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Maize (''Zea mays''), also known as corn in
North American North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Ca ...
and
Australian Australian(s) may refer to: Australia * Australia, a country * Australians, citizens of the Commonwealth of Australia ** European Australians ** Anglo-Celtic Australians, Australians descended principally from British colonists ** Aboriginal Au ...
English, is a tall stout
grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...
that produces
cereal grain A cereal is any grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grain crops are grown in greater quantities and provide more food en ...
. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild
teosinte ''Zea'' is a genus of flowering plants in the grass family. The best-known species is ''Z. mays'' (variously called maize, corn, or Indian corn), one of the most important crops for human societies throughout much of the world. The four wild sp ...
. Native Americans planted it alongside
bean A bean is the seed of several plants in the family Fabaceae, which are used as vegetables for human or animal food. They can be cooked in many different ways, including boiling, frying, and baking, and are used in many traditional dishes th ...
s and
squash Squash may refer to: Sports * Squash (sport), the high-speed racquet sport also known as squash racquets * Squash (professional wrestling), an extremely one-sided match in professional wrestling * Squash tennis, a game similar to squash but pla ...
es in the Three Sisters
polyculture In agriculture, polyculture is the practice of growing more than one crop species in the same space, at the same time. In doing this, polyculture attempts to mimic the diversity of natural ecosystems. Polyculture is the opposite of monoculture, i ...
. The leafy stalk of the plant gives rise to male
inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...
s or tassels which produce
pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...
, and female inflorescences called
ears An ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists o ...
. The ears yield grain, known as
kernels Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine learnin ...
or seeds. In modern commercial varieties, these are usually yellow or white; other varieties can be of many colors. Maize relies on humans for its propagation. Since the
Columbian exchange The Columbian exchange, also known as the Columbian interchange, was the widespread transfer of plants, animals, precious metals, commodities, culture, human populations, technology, diseases, and ideas between the New World (the Americas) in ...
, it has become a
staple food A staple food, food staple, or simply a staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard diet for a given person or group of people, supplying a large fraction of energy needs and ...
in many parts of the world, with the total production of maize surpassing that of
wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
and
rice Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima ''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...
. Much maize is used for
animal feed Animal feed is food given to domestic animals, especially livestock, in the course of animal husbandry. There are two basic types: fodder and forage. Used alone, the word ''feed'' more often refers to fodder. Animal feed is an important input to ...
, whether as grain or as the whole plant, which can either be baled or made into the more palatable
silage Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage p ...
. Sugar-rich varieties called
sweet corn Sweet corn (''Zea mays'' convar. ''saccharata'' var. ''rugosa''), also called sugar corn and pole corn, is a variety of maize grown for human consumption with a high sugar content. Sweet corn is the result of a naturally occurring recessive muta ...
are grown for human consumption, while
field corn Field corn, also known as cow corn, is a North American term for maize (''Zea mays'') grown for livestock fodder (silage), ethanol, cereal, and processed food products. The principal field corn varieties are dent corn, flint corn, flour corn (also ...
varieties are used for animal feed, for uses such as
cornmeal Cornmeal is a meal (coarse flour) or a cell membrane ground from dried corn. It is a common staple food, and is ground to coarse, medium, and fine consistencies, but not as fine as wheat flour can be.Herbst, Sharon, ''Food Lover's Companion'', ...
or
masa ''Masa'' (or ''masa de maíz'') (; ) is a maize dough that comes from ground nixtamalization, nixtamalized corn. It is used for making corn tortillas, ''gorditas'', ''tamales'', ''pupusas'', and many other Latin American cuisine, Latin American d ...
,
corn starch Corn starch, maize starch, or cornflour (British English) is the starch derived from corn (maize) grain. The starch is obtained from the endosperm of the kernel. Corn starch is a common food ingredient, often used to thicken sauces or sou ...
,
corn syrup Corn syrup is a food syrup which is made from the starch of corn (called maize in many countries) and contains varying amounts of sugars: glucose, maltose and higher oligosaccharides, depending on the grade. Corn syrup is used in foods to softe ...
, pressing into
corn oil Corn oil (North American) or maize oil (British) is oil extracted from the germ of corn (maize). Its main use is in cooking, where its high smoke point makes refined corn oil a valuable frying oil. It is also a key ingredient in some margarines. ...
, alcoholic beverages like
bourbon whiskey Bourbon () is a type of barrel-aged American whiskey made primarily from corn. The name derives from the French Bourbon dynasty, although the precise source of inspiration is uncertain; contenders include Bourbon County in Kentucky and Bourbo ...
, and as chemical feedstocks including
ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
and other
biofuel Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil. According to the United States Energy Information Administration (E ...
s. Maize is cultivated throughout the world; a greater weight of maize is produced each year than any other grain. In 2020, world production was 1.1 billion tonnes. It is afflicted by many
pests PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...
and
diseases A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that ar ...
; two major
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
pests,
European corn borer The European corn borer (''Ostrinia nubilalis''), also known as the European corn worm or European high-flyer, is a moth of the family Crambidae which includes other grass moths. It is a pest of grain, particularly maize (''Zea mays''). The in ...
and
corn rootworms Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...
, have each caused annual losses of a billion dollars in the US. Modern
plant breeding Plant breeding is the science of changing the traits of plants in order to produce desired characteristics. It has been used to improve the quality of nutrition in products for humans and animals. The goals of plant breeding are to produce cro ...
has greatly increased output and qualities such as nutrition, drought, and tolerance of pests and diseases. Much maize is now
genetically modified Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of Genetic engineering techniques, technologies used to change the gene ...
. As a food, maize is used to make a wide variety of dishes including Mexican
tortilla A tortilla (, ) is a thin, circular unleavened flatbread originally made from maize hominy meal, and now also from wheat flour. The Aztecs and other Nahuatl speakers called tortillas ''tlaxcalli'' (). First made by the indigenous peoples of Me ...
s and
tamale A tamale, in Spanish tamal, is a traditional Mesoamerican dish made of masa, a dough made from nixtamalized corn, which is steamed in a corn husk or banana leaf. The wrapping can either be discarded prior to eating or used as a plate. Tamale ...
s, Italian
polenta Polenta (, ) is a dish of boiled cornmeal that was historically made from other grains. The dish comes from Italy. It may be served as a hot porridge, or it may be allowed to cool and solidify into a loaf that can be baked, fried, or grilled. ...
, and American
hominy Hominy (Spanish: maíz molido; literally meaning "milled corn") is a food produced from dried maize (corn) kernels that have been treated with an alkali, in a process called nixtamalization ( is the Nahuatl word for "hominy"). "Lye hominy" is a ...
grits Grits are a type of porridge made from boiled cornmeal. Hominy grits are a type of grits made from hominy – corn that has been treated with an alkali in a process called nixtamalization, with the pericarp (ovary wall) removed. Grits are oft ...
. Maize
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
is low in some
essential amino acid An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life form ...
s, and the
niacin Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
it contains only becomes available if freed by alkali treatment. In Mesoamerica, maize is personified as a maize god and depicted in sculptures.


History


Pre-Columbian development

Maize requires human intervention for it to propagate. The kernels of its naturally-propagating
teosinte ''Zea'' is a genus of flowering plants in the grass family. The best-known species is ''Z. mays'' (variously called maize, corn, or Indian corn), one of the most important crops for human societies throughout much of the world. The four wild sp ...
ancestor fall off the cob on their own, while those of
domesticated Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. A ...
maize do not. All maize arose from a single domestication in southern Mexico about 9,000 years ago. The oldest surviving maize types are those of the Mexican highlands. Maize spread from this region to the lowlands and over the Americas along two major paths. The centre of domestication was most likely the
Balsas River The Balsas River (Spanish Río Balsas, also locally known as the Mezcala River, or Atoyac River) is a major river of south-central Mexico. The basin flows through the states of Guerrero, México, Morelos, and Puebla. Downstream of Ciudad Al ...
valley of south-central Mexico. Maize reached highland Ecuador at least 8000 years ago. It reached lower Central America by 7600 years ago, and the valleys of the Colombian
Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
between 7000 and 6000 years ago. The earliest maize plants grew a single, small ear per plant. The
Olmec The Olmecs () were the earliest known major Mesoamerican civilization. Following a progressive development in Soconusco, they occupied the tropical lowlands of the modern-day Mexican states of Veracruz and Tabasco. It has been speculated that t ...
and
Maya Maya may refer to: Civilizations * Maya peoples, of southern Mexico and northern Central America ** Maya civilization, the historical civilization of the Maya peoples ** Maya language, the languages of the Maya peoples * Maya (Ethiopia), a populat ...
cultivated maize in numerous varieties throughout
Mesoamerica Mesoamerica is a historical region and cultural area in southern North America and most of Central America. It extends from approximately central Mexico through Belize, Guatemala, El Salvador, Honduras, Nicaragua, and northern Costa Rica. W ...
; they cooked, ground and processed it through
nixtamalization Nixtamalization () is a process for the preparation of corn, or other grain, in which the grain is soaked and cooked in an alkaline solution, usually limewater (but sometimes aqueous alkali metal carbonates), washed, and then hulled. The ter ...
. By 3000 years ago, maize was central to Olmec culture, including their calendar, language, and myths. The
Mapuche The Mapuche ( (Mapuche & Spanish: )) are a group of indigenous inhabitants of south-central Chile and southwestern Argentina, including parts of Patagonia. The collective term refers to a wide-ranging ethnicity composed of various groups who sha ...
people of south-central Chile cultivated maize along with
quinoa Quinoa (''Chenopodium quinoa''; , from Quechua ' or ') is a flowering plant in the amaranth family. It is a herbaceous annual plant grown as a crop primarily for its edible seeds; the seeds are rich in protein, dietary fiber, B vitamins, and ...
and
potatoes The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae. Wild potato species can be found from the southern United ...
in
pre-Hispanic In the history of the Americas, the pre-Columbian era spans from the original settlement of North and South America in the Upper Paleolithic period through European colonization, which began with Christopher Columbus's voyage of 1492. Usually, th ...
times. Before the expansion of the
Inca Empire The Inca Empire (also known as the Incan Empire and the Inka Empire), called ''Tawantinsuyu'' by its subjects, (Quechua for the "Realm of the Four Parts",  "four parts together" ) was the largest empire in pre-Columbian America. The admin ...
, maize was traded and transported as far south as 40° S in Melinquina,
Lácar Department Lácar is a department located in the south of Neuquén Province, Argentina. Geography The Department limits with Huiliches Department at North, Collón Cura Department at northeast, Rio Negro Province at southeast, Los Lagos Department at so ...
, Argentina, probably brought across the Andes from Chile.


Columbian exchange

After the arrival of Europeans in 1492, Spanish settlers consumed maize, and explorers and traders carried it back to Europe. Spanish settlers much preferred
wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
bread to maize. Maize flour could not be substituted for wheat for communion bread, since in
Christian Christians () are people who follow or adhere to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus Christ. The words ''Christ'' and ''Christian'' derive from the Koine Greek title ''Christós'' (Χρι ...
belief at that time only wheat could undergo
transubstantiation Transubstantiation (Latin: ''transubstantiatio''; Greek: μετουσίωσις ''metousiosis'') is, according to the teaching of the Catholic Church, "the change of the whole substance of bread into the substance of the Body of Christ and of th ...
and be transformed into the body of Christ. 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. By the 17th century, it was a common peasant food in Southern Europe. By the 18th century, it was the chief food of the southern French and Italian peasantry, especially as
polenta Polenta (, ) is a dish of boiled cornmeal that was historically made from other grains. The dish comes from Italy. It may be served as a hot porridge, or it may be allowed to cool and solidify into a loaf that can be baked, fried, or grilled. ...
in Italy. When maize was introduced into Western farming systems, it was welcomed for its productivity. However, a widespread problem of malnutrition soon arose wherever it had become a
staple food A staple food, food staple, or simply a staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard diet for a given person or group of people, supplying a large fraction of energy needs and ...
. Indigenous Americans had learned to soak maize in
alkali In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...
-water — made with ashes and
lime Lime commonly refers to: * Lime (fruit), a green citrus fruit * Lime (material), inorganic materials containing calcium, usually calcium oxide or calcium hydroxide * Lime (color), a color between yellow and green Lime may also refer to: Botany ...
— since at least 1200–1500 BC, creating the process of nixtamalization. They did this to liberate the corn hulls, but coincidentally it also liberated the B-vitamin
niacin Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
, the lack of which caused
pellagra Pellagra is a disease caused by a lack of the vitamin niacin (vitamin B3). Symptoms include inflamed skin, diarrhea, dementia, and sores in the mouth. Areas of the skin exposed to either sunlight or friction are typically affected first. Over t ...
. Once alkali processing and dietary variety were understood and applied, pellagra disappeared in the developed world. The development of high-
lysine Lysine (symbol Lys or K) is an α-amino acid that is a precursor to many proteins. It contains an α-amino group (which is in the protonated form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −C ...
maize and the promotion of a more balanced diet have contributed to its demise. Pellagra still exists in food-poor areas and refugee camps where people survive on donated maize.


Names

The name ''maize'' derives from the Spanish form of the
Taíno The Taíno were a historic Indigenous peoples of the Caribbean, indigenous people of the Caribbean whose culture has been continued today by Taíno descendant communities and Taíno revivalist communities. At the time of European contact in the ...
. The Swedish botanist
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, the ...
used the common name maize as the species epithet in ''Zea mays''. The name ''Maize'' is preferred in formal, scientific, and international usage as a
common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...
because it refers specifically to this one grain, unlike ''corn'', which has a complex variety of meanings that vary by context and geographic region. Most countries primarily use the term ''maize'', and the name ''corn'' is used mainly in the United States and a handful of other English-speaking countries. In countries that primarily use the term ''maize'', the word "corn" may denote any
cereal A cereal is any Poaceae, grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, Cereal germ, germ, and bran. Cereal Grain, grain crops are grown in greater quantit ...
crop, varying geographically with the local staple, such as wheat in England and oats in Scotland or Ireland. The usage of ''corn'' for maize started as a shortening of "Indian corn" in 18th century North America. The historian of food Betty Fussell writes in an article on the history of the word "corn" in North America that " say the word "corn" is to plunge into the tragi-farcical mistranslations of language and history". Similar to the British usage, the Spanish referred to maize as , a generic term for cereal grains, as did Italians with the term . The British later referred to maize as Turkey wheat, Turkey corn, or Indian corn; Fussell comments that "they meant not a place but a condition, a savage rather than a civilized grain". International groups such as the
Centre for Agriculture and Bioscience International CABI (legally CAB International, formerly Commonwealth Agricultural Bureaux) is a nonprofit intergovernmental development and information organisation focusing primarily on agricultural and environmental issues in the developing world, and th ...
consider maize the preferred common name. The word ''maize'' is used by the UN's
FAO The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
, and in the names of the
International Maize and Wheat Improvement Center The International Maize and Wheat Improvement Center (known - even in English - by its Spanish acronym CIMMYT for ''Centro Internacional de Mejoramiento de Maíz y Trigo'') is a non-profit research-for-development organization that develops im ...
of Mexico, the Indian Institute of Maize Research, the Maize Association of Australia, the National Maize Association of Nigeria, the National Maize Association of Ghana, the Maize Trust of South Africa, and the Zimbabwe Seed Maize Association.


Structure and physiology

Maize is a tall
annual Annual may refer to: * Annual publication, periodical publications appearing regularly once per year **Yearbook ** Literary annual * Annual plant * Annual report * Annual giving * Annual, Morocco, a settlement in northeastern Morocco * Annuals (b ...
grass with a single stem, ranging in height from to . The long narrow leaves arise from the
node In general, a node is a localized swelling (a "knot") or a point of intersection (a vertex). Node may refer to: In mathematics *Vertex (graph theory), a vertex in a mathematical graph *Vertex (geometry), a point where two or more curves, lines, ...
s or joints, alternately on opposite sides on the stalk. Maize is
monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is conne ...
, with separate male and female flowers on the same plant. At the top of the stem is the tassel, an
inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...
of male flowers; their anthers release pollen, which is dispersed by wind. Like other pollen, it is an
allergen An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies. In technical terms ...
, but most of it falls within a few meters of the tassel and the risk is largely restricted to farm workers. The female inflorescence, some way down the stem from the tassel, is first seen as a silk, a bundle of soft tubular hairs, one for the
carpel Gynoecium (; ) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ''pistils'' ...
in each female flower, which develops into a kernel (often called a seed. Botanically, as in all grasses, it is a fruit, fused with the seed coat to form a
caryopsis In botany, a caryopsis (plural caryopses) is a type of simple fruit—one that is monocarpellate (formed from a single carpel) and indehiscent (not opening at maturity) and resembles an achene, except that in a caryopsis the pericarp is fused ...
) when it is pollinated. A whole female inflorescence develops into an ear or
corncob A corncob, also called corn cob, cob of corn or corn on the cob, is the central core of an ear of corn (also known as maize). It is the part of the ear on which the kernels grow. The ear is also considered a "cob" or "pole" but it is not fully ...
, enveloped by multiple leafy layers or husks. The is the leaf most closely associated with a particular developing ear. This leaf and those above it contribute over three quarters of the carbohydrate (
starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...
) that fills the grain. The grains are usually yellow or white in modern varieties; other varieties have orange, red, brown,
blue Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when obs ...
,
purple Purple is any of a variety of colors with hue between red and blue. In the RGB color model used in computer and television screens, purples are produced by mixing red and blue light. In the RYB color model historically used by painters, pu ...
, or black grains. They are arranged in 8 to 32 rows around the cob; there can be up to 1200 grains on a large cob. Yellow maizes derive their color from
carotenoid Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic compound, organic pigments that are produced by plants and algae, as well as several bacteria, and Fungus, fungi. Carotenoids give the characteristic color to pumpki ...
s; red maizes are colored by
anthocyanin Anthocyanins (), also called anthocyans, are water-soluble vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart gave the name Anthokyan to a chemical compo ...
s and
phlobaphene Phlobaphenes (or phlobaphens, CAS No.:71663-19-9) are reddish, alcohol-soluble and water-insoluble phenolic substances. They can be extracted from plants, or be the result from treatment of tannin extracts with mineral acids (tanner's red). The nam ...
s; and orange and green varieties may contain combinations of these pigments. Maize has short-day
photoperiodism Photoperiodism is the physiological reaction of organisms to the length of night or a dark period. It occurs in plants and animals. Plant photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light a ...
, meaning that it requires nights of a certain length to flower. Flowering further requires enough warm days above . The control of flowering is set genetically; the physiological mechanism involves the
phytochrome Phytochromes are a class of photoreceptor in plants, bacteria and fungi used to detect light. They are sensitive to light in the red and far-red region of the visible spectrum and can be classed as either Type I, which are activated by far-re ...
system. Tropical cultivars can be problematic if grown in higher latitudes, as the longer days can make the plants grow tall instead of setting seed before winter comes. On the other hand, growing tall rapidly could be convenient for producing biofuel. Immature maize shoots accumulate a powerful antibiotic substance, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (
DIMBOA DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) is a naturally occurring hydroxamic acid, a benzoxazinoid. DIMBOA is a powerful antibiotic present in maize, wheat, rye, and related grasses, DIMBOA was first identified in maize in 1962 as ...
), which provides a measure of protection against a wide range of pests. Because of its shallow roots, maize is susceptible to droughts, intolerant of nutrient-deficient soils, and prone to being uprooted by severe winds. File:Corntassel 7095.jpg , Many small male flowers make up the male inflorescence, called the tassel. File:Cornsilk 7091.jpg , Female inflorescence, with young
silk Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the coc ...
File:GreenCorn.JPG , Stalks, ears and silk File:ZeaMays.jpg , Full-grown maize plants File:Klip kukuruza uzgojen u Međimurju (Croatia).JPG , Mature maize ear on a stalk
File:Männliche Blüte einer Maispflanze 2009-08-19.JPG , Male flowers File:Corn blooming.jpg , Mature silk


Genomics and genetics

Maize is
diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
with 20
chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
s. 83% of
allelic An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...
variation within the genome derives from its teosinte ancestors, primarily due to the freedom of ''Zea'' species to
outcross Out-crossing or out-breeding is the technique of crossing between different breeds. This is the practice of introducing distantly related genetic material into a breeding line, thereby increasing genetic diversity. Outcrossing can be a useful ...
.
Barbara McClintock Barbara McClintock (June 16, 1902 – September 2, 1992) was an American scientist and cytogeneticist who was awarded the 1983 Nobel Prize in Physiology or Medicine. McClintock received her PhD in botany from Cornell University in 1927. There s ...
used maize to validate her
transposon A transposable element (TE, transposon, or jumping gene) is a nucleic acid sequence in DNA that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Transpo ...
theory of "jumping genes", for which she won the 1983
Nobel Prize in Physiology or Medicine The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, accord ...
. Maize remains an important
model organism A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...
for genetics and
developmental biology Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of Regeneration (biology), regeneration, asexual reproduction, metamorphosis, and the growth and di ...
. The
MADS-box The MADS box is a conserved sequence motif. The genes which contain this motif are called the MADS-box gene family. The MADS box encodes the DNA-binding MADS domain. The MADS domain binds to DNA sequences of high similarity to the motif CC /Tsub>6G ...
motif is involved in the development of maize flowers. The Maize Genetics and Genomics Database is funded by the
US Department of Agriculture The United States Department of Agriculture (USDA) is the United States federal executive departments, federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, ...
to support maize research. The
International Maize and Wheat Improvement Center The International Maize and Wheat Improvement Center (known - even in English - by its Spanish acronym CIMMYT for ''Centro Internacional de Mejoramiento de Maíz y Trigo'') is a non-profit research-for-development organization that develops im ...
maintains a large collection of maize accessions tested and cataloged for insect resistance. In 2005, the US
National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National I ...
, Department of Agriculture, and the
Department of Energy A Ministry of Energy or Department of Energy is a government department in some countries that typically oversees the production of fuel and electricity; in the United States, however, it manages nuclear weapons development and conducts energy-rel ...
formed a consortium to sequence the maize
genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...
. The resulting DNA sequence data was deposited immediately into
GenBank The GenBank sequence database is an open access, annotated collection of all publicly available nucleotide sequences and their protein translations. It is produced and maintained by the National Center for Biotechnology Information (NCBI; a part ...
, a public repository for genome-sequence data. Sequencing of the maize genome was completed in 2008. In 2009, the consortium published results of its sequencing effort. The genome, 85% of which is composed of
transposon A transposable element (TE, transposon, or jumping gene) is a nucleic acid sequence in DNA that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Transpo ...
s, contains 32,540 genes. Much of it has been duplicated and reshuffled by helitrons, a group of
transposable element A transposable element (TE, transposon, or jumping gene) is a nucleic acid sequence in DNA that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Transp ...
s within maize's DNA.


Breeding


Conventional breeding

Maize breeding in prehistory resulted in large plants producing large ears. Modern
breeding Breeding is sexual reproduction that produces offspring, usually animals or plants. It can only occur between a male and a female animal or plant. Breeding may refer to: * Animal husbandry, through selected specimens such as dogs, horses, and rab ...
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 mass selection (a row of plants is grown from seeds of one parent), the choosing of plants after pollination (which means that only the female parents are known). Later breeding efforts included ear to row selection (C. G. Hopkins c. 1896), hybrids made from selected
inbred Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and o ...
lines (G. H. Shull, 1909), and the highly successful double cross hybrids using four inbred lines ( D. F. Jones c. 1918, 1922). University-supported breeding programs were especially important in developing and introducing modern hybrids. 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. 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. Certain varieties of maize have been bred to produce many ears; these are the source of the "
baby corn An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...
" used as a vegetable in
Asian cuisine Asian cuisine includes several major regional cuisines: Central Asian, East Asian, North Asian, South Asian, Southeast Asian, and West Asian. A cuisine is a characteristic style of cooking practices and traditions, usually associated with ...
. A fast-flowering variety named mini-maize was developed to aid scientific research, as multiple generations can be obtained in a single year. One strain called olotón has evolved a symbiotic relationship with
nitrogen-fixing Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmos ...
microbes, which provides the plant with 29%–82% of its nitrogen. The
International Maize and Wheat Improvement Center The International Maize and Wheat Improvement Center (known - even in English - by its Spanish acronym CIMMYT for ''Centro Internacional de Mejoramiento de Maíz y Trigo'') is a non-profit research-for-development organization that develops im ...
(CIMMYT) operates a conventional breeding program to provide optimized strains. The program began in the 1980s. Hybrid seeds are distributed in Africa by its Drought Tolerant Maize for Africa project. Tropical
landrace A landrace is a domesticated, locally adapted, often traditional variety of a species of animal or plant that has developed over time, through adaptation to its natural and cultural environment of agriculture and pastoralism, and due to isolation ...
s remain an important and underused source of resistance alleles – both those for disease and for herbivores. Such alleles can then be
introgressed Introgression, also known as introgressive hybridization, in genetics is the transfer of genetic material from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. Intr ...
into productive varieties. Rare alleles for this purpose were discovered by Dao and Sood, both in 2014. In 2018, Zerka Rashid of CIMMYT used its
association mapping In genetics, association mapping, also known as "linkage disequilibrium mapping", is a method of mapping quantitative trait loci (QTLs) that takes advantage of historic linkage disequilibrium to link phenotypes (observable characteristics) to genoty ...
panel, developed for tropical drought tolerance traits. to find new
genomic Genomics is an interdisciplinary field of biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, three-dim ...
regions providing
sorghum downy mildew resistance ''Peronosclerospora sorghi'' is a plant pathogen. It is the causal agent of sorghum downy mildew. The pathogen is a fungal-like protist in the oomycota, or water mold, class. ''Peronosclerospora sorghi'' infects susceptible plants though sexual o ...
, and to further characterize known
differentially methylated region Differentially methylated regions (DMRs) are genomic regions with different DNA methylation status across different biological samples and regarded as possible functional regions involved in gene transcriptional regulation. The biological samples ...
s.


Genetic engineering

Genetically modified maize Genetically modified maize (corn) is a genetically modified crop. Specific maize strains have been genetically engineered to express agriculturally-desirable traits, including resistance to pests and to herbicides. Maize strains with both trai ...
was one of the 26
genetically engineered food Genetically modified foods (GM foods), also known as genetically engineered foods (GE foods), or bioengineered foods are foods produced from organisms that have had changes introduced into their DNA using the methods of genetic engineering. Gene ...
crops grown commercially in 2016. The vast majority of this is
Bt maize Genetically modified maize (maize, corn) is a genetically modified crop. Specific maize strains have been genetic engineering, genetically engineered to express agriculturally-desirable Phenotypic trait, traits, including resistance to pests and ...
. Genetically modified maize has been grown since 1997 in the United States and Canada; by 2016, 92% of the US maize crop was genetically modified. As of 2011, herbicide-tolerant maize and insect-resistant maize varieties were each grown in over 20 countries. In September 2000, up to $50 million worth of food products were recalled due to the presence of
Starlink Starlink is a satellite internet constellation operated by SpaceX, providing satellite Internet access coverage to 45 countries. It also aims for global mobile phone service after 2023. SpaceX started launching Starlink satellites in 2019. As ...
genetically modified corn, which had been approved only for animal consumption.


Origin


External phylogeny

The maize
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''Zea'' is relatively closely related to
sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many othe ...
, both being in the
PACMAD clade The PACMAD clade (previously PACCMAD, PACCAD, or PACC) is one of two major lineages (or clades) of the true grasses (Poaceae), regrouping six subfamilies and about 5700 species, more than half of all true grasses. Its sister group is the BOP c ...
of Old World grasses, and much more distantly to
rice Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima ''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...
and
wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
, which are in the other major group of grasses, the
BOP clade The BOP clade (sometimes ''BEP clade'') is one of two major lineages (or clades) of undefined taxonomic rank in the grasses (Poaceae), containing more than 5,400 species, about half of all grasses. Its sister group is the PACMAD clade; contrary ...
. It is closely related to ''
Tripsacum ''Tripsacum'' is a genus of plants in the grass family native to the Western Hemisphere. Gamagrass is a common name for plants in this genus. Species formerly included see ''Anthephora Apluda Chionachne Coelorachis Elionurus Hackelochloa Hem ...
'', gamagrass.


Maize and teosinte

Maize is the domesticated variant of the four species of
teosinte ''Zea'' is a genus of flowering plants in the grass family. The best-known species is ''Z. mays'' (variously called maize, corn, or Indian corn), one of the most important crops for human societies throughout much of the world. The four wild sp ...
s, which are its
crop wild relative A crop wild relative (CWR) is a wild plant closely related to a domesticated plant. It may be a wild ancestor of the domesticated (cultivated) plant or another closely related taxon. Overview The wild relatives of crop plants constitute an i ...
s. The teosinte origin theory was proposed by the Russian botanist
Nikolai Ivanovich Vavilov Nikolai Ivanovich Vavilov ( rus, Никола́й Ива́нович Вави́лов, p=nʲɪkɐˈlaj ɪˈvanəvʲɪtɕ vɐˈvʲiləf, a=Ru-Nikolay_Ivanovich_Vavilov.ogg; – 26 January 1943) was a Russian and Soviet agronomist, botanist a ...
in 1931, and the American
Nobel Prize The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...
-winner
George Beadle George Wells Beadle (October 22, 1903 – June 9, 1989) was an American geneticist. In 1958 he shared one-half of the Nobel Prize in Physiology or Medicine with Edward Tatum for their discovery of the role of genes in regulating biochemical even ...
in 1932. 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'', ) and teosinte branched-1 (''tb1'', ). In the late 1930s,
Paul Mangelsdorf Paul Christoph Mangelsdorf (born in Atchison, Kansas on July 20, 1899; died July 22, 1989) was an American botanist and agronomist, known for his work on the origins of maize. Early life and education His father was a Prussian immigrant and his mot ...
suggested that domesticated maize was the result of a hybridization event between an unknown wild maize and a species of ''
Tripsacum ''Tripsacum'' is a genus of plants in the grass family native to the Western Hemisphere. Gamagrass is a common name for plants in this genus. Species formerly included see ''Anthephora Apluda Chionachne Coelorachis Elionurus Hackelochloa Hem ...
'', a related genus; this has been refuted by modern
genetic testing Genetic testing, also known as DNA testing, is used to identify changes in DNA sequence or chromosome structure. Genetic testing can also include measuring the results of genetic changes, such as RNA analysis as an output of gene expression, or ...
. In 2004,
John Doebley John F. Doebley is an American botanical geneticist whose main area of interest is how genes drive plant development and evolution. He has spent the last two decades examining the genetic differences and similarities between teosinte and maize and ...
identified Balsas teosinte, ''Zea mays'' ssp. ''parviglumis'', native to the
Balsas River The Balsas River (Spanish Río Balsas, also locally known as the Mezcala River, or Atoyac River) is a major river of south-central Mexico. The basin flows through the states of Guerrero, México, Morelos, and Puebla. Downstream of Ciudad Al ...
valley in Mexico's southwestern highlands, as the
crop wild relative A crop wild relative (CWR) is a wild plant closely related to a domesticated plant. It may be a wild ancestor of the domesticated (cultivated) plant or another closely related taxon. Overview The wild relatives of crop plants constitute an i ...
genetically most similar to modern maize. The middle part of the short Balsas River valley is the likely location of early domestication. 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 Iguala (), known officially as Iguala de la Independencia, is a historic city located from the state capital of Chilpancingo, in the Mexican state of Guerrero in southwestern Mexico. Geography The city of Iguala stands on Federal Highway 95 abo ...
.
Doebley and colleagues showed in 2002 that maize had been domesticated only once, about 9,000 years ago, and then spread throughout the Americas. Maize pollen dated to 7,300 years ago from San Andres, Tabasco has been found on the Caribbean coast. 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 The Central Valleys ( es, Valles Centrales) of Oaxaca, also simply known as the Oaxaca Valley, is a geographic region located within the modern-day state of Oaxaca in southern Mexico. In an administrative context, it has been defined as comprising ...
, are roughly 6,250 years old; the oldest ears from caves near Tehuacan, Puebla, are 5,450 years old.


Spreading to the north

Around 4,500 years ago, maize began to spread to the north. In the United States, maize was first cultivated at several sites in New Mexico and Arizona about 4,100 years ago. 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. 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 Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and Freshwater bivalve, freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other ...
s, which are very sensitive to environmental changes.


Agronomy


Growing

Because it is cold-intolerant, in the
temperate zones In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
maize must be planted in the spring. Its
root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...
system is generally shallow, so the plant is dependent on soil moisture. As a plant that uses carbon fixation, maize is a considerably more water-efficient crop than plants that use carbon fixation such as
alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as w ...
and
soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean, which has numerous uses. Traditional unfermented food uses of soybeans include soy milk, from which tofu an ...
s. 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
Fourth of July Independence Day (colloquially the Fourth of July) is a federal holiday in the United States commemorating the Declaration of Independence, which was ratified by the Second Continental Congress on July 4, 1776, establishing the United States ...
", although modern hybrids generally exceed this growth rate. Maize used for
silage Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage p ...
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 A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D.  Jiang, A.  Khan, W.  Pokam Mba, D.  Rosenfeld, J. Tierney, an ...
regularly causes maize crop failure and consequent
famine A famine is a widespread scarcity of food, caused by several factors including war, natural disasters, crop failure, Demographic trap, population imbalance, widespread poverty, an Financial crisis, economic catastrophe or government policies. Th ...
. Although it is grown mainly in wet, hot climates, it can thrive in cold, hot, dry or wet conditions, meaning that it is an extremely versatile crop. Maize was planted by the Native Americans in small hills of soil, in the
polyculture In agriculture, polyculture is the practice of growing more than one crop species in the same space, at the same time. In doing this, polyculture attempts to mimic the diversity of natural ecosystems. Polyculture is the opposite of monoculture, i ...
system called the Three Sisters. Maize provided support for
bean A bean is the seed of several plants in the family Fabaceae, which are used as vegetables for human or animal food. They can be cooked in many different ways, including boiling, frying, and baking, and are used in many traditional dishes th ...
s; the beans provided nitrogen derived from nitrogen-fixing
rhizobia Rhizobia are diazotrophic bacteria that fix nitrogen after becoming established inside the root nodules of legumes (Fabaceae). To express genes for nitrogen fixation, rhizobia require a plant host; they cannot independently fix nitrogen. In gene ...
bacteria which live on the roots of beans and other
legume A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock f ...
s; and
squashes Squash may refer to: Sports * Squash (sport), the high-speed racquet sport also known as squash racquets * Squash (professional wrestling), an extremely one-sided match in professional wrestling * Squash tennis, a game similar to squash but pla ...
provided ground cover to stop weeds and inhibit evaporation by providing shade over the soil. File:Plàntules moresc 2012.JPG, Seedlings three weeks after sowing File:Corn Zea mays Plant Row 2000px.jpg, Young stalks File:Maispflanze.jpg, Mature plants showing ears


Harvesting

Sweet corn, harvested earlier than maize grown for grain, grows to maturity in a period of from 60 to 100 days according to variety. An extended sweet corn harvest, picked at the milk stage, can be arranged either by planting a selection of varieties which ripen earlier and later, or by planting different areas at fortnightly intervals. 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 can be harvested and stored in the husk leaves if kept dry. Before
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, most maize in North America was harvested by hand. This involved a large number of workers and associated social events (husking or shucking
bees Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfamil ...
). 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
stover Stover are the leaves and stalks of field crops, such as corn (maize), sorghum or soybean that are commonly left in a field after harvesting the grain. It is similar to straw, the residue left after any cereal grain or grass has been harvested a ...
) and corn binders, which are
reaper-binder The reaper-binder, or binder, is a farm implement that improved upon the simple reaper. The binder was invented in 1872 by Charles Baxter Withington, a jeweler from Janesville, Wisconsin. In addition to cutting the small-grain crop, a binder also ...
s designed specifically for maize. The latter produce sheaves that can be shocked. By hand or mechanical picker, the entire ear is harvested, which 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 A corn crib or corncrib is a type of granary used to dry and store corn. It may also be known as a cornhouse or corn house. Overview After the harvest and while still on the cob, corn is placed in the crib either with or without the husk. The ...
s, sufficient for some livestock feeding uses. 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 The modern combine harvester, or simply combine, is a versatile machine designed to efficiently harvest a variety of grain crops. The name derives from its combining four separate harvesting operations—reaping, threshing, gathering, and winnow ...
and store it in 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 Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have c ...
for the
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
. 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. File:Iowa harvest 2009.jpg, Harvesting maize, Iowa File:Maissipelto Rantasalmi.jpg, Harvesting maize, Finland File:MyanmarCorn3.jpg, Hand-picking maize, Myanmar


Grain storage

Drying is vital to prevent or at least reduce damage by mould fungi, which contaminate the grain with
mycotoxin A mycotoxin (from the Greek μύκης , "fungus" and τοξίνη , "toxin") is a toxic secondary metabolite produced by organisms of kingdom Fungi and is capable of causing disease and death in both humans and other animals. The term 'mycotoxin' ...
s. ''
Aspergillus ' () is a genus consisting of several hundred mold species found in various climates worldwide. ''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...
'' and ''
Fusarium ''Fusarium'' is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the soil mi ...
'' spp. are the most common mycotoxin sources, and accordingly important in agriculture. If the moisture content of the harvested grain is too high, 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 Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used a ...
or
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
) and electricity to power the blowers.


Production

Maize is widely cultivated throughout the world, and a greater weight of maize is produced each year than any other grain. In 2020, total world production was 1.16 billion
tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1000  kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s, led by the United States with 31.0% of the total (table). China produced 22.4% of the global total. File:Production of maize (2019).svg, Production of maize (2019) File:World Production Of Primary Crops, Main Commodities.svg, Maize (pink strip) is the second most widely produced primary crop, after
sugarcane Sugarcane or sugar cane is a species of (often hybrid) tall, Perennial plant, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar Sugar industry, production. The plants are 2–6 m (6–20 ft) tall with ...
, and the first among grain crops.


Pests

Many pests can affect maize growth and development, including invertebrates, weeds, and pathogens. Maize is susceptible to a large number of fungal, bacterial, and viral
plant disease Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomyc ...
s. Those of economic importance include diseases of the leaf, smuts such as
corn smut Corn smut is a plant disease caused by the pathogenic fungus ''Ustilago maydis'' that causes smut on maize and teosinte. The fungus forms galls on all above-ground parts of corn species. It is edible, and is known in Mexico as the delicacy ' ...
, ear rots and stalk rots.
Northern corn leaf blight Northern corn leaf blight (NCLB) or Turcicum leaf blight (TLB) is a foliar disease of corn (maize) caused by ''Exserohilum turcicum'', the anamorph of the ascomycete '' Setosphaeria turcica''. With its characteristic cigar-shaped lesions, this di ...
damages maize throughout its range, whereas banded leaf and sheath blight is a problem in Asia. Some fungal diseases of maize produce potentially dangerous
mycotoxin A mycotoxin (from the Greek μύκης , "fungus" and τοξίνη , "toxin") is a toxic secondary metabolite produced by organisms of kingdom Fungi and is capable of causing disease and death in both humans and other animals. The term 'mycotoxin' ...
s such as
aflatoxin Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly ''Aspergillus'' species. The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, sweetcorn ...
. In the United States, major diseases include
tar spot ''Rhytisma acerinum'' is a plant pathogen that commonly affects sycamores and maples in late summer and autumn, causing tar spot. Tar spot does not usually have an adverse effect on the trees' long-term health. ''R. acerinum'' is an Ascomycete f ...
,
bacterial leaf streak Bacterial leaf streak (BLS), also known as black chaff, is a common bacterial disease of wheat. The disease is caused by the bacterial species '' Xanthomonas translucens'' pv. ''undulosa''. The pathogen is found globally, but is a primary problem ...
,
gray leaf spot Gray leaf spot (GLS) is a foliar fungal disease that affects grasses. In grasses other than maize it is caused by '' Pyricularia grisea'', which only infects perennial ryegrass, tall fescue, and St. Augustine grass in places with warm and rainy cl ...
, northern corn leaf blight, and
Goss's wilt ''Clavibacter michiganensis'' is an aerobic non-sporulating Gram-positive plant pathogenic actinomycete of the genus ''Clavibacter''. ''Clavibacter michiganensis'' has several subspecies. ''Clavibacter michiganensis'' subsp. ''michiganensis'' ...
; in 2022, the most damaging disease was tar spot, which caused losses of 116.8 million
bushels A bushel (abbreviation: bsh. or bu.) is an imperial and US customary unit of volume based upon an earlier measure of dry capacity. The old bushel is equal to 2 kennings (obsolete), 4 pecks, or 8 dry gallons, and was used mostly for agricultu ...
. Maize sustains a billion dollars' worth of losses annually in the US from each of two major insect
pests PESTS was an anonymous American activist group formed in 1986 to critique racism, tokenism, and exclusion in the art world. PESTS produced newsletters, posters, and other print material highlighting examples of discrimination in gallery represent ...
, namely the
European corn borer The European corn borer (''Ostrinia nubilalis''), also known as the European corn worm or European high-flyer, is a moth of the family Crambidae which includes other grass moths. It is a pest of grain, particularly maize (''Zea mays''). The in ...
or ECB (''Ostrinia nubilalis'') and corn rootworms (''
Diabrotica ''Diabrotica'' is a large, widespread genus of beetles in the family Chrysomelidae. Members of this genus include several destructive agricultural pest species, sometimes referred to as cucumber beetles or corn rootworms. Species * '' Diabrotic ...
spp'')
western corn rootworm The Western corn rootworm, ''Diabrotica virgifera virgifera'', is one of the most devastating corn rootworm species in North America, especially in the midwestern corn-growing areas such as Iowa. A related species, the Northern corn rootworm, ...
, northern corn rootworm, and southern corn rootworm. Another serious pest is the
fall armyworm The fall armyworm (''Spodoptera frugiperda'') is a species in the order Lepidoptera and one of the species of the fall armyworm moths distinguished by their larval life stage. The term "armyworm" can refer to several species, often describing th ...
(''Spodoptera frugiperda''). The
maize weevil Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...
(''Sitophilus zeamais'') is a serious pest of stored grain. The Northern armyworm, Oriental armyworm or Rice ear-cutting caterpillar (''
Mythimna separata ''Mythimna separata'', the northern armyworm, oriental armyworm or rice ear-cutting caterpillar, is a moth of the family Noctuidae. It is found in China, Japan, South-east Asia, India, eastern Australia, New Zealand, and some Pacific islands. It ...
'') is a major pest of maize in Asia.
Nematode The nematodes ( or grc-gre, Νηματώδη; la, Nematoda) or roundworms constitute the phylum Nematoda (also called Nemathelminthes), with plant-Parasitism, parasitic nematodes also known as eelworms. They are a diverse animal phylum inhab ...
s too are pests of maize. It is likely that every maize plant harbors some nematode
parasites Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of lif ...
, and populations of ''
Pratylenchus ''Pratylenchus'' is a genus of nematodes known commonly as lesion nematodes.Crow, W. TAmaryllis lesion nematode, ''Pratylenchus hippeastri''.EENY-546. University of Florida IFAS. 2012. They are parasitic on plants and are responsible for root le ...
'' lesion nematodes in the roots can be "enormous". The effects on the plants include stunting, sometimes of whole fields, sometimes in patches, especially when there is also water stress and poor control of weeds. Many plants, both
monocot Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...
s (grasses) such as ''
Echinochloa crus-galli ''Echinochloa crus-galli'' is a type of wild grass originating from tropical Asia that was formerly classified as a type of panicum grass. It is commonly known as cockspur (or cockspur grass), barnyard millet, Japanese millet, water grass, common ...
'' (barnyard grass) and
dicot The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, t ...
s (forbs) such as ''
Chenopodium ''Chenopodium'' is a genus of numerous species of perennial or annual herbaceous flowering plants known as the goosefoots, which occur almost anywhere in the world. It is placed in the family Amaranthaceae in the APG II system; older classifica ...
'' and ''
Amaranth ''Amaranthus'' is a cosmopolitan genus of annual or short-lived perennial plants collectively known as amaranths. Some amaranth species are cultivated as leaf vegetables, pseudocereals, and ornamental plants. Catkin-like cymes of densely pack ...
us'' may compete with maize and reduce crop yields. Control may involve mechanical weed removal, flame weeding, or herbicides. File:European Corn Borer (15350098570).jpg, Caterpillar of
European corn borer The European corn borer (''Ostrinia nubilalis''), also known as the European corn worm or European high-flyer, is a moth of the family Crambidae which includes other grass moths. It is a pest of grain, particularly maize (''Zea mays''). The in ...
in maize File:Symptoms corncobs destruction caused by Ostrinia nubilalis (cropped).JPG, Corncob damage by European corn borer


Uses


Culinary

Maize and
cornmeal Cornmeal is a meal (coarse flour) or a cell membrane ground from dried corn. It is a common staple food, and is ground to coarse, medium, and fine consistencies, but not as fine as wheat flour can be.Herbst, Sharon, ''Food Lover's Companion'', ...
(ground dried maize) constitute a
staple food A staple food, food staple, or simply a staple, is a food that is eaten often and in such quantities that it constitutes a dominant portion of a standard diet for a given person or group of people, supplying a large fraction of energy needs and ...
in many regions of the world. Maize is used to produce the food ingredient
cornstarch Corn starch, maize starch, or cornflour (British English) is the starch derived from corn (maize) grain. The starch is obtained from the endosperm of the kernel. Corn starch is a common food ingredient, often used to thicken sauces or soups, ...
. Maize starch can be
hydrolyzed Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...
and
enzymatically Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...
treated to produce
high fructose corn syrup High-fructose corn syrup (HFCS), also known as glucose–fructose, isoglucose and glucose–fructose syrup, is a sweetener made from corn starch. As in the production of conventional corn syrup, the starch is broken down into glucose by enzym ...
, a sweetener. Maize may be fermented and distilled to produce
Bourbon whiskey Bourbon () is a type of barrel-aged American whiskey made primarily from corn. The name derives from the French Bourbon dynasty, although the precise source of inspiration is uncertain; contenders include Bourbon County in Kentucky and Bourbo ...
.Kiniry, Laura.
Where Bourbon Really Got Its Name and More Tips on America's Native Spirit
. ''Smithsonian.com''. June 13, 2013.
Corn oil Corn oil (North American) or maize oil (British) is oil extracted from the germ of corn (maize). Its main use is in cooking, where its high smoke point makes refined corn oil a valuable frying oil. It is also a key ingredient in some margarines. ...
is extracted from the
germ Germ or germs may refer to: Science * Germ (microorganism), an informal word for a pathogen * Germ cell, cell that gives rise to the gametes of an organism that reproduces sexually * Germ layer, a primary layer of cells that forms during embry ...
of the grain.Corn Refiners Association
Corn Oil
5th Edition. 2006
In prehistoric times, Mesoamerican women used a ''
metate A metate (or mealing stone) is a type or variety of quern, a ground stone tool used for processing grain and seeds. In traditional Mesoamerican cultures, metates are typically used by women who would grind nixtamalized maize and other organic ma ...
'' quern to grind maize into cornmeal. 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 Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
, an important nutrient, it is not
bioavailable In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. Ho ...
without the process of
nixtamalization Nixtamalization () is a process for the preparation of corn, or other grain, in which the grain is soaked and cooked in an alkaline solution, usually limewater (but sometimes aqueous alkali metal carbonates), washed, and then hulled. The ter ...
. The Maya used nixtamal meal to make porridges and tamales. Maize is a staple of
Mexican cuisine Mexican cuisine consists of the cooking cuisines and traditions of the modern country of Mexico. Its earliest roots lie in Mesoamerican cuisine. Its ingredients and methods begin with the first agricultural communities such as the Olmec and M ...
.
Masa ''Masa'' (or ''masa de maíz'') (; ) is a maize dough that comes from ground nixtamalization, nixtamalized corn. It is used for making corn tortillas, ''gorditas'', ''tamales'', ''pupusas'', and many other Latin American cuisine, Latin American d ...
(''nixtamal'') is the main ingredient for
tortilla A tortilla (, ) is a thin, circular unleavened flatbread originally made from maize hominy meal, and now also from wheat flour. The Aztecs and other Nahuatl speakers called tortillas ''tlaxcalli'' (). First made by the indigenous peoples of Me ...
s,
atole ''Atole'' (, from Nahuatl '' ātōlli'' ), also known as ''atolli'' and ''atol de elote'', is a traditional hot corn- and masa-based beverage of Mexican origin. Chocolate ''atole'' is known as ''champurrado'' or ''atole''. It typically accomp ...
and many other dishes of Central American food. It is the main ingredient of
corn tortilla In North America, a corn tortilla or just tortilla (, ) is a type of thin, unleavened flatbread, made from hominy, that is the whole kernels of maize treated with alkali to improve their nutrition in a process called nixtamalization. A simple do ...
,
tamale A tamale, in Spanish tamal, is a traditional Mesoamerican dish made of masa, a dough made from nixtamalized corn, which is steamed in a corn husk or banana leaf. The wrapping can either be discarded prior to eating or used as a plate. Tamale ...
s,
atole ''Atole'' (, from Nahuatl '' ātōlli'' ), also known as ''atolli'' and ''atol de elote'', is a traditional hot corn- and masa-based beverage of Mexican origin. Chocolate ''atole'' is known as ''champurrado'' or ''atole''. It typically accomp ...
and the dishes based on these. The corn smut fungus, known as ''
huitlacoche Corn smut is a plant disease caused by the pathogenic fungus ''Ustilago maydis'' that causes smut on maize and teosinte. The fungus forms galls on all above-ground parts of corn species. It is edible, and is known in Mexico as the delicacy ''h ...
'', which grows on maize, is a Mexican delicacy. Coarse maize meal is made into a thick
porridge Porridge is a food made by heating or boiling ground, crushed or chopped starchy plants, typically grain, in milk or water. It is often cooked or served with added flavourings such as sugar, honey, (dried) fruit or syrup to make a sweet cereal, ...
in many cultures: from the
polenta Polenta (, ) is a dish of boiled cornmeal that was historically made from other grains. The dish comes from Italy. It may be served as a hot porridge, or it may be allowed to cool and solidify into a loaf that can be baked, fried, or grilled. ...
of Italy, the ''angu'' of Brazil, the ''
mămăligă Mămăligă (;) is a porridge made out of yellow maize flour, traditional in Romania, Moldova and West Ukraine. Poles from the Lviv area also prepare this traditional dish. It is also a traditional dish in Thessaly and Fthiotis, Greece. In Ital ...
'' of Romania, to
cornmeal mush Mush is a type of cornmeal pudding (or porridge) which is usually boiled in water or milk. It is often allowed to set, or gel into a semisolid, then cut into flat squares or rectangles, and pan fried. Usage is especially common in the Eastern U ...
in the US (or
hominy Hominy (Spanish: maíz molido; literally meaning "milled corn") is a food produced from dried maize (corn) kernels that have been treated with an alkali, in a process called nixtamalization ( is the Nahuatl word for "hominy"). "Lye hominy" is a ...
grits Grits are a type of porridge made from boiled cornmeal. Hominy grits are a type of grits made from hominy – corn that has been treated with an alkali in a process called nixtamalization, with the pericarp (ovary wall) removed. Grits are oft ...
in the Southern US) or the food called
mieliepap Ugali or Posho or sima (for others, see ) is a type of maize meal made from maize or corn flour in several countries in Africa. Sima is sometimes made from other flours, such as millet or sorghum flour, and is sometimes mixed with cassava flou ...
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.
Sweet corn Sweet corn (''Zea mays'' convar. ''saccharata'' var. ''rugosa''), also called sugar corn and pole corn, is a variety of maize grown for human consumption with a high sugar content. Sweet corn is the result of a naturally occurring recessive muta ...
, a genetic variety that is high in sugars and low in starch, is eaten in the unripe state as
corn on the cob Corn on the cob is a culinary term for a cooked :wikt:ear#earofcorn, ear of sweet corn (maize) eaten directly off the corncob, cob. The ear is picked while the endosperm is in the "milk stage" so that the caryopsis, kernels are still tender. E ...
. File:Corn, the food of the nation, US Food Administration poster, 1918.jpg, Poster of maize-based foods,
US Food Administration, 1918 File:Summer corn (48286638996).jpg, Semi-peeled corn on the cob File:ChiapasTamale2.JPG, Mexican
tamales A tamale, in Spanish tamal, is a traditional Mesoamerican dish made of masa, a dough made from nixtamalized corn, which is steamed in a corn husk or banana leaf. The wrapping can either be discarded prior to eating or used as a plate. Tamales ...
File:Polenta.jpg, One way of serving Italian
polenta Polenta (, ) is a dish of boiled cornmeal that was historically made from other grains. The dish comes from Italy. It may be served as a hot porridge, or it may be allowed to cool and solidify into a loaf that can be baked, fried, or grilled. ...


Nutritional value

Raw, yellow, sweet maize kernels are composed of 76% water, 19%
carbohydrates In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or may ...
, 3%
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
, and 1%
fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers spec ...
(table). In a 100-
gram The gram (originally gramme; SI unit symbol g) is a Physical unit, unit of mass in the International System of Units (SI) equal to one one thousandth of a kilogram. Originally defined as of 1795 as "the absolute weight of a volume of pure wate ...
serving, maize kernels provide 86
calories The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of on ...
and are a good source (10–19% of the
Daily Value The Reference Daily Intake (RDI) used in nutrition labeling on food and dietary supplement products in the U.S. and Canada is the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97–98% of health ...
) of the
B vitamins B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism and synthesis of red blood cells. Though these vitamins share similar names (B1, B2, B3, etc.), they are chemically distinct compounds that often coexist ...
,
thiamin Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, that cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thia ...
,
niacin Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
(if freed),
pantothenic acid Pantothenic acid, also called vitamin B5 is a water-soluble B vitamin and therefore an essential nutrient. All animals require pantothenic acid in order to synthesize coenzyme A (CoA) – essential for fatty acid metabolism – as well as to, i ...
(B5) and
folate Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...
. Maize has suboptimal amounts of the
essential amino acid An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life form ...
s
tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α- carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic ...
and
lysine Lysine (symbol Lys or K) is an α-amino acid that is a precursor to many proteins. It contains an α-amino group (which is in the protonated form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −C ...
, which accounts for its lower status as a protein source. The proteins of beans and legumes complement those of maize.


Animal feed

Maize is a major source of
animal feed Animal feed is food given to domestic animals, especially livestock, in the course of animal husbandry. There are two basic types: fodder and forage. Used alone, the word ''feed'' more often refers to fodder. Animal feed is an important input to ...
. As a grain crop, the dried
kernels Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine learnin ...
are used as feed. They are often kept on the cob for storage in a
corn crib A corn crib or corncrib is a type of granary used to dry and store corn. It may also be known as a cornhouse or corn house. Overview After the harvest and while still on the cob, corn is placed in the crib either with or without the husk. The ...
, or they may be shelled off for storage in a
grain bin A silo (from the Greek σιρός – ''siros'', "pit for holding grain") is a structure for storing bulk materials. Silos are used in agriculture to store fermented feed known as silage, not to be confused with a grain bin, which is used t ...
. When the grain is used for feed, the rest of the plant (the
corn stover Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
) can be used later as
fodder Fodder (), also called provender (), is any agriculture, agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, domestic rabbit, rabbits, sheep, horses, chickens and pigs. "Fodder" refers particularly to food g ...
,
bedding Bedding, also known as bedclothes or bed linen, is the materials laid above the mattress of a bed for hygiene, warmth, protection of the mattress, and decorative effect. Bedding is the removable and washable portion of a human sleeping environm ...
(litter), or
soil conditioner A soil conditioner is a product which is added to soil to improve the soil’s physical qualities, usually its fertility (ability to provide nutrition for plants) and sometimes its mechanics. In general usage, the term "soil conditioner" is often ...
. When the whole maize plant (grain plus stalks and leaves) is used for fodder, it is usually
chopped Chopped can have the following meanings: * Chopped and screwed Chopped and screwed (also called screwed and chopped or slowed and throwed) is a music genre and technique of remixing music that involves slowing down the tempo and deejaying. It ...
and made into
silage Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage p ...
, as this is more digestible and more palatable to ruminants than the dried form. Traditionally, maize was gathered into shocks after harvesting, where it dried further. It could then be stored for months until fed to livestock. Silage can be made in
silo A silo (from the Greek σιρός – ''siros'', "pit for holding grain") is a structure for storing bulk materials. Silos are used in agriculture to store fermented feed known as silage, not to be confused with a grain bin, which is used t ...
s or in silage wrappers. In the tropics, maize is harvested year-round and fed as green forage to the animals. Baled cornstalks offer an alternative to
hay Hay is grass, legumes, or other herbaceous plants that have been cut and dried to be stored for use as animal fodder, either for large grazing animals raised as livestock, such as cattle, horses, goats, and sheep, or for smaller domesticated ...
for
animal feed Animal feed is food given to domestic animals, especially livestock, in the course of animal husbandry. There are two basic types: fodder and forage. Used alone, the word ''feed'' more often refers to fodder. Animal feed is an important input to ...
, alongside direct
grazing In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
of maize grown for this purpose. File:Corn By-Product Used for Livestock Feed.jpg, Cattle wait alongside a fence as a truck distributes a grain feed composed of corn by-products into troughs. File:Bales from corn stems 01.jpg, Baled cornstalks


Chemicals

Starch from maize can be made into
plastics Plastics are a wide range of synthetic polymers, synthetic or semi-synthetic materials that use polymers as a main ingredient. Their Plasticity (physics), plasticity makes it possible for plastics to be Injection moulding, moulded, Extrusion, e ...
,
fabric Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, different fabric types, etc. At first, the word "textiles" only referred to woven fabrics. However, weaving is not the ...
s,
adhesive Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...
s, and many other chemical products.
Corn steep liquor Corn steep liquor is a by-product of corn wet-milling. A viscous concentrate of corn solubles which contains amino acids, vitamins and minerals, it is an important constituent of some growth media. It was used in the culturing of ''Penicillium'' dur ...
, a plentiful watery byproduct of maize
wet milling Wet-milling is a process in which feed material is steeped in water, with or without sulfur dioxide, to soften the seed kernel in order to help separate the kernel’s various components. For example, wet-milling plants can separate a 56-pound bu ...
process, is used in the biochemical industry and research as a culture medium to grow
microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s.


Biofuel

Feed maize is being used for heating; specialized corn stoves (similar to wood stoves) use either feed maize or wood pellets to generate heat. Maize cobs can be used as a
biomass Biomass is plant-based material used as a fuel for heat or electricity production. It can be in the form of wood, wood residues, energy crops, agricultural residues, and waste from industry, farms, and households. Some people use the terms bi ...
fuel source. Home-heating furnaces which use maize kernels as a fuel have a large hopper that feeds the kernels into the fire. Maize is used as a feedstock for the production of
ethanol fuel Ethanol fuel is ethyl alcohol, the same type of alcohol found in alcoholic beverages, used as fuel. It is most often used as a motor fuel, mainly as a biofuel additive for gasoline. The first production car running entirely on ethanol was the ...
. The price of food is indirectly affected by the use of maize for biofuel production: use of maize for biofuel production increases the demand, and therefore the price of maize. A pioneering
biomass gasification Gasification is a process that converts biomass- or fossil fuel-based carbonaceous materials into gases, including as the largest fractions: nitrogen (N2), carbon monoxide (CO), hydrogen (H2), and carbon dioxide (). This is achieved by reactin ...
power plant in Strem,
Burgenland Burgenland (; hu, Őrvidék; hr, Gradišće; Austro-Bavarian: ''Burgnland;'' Slovene: ''Gradiščanska'') is the easternmost and least populous state of Austria. It consists of two statutory cities and seven rural districts, with a total of ...
, Austria, started operating in 2005. It would be possible to create
diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engin ...
from the biogas by the
Fischer Tropsch Fischer is a German occupational surname, meaning fisherman. The name Fischer is the fourth most common German surname. The English version is Fisher. People with the surname A * Abraham Fischer (1850–1913) South African public official * Ad ...
method. File:Haase anaerobic digester.JPG, Farm-based maize silage
digester A digester (alternative: digestor) is a huge vessel where chemical or biological reactions are carried out. These are used in different types of process industries. Processes where digesters are used * Anaerobic digestion * Bayer process * Kraft ...
near
Neumünster Neumünster () is a city in the middle of Schleswig-Holstein, Germany. With more than 79,000 registered inhabitants, it is the fourth-largest municipality in Schleswig-Holstein (behind Kiel, Lübeck and Flensburg). History The city was fi ...
, Germany, 2007, using whole maize plants, not just the grain. The green tarpaulin top cover is held up by the biogas stored in the digester.


In human culture

In Mesoamerica, maize is seen as a vital force, personified as a
maize god Like other Mesoamerican peoples, the traditional Maya civilization, Maya recognize in their staple crop, maize, a vital force with which they strongly identify. This is clearly shown by their mythological traditions. According to the 16th-century P ...
, usually female. In the United States, maize ears are carved into column capitals in the
United States Capitol The United States Capitol, often called The Capitol or the Capitol Building, is the seat of the legislative branch of the United States federal government, which is formally known as the United States Congress. It is located on Capitol Hill ...
building. The
Corn Palace The Corn Palace, commonly advertised as The World's Only Corn Palace and the Mitchell Corn Palace, is a multi-purpose arena/facility located in Mitchell, South Dakota, United States. The Moorish Revival building is decorated with crop art; the mu ...
in Mitchell, South Dakota, uses cobs and ears of colored maize to implement a mural design that is recycled annually. The concrete ''
Field of Corn ''Field of Corn (with Osage Orange Trees)'' is a field of concrete corn in Dublin, Ohio, publicly funded art installation in the city of Dublin, Ohio. The installation consists of 109 concrete ears of corn positioned in rows and standing upright ...
'' sculpture in
Dublin, Ohio Dublin is a city in Franklin, Delaware and Union counties in the U.S. state of Ohio. The population was 49,328 in the 2020 census with a census estimate of 49,037 in 2019. Dublin is a suburb of Columbus. The city of Dublin hosts the yearly Mem ...
depicts hundreds of ears of corn in a grassy field. A maize stalk with two ripe ears is depicted on the
reverse Reverse or reversing may refer to: Arts and media * ''Reverse'' (Eldritch album), 2001 * ''Reverse'' (2009 film), a Polish comedy-drama film * ''Reverse'' (2019 film), an Iranian crime-drama film * ''Reverse'' (Morandi album), 2005 * ''Reverse'' ...
of the Croatian 1
lipa Lipa or LIPA (Cyrillic: Липа) may refer to: Acronym *Liquid Isopropyl alcohol *League for Independent Political Action, a former American progressive political organization *Liverpool Institute for Performing Arts, a performing arts school in ...
coin, minted since 1993.Croatian National Bank
: ttp://www.hnb.hr/novcan/kovanice/e1lipa.htm?tsfsg=dd58a2499ab048a6770b27c3017b7ec2 1 Lipa Coin. Retrieved on March 31, 2009.
File:Mochica Corn.jpg, Maize sculpture, Moche culture, 300 AD,
Larco Museum The Larco Museum (officially known as Rafael Larco Herrera Archaeological Museum, in es, Museo Arqueológico Rafael Larco Herrera, links=no) is a privately owned museum of pre-Columbian art, located in the Pueblo Libre District of Lima, Peru. The ...
,
Lima Lima ( ; ), originally founded as Ciudad de Los Reyes (City of The Kings) is the capital and the largest city of Peru. It is located in the valleys of the Chillón River, Chillón, Rímac River, Rímac and Lurín Rivers, in the desert zone of t ...
, Peru File:Mayan - Stucco Portrait Head - Walters 20092026 - Three Quarter Right.jpg, Stucco head of the
Maya maize god Like other Mesoamerican peoples, the traditional Maya civilization, Maya recognize in their staple crop, maize, a vital force with which they strongly identify. This is clearly shown by their mythological traditions. According to the 16th-century P ...
from Campeche, Mexico, 550–850 AD File:Young Corn God MET DT9945.jpg,
Jaina Island Jaina Island is a pre-Columbian Maya archaeological site in the present-day Mexican state of Campeche. A small limestone island on the Yucatán Peninsula's Gulf coast with only a tidal inlet separating it from the mainland, Jaina served as an elite ...
ceramic statuette of the young
Maya maize god Like other Mesoamerican peoples, the traditional Maya civilization, Maya recognize in their staple crop, maize, a vital force with which they strongly identify. This is clearly shown by their mythological traditions. According to the 16th-century P ...
emerging from an ear of corn, 600–900 AD File:CornWaterTower.JPG,
Water tower A water tower is an elevated structure supporting a water tank constructed at a height sufficient to pressurize a water distribution system, distribution system for potable water, and to provide emergency storage for fire protection. Water towe ...
in
Rochester, Minnesota Rochester is a city in the U.S. state of Minnesota and the county seat of Olmsted County. Located on rolling bluffs on the Zumbro River's south fork in Southeast Minnesota, the city is the home and birthplace of the renowned Mayo Clinic. Acco ...
being painted as an ear of maize


See also

*
Detasseling Detasseling corn is removing the pollen-producing flowers, the tassel, from the tops of corn (maize) plants and placing them on the ground. It is a form of pollination control,List of sweetcorn varieties This is a list of the most commonly cultivated varieties of sweet corn, and the approximate number of days from germination of corn plant to harvest. Unless otherwise noted with the term ''open pollinated,'' all varieties are hybrids. Genetic ...
*
Post-harvest losses (grains) Grains may be lost in the pre-harvest, harvest, and post-harvest stages. Pre-harvest losses occur before the process of harvesting begins, and may be due to insects, weeds, and rusts. Harvest losses occur between the beginning and completion of ...
*
Push–pull technology Push–pull may refer to: In electronic technology *Push–pull output, type of electronic circuit * Push–pull converter, in electronics, is a type of DC to DC converter that uses a transformer * Push–pull connector, an electronic cable conne ...
, pest control strategy for maize and
sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many othe ...
*
Zein Zein is a class of prolamine protein found in maize (corn). It is usually manufactured as a powder from corn gluten meal. Zein is one of the best understood plant proteins.Momany, Frank A.; Sessa, David J.; Lawton, John C.; Selling, Gordon W.; H ...


References


Further reading

* Byerlee, Derek. "The globalization of hybrid maize, 1921–70." ''
Journal of Global History The ''Journal of Global History'' is a triannual peer-reviewed academic history journal covering the study of comparative, world, and global history. It was established in 2006 and is published by Cambridge University Press. The editor-in-chief ...
'' 15.1 (2020): 101–122. * Clampitt, Cynthia. ''Maize: How Corn Shaped the U.S. Heartland'' (2015) *


External links


Maize Genetics and Genomics Database

Maize Genetics Cooperation Stock Center
* {{Authority control
Maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
Zea (plant) Agriculture in Mesoamerica Crops originating from Mexico Demulcents Energy crops Flora of Mexico Flora of Guatemala Fruit vegetables Grasses of Mexico Plant models Pre-Columbian Native American cuisine Post-Columbian Native American cuisine Pre-Columbian Southwest cuisine Staple foods Tropical agriculture Taxa named by Carl Linnaeus Plants described in 1753 Symbols of Illinois