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User:Quarter1001/sandbox
{{short description|Genus of grass cultivated as a food crop}}
{{Distinguish|Maze}}
{{about|the commonly grown cereal grain}}
{{redirect|Corn}}
{{Use mdy dates|date=January 2016}}
{{Speciesbox
| name = Maize
| image = Koeh-283.jpg
| image_caption = Includes male and female flowers
| image_alt = [[Botanical illustration]] showing male and female flowers
| genus = Zea (plant)
| species = mays
| status = LC
| status_system = IUCN3.1
| status_ref = <ref>Contreras, A., Ruíz Corral, J.A., Menjívar, J., Aragón Cuevas, F., González Ledesma, M. & Sánchez, J.J. 2019. ''Zea mays''. The [[IUCN Red List]] of Threatened Species 2019: e.T77726273A77726310. https://dx.doi.org/10.2305/IUCN.UK.2019-2.RLTS.T77726273A77726310.en. Accessed on 28 October 2022.</ref>
| authority = [[Carl Linnaeus|L.]]
}}

'''Maize''' ({{IPAc-en|m|eɪ|z}} {{respell|MAYZ}}; ''Zea mays'' subsp. ''mays'', from {{langx|es|maíz}} after {{langx|tnq|mahis}}<ref>{{Cite web |last= |first= |last2= |title=maíz|url=https://dle.rae.es/maíz |access-date=2023-01-14 |website=[[Diccionario de la lengua española]] - Edición del Tricentenario |language=es}}</ref>), also known as '''corn''' in [[North American English|North American-]] and [[Australian English|Australian-]] English, is a [[cereal grain]] first domesticated by [[indigenous peoples of Mexico|indigenous peoples in southern Mexico]] about 10,000 years ago.<ref>{{cite web |url=http://learn.genetics.utah.edu/content/selection/corn/ |title=The Evolution of Corn |publisher=[[University of Utah]] HEALTH SCIENCES |access-date=2 January 2016}}</ref><ref name="benz">{{cite journal |title=Archaeological evidence of teosinte domestication from Guilá Naquitz, Oaxaca |journal=[[Proceedings of the National Academy of Sciences]] |volume=98 |issue=4 |pages=2104–2106 |doi=10.1073/pnas.98.4.2104 |pmid=11172083 |pmc=29389 |year=2001 |last1=Benz |first1=B. F. |bibcode=2001PNAS...98.2104B |doi-access=free }}</ref> The leafy stalk of the plant gives rise to [[inflorescence]]s (or "tassels") which produce [[pollen]] and separate [[ovule|ovuliferous]] inflorescences called [[ear (botany)|ears]] that when fertilized yield [[Corn kernels|kernels]] or seeds, which are [[fruit|botanical fruits]].<ref>{{Cite news|url=http://articles.extension.org/pages/36971/please-settle-a-dispute-is-sweet-corn-a-vegetable-or-a-grain-what-is-the-difference-how-about-field-|archive-url=https://web.archive.org/web/20180621113745/http://articles.extension.org/pages/36971/please-settle-a-dispute-is-sweet-corn-a-vegetable-or-a-grain-what-is-the-difference-how-about-field-|archive-date=21 June 2018|title=Please settle a dispute. Is sweet corn a vegetable or a grain? What is the difference? How about field corn? - eXtension|work=USDA [[National Institute of Food and Agriculture]], New Technologies for Ag Extension project|access-date=3 March 2018|language=en}}</ref><ref>{{cite web |last1=Chodosh |first1=Sara |title=The bizarre botany that makes corn a fruit, a grain, and also (kind of) a vegetable |url=https://www.popsci.com/is-corn-fruit-vegetable-or-grain/ |website=[[Popular Science]]|access-date=24 February 2022 |date=8 July 2021}}</ref> The term ''maize'' is preferred in formal, scientific, and international usage as the [[common name]] because this refers specifically to this one grain whereas ''corn'' refers to any principal [[cereal]] crop cultivated in a country. For example, in North America and Australia ''corn'' is often used for maize, but in England and Wales it can refer to [[wheat]] or [[barley]], and in Scotland and Ireland to [[oat]]s.

Maize has become a [[staple food]] in many parts of the world, with the [[List of most valuable crops and livestock products|total production of maize surpassing]] that of [[wheat]] or [[rice]]. In addition to being consumed directly by humans (often in the form of [[masa]]), maize is also used for [[corn ethanol]], [[animal feed]] and other [[:Category:Maize products|maize products]], such as [[corn starch]] and [[corn syrup]].<ref>{{cite web |last1=Foley |first1=Jonathon |title=It's Time to Rethink America's Corn System |url=https://www.scientificamerican.com/article/time-to-rethink-corn/ |website=[[Scientific American]]|access-date=18 February 2019}}</ref> The six major types of maize are [[dent corn]], [[flint corn]], [[pod corn]], [[popcorn]], [[flour corn]], and [[sweet corn]].<ref name="OxfordEncyclopedia">{{cite book|last=McLellan Plaisted|first=Susan|chapter=Corn|editor-last1=Smith|editor-first1=Andrew |title=The Oxford encyclopedia of food and drink in America |date=2013|publisher=Oxford University Press |location=New York, NY|isbn=9780199739226|edition=2nd|access-date=15 February 2023|url=https://www.oxfordreference.com/display/10.1093/acref/9780199734962.001.0001/acref-9780199734962-e-0218|quote=The use of the word "corn" for what is termed "maize" by most other countries is peculiar to the United States. Europeans who were accustomed to the names "wheat corn," "barley corn," and "rye corn" for other small-seeded cereal grains referred to the unique American grain maize as "Indian corn." The term was shortened to just "corn," which has become the American word for the plant of American genesis.}}</ref> Sugar-rich varieties called sweet corn are usually grown for human consumption as kernels, while [[field corn]] varieties are used for animal feed, various corn-based human food uses (including grinding into [[cornmeal]] or [[masa]], pressing into [[corn oil]], fermentation and distillation into alcoholic beverages like [[bourbon whiskey]]), and as feedstocks for the chemical industry. Maize is also used in making [[ethanol]] and other [[biofuel]]s.

Maize is widely cultivated throughout the world, and a greater weight of maize is produced each year than any other grain.<ref name=global/> In 2021, total world production was {{Convert|1.2|e9t|abbr=off}}. Maize is the most widely grown grain [[crop]] throughout the Americas, with {{Convert|384|e6t|abbr=off}} grown in the United States alone in 2021.{{citation needed|date=July 2022}} [[Genetically modified maize]] made up 85% of the maize planted in the United States in 2009.<ref name="GMOCompass">[http://www.gmo-compass.org/eng/agri_biotechnology/gmo_planting/341.genetically_modified_maize_global_area_under_cultivation.html Genetically modified plants: Global Cultivation Area Maize] {{webarchive|url=https://web.archive.org/web/20100812103002/http://www.gmo-compass.org/eng/agri_biotechnology/gmo_planting/341.genetically_modified_maize_global_area_under_cultivation.html|date=August 12, 2010}} [[GMO Compass]], March 29, 2010, retrieved August 10, 2010</ref> [[Corn subsidies in the United States|Subsidies in the United States]] help to account for its high level of cultivation of maize and its position as the largest producer in the world.<ref>{{Cite web|title=Corn Production By State 2021|url=https://worldpopulationreview.com/state-rankings/corn-production-by-state|access-date=2021-07-16|website=worldpopulationreview.com}}</ref>

== History ==

=== Pre-Columbian development ===
[[File:Guila Naquitz cave.jpg|thumb|Plant fragments dated to 4200&nbsp;BC found in the [[Guilá Naquitz Cave]] in [[Oaxaca]], Mexico, showed maize had already been [[domesticated]] from [[teosinte]].<ref name="benz" />]]
[[File:The Florentine Codex- Agriculture.tiff|thumb|right|Cultivation of maize in an illustration from the 16th c. [[Florentine Codex]]]]
[[File:Museo Nacional de Antropología - MAÍZ.jpg|thumb|right|Ancient Mesoamerican [[relief]], [[National Museum of Anthropology (Mexico)|National Museum of Anthropology of Mexico]]]]

Maize is a [[cultigen]]; human intervention is required for it to propagate. Whether or not the kernels fall off the cob on their own is a key piece of evidence used in archaeology to distinguish domesticated maize from its naturally-propagating [[teosinte]] ancestor.<ref name="benz" /> Genetic evidence can also be used to determine when various lineages split.<ref>{{Cite book|last=Blake|first=Michael|url=https://books.google.com/books?id=9YYkDQAAQBAJ&pg=PA27|title=Maize for the Gods: Unearthing the 9,000-Year History of Corn|date=2015-08-28|publisher=Univ of California Press|isbn=978-0-520-27687-1|language=en}}</ref>

Most historians believe maize was domesticated in the [[Tehuacán Valley matorral|Tehuacán Valley]] of Mexico.<ref>{{cite news|url=http://agron-www.agron.iastate.edu/Courses/agron212/readings/corn_history.htm |work=[[Iowa State University]], Department of Agronomy |title=Origin, History and Uses of Corn |date=February 11, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140223100251/http://agron-www.agron.iastate.edu/Courses/agron212/readings/corn_history.htm |archive-date=February 23, 2014 }}</ref> Recent research in the early 21st century has modified this view somewhat; scholars now indicate the adjacent [[Balsas River]] Valley of south-central Mexico as the center of domestication.<ref name="ReferenceA">{{cite journal |last1=Piperno |first1=Dolores R. |title=The Origins of Plant Cultivation and Domestication in the New World Tropics: Patterns, Process, and New Developments |journal=Current Anthropology |date=October 2011 |volume=52 |issue=S4 |pages=S453–S470 |doi=10.1086/659998 |s2cid=83061925 |quote=Recent studies in the Central Balsas River Valley of Mexico, maize's postulated cradle of origin, document the presence of maize phytoliths and starch grains at 8700 BP, the earliest date recorded for the crop (Piperno et al. 2009; Ranere et al. 2009). A large corpus of data indicates that it was dispersed into lower Central America by 7600 BP and had moved into the inter-Andean valleys of Colombia between 7000 and 6000 BP. Given the number of Cauca Valley, Colombia, sites that demonstrate early maize, it is likely that the inter-Andean valleys were a major dispersal route for the crop after it entered South America}}</ref>

An 2002 study by Matsuoka ''et al.''. has demonstrated that, rather than the multiple independent domestications model, all maize arose from a single domestication in southern Mexico about 9,000 years ago. The study also demonstrated that the oldest surviving maize types are those of the Mexican highlands. Later, maize spread from this region over the Americas along two major paths. This is consistent with a model based on the archaeological record suggesting that maize diversified in the highlands of Mexico before spreading to the lowlands.<ref name="Mat">{{cite journal |last1=Matsuoka |first1=Y. |year=2002 |title=A single domestication for maize shown by multilocus microsatellite genotyping |journal=[[Proceedings of the National Academy of Sciences]] |volume=99 |pages=6080–4 |doi=10.1073/pnas.052125199 |pmid=11983901 |last2=Vigouroux |first2=Y. |last3=Goodman |first3=M. M. |last4=Sanchez G. |first4=J. |last5=Buckler |first5=E. |last6=Doebley |first6=J. |issue=9 |pmc=122905 |display-authors=3|bibcode=2002PNAS...99.6080M|doi-access=free }}</ref><ref name="sciencenow">{{cite news |url=http://teosinte.wisc.edu/pdfs/YV_Directional_Evol.pdf |first=Yoshihiro |last=Matsuoka |title=Earliest Directional Evolution for Microsatellite Size in Maize |date=22 January 2003 |work=Science |access-date=3 March 2014}}</ref>

Archaeologist Dolores Piperno has said:<ref name="ReferenceA" />

{{blockquote|A large corpus of data indicates that [maize] was dispersed into lower Central America by 7600 BP [5600 BC] and had moved into the inter-Andean valleys of Colombia between 7000 and 6000 BP [5000–4000 BC]. |Dolores Piperno |''The Origins of Plant Cultivation and Domestication in the New World Tropics: Patterns, Process, and New Developments''<ref name="ReferenceA" />}}

Since then, even earlier dates have been published.<ref name="Pagán-JiménezGuachamín-Tello2015">{{cite journal |last1=Pagán-Jiménez |first1=Jaime R. |last2=Guachamín-Tello |first2=Ana M. |last3=Romero-Bastidas |first3=Martha E. |last4=Constantine-Castro |first4=Angelo R. |title=Late ninth millennium B.P. use of ''Zea mays'' L. at Cubilán area, highland Ecuador, revealed by ancient starches |journal=[[Quaternary International]]|date=June 2016 |volume=404 |pages=137–155 |doi=10.1016/j.quaint.2015.08.025 |bibcode=2016QuInt.404..137P }}</ref>

According to a genetic study by the [[Brazilian Agricultural Research Corporation]] (Embrapa), corn cultivation was introduced in South America from Mexico, in two great waves: the first, more than 6000 years ago, spread through the [[Andes]]. Evidence of cultivation in Peru has been found dating to about 6700 years ago.<ref name="BBC Mundo">{{cite web |title=Los antiguos peruanos comían palomitas de maíz |website=BBC Mundo |publisher=BBC |date=19 January 2012 |url=http://www.bbc.com/mundo/noticias/2012/01/120118_peru_maiz_antiguedad_jgc.shtml}}</ref> The second wave, about 2000 years ago, through the lowlands of South America.<ref>{{cite web|url=https://www.yumpu.com/pt/document/view/36138294/o-homem-seguiu-as-plantas-ou-as-plantas-seguiram-o-homem/9|title=Did man follow plants or did plants follow man? Tracks of prehistoric man and ways of contact in the Americas according to cultivated plants. Case study – Maize (translated from Portuguese)|date=2015|publisher=Yumpu|access-date=October 13, 2015}}</ref>

The earliest maize plants grew only small, {{convert|25|mm|in|0|adj=mid|-long}} corn ears, and only one per plant. In Jackson Spielvogel's view, many centuries of artificial selection (rather than the current view that maize was exploited by interplanting with ''[[teosinte]]'') by the indigenous people of the Americas resulted in the development of maize plants capable of growing several ears per plant, which were usually several centimetres/inches long each.<ref name="Spielvogel2005">{{cite book|first=Jackson J. |last=Spielvogel|title=Medieval and Early Modern Times: Discovering Our Past|url={{google books |plainurl=y |id=UbbIAAAACAAJ}}|date=1 March 2005|publisher=Glencoe/McGraw-Hill School Publishing Company|isbn=978-0-07-868876-8}}</ref> The [[Olmec]] and [[Maya peoples|Maya]] cultivated maize in numerous varieties throughout [[Mesoamerica]]; they cooked, ground and processed it through [[nixtamalization]]. It was believed that beginning about 2500 BC, the crop spread through much of the Americas.<ref name="archsouth">{{cite journal|last=Roney|first=John|title=The Beginnings of Maize Agriculture|journal=[[Archaeology Southwest]]|volume=23|issue=1|date=Winter 2009|page=4}}</ref> Research of the 21st century has established even earlier dates. The region developed a trade network based on surplus and varieties of maize crops.{{Citation needed|date=January 2021}}

[[Mapuche]]s of [[Zona Sur|south-central Chile]] cultivated maize along with [[quinoa]] and [[potatoes]] in [[Pre-Columbian era|pre-Hispanic]] times; however, potato was the [[staple food]] of most Mapuches, "specially in the southern and coastal [Mapuche] territories where maize did not reach maturity".<ref name=BengoaAntiguo199-200>{{cite book |last=Bengoa |first=José |author-link=José Bengoa|title=Historia de los antiguos mapuches del sur |year=2003 |publisher=[[Catalonia (publisher)|Catalonia]] |location=Santiago |isbn=956-8303-02-2 |language=es|pages=199–200}}</ref><ref name=Dille2007>{{cite journal |last1=Dillehay |first1=Tom D. |author-link=Tom Dillehay |author-link2=Mario Pino Quivira |last2=Pino Quivira |first2=Mario |last3=Bonzani |first3=Renée |last4=Silva |first4=Claudia |last5=Wallner |first5=Johannes |last6=Le Quesne |first6=Carlos |year=2007 |title=Cultivated wetlands and emerging complexity in south-central Chile and long distance effects of climate change |url=http://www.dendrocronologia.cl/pubs/2007_Dillehay(AncientCultivatedWetlands).pdf |journal=[[Antiquity (journal)|Antiquity]] |volume=81 |issue=314 |pages=949–960 |doi=10.1017/s0003598x00096034 |s2cid=59480757 }}</ref> Before the expansion of the [[Inca Empire]] maize was traded and transported as far south as 40°19' S in Melinquina, [[Lácar Department]].<ref name=PerezErre2011>{{cite journal |last1=Pérez |first1=Alberto E. |last2=Erra |first2=Georgina |date=2011 |title=Identificación de maiz de vasijas recuperadas de la Patagonia noroccidental argentina.|trans-title=Identifying maize residues in pottery vessels in northwestern Patagonia, Argentina|language=es |journal=[[Magallania]] |volume=39 |issue=2 |pages=309–316 |doi=10.4067/S0718-22442011000200022 |doi-access=free}}</ref> In that location maize remains were found inside pottery dated to 730&nbsp;±&nbsp;80&nbsp;BP and 920&nbsp;±&nbsp;60&nbsp;BP. Probably this maize was brought across the Andes from Chile.<ref name=PerezErre2011/> The presence of maize in [[Guaitecas Archipelago]] (43°55' S), the southernmost outpost of pre-Hispanic agriculture,<ref>{{cite book |last=Bird |first=Junius |date=1946|chapter=The Alacaluf |title=Handbook of South American Indians|editor-last=Steward|editor-first=Julian H. |publisher=–Bureau of American Ethnology|series=Bulletin 143 |volume=I |pages=55–79 }}</ref> is reported by early Spanish explorers.<ref name=Torrejon/> However the Spanish may have misidentified the plant.<ref name=Torrejon>{{cite journal |last1=Torrejón |first1=Fernando |last2=Bizama |first2=Fernando |last3=Araneda |first3=Alberto |last4=Aguayo |first4=Mauricio|last5=Bertrand |first5=Sébastien|last6=Urrutia |first6=Roberto |date=2013 |title=Descifrando la historia ambiental de los archipiélagos de Aysén, Chile: El influjo colonial y la explotación económica-mercantil republicana (siglos XVI-XIX) |trans-title=Deciphering the environmental history of the Aysén archipelagos, Chile: Colonial influence and commercial exploitation during the Republican Era (XVI-XIX centuries)|journal=[[Magallania]] |volume=41 |issue=1 |pages=29–52|language=es |doi=10.4067/S0718-22442013000100002 |doi-access=free}}</ref>

By at least 1000 BCE, the [[Olmec]] in [[Mesoamerica]] had based their calendar, language, myths and worldview with maize at the center of their symbolism.<ref name=Fussell1999/>

=== Columbian exchange ===
After the arrival of Europeans in 1492, Spanish settlers consumed maize, and explorers and traders [[Columbian Exchange|carried it back to Europe]] and introduced it to other countries. Spanish settlers much preferred [[wheat]] bread to maize, [[cassava]], or [[potatoes]]. Maize flour could not be substituted for wheat for communion bread, since in [[Christianity|Christian]] belief only wheat could undergo [[transubstantiation]] and be transformed into the body of Christ.<ref>[[Rebecca Earle]], ''The Body of the Conquistador: Food, Race, and the Colonial Experience in Spanish America, 1492–1700''. New York: Cambridge University Press 2012, pp. 17, 151.</ref> Some Spaniards worried that by eating indigenous foods, which they did not consider nutritious, they would weaken and risk turning into Indians. "In the view of Europeans, it was the food they ate, even more than the environment in which they lived, that gave Amerindians and Spaniards both their distinctive physical characteristics and their characteristic personalities."<ref>Earle, ''The Body of the Conquistador'', p. 5.</ref> Despite these worries, Spaniards did consume maize. [[Archaeological record|Archeological evidence]] from Florida sites indicate they cultivated it as well.<ref name="auto">Earle, ''The Body of the Conquistador'', p. 144.</ref>

Maize spread to the rest of the world because of its ability to grow in diverse climates. It was cultivated in Spain just a few decades after Columbus's voyages and then spread to Italy, West Africa and elsewhere.<ref name="auto" />
Widespread cultivation most likely began in southern Spain in 1525, after which it quickly spread to the rest of the [[Spanish Empire]] including its territories in Italy (and, from there, to other Italian states). Maize had many advantages over wheat and barley; it yielded two and a half times the [[food energy]] per unit cultivated area,<ref>Marion Eugene Ensminger and Audrey H. Ensminger. "Foods & Nutrition Encyclopedia, Two Volume Set." CRC-Press: 1994. Page 1104.</ref> could be harvested in successive years from the same plot of land, and grew in wildly varying altitudes and climates, from relatively dry regions with only {{cvt|10|in|mm|order=flip|-1}} of annual rainfall to damp regions with over {{cvt|200|in|mm|sigfig=1|order=flip}}. By the 17th century it was a common peasant food in Southwestern Europe, including Portugal, Spain, southern France, and Italy. By the 18th century, it was the chief food of the southern French and Italian peasantry, especially in the form of [[polenta]] in Italy.<ref>William L. Langer, "American Foods and Europe's Population Growth 1750–1850", [[Journal of Social History]], 8#2 (1975), pp. 51–66. Pages 58–60.</ref>

== Names ==
[[File:Corntassel 7095.jpg|thumb|upright|Many small male flowers make up the male inflorescence, called the tassel.]]

The word ''maize'' derives from the Spanish form of the indigenous [[Taíno people|Taíno]] word for the plant, ''mahiz''.<ref>{{OED|maize, n. (and adj.)}}</ref> Linnaeus included the common name maize as the species epithet in ''Zea mays''.<ref name="Ranum">{{cite journal |last1=Ranum |first1=Peter |last2=Peña-Rosas |first2=Juan Pablo |last3=Garcia-Casal |first3=Maria Nieves |title=Global maize production, utilization, and consumption |journal=[[Annals of the New York Academy of Sciences]] |date=April 2014 |volume=1312 |issue=1 |pages=105–112 |doi=10.1111/nyas.12396|pmid=24650320 |bibcode=2014NYASA1312..105R |s2cid=4640742 |doi-access=free }}</ref> It is known by other names including "corn" in some English speaking countries.<ref>{{Cite book|last=Head|first=John W.|url=https://books.google.com/books?id=XMiVDQAAQBAJ&pg=PT52|title=International Law and Agroecological Husbandry: Building legal foundations for a new agriculture|date=2016-11-25|publisher=Routledge|isbn=978-1-315-44650-9|language=en}}</ref>

''Maize'' is preferred in formal, scientific, and international usage as a [[common name]] because it refers specifically to this one grain, unlike ''corn'', which has a complex variety of meanings that vary by context and geographic region.<ref name="Ensminger">{{cite book |title=Foods and Nutrition Encyclopedia, 2nd ed. |publisher=CRC Press |last=Ensminger |first=Audrey H. |year=1994 |isbn=978-0-8493-8980-1 |page=[{{google books |plainurl=y |id=XMA9gYIj-C4C|page=479}} 479] |quote=The word "maize" is preferred in international usage because in many countries the term "corn", the name by which the plant is known in the United States, is synonymous with the leading cereal grain; thus, in England "corn" refers to wheat, and in Scotland and Ireland it refers to oats.}}</ref> The US and a handful of other English-speaking countries primarily use corn, though most countries use the term maize.<ref>{{cite web |last1=Espinoza |first1=Mauricio |title='All Corn Is the Same,' and Other Foolishness about America's King of Crops |url=https://cfaes.osu.edu/news/articles/%E2%80%98all-corn-is-the-same%E2%80%99-and-other-foolishness-about-america%E2%80%99s-king-crops |publisher=Ohio State University: College of Food, Agricultural, and Environmental Sciences |access-date=21 September 2022 |language=en}}</ref><ref name="OxfordEncyclopedia"/><ref>{{cite web |title=Grain |url=https://education.nationalgeographic.org/resource/grain/ |website=education.nationalgeographic.org |publisher=National Geographic |access-date=27 February 2023 |language=en|quote=In most countries, the grain of the ''Zea mays'' plant is called maize. In the United States, it's called corn.}}</ref> The word maize is considered interchangeable in place of corn in [[Western world|the West]]; during early British and American trade, all grains were considered corn. Maize retained the name corn in the West as the primary grain in these trade relationships.<ref name="Ranum"/>

The word "corn" outside the US, Canada, Australia, and New Zealand is synonymous with [[grain]] referring to any [[cereal]] crop with its meaning understood to vary geographically to refer to the local [[staple food|staple]],<ref name=OED_corn /> such as wheat in England and oats in Scotland or Ireland.<ref name="Ensminger"/> In the United States,<ref name=OED_corn /> Canada,<ref>{{cite book |url={{google books |plainurl=y |id=uW2rM_6I3gMC|page=109}} |title=The English Language in Canada: Status, History and Comparative Analysis |publisher=[[Cambridge University Press]] (CUP)|author=Boberg, Charles |year=2010 |page=109 |isbn=978-1-139-49144-0}}</ref> Australia, and New Zealand, ''corn'' primarily means maize. This usage started as a shortening of "Indian corn" in 18th century North America.<ref name=OED_corn>{{OED|corn, n.1}}</ref><ref name="Mencken">{{cite book |last1=Mencken |first1=H. L. |title=The American language : an inquiry into the development of English in the United States |date=1984 |publisher=[[Alfred A. Knopf]]|location=New York |isbn=0394400755 |page=122 |edition=4th, corrected, enl., and rewritten|quote=Corn, in orthodox English, means grain for human consumption, especially wheat, e.g., the Corn Laws. The earliest settlers, following this usage, gave the name of Indian corn to what the Spaniards, following the Indians themselves, had called maiz. . . . But gradually the adjective fell off, and by the middle of the Eighteenth Century maize was simply called corn and grains in general were called breadstuffs. Thomas Hutchinson, discoursing to George III in 1774, used corn in this restricted sense speaking of "rye and corn mixed." "What corn?" asked George. "Indian corn," explained Hutchinson, "or as it is called in authors, maize."}}</ref> During European colonization of North America, confusion would occur between British and North American English speakers using the term corn so that North American speakers would need to clarify that they were talking about Indian corn or maize, such as in a conversation between the [[Province of Massachusetts Bay|Massachusetts Bay]] governor [[Thomas_Hutchinson_(governor)|Thomas Hutchinson]] and the British king [[George III]].<ref name="Mencken"/> "Indian corn" primarily means maize (the staple grain of [[Indigenous peoples of the Americas|indigenous Americans]]) but can also refer more specifically to multicolored "[[flint corn]]" used for decoration.<ref>[http://www.merriam-webster.com/dictionary/indian_corn "Indian corn"], [[Merriam-Webster]] Dictionary, definition 3, accessed June 7, 2012</ref> Other common names include barajovar, makka, silk maize, and zea.<ref>{{cite journal |last1=Rouf Shah |first1=Tajamul |last2=Prasad |first2=Kamlesh |last3=Kumar |first3=Pradyuman |title=Maize - A potential source of human nutrition and health: A review |journal=[[Cogent Food & Agriculture]] |date=4 April 2016 |volume=2 |issue=1 |doi=10.1080/23311932.2016.1166995|s2cid=87844060 |doi-access=free }}</ref>

Betty Fussell writes in an article on the history of the word "corn" in North  America that "[t]o say the word "corn" is to plunge into the tragi-farcical mistranslations of language and history".<ref name=Fussell1999>{{cite journal |last1=Fussell |first1=Betty |title=Translating Maize into Corn: The Transformation of America's Native Grain |journal=Social Research |date=1999 |volume=66 |issue=1 |pages=41–65 |id={{Gale|A54668866}} {{ProQuest|209670587}} |jstor=40971301|quote=To say the word "corn" is to plunge into the tragi-farcical mistranslations of language and history. If only the British had followed Columbus in phoneticizing the Taino word mahiz, which the Arawaks named their staple grain, we wouldn't be in the same linguistic pickle we're in today, where I have to explain to someone every year that when Biblical Ruth "stood in tears amid the alien corn" she was standing in a wheat field. But it was a near thing even with the Spaniards, when we read in Columbus' Journals that the grain "which the Indians called maiz... the Spanish called panizo.' The Spanish term was generic for the cereal grains they knew - wheat, millet, barley, oats - as was the Italian term polenta, from Latin pub. As was the English term "corn," which covered grains of all kinds, including grains of salt, as in "corned beef. <br /> French linguistic imperialism, by way of a Parisian botanist in 1536, provided the term Turcicum frumentum, which the British quickly translated into "Turkey wheat," "Turkey corn," and "Indian corn." By Turkey or Indian, they meant not a place but a condition, a savage rather than a civilized grain, with which the Turks concurred, calling it kukuruz, meaning barbaric. }}</ref> Similar to the British, the Spanish referred to maize as panizo, a generic term for cereal grains, as did Italians with the term polenta. The British later referred to maize as Turkey wheat, Turkey corn, or Indian corn with Fusell commenting that "they meant not a place but a condition, a savage rather than a civilized grain", especially with [[Turkish people]] later naming it kukuruz, or barbaric.<ref name=Fussell1999/>

International groups such as the [[Centre for Agriculture and Bioscience International]] also consider maize the preferred common name.<ref>{{cite web |title=''Zea mays'' (maize) |url=https://www.cabi.org/isc/datasheet/57417 |publisher=CABI |access-date=16 September 2022}}</ref> The word ''maize'' is used by agricultural bodies and [[research institute]]s such as the UN's [[FAO]],<ref>{{cite web |title=Maize |url=https://www.fao.org/land-water/databases-and-software/crop-information/maize/en/ |publisher=FAO |access-date=16 September 2022}}</ref> the [[International Maize and Wheat Improvement Center]] based out of Mexico, and the Indian Institute of Maize Research.<ref>{{cite web |title=Overview – ICAR-Indian Institute of Maize Research |url=https://iimr.icar.gov.in/overview/ |access-date=16 September 2022}}</ref> National agricultural and industry associations often include the word ''maize'' in their name such as the Maize Association of Australia,<ref>{{cite web |title=Maize Association - Maize Association Australia |url=https://www.maizeaustralia.com.au/ |access-date=16 September 2022}}</ref> and the National Maize Association of Nigeria.<ref>{{cite web |title=The Maize Association of Nigeria honors IITA for supporting the nation's agriculture |url=https://www.iita.org/news-item/the-maize-association-of-nigeria-honors-iita-for-supporting-the-nations-agriculture/ |publisher=International Institute of Tropical Agriculture |access-date=16 September 2022}}</ref>

In Southern Africa, maize is commonly called ''mielie'' ([[Afrikaans]]) or ''mealie'' (English), words possibly derived from the Portuguese word for maize, ''milho'', but more probably from Dutch ''meel'' or English ''meal'', meaning the edible part of a grain or [[Legume|pulse]].<ref name=OED_mealie>{{OED|mealie, n.}}</ref>

== Structure and physiology ==
The maize plant is often {{convert|3|m|ft|abbr=on|0}} in height,<ref name="Races of Maize in Mexico">{{cite book|url={{google books |plainurl=y |id=tXxQAAAAMAAJ}} |title=Races of Maize in Mexico|last1=Wellhausen|first1=Edwin John|year=1952}}</ref> though some natural strains can grow {{convert|13|m|ft|abbr=on|0}},<ref>{{cite journal|url=https://mnl.maizegdb.org/86/pdf/33karl.pdf|page=4|title=The Maximum Leaf Number of the Maize Subspecies|issn=1090-4573|volume=86|journal=The Maize Genetics Cooperation Newsletter|date=January 2012|first=J.R.|last=Karl|access-date=July 5, 2013|archive-url=https://web.archive.org/web/20160303220512/http://www.agron.missouri.edu/mnl/86/MNL86.pdf|archive-date=March 3, 2016|url-status=dead|df=mdy-all}}</ref> and the tallest recorded plant reached almost {{convert|14|m|ft}}.<ref>{{Cite web|date=2017-01-06|title=World's tallest corn towers nearly 14 meters|url=https://www.sciencenewsforstudents.org/article/worlds-tallest-corn-towers-nearly-14-meters|access-date=2021-11-10|website=Science News for Students|language=en-US}}</ref> The stem is commonly composed of 20 [[internode (botany)|internodes]]<ref>{{cite journal |last1=Stevenson |first1=J. C. |last2=Goodman |first2=M. M. |title=Ecology of Exotic Races of Maize. I. Leaf Number and Tillering of 16 Races Under Four Temperatures and Two Photoperiods 1 |journal=Crop Science |date=November 1972 |volume=12 |issue=6 |pages=864–868 |doi=10.2135/cropsci1972.0011183X001200060045x }}</ref> of {{convert|18|cm|in|frac=2|abbr=on}} length.<ref name="Races of Maize in Mexico" /> The leaves arise from the nodes, alternately on opposite sides on the stalk,<ref>{{cite book
 | title= Soils, Plant Growth and Crop Production Volume II
 | chapter= Growth And Production Of Maize: Traditional Low-Input Cultivation
 | editor=Willy H. Verheye
 | date=2010
 | publisher=[[EOLSS]] Publishers
 | isbn=978-1-84826-368-0
 | url=https://www.eolss.net/ebooklib/bookinfo/soils-plant-growth-crop-production.aspx
 | page=74
 }}</ref> and have [[Glossary of botanical terms|entire margin]]s.<ref>{{Cite book|last1=Assefa|first1=Yared|url=https://books.google.com/books?id=N3spAgAAQBAJ&pg=PA8|title=Corn and Grain Sorghum Comparison: All Things Considered|last2=Roozeboom|first2=Kraig|last3=Thompson|first3=Curtis|last4=Schlegel|first4=Alan|last5=Stone|first5=Loyd|last6=Lingenfelser|first6=Jane|date=2013-12-16|publisher=Academic Press|isbn=978-0-12-800395-4|language=en}}</ref>

The apex of the stem ends in the tassel, an [[inflorescence]] of male flowers; these are separate from the female flowers but borne on the same plant ([[monoecy]]). When the tassel is mature and conditions are suitably warm and dry, anthers on the tassel [[dehiscence (botany)|dehisce]] and release pollen. Maize pollen is [[Anemophily|anemophilous]] (dispersed by wind), and because of its large settling velocity, most pollen falls within a few meters of the tassel.<ref>{{cite journal |last1=Oldenburg |first1=Marcus |last2=Petersen |first2=Arnd |last3=Baur |first3=Xaver |title=Maize pollen is an important allergen in occupationally exposed workers |journal=Journal of Occupational Medicine and Toxicology |date=2011 |volume=6 |issue=1 |pages=32 |doi=10.1186/1745-6673-6-32 |pmc=3269392 |pmid=22165847 |doi-access=free }}</ref>

Ears develop above a few of the leaves in the midsection of the plant, between the stem and leaf sheath, elongating by around {{convert|3|mm|in|frac=32|abbr=on}} per day, to a length of {{convert|18|cm|in|frac=2|abbr=on}}<ref name="Races of Maize in Mexico" /> with {{convert|60|cm|in|abbr=on|0}} being the maximum alleged in the subspecies.<ref>{{cite journal|url=http://www.agron.missouri.edu/mnl/89/pdf/03karl.pdf|title=Jala Maize is Small|journal=[[Maize Genetics MNL]]|year=2007|volume=89|pages=e3|first=J. R.|last=Karl|access-date=November 19, 2015|archive-url=https://web.archive.org/web/20170808191736/http://www.agron.missouri.edu/mnl/89/pdf/03karl.pdf|archive-date=August 8, 2017|url-status=dead|df=mdy-all}}</ref> They are female [[inflorescence]]s, tightly enveloped by several layers of ear leaves commonly called husks.

Elongated [[Stigma (botany)|stigmas]], called [[corn silk|silks]], emerge from the whorl of husk leaves at the end of the ear. They are often pale yellow and {{convert|18|cm|in|frac=2|abbr=on}} in length, like tufts of hair in appearance. At the end of each is a carpel, which may develop into a "kernel" if fertilized by a pollen grain. The [[pericarp]] of the fruit is fused with the seed coat referred to as "[[caryopsis]]", typical of the [[Poaceae|grasses]], and the entire kernel is often referred to as the "[[seed]]". The cob is close to a [[multiple fruit]] in structure, except that the individual fruits (the kernels) never fuse into a single mass. The grains are about the size of [[pea]]s, and adhere in regular rows around a white, pithy substance, which forms the cob. The maximum size of kernels is reputedly {{convert|2.5|cm|in|abbr=on|0}}.<ref>{{cite book|url={{google books |plainurl=y |id=dD4rAAAAYAAJ}}|title=Races of Maize in Peru|last1=Grobman|first1=Alexander|year=1961}}</ref> An ear commonly holds 600 kernels. They are of various colors: blackish, [[blue corn|bluish-gray]], [[purple corn|purple]], green, red, white and yellow. When ground into [[flour]], maize yields more flour with much less [[bran]] than wheat does. It lacks the protein [[gluten]] of wheat and, therefore, makes baked goods with poor rising capability. A [[mutation|genetic variant]] that accumulates more sugar and less [[starch]] in the ear is consumed as a vegetable and is called [[sweet corn]]. Young ears can be consumed raw, with the [[corncob|cob]] and silk, but as the plant matures (usually during the summer months), the cob becomes tougher and the silk dries to inedibility. By the end of the [[growing season]], the kernels dry out and become difficult to chew without cooking.<ref>{{Cite book|last1=Solaimalai|first1=A.|url=https://books.google.com/books?id=T7XjDwAAQBAJ&pg=PT60|title=Maize Crop: Improvement, Production, Protection and Post Harvest Technology|last2=Anantharaju|first2=P.|last3=Irulandi|first3=S.|last4=Theradimani|first4=M.|date=2020-05-10|publisher=CRC Press|isbn=978-1-000-17695-7|language=en}}</ref>
<gallery mode="packed">
File:Cornsilk 7091.jpg|Female inflorescence, with young [[corn silk|silk]]
File:Corn blooming.jpg|Mature silk
File:GreenCorn.JPG|Stalks, ears and silk
File:Männliche Blüte einer Maispflanze 2009-08-19.JPG|Male flowers
File:ZeaMays.jpg|Full-grown maize plants
File:Klip kukuruza uzgojen u Međimurju (Croatia).JPG|Mature maize ear on a stalk
</gallery>

[[File:Maize plant diagram.svg|thumb|upright|Maize plant diagram]]
Planting density affects multiple aspects of maize. Modern farming techniques in [[Developed country|developed countries]] usually rely on dense planting, which produces one ear per stalk.<ref>[http://www.agronext.iastate.edu/corn/corn-qna.html Common Corn Questions and Answers] {{webarchive|url=https://web.archive.org/web/20120501194103/http://www.agronext.iastate.edu/corn/corn-qna.html |date=May 1, 2012}}, Iowa State University of Science and Technology, Agronomy Extension, 2011</ref> Stands of [[silage]] maize are yet denser,{{citation needed|date=November 2019}} and achieve a lower percentage of ears and more plant matter.{{Citation needed|date=January 2021}}

Maize is a [[Long-night plant|facultative short-day plant]]<ref>{{cite journal|url=https://mnl.maizegdb.org/89/pdf/07karl.pdf|page=e7|title=Maize is Not Day Neutral; Day Length and Flowering|volume=89|journal=The Maize Genetics Cooperation Newsletter|date=January 2002|first=J.R.|last=Karl|access-date=September 6, 2015|archive-url=https://web.archive.org/web/20170808190604/http://www.agron.missouri.edu/mnl/89/pdf/07karl.pdf|archive-date=August 8, 2017|url-status=dead|df=mdy-all}}</ref> and flowers in a certain number of [[growing degree day]]s <nowiki>></nowiki> {{convert|10|°C|°F|abbr=on}} in the environment to which it is adapted.<ref>{{cite book|url={{google books |plainurl=y |id=x-bwAAAAMAAJ}} |title=Tropical maize: Improvement and production |isbn=9789251044575 |last1=Paliwal |first1=R. L |year=2000|publisher=Food and Agricultural Organization of the United Nations }}</ref> The magnitude of the influence that long nights have on the number of days that must pass before maize [[flower]]s is genetically prescribed<ref>{{cite web|url=http://www.eurekalert.org/pub_releases/2011-06/asoa-ugc061411.php |title=Unique gene combinations control tropical maize response to day lengths |publisher=Eurekalert.org |date=June 14, 2011 |access-date=November 14, 2013}}</ref> and regulated by the [[phytochrome]] system.<ref>{{cite web|url=http://www.brutnelllab.org/node/32 |title=Elongated mesocotyl1, a phytochrome-deficient mutant of maize. |publisher=Brutnell Lab |access-date=December 7, 2013 |url-status=dead |archive-url=https://web.archive.org/web/20131211111733/http://www.brutnelllab.org/node/32 |archive-date=December 11, 2013 }}</ref> [[circadian rhythm|Photoperiodicity]] can be eccentric in tropical [[cultivar]]s such that the long days characteristic of higher latitudes allow the plants to grow so tall that they do not have enough time to produce seed before being killed by frost. These attributes, however, may prove useful in using tropical maize for [[biofuel]]s.<ref>{{Cite web|url=https://aces.illinois.edu/news|title=News|website=College of Agricultural, Consumer & Environmental Sciences}}</ref>

Immature maize shoots accumulate a powerful antibiotic substance, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one ([[DIMBOA]]). DIMBOA is a member of a group of [[hydroxamic acid]]s (also known as benzoxazinoids) that serve as a natural defense against a wide range of pests, including insects, [[pathogenic]] fungi and [[bacteria]]. DIMBOA is also found in related grasses, particularly wheat. A maize mutant (bx) lacking DIMBOA is highly susceptible to attack by [[aphid]]s and [[fungi]]. DIMBOA is also responsible for the relative resistance of immature maize to the [[European corn borer]] (family [[Crambidae]]). As maize matures, DIMBOA levels and resistance to the corn borer decline.{{Citation needed|date=January 2021}}

Because of its shallow roots, maize is susceptible to droughts, intolerant of nutrient-deficient soils, and prone to be uprooted by severe winds.<ref>{{cite web|title=Corn Stalk Lodging |publisher=[[Monsanto Company|Monsanto]] Imagine |date=October 2, 2008 |url=http://www.dekalb.ca/content/pdf/corn_stalk_lodging.pdf |access-date=February 23, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090225054032/http://www.dekalb.ca/content/pdf/corn_stalk_lodging.pdf |archive-date=February 25, 2009 }}</ref>

<gallery mode="packed">
File:Ab food 06.jpg|Maize kernels
File:Aa maize ear irregular 01.jpg|Ear of maize with irregular rows of kernels
</gallery>

While yellow maizes derive their color from [[lutein]] and [[zeaxanthin]], in red-colored maizes, the kernel coloration is due to [[anthocyanin]]s and [[phlobaphene]]s. These latter substances are synthesized in the flavonoids synthetic pathway<ref>{{cite journal|pmid=12096095|year=2002|last1=Himi|first1=E|last2=Mares|first2=DJ|last3=Yanagisawa |first3=A|last4=Noda|first4=K|title=Effect of grain color gene (R) on grain dormancy and sensitivity of the embryo to abscisic acid (ABA) in wheat|volume=53|issue=374|pages=1569–74|journal=[[Journal of Experimental Botany]]|doi=10.1093/jxb/erf005|doi-access=free}}</ref> from polymerization of [[flavan-4-ol]]s<ref>{{cite journal|pmid=11402179|year=2001|last1=Winkel-Shirley|first1=B|title=Flavonoid biosynthesis. A colorful model for genetics, biochemistry, cell biology, and biotechnology|volume=126|issue=2|pages=485–93|pmc=1540115|journal=[[Plant Physiology]]|doi=10.1104/pp.126.2.485}}</ref> by the expression of maize pericarp color1 (p1) gene<ref name=Chopra2003>{{cite journal |pmc=1462483 |year=2003 |last1=Chopra |first1=S |last2=Cocciolone |first2=SM |last3=Bushman |first3=S |last4=Sangar |first4=V |last5=McMullen|first5=MD|last6=Peterson|first6=T|title=The maize unstable factor for orange1 is a dominant epigenetic modifier of a tissue specifically silent allele of pericarp color1|volume=163|issue=3|pages=1135–1146|journal=[[Genetics (journal)|Genetics]]|doi=10.1093/genetics/163.3.1135 |pmid=12663550}}</ref> which encodes an R2R3 [[MYB (gene)|myb]]-like [[transcriptional activator]]<ref>[http://www.intl-pag.org/16/abstracts/PAG16_P05d_343.html Structural And Transcriptional Analysis Of The Complex P1-wr Cluster In Maize. Wolfgang Goettel, Joachim Messing. Plant & Animal Genomes XVI Conference] {{webarchive|url=https://web.archive.org/web/20120218100748/http://www.intl-pag.org/16/abstracts/PAG16_P05d_343.html |date=February 18, 2012}}</ref> of the A1 gene encoding for the [[dihydroflavonol 4-reductase]] (reducing [[dihydroflavonol]]s into flavan-4-ols)<ref>{{cite journal|pmid=11553733|year=2001|last1=Dong|first1=X|last2=Braun|first2=EL|last3=Grotewold|first3=E|title=Functional conservation of plant secondary metabolic enzymes revealed by complementation of Arabidopsis flavonoid mutants with maize genes|volume=127|issue=1|pages=46–57|pmc=117961|journal=[[Plant Physiology]]|doi=10.1104/pp.127.1.46}}</ref> while another gene (Suppressor of Pericarp Pigmentation 1 or SPP1) acts as a [[transcriptional suppressor|suppressor]].<ref>{{cite journal|title=Suppressor of Pericarp Pigmentation 1 (SPP1), a novel gene involved in phlobaphene accumulation in maize (''Zea mays'' L.) pericarps|last1=Lee|first1=E.A. |last2=Harper|first2=V|journal=[[Maydica]]|year=2002 |volume=47 |pages=51–58|id={{INIST|13772300}} |issue=1}}</ref> The p1 gene encodes an Myb-homologous transcriptional activator of genes required for biosynthesis of red phlobaphene pigments, while the P1-wr allele specifies colorless kernel pericarp and red cobs, and unstable factor for orange1 (Ufo1) modifies P1-wr expression to confer pigmentation in kernel pericarp, as well as vegetative tissues, which normally do not accumulate significant amounts of phlobaphene pigments.<ref name=Chopra2003 /> The maize P gene encodes a Myb homolog that recognizes the sequence CCT/AACC, in sharp contrast with the C/TAACGG bound by vertebrate Myb proteins.<ref>{{cite journal|doi=10.1016/0092-8674(94)90117-1|title=The myb-homologous P gene controls phlobaphene pigmentation in maize floral organs by directly activating a flavonoid biosynthetic gene subset|year=1994|last1=Grotewold|first1=Erich|last2=Drummond|first2=Bruce J. |last3=Bowen|first3=Ben|last4=Peterson |first4=Thomas|journal=[[Cell (journal)|Cell]]|volume=76|issue=3|pages=543–53|pmid=8313474|s2cid=42197232}}</ref>

{{anchor|Ear leaf}}The ''ear leaf'' is the leaf most closely associated with a particular developing ear. This leaf and above contribute 70%<ref name="gray-leaf-spot-CropWatch">{{cite web |title=Gray Leaf Spot Severity Increasing Rapidly |website=[[CropWatch]] |date=2015-09-17 |url=http://cropwatch.unl.edu/gray-leaf-spot-severity-increasing-rapidly |access-date=2021-07-24}}</ref> to 75% to 90%<ref name="USA-IA-ext-fung">{{cite web |title=Before applying fungicides to corn: Stop! Look! Consider! |website=Integrated Crop Management |publisher=[[Iowa State University Extension]] |url=http://crops.extension.iastate.edu/encyclopedia/applying-fungicides-corn-stop-look-consider |access-date=2021-07-24}}</ref> of [[grain fill]]. Therefore [[fungicide]] application is most important in that region in most disease environments.<ref name="gray-leaf-spot-CropWatch" /><ref name="USA-IA-ext-fung" />

<gallery mode=packed>
File:Zea mays 'Ottofile giallo Tortonese' MHNT.BOT.2015.34.1.jpg|[[cultivar|cv.]] 'Ottofile giallo Tortonese{{`}}' – [[MHNT]]
File:Zea mays fraise MHNT.BOT.2011.18.21.jpg|cv. "strawberry"—[[MHNT]]
File:Dent Corn 'Oaxacan Green' (Zea mays) MHNT 2.jpg|cv. "Oaxacan Green" [[MHNT]]
File:Corncobs.jpg|Variegated maize ears
File:CSIRO ScienceImage 3195 Maize or corn.jpg|Multicolored corn kernels ([[CSIRO]])
</gallery>

=== Abnormal flowers ===
Maize flowers may sometimes exhibit mutations that lead to the formation of female flowers in the tassel. These mutations, ''ts4'' and ''Ts6'', prohibit the development of the stamen while simultaneously promoting pistil development.<ref>{{Cite journal|last=Irisch|first=Erin E.|year=1997|doi=10.2307/2446611|journal=[[American Journal of Botany]]|volume=84 |issue=11 |pages=1502–1515|jstor=2446611|title=Class II tassel seed mutations provide evidence for multiple types of inflorescence meristems in maize (Poaceae)|pmid=21708555}}</ref> This may cause [[inflorescence]]s containing both male and female flowers, or [[hermaphrodite]] flowers.<ref>{{cite journal|url=https://en.wikisource.org/wiki/Popular_Science_Monthly/Volume_68/January_1906/What_Is_an_Ear_of_Corn?|journal=[[Popular Science Monthly]]|volume=68|issue=January|year=1906|title=What is an ear of corn?|author=Montgomery E}}</ref>

{{ Anchor | Genomics | Genetics }}
== Genomics and genetics ==
[[File:GEM corn.jpg|thumb|right|Exotic varieties are collected to add [[genetic diversity]] when [[crop breeding|selectively breeding]] new domestic [[strain (biology)|strain]]s]]
[[File:Corn with white and yellow kernels.jpg|thumb|With white and yellow kernels]]
Maize is an annual grass in the family [[Gramineae]], which includes such plants as [[wheat]], [[rye]], [[barley]], [[rice]], [[sorghum]], and [[sugarcane]]. There are two major species of the genus ''[[Zea (plant)|Zea]]'' (out of six total): ''Z. mays'' (maize) and ''[[Zea diploperennis|Z. diploperennis]]'', which is a [[Perennial plant|perennial]] type of teosinte. The [[Annual plant|annual]] teosinte variety called ''[[Zea mays mexicana|Z. m. mexicana]]'' is the closest botanical relative to maize. It still grows in the wild as an annual in Mexico and Guatemala.<ref name=oup>{{Cite book |title=Corn|publisher=[[Oxford Reference]]|access-date=2017-12-04 |url=http://www.oxfordreference.com/view/10.1093/acref/9780199734962.001.0001/acref-9780199734962-e-0218 |doi=10.1093/acref/9780199734962.001.0001 |isbn=9780199734962 |year=2012 |last1=Kraig |first1=Bruce}}</ref>

Many forms of maize are used for food, sometimes classified as various subspecies related to the amount of starch each has:
* Flour corn: ''Z. m.'' var. ''amylacea''
* [[Popcorn]]: ''Z. m.'' var. ''everta''
* [[Dent corn]] : ''Z. m.'' var. ''indentata''
* [[Flint corn]]: ''Z. m.'' var. ''indurata''
* [[Sweet corn]]: ''Z. m.'' var. ''saccharata'' and ''Z. m.'' var. ''rugosa''
* [[Waxy corn]]: ''Z. m.'' var. ''ceratina''
* [[Amylomaize]]: ''Z. mays''{{ Verification needed | date=November 2022 }}
* [[Pod corn]]: ''Z. m.'' var. ''tunicata'' Larrañaga ex A. St. Hil.
* [[Striped maize]]: ''Z. m.'' var. ''japonica''

This system has been replaced (though not entirely displaced) over the last 60 years by multivariable classifications based on ever more data. [[Agronomics|Agronomic]] data were supplemented by botanical traits for a robust initial classification, then genetic, [[Cell biology|cytological]], protein and DNA evidence was added. Now, the categories are forms (little used), races, racial complexes, and recently branches.{{Citation needed|date=January 2021}}

Maize is a [[diploid]] with 20 [[chromosome]]s (n=10). The combined length of the chromosomes is 1500 [[Centimorgan|cM]]. Some of the maize chromosomes have what are known as "chromosomal knobs": highly repetitive [[heterochromatin|heterochromatic]] domains that stain darkly. Individual knobs are [[Polymorphism (biology)|polymorphic]] among strains of both maize and [[teosinte]].{{Citation needed|date=January 2021}} Hufford ''et al.'', 2012 finds that 83% of [[allelic variation]] within the genome derives from its teosinte ancestors, primarily due to the freedom of ''Zea''s to [[outcross]].<ref name="Back-to-the-Wild" >{{cite journal |last1=Wani |first1=Shabir Hussain |last2=Samantara |first2=Kajal |last3=Razzaq |first3=Ali |last4=Kakani |first4=Grihalakshmi |last5=Kumar |first5=Pardeep |title=Back to the wild: mining maize (''Zea mays'' L.) disease resistance using advanced breeding tools |journal=[[Molecular Biology Reports]]|date=June 2022 |volume=49 |issue=6 |pages=5787–5803 |doi=10.1007/s11033-021-06815-x |pmid=35064401 |s2cid=254834535 }}</ref>

[[Barbara McClintock]] used these knob markers to validate her [[transposon]] theory of "jumping genes", for which she won the 1983 [[Nobel Prize in Physiology or Medicine]]. Maize is still an important [[model organism]] for genetics and [[developmental biology]] today.<ref>{{cite news |url=https://www.washingtonpost.com/wp-dyn/content/article/2009/11/19/AR2009111903190.html |title=Scientists have high hopes for corn genome |first=David |last=Brown |newspaper=[[The Washington Post]] |date=November 20, 2009}}</ref>

The [[centromere]]s have two types of structural components, both of which are found only in the centromeres: Large arrays of CentC, a short [[satellite DNA]]; and a few of a family of [[retrotransposon]]s. The [[maize B chromosome|B chromosome]], unlike the others, contains an additional repeat which extends into neighboring areas of the chromosome. Centromeres can accidentally shrink during division and still function, although it is thought this will fail if it shrinks below a few hundred [[kilobase]]. [[Kinetochore]]s contain RNA originating from centromeres. Centromere regions can become inactive, and can continue in that state if the chromosome still has another active one.<ref name="Birchler-Han-2009">{{cite journal |last1=Birchler |first1=James A. |last2=Han |first2=Fangpu |title=Maize Centromeres: Structure, Function, Epigenetics |journal=[[Annual Review of Genetics]]|date=1 December 2009 |volume=43 |issue=1 |pages=287–303 |doi=10.1146/annurev-genet-102108-134834 |pmid=19689211 }}</ref>

The Maize Genetics Cooperation Stock Center, funded by the USDA [[Agricultural Research Service]] and located in the Department of Crop Sciences at the [[University of Illinois at Urbana-Champaign]], is a stock center of maize mutants. The total collection has nearly 80,000 samples. The bulk of the collection consists of several hundred named genes, plus additional gene combinations and other heritable variants. There are about 1000 chromosomal aberrations (e.g., translocations and inversions) and stocks with abnormal chromosome numbers (e.g., [[tetraploid]]s). Genetic data describing the maize mutant stocks as well as myriad other data about maize genetics can be accessed at [http://maizegdb.org/ MaizeGDB], the Maize Genetics and Genomics Database.<ref>{{Cite web|url=https://www.maizegdb.org/|title=Welcome to MaizeGDB|website=[[MaizeGDB]]}}</ref>

In 2005, the US [[National Science Foundation]] (NSF), Department of Agriculture ([[United States Department of Agriculture|USDA]]) and the [[United States Department of Energy|Department of Energy]] (DOE) formed a consortium to sequence the [[B73 (maize)|B73]] maize [[genome]]. The resulting DNA sequence data was deposited immediately into [[GenBank]], a public repository for genome-sequence data. Sequences and genome annotations have also been made available throughout the project's lifetime at the project's official site.<ref>{{cite web|url=http://www.maizesequence.org/index.html|title=Welcome to MaizeSequence.org|publisher=MaizeSequence.org|access-date=September 21, 2013}}</ref>

Primary sequencing of the maize genome was completed in 2008.<ref>{{cite news|url=https://www.reuters.com/article/rbssIndustryMaterialsUtilitiesNews/idUSN2632641520080226|title=Researchers sequence genome of maize, a key crop|newspaper=Reuters|access-date=October 6, 2014|date=2008-02-26}}</ref> On November 20, 2009, the consortium published results of its sequencing effort in ''Science''.<ref>{{cite journal|doi=10.1126/science.1178534|title=The B73 Maize Genome: Complexity, Diversity, and Dynamics|year=2009|last1=Schnable|first1=P. S.|last2=Ware|first2=D.|last3=Fulton|first3=R. S.|last4=Stein|first4=J. C.|last5=Wei|first5=F.|last6=Pasternak|first6=S.|last7=Liang|first7=C.|last8=Zhang|first8=J.|last9=Fulton|first9=L.|last10=Graves|first10=T. A.|last11=Minx|first11=P.|last12=Reily|first12=A. D.|last13=Courtney|first13=L.|last14=Kruchowski|first14=S. S.|last15=Tomlinson|first15=C.|last16=Strong|first16=C.|last17=Delehaunty|first17=K.|last18=Fronick|first18=C.|last19=Courtney|first19=B.|last20=Rock|first20=S. M.|last21=Belter|first21=E.|last22=Du|first22=F.|last23=Kim|first23=K.|last24=Abbott|first24=R. M.|last25=Cotton|first25=M.|last26=Levy|first26=A.|last27=Marchetto|first27=P.|last28=Ochoa|first28=K.|last29=Jackson|first29=S. M.|last30=Gillam|first30=B.|display-authors=3|journal=[[Science (journal)|Science]]|volume=326|issue=5956|pages=1112–5|pmid=19965430|bibcode=2009Sci...326.1112S|s2cid=21433160|url=https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1206&context=stat_las_pubs}}</ref> The genome, 85% of which is composed of [[transposon]]s, was found to contain 32,540 genes (By comparison, the [[human genome]] contains about 2.9 billion bases and 26,000 genes). Much of the maize genome has been duplicated and reshuffled by [[Helitron (biology)|helitrons]]—group of rolling circle transposons.<ref>{{cite journal |last1=Feschotte |first1=C. |last2=Pritham |first2=E. |title=A cornucopia of Helitrons shapes the maize genome |journal=[[Proceedings of the National Academy of Sciences]] |volume=106 |issue=47 |pages=19747–19748 |year=2009 |pmid=19926864 |pmc=2785235 |doi=10.1073/pnas.0910273106|bibcode=2009PNAS..10619747F|doi-access=free }}</ref>

In ''Z. mays'' and various other angiosperms the [[MADS-box]] motif is involved in floral development. Early study in several angiosperm models including ''Z. mays'' was the beginning of research into the molecular evolution of floral structure in general, as well as their role in nonflowering plants.<ref name="Friedman-et-al-2004">{{cite journal|date=October 2004|publisher=[[John Wiley & Sons, Inc.]]|last1=Friedman |first1=William E. |last2=Moore |first2=Richard C. |last3=Purugganan |first3=Michael D. |title=The evolution of plant development |journal=[[American Journal of Botany]]|volume=91 |issue=10 |pages=1726–1741 |doi=10.3732/ajb.91.10.1726 |pmid=21652320 |doi-access=free|id=[[Botanical Society of America]]}}</ref>

Varieties differ in their [[insect resistance in crops|resistance to insects]], including [[borer (diambiguation)#Insects|borers]].<ref name="Breeding-Towards" /> [[CIMMYT]] maintains a large collection of maize/corn accessions tested and cataloged for insect resistance.<ref name="Breeding-Towards" >{{cite journal |last1=Prasanna |first1=Boddupalli M. |last2=Bruce |first2=Anani |last3=Beyene |first3=Yoseph |last4=Makumbi |first4=Dan |last5=Gowda |first5=Manje |last6=Asim |first6=Muhammad |last7=Martinelli |first7=Samuel |last8=Head |first8=Graham P. |last9=Parimi |first9=Srinivas |title=Host plant resistance for fall armyworm management in maize: relevance, status and prospects in Africa and Asia |journal=[[Theoretical and Applied Genetics]] |date=November 2022 |volume=135 |issue=11 |pages=3897–3916 |doi=10.1007/s00122-022-04073-4 |pmid=35320376 |pmc=9729323 }}</ref>

[[Kompetitive Allele Specific PCR]] (KASP) is useful for [[single nucleotide polymorphism]] (SNP) typing for [[molecular breeding]] in this crop.<ref name="Overview"/> Semagn ''et al.'', 2013 describes methods and practices.<ref name="Overview">{{cite journal|issue=1|year=2013|publisher=[[Springer Science and Business Media LLC]]|volume=33|last1=Semagn|first1=Kassa|last2=Babu|first2=Raman|last3=Hearne|first3=Sarah|last4=Olsen|first4=Michael|pages=1–14|title=Single nucleotide polymorphism genotyping using Kompetitive Allele Specific PCR (KASP): overview of the technology and its application in crop improvement|s2cid=14272035|doi=10.1007/s11032-013-9917-x|journal=[[Molecular Breeding]]|issn=1380-3743|id=National Key Laboratory of Crop Genetic Improvement at [[Huazhong Agricultural University]]}}</ref>

Svitashev ''et al.'', 2016 demonstrates the integration of [[genome editing]] using ([[CRISPR–Cas9]]) into the breeding process for this crop.<ref>
:{{Cite journal|year=2019|publisher=[[Annual Reviews (publisher)|Annual Reviews]]|s2cid=73471425|pmid=30835493|journal=[[Annual Review of Plant Biology]]|doi=10.1146/annurev-arplant-050718-100049|title=CRISPR/Cas Genome Editing and Precision Plant Breeding in Agriculture |last1=Chen |first1=Kunling |last2=Wang |first2=Yanpeng |last3=Zhang |first3=Rui |last4=Zhang |first4=Huawei |last5=Gao |first5=Caixia |volume=70 |pages=667–697 |doi-access=free }}
:
:This review cites this research.
:
:{{Cite journal|year=2016|publisher=[[Nature Portfolio]]|journal=[[Nature Communications]]|s2cid=37440895|doi=10.1038/ncomms13274|title=Genome editing in maize directed by CRISPR–Cas9 ribonucleoprotein complexes |last1=Svitashev |first1=Sergei |last2=Schwartz |first2=Christine |last3=Lenderts |first3=Brian |last4=Young |first4=Joshua K. |last5=Mark Cigan |first5=A. |volume=7 |page=13274 |pmid=27848933 |pmc=5116081 |bibcode=2016NatCo...713274S }}
</ref>

==Evolution==
As with many plants and animals, ''Z. mays'' has a positive correlation between [[effective population size]] and the magnitude of [[selection pressure]]. ''Z. m.'' having an EPS of ~650,000, it clusters with others of about the same EPS, and has 79% of its [[amino acid]] sites under selection.<ref name="Hough-et-al-2013">{{cite journal |last1=Hough |first1=Josh |last2=Williamson |first2=Robert J. |last3=Wright |first3=Stephen I. |title=Patterns of Selection in Plant Genomes |journal=Annual Review of Ecology, Evolution, and Systematics |date=23 November 2013 |volume=44 |issue=1 |pages=31–49 |doi=10.1146/annurev-ecolsys-110512-135851 }}</ref>

[[Homologous recombination|Recombination]] is a significant source of [[genetic diversity|diversity]] in ''Z. mays''. (Note that this finding supersedes previous studies which showed no such correlation.)<ref name="Hough-et-al-2013" />

This recombination/diversity effect is seen throughout plants but is also found to not occur – or not as strongly – in regions of high [[gene density]]. This is likely the reason that domesticated ''Z. mays'' has not seen as much of an increase in diversity within areas of higher density as in regions of lower density, although there is more evidence in other plants.<ref name="Hough-et-al-2013" />

Some lines of maize have undergone ancient [[polyploid]]y events, starting 11 million years ago. Over that time ~72% of polyploid duplicated genes have been retained, which is higher than other plants with older polyploidy events. Thus maize ''may'' be due to lose more duplicate genes as time goes along, similar to the course followed by the genomes of other plants. If so - if gene loss has merely not occurred yet - that could explain the lack of observed [[positive selection]] and lower [[negative selection (natural selection)|negative selection]] which are observed in otherwise similar plants, i.e. also naturally [[outcrossing]] and with similar effective population sizes.<ref name="Hough-et-al-2013" />

Ploidy does not appear to influence EPS or magnitude of selection effect in maize.<ref name="Hough-et-al-2013" />

== Breeding ==
Maize reproduces sexually each year. This randomly selects half the genes from a given plant to propagate to the next generation, meaning that desirable traits found in the crop (like high yield or good nutrition) can be lost in subsequent generations unless certain techniques are used.{{Citation needed|date=January 2021}}

Maize breeding in prehistory resulted in large plants producing large ears. Modern breeding began with individuals who selected highly productive varieties in their fields and then sold seed to other farmers. James L. Reid was one of the earliest and most successful developing Reid's Yellow Dent in the 1860s. These early efforts were based on [[Selection methods in plant breeding based on mode of reproduction|mass selection]]. Later breeding efforts included ear to row selection (C. G. Hopkins c. 1896), hybrids made from selected [[inbred]] lines (G. H. Shull, 1909), and the highly successful double cross hybrids using four inbred lines ([[Donald F. Jones|D. F. Jones]] c. 1918, 1922). University supported breeding programs were especially important in developing and introducing modern hybrids.<ref name="Jugen">{{cite book |last1=Jugenheimer |first1=Robert W. |title=Hybrid Maize Breeding and Seed Production |date=1958 |publisher=Food and Agriculture Organization, United Nations |location=Rome |language=en |chapter=Agr. Dev. Paper #62}}</ref> By the 1930s, companies such as [[Pioneer Hi-Bred|Pioneer]] devoted to production of hybrid maize had begun to influence long-term development. Internationally important seed banks such as the [[International Maize and Wheat Improvement Center]] (CIMMYT) and the US bank at the Maize Genetics Cooperation Stock Center [[University of Illinois at Urbana-Champaign]] maintain [[germplasm]] important for future crop development.{{Citation needed|date=January 2021}}

Since the 1940s the best strains of maize have been first-generation hybrids made from inbred strains that have been optimized for specific traits, such as yield, nutrition, drought, pest and disease tolerance. Both conventional cross-breeding and genetic engineering have succeeded in increasing output and reducing the need for cropland, pesticides, water and fertilizer.<ref name=nyt14 /> There is conflicting evidence to support the hypothesis that maize yield potential has increased over the past few decades. This suggests that changes in yield potential are associated with leaf angle, lodging resistance, tolerance of high plant density, disease/pest tolerance, and other agronomic traits rather than increase of yield potential per individual plant.<ref>{{cite journal |doi=10.2135/cropsci1999.3961622x |author=Duvick, D. N. |author2=Cassman, K. G. |title=Post-green-revolution trends in yield potential of temperate maize in the north-central United States |journal=[[Crop Science (journal)|Crop Science]] |volume=39 |pages=1622–1630 |year=2009 |url=http://crop.scijournals.org/cgi/content/abstract/39/6/1622 |issue=6 |s2cid=39657597 |url-status=dead |archive-url=https://web.archive.org/web/20091115003659/http://crop.scijournals.org/cgi/content/abstract/39/6/1622 |archive-date=November 15, 2009 |df=mdy-all}}</ref>

Certain varieties of maize have been bred to produce many ears which are the source of the "[[baby corn]]" used as a vegetable in [[Asian cuisine]].<ref>{{Cite book|last=Maiti|first=Ratikanta|url=https://books.google.com/books?id=8_m7aIfR7xEC&pg=PA52|title=Crop Plant Anatomy|date=2012|publisher=CABI|isbn=978-1-78064-174-4|language=en}}</ref>

One strain called olotón has evolved a symbiotic relationship with [[Nitrogen fixation|nitrogen-fixing]] microbes, which provides the plant with 29%–82% of its nitrogen.<ref>{{cite journal | doi=10.1371/journal.pbio.2006352 | title=Nitrogen fixation in a landrace of maize is supported by a mucilage-associated diazotrophic microbiota | year=2018 | last1=Van Deynze | first1=Allen | last2=Zamora | first2=Pablo | last3=Delaux | first3=Pierre-Marc | last4=Heitmann | first4=Cristobal | last5=Jayaraman | first5=Dhileepkumar | last6=Rajasekar | first6=Shanmugam | last7=Graham | first7=Danielle | last8=Maeda | first8=Junko | last9=Gibson | first9=Donald | last10=Schwartz | first10=Kevin D. | last11=Berry | first11=Alison M. | last12=Bhatnagar | first12=Srijak | last13=Jospin | first13=Guillaume | last14=Darling | first14=Aaron | last15=Jeannotte | first15=Richard | last16=Lopez | first16=Javier | last17=Weimer | first17=Bart C. | last18=Eisen | first18=Jonathan A. | last19=Shapiro | first19=Howard-Yana | last20=Ané | first20=Jean-Michel | last21=Bennett | first21=Alan B. | journal=PLOS Biology | volume=16 | issue=8 | pages=e2006352 | pmid=30086128 | pmc=6080747 | doi-access=free }}</ref>

CIMMYT operates a conventional breeding program to provide optimized strains. The program began in the 1980s. Hybrid seeds are distributed in Africa by the Drought Tolerant Maize for Africa project.<ref name=nyt14>{{cite news |title=A Green Revolution, This Time for Africa |first=Tina |last=Rosenberg |date=April 9, 2014 |url=http://opinionator.blogs.nytimes.com/2014/04/09/a-green-revolution-this-time-for-africa/}}</ref>

=== Genetic engineering ===
{{Main|Transgenic maize}}
[[Genetically engineered]] [[Genetically modified maize|(GE) maize]] was one of the 26 [[Genetically engineered food|GE crops]] grown commercially in 2016.<ref name="James-2016">{{Cite web|url=http://www.isaaa.org/resources/publications/briefs/52/executivesummary/default.asp|title=Global Status of Commercialized Biotech/GM Crops: 2016 – ISAAA Brief 52-2016|last=James|first=Clive|date=2016 |publisher=ISAAA |archive-url=https://web.archive.org/web/20170504055752/http://www.isaaa.org/resources/publications/briefs/52/executivesummary/default.asp|archive-date=2017-05-04|url-status=dead|access-date=2017-08-26}}</ref><ref>[http://www.isaaa.org/resources/publications/briefs/43/executivesummary/default.asp ISAAA Brief 43-2011]: Executive Summary, retrieved September 9, 2012</ref> The vast majority of this is [[Bt maize]]. Grown since 1997 in the United States and Canada,<ref name="Ostry-et-al-2015" /> 92% of the US maize crop was genetically modified in 2016<ref name="James-2016" /><ref>{{cite web|url=http://usda.mannlib.cornell.edu/usda/nass/Acre/2010s/2010/Acre-06-30-2010.pdf|title=National Agricultural Statistics Service (NASS), Agricultural Statistics Board, US Department of Agriculture, Acreage report for 2010}}</ref> and 33% of the worldwide maize crop was GM in 2016.<ref name="James-2016" /><ref>{{cite web|url=http://www.isaaa.org/resources/publications/biotech_crop_annual_update/download/02_Corn_2012.pdf |title=ISAAA Biotech Maize Update 2011 |access-date=October 6, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20130524170600/http://www.isaaa.org/resources/publications/biotech_crop_annual_update/download/02_Corn_2012.pdf |archive-date=May 24, 2013 }}</ref> As of 2011, Herbicide-tolerant maize varieties were grown in Argentina, Australia, Brazil, Canada, China, Colombia, El Salvador, the European Union, Honduras, Japan, Korea, Malaysia, Mexico, New Zealand, Philippines, the Russian Federation, Singapore, South Africa, Taiwan, Thailand, and the United States. Insect-resistant maize was grown in Argentina, Australia, Brazil, Canada, Chile, China, Colombia, Egypt, the European Union, Honduras, Japan, Korea, Malaysia, Mexico, New Zealand, Philippines, South Africa, Switzerland, Taiwan, the United States, and Uruguay.<ref>{{cite web|url=http://www.isaaa.org/resources/publications/pocketk/2/default.asp|title=ISAAA Pocket K No. 2: Plant Products of Biotechnology, 2011|access-date=October 6, 2014}}</ref>

In September 2000, up to $50 million worth of food products were recalled due to the presence of [[StarLink corn recall|Starlink]] genetically modified corn, which had been approved only for animal consumption and had not been approved for human consumption, and was subsequently withdrawn from the market.<ref>Andrew Pollack (September 23, 2000). [https://www.nytimes.com/2000/09/23/business/kraft-recalls-taco-shells-with-bioengineered-corn.html "Kraft Recalls Taco Shells With Bioengineered Corn"]. ''The New York Times''.</ref>

=== For pest and disease resistance ===
Tropical [[landrace]]s remain an important and underused source of resistance alleles {{ndash}} both those [[plant disease resistance|for disease]] and [[plant defense against herbivory|for herbivores]].<ref name="Chakradhar-et-al-2017"/> Notable discoveries of rare alleles for this purpose were made by Dao ''et al.'', 2014 and Sood ''et al.'', 2014.<ref name="Chakradhar-et-al-2017">{{cite journal |last1=Chakradhar |first1=Thammineni |last2=Hindu |first2=Vemuri |last3=Reddy |first3=Palakolanu Sudhakar |title=Genomic-based-breeding tools for tropical maize improvement |journal=Genetica |date=December 2017 |volume=145 |issue=6 |pages=525–539 |doi=10.1007/s10709-017-9981-y |pmid=28875394 |s2cid=24074330 |url=http://oar.icrisat.org/10349/1/10.1007%252Fs10709-017-9981-y.pdf }}</ref> Rashid ''et al.'', 2018 use an [[association mapping]] panel from [[CIMMYT]] originally developed for tropical drought tolerance traits to find new [[genome|genomic]] regions providing [[sorghum downy mildew resistance]], and to further characterize SDMR regions already located by others.<ref name="Kole-2020">{{cite book |editor-last=Kole |editor-first=Chittaranjan |title=Genomic Designing of Climate-Smart Cereal Crops |publisher=[[Springer International Publishing|Springer]] |publication-place=[[Cham, Switzerland]] |year=2020 |isbn=978-3-319-93380-1}} {{ISBN|978-3-319-93381-8}}.</ref>

== Origin ==
{{See also|Teosinte#Origin_of_maize_and_interaction_with_teosintes|l1=Origin of maize and interaction with teosintes}}

[[File:Maize-teosinte.jpg|thumb|[[Teosinte]] (top), maize-teosinte hybrid (middle), maize (bottom)]]

Maize is the [[crop domestication|domesticated variant]] of [[teosinte]] {{endash}} teosintes are the [[crop wild relative]]s of this plant.<ref name=corn>{{cite journal |last1=Whipple |first1=Clinton J. |last2=Kebrom |first2=Tesfamichael H. |last3=Weber |first3=Allison L. |last4=Yang |first4=Fang |last5=Hall |first5=Darren |last6=Meeley |first6=Robert |last7=Schmidt |first7=Robert |last8=Doebley |first8=John |last9=Brutnell |first9=Thomas P. |last10=Jackson |first10=David P. |title=grassy tillers1 promotes apical dominance in maize and responds to shade signals in the grasses |journal=Proceedings of the National Academy of Sciences |date=16 August 2011 |volume=108 |issue=33 |pages=E506-12 |doi=10.1073/pnas.1102819108 |pmid=21808030 |pmc=3158142 |doi-access=free }}
*{{cite news |first=Emma|last=Penrod|date=September 14, 2011 |title=Study of corn genetics has implications for biofuel research |newspaper=The Daily Universe |url=https://universe.byu.edu/index.php/2011/09/14/study-of-corn-genetics-has-implications-for-biofuel-research/}}</ref> The two plants have dissimilar appearance, maize having a single tall stalk with multiple leaves and teosinte being a short, bushy plant. The difference between the two is largely controlled by differences in just two genes, called grassy tillers-1 (''gt1'', {{UniProt|A0A317YEZ1}}) and teosinte branched-1 (''tb1'', {{UniProt|Q93WI2}}).<ref name="corn" />

Several theories had been proposed about the specific origin of maize in Mesoamerica:<ref name="wilkes">{{cite book|editor-first=C. Wayne |editor-last=Smith|title=Corn: Origin, History, Technology, and Production|chapter-url={{google books |plainurl=y |id=eDJ3NjHh8H8C}}|date=8 March 2004|publisher=[[John Wiley & Sons]]|isbn=978-0-471-41184-0|first=Garrison |last=Wilkes |chapter=Chapter 1.1 Corn, strange and marvelous: but is a definitive origin known? |pages=3–63 |editor2-first=Javier |editor2-last=Betrán |editor3-first=E.&nbsp;C.&nbsp;A. |editor3-last=Runge}}</ref><ref name="Hyams1990">{{cite book|first=Edward |last=Hyams|title=The Last of the Incas: The Rise and Fall of an American Empire|url={{google books |plainurl=y |id=mlZKAAAAYAAJ}}|year=1990|publisher=[[Dorset Press]]|isbn=978-0-88029-595-6}}</ref>
# It is a direct domestication of a [[flora of Mexico|Mexican]] annual teosinte, [[Zea mays ssp. parviglumis|''Z. m.'' ssp. ''parviglumis'']], native to the [[Balsas River]] valley in south-eastern Mexico,<ref name="Wu-et-al-2011" /> with up to 12% of its [[genetic material]] obtained from [[Zea mays ssp. mexicana|''Z. m.'' ssp. ''mexicana'']] through [[introgression]].<ref name="Mat" />
# It has been derived from [[Hybridization (biology)|hybridization]] between a small domesticated maize (a slightly changed form of a wild maize) and a teosinte of section ''[[Luxuriantes (Zea)|Luxuriantes]]'', either [[Zea luxurians|''Z. luxurians'']] or ''[[Zea diploperennis|Z. diploperennis]]''.
# It has undergone two or more domestications either of a wild maize or of a teosinte. (The term "teosinte" describes all [[species]] and subspecies in the genus ''Zea'', excluding [[Zea mays ssp. mays|''Z. m.'' ssp. ''mays'']].)
# It has evolved from a hybridization of ''Z. diploperennis'' by ''[[Tripsacum dactyloides]]''.
In the late 1930s, [[Paul Mangelsdorf]] suggested that domesticated maize was the result of a hybridization event between an unknown wild maize and a species of ''[[Tripsacum]]'', a related genus. This theory about the origin of maize has been refuted by modern [[genetic testing]], which refutes Mangelsdorf's model and the fourth listed above.<ref name="wilkes" />{{rp|40}}

The teosinte origin theory was proposed by the Russian botanist [[Nikolai Ivanovich Vavilov]] in 1931 and the later American [[Nobel Prize]]-winner [[George Beadle]] in 1932.<ref name="wilkes" />{{rp|10}} It is supported experimentally and by recent studies of the plants' genomes. Teosinte and maize [[interfertility|can cross-breed and produce fertile offspring]]. A number of questions remain concerning the species, among them:
# how the immense [[genetic diversity|diversity]] of the species of sect. ''Zea'' originated,
# how the tiny archaeological specimens of 3500–2700 BC could have been selected from a teosinte, and
# how domestication could have proceeded without leaving remains of teosinte or maize with teosintoid traits earlier than the earliest known until recently, dating from ca. 1100 BC.

The [[domestication]] of maize is of particular interest to researchers—[[archaeologist]]s, [[geneticist]]s, [[ethnobotany|ethnobotanists]], geographers, etc. The process is thought by some to have started 7,500 to 12,000 years ago. Research from the 1950s to 1970s originally focused on the hypothesis that maize domestication occurred in the highlands between the states of [[Oaxaca]] and [[Jalisco]], because the oldest archaeological remains of maize known at the time were found there.

{{ Anchor | Zea mays subsp. parviglumis | Zea mays ssp. parviglumis | parviglumis }}
=== Connection with 'parviglumis' subspecies ===
Genetic studies, published in 2004 by [[John Doebley]], identified [[Zea mays ssp. parviglumis|''Zea mays'' ssp. ''parviglumis'']], native to the [[Balsas River]] valley in Mexico's southwestern highlands, and also known as Balsas teosinte, as being the [[crop wild relative]] that is genetically most similar to modern maize.<ref>{{cite journal |last=Doebley |first=John F. |author-link=John Doebley |title=The genetics of maize evolution |url=http://teosinte.wisc.edu/pdfs/DoebleyAnnRev2004.pdf |journal=[[Annual Review of Genetics]]|year=2004 |volume=38 |pmid=15568971 |pages=37–59 |doi=10.1146/annurev.genet.38.072902.092425}}</ref><ref name="Wu-et-al-2011">{{cite journal |last1=Wu |first1=Chi-Chih |last2=Diggle |first2=Pamela K. |last3=Friedman |first3=William E. |title=Female gametophyte development and double fertilization in Balsas teosinte, ''Zea mays'' subsp. ''parviglumis'' (Poaceae)|journal=[[Sexual Plant Reproduction]]|date=September 2011 |volume=24 |issue=3 |pages=219–229 |doi=10.1007/s00497-011-0164-1 |pmid=21380710 |s2cid=8045294 }}</ref> This was confirmed by further studies, which refined this hypothesis somewhat. Archaeobotanical studies, published in 2009, point to the middle part of the Balsas River valley as the likely location of early domestication; this river is not very long, so these locations are not very distant. Stone milling tools with maize residue have been found in an 8,700 year old layer of deposits in a cave not far from [[Iguala, Guerrero]].<ref>{{cite web|url=http://www.eurekalert.org/pub_releases/2009-03/nsf-wgb032309.php|title="Wild grass became maize crop more than 8,700 years ago", National Science Foundation, News Release at ''Eurekalert'' March 24, 2009|date=March 23, 2009|access-date=October 6, 2014}}</ref><ref name="Ranere">{{cite journal |last1=Ranere |first1=Anthony J. |first2=Dolores R. |last2=Piperno |first3=Irene |last3=Holst |first4=Ruth |last4=Dickau |first5=José |last5=Iriarte |display-authors=3 |title=The cultural and chronological context of early Holocene maize and squash domestication in the Central Balsas River Valley, Mexico |journal=[[Proceedings of the National Academy of Sciences]] |year=2009 |volume=106 |pmid=19307573 |issue=13 |pages=5014–5018 |pmc=2664064 |doi=10.1073/pnas.0812590106|bibcode=2009PNAS..106.5014R|doi-access=free }}</ref><ref>{{cite journal |last1=Ranere |first1=Anthony J. |first2=Dolores R. |last2=Piperno |first3=Irene |last3=Holst |first4=Ruth |last4=Dickau |first5=José |last5=Iriarte |display-authors=3 |title=Starch grain and phytolith evidence for early ninth millennium B.P. maize from the Central Balsas River Valley, Mexico |journal=[[Proceedings of the National Academy of Sciences]] |year=2009 |volume=106 |pmid=19307570 |issue=13 |pages=5019–5024 |pmc=2664021 |doi=10.1073/pnas.0812525106|bibcode=2009PNAS..106.5019P|doi-access=free }}</ref>

[[File:Mayan - Stucco Portrait Head - Walters 20092026 - Three Quarter Right.jpg|thumb|upright|left|Stucco head of the [[Maya Maize God]], 550–850 AD]]

Doebley was part of the team that first published, in 2002, that maize had been domesticated only once, about 9,000 years ago, and then spread throughout the Americas.<ref name="Mat" /><ref>Michael Balter, [https://www.science.org/content/article/corn-its-not-cocktails ''Corn: It's Not for Cocktails.''] March 23, 2009 news.sciencemag.org</ref>

A primitive corn was being grown in southern Mexico, Central America, and northern South America 7,000 years ago. Archaeological remains of early maize ears, found at [[Guila Naquitz Cave]] in the [[Oaxaca Valley]], date back roughly 6,250 years; the oldest ears from caves near [[Tehuacán, Puebla|Tehuacan]], Puebla, 5,450 [[Before Present|B.P.]]<ref name="archsouth" />

Maize pollen dated to 7,300 B.P. from [[San Andrés (Mesoamerican site)|San Andres, Tabasco]], on the Caribbean coast has also been recovered.<ref name="Ranere" />

[[File:Young Corn God MET DT9945.jpg|thumb|upright|[[Jaina Island]] ceramic statuette of the young Maya Maize God emerging from an ear of corn, 600–900 A.D.]]

As maize was introduced to new cultures, new uses were developed and new varieties selected to better serve in those preparations. Maize was the staple food, or a major staple – along with [[Squash (plant)|squash]], Andean region [[potato]], [[quinoa]], [[bean]]s, and [[amaranth]] – of most [[pre-Columbian]] North American, Mesoamerican, South American, and Caribbean cultures. The Mesoamerican civilization, in particular, was deeply interrelated with maize. Its traditions and rituals involved all aspects of maize cultivation – from the planting to the food preparation. Maize formed the Mesoamerican people's identity.{{Citation needed|date=January 2021}}

It is unknown what precipitated its domestication, because the edible portion of the wild variety is too small, and hard to obtain, to be eaten directly, as each kernel is enclosed in a very hard bivalve shell.{{Citation needed|date=January 2021}}

In 1939, George Beadle demonstrated that the kernels of teosinte are readily "popped" for human consumption, like modern popcorn.<ref>Norman H. Horowitz, [http://www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/beadle-g-w.pdf George Wells Beadle 1903–1989 (PDF)]. National Academy of Sciences.</ref> Some have argued it would have taken too many generations of [[selective breeding]] to produce large, compressed ears for efficient cultivation. However, studies of the hybrids readily made by intercrossing teosinte and modern maize suggest this objection is not well founded.{{Citation needed|date=January 2021}}

=== Spreading to the north ===
Around 4,500 years ago, maize began to spread to the north. Maize was first cultivated in what is now the United States at several sites in New Mexico and Arizona about 4,100 years ago.<ref>Roney, p. 4</ref>

During the first millennium AD, maize cultivation spread more widely in the areas north. In particular, the large-scale adoption of maize agriculture and consumption in eastern North America took place about A.D. 900. Native Americans cleared large forest and grassland areas for the new crop.<ref>{{cite journal |last1=Emerson |first1=Thomas E. |last2=Hedman |first2=Kristin M. |last3=Simon |first3=Mary L. |title=Marginal Horticulturalists or Maize Agriculturalists? Archaeobotanical, Paleopathological, and Isotopic Evidence Relating to Langford Tradition Maize Consumption |journal=[[Midcontinental Journal of Archaeology]]|date=2005 |volume=30 |issue=1 |pages=67–118 |doi=10.1179/mca.2005.003 |jstor=20708222 |s2cid=129150225 }}</ref>

In 2005, research by the [[United States Department of Agriculture|USDA]] [[United States Forest Service|Forest Service]] suggested that the rise in maize cultivation 500 to 1,000 years ago in what is now the southeastern United States corresponded with a decline of freshwater [[mussel]]s, which are very sensitive to environmental changes.<ref>{{cite journal |author=Evan Peacock |author2=Wendell R. Haag |author3=Melvin L. Warren Jr |year=2005 |title=Prehistoric decline in freshwater mussels coincident with the advent of maize agriculture |journal=[[Conservation Biology (journal)|Conservation Biology]] |volume=19 |issue=2 |pages=547–551 |url=http://www.srs.fs.usda.gov/pubs/ja/ja_peacock001.pdf |doi=10.1111/j.1523-1739.2005.00036.x|s2cid=3679709 }}</ref>

== Cultivation ==

=== Planting ===
[[File:Plàntules moresc 2012.JPG|thumb|Seedlings three weeks after sowing]]
[[File:Corn Zea mays Plant Row 2000px.jpg|right|thumb|upright|Young stalks]]
Because it is cold-intolerant, in the [[Temperate|temperate zones]] maize must be planted in the spring. Its [[root]] system is generally shallow, so the plant is dependent on soil moisture. As a plant that uses [[C4 carbon fixation]], maize is a considerably more water-efficient crop than plants that use [[C3 carbon fixation]] such as [[alfalfa]] and [[soybeans]]. Maize is most sensitive to drought at the time of silk emergence, when the flowers are ready for pollination. In the United States, a good harvest was traditionally predicted if the maize was "knee-high by the [[Independence Day (United States)|Fourth of July]]", although modern [[Hybrid (biology)|hybrids]] generally exceed this growth rate. Maize used for [[silage]] is harvested while the plant is green and the fruit immature. Sweet corn is harvested in the "milk stage", after pollination but before starch has formed, between late summer and early to mid-autumn. Field maize is left in the field until very late in the autumn to thoroughly dry the grain, and may, in fact, sometimes not be harvested until winter or even early spring. The importance of sufficient soil moisture is shown in many parts of Africa, where periodic [[drought]] regularly causes maize crop failure and consequent [[famine]]. Although it is grown mainly in wet, hot climates, it has been said to thrive in cold, hot, dry or wet conditions, meaning that it is an extremely versatile crop.<ref>Fernandez-Armesto, Felipe (2011). "The World: A History", p. 470. Penguin Academics, London. {{ISBN|0-205-75930-0}}</ref>

[[File:Maispflanze.jpg|left|thumb|upright|Mature plants showing ears]]
Maize was planted by the [[Native American (Americas)|Native Americans]] in hills, in a complex system known to some as the [[Three Sisters (agriculture)|Three Sisters]].<ref>{{Cite web|last=Hill|first=Christina Gish|date=2020-11-20|title=Returning the 'three sisters' – corn, beans and squash – to Native American farms nourishes people, land and cultures|url=http://theconversation.com/returning-the-three-sisters-corn-beans-and-squash-to-native-american-farms-nourishes-people-land-and-cultures-149230 |access-date=2021-01-09|website=The Conversation|language=en}}</ref> Maize provided support for [[bean]]s, and the beans provided nitrogen derived from nitrogen-fixing [[rhizobia]] bacteria which live on the roots of beans and other [[legume]]s; and [[Squash (fruit)|squashes]] provided ground cover to stop weeds and inhibit evaporation by providing shade over the soil.<ref name=Mann_2011>{{cite book |title=1491: New Revelations of the Americas Before Columbus |edition=2nd |author-link=Charles C. Mann |first=Charles C. |last=Mann |chapter=Cotton (or Anchovies) and Maize |pages=[https://archive.org/details/149100char/page/225 225–229] |date=July 2011 |publisher=[[Vintage Books]] |isbn=978-1-4000-3205-1 |location=New York |title-link=1491: New Revelations of the Americas Before Columbus}}</ref> This method was replaced by single species hill planting where each hill {{convert|60|–|120|cm|ftin|abbr=on}} apart was planted with three or four seeds, a method still used by home gardeners. A later technique was "checked maize", where hills were placed {{convert|40|in|m|abbr=on|0|order=flip}} apart in each direction, allowing cultivators to run through the field in two directions. In more arid lands, this was altered and seeds were planted in the bottom of {{convert|10|–|12|cm|in|frac=2|abbr=on}} deep furrows to collect water. Modern technique plants maize in rows which allows for cultivation while the plant is young, although the hill technique is still used in the maize fields of some Native American reservations. When maize is planted in rows, it also allows for planting of other crops between these rows to make more efficient use of land space.<ref>{{cite journal|last1=Diderot|first1=Denis|title=Maize|url=http://quod.lib.umich.edu/d/did/did2222.0002.667/--maize?rgn=main;view=fulltext;q1=Agriculture|journal=Encyclopedia of Diderot & d'Alembert - Collaborative Translation Project|access-date=April 1, 2015|date=2011-12-15}}</ref>

In most regions today, maize grown in residential [[garden]]s is still often planted manually with a [[hoe (tool)|hoe]], whereas maize grown commercially is no longer planted manually but rather is planted with a [[planter (farm implement)|planter]]. In North America, fields are often planted in a two-[[crop rotation]] with a [[Nitrogen fixation|nitrogen-fixing]] crop, often [[alfalfa]] in cooler climates and [[soybean]]s in regions with longer summers. Sometimes a third crop, [[winter wheat]], is added to the rotation.{{Citation needed|date=January 2021}}

Many of the maize varieties grown in the United States and Canada are hybrids. Often the varieties have been [[genetically modified]] to tolerate [[glyphosate]] or to provide protection against natural pests. Glyphosate is an herbicide which kills all plants except those with genetic tolerance. This genetic tolerance is very rarely found in nature.{{Citation needed|date=January 2021}}

In the midwestern United States, low-till or [[no-till farming]] techniques are usually used. In low-till, fields are covered once, maybe twice, with a tillage implement either ahead of crop planting or after the previous harvest. The fields are planted and [[anhydrous ammonia|fertilized]]. [[Weed]]s are controlled through the use of [[herbicide]]s, and no cultivation tillage is done during the growing season. This technique reduces moisture evaporation from the soil, and thus provides more moisture for the crop.
The technologies mentioned in the previous paragraph enable low-till and no-till farming. Weeds compete with the crop for moisture and nutrients, making them undesirable.{{Citation needed|date=January 2021}}

=== Harvesting ===
[[File:YellowCorn.jpg|thumb|left|Mature maize ears]]
[[File:Iowa harvest 2009.jpg|thumb|right|Harvesting maize, [[Jones County, Iowa]]]]
[[File:Maissipelto Rantasalmi.jpg|thumb|right|Harvesting maize, [[Rantasalmi, South Savonia]], Finland]]
[[File:MyanmarCorn3.jpg|thumb|right|Hand-picking harvest of maize in Myanmar]]

Maize harvested as a grain crop can be kept in the field a relatively long time, even months, after the crop is ready to harvest; it is also harvested and stored in the husk leaves if kept dry.<ref name="Wayne">{{Cite book|last1=Smith|first1=C. Wayne|url=https://books.google.com/books?id=eDJ3NjHh8H8C&pg=PA802|title=Corn: Origin, History, Technology, and Production|last2=Betrán|first2=Javier|last3=Runge|first3=Edward C. A.|date=2004-03-08|publisher=John Wiley & Sons|isbn=978-0-471-41184-0|language=en}}</ref> 
Before the 20th century, all maize harvesting was by [[manual labour]], by [[grazing]], or by some combination of those. Whether the ears were hand-picked and the [[corn stover|stover]] was grazed, or the whole plant was cut, gathered, and [[stook|shocked]], people and [[livestock]] did all the work. Between the 1890s and the 1970s, the technology of maize harvesting expanded greatly. Today, all such technologies, from entirely manual harvesting to entirely mechanized, are still in use to some degree, [[appropriate technology|as appropriate to each farm's needs]], although the thoroughly mechanized versions predominate, as they offer the lowest [[unit cost]]s when scaled to large farm operations.

Before [[World War II]], most maize in North America was harvested by hand. This involved a large number of workers and associated social events (husking or shucking [[communal work|bees]]). From the 1890s onward, some machinery became available to partially mechanize the processes, such as one- and two-row mechanical pickers (picking the ear, leaving the [[corn stover|stover]]) and corn binders, which are [[reaper-binder]]s designed specifically for maize. The latter produce [[sheaf (agriculture)|sheaves]] that can be [[stook|shocked]]. By hand or mechanical picker, the entire ear is harvested, which then requires a separate operation of a maize sheller to remove the kernels from the ear. Whole ears of maize were often stored in [[corn crib]]s, and these whole ears are a sufficient form for some livestock feeding use. Today corn cribs with whole ears, and corn binders, are less common because most modern farms harvest the grain from the field with a [[combine harvester|combine]] and store it in [[silo#Bins|bins]]. The combine with a corn head (with points and snap rolls instead of a reel) does not cut the stalk; it simply pulls the stalk down. The stalk continues downward and is crumpled into a mangled pile on the ground, where it usually is left to become [[organic matter]] for the [[soil]]. The ear of maize is too large to pass between slots in a plate as the snap rolls pull the stalk away, leaving only the ear and husk to enter the machinery. The combine separates the husk and the cob, keeping only the kernels.<ref>{{Cite book|last1=Brown|first1=Robert C.|url=https://books.google.com/books?id=SENOAgAAQBAJ&pg=PT114|title=Biorenewable Resources: Engineering New Products from Agriculture|last2=Brown|first2=Tristan R.|date=2013-12-06|publisher=Wiley|isbn=978-1-118-52492-3|language=en}}</ref>

The entire maize plant is also harvested as a [[silage]] crop.<ref>{{Cite web|title=Corn Silage Production and Management|url=https://extension.psu.edu/corn-silage-production-and-management|access-date=2021-11-14|publisher=Penn State Extension|language=en}}</ref>

For storing grain in bins, the moisture of the grain must be sufficiently low to avoid spoiling. If the moisture content of the harvested grain is too high, [[grain drying|grain dryers]] are used to reduce the moisture content by blowing heated air through the grain. This can require large amounts of energy in the form of combustible gases ([[propane]] or [[natural gas]]) and electricity to power the blowers.<ref>{{cite web|last=Van Devender|first=Karl|title=Grain Drying Concepts and Options|publisher=University of Arkansas Division of Agriculture|date=July 2011|url=http://www.uaex.edu/publications/pdf/FSA-1072.pdf|access-date=December 15, 2013}}</ref>

== Production ==
[[File:Production of maize (2019).svg|thumb|upright=1.35|Production of maize (2019)<ref>{{Cite book|url=https://doi.org/10.4060/cb4477en|title=World Food and Agriculture – Statistical Yearbook 2021|publisher=FAO|year=2021|isbn=978-92-5-134332-6|location=Rome|doi=10.4060/cb4477en|s2cid=240163091}}</ref>]]
Maize is widely cultivated throughout the world, and a greater weight of maize is produced each year than any other grain.<ref name=global>{{cite web|title=International Grains Council Market Report 28 November 2013|url=http://www.igc.int/downloads/gmrsummary/gmrsumme.pdf|author=International Grains Council (international organization)|year=2013|author-link=International Grains Council (international organization)}}</ref> In 2020, total world production was 1.16 billion [[tonne]]s, led by the United States with 31.0% of the total (table). China produced 22.4% of the global total.<ref name="fao.org">{{Cite web|url=http://www.fao.org/faostat/en/#data/QC|title=FAOSTAT|publisher=FAO}}</ref>

{{Infobox agricultural production 
| year               = 2020
|plant = Maize
| country1           = {{USA}}
| amount1            =360.3
| country2           ={{CHN}}
| amount2            =260.7
| country3           ={{BRA}}
| amount3            =104.0
| country4           ={{ARG}} 
| amount4            =58.4
| country5           ={{UKR}} 
| amount5            =30.3
| country6           ={{IND}} 
| amount6            =30.2
| country7           ={{MEX}} 
| amount7            =27.4
| country8           ={{IDN}} 
| amount8            =22.5
| country9           ={{ZAF}} 
| amount9            =15.3
| country10          ={{RUS}}  
| amount10           =13.9
| world              =1162.4
| source             = [[FAOSTAT]]<ref>{{cite web|title=Maize production in 2017, Crops/Regions/Production Quantity from pick lists|url=http://www.fao.org/faostat/en/#data/QC|publisher=United Nations, Food and Agriculture Organization, Statistics Division (FAOSTAT)|date=2018|access-date=15 March 2020}}</ref><ref name="fao.org"/>
}}

=== United States ===
{{Main|Corn production in the United States}}
In 2016, maize production was forecast to be over 380 million metric tons (15 billion [[bushel]]s), an increase of 11% over 2014 American production.<ref name="usda2016">{{cite web|title=Crop production, 2016|url=https://www.usda.gov/nass/PUBS/TODAYRPT/crop0816.pdf|publisher=US Department of Agriculture|access-date=4 April 2017|date=12 August 2016}}</ref> Based on conditions as of August 2016, the expected yield would be the highest ever for the United States.<ref name=usda2016 /> The area of harvested maize was forecast to be {{convert|87|e6acre|e6ha|order=flip|abbr=off}}, an increase of 7% over 2015.<ref name=usda2016 /> Maize is especially popular in [[Midwest United States|Midwestern]] states such as [[Indiana]], [[Iowa]], and [[Illinois]]; in the latter, it was named the state's official grain in 2017.<ref name="ill">{{cite web |url=http://www.chicagotribune.com/news/chicagoinc/ct-met-officially-corny-chicago-inc-20171228-story.html |title=Exciting days for corn lovers as corn to become official state grain of Illinois |work=[[Chicago Tribune]] |date=December 28, 2017 |last=Janssen |first=Kim}}</ref>

The estimated corn usage for crop year September 1, 2020 to August 31, 2021, was 38.7 percent was used for feed, 34 percent for ethanol, 17.5 percent for export, and 9.8 percent for food.<ref>{{cite news |last=Torban |first=Alli |url=https://www.axios.com/pandemic-corn-supply-chain-27e6175d-385d-444d-8675-175d496b9bf6.html?deepdive=1 |title=2. The pandemic wreaked havoc on the corn supply chain |work=[[Axios (website)|Axios]] |date=2021-12-04 |access-date=2021-12-07 }}</ref>

=== Trade ===
Corn futures are traded on several exchanges, the Chicago Board of Trade (CBOT) and JSE Derivatives (JDERIV). The Chicago Board Of Trade sells corn futures with a contact size of 5000 bushels which is quoted in cents/bushel and the JDERIV has a contact size of 100 Tonnes, quoted in Rand/Ton.<ref name="PortaraCQG">{{Cite web |title=Download Historical Corn Intraday Futures Data (CNA) |url=https://portaracqg.com/historical-futures-data/historical-corn-intraday-futures-data-cna/ |access-date=2022-05-17 |website=PortaraCQG |language=en-US}}</ref><ref name="PortaraCQG-2020">{{Cite web |title=Download Historical Chicago Corn - JSE Intraday Futures Data (CORN) |url=https://portaracqg.com/historical-futures-data/historical-chicago-corn-jse-intraday-futures-data-corn/ |access-date=2022-05-17 |website=PortaraCQG |date=May 24, 2020 |language=en-US}}</ref> The detailed contract specifications are listed below:
{| class="wikitable"
|+Contract Specifications<ref name="PortaraCQG" /><ref name="PortaraCQG-2020" />
!
!Corn (CORN)
!Corn (CNA)
|-
|Exchange: 
|JDERIV 
|CBOT
|-
|Sector: 
|Grain 
|Grain
|-
|Tick Size: 
|0.2 
|0.25
|-
|Tick Value: 
|5 ZAR 
|12.50 USD
|-
|BPV: 
|25
|50
|-
|Denomination: 
|[[South African rand|ZAR]]
|[[United States dollar|USD]]
|-
|Decimal Place: 
|1
|2
|}

==Pests==<!-- This section is linked from [[Transgenic maize]] -->

=== Insects ===
* [[African armyworm]] (''Spodoptera exempta'')
* [[Eldana|African sugarcane borer]] (''Eldana saccharina'')
* [[Asian corn borer]] (''Ostrinia furnacalis'')
* Common armyworm (''[[Pseudaletia unipuncta]]'')
* [[Common earwig]] (''Forficula auricularia'')
* [[Corn delphacid]] (''Peregrinus maidis'')
* [[Corn leaf aphid]] (''Rhopalosiphum maidis'')
* Corn rootworms (''[[Diabrotica]] spp'') including [[Western corn rootworm]] (''Diabrotica virgifera virgifera'' LeConte), Northern corn rootworm (''[[Diabrotica barberi|D. barberi]]'' or ''[[Diabrotica longicornis|D. longicornis]]'') and Southern corn rootworm (''[[Diabrotica undecimpunctata howardi|D. undecimpunctata howardi]]'')
* [[Euxesta stigmatias|Corn silkfly]] (''[[Euxesta stigmatias]]'')
* Dusky [[sap beetle]] (''[[Carpophilus lugubris]]'')
* [[European corn borer]] (''Ostrinia nubilalis'') (ECB)
* [[Fall armyworm]] (''Spodoptera frugiperda'') Some sweet corn varieties have developed partial resistance to fall army worms by producing a unique 33-kD proteinase that significantly retards fall army worm growth.<ref>{{Cite web|url=http://entnemdept.ufl.edu/creatures/field/fall_armyworm.htm|title=fall armyworm, Spodoptera frugiperda (J.E. Smith)|website=entnemdept.ufl.edu|access-date=2017-11-14}}</ref><ref>{{cite journal |last1=Pechan |first1=Tibor |last2=Ye |first2=Lijun |last3=Chang |first3=Yu-min |last4=Mitra |first4=Anurina |last5=Lin |first5=Lei |last6=Davis |first6=Frank M. |last7=Williams |first7=W. Paul |last8=Luthe |first8=Dawn S. |title=A Unique 33-kD Cysteine Proteinase Accumulates in Response to Larval Feeding in Maize Genotypes Resistant to Fall Armyworm and Other Lepidoptera |journal=[[The Plant Cell]]|date=July 2000 |volume=12 |issue=7 |pages=1031–1040 |doi=10.1105/tpc.12.7.1031 |pmid=10899972 |pmc=149047 }}</ref>
* Corn earworm/Cotton bollworm (''[[Helicoverpa zea]]'')
* [[Lesser cornstalk borer]] (''Elasmopalpus lignosellus'')
* [[Maize weevil]] (''Sitophilus zeamais'')
* Northern armyworm, Oriental armyworm or Rice ear-cutting caterpillar (''[[Mythimna separata]]'')
* [[Southwestern corn borer]] (''Diatraea grandiosella'')
* [[Stalk Borer|Stalk borer]] (''Papaipema nebris'')

The susceptibility of maize to the European corn borer and corn rootworms, and the resulting large crop losses which are estimated at a billion dollars worldwide for each pest,<ref>{{cite web |author=Marra, M.C. |author2=Piggott, N.E. |author3=Goodwin, B.K. |year=2012 |url=http://www.agbioforum.org/v15n2/v15n2a09-marra.htm |title=The impact of corn rootworm protected biotechnology traits in the United States |website=[[AgBioForum]] |volume=15 |issue=2 |pages=217–230 |access-date=October 6, 2013 |archive-date=August 6, 2016 |archive-url=https://web.archive.org/web/20160806035913/http://www.agbioforum.org/v15n2/v15n2a09-marra.htm |url-status=dead }}</ref><ref>Erin W. Hodgson, Utah State University Extension and Utah Plant Pest Diagnostic Laboratory. [http://extension.usu.edu/files/publications/factsheet/western-corn-rootworm.pdf Western corn rootworm]</ref><ref>Ostlie KR ''et al''. University of Minnesota Extension Office. Last Reviewed 2008. [http://www.extension.umn.edu/distribution/cropsystems/dc7055.html#ch1 Bt Corn & European Corn Borer: Long-Term Success Through Resistance Management] {{Webarchive|url=https://web.archive.org/web/20130928064604/http://www.extension.umn.edu/distribution/cropsystems/dc7055.html#ch1 |date=September 28, 2013}}</ref> led to the development of [[transgenic plants|transgenics]] expressing the ''[[Bacillus thuringiensis]]'' toxin. "Bt maize" is widely grown in the United States and has been approved for release in Europe.

=== Diseases ===
{{Main|List of maize diseases}}
* [[Rust (fungus)|Rust]]
* [[Corn smut]] or common smut (''Ustilago maydis''): a fungal disease, known in Mexico as ''huitlacoche'', which is prized by some as a gourmet delicacy in itself
* Northern corn leaf blight [http://www.extension.purdue.edu/extmedia/BP/BP-84-W.pdf (Purdue Extension site)] [https://www.pioneer.com/home/site/us/agronomy/crop-management/corn-insect-disease/northern-leaf-blight (Pioneer site)] {{Webarchive|url=https://web.archive.org/web/20170624094308/https://www.pioneer.com/home/site/us/agronomy/crop-management/corn-insect-disease/northern-leaf-blight |date=June 24, 2017 }}
* [[Southern corn leaf blight]]
* [[Maize downy mildew]] (''Peronosclerospora'' spp.)
* [[Maize dwarf mosaic virus]]
* [[Maize streak virus]]
* [[Stewart's wilt]] (''Pantoea stewartii'')
* Goss's wilt ([[Clavibacter michiganensis subsp. nebraskensis|''Clavibacter michiganensis'' subsp. ''nebraskensis'']])<ref name="Crop-Prot-Net">{{cite web |title=Goss's Wilt of Corn |website=[[Crop Protection Network]] |url=http://cropprotectionnetwork.org/resources/articles/diseases/gosss-wilt-of-corn |access-date=2021-07-15}}</ref>
* [[Grey leaf spot]]<ref name="Crous-Groenewald-Groenewald-Caldwell-2006" />
* [[Mal de Río Cuarto virus]] (MRCV)
* [[Stalk rot]]
* [[Ear rot]]
* ''[[Aspergillus flavus]]''<ref name="Ostry-et-al-2015" />
* ''[[Aspergillus parasiticus|A. parasiticus]]''<ref name="Ostry-et-al-2015" />

=== Storage ===
Drying is vital to prevent or at least reduce [[mycotoxin]] contamination. ''[[Aspergillus]]'' and ''[[Fusarium]]'' spp. are the most common mycotoxin sources, but there are others. Altogether maize contaminants are so common, and this crop is so economically important, that maize mycotoxins are among the most important in agriculture in general.<ref name="Ostry-et-al-2015">{{cite journal |last1=Ostrý |first1=Vladimír |last2=Malíř |first2=František |last3=Pfohl-Leszkowicz |first3=Annie |title=Comparative data concerning aflatoxin contents in Bt maize and non-Bt isogenic maize in relation to human and animal health – a review |journal=[[Acta Veterinaria Brno]]|date=2015 |volume=84 |issue=1 |pages=47–53 |doi=10.2754/avb201585010047 |doi-access=free }}</ref>

== Uses ==

=== Culinary{{anchor|Food}} ===
{{see|List of maize dishes}}
[[File:Summer corn (48286638996).jpg|thumb|Semi-peeled corn on the cob]]
[[File:Corn, the food of the nation, US Food Administration poster, 1918.jpg|left|thumb|upright|Poster showing a woman serving muffins, pancakes, and grits, with canisters on the table labeled corn meal, grits, and hominy, US Food Administration, 1918]]

Maize and [[cornmeal]] (ground dried maize) constitute a [[staple food]] in many regions of the world. Maize is used to produce [[cornstarch]], a common ingredient in home cooking and many industrialized food products. Maize starch can be [[hydrolysis|hydrolyzed]] and [[enzyme|enzymatically]] treated to produce syrups, particularly [[high fructose corn syrup]], a sweetener; and also fermented and distilled to produce [[grain alcohol]]. Grain alcohol from maize is traditionally the source of [[Bourbon whiskey]]. [[Cornmeal]] and [[maize flour]] are used to make [[cornbread]] and other baked products. Many countries require corn flour to be [[enriched flour|enriched]] with certain [[nutrient]]s.

In prehistoric times [[Mesoamerica]]n women used a ''[[metate]]'' to process maize into ground cornmeal, allowing the preparation of foods that were more calorie dense than popcorn. After ceramic vessels were invented the [[Olmec]] people began to cook maize together with beans, improving the nutritional value of the staple meal. Although maize naturally contains [[Niacin (nutrient)|niacin]], an important nutrient, it was not [[bioavailable]] without the process of [[nixtamalization]]. The [[Maya peoples|Maya]] used nixtamal meal to make varieties of porridges and tamales.<ref>{{cite book |author=Jeffrey M. Pilcher |title=Maize and the Making of Mexico |page=27}}</ref> The process was later used in the [[cuisine of the American South]] to prepare corn for [[grits]] and [[hominy]].{{Citation needed|date=January 2021}}

Maize is a staple of [[Mexican cuisine]]. [[Masa]] (cornmeal treated with [[limewater]]) is the main ingredient for [[tortilla]]s, [[atole]] and many other dishes of Central American food. It is the main ingredient of [[corn tortilla]], [[tamale]]s, [[pozole]], [[atole]] and all the dishes based on them, like [[taco]]s, [[quesadilla]]s, [[chilaquiles]], [[enchilada]]s, [[tostada (tortilla)|tostadas]] and many more. In Mexico the fungus of maize, known as [[huitlacoche]], is considered a delicacy.{{Citation needed|date=January 2021}}

[[File:ChiapasTamale2.JPG|thumb|Mexican [[tamales]] made with corn meal]]
[[File:Boiled corn on a white plate.jpg|thumb|Boiled corn on a white plate]]
Coarse maize meal is made into a thick [[porridge]] in many cultures: from the [[polenta]] of Italy, the ''angu'' of Brazil, the ''[[mămăligă]]'' of Romania, to [[Mush (cornmeal)|cornmeal mush]] in the US (or [[hominy]] [[grits]] in the South) or the food called [[mieliepap]] in South Africa and sadza, nshima, ugali and other names in other parts of Africa. Introduced into Africa by the Portuguese in the 16th century, maize has become Africa's most important staple food crop.<ref>"[http://www.fao.org/docrep/009/a0154e/A0154E02.HTM The cassava transformation in Africa]". The Food and Agriculture Organization of the United Nations (FAO).</ref> These are commonly eaten in the [[Southeastern United States]], foods handed down from [[Native Americans in the United States|Native Americans]], who called the dish [[sagamite]].{{Citation needed|date=January 2021}}

Maize can also be harvested and consumed in the unripe state, when the kernels are fully grown but still soft. Unripe maize must usually be cooked to become palatable; this may be done by simply boiling or roasting the whole ears and eating the kernels right off the cob. [[Sweet corn]], a genetic variety that is high in sugars and low in starch, is usually consumed in the unripe state. Such [[corn on the cob]] is a common dish in the United States, Canada, United Kingdom, Cyprus, some parts of South America, and the Balkans, but virtually unheard of in some European countries.{{citation needed|date=May 2020}} Corn on the cob was hawked on the streets of early 19th-century New York City by poor, barefoot "[[Hot Corn]] Girls", who were thus the precursors of [[hot dog cart]]s, [[churro]] wagons, and fruit stands seen on the streets of big cities today.<ref>Solon Robinson. Hot Corn: Life Scenes in New York Illustrated (Series appearing in 1853 in the NY Tribune, later as a book)</ref>

Within the United States, the usage of maize for human consumption constitutes only around 1/40th of the amount grown in the country. In the United States and Canada, maize is mostly grown to feed [[livestock]], as forage, [[silage]] (made by fermentation of chopped green cornstalks), or grain. Maize meal is also a significant ingredient of some commercial animal food products.{{Citation needed|date=January 2021}}

=== Nutritional value ===
{{nutritionalvalue
| name = Sweetcorn, yellow, raw<br />(seeds only)<br /><sub>''Note: assuming [[nixtamalization|freed]] niacin''</sub>
| kJ = 360
| water = 75.96 g
| protein = 3.27 g
| fat = 1.35 g
| carbs = 18.7 g
| fiber = 2 g
| sugars = 6.26 g
| starch = 5.7 g
| iron_mg = 0.52
| magnesium_mg = 37
| phosphorus_mg = 89
| potassium_mg = 270
| zinc_mg = 0.46
| manganese_mg = 0.163
| vitC_mg = 6.8
| thiamin_mg = 0.155
| riboflavin_mg = 0.055
| niacin_mg = 1.77
| pantothenic_mg = 0.717
| folate_ug = 42
| vitB6_mg = 0.093
| vitA_ug = 9
| lutein_ug = 644
| tryptophan = 0.023 g
| threonine = 0.129 g
| isoleucine = 0.129 g
| leucine = 0.348 g
| lysine = 0.137 g
| methionine = 0.067 g
| cystine = 0.026 g
| phenylalanine = 0.150 g
| tyrosine = 0.123 g
| valine = 0.185 g
| arginine = 0.131 g
| histidine = 0.089 g
| alanine = 0.295 g
| aspartic acid = 0.244 g
| glutamic acid = 0.636 g
| glycine = 0.127 g
| proline = 0.292 g
| serine = 0.153 g
| source_usda = 1
| note = [https://fdc.nal.usda.gov/fdc-app.html#/food-details/169998/nutrients Link to USDA Database entry]<br />One ear of medium size (6-3/4" to 7-1/2" long)<br />maize has 90 grams of seeds
}}

Raw, yellow, sweet maize kernels are composed of 76% water, 19% [[carbohydrates]], 3% [[protein]], and 1% [[fat]] (table). In a 100-[[gram]] serving, maize kernels provide 86 [[calories]] and are a good source (10–19% of the [[Daily Value]]) of the [[B vitamins]], [[thiamin]], [[Niacin (nutrient)|niacin]] (but see [[#Pellagra|Pellagra warning]] below), [[pantothenic acid]] (B5) and [[folate]] (right table for raw, uncooked kernels, [[USDA]] Nutrient Database). In moderate amounts, they also supply [[dietary fiber]] and the [[essential minerals]], [[magnesium]] and [[phosphorus]] whereas other nutrients are in low amounts (table).{{Citation needed|date=January 2021}}

Maize has suboptimal amounts of the [[essential amino acid]]s [[tryptophan]] and [[lysine]], which accounts for its lower status as a protein source.<ref name="UNFAO-1992">{{cite web|url=http://www.fao.org/docrep/t0395e/T0395E0c.htm|title=Chapter 8: Improvement of maize diets; from corporate document: Maize in human nutrition|publisher=United Nations Food and Agriculture Organization|date=1992|access-date=5 June 2017}}</ref> However, the proteins of beans and legumes complement those of maize.<ref name="UNFAO-1992" />

=== Feed and fodder for livestock ===
{{See also|Corn stover#Uses}}
Maize is a major source of both grain [[animal feed|feed]] and [[fodder]] for [[livestock]]. It is fed to the livestock in various ways. When it is used as a grain crop, the dried [[corn kernel|kernels]] are used as feed. They are often kept on the [[corncob|cob]] for storage in a [[corn crib]], or they may be shelled off for storage in a [[grain bin]]. The farm that consumes the feed may produce it, purchase it on the market, or some of both. When the grain is used for feed, the rest of the plant (the [[corn stover]]) can be used later as fodder, [[bedding (animals)|bedding]] (litter), or [[soil conditioner|soil amendment]]. When the whole maize plant (grain plus stalks and leaves) is used for fodder, it is usually [[forage harvester|chopped all at once]] and [[silage|ensilaged]], as digestibility and palatability are higher in the ensilaged form than in the dried form. Maize silage is one of the most valuable forages for ruminants.<ref>Heuzé V., Tran G., Edouard N., Lebas F., 2017. Maize silage. Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. https://www.feedipedia.org/node/13883 Last updated on June 22, 2017, 14:24</ref> Before the advent of widespread ensilaging, it was traditional to gather the corn into [[stook|shocks]] after harvesting, where it dried further. With or without a subsequent move to the cover of a barn, it was then stored for weeks to several months until fed to the livestock. Today ensilaging can occur not only in [[silo]]es but also in silage wrappers. However, in the tropics, maize can be harvested year-round and fed as green forage to the animals.<ref>Heuzé V., Tran G., Edouard N., Lebas F., 2017. Maize green forage. Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. https://www.feedipedia.org/node/358 Last updated on June 21, 2017, 10:16</ref>

=== Chemicals ===
Starch from maize can also be made into [[plastics]], [[fabric]]s, [[adhesive]]s, and many other chemical products.{{Citation needed|date=January 2021}}

The [[corn steep liquor]], a plentiful watery byproduct of maize [[wet milling]] process, is widely used in the [[biochemistry|biochemical industry]] and research as a culture medium to grow many kinds of [[microorganism]]s.<ref name=a>{{cite journal|journal=[[Bacteriological Reviews]]|date=December 1948|volume=12|issue=4|pages=297–311|title=Corn steep liquor in microbiology|first1=R. Winston|last1=Liggett|first2=H.|last2=Koffler |pmc=180696 |pmid=16350125|doi=10.1128/MMBR.12.4.297-311.1948}}</ref>

[[Chrysanthemin]] is found in [[purple corn]] and is used as a food coloring.{{Citation needed|date=January 2021}}

=== Bio-fuel ===
{{See also|Corn ethanol|Corn stover}}
"Feed maize" is being used increasingly for heating;<ref>{{Cite news|url=http://news.nationalgeographic.com/news/energy/2015/03/150301-corn-stoves/|title=Corn for Home Heat: A Green Idea That Never Quite Popped|date=2015-03-02|access-date=2017-07-07}}</ref> specialized [[pellet stove|corn stoves]] (similar to [[wood fuel|wood stoves]]) are available and use either feed maize or wood pellets to generate heat. Maize cobs are also used as a [[biomass]] fuel source. Maize is relatively cheap and home-heating furnaces have been developed which use maize kernels as a fuel. They feature a large hopper that feeds the uniformly sized maize kernels (or wood pellets or [[cherry]] pits) into the fire.{{Citation needed|date=January 2021}}

Maize is increasingly used as a feedstock for the production of [[ethanol fuel]].<ref>{{cite journal |last1=Torres |first1=Andres F. |last2=Slegers |first2=Petronella M. |last3=Noordam-Boot |first3=Cornelie M. M. |last4=Dolstra |first4=Oene |last5=Vlaswinkel |first5=Louis |last6=van Boxtel |first6=Anton J. B. |last7=Visser |first7=Richard G. F. |last8=Trindade |first8=Luisa M. |title=Maize feedstocks with improved digestibility reduce the costs and environmental impacts of biomass pretreatment and saccharification |journal=[[Biotechnology for Biofuels]]|date=December 2016 |volume=9 |issue=1 |pages=63 |doi=10.1186/s13068-016-0479-0 |pmc=4791978 |pmid=26981155 |doi-access=free }}</ref> When considering where to construct an ethanol plant, one of the site selection criteria is to ensure there is locally available feedstock.<ref>{{Cite news|url=https://thermalkinetics.net/products/fuel-ethanol-plants/|title=Fuel Ethanol Plants – Thermal Kinetics Engineering, PLLC|work=Thermal Kinetics Engineering, PLLC|access-date=2017-07-07|language=en-US}}</ref> Ethanol is mixed with gasoline to decrease the amount of pollutants emitted when used to fuel motor vehicles. High fuel prices in mid-2007 led to higher demand for ethanol, which in turn led to higher prices paid to farmers for maize. This led to the 2007 harvest being one of the most profitable maize crops in modern history for farmers. Because of the relationship between fuel and maize, prices paid for the crop now tend to track the price of oil. {{Citation needed|date=December 2009}}

The price of food is affected to a certain degree by the use of maize for biofuel production. The cost of transportation, production, and marketing are a large portion (80%) of the price of food in the United States. Higher energy costs affect these costs, especially transportation. The increase in [[food prices]] the consumer has been seeing is mainly due to the higher energy cost. The effect of biofuel production on other food crop prices is indirect. Use of maize for biofuel production increases the demand, and therefore price of maize. This, in turn, results in farm acreage being diverted from other food crops to maize production. This reduces the supply of the other food crops and increases their prices.<ref>{{cite news|url=http://www.csmonitor.com/Money/2008/0128/p03s03-usec.html|title=Christian Science Monitor|newspaper=[[Christian Science Monitor]]|author=Mark Clayton|date=January 28, 2008|access-date=October 6, 2014}}</ref><ref>{{cite web|url=http://www.iowarfa.org/food_facts.php |title=Iowa Renewable Fuels Association |access-date=October 6, 2014 |url-status=dead |archive-url=https://web.archive.org/web/20141011043043/http://www.iowarfa.org/food_facts.php |archive-date=October 11, 2014 }}</ref>

[[File:Haase anaerobic digester.JPG|left|thumb|Farm-based maize silage digester located near [[Neumünster]] in Germany, 2007. The green tarpaulin top cover is held up by the biogas stored in the digester.]]

Maize is widely used in Germany as a feedstock for [[anaerobic digesters|biogas plants]]. Here the maize is harvested, shredded then placed in [[silage]] clamps from which it is fed into the biogas plants. This process makes use of the whole plant rather than simply using the kernels as in the production of fuel ethanol.{{Citation needed|date=January 2021}}

A [[biomass gasification]] power plant in Strem near [[Güssing]], [[Burgenland]], Austria, began in 2005. There is potential that [[Diesel fuel|diesel]] can be created from the biogas by the [[Fischer Tropsch]] method.<ref>{{Cite web |last1=Hermann |first1=Hofbauer |last2=Reinhard |first2=R. |last3=Klaus |first3=Bosch |last4=Reinhard |first4=K. |last5=Christian |first5=Aichernig |date=January 2002 |title=Biomass CHP plant Güssing - A success story |url=https://www.researchgate.net/publication/242422623 |publisher=Ministry of Economy and Labour and of the Federal States of Niederösterreich and Burgenland|s2cid=56073239}}</ref>

Increasingly, ethanol is being used at low concentrations (10% or less) as an additive in [[gasoline]] ([[gasohol]]) for motor fuels to increase the [[octane rating]], lower pollutants, and reduce petroleum use (what is nowadays also known as "[[biofuels]]" and has been generating an intense debate regarding the human beings' necessity of new sources of energy, on the one hand, and the need to maintain, in regions such as Latin America, the food habits and culture which has been the essence of civilizations such as the one originated in Mesoamerica; the entry, January 2008, of maize among the commercial agreements of [[North American Free Trade Agreement|NAFTA]] has increased this debate, considering the bad labor conditions of workers in the fields, and mainly the fact that NAFTA "opened the doors to the import of maize from the United States, where the farmers who grow it receive multimillion-dollar subsidies and other government supports. ... According to OXFAM UK, after NAFTA went into effect, the price of maize in Mexico fell 70% between 1994 and 2001. The number of farm jobs dropped as well: from 8.1 million in 1993 to 6.8 million in 2002. Many of those who found themselves without work were small-scale maize growers.").<ref>{{Cite web|url=https://www.envio.org.ni/articulo/2676|title=Revista Envío - Are Free Trade Agreements Free? Are They Development Strategies?|website=envio.org.ni}}</ref> However, introduction in the northern latitudes of the US of [http://www.aces.uiuc.edu/news/stories/news4169.html tropical maize for biofuels], and not for human or animal consumption, may potentially alleviate this.{{Citation needed|date=January 2021}}

=== Commodity ===
Maize is bought and sold by investors and price speculators as a tradable commodity using corn [[futures contract]]s. These "futures" are traded on the [[Chicago Board of Trade]] (CBOT) under [[ticker symbol]] '''C'''. They are delivered every year in March, May, July, September, and December.<ref>[[wikinvest:Corn Prices|CBOT Corn Futures Contract Overview via Wikinvest]]</ref>

=== Ornamental and other uses ===
{{Main|Corn construction}}
Some forms of the plant are occasionally grown for ornamental use in the garden. For this purpose, variegated and colored leaf forms as well as those with colorful ears are used.{{Citation needed|date=January 2021}}

Corncobs can be hollowed out and treated to make inexpensive [[smoking pipe (tobacco)|smoking pipes]], first manufactured in the United States in 1869.{{Citation needed|date=January 2021}}

[[File:CornKernelBox.jpg|thumb|right|Children playing in a maize kernel box]]
An unusual use for maize is to create a "[[corn maze]]" (or "maize maze") as a tourist attraction. The idea of a maize maze was introduced by the American Maze Company who created a maze in [[Pennsylvania]] in 1993.<ref>[http://www.americanmaze.com/about-the-american-maze/#first About the American Maze], The American Maze Company</ref>{{Better source needed|date=January 2021}} Traditional mazes are most commonly grown using [[taxus|yew]] [[hedge (gardening)|hedges]], but these take several years to mature. The rapid growth of a field of maize allows a maze to be laid out using [[Global Positioning System|GPS]] at the start of a growing season and for the maize to grow tall enough to obstruct a visitor's line of sight by the start of the summer. In Canada and the US, these are popular in many farming communities.{{Citation needed|date=January 2021}}

Maize kernels can be used in place of sand in a [[sandpit|sandboxlike]] enclosure for children's play.<ref name=corn_box>{{cite web |url=http://www.mazefunpark.com/attractions/details.php?attraction_id=5 |title=Maize Quest Fun Park: Corn Box |access-date=October 8, 2007 |url-status=dead |archive-url=https://web.archive.org/web/20071012201617/http://mazefunpark.com/attractions/details.php?attraction_id=5 |archive-date=October 12, 2007 |df=mdy-all}}</ref>

Stigmas from female maize flowers, popularly called [[corn silk]], are sold as [[herbalism|herbal supplements]].{{citation needed|date=September 2014}}

Maize is used as a [[Bait (luring substance)|fish bait]], called "dough balls". It is particularly popular in Europe for [[coarse fishing]].{{Citation needed|date=January 2021}}

Additionally, feed corn is sometimes used by hunters to bait animals such as deer or wild hogs.{{Citation needed|date=January 2021}}

=== United States usage breakdown ===

The breakdown of usage of the 12.1-billion-[[bushel]] <!-- taking 1 bu=25.4012 kg -->(307-million-tonne) 2008 US maize crop was as follows, according to the World Agricultural Supply and Demand Estimates Report by the USDA.<ref>{{cite web |url=http://www.iowacorn.org/User/Docs/2009_US_Corn_Stats.pdf |title=2009 US Corn Stats |publisher=Iowa Corn |access-date=December 2, 2010}}</ref>

{|class=wikitable
|-
!rowspan=2|Use
!colspan=3|Amount
|-
!million bushels
!million tonnes
!percentage
|-
|livestock feed
|style="text-align:right"|5,250
|style="text-align:right"|133.4
|style="text-align:right"|43.4
|-
|[[ethanol fuel|ethanol]] production
|style="text-align:right"|3,650
|style="text-align:right"|92.7
|style="text-align:right"|30.2
|-
|exports
|style="text-align:right"|1,850
|style="text-align:right"|47.0
|style="text-align:right"|15.3
|-
|production of starch, corn oil, sweeteners ([[High-fructose corn syrup|HFCS]], etc.)
|style="text-align:right"|943
|style="text-align:right"|24.0
|style="text-align:right"|7.8
|-
|human consumption—grits, corn flour, corn meal, beverage alcohol
|style="text-align:right"|327
|style="text-align:right"|8.3
|style="text-align:right"|2.7
|}

In the US since 2009/2010, maize feedstock use for ethanol production has somewhat exceeded direct use for livestock feed; maize use for fuel ethanol was 5,130 million bushels (130 million tonnes) in the 2013/2014 marketing year.<ref>United States Department of Agriculture, Economic Research Service. Corn supply, disappearance, and share of total corn used for ethanol. www.ers.usda.gov/datafiles/US_Bioenergy/Feedstocks/table05.xls (Excel file, accessed June 29, 2015).</ref>

A fraction of the maize feedstock dry matter used for ethanol production is usefully recovered as DDGS (dried distillers grains with solubles). In the 2010/2011 marketing year, about 29.1 million tonnes of DDGS were fed to US livestock and poultry.<ref name=Hoffman2011>Hoffman, L. and A. Baker. 2011. Estimating the substitution of distillers'grains for corn and soybean meal in the U.S. feed complex. United States Department of Agriculture, Economic Research Service. FDS-11-l-01. 62 pp.</ref> Because starch utilization in fermentation for ethanol production leaves other grain constituents more concentrated in the residue, the feed value per kg of DDGS, with regard to ruminant-metabolizable energy and protein, exceeds that of the grain. Feed value for monogastric animals, such as swine and poultry, is somewhat lower than for ruminants.<ref name=Hoffman2011 />

== Comparison to other staple foods ==
{{Nutrient contents of common foods}}
The following table shows the nutrient content of maize and major staple foods in a raw harvested form on a [[Dry matter#Dry matter basis|dry weight basis]] to account for their different water contents. Raw forms are not usually eaten and cannot be digested well. They are either sprouted, or prepared and cooked for human consumption. In sprouted or cooked form, the nutritional and anti-nutritional contents of each of these staples differ from that of raw form of these staples reported in the table below.

{{center|<sub>'''''Note: niacin for maize assumes [[nixtamalization|freed]] niacin.'''''</sub>}}
{{Comparison of major staple foods}}

== Hazards ==

=== Pellagra ===
{{Main|Pellagra}}
When maize was first introduced into farming systems other than those used by traditional native-American peoples, it was generally welcomed with enthusiasm for its productivity. However, a widespread problem of malnutrition soon arose wherever maize was introduced as a [[staple food]]. This was a mystery, since these types of malnutrition were not normally seen among the indigenous Americans, for whom maize was the principal staple food.<ref name=pellagra_mystery>{{cite web|url=http://www.eufic.org/web/article.asp?cust=1&lng=en&sid=4&did=16&artid=103 |title=The origins of maize: the puzzle of pellagra |access-date=September 14, 2006 |work=EUFIC > Nutrition > Understanding Food |date=December 2001 |publisher=The European Food Information Council |url-status=dead |archive-url=https://web.archive.org/web/20060927074332/http://www.eufic.org/web/article.asp?cust=1&lng=en&sid=4&did=16&artid=103 |archive-date=September 27, 2006 }}</ref>

It was eventually discovered that the indigenous Americans had learned to soak maize in [[alkali]] — water (the process now known as [[nixtamalization]]) — made with ashes and lime ([[calcium oxide]]) since at least 1200–1500 BC by [[Mesoamericans]]. They did this to liberate the corn hulls, but (unbeknownst to natives or colonists) it coincidentally liberates the B-vitamin [[Niacin (nutrient)|niacin]], the lack of which was the underlying cause of the condition known as [[pellagra]].<ref name="StallerCarrasco2009">{{cite book|first1=John |last1=Staller|first2=Michael
|last2= Carrasco|title=Pre-Columbian Foodways: Interdisciplinary Approaches to Food, Culture, and Markets in Ancient Mesoamerica|url={{google books |plainurl=y |id=FJrr9i6HRp0C|page=317}}|date=24 November 2009|publisher=Springer Science & Business Media|page=317|isbn=978-1-4419-0471-3}}</ref>

Maize was introduced into the diet of non-indigenous Americans without the necessary cultural knowledge historically acquired in the Americas. In the late 19th century, pellagra reached epidemic proportions in parts of the southern US, as medical researchers debated two theories for its origin: the deficiency theory (which was eventually shown to be true) said that pellagra was due to a deficiency of some nutrient, and the germ theory said that pellagra was caused by a germ transmitted by stable flies. Another theory promoted by the eugenicist [[Charles Davenport]] held that people only contracted pellagra if they were susceptible to it due to certain "constitutional, inheritable" traits of the affected individual.<ref name="Chase1980">{{cite book|first=Allan |last=Chase|title=The Legacy of Malthus: the social costs of the new scientific racism|url={{google books |plainurl=y |id=VDQFAQAAIAAJ}}|date=April 1980|publisher=University of Illinois Press|isbn=978-0-252-00790-3}} [http://crcrth645.wikispaces.umb.edu/pellagra Precis by Jan Coe]</ref>

Once alkali processing and dietary variety were understood and applied, pellagra disappeared in the developed world. The development of high lysine maize and the promotion of a more balanced diet have also contributed to its demise. Pellagra still exists today in food-poor areas and refugee camps where people survive on donated maize.<ref name="Thompson2016">{{cite book|first1=Janice J. |last1=Thompson|first2=Melinda|last2=Manore|first3=Linda |last3=Vaughan|title=The Science of Nutrition|chapter-url={{google books |plainurl=y |id=pbd5CwAAQBAJ|page=292}}|date=15 January 2016|publisher=Pearson Education |isbn=978-0-13-429880-1|chapter=Nutrients involved in energy metabolism |pages=292–321}} Also {{ISBN|978-0-321-64316-2}}.</ref>

=== Allergy ===
{{Main|Corn allergy}}
Maize contains [[Lipid transfer proteins|lipid transfer protein]], an indigestible protein that survives cooking. This protein has been linked to a rare and understudied [[allergy]] to maize in humans.<ref>[http://foodallergens.ifr.ac.uk/food.lasso?selected_food=33#summary Corn (maize) Allergy] {{Webarchive|url=https://web.archive.org/web/20080930153724/http://foodallergens.ifr.ac.uk/food.lasso?selected_food=33#summary |date=September 30, 2008}}, InformAll Database, October 18, 2006</ref> The allergic reaction can cause skin rash, swelling or itching of [[mucous membranes]], diarrhea, vomiting, [[asthma]] and, in severe cases, [[anaphylaxis]]. It is unclear how common this allergy is in the general population.{{Citation needed|date=January 2021}}

The ''Z. mays'' plant has an [[OPALS (Ogren Plant Allergy Scale)|OPALS allergy scale]] rating of 5 out of 10, indicating moderate potential to cause allergic reactions, exacerbated by over-use of the same plant throughout a garden. Corn pollen is heavy, large, and usually airborne in the early morning.<ref name="Ogren">{{cite book|last=Ogren|first=Thomas Leo|title=The Allergy-Fighting Garden|date=2015|publisher=Ten Speed Press|location=Berkeley|isbn=9781607744917}}</ref>

=== Mycotoxins ===
[[Fungicide application]] does not reduce fungal growth or mycotoxin dramatically, although it can be a part of a successful reduction strategy. Among the most common toxins are those produced by ''[[Aspergillus]]'' and ''[[Fusarium]]'' spp. The most common toxins are [[aflatoxin]]s, [[fumonisin]]s, [[zearalenone]], and [[ochratoxin A]]. [[Bt maize]] discourages insect vectors and by so doing it dramatically reduces concentrations of fumonisins, significantly reduces aflatoxins, but only mildly reduces others.<ref name="Ostry-et-al-2015" />

== Art ==
{{multiple image
 | align = right
 | direction = horizontal
 | image1 = Mochica Corn.jpg
 | width1 = 175
 | caption1 = Gold maize. Moche culture 300 A.D., [[Larco Museum]], [[Lima]], Peru
 | image2 = CornWaterTower.JPG
 | width2 = 150
 | caption2 = [[Water tower]] in [[Rochester, Minnesota]] being painted as an ear of maize
}}
Maize has been an essential crop in the [[Andes]] since the [[pre-Columbian era]]. The [[Moche culture|Moche]] culture from Northern Peru made ceramics from earth, water, and fire. This pottery was a sacred substance, formed in significant shapes and used to represent important themes. Maize was represented anthropomorphically as well as naturally.<ref>Berrin, Katherine & [[Larco Museum]]. The Spirit of Ancient Peru: Treasures from the Museo Arqueológico Rafael Larco Herrera. New York: Thames and Hudson, 1997.</ref>

In the United States, maize ears along with tobacco leaves are carved into the capitals of columns in the [[United States Capitol]] building. Maize itself is sometimes used for temporary architectural detailing when the intent is to celebrate the fall season, local agricultural productivity and culture. Bundles of dried maize stalks are often displayed along with pumpkins, gourds and straw in autumnal displays outside homes and businesses. A well-known example of architectural use is the [[Corn Palace]] in Mitchell, South Dakota, which uses cobs and ears of colored maize to implement a mural design that is recycled annually. Another well-known example is the ''[[Field of Corn]]'' sculpture in [[Dublin, Ohio]], where hundreds of concrete ears of corn stand in a grassy field.<ref>{{cite web |title=From oddity to cherished Dublin icon, 'Field of Corn' celebrates 25 years |last=Gordon |first=Ken |url=https://www.dispatch.com/news/20190928/from-oddity-to-cherished-dublin-icon-field-of-corn-celebrates-25-years |date=September 28, 2019 |work=[[The Columbus Dispatch]] |archive-url=https://web.archive.org/web/20190930070612/https://www.dispatch.com/news/20190928/from-oddity-to-cherished-dublin-icon-field-of-corn-celebrates-25-years |archive-date=September 30, 2019 |access-date=December 21, 2021}}</ref>

A maize stalk with two ripe ears is depicted on the [[Obverse and reverse|reverse]] of the Croatian 1 [[Croatian kuna|lipa]] coin, minted since 1993.<ref>[http://www.hnb.hr/ Croatian National Bank]. [http://www.hnb.hr/novcan/ekovanic.htm?tsfsg=a89719a221b101407a7b882421d5f621 Kuna and Lipa, Coins of Croatia] {{webarchive|url=https://web.archive.org/web/20090622012116/http://www.hnb.hr/novcan/ekovanic.htm?tsfsg=a89719a221b101407a7b882421d5f621 |date=June 22, 2009}}: [http://www.hnb.hr/novcan/kovanice/e1lipa.htm?tsfsg=dd58a2499ab048a6770b27c3017b7ec2 1 Lipa Coin] {{webarchive|url=https://web.archive.org/web/20110628203927/http://www.hnb.hr/novcan/kovanice/e1lipa.htm?tsfsg=dd58a2499ab048a6770b27c3017b7ec2 |date=June 28, 2011}}. Retrieved on March 31, 2009.</ref>

''[[Shucked]]'', a 2022 musical that is currently running on [[Broadway theatre|Broadway]], was described by [[Vulture (website)|''Vulture'']] as a "show about corn". Much of the show contains puns relating to corn<ref>{{Cite web |last=Alter |first=Rebecca |date=2023-04-05 |title=What the Shuck Is Happening to Broadway? |url=https://www.vulture.com/article/shucked-broadway-musical-fans-scene-report.html |access-date=2023-08-14 |website=Vulture |language=en-us}}</ref><ref>{{Cite news |last=Horton |first=Adrian |date=2023-04-05 |title=Shucked review – corny musical brings country to Broadway |language=en-GB |work=The Guardian |url=https://www.theguardian.com/stage/2023/apr/04/shucked-review-corny-musical-broadway |access-date=2023-08-14 |issn=0261-3077}}</ref> and the plot revolves around a [[Blight|blighted]] corn crop.<ref>{{Cite web |last=Cote |first=David |date=2023-04-05 |title=Review: "Shucked" Pops Loudly on Broadway, Despite Some Empty Calories |url=https://observer.com/2023/04/review-shucked-pops-loudly-on-broadway-despite-some-empty-calories/ |access-date=2023-08-14 |website=Observer |language=en-US}}</ref>  

== See also ==
{{Portal|Food|Agriculture and Agronomy}}
{{div col|colwidth=20em}}
* [[Blue corn]]
* [[Purple corn]]
* [[Columbian Exchange]]
* [[Corn syrup]]
* [[Crop circle]]
* [[Detasseling]]
* [[List of maize dishes]]
* [[List of sweetcorn varieties]]
* [[Post-harvest losses (grains)]]
* [[Push–pull technology]], pest control strategy for maize and [[sorghum]]
* [[Zein]]
{{div col end}}
{{clear}}

== References ==
{{Reflist|refs=

<ref name="Crous-Groenewald-Groenewald-Caldwell-2006">{{cite journal |last1=Crous |first1=Pedro W. |last2=Groenewald |first2=Johannes Z. |last3=Groenewald |first3=Marizeth |last4=Caldwell |first4=Pat |last5=Braun |first5=Uwe |last6=Harrington |first6=Thomas C. |title=Species of ''Cercospora'' associated with grey leaf spot of maize |journal=[[Studies in Mycology]]|publisher=[[Elsevier]]|volume=55 |date=1 May 2006 |pmid=18490979 |doi=10.3114/sim.55.1.189 |pmc=2104713 |pages=189–197 |s2cid=31494639|id=[[Westerdijk Institute]]}}</ref>

}}

== Further reading ==
* {{cite book|author1=Aureliano Brandolni|author2=Andrea Brandolini|title=Il mais in Italia: storia naturale e agricola|quote=XII+370 pages and 80 colour pages|publisher=CRF press|location=Bergamo, Italy|year=2006|url=http://www.asa-press.com/l-mais.html|access-date=March 14, 2009|archive-url=https://web.archive.org/web/20090531045824/http://www.asa-press.com/l-mais.html|archive-date=May 31, 2009|url-status=dead|df=mdy-all}}
* Byerlee, Derek. "The globalization of hybrid maize, 1921–70." ''[[Journal of Global History]]'' 15.1 (2020): 101–122.
* Clampitt, Cynthia. ''Maize: How Corn Shaped the U.S. Heartland'' (2015)
* {{cite web|author1=Ferro, D.N. |author2=Weber, D.C. |name-list-style=amp |url=http://www.eap.mcgill.ca/CPMP_1.htm|title=Managing Sweet Corn Pests in Massachusetts}}
* {{cite book|first=Duccio |last=Bonavia|title=Maize: Origin, Domestication, and Its Role in the Development of Culture|url={{google books |plainurl=y |id=TciIlddPBasC}}|date=13 May 2013|publisher=Cambridge University Press|isbn=978-1-107-02303-1}}

== External links ==
{{Commons}}
{{Wikispecies|Zea mays|''Zea mays''}}
* [http://www.maizegdb.org/ Maize Genetics and Genomics Database]
* [http://maizecoop.cropsci.uiuc.edu/ Maize Genetics Cooperation Stock Center]
* {{GRIN}}
* {{Cite NIE|wstitle=Maize|short=x}}
*''[https://youtube.com/watch?v=GP-lWN0uopM Corn: "The Outer Limits"]'', ca. 1976, Archives of Ontario YouTube Channel

{{corn}}
{{Cereals}}
{{Agriculture country lists}}
{{Model Organisms}}
{{Bioenergy}}
{{Taxonbar|from=Q11575}}
{{Authority control}}

[[:Category:Maize| ]]
[[:Category:Zea (plant)]]
[[:Category:Agriculture in Mesoamerica]]
[[:Category:Crops originating from Mexico]]
[[:Category:Demulcents]]
[[:Category:Energy crops]]
[[:Category:Flora of Guatemala]]
[[:Category:Flora of Mexico]]
[[:Category:Fruit vegetables]]
[[:Category:Grasses of Mexico]]
[[:Category:Plant models]]
[[:Category:Pre-Columbian Native American cuisine]]
[[:Category:Post-Columbian Native American cuisine]]
[[:Category:Pre-Columbian Southwest cuisine]]
[[:Category:Staple foods]]
[[:Category:Tropical agriculture]]
[[:Category:Plants described in 1753]]
[[:Category:Symbols of Illinois]]
<ref>https://en.wikipedia.org/wiki/Maize
</ref>