Wheat is grown on a larger area of land than any other food crop (220.7 million hectares or 545 million acres in 2021). World trade in wheat is greater than that of all other crops combined. In 2021, world wheat production was 771 milliontonnes (850 million short tons), making it the second most-produced cereal aftermaize (known as corn in North America and Australia; wheat is often called corn in countries including Britain).[4] Since 1960, world production of wheat and other grain crops has tripled and is expected to grow further through the middle of the 21st century. Global demand for wheat is increasing because of the usefulness ofgluten to the food industry.
A: Plant; B ripe ear of corn; 1spikelet before flowering; 2 the same, flowering and spread, enlarged; 3 flowers withglumes; 4stamens; 5pollen; 6 and 7 ovaries with juice scales; 8 and 9 parts of the scar; 10 fruit husks; 11, 12, 13 seeds, natural size and enlarged; 14 the same cut up, enlarged.
Wheat is a stout grass of medium to tall height. Its stem is jointed and usually hollow, forming a straw. There can be many stems on one plant. It has long narrow leaves, their bases sheathing the stem, one above each joint. At the top of the stem is the flower head, containing some 20 to 100 flowers. Each flower contains both male and female parts.[5] The flowers arewind-pollinated, with over 99% of pollination events beingself-pollinations and the restcross-pollinations.[6] The flower is housed in a pair of small leaflikeglumes. The two (male)stamens and (female)stigmas protrude outside the glumes. The flowers are grouped intospikelets, each with between two and six flowers. Each fertilisedcarpel develops into a wheat grain or berry; botanically acaryopsis fruit, it is often called a seed. The grains ripen to a golden yellow; a head of grain is called an ear.[5]
Leaves emerge from the shoot apicalmeristem in a telescoping fashion until the transition to reproduction i.e. flowering.[7] The last leaf produced by a wheat plant is known as the flag leaf. It is denser and has a higherphotosynthetic rate than other leaves, to supplycarbohydrate to the developing ear. In temperate countries the flag leaf, along with the second and third highest leaves on the plant, supply the majority of carbohydrate in the grain; their condition is critical for crop yield.[8][9] Wheat is unusual in having morestomata on the upper (adaxial) side of the leaf, than on the under (abaxial) side.[10] It has been theorised that this might be an effect of having been cultivated longer than any other plant.[11]Winter wheat generally produces up to 15 leaves per shoot, and spring wheat up to 9;[12] winter crops may have up to 35tillers (shoots) per plant (depending on cultivar).[12]
Wheatroots are among the deepest of arable crops, extending as far down as 2 metres (6 ft 7 in).[13] While the roots of a wheat plant are growing, the plant accumulates an energy store in its stem, in the form offructans,[14] which helps the plant to yield under drought and disease pressure,[15] but there is a trade-off between root growth and stem non-structural carbohydrate reserves. Root growth is likely to be prioritised in drought-adapted crops, while stem non-structural carbohydrate is prioritised in varieties developed for countries where disease is a bigger issue.[16]
Depending on variety, wheat may beawned or not. Producing awns incurs a cost in grain number,[17] but wheat awns photosynthesise more efficiently than leaves with regards to water usage,[18] so awns are much more frequent in varieties of wheat grown in hot drought-prone countries than those in temperate countries. For this reason, awned varieties could become more widespread due toclimate change. In Europe, wheat'sclimate resilience has declined.[19]
Hunter-gatherers in West Asia harvested wild wheats for thousands of years before they weredomesticated,[20] perhaps as early as 21,000 BC,[21] but they formed a minor component of their diets.[22] In this phase of pre-domestication cultivation, early cultivars were spread around the region and slowly developed the traits that came to characterise their domesticated forms.[23]
Repeated harvesting and sowing of the grains ofwild grasses led to the creation of domestic strains, as mutant forms ('sports') of wheat were more amenable to cultivation. In domesticated wheat, grains are larger, and the seeds (inside thespikelets) remain attached to the ear by a toughenedrachis during harvesting.[24] In wild strains, a more fragile rachis allows the ear toshatter easily, dispersing the spikelets.[25] Selection for larger grains and non-shattering heads by farmers might not have been deliberately intended, but simply have occurred because these traits made gathering the seeds easier; nevertheless such 'incidental' selection was an important part of cropdomestication. As the traits that improve wheat as a food source involve the loss of the plant's naturalseed dispersal mechanisms, highly domesticated strains of wheat cannot survive in the wild.[26]
Einkorn and emmer are considered two of thefounder crops cultivated by the first farming societies inNeolithic West Asia.[27] These communities also cultivated naked wheats (T. aestivum andT. durum) and a now-extinct domesticated form ofZanduri wheat (T. timopheevii),[32] as well as a wide variety of other cereal and non-cereal crops.[33] Wheat was relatively uncommon for the first thousand years of the Neolithic (whenbarley predominated), but became a staple after around 8500 BC.[33] Early wheat cultivation did not demand much labour. Initially, farmers took advantage of wheat's ability to establish itself inannual grasslands by enclosing fields against grazing animals and re-sowing stands after they had been harvested, without the need to systematically remove vegetation or till the soil.[34] They may also have exploited natural wetlands and floodplains to practice décrue farming, sowing seeds in the soil left behind by receding floodwater.[35][36][37] It was harvested withstone-bladedsickles.[38] The ease of storing wheat and other cereals led farming households to become gradually more reliant on it over time, especially after they developed individual storage facilities that were large enough to hold more than a year's supply.[39]
Domestic wheat was quickly spread to regions where its wild ancestors did not grow naturally. Emmer was introduced to Cyprus as early as 8600 BC and einkornc. 7500 BC;[45][46] emmer reachedGreece by 6500 BC,Egypt shortly after 6000 BC, andGermany andSpain by 5000 BC.[47] "The early Egyptians were developers ofbread and the use of the oven and developed baking into one of the first large-scale food production industries."[48] By 4000 BC, wheat had reached theBritish Isles andScandinavia.[49][50][51] Wheat was also cultivated inIndia around 3500 BC.[52] Wheat likely appeared inChina's lowerYellow River around 2600 BC.[53]
The oldest evidence forhexaploid wheat is throughDNA analysis of wheat seeds from around 6400–6200 BC atÇatalhöyük.[54] As of 2023,[update] the earliest known wheat with sufficient gluten for yeasted breads is from a granary atAssiros inMacedonia dated to 1350 BC.[55] Wheat continued to spread across Europe and to theAmericas in theColumbian exchange. In the British Isles, wheat straw (thatch) was used for roofing in theBronze Age, remaining in common use until the late 19th century.[56][57] White wheat bread was historically a high status food, but during the nineteenth century it became in Britain an item of mass consumption, displacingoats,barley andrye from diets in the North of the country.[58] After 1860, the expansion ofwheat production in the United States flooded the world market, lowering prices by 40%, and made a major contribution to the nutritional welfare of the poor.[59]
Sumeriancylinder seal impression dating toc. 3200 BC showing anensi and his acolyte feeding a sacred herd wheat stalks;Ninurta was an agricultural deity and, in a poem known as the "SumerianGeorgica", he offers detailed advice on farming
Some wheat species arediploid, with two sets ofchromosomes, but many are stablepolyploids, with four sets (tetraploid) or six (hexaploid).[60] Einkorn is diploid (AA, two complements of seven chromosomes, 2n=14).[61] Most tetraploid wheats (e.g. emmer anddurum wheat) are derived from wild emmer. Wild emmer is itself the result of a hybridization between two diploid wild grasses,T. urartu and a wild goatgrass such asAe. speltoides.[62] The hybridization that formed wild emmer (AABB, four complements of seven chromosomes in two groups, 4n=28) occurred in the wild, long before domestication, and was driven bynatural selection. Hexaploid wheats evolved in farmers' fields as wild emmer hybridized with another goatgrass,Ae. squarrosa orAe. tauschii, to make thehexaploid wheats includingbread wheat.[60][63]
A 2007molecular phylogeny of the wheats gives the following not fully-resolvedcladogram of major cultivated species; the large amount of hybridisation makes resolution difficult. Markings like "6N" indicate thepolyploidy of each species:[60]
During 10,000 years of cultivation, numerous forms of wheat, many of themhybrids, have developed under a combination ofartificial andnatural selection. This complexity and diversity of status has led to much confusion in the naming of wheats.[64][65]
The wild species of wheat, along with the domesticated varietieseinkorn,[66] emmer[67] andspelt,[68] 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. Hulled wheats are often stored as spikelets because the toughened glumes give good protection against pests of stored grain.[66] In free-threshing (or naked) forms, such as durum wheat and common wheat, the glumes are fragile and the rachis tough. On threshing, thechaff breaks up, releasing the grains.[69]
Widely used today, and the second most widely cultivated wheat.[70]
Emmer (T. turgidum subsp.dicoccum andT. t. conv.durum)
A species cultivated inancient times, derived from wild emmer,T. dicoccoides, but no longer in widespread use.[72]
Khorasan or Kamut (T. turgidum ssp. turanicum, also calledT. turanicum)
An ancient grain type; Khorasan is a historical region in modern-day Afghanistan and the northeast of Iran. The grain is twice the size of modern wheat and has a rich nutty flavor.[73]
Classification of wheat greatly varies by the producing country.[75]
Argentina's grain classes were formerly related to the production region or port of shipment:Rosafe (grown inSanta Fe province, shipped throughRosario),Bahia Blanca (grown inBuenos Aires andLa Pampa provinces and shipped throughBahia Blanca),Buenos Aires (shipped through theport of Buenos Aires). While mostly similar to the US Hard Red Spring wheat, the classification caused inconsistencies, so Argentina introduced three new classes of wheat, with all names using a prefixTrigo Dura Argentina (TDA) and a number.[76] The grain classification inAustralia is within the purview of its National Pool Classification Panel. Australia chose to measure the protein content at 11%moisture basis.[77]The decisions on the wheat classification inCanada are coordinated by the Variety Registration Office of theCanadian Food Inspection Agency. As in the US system, the eight classes inWestern Canada and six classes inEastern Canada are based on colour, season, and hardness. Uniquely, Canada requires that the varieties should allow for purely visual identification.[78]The classes used in theUnited States are named by colour, season, and hardness.[79][80][81]
Wheat is a significant source ofvegetable proteins in human food, having a relatively high protein content compared to other major cereals.[90] However, wheat proteins have a low quality for human nutrition, according to theDIAAS protein quality evaluation method.[91][92] Though they contain adequate amounts of the other essential amino acids, at least for adults, wheat proteins are deficient in theessential amino acidlysine.[89][93] Because the gluten proteins present inendosperm are particularly poor in lysine,white flours are more deficient in lysine than are whole grains.[89] Plant breeders have sought to develop lysine-rich wheat varieties, without success, as of 2017[update].[94] Supplementation with proteins from other food sources (mainlylegumes) is used to compensate for this deficiency.[95][89]
Wheat's share (brown) of world crop production fell in the 21st century.
In 2023, world wheat production was 799 million tonnes, led by China, India, and Russia which collectively provided 42.4% of the world total.[109] As of 2019[update],the largest exporters were Russia (32 million tonnes), United States (27), Canada (23) and France (20), while the largest importers were Indonesia (11 million tonnes), Egypt (10.4) and Turkey (10.0).[110] In 2021, wheat was grown on 220.7 million hectares or 545 million acres worldwide, more than any other food crop.[111]World trade in wheat is greater than for all other crops combined.[112]Global demand for wheat is increasing due to the uniqueviscoelastic and adhesive properties ofgluten proteins, which facilitate the production of processed foods, whose consumption is increasing as a result of the worldwide industrialization process andwesternization of diets.[89][113]
Wheat became a central agriculture endeavor in the worldwideBritish Empire in the 19th century, and remains of great importance in Australia, Canada and India.[115] In Australia, with vast lands and a limited work force, expanded production depended on technological advances, especially irrigation and machinery. By the 1840s there were 900 growers inSouth Australia. They used "Ridley's Stripper", a reaper-harvester perfected byJohn Ridley in 1843,[116] to remove the heads of grain. In Canada, modern farm implements made large scale wheat farming possible from the late 1840s. By 1879,Saskatchewan was the center, followed byAlberta,Manitoba andOntario, as the spread of railway lines allowed easy exports to Britain. By 1910, wheat made up 22% of Canada's exports, rising to 25% in 1930 despite the sharp decline in prices during theGreat Depression.[117] Efforts to expand wheat production in South Africa, Kenya and India were stymied by low yields and disease. However, by 2000 India had become the second largest producer of wheat in the world.[118] In the 19th century the American wheat frontier moved rapidly westward. By the 1880s 70% of American exports went to British ports. The first successfulgrain elevator was built in Buffalo in 1842.[119] The cost of transport fell rapidly. In 1869 it cost 37 cents to transport a bushel of wheat fromChicago toLiverpool; in 1905 it was 10 cents.[120]
In the 20th century, global wheat output expanded about 5-fold, but until about 1955 most of this reflected increases in wheat crop area, with lesser (about 20%) increases in yield per unit area. After 1955 however, there was a ten-fold increase in the rate of wheat yield improvement per year, and this allowed global wheat production to increase. Thus technological innovation and scientific crop management withsynthetic nitrogen fertilizer, irrigation and wheat breeding were the main drivers of wheat output growth in the second half of the century. There were some significant decreases in wheat crop area, for instance in North America.[121] Better seed storage and germination ability (and hence a smaller requirement to retain harvested crop for next year's seed) is another 20th-century technological innovation. In medieval England, farmers saved one-quarter of their wheat harvest as seed for the next crop, leaving only three-quarters for food and feed consumption. By 1999, the global average seed use of wheat was about 6% of output.[122]
In the 21st century,global warming is reducing wheat yield in some places.[123]War[124] andtariffs have disrupted trade.[125] Between 2007 and 2009, concern was raised that wheat production would peak, in thesame manner as oil,[126][127][128] possibly causing sustained price rises.[129][130][131] However, at that time global per capita food production had been increasing steadily for decades.[132]
Wheat is anannual crop. It can be planted in autumn and harvested in early summer aswinter wheat in climates that are not too severe, or planted in spring and harvested in autumn asspring wheat. It is normally planted aftertilling the soil byploughing and thenharrowing to kill weeds and create an even surface. The seeds are then scattered on the surface, ordrilled into the soil in rows. Winter wheat lies dormant during a winter freeze. It needs to develop to a height of 10 to 15 cm before the cold intervenes, so as to be able to survive the winter; it requires a period with the temperature at or near freezing, itsdormancy then being broken by the thaw or rise in temperature. Spring wheat does not undergo dormancy. Wheat requires a deepsoil, preferably aloam with organic matter, and available minerals including soil nitrogen, phosphorus, and potassium. An acid andpeaty soil is not suitable. Wheat needs some 30 to 38 cm of rain in the growing season to form a good crop of grain.[133]
The farmer may intervene while the crop is growing to addfertilizer, water byirrigation, or pesticides such asherbicides to kill broad-leaved weeds orinsecticides to kill insect pests. The farmer may assess soil minerals, soil water, weed growth, or the arrival of pests to decide timely and cost-effective corrective actions, and crop ripeness and water content to select the right moment to harvest. Harvesting involvesreaping, cutting the stems to gather the crop; andthreshing, breaking the ears to release the grain; both steps are carried out by acombine harvester. The grain is then dried so that it can be stored safe frommould fungi.[133]
Wheat developmental stages on theBBCH and Zadok's scales
Wheat normally needs between 110 and 130 days between sowing and harvest, depending upon climate, seed type, and soil conditions. Optimal crop management requires that the farmer have a detailed understanding of each stage of development in the growing plants. In particular, springfertilizers,herbicides,fungicides, andgrowth regulators are typically applied only at specific stages of plant development. For example, it is currently recommended that the second application of nitrogen is made when the ear (not visible at this stage) is about 1 cm in size (Z31 onZadoks scale). Knowledge of stages is important to identify periods of higher risk from the climate. Farmers benefit from knowing when the 'flag leaf' (last leaf) appears, as it represents about 75% of photosynthesis during the grain filling period, and so should be preserved from disease or insect attacks to ensure a good yield. Several systems exist to identify crop stages, with theFeekes and Zadoks scales being the most widely used. Each scale describes successive stages reached by the crop during the season.[134] For example, the stage of pollen formation from the mother cell, and the stages betweenanthesis and maturity, are vulnerable to high temperatures, made worse by water stress.[135]
Technological advances in soil preparation and seed placement at planting time, use ofcrop rotation andfertilizers to improve plant growth, and advances in harvesting have combined to promote wheat as a viable crop. When the use ofseed drills replaced broadcasting sowing of seed in the 18th century, productivity increased.. Yields per unit area increased as crop rotations were applied to land that had long been in cultivation, and the use of fertilizers became widespread.[136]
Some large wheat grain-producing countries have significant losses after harvest at the farm, because of poor roads, inadequate storage technologies, inefficient supply chains and farmers' inability to bring the produce into retail markets dominated by small shopkeepers. Some 10% of total wheat production is lost at farm level, another 10% is lost because of poor storage and road networks, and more is lost at the retail level.[142]
In thePunjab region of the Indian subcontinent, as well as North China, irrigation has been a major contributor to increased output. More widely over the last 40 years, a massive increase in fertilizer use together with increased availability of semi-dwarf varieties in developing countries, has greatly increased yields per hectare.[143] In developing countries, use of (mainly nitrogenous) fertilizer increased 25-fold in this period. However, farming systems rely on much more than fertilizer and breeding to improve productivity. A good illustration of this is Australian wheat growing in the southern winter cropping zone, where, despite low rainfall (300 mm), wheat cropping is successful even with relatively little use of nitrogenous fertilizer. This is achieved by crop rotation with leguminous pastures. The inclusion of acanola crop in the rotations has boosted wheat yields by a further 25%.[144] In these low rainfall areas, better use of available soil-water (and better control of soil erosion) is achieved by retaining the stubble after harvesting and by minimizing tillage.[145]
There are many wheat diseases, mainly caused by fungi, bacteria, andviruses.[147]Plant breeding to develop new disease-resistant varieties, and sound crop management practices are important for preventing disease. Fungicides, used to prevent the significant crop losses from fungal disease, can be a significant variable cost in wheat production. Estimates of the amount of wheat production lost owing to plant diseases vary between 10 and 25% in Missouri.[148] A wide range of organisms infect wheat, of which the most important are viruses and fungi.[149]
A historically significant disease of cereals including wheat, though commoner inrye isergot; it is unusual among plant diseases in also causing sickness in humans who ate grain contaminated with the fungus involved,Claviceps purpurea.[155]
Among insect pests of wheat is thewheat stem sawfly,a chronic pest in the Northern Great Plains of the United States and in theCanadian Prairies.[156]Wheat is the food plant of thelarvae of someLepidoptera (butterfly andmoth) species includingthe flame,rustic shoulder-knot,setaceous Hebrew character andturnip moth. Early in the season, many species of birds and rodents feed upon wheat crops. These animals can cause significant damage to a crop by digging up and eating newly planted seeds or young plants. They can also damage the crop late in the season by eating the grain from the mature spike. Recent post-harvest losses in cereals amount to billions of dollars per year in the United States alone, and damage to wheat by various borers, beetles and weevils is no exception.[157] Rodents can also cause major losses during storage, and in major grain growing regions, field mice numbers can sometimes build up explosively to plague proportions because of the ready availability of food.[158] To reduce the amount of wheat lost to post-harvest pests,Agricultural Research Service scientists have developed an "insect-o-graph", which can detect insects in wheat that are not visible to the naked eye. The device uses electrical signals to detect the insects as the wheat is being milled. The new technology is so precise that it can detect 5–10 infested seeds out of 30,000 good ones.[159]
In traditional agricultural systems, wheat populations consist oflandraces, informal and often diverse farmer-maintained populations. Landraces of wheat continue to be important outside America and Europe.Formal wheat breeding began in the nineteenth century, when single line varieties were created by selecting seed from a plant with desired properties. Modern wheat breeding developed early in the twentieth century, linked to the development ofMendelian 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 genetically ten or more generations before release as a cultivar.[160]
Major breeding objectives include highgrain yield, good quality,disease- and insect resistance and tolerance to abiotic stresses, including mineral, moisture and heat tolerance.[161][162] Wheat has been the subject ofmutation breeding, with the use ofgamma-,x-rays,ultraviolet light, and harsh chemicals. Since 1960, hundreds of varieties have been created through these methods, mostly in populous countries such as China.[161] Bread wheat with high grain iron and zinc content has been developed through gamma radiation breeding,[163] and through conventional selection breeding.[164] International wheat breeding is led by the International Maize and Wheat Improvement Center in Mexico.ICARDA is another major public sector international wheat breeder, but it was forced to relocate from Syria to Lebanon in theSyrian Civil War.[165]
The presence of certain versions of wheat genes has been important for crop yields. Genes for the 'dwarfing' trait, first used by Japanese wheat breeders to produceNorin 10 short-stalked wheat, have had a huge effect on wheat yields worldwide, and were major factors in the success of theGreen Revolution in Mexico and Asia, an initiative led byNorman Borlaug.[166] Dwarfing genes enable the carbon that is fixed in the plant during photosynthesis to be diverted towards seed production, and reduce lodging,[167] when a tall ear stalk falls over in the wind.[168] By 1997, 81% of the developing world's wheat area was planted to semi-dwarf wheats, giving both increased yields and better response to nitrogenous fertilizer.[169]
T. turgidum subsp.polonicum, known for its longerglumes and grains, has been bred into main wheat lines for its grain size effect, and likely has contributed these traits toT. petropavlovskyi and the Portugueselandrace groupArrancada.[170] As with many plants,MADS-box influences flower development, and more specifically, as with other agricultural Poaceae, influences yield. Despite that importance, as of 2021[update] little research has been done into MADS-box and other such spikelet and flower genetics in wheat specifically.[170]
The world record wheat yield is about 17tonnes perhectare (15,000 pounds per acre), reached in New Zealand in 2017.[171] A project in the UK, led byRothamsted Research has aimed to raise wheat yields in the country to 20 t/ha (18,000 lb/acre) by 2020, but in 2018 the UK record stood at 16 t/ha (14,000 lb/acre), and the average yield was just 8 t/ha (7,100 lb/acre).[172][173]
Different strains have been infected with thestem rust fungus. The strains bred to be resistant have their leaves unaffected or relatively unaffected by the fungus.
In 2003 the first resistance genes against fungal diseases in wheat were isolated.[184][185] In 2021, novel resistance genes were identified in wheat againstpowdery mildew andwheat leaf rust.[186][187]Modified resistance genes have been tested in transgenic wheat and barley plants.[188]
Because wheat self-pollinates, creatinghybrid seed to provideheterosis, hybrid vigor (as in F1 hybrids of maize), is extremely labor-intensive; the high cost of hybrid wheat seed has kept farmers from adopting them widely[189][190] despite nearly 90 years of effort.[191][160] Commercial hybrid wheat seed has been produced using chemical hybridizing agents,plant growth regulators that interfere with pollen development, or naturally occurringcytoplasmic male sterility systems. Hybrid wheat has been a limited commercial success in France, the United States and South Africa.[192]
Synthetic hexaploids made by crossing the wild goatgrass wheat ancestorAegilops tauschii,[193] and otherAegilops,[194] with durum wheats are being deployed, increasing the genetic diversity of cultivated wheats.[195][196][197]
Modern bread wheat varieties have beencross-bred to contain greater amounts of gluten.[198][199] However, a 2020 study found no changes in albumin/globulin and gluten content between 1891 and 2010.[200]
Stomata (or leaf pores) are involved in both uptake of carbon dioxide gas from the atmosphere and water vapor losses from the leaf due to watertranspiration. Basic physiological investigation of these gas exchange processes has yielded carbonisotope based method used for breeding wheat varieties with improved water-use efficiency. These varieties can improve crop productivity in rain-fed dry-land wheat farms.[201]
The complex genome of wheat has made its improvement difficult. Comparison of hexaploid wheat genomes using a range of chromosome pseudomolecule and molecular scaffold assemblies in 2020 has enabled the resistance potential of its genes to be assessed. Findings include the identification of "a detailed multi-genome-derived nucleotide-binding leucine-rich repeat protein repertoire" which contributes to disease resistance, while the geneSm1 provides a degree of insect resistance,[202] for instance against theorange wheat blossom midge.[203]
In 2010, 95% of the genome of Chinese Spring line 42 wheat was decoded.[204] This genome was released in a basic format for scientists and plant breeders to use but was not fully annotated.[205] In 2012, an essentially complete gene set of bread wheat was published.[206]Random shotgun libraries of total DNA and cDNA from theT. aestivum cv. Chinese Spring (CS42) were sequenced to generate 85 Gb of sequence (220 million reads) and identified between 94,000 and 96,000 genes.[206] In 2018, a more complete Chinese Spring genome was released by a different team.[207] In 2020, 15 genome sequences from various locations and varieties around the world were reported, with examples of their own use of the sequences to localize particular insect and disease resistance factors.[208]Wheat Blast Resistance is controlled byR genes which are highly race-specific.[154]
The Dutch artistVincent van Gogh created the seriesWheat Fields between 1885 and 1890, consisting of dozens of paintings made mostly in different parts of rural France. They depict wheat crops, sometimes with farm workers, in varied seasons and styles, sometimes green, sometimes at harvest.Wheatfield with Crows was one of his last paintings, and is considered to be among his greatest works.[210][211]
In 1967, the American artistThomas Hart Benton made his oil on wood paintingWheat, showing a row of uncut wheat plants, occupying almost the whole height of the painting, between rows of freshly-cut stubble. The painting is held by theSmithsonian American Art Museum.[212]
In 1982, the American conceptual artistAgnes Denes grew a two-acre field of wheat atBattery Park, Manhattan. Theephemeral artwork has been described as an act of protest. The harvested wheat was divided and sent to 28 world cities for an exhibition entitled "The International Art Show for the End of World Hunger".[213]
^Mencken, H. L. (1984).The American language: an inquiry into the development of English in the United States (4th ed.). New York:Alfred A. Knopf. p. 122.ISBN0-394-40075-5.Corn, in orthodox English, means grain for human consumption, especially wheat, e.g., the Corn Laws.
^Pajević, Slobodanka; Krstić, Borivoj; Stanković, Živko; Plesničar, Marijana; Denčić, Srbislav (1999). "Photosynthesis of Flag and Second Wheat Leaves During Senescence".Cereal Research Communications.27 (1/2):155–162.doi:10.1007/BF03543932.JSTOR23786279.
^Araus, J. L.; Tapia, L.; Azcon-Bieto, J.; Caballero, A. (1986). "Photosynthesis, Nitrogen Levels, and Dry Matter Accumulation in Flag Wheat Leaves During Grain Filling".Biological Control of Photosynthesis. pp. 199–207.doi:10.1007/978-94-009-4384-1_18.ISBN978-94-010-8449-9.
^Singh, Sarvjeet; Sethi, G.S. (1995). "Stomatal Size, Frequency and Distribution inTriticum Aestivum,Secale Cereale and Their Amphiploids".Cereal Research Communications.23 (1/2):103–108.JSTOR23783891.
^Richter, Tobias; Maher, Lisa A. (2013). "Terminology, process and change: reflections on the Epipalaeolithic of South-west Asia".Levant.45 (2):121–132.doi:10.1179/0075891413Z.00000000020.S2CID161961145.
^Fuller, Dorian Q.; Willcox, George; Allaby, Robin G. (2011). "Cultivation and domestication had multiple origins: arguments against the core area hypothesis for the origins of agriculture in the Near East".World Archaeology.43 (4):628–652.doi:10.1080/00438243.2011.624747.S2CID56437102.
^Luo, M.-C.; Yang, Z.-L.; You, F. M.; Kawahara, T.; Waines, J. G.; Dvorak, J. (2007). "The structure of wild and domesticated emmer wheat populations, gene flow between them, and the site of emmer domestication".Theoretical and Applied Genetics.114 (6):947–959.doi:10.1007/s00122-006-0474-0.PMID17318496.S2CID36096777.
^Scott, James C. (2017). "The Domestication of Fire, Plants, Animals, and ... Us".Against the Grain: A Deep History of the Earliest States. New Haven: Yale University Press. p. 66.ISBN978-0-3002-3168-7. Retrieved19 March 2023.The general problem with farming — especially plough agriculture — is that it involves so much intensive labor. One form of agriculture, however, eliminates most of this labor: 'flood-retreat' (also known as décrue or recession) agriculture. In flood-retreat agriculture, seeds are generally broadcast on the fertile silt deposited by an annual riverine flood.
^Graeber, David; Wengrow, David (2021).The dawn of everything: a new history of humanity. London: Allen Lane. p. 235.ISBN978-0-241-40242-9.
^Lucas, Leilani; Colledge, Sue; Simmons, Alan; Fuller, Dorian Q. (1 March 2012). "Crop introduction and accelerated island evolution: archaeobotanical evidence from 'Ais Yiorkis and Pre-Pottery Neolithic Cyprus".Vegetation History and Archaeobotany.21 (2):117–129.Bibcode:2012VegHA..21..117L.doi:10.1007/s00334-011-0323-1.S2CID129727157.
^Jarrige, Jean-François; Meadow, Richard H (1980). "The antecedents of civilization in the Indus Valley".Scientific American.243 (2):122–137.
^Long, Tengwen; Leipe, Christian; Jin, Guiyun; Wagner, Mayke; Guo, Rongzhen; et al. (2018). "The early history of wheat in China from 14C dating and Bayesian chronological modelling".Nature Plants.4 (5):272–279.doi:10.1038/s41477-018-0141-x.PMID29725102.S2CID19156382.
^Nelson, Scott Reynolds (2022).Oceans of Grain: How American Wheat Remade the World. Basic Books. pp. 3–4.ISBN978-1-5416-4646-9.
^abcdGolovnina, K. A.; Glushkov, S. A.; Blinov, A. G.; Mayorov, V. I.; Adkison, L. R.; Goncharov, N. P. (12 February 2007). "Molecular phylogeny of the genus Triticum L".Plant Systematics and Evolution.264 (3–4). Springer:195–216.Bibcode:2007PSyEv.264..195G.doi:10.1007/s00606-006-0478-x.S2CID39102602.
^abBelderok, Robert 'Bob'; Mesdag, Hans; Donner, Dingena A. (2000).Bread-Making Quality of Wheat. Springer. p. 3.ISBN978-0-7923-6383-5.
^Nevo, E. (29 January 2002).Evolution of Wild Emmer and Wheat Improvement. Berlin ; New York: Springer Science & Business Media. p. 8.ISBN3-540-41750-8.
^"Field Crop Information". College of Agriculture and Bioresources, University of Saskatchewan. Archived fromthe original on 18 October 2023. Retrieved10 July 2023.
^Khlestkina, Elena K.; Röder, Marion S.; Grausgruber, Heinrich; Börner, Andreas (2006). "A DNA fingerprinting-based taxonomic allocation of Kamut wheat".Plant Genetic Resources.4 (3):172–180.doi:10.1079/PGR2006120.S2CID86510231.
^Anderson, Patricia C. (1991). "Harvesting of Wild Cereals During the Natufian as seen from Experimental Cultivation and Harvest of Wild Einkorn Wheat and Microwear Analysis of Stone Tools". In Bar-Yosef, Ofer (ed.).Natufian Culture in the Levant. International Monographs in Prehistory. Ann Arbor, Michigan: Berghahn Books. p. 523.
^ab"Whole Grain Fact Sheet". European Food Information Council. 1 January 2009. Archived fromthe original on 20 December 2016. Retrieved6 December 2016.
^abcd"Celiac disease". World Gastroenterology Organisation Global Guidelines. July 2016. Retrieved7 December 2016.
^abc"Definition and Facts for Celiac Disease". The National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, US Department of Health and Human Services, Bethesda, MD. 2016. Retrieved5 December 2016.
^Slafer, G.A.; Satorre, E.H. (1999).Wheat: Ecology and Physiology of Yield Determination. Haworth Press. pp. 322–323.ISBN1-56022-874-1.
^Saini, H.S.; Sedgley, M.; Aspinall, D. (1984). "Effect of heat stress during floral development on pollen tube growth and ovary anatomy in wheat (Triticum aestivum L.)".Australian Journal of Plant Physiology.10 (2):137–144.doi:10.1071/PP9830137.
^Gautam, P.; Dill-Macky, R. (2012). "Impact of moisture, host genetics andFusarium graminearum isolates on Fusarium head blight development and trichothecene accumulation in spring wheat".Mycotoxin Research.28 (1):45–58.doi:10.1007/s12550-011-0115-6.PMID23605982.S2CID16596348.
^Verma, Shailender Kumar; Kumar, Satish; Sheikh, Imran; et al. (3 March 2016). "Transfer of useful variability of high grain iron and zinc from Aegilops kotschyi into wheat through seed irradiation approach".International Journal of Radiation Biology.92 (3):132–139.doi:10.3109/09553002.2016.1135263.PMID26883304.S2CID10873152.
^Krattinger, Simon G.; Lagudah, Evans S.; Spielmeyer, Wolfgang; Singh, Ravi P.; Huerta-Espino, Julio; McFadden, Helen; et al. (6 March 2009). "A Putative ABC Transporter Confers Durable Resistance to Multiple Fungal Pathogens in Wheat".Science.323 (5919):1360–1363.Bibcode:2009Sci...323.1360K.doi:10.1126/science.1166453.ISSN0036-8075.PMID19229000.
![Production of wheat (2019)[108]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aProduction_of_wheat_(2019).svg)
.jpg)
_inside_a_wheat_kernel_(cropped).jpg)
