Wheat
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{{For|the indie rock group|Wheat (band)}}
{{Taxobox
| name =
| regnum = [[Plantae]]
| divisio = [[Flowering plant|Magnoliophyta]]
| classis = [[Liliopsida]]
| ordo = [[Poales]]
| familia = [[Poaceae]]
| subfamilia = [[Pooideae]]
| tribus = [[Triticeae]]
| genus = '''''Triticum'''''
| genus_authority = [[Carolus Linnaeus|L.]]
| subdivision_ranks = Species
| subdivision =
''[[Common wheat|T. aestivum]]''<br />
''T. aethiopicum''<br />
''T. araraticum''<br />
''[[einkorn wheat|T. boeoticum]]''<br />
''T. carthlicum''<br />
''[[Common is wheat|T. compactum]]''<br />
''[[Emmer|T. dicoccoides]]''<br />
''[[Emmer|T. dicoccon]]''<br />
''[[durum|T. durum]]''<br />
''T. ispahanicum''<br />
''T. karamyschevii''<br />
''T. macha''<br />
''T. militinae''<br />
''[[Einkorn|T. monococcum]]''<br />
''T. polonicum''<br />
''[[Spelt|T. spelta]]''<br />
''[[common wheat|T. sphaerococcum]]''<br />
''[[Triticum timopheevii|T. timopheevii]]''<br />
''T. turanicum''<br />
''T. turgidum''<br />
''T. urartu''<br />
''T. vavilovii''<br />
''T. zhukovskyi''<br />
<small>References:<br /> [http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=42236 ITIS 42236] 2002-09-22</small>
}}
'''Wheat''' (''Triticum'' spp.)<ref name=Belderok>Belderok, Bob & Hans Mesdag & Dingena A. Donner. (2000) ''Bread-Making Quality of Wheat''. Springer. p.3. ISBN 0-7923-6383-3.</ref> is a worldwide cultivated [[Poaceae|grass]] from the [[Levant]] area of the [[Middle East]]. Globally, after [[maize]], wheat is the second most produced food among the [[cereal|cereal crops]]; [[rice]] ranks third.<ref>{{Citation
| last1 = U. S. Department of Agriculture| first1 =
| author1-link =
| last2 = | first2 =
| last3 = | first3 = M.
| last4 = | first4 =
| title = Annual World Production Summary, ''Grains''
| date =
| year = 2003
| url =http://www.usda.gov/wps/portal/!ut/p/_s.7_0_A/7_0_1OB?parentnav=AGRICULTURE&navid=CROP_PRODUCTION&navtype=RT
| accessdate = 2007-09-04 }}
</ref> Wheat [[Caryopsis|grain]] is a [[staple food]] used to make [[flour]] for leavened, flat and steamed [[bread]]s; [[cookie]]s, [[cake]]s, [[pasta]], [[noodles]] and [[couscous]];<ref>Cauvain, Stanley P. & Cauvain P. Cauvain. (2003) ''Bread Making''. CRC Press. p. 540. ISBN 1-85573-553-9.</ref> and for [[fermentation (food)|fermentation]] to make [[beer]],<ref>Palmer, John J. (2001) ''How to Brew''. Defenestrative Pub Co. p. 233. ISBN 0-9710579-0-7.</ref> [[alcohol]], [[vodka]]<ref>Neill, Richard. (2002) ''Booze: The Drinks Bible for the 21st Century''. Octopus Publishing Group - Cassell Illustrated. p. 112. ISBN 1-84188-196-1.</ref> or [[biofuel]].<ref>''Department of Agriculture Appropriations for 1957: Hearings ... 84th Congress. 2d Session''. ''United States. Congress. House. Appropriations''. 1956. p. 242.</ref> Wheat is planted to a limited extent as a [[Fodder|forage crop]] for [[livestock]], and the [[straw]] can be used as [[fodder]] for livestock or as a construction material for roofing [[thatch]].<ref>Smith, Albert E. (1995) ''Handbook of Weed Management Systems''. Marcel Dekker. p. 411. ISBN 0-8247-9547-4.</ref><ref name=CVDE>Bridgwater, W. & Beatrice Aldrich. (1966) ''The Columbia-Viking Desk Encyclopedia''. Columbia University. p. 1959.</ref>
Although wheat supplies much of the world's dietary protein and food supply, as many as one in every 100 to 200 persons in the [[United States]] has [[Coeliac disease]], a condition which results from an inappropriate immune system response to a protein found in wheat: [[gluten]].<ref>{{cite journal
| last = Fasano
| first = A
| authorlink =
| coauthors = Berti I, Gerarduzzi T, et al.
| title = Prevalence of celiac disease in at-risk and not-at-risk groups in the United States: a large multicenter study
| journal = Arch Intern Med.
| volume = 163
| issue = 3
| pages = 286–292
| publisher =
| location =
| date =
| url = http://archinte.ama-assn.org/cgi/content/abstract/163/3/286?view=abstract
| doi =
| id =
| accessdate =
| pmid = 12578508 }}</ref><ref>{{cite journal
| last = Presutti
| first = John
| authorlink =
| coauthors = et al.
| title = Celiac Disease
| journal = American Family Physician
| volume = 76
| issue = 12
| pages = 196–1802
| publisher =
| location =
| date = 2007-12-27
| url = http://www.aafp.org/afp/20071215/1795.html
| doi =
| id =
| accessdate = }}</ref><ref>Hill, I. D., Horvath, K., and Fasano, A., ''Epidemiology of celiac disease.'' 1: Am J Gastroenterol. 1995 Jan;90(1):163-4</ref>
== History ==
Wheat originated in [[Southwest Asia]] in the area known as the [[Fertile crescent]]. The genetic relationships between [[einkorn]] and [[emmer]] indicate that the most likely site of domestication is near [[Diyarbakır]] in [[Turkey]].<ref>Jorge Dubcovsky and Jan Dvorak, "Genome Plasticity a Key Factor in the Success of Polyploid Wheat Under Domestication", Science 316 [Issue 5853], p. 1862, 29 June 2007 </ref> These wild wheats were domesticated as part of the [[origins of agriculture]] in the Fertile Crescent. Cultivation and repeated harvesting and sowing of the grains of wild grasses led to the [[domestication]] of wheat through selection of mutant forms with tough ears which remained intact during harvesting, larger grains, and a tendency for the spikelets to stay on the stalk until harvested. <ref>"Seeking Agriculture's Ancient Roots", Science 316 [Issue 5853], p. 1830, 29 June 2007 </ref> Because of the loss of seed dispersal mechanisms, domesticated wheats have limited capacity to propagate in the wild.<ref name=Smith>Smith, C. Wayne. (1995) ''Crop Production''. John Wiley and Sons. pp. 60-62. ISBN 0-471-07972-3.</ref>
The cultivation of wheat began to spread beyond the Fertile Crescent during the [[Neolithic|Neolithic period]]. The oldest wheat found thus far is from Çatalhöyük, a Neolithic settlement in southern [[Anatolia]]. The wheat samples discovered were found to be 8,500 years old.<ref>[http://www.todayszaman.com/tz-web/detaylar.do?load=detay&link=145271&bolum=101 Oldest wheat found in Çatalhöyük], [[Today's Zaman]], June 22nd 2008</ref> By 5,000 years ago, wheat had reached [[Ethiopia]], [[India]], [[Great Britain]], [[Ireland]] and [[Spain]]. A millennium later it reached [[China]].<ref name=Smith /> Three thousand years ago agricultural cultivation with horse drawn plows increased cereal grain production, as did the use of [[seed drill]]s to replace broadcast sowing in the 18th century. Yields of wheat continued to increase, as new land came under cultivation and with improved agricultural husbandry involving the use of [[fertilizer]]s, [[threshing machines]] and reaping machines, [[tractor]]-drawn cultivators and planters, and better varieties (see [[green revolution]] and [[Norin 10 wheat]]). With population growth rates falling in the more technologically advanced countries, while yields continue to rise, the area devoted to wheat may now begin to decline for the first time in modern [[human history]].<ref>[http://www.economist.com/science/displaystory.cfm?story_id=5323362&no_na_tran=1 Ears of plenty: The story of wheat], [[The Economist]], December 24th 2005, pp. 28-30</ref>
But now in 2007 wheat stocks have reached their lowest since 1981, and 2006 was the first year in which the world consumed more wheat than the world produced - a gap that is continuously widening as the requirement for wheat increases beyond production.
== Genetics ==
[[Image:usdaeinkorn1.jpg|thumb|120px|Spikelets of a hulled wheat, [[einkorn]]]]
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 stable [[polyploidy|polyploids]], with four sets of chromosomes ([[tetraploid]]) or six ([[hexaploid]]).<ref name=Hancock>Hancock, James F. (2004) ''Plant Evolution and the Origin of Crop Species''. CABI Publishing. ISBN 0-85199-685-X.</ref>
* [[Einkorn]] wheat (''T. monococcum'') is diploid.<ref name=Belderok />
* Most tetraploid wheats (e.g. [[emmer]] and [[durum|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 ''[[Aegilops speltoides|Ae. speltoides]]''. The hybridization that formed wild emmer occurred in the wild, long before domestication.<ref name=Hancock />
* 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 [[common wheat|bread wheat]].<ref name=Hancock />
== Plant breeding ==
{{main|physiological and molecular wheat breeding}}
[[Image:WheatPennsylvania1943.jpg|thumb|Wheat]]
[[Image:Wheat P1210892.jpg|thumb|Wheat]]
In traditional agricultural systems wheat populations often consist of [[landraces]], 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.<ref name=Bajaj />
F1 hybrid wheat cultivars should not be confused with wheat cultivars deriving from standard plant breeding. [[Heterosis]] 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-pollination|self-pollinate]].<ref name=Bajaj>Bajaj, Y. P. S. (1990) ''Wheat''. Springer. pp. 161-63. ISBN 3-540-51809-6.</ref> Commercial hybrid wheat seed has been produced using chemical hybridizing agents, plant growth regulators that selectively 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.<ref>Basra, Amarjit S. (1999) ''Heterosis and Hybrid Seed Production in Agronomic Crops''. Haworth Press. pp. 81-82. ISBN 1-56022-876-8.</ref>
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 [[stem rust]], whereas in tropical areas [[spot blotch (wheat)]] (also known as Helminthosporium leaf blight).
See [[physiological and molecular wheat breeding]]
== Hulled versus free-threshing wheat ==
[[Image:Wheat-haHula-ISRAEL2.JPG|thumb|A mature wheat field, in northern Israel]]
The four wild species of wheat, along with the domesticated varieties [[einkorn]],<ref name=Potts>Potts, D. T. (1996) ''Mesopotamia Civilization: The Material Foundations'' Cornell University Press. p. 62. ISBN 0-8014-3339-8.</ref> [[emmer]]<ref>Nevo, Eviatar & A. B. Korol & A. Beiles & T. Fahima. (2002) ''Evolution of Wild Emmer and Wheat Improvement: Population Genetics, Genetic Resources, and Genome...''. Springer. p. 8. ISBN 3-540-41750-8.</ref> and [[spelt]],<ref>Vaughan, J. G. & P. A. Judd. (2003) ''The Oxford Book of Health Foods''. Oxford University Press. p. 35. ISBN 0-19-850459-4.</ref> have hulls (in German, ''Spelzweizen''). This more primitive morphology 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.<ref name=Potts />
== Naming ==
{{details|Wheat taxonomy}}
[[Image:Wheat in sack.jpg|thumb|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]] vs. spring wheat,<ref name=CVDE /> by [[gluten]] content, such as hard wheat (high protein content) vs. soft wheat (high starch content), or by grain color (red, white or amber).
In [[British English]] wheat may be referred to as '''corn'''.<ref>
{{cite book
|title=Usage and Abusage: A Guide to Good English
|first=Eric
|last=Partridge
|coauthors=Janet Whitcut (ed.)
|isbn=0393037614
|location=New York
|publisher=W.W. Norton, 1995
|year=1995
|edition=1st American ed.
|pages=p.82
|url=http://books.google.com/books?id=icnKIlILT4oC&pg=PA82&vq=corn&source=gbs_search_r&cad=1_1&sig=gDb63y1bG3c40htw8rMw_1_v4GI
}}
</ref>
===Major cultivated species of wheat===
*'''[[Common wheat]]''' or '''Bread wheat''' — (''T. aestivum'') A [[ploidy|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. dicoccon'') A [[ploidy|tetraploid]] species, cultivated in ancient times but no longer in widespread use.
*'''[[Spelt]]''' — (''T. spelta'') Another hexaploid species cultivated in limited quantities.
=== In the United States ===<!-- This section is linked from [[Bowbells, North Dakota]] -->
[[Image:Wheat harvest.jpg|thumb|Wheat harvest on the Palouse.]]
[[Image:CombineWheat0654.JPG|thumb|Combining wheat in Hemingway, South Carolina.]]
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 Grain Exchange]].
*'''[[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 Trade]].
*'''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.
Hard wheats are harder to process and red wheats may need bleaching. Therefore, soft and white wheats usually command higher prices than hard and red wheats on the commodities market.
==As a food==
{{nutritionalvalue
| name=Wheat germ, crude
| kJ=1506
| protein=23.15 g
| fat=9.72 g
| carbs=51.8 g
| fiber=13.2 g
| sugars=
| glucose=
| fructose=
| iron_mg=6.26
| opt1n=[[Manganese]] 13.301 mg
| opt1v=
| calcium_mg=39
| magnesium_mg=239
| phosphorus_mg=842
| potassium_mg=892
| zinc_mg=12.29
| vitC_mg=
| pantothenic_mg=0.05
| vitB6_mg=1.3
| folate_ug=281
| thiamin_mg=1.882
| riboflavin_mg=0.499
| niacin_mg=6.813
| right=1
| source_usda=1 }}
[[Image:Sa-cracked-wheat.jpg|thumb|left|150px|Cracked wheat]]
Raw wheat can be powdered into [[flour]], germinated and dried creating [[malt]], crushed and de-branned into cracked wheat, parboiled (or steamed), dried, crushed and de-branned into [[bulgur]], or processed into [[semolina]], [[pasta]], or [[roux]]. They are a major ingredient in such foods as [[bread]], [[breakfast cereal]]s (e.g. [[Wheatena]], [[Cream of Wheat]], [[Shredded Wheat]]), [[porridge]], [[Cracker (food)|cracker]]s, [[biscuit]]s, [[pancake]]s, [[cake]]s, [[gravy]] and [[boza]] (a fermented beverage).
===Nutrition===
100 grams of hard red winter wheat contain about 12.6 grams of [[protein]], 1.5 grams of total [[fat]], 71 grams of [[carbohydrate]] (by difference), 12.2 grams of dietary [[fiber]], 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]] (by difference), 12.2 grams of dietary [[fiber]], and 3.6 mg of [[iron]] (20% of the daily requirement).<ref name=USDA_ARS>[http://www.nal.usda.gov/fnic/foodcomp/search/ USDA National Nutrient Database for Standard Reference], Release 19 (2006)</ref>
[[Gluten]], a protein found in wheat (and other [[Triticeae]]), cannot be tolerated by people with [[celiac disease]] (an autoimmune disorder in ~1% of Indo-European populations).<ref name=VanHeelWest>{{cite journal | author = van Heel D, West J | title = Recent advances in coeliac disease | url = http://gut.bmjjournals.com/cgi/content/full/55/7/1037 | journal = Gut | volume = 55 | issue = 7 | pages = 1037–46 | year = 2006 | pmid = 16766754 | doi = 10.1136/gut.2005.075119}}</ref>
===Health concerns===
{{Main|Gluten sensitivity}}
{{Main|Coeliac disease}}
Roughly 1% of the population[http://www.coeliac.co.uk/other/TextOnly/?ContentID=252&FontSize=9] has coeliac or celiac disease—a condition that is caused by an adverse [[immune system]] reaction to [[gliadin]], a [[gluten]] protein found in wheat (and similar proteins of the [[tribe (biology)|tribe]] [[Triticeae]] which includes other cultivars such as [[barley]] and [[rye]]). Upon exposure to gliadin, the enzyme [[tissue transglutaminase]] modifies the protein, and the immune system cross-reacts with the bowel tissue, causing an [[inflammation|inflammatory reaction]]. That leads to flattening of the lining of the small intestine, which [[malabsorption|interferes with the absorption]] of nutrients. 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 allergy]].
== Economics ==
{| class="wikitable" align="right" width="200px"
! colspan=2|Top Ten Wheat Producers — 2005 (million metric ton)
|-
| {{CHN}} || align="right" | 96
|-
| {{IND}} || align="right" | 72
|-
| {{USA}} || align="right" | 57
|-
| {{RUS}} || align="right" | 46
|-
| {{FRA}} || align="right" | 37
|-
| {{CAN}} || align="right" | 26
|-
| {{AUS}}|| align="right" | 24
|-
| {{GER}} || align="right" | 24
|-
| {{PAK}} || align="right" | 22
|-
| {{TUR}} || align="right" | 21
|-
|'''World Total''' || align="right" | '''626'''
|-
|colspan=2 style="font-size:90%" |''Source: [[UN Food & Agriculture Organisation]] (FAO)''<ref>[http://www.fao.org/es/ess/top/commodity.html?lang=en&item=15&year=2005 Major Food And Agricultural Commodities And Producers - Countries By Commodity<!-- Bot generated title -->]</ref>
|}
[[Image:2005wheat.PNG|thumb|left|Wheat output in 2005]]
Harvested wheat grain that enters trade is classified according to grain properties (see below) for the purposes of the [[commodity markets|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 [[temperate climate]] even with a moderately short [[growing season]], and yields a versatile, high-quality [[flour]] that is widely used in [[baking]]. Most [[bread]]s are made with wheat flour, including many breads named for the other grains they contain like most [[rye]] and [[oat]] breads. The popularity of foods made from wheat flour creates a large demand for the grain, even in economies with significant food [[economic surplus|surpluses]].
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.<ref>[http://www.kansascity.com/business/story/295713.html "Wheat futures again hit new highs"] article by Victoria Sizemore Long in ''[[The Kansas City Star]]'' September 28, 2007</ref> There were complaints in Italy about the high price of pasta.<ref>[http://ap.google.com/article/ALeqM5gn9LSyRa1AbT3rICpaVcHU36XjCQ "Wheat Prices Send Italian Pasta Costs Up"] [[Associated Press]] story by Colleen Barry, September 13, 2007
By COLLEEN BARRY – Sep 13, 2007</ref> 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 to other 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 beef. <ref>[http://www.compareshares.com.au/fras38.php "Broker picks in the soft commodities sector"] in ''[[CompareShares]]'' April 2, 2008</ref>
==Production and consumption statistics==
{{Main|International wheat production statistics}}
In 1997, global per capita wheat consumption was 101 kg, with the highest per capita consumption (623 kg) found in [[Denmark]].
Unlike rice, wheat production is more widespread globally though China's share is almost one-sixth of the world.
==Agronomy==
[[Image:Spiklet.jpg|thumb|Wheat spikelet with the three anthers sticking out.]]
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]] applications, [[herbicide]]s, [[fungicide]]s, [[growth regulator]]s are typically 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 stage is 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 good yield.
Several systems exist to identify crop stages, with the [[Feekes scale|Feekes]] and [[Zadoks scale]]s being the most widely used. Each scale is a standard system which describes successive stages reached by the crop during the agricultural season.
*Wheat at the anthesis stage (face and side view)
{|
|[[Image:WheatFlower1.jpg|thumb|none|]]
|[[Image:WheatFlower3.JPG|thumb|none|]]
|}
===Diseases===
{{Main|Wheat diseases|List of wheat diseases}}
Estimates of the amount of wheat production lost owing to plant diseases vary between 10-25% in Missouri.<ref>[http://muextension.missouri.edu/explore/agguides/crops/g04319.htm G4319 Wheat Diseases in Missouri, MU Extension<!-- Bot generated title -->]</ref> A wide range of organisms infect wheat, of which the most important are viruses and fungi.
===Pests===
Wheat is used as a food plant by the [[larva]]e of some [[Lepidoptera]] ([[butterfly]] and [[moth]]) species including [[Flame (moth)|The Flame]], [[Rustic Shoulder-knot]], [[Setaceous Hebrew Character]] and [[Turnip Moth]].
==See also==
{{commons}}
*[[Bran]]
*[[Chaff]]
*[[Husk]]
*[[Wheat germ oil]]
*[[Starch]]
==References==
{{reflist}}
==Further reading==
*Bonjean, A.P., and W.J. Angus (editors). The World Wheat Book: a history of wheat breeding. Lavoisier Publ., Paris. 1131 pp. (2001). ISBN 2-7430-0402-9.
* {{cite book
| author= S. Padulosi, K. Hammer, J. Heller, editors
| date=1996
| title= Hulled wheats
| series=Promoting the conservation and use of underutilized and neglected crops. 4
| publisher= International Plant Genetic Resources Institute, Rome, Italy
|url= http://www.bioversityinternational.org/Publications/pubfile.asp?ID_PUB=54
}}
*Garnsey Peter, Grain for Rome, in Garnsey P., Hopkins K., Whittaker C. R. (editors), Trade in the Ancient Economy, Chatto & Windus, London 1983
*Jasny Naum, ''The daily bread of ancient Greeks and Romans'', Ex Officina Templi, Brugis 1950
*Jasny Naum, ''The Wheats of Classical Antiquity, J''. Hopkins Press, Baltimore 1944
*Heiser Charles B., ''Seed to civilisation. The story of food,'' Harvard University Press, Harvard Mass. 1990
*Harlan Jack R., ''Crops and man'', American Society of Agronomy, Madison 1975
*Saltini Antonio, ''I semi della civiltà. Grano, riso e mais nella storia delle società umane'', Prefazione di Luigi Bernabò Brea, Avenue Media, Bologna 1996
*Sauer Jonathan D., ''Geography of Crop Plants. A Select Roster'', CRC Press, Boca Raton
==External links==
*[http://www.flickr.com/photos/jaco/sets/72157604419390265/ Photos of wheat fields]
*[http://www.abc.net.au/catalyst/stories/s1913579.htm Watch Australian science documentary on developing drought-resistant wheat]
*[http://www.wheatfoods.org/ Wheat Foods Council] Est. 1972
*[http://www.wheatworld.org/ NAWG] — Web site of the [[National Association of Wheat Growers]]
*[http://www.cimmyt.org/ CIMMYT] — Web site of the [[International Maize and Wheat Improvement Center]]
*[http://www.hort.purdue.edu/newcrop/crops/wheat.html Triticum species] at [[Purdue University]]
*[http://www.genetics.org/cgi/content/full/168/2/1087 A Workshop Report on Wheat Genome Sequencing]
*[http://www.genome.org/cgi/content/full/10/10/1509 Molecular Genetic Maps in Wild Emmer Wheat]
*[http://www.skyways.org/orgs/fordco/malin/ Winter Wheat in the Golden Belt of Kansas] by James C. Malin, University of Kansas, 1944
*[http://digital.library.unt.edu/permalink/meta-dc-1510:1 ''Varieties of club wheat''] hosted by the [http://digital.library.unt.edu/browse/department/govdocs/ UNT Government Documents Department]
{{Wheat}}
{{Cereals}}
[[Category:Energy crops]]
[[Category:Wheat| ]]
[[Category:Cereals]]
[[Category:Crops]]
[[Category:Staple foods]]
{{Link FA|es}}
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