anthers
While winter wheat lies dormant during a winter freeze, wheat
normally requires between 110 and 130 days between planting and
harvest, depending upon climate, seed type, and soil
conditions.Crop management decisions require the knowledge of stage
of development of the crop. In particular, spring fertilizer
applied at specific stages of plant development.
For example, current recommendations often indicate the second
application of nitrogen be done when the ear (not visible at this
stage) is about 1 cm in size (Z31 on Zadoks scale
). Knowledge of stages is also
interesting to identify periods of higher risk, in terms of
climate. For example, the meiosis
extremely susceptible to low temperatures (under 4 °C) or high
temperatures (over 25 °C). Farmers also benefit from knowing when
the flag leaf (last leaf) appears as this leaf represents about 75%
of photosynthesis reactions during the grain-filling period and as
such should be preserved from disease or insect attacks to ensure a
Several systems exist to identify crop stages, with the Feekes
being the most widely used. Each scale is a standard
system which describes successive stages reached by the crop during
the agricultural season.
Estimates of the amount of wheat production lost owing to plant
diseases vary between 10-25% in Missouri. A wide range of organisms
infect wheat, of which the most important are viruses and
Wheat is used as a food plant by the larvae
including The Flame
, Rustic Shoulder-knot
, Setaceous Hebrew Character
futures are traded on the Chicago Board of
Trade, Kansas City
Board of Trade, and Minneapolis Grain Exchange, and have delivery dates in March (H), May (K),
July (N), September (U), and December (Z).
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Russian Wheat on the Great Plains of the UNited States,"
Journal of Global History 3 (2008), 203-225
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Wheat Starch. Retrieved August 11, 2008.
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Victoria Sizemore Long in The Kansas City Star
September 28, 2007
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Press story by Colleen Barry, September 13, 2007 By COLLEEN
BARRY – Sep 13, 2007
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CompareShares April 2, 2008
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Delivery Dates on Wikinvest
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