Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (
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 ...
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 ...
first domesticated by
indigenous peoples
Indigenous peoples are culturally distinct ethnic groups whose members are directly descended from the earliest known inhabitants of a particular geographic region and, to some extent, maintain the language and culture of those original people ...
in southern Mexico about 10,000 years ago. The leafy stalk of the plant produces
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 gametop ...
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 ...
s (or "tassels") and separate ovuliferous inflorescences called ears that when fertilized yield kernels or seeds, which are
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...
s. The term ''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 contra ...
because it refers specifically to this one grain, unlike ''corn'', which has a complex variety of meanings that vary by context and geographic region.
Maize 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 (nutrition), diet for a given person or group of people, supplying a large fraction 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 archaeolog ...
or
rice
Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly '' Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and ''Porteresia'', both wild and domestica ...
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 soup ...
and
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 soften ...
popcorn
Popcorn (also called popped corn, popcorns or pop-corn) is a variety of corn kernel which expands and puffs up when heated; the same names also refer to the foodstuff produced by the expansion.
A popcorn kernel's strong hull contains the se ...
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 m ...
. Sugar-rich varieties called sweet corn are usually grown for human consumption as kernels, while field corn varieties are used for animal feed, various corn-based human food uses (including grinding into cornmeal or masa, pressing into corn oil, fermentation and distillation into alcoholic beverages like bourbon whiskey), and as feedstocks for the chemical industry. Maize is also used in making
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a h ...
and other biofuels.
Maize is widely cultivated throughout the world, and a greater weight of maize is produced each year than any other grain. In 2021, total world production was 1.2 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. Maize is the most widely grown grain
crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydropo ...
Maize is a cultigen; human intervention is required for it to propagate. Whether or not the kernels fall off the cob on their own is a key piece of evidence used in archaeology to distinguish domesticated maize from its naturally-propagating teosinte ancestor. Genetic evidence can also be used to determine when various lineages split.
Most historians believe maize was domesticated in the Tehuacán Valley of Mexico. Recent research in the early 21st century has modified this view somewhat; scholars now indicate the adjacent
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 as the center of domestication.
An 2002 study by Matsuoka ''et al.''. has demonstrated that, rather than the multiple independent domestications model, all maize arose from a single domestication in southern Mexico about 9,000 years ago. The study also demonstrated that the oldest surviving maize types are those of the Mexican highlands. Later, maize spread from this region over the Americas along two major paths. This is consistent with a model based on the archaeological record suggesting that maize diversified in the highlands of Mexico before spreading to the lowlands.
Archaeologist Dolores Piperno has said:
Since then, even earlier dates have been published.
According to a genetic study by the Brazilian Agricultural Research Corporation (Embrapa), corn cultivation was introduced in South America from Mexico, in two great waves: the first, more than 6000 years ago, spread through the
Andes
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 ...
. Evidence of cultivation in Peru has been found dating to about 6700 years ago. The second wave, about 2000 years ago, through the lowlands of South America.
The earliest maize plants grew only small, corn ears, and only one per plant. In Jackson Spielvogel's view, many centuries of artificial selection (rather than the current view that maize was exploited by interplanting with '' teosinte'') by the indigenous people of the Americas resulted in the development of maize plants capable of growing several ears per plant, which were usually several centimetres/inches long each. 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 ...
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 popu ...
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. It was believed that beginning about 2500 BC, the crop spread through much of the Americas. Research of the 21st century has established even earlier dates. The region developed a trade network based on surplus and varieties of maize crops.
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 s ...
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 (nutrition), diet for a given person or group of people, supplying a large fraction of ...
of most Mapuches, "specially in the southern and coastal apucheterritories where maize did not reach maturity". 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 adm ...
maize was traded and transported as far south as 40°19' S in Melinquina, Lácar Department. In that location maize remains were found inside pottery dated to 730 ± 80 BP and 920 ± 60 BP. Probably this maize was brought across the Andes from Chile. The presence of maize in
Guaitecas Archipelago
Guaitecas Archipelago is a sparsely populated archipelago in the Aisén region of Chile. The archipelago is made up of eight main islands and numerous smaller ones. The eight largest islands are from northwest to southeast: Gran Guaiteca, Ascen ...
(43°55' S), the southernmost outpost of pre-Hispanic agriculture, is reported by early Spanish explorers. However the Spanish may have misidentified the plant.
By at least 1000 BCE, 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 ...
in
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 ...
had based their calendar, language, myths and worldview with maize at the center of their symbolism.
Columbian exchange
After the arrival of Europeans in 1492, Spanish settlers consumed maize, and explorers and traders carried it back to Europe and introduced it to other countries. 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 archaeolog ...
bread to maize,
cassava
''Manihot esculenta'', commonly called cassava (), manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America. Although a perennial plant, cassava is extensively cultivated a ...
, or potatoes. 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'' (Χρ ...
belief 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 ...
and be transformed into the body of Christ. Some Spaniards worried that by eating indigenous foods, which they did not consider nutritious, they would weaken and risk turning into Indians. "In the view of Europeans, it was the food they ate, even more than the environment in which they lived, that gave Amerindians and Spaniards both their distinctive physical characteristics and their characteristic personalities." Despite these worries, Spaniards did consume maize.
Archeological evidence
Archaeology or archeology is the scientific study of human activity through the recovery and analysis of material culture. The archaeological record consists of artifacts, architecture, biofacts or ecofacts, sites, and cultural landsca ...
from Florida sites indicate they cultivated it as well.Earle, ''The Body of the Conquistador'', p. 144.
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.
Widespread cultivation most likely began in southern Spain in 1525, after which it quickly spread to the rest of the
Spanish Empire
The Spanish Empire ( es, link=no, Imperio español), also known as the Hispanic Monarchy ( es, link=no, Monarquía Hispánica) or the Catholic Monarchy ( es, link=no, Monarquía Católica) was a colonial empire governed by Spain and its prede ...
including its territories in Italy (and, from there, to other Italian states). Maize had many advantages over wheat and barley; it yielded two and a half times the food energy per unit cultivated area, could be harvested in successive years from the same plot of land, and grew in wildly varying altitudes and climates, from relatively dry regions with only of annual rainfall to damp regions with over . By the 17th century it was a common peasant food in Southwestern Europe, including Portugal, Spain, southern France, and Italy. By the 18th century, it was the chief food of the southern French and Italian peasantry, especially in the form of
polenta
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.
Names
The word ''maize'' derives from the Spanish form of the indigenous
Taíno
The Taíno were a historic 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 late 15th century, they were the pri ...
word for the plant, ''mahiz''. Using the maize common name, Linnaeus included it as the species epithet in ''Zea mays''. It is known by other names including "corn" in some English speaking countries.
''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 contra ...
because it refers specifically to this one grain, unlike ''corn'', which has a complex variety of meanings that vary by context and geographic region. International groups such as the Centre for Agriculture and Bioscience International also consider maize the preferred common name. According to Ohio State University, the US and a handful of other English-speaking countries primarily use corn, but the rest of the world calls this maize or maíz. The word maize is considered interchangeable with corn in the West; during early British and American trade, all grains were considered corn. Maize retained the name corn in the West as the primary grain in these trade relationships.
The word "corn" outside the US, Canada, Australia, and New Zealand is synonymous with
grain
A grain is a small, hard, dry fruit ( caryopsis) – with or without an attached hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and legu ...
referring to any
cereal
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 foo ...
crop with its meaning understood to vary geographically to refer to the local
staple
Staple may refer to:
*Staple food, a foodstuff that forms the basic constituent of a diet
*Staple (fastener), a small formed metal fastener
**Surgical staple
Arts, entertainment, and media
* Staple (band), a Christian post-hardcore band
** ''Stap ...
. In the United States, Canada, Australia, and New Zealand, ''corn'' primarily means maize; this usage started as a shortening of "Indian corn". "Indian corn" primarily means maize (the staple grain of
indigenous Americans
Native Americans or Native American may refer to:
Ethnic groups
* Indigenous peoples of the Americas, the pre-Columbian peoples of North and South America and their descendants
* Native Americans in the United States
* Indigenous peoples in Can ...
), but can refer more specifically to multicolored " flint corn" used for decoration. Other common names include barajovar, makka, silk maize, and zea.
In a 1999 journal article, Betty Fussell describing calling maize as corn was "to plunge into tragi-farcial mistranslations of language and history." Similar to the British, the Spanish referred to maize as panizo, a generic term for cereal grains, as did Italians with the term polenta. The British later referred to maize as Turkey wheat, Turkey corn, or Indian corn with Fusell commenting that "they meant not a place but a condition, a savage rather than a civilized grain", especially with
Turkish people
The Turkish people, or simply the Turks ( tr, Türkler), are the world's largest Turkic ethnic group; they speak various dialects of the Turkish language and form a majority in Turkey and Northern Cyprus. In addition, centuries-old ethnic Tu ...
later naming it kukuruz, or barbaric.
The word ''maize'' is used by agricultural bodies and research institutes such as the UN's FAO, 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 ...
based out of Mexico, and the Indian Institute of Maize Research. National agricultural and industry associations often include the word ''maize'' in their name such as the Maize Association of Australia, and the National Maize Association of Nigeria.
In Southern Africa, maize is commonly called ''mielie'' (
Afrikaans
Afrikaans (, ) is a West Germanic language that evolved in the Dutch Cape Colony from the Dutch vernacular of Holland proper (i.e., the Hollandic dialect) used by Dutch, French, and German settlers and their enslaved people. Afrikaans g ...
) or ''mealie'' (English), words possibly derived from the Portuguese word for maize, ''milho'', but more probably from Dutch ''meel'' or English ''meal'', meaning the edible part of a grain or pulse.
Structure and physiology
The maize plant is often in height, though some natural strains can grow , and the tallest recorded plant reached almost . The stem is commonly composed of 20 internodes of length. The leaves arise from the nodes, alternately on opposite sides on the stalk, and have entire margins.
The apex of the stem ends in 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 ...
of male flowers. When the tassel is mature and conditions are suitably warm and dry, anthers on the tassel dehisce and release pollen. Maize pollen is anemophilous (dispersed by wind), and because of its large settling velocity, most pollen falls within a few meters of the tassel.
Ears develop above a few of the leaves in the midsection of the plant, between the stem and leaf sheath, elongating by around per day, to a length of with being the maximum alleged in the subspecies. They are female
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 ...
s, tightly enveloped by several layers of ear leaves commonly called husks.
Elongated stigmas, called silks, emerge from the whorl of husk leaves at the end of the ear. They are often pale yellow and in length, like tufts of hair in appearance. At the end of each is a carpel, which may develop into a "kernel" if fertilized by a pollen grain. The pericarp of the fruit is fused with the seed coat referred to as "
caryopsis
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 f ...
", typical of the
grasses
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 a ...
, and the entire kernel is often referred to as the "
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...
". The cob is close to a multiple fruit in structure, except that the individual fruits (the kernels) never fuse into a single mass. The grains are about the size of peas, and adhere in regular rows around a white, pithy substance, which forms the cob. The maximum size of kernels is reputedly . An ear commonly holds 600 kernels. They are of various colors: blackish, bluish-gray,
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, ...
, green, red, white and yellow. When ground into
flour
Flour is a powder made by grinding raw grains, roots, beans, nuts, or seeds. Flours are used to make many different foods. Cereal flour, particularly wheat flour, is the main ingredient of bread, which is a staple food for many c ...
, maize yields more flour with much less
bran
Bran, also known as miller's bran, is the hard outer layers of cereal grain. It consists of the combined aleurone and pericarp. Corn (maize) bran also includes the pedicel (tip cap). Along with germ, it is an integral part of whole grains ...
than wheat does. It lacks the protein gluten of wheat and, therefore, makes baked goods with poor rising capability. A
genetic variant Genetic variant may refer to:
* Single-nucleotide polymorphism (SNP), in a case it is a common genetic variant
* Mutation, in a case where it is a rare genetic variant
* Copy-number variation
* Variant (biology)
See also
* Genetic variation (dis ...
that accumulates more sugar and less
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 ...
in the ear is consumed as a vegetable and is 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 m ...
. Young ears can be consumed raw, with the cob and silk, but as the plant matures (usually during the summer months), the cob becomes tougher and the silk dries to inedibility. By the end of the
growing season
A season is a division of the year marked by changes in weather, ecology, and the amount of daylight. The growing season is that portion of the year in which local conditions (i.e. rainfall, temperature, daylight) permit normal plant growth. Wh ...
, the kernels dry out and become difficult to chew without cooking.
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 ...
File:Corn blooming.jpg, Mature silk
File:GreenCorn.JPG, Stalks, ears and silk
File:Männliche Blüte einer Maispflanze 2009-08-19.JPG, Male flowers
File:ZeaMays.jpg, Full-grown maize plants
File:Klip kukuruza uzgojen u Međimurju (Croatia).JPG, Mature maize ear on a stalk
Planting density affects multiple aspects of maize. Modern farming techniques in
developed countries
A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastr ...
usually rely on dense planting, which produces one ear per stalk. Stands of silage maize are yet denser, and achieve a lower percentage of ears and more plant matter.
Maize is a facultative short-day plant and flowers in a certain number of growing degree days > in the environment to which it is adapted. The magnitude of the influence that long nights have on the number of days that must pass before maize
flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...
s is genetically prescribed and regulated by the phytochrome system. Photoperiodicity can be eccentric in tropical
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...
s such that the long days characteristic of higher latitudes allow the plants to grow so tall that they do not have enough time to produce seed before being killed by frost. These attributes, however, may prove useful in using tropical maize for biofuels.
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 a ...
). DIMBOA is a member of a group of hydroxamic acids (also known as benzoxazinoids) that serve as a natural defense against a wide range of pests, including insects, pathogenic fungi and
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
. DIMBOA is also found in related grasses, particularly wheat. A maize mutant (bx) lacking DIMBOA is highly susceptible to attack by aphids and
fungi
A fungus (plural, : fungi or funguses) is any member of the group of Eukaryote, eukaryotic organisms that includes microorganisms such as yeasts and Mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified ...
. DIMBOA is also responsible for the relative resistance of immature maize to the European corn borer (family
Crambidae
The Crambidae are the grass moth family of lepidopterans. They are variable in appearance, the nominal subfamily Crambinae (grass moths) taking up closely folded postures on grass stems where they are inconspicuous, while other subfamilies includ ...
). As maize matures, DIMBOA levels and resistance to the corn borer decline.
Because of its shallow roots, maize is susceptible to droughts, intolerant of nutrient-deficient soils, and prone to be uprooted by severe winds.
File:Ab food 06.jpg, Maize kernels
File:Maize plant diagram.svg, Maize plant diagram
File:Aa maize ear irregular 01.jpg, Ear of maize with irregular rows of kernels
While yellow maizes derive their color from
zeaxanthin
Zeaxanthin is one of the most common carotenoids in nature, and is used in the xanthophyll cycle. Synthesized in plants and some micro-organisms, it is the pigment that gives paprika (made from bell peppers), corn, saffron, goji (wolfberries), ...
, in red-colored maizes, the kernel coloration is due to
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 co ...
s and phlobaphenes. These latter substances are synthesized in the flavonoids synthetic pathway from polymerization of flavan-4-ols by the expression of maize pericarp color1 (p1) gene which encodes an R2R3 myb-like transcriptional activator of the A1 gene encoding for the dihydroflavonol 4-reductase (reducing dihydroflavonols into flavan-4-ols) while another gene (Suppressor of Pericarp Pigmentation 1 or SPP1) acts as a suppressor. The p1 gene encodes an Myb-homologous transcriptional activator of genes required for biosynthesis of red phlobaphene pigments, while the P1-wr allele specifies colorless kernel pericarp and red cobs, and unstable factor for orange1 (Ufo1) modifies P1-wr expression to confer pigmentation in kernel pericarp, as well as vegetative tissues, which normally do not accumulate significant amounts of phlobaphene pigments. The maize P gene encodes a Myb homolog that recognizes the sequence CCT/AACC, in sharp contrast with the C/TAACGG bound by vertebrate Myb proteins.
The ''ear leaf'' is the leaf most closely associated with a particular developing ear. This leaf and above contribute 70% to 75% to 90% of grain fill. Therefore fungicide application is most important in that region in most disease environments.
Abnormal flowers
Maize flowers may sometimes exhibit mutations that lead to the formation of female flowers in the tassel. These mutations, ''ts4'' and ''Ts6'', prohibit the development of the stamen while simultaneously promoting pistil development. This may cause
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 ...
s containing both male and female flowers, or
hermaphrodite
In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes.
Many taxonomic groups of animals (mostly invertebrates) do not have ...
flowers.
Genetics
Maize is an annual grass in the family Gramineae, which includes such plants as
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 archaeolog ...
,
rye
Rye (''Secale cereale'') is a grass grown extensively as a grain, a cover crop and a forage crop. It is a member of the wheat tribe (Triticeae) and is closely related to both wheat (''Triticum'') and barley (genus ''Hordeum''). Rye grain is u ...
,
barley
Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley ...
,
rice
Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly '' Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and ''Porteresia'', both wild and domestica ...
,
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 ot ...
, and sugarcane. There are two major species of the genus '' Zea'' (out of six total): ''Z. mays'' (maize) and '' Z. diploperennis'', which is a
perennial
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...
type of teosinte. The annual teosinte variety called '' Z. m. mexicana'' is the closest botanical relative to maize. It still grows in the wild as an annual in Mexico and Guatemala.
Many forms of maize are used for food, sometimes classified as various subspecies related to the amount of starch each has:
* Flour corn: ''Z. m.'' var. ''amylacea''
*
Popcorn
Popcorn (also called popped corn, popcorns or pop-corn) is a variety of corn kernel which expands and puffs up when heated; the same names also refer to the foodstuff produced by the expansion.
A popcorn kernel's strong hull contains the se ...
: ''Z. m.'' var. ''everta''
* Dent corn : ''Z. m.'' var. ''indentata''
* Flint corn: ''Z. m.'' var. ''indurata''
*
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 m ...
: ''Z. m.'' var. ''saccharata'' and ''Z. m.'' var. ''rugosa''
* Waxy corn: ''Z. m.'' var. ''ceratina''
* Amylomaize: ''Z. mays''
* Pod corn: ''Z. m.'' var. ''tunicata'' Larrañaga ex A. St. Hil.
* Striped maize: ''Z. m.'' var. ''japonica''
This system has been replaced (though not entirely displaced) over the last 60 years by multivariable classifications based on ever more data. Agronomic data were supplemented by botanical traits for a robust initial classification, then genetic,
cytological
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living a ...
, protein and DNA evidence was added. Now, the categories are forms (little used), races, racial complexes, and recently branches.
Maize is a
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, respecti ...
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 ar ...
s (n=10). The combined length of the chromosomes is 1500 cM. Some of the maize chromosomes have what are known as "chromosomal knobs": highly repetitive heterochromatic domains that stain darkly. Individual knobs are polymorphic among strains of both maize and teosinte.
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 ...
used these knob markers 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. Transp ...
theory of "jumping genes", for which she won the 1983
Nobel Prize in Physiology or Medicine
The Nobel Prize in Physiology or Medicine ( sv, Nobelpriset i fysiologi eller medicin) is awarded yearly by the Nobel Assembly at the Karolinska Institute, Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or ...
. Maize is still an important model organism 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, asexual reproduction, metamorphosis, and the growth and differentiation of ste ...
today.
The
centromere
The centromere links a pair of sister chromatids together during cell division. This constricted region of chromosome connects the sister chromatids, creating a short arm (p) and a long arm (q) on the chromatids. During mitosis, spindle fibers ...
s have two types of structural components, both of which are found only in the centromeres: Large arrays of CentC, a short satellite DNA; and a few of a family of retrotransposons. The B chromosome, unlike the others, contains an additional repeat which extends into neighboring areas of the chromosome. Centromeres can accidentally shrink during division and still function, although it is thought this will fail if it shrinks below a few hundred kilobase.
Kinetochore
A kinetochore (, ) is a disc-shaped protein structure associated with duplicated chromatids in eukaryotic cells where the spindle fibers attach during cell division to pull sister chromatids apart. The kinetochore assembles on the centromere ...
s contain RNA originating from centromeres. Centromere regions can become inactive, and can continue in that state if the chromosome still has another active one.
The Maize Genetics Cooperation Stock Center, funded by the USDA Agricultural Research Service and located in the Department of Crop Sciences at the
University of Illinois at Urbana-Champaign
The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the Uni ...
, is a stock center of maize mutants. The total collection has nearly 80,000 samples. The bulk of the collection consists of several hundred named genes, plus additional gene combinations and other heritable variants. There are about 1000 chromosomal aberrations (e.g., translocations and inversions) and stocks with abnormal chromosome numbers (e.g., tetraploids). Genetic data describing the maize mutant stocks as well as myriad other data about maize genetics can be accessed a MaizeGDB the Maize Genetics and Genomics Database.
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 ...
(NSF), Department of Agriculture (
USDA
The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...
) and the Department of Energy (DOE) formed a consortium to sequence the B73 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 ...
. 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. Sequences and genome annotations have also been made available throughout the project's lifetime at the project's official site.
Primary sequencing of the maize genome was completed in 2008. On November 20, 2009, the consortium published results of its sequencing effort in ''Science''. 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. Transp ...
s, was found to contain 32,540 genes (By comparison, the
human genome
The human genome is a complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria. These are usually treated separately as the ...
contains about 2.9 billion bases and 26,000 genes). Much of the maize genome has been duplicated and reshuffled by helitrons—group of rolling circle transposons.
In ''Z. mays'' and various other angiosperms the MADS-box motif is involved in floral development. Early study in several angiosperm models including ''Z. mays'' was the beginning of research into the molecular evolution of floral structure in general, as well as their role in nonflowering plants.
Varieties differ in their resistance to insects, including borers.CIMMYT maintains a large collection of maize/corn accessions tested and cataloged for insect resistance.
Evolution
As with many plants and animals, ''Z. mays'' has a positive correlation between
effective population size
The effective population size (''N'e'') is a number that, in some simplified scenarios, corresponds to the number of breeding individuals in the population. More generally, ''N'e'' is the number of individuals that an idealised population w ...
and the magnitude of
selection pressure
Any cause that reduces or increases reproductive success in a portion of a population potentially exerts evolutionary pressure, selective pressure or selection pressure, driving natural selection. It is a quantitative description of the amount of ...
. ''Z. m.'' having an EPS of ~650,000, it clusters with others of about the same EPS, and has 79% of its
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha ...
sites under selection.Recombination is a significant source of diversity in ''Z. mays''. (Note that this finding supersedes previous studies which showed no such correlation.)
This recombination/diversity effect is seen throughout plants but is also found to not occur – or not as strongly – in regions of high gene density. This is likely the reason that domesticated ''Z. mays'' has not seen as much of an increase in diversity within areas of higher density as in regions of lower density, although there is more evidence in other plants.
Some lines of maize have undergone ancient polyploidy events, starting 11m years ago. Over that time ~72% of polyploid duplicated genes have been retained, which is higher than other plants with older polyploidy events. Thus maize ''may'' be due to lose more duplicate genes as time goes along, similar to the course followed by the genomes of other plants. If so - if gene loss has merely not occurred yet - that could explain the lack of observed
positive selection
In population genetics, directional selection, is a mode of negative natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype. Under dir ...
and lower negative selection which are observed in otherwise similar plants, i.e. also naturally outcrossing and with similar effective population sizes.
Ploidy does not appear to influence EPS or magnitude of selection effect in maize.
Breeding
Maize reproduces sexually each year. This randomly selects half the genes from a given plant to propagate to the next generation, meaning that desirable traits found in the crop (like high yield or good nutrition) can be lost in subsequent generations unless certain techniques are used.
Maize breeding in prehistory resulted in large plants producing large ears. Modern breeding began with individuals who selected highly productive varieties in their fields and then sold seed to other farmers. James L. Reid was one of the earliest and most successful developing Reid's Yellow Dent in the 1860s. These early efforts were based on mass selection. Later breeding efforts included ear to row selection (C. G. Hopkins c. 1896), hybrids made from selected inbred lines (G. H. Shull, 1909), and the highly successful double cross hybrids using four inbred lines (
D. F. Jones
Dennis Feltham Jones (15 July 1918 – 1 April 1981) was a British science fiction author who published under the name D.F. Jones. He was a Royal Navy commander during World War II and lived in Cornwall.
His first novel, ''Colossus'' (1966), a ...
c. 1918, 1922). University supported breeding programs were especially important in developing and introducing modern hybrids. By the 1930s, companies such as Pioneer devoted to production of hybrid maize had begun to influence long-term development. Internationally important seed banks such as the
International Maize and Wheat Improvement Center
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) and the US bank at the Maize Genetics Cooperation Stock Center
University of Illinois at Urbana-Champaign
The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the Uni ...
maintain germplasm important for future crop development.
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 which are the source of the " baby corn" 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 wit ...
.
CIMMYT operates a conventional breeding program to provide optimized strains. The program began in the 1980s. Hybrid seeds are distributed in Africa by the Drought Tolerant Maize for Africa project.
Genetic engineering
Genetically engineered(GE) maize was one of the 26 GE crops grown commercially in 2016. The vast majority of this is Bt maize. Grown since 1997 in the United States and Canada, 92% of the US maize crop was genetically modified in 2016 and 33% of the worldwide maize crop was GM in 2016. As of 2011, Herbicide-tolerant maize varieties were grown in Argentina, Australia, Brazil, Canada, China, Colombia, El Salvador, the European Union, Honduras, Japan, Korea, Malaysia, Mexico, New Zealand, Philippines, the Russian Federation, Singapore, South Africa, Taiwan, Thailand, and the United States. Insect-resistant maize was grown in Argentina, Australia, Brazil, Canada, Chile, China, Colombia, Egypt, the European Union, Honduras, Japan, Korea, Malaysia, Mexico, New Zealand, Philippines, South Africa, Switzerland, Taiwan, the United States, and Uruguay.
In September 2000, up to $50 million worth of food products were recalled due to the presence of Starlink genetically modified corn, which had been approved only for animal consumption and had not been approved for human consumption, and was subsequently withdrawn from the market.
For pest and disease resistance
Tropical landraces remain an important and underused source of resistance alleles for disease and for herbivores. Notable discoveries of rare alleles for this purpose were made by Dao ''et al.'', 2014 and Sood ''et al.'', 2014. Rashid ''et al.'', 2018 use an association mapping panel from CIMMYT originally developed for tropical drought tolerance traits to find new genomic 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 SDMR regions already located by others. .
Origin
Maize is the domesticated variant of teosinte.
* 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'', ).
Several theories had been proposed about the specific origin of maize in Mesoamerica:
# It is a direct
domestication
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 ...
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 south-eastern Mexico, with up to 12% of its genetic material obtained from ''Z. m.'' ssp. ''mexicana'' through introgression.
# It has been derived from hybridization between a small domesticated maize (a slightly changed form of a wild maize) and a teosinte of section ''Luxuriantes'', either ''Z. luxurians'' or '' Z. diploperennis''.
# It has undergone two or more domestications either of a wild maize or of a teosinte. (The term "teosinte" describes all
species
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
and subspecies in the genus ''Zea'', excluding ''Z. m.'' ssp. ''mays''.)
# It has evolved from a hybridization of ''Z. diploperennis'' by ''
Tripsacum dactyloides
''Tripsacum dactyloides'', commonly called eastern gamagrass, or Fakahatchee grass, is a warm-season, sod-forming bunch grass. It is widespread in the Western Hemisphere, native from the eastern United States to northern South America.
''.
In the late 1930s, Paul Mangelsdorf suggested that domesticated maize was the result of a hybridization event between an unknown wild maize and a species of '' Tripsacum'', a related genus. This theory about the origin of maize has been refuted by modern genetic testing, which refutes Mangelsdorf's model and the fourth listed above.
The teosinte origin theory was proposed by the Russian botanist Nikolai Ivanovich Vavilov in 1931 and the later 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." Alfre ...
-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 e ...
in 1932. It is supported experimentally and by recent studies of the plants' genomes. Teosinte and maize can cross-breed and produce fertile offspring. A number of questions remain concerning the species, among them:
# how the immense diversity of the species of sect. ''Zea'' originated,
# how the tiny archaeological specimens of 3500–2700 BC could have been selected from a teosinte, and
# how domestication could have proceeded without leaving remains of teosinte or maize with teosintoid traits earlier than the earliest known until recently, dating from ca. 1100 BC.
The
domestication
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 ...
of maize is of particular interest to researchers— archaeologists, geneticists, ethnobotanists, geographers, etc. The process is thought by some to have started 7,500 to 12,000 years ago. Research from the 1950s to 1970s originally focused on the hypothesis that maize domestication occurred in the highlands between the states of
Jalisco
Jalisco (, , ; Nahuatl: Xalixco), officially the Free and Sovereign State of Jalisco ( es, Estado Libre y Soberano de Jalisco ; Nahuatl: Tlahtohcayotl Xalixco), is one of the 31 states which, along with Mexico City, comprise the 32 Federal ...
, because the oldest archaeological remains of maize known at the time were found there.
Connection with 'parviglumis' subspecies
Genetic studies, published in 2004 by
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 ...
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, and also known as Balsas teosinte, as being the crop wild relative that is genetically most similar to modern maize. This was confirmed by further studies, which refined this hypothesis somewhat. Archaeobotanical studies, published in 2009, point to the middle part of the Balsas River valley as the likely location of early domestication; this river is not very long, so these locations are not very distant. Stone milling tools with maize residue have been found in an 8,700 year old layer of deposits in a cave not far from
Iguala, Guerrero
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 was part of the team that first published, in 2002, that maize had been domesticated only once, about 9,000 years ago, and then spread throughout the Americas.
A primitive corn was being grown in southern Mexico, Central America, and northern South America 7,000 years ago. Archaeological remains of early maize ears, found at Guila Naquitz Cave in the Oaxaca Valley, date back roughly 6,250 years; the oldest ears from caves near Tehuacan, Puebla, 5,450 B.P.
Maize pollen dated to 7,300 B.P. from San Andres, Tabasco, on the Caribbean coast has also been recovered.
As maize was introduced to new cultures, new uses were developed and new varieties selected to better serve in those preparations. Maize was the staple food, or a major staple – along with squash, Andean region
potato
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 Un ...
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 ...
– of most
pre-Columbian
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, ...
North American, Mesoamerican, South American, and Caribbean cultures. The Mesoamerican civilization, in particular, was deeply interrelated with maize. Its traditions and rituals involved all aspects of maize cultivation – from the planting to the food preparation. Maize formed the Mesoamerican people's identity.
It is unknown what precipitated its domestication, because the edible portion of the wild variety is too small, and hard to obtain, to be eaten directly, as each kernel is enclosed in a very hard bivalve shell.
In 1939, George Beadle demonstrated that the kernels of teosinte are readily "popped" for human consumption, like modern popcorn. Some have argued it would have taken too many generations of
selective breeding
Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant ma ...
to produce large, compressed ears for efficient cultivation. However, studies of the hybrids readily made by intercrossing teosinte and modern maize suggest this objection is not well founded.
Spreading to the north
Around 4,500 ago, maize began to spread to the north; it was first cultivated in what is now the United States at several sites in New Mexico and Arizona, about 4,100 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.
In 2005, research by the
USDA
The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...
Forest Service suggested that the rise in maize cultivation 500 to 1,000 years ago in what is now the southeastern United States corresponded with a decline of freshwater
mussel
Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, whic ...
s, which are very sensitive to environmental changes.
Cultivation
Planting
Because it is cold-intolerant, in the temperate zones 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 C4 carbon fixation, maize is a considerably more water-efficient crop than plants that use C3 carbon fixation such as alfalfa and soybeans. Maize is most sensitive to drought at the time of silk emergence, when the flowers are ready for pollination. In the United States, a good harvest was traditionally predicted if the maize was "knee-high by the
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 State ...
", although modern hybrids generally exceed this growth rate. Maize used for silage is harvested while the plant is green and the fruit immature. Sweet corn is harvested in the "milk stage", after pollination but before starch has formed, between late summer and early to mid-autumn. Field maize is left in the field until very late in the autumn to thoroughly dry the grain, and may, in fact, sometimes not be harvested until winter or even early spring. The importance of sufficient soil moisture is shown in many parts of Africa, where periodic
drought
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, population imbalance, widespread poverty, an economic catastrophe or government policies. This phenomenon is usually accom ...
. Although it is grown mainly in wet, hot climates, it has been said to thrive in cold, hot, dry or wet conditions, meaning that it is an extremely versatile crop.
Maize was planted by the Native Americans in hills, in a complex system known to some as the Three Sisters. Maize provided support for beans, and the beans provided nitrogen derived from nitrogen-fixing rhizobia 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 fo ...
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. This method was replaced by single species hill planting where each hill apart was planted with three or four seeds, a method still used by home gardeners. A later technique was "checked maize", where hills were placed apart in each direction, allowing cultivators to run through the field in two directions. In more arid lands, this was altered and seeds were planted in the bottom of deep furrows to collect water. Modern technique plants maize in rows which allows for cultivation while the plant is young, although the hill technique is still used in the maize fields of some Native American reservations. When maize is planted in rows, it also allows for planting of other crops between these rows to make more efficient use of land space.
In most regions today, maize grown in residential
garden
A garden is a planned space, usually outdoors, set aside for the cultivation, display, and enjoyment of plants and other forms of nature. The single feature identifying even the wildest wild garden is ''control''. The garden can incorporate bot ...
s is still often planted manually with a
hoe
Hoe or HOE may refer to:
* Hoe (food), a Korean dish of raw fish
* Hoe (letter), a Georgian letter
* Hoe (tool), a hand tool used in gardening and farming
** Hoe-farming, a term for primitive forms of agriculture
* Backhoe, a piece of excavati ...
, whereas maize grown commercially is no longer planted manually but rather is planted with a planter. In North America, fields are often planted in a two-
crop rotation
Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. It reduces reliance on one set of nutrients, pest and weed pressure, and the probability of developing resistant ...
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 ...
s in regions with longer summers. Sometimes a third crop, winter wheat, is added to the rotation.
Many of the maize varieties grown in the United States and Canada are hybrids. Often the varieties have been genetically modified to tolerate glyphosate or to provide protection against natural pests. Glyphosate is an herbicide which kills all plants except those with genetic tolerance. This genetic tolerance is very rarely found in nature.
In the midwestern United States, low-till or no-till farming techniques are usually used. In low-till, fields are covered once, maybe twice, with a tillage implement either ahead of crop planting or after the previous harvest. The fields are planted and fertilized.
Weed
A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...
s are controlled through the use of herbicides, and no cultivation tillage is done during the growing season. This technique reduces moisture evaporation from the soil, and thus provides more moisture for the crop.
The technologies mentioned in the previous paragraph enable low-till and no-till farming. Weeds compete with the crop for moisture and nutrients, making them undesirable.
Harvesting
Maize harvested as a grain crop can be kept in the field a relatively long time, even months, after the crop is ready to harvest; it is also harvested and stored in the husk leaves if kept dry.
Before the 20th century, all maize harvesting was by
manual labour
Manual labour (in Commonwealth English, manual labor in American English) or manual work is physical work done by humans, in contrast to labour by machines and working animals. It is most literally work done with the hands (the word ''manual ...
, by
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 ...
, or by some combination of those. Whether the ears were hand-picked and 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 ...
was grazed, or the whole plant was cut, gathered, and shocked, people and
livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to anima ...
did all the work. Between the 1890s and the 1970s, the technology of maize harvesting expanded greatly. Today, all such technologies, from entirely manual harvesting to entirely mechanized, are still in use to some degree, as appropriate to each farm's needs, although the thoroughly mechanized versions predominate, as they offer the lowest unit costs when scaled to large farm operations.
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 World War II by country, vast majority of the world's countries—including all of the great power ...
, most maize in North America was harvested by hand. This involved a large number of workers and associated social events (husking or shucking bees). From the 1890s onward, some machinery became available to partially mechanize the processes, such as one- and two-row mechanical pickers (picking the ear, leaving the
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-binders designed specifically for maize (for example, ). The latter produce sheaves that can be shocked. By hand or mechanical picker, the entire ear is harvested, which then requires a separate operation of a maize sheller to remove the kernels from the ear. Whole ears of maize were often stored in
corn crib
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. T ...
s, and these whole ears are a sufficient form for some livestock feeding use. Today corn cribs with whole ears, and corn binders, are less common because most modern farms harvest the grain from the field with a
combine
Combine may refer to:
Machinery
* Combine harvester, or combine, a machine to harvest grain crops
* Combine seeder, or combine, a machine to plant seeds
Company structure
* Corporate group, an industrial business group in Western democracie ...
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 ...
. 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.
The entire maize plant is also harvested as a silage crop.
For storing grain in bins, the moisture of the grain must be sufficiently low to avoid spoiling. If the moisture content of the harvested grain is too high, grain 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 as ...
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 carbon ...
) 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.
United States
In 2016, maize production was forecast to be over 380 million metric tons (15 billion
bushel
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 agri ...
s), an increase of 11% over 2014 American production. Based on conditions as of August 2016, the expected yield would be the highest ever for the United States. The area of harvested maize was forecast to be , an increase of 7% over 2015. Maize is especially popular in Midwestern states such as
Indiana
Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th ...
,
Iowa
Iowa () is a U.S. state, state in the Midwestern United States, Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wiscon ...
, and
Illinois
Illinois ( ) is a state in the Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolitan areas include, Peoria and Roc ...
; in the latter, it was named the state's official grain in 2017.
The estimated corn usage for crop year September 1, 2020 to August 31, 2021, was 38.7 percent was used for feed, 34 percent for ethanol, 17.5 percent for export, and 9.8 percent for food.
Trade
Corn futures are traded on several exchanges, the Chicago Board of Trade (CBOT) and JSE Derivatives (JDERIV). The Chicago Board Of Trade sells corn futures with a contact size of 5000 bushels which is quoted in cents/bushel and the JDERIV has a contact size of 100 Tonnes, quoted in Rand/Ton. The detailed contract specifications are listed below:
Asian corn borer
''Ostrinia furnacalis'' is a species of moth in the family Crambidae, the grass moths. It was described by Achille Guenée in 1854 and is known by the common name Asian corn borer since this species is found in Asia and feeds mainly on corn crop ...
(''Ostrinia furnacalis'')
* Common armyworm (''
Pseudaletia unipuncta
''Mythimna unipuncta'', the true armyworm moth, white-speck moth, common armyworm or rice armyworm, is a nocturnal agricultural pest belonging to the family Noctuidae. This moth is also commonly referred to by the scientific name ''Pseudaletia un ...
'')
*
Common earwig
''Forficula auricularia'', the common earwig or European earwig, is an omnivorous insect in the family Forficulidae. The European earwig survives in a variety of environments and is a common household insect in North America. The name ''earwig'' c ...
Lesser cornstalk borer
''Elasmopalpus'' is a monotypic snout moth genus described by Émile Blanchard in 1852. Its single species, ''Elasmopalpus lignosellus'', the lesser cornstalk borer, was described by Philipp Christoph Zeller in 1852. It is found from the southern ...
(''Elasmopalpus lignosellus'')
* Maize weevil (''Sitophilus zeamais'')
* Northern armyworm, Oriental armyworm or Rice ear-cutting caterpillar ('' Mythimna separata'')
* Southwestern corn borer (''Diatraea grandiosella'')
* Stalk borer (''Papaipema nebris'')
The susceptibility of maize to the European corn borer and corn rootworms, and the resulting large crop losses which are estimated at a billion dollars worldwide for each pest, led to the development of
transgenics
A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques. The exact definition of a genetically modified organism and what constitutes genetic engineering varies, with ...
expressing the ''
Bacillus thuringiensis
''Bacillus thuringiensis'' (or Bt) is a gram-positive, soil-dwelling bacterium, the most commonly used biological pesticide worldwide. ''B. thuringiensis'' also occurs naturally in the gut of caterpillars of various types of moths and butter ...
'' toxin. "Bt maize" is widely grown in the United States and has been approved for release in Europe.
Diseases
*
Rust
Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO(OH), ...
* Corn smut or common smut (''Ustilago maydis''): a fungal disease, known in Mexico as ''huitlacoche'', which is prized by some as a gourmet delicacy in itself
* Northern corn leaf bligh (Purdue Extension site)(Pioneer site)
*
Southern corn leaf blight
Southern corn leaf blight (SCLB) is a fungal disease of maize caused by the plant pathogen ''Bipolaris maydis'' (also known as ''Cochliobolus heterostrophus'' in its
teleomorph state).
The fungus is an Ascomycete and can use conidia or ascospor ...
Stalk rot
Stalk or stalking may refer to:
Behaviour
* Stalk, the stealthy approach (phase) of a predator towards its prey
* Stalking, an act of intrusive behaviour or unwanted attention towards a person
* Deer stalking, the pursuit of deer for sport
Biolog ...
*
Ear rot
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 of ...
A. parasiticus
''Aspergillus parasiticus'' is a fungus belonging to the genus '' Aspergillus''. This species is an unspecialized saprophytic mold, mostly found outdoors in areas of rich soil with decaying plant material as well as in dry grain storage facilit ...
''
Storage
Drying is vital to prevent or at least reduce mycotoxin contamination. '' Aspergillus'' and '' Fusarium'' spp. are the most common mycotoxin sources, but there are others. Altogether maize contaminants are so common, and this crop is so economically important, that maize mycotoxins are among the most important in agriculture in general.
Uses
Human food
Maize and cornmeal (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 (nutrition), diet for a given person or group of people, supplying a large fraction of ...
in many regions of the world. Maize is used to produce cornstarch, a common ingredient in home cooking and many industrialized food products. Maize starch can be hydrolyzed and enzymatically treated to produce syrups, particularly high fructose corn syrup, a sweetener; and also fermented and distilled to produce grain alcohol. Grain alcohol from maize is traditionally the source of Bourbon whiskey. Corn flour is used to make cornbread and other baked products.
In prehistoric times
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 ...
n women used a '' metate'' to process maize into ground cornmeal, allowing the preparation of foods that were more calorie dense than popcorn. After ceramic vessels were invented the
Olmec
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 ...
people began to cook maize together with beans, improving the nutritional value of the staple meal. Although maize naturally contains niacin, an important nutrient, it was not bioavailable without the process of nixtamalization. The
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 popu ...
used nixtamal meal to make varieties of porridges and tamales. The process was later used in the
cuisine of the American South
The cuisine of the Southern United States encompasses diverse food traditions of several regions, including Tidewater, Appalachian, Lowcountry, Cajun, Creole, and Floribbean cuisine. In recent history, elements of Southern cuisine have spread t ...
to prepare corn for
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 o ...
and
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 ...
.
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 ...
chilaquiles
Chilaquiles () are a traditional Mexican breakfast dish consisting of corn tortillas cut into quarters and lightly fried.
Ingredients and variations
Typically, corn tortillas cut into quarters and lightly fried or baked for a lighter version ...
, enchiladas, tostadas and many more. In Mexico the fungus of maize, known as huitlacoche, is considered a 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'' 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 ...
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 o ...
in the South) 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 flour ...
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. These are commonly eaten in the
Southeastern United States
The Southeastern United States, also referred to as the American Southeast or simply the Southeast, is a geographical region of the United States. It is located broadly on the eastern portion of the southern United States and the southern po ...
sagamite
Sagamité is a Native American stew made from hominy or Indian corn and grease (from animal fat). Additional ingredients may include vegetables, wild rice, brown sugar, beans, smoked fish or animal brains.
Caddo sagamité was thick soup mad ...
.
Maize can also be harvested and consumed in the unripe state, when the kernels are fully grown but still soft. Unripe maize must usually be cooked to become palatable; this may be done by simply boiling or roasting the whole ears and eating the kernels right off the cob.
Sweet corn
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 m ...
, a genetic variety that is high in sugars and low in starch, is usually consumed in the unripe state. Such
corn on the cob
Corn on the cob is a culinary term for a cooked ear of sweet corn ( maize) eaten directly off the cob. The ear is picked while the endosperm is in the "milk stage" so that the kernels are still tender. Ears of corn are steamed, boiled, or ...
is a common dish in the United States, Canada, United Kingdom, Cyprus, some parts of South America, and the Balkans, but virtually unheard of in some European countries. Corn on the cob was hawked on the streets of early 19th-century New York City by poor, barefoot " Hot Corn Girls", who were thus the precursors of hot dog carts, churro wagons, and fruit stands seen on the streets of big cities today.
Within the United States, the usage of maize for human consumption constitutes only around 1/40th of the amount grown in the country. In the United States and Canada, maize is mostly grown to feed
livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to anima ...
, as forage, silage (made by fermentation of chopped green cornstalks), or grain. Maize meal is also a significant ingredient of some commercial animal food products.
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, respon ...
gram
The gram (originally gramme; SI unit symbol g) is a 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 water equal to ...
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 o ...
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 coexis ...
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, ...
(B5) and folate (right table for raw, uncooked kernels,
USDA
The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...
Nutrient Database). In moderate amounts, they also supply
dietary fiber
Dietary fiber (in British English fibre) or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Dietary fibers are diverse in chemical composition, and can be grouped generally by th ...
and the
essential minerals
In the context of nutrition, a mineral is a chemical element required as an essential nutrient by organisms to perform functions necessary for life. However, the four major structural elements in the human body by weight (oxygen, hydrogen, carbon ...
,
magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...
and
phosphorus
Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...
whereas other nutrients are in low amounts (table).
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 aromati ...
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 &minu ...
, which accounts for its lower status as a protein source. However, the proteins of beans and legumes complement those of maize.
fodder
Fodder (), also called provender (), is any agricultural foodstuff used specifically to feed domesticated livestock, such as cattle, rabbits, sheep, horses, chickens and pigs. "Fodder" refers particularly to food given to the animals (including ...
for
livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to anima ...
. It is fed to the livestock in various ways. When it is used as a grain crop, the dried kernels 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. T ...
, or they may be shelled off for storage in a grain bin. The farm that consumes the feed may produce it, purchase it on the market, or some of both. When the grain is used for feed, the rest of the plant (the
corn stover
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, bedding (litter), or soil amendment. When the whole maize plant (grain plus stalks and leaves) is used for fodder, it is usually chopped all at once and ensilaged, as digestibility and palatability are higher in the ensilaged form than in the dried form. Maize silage is one of the most valuable forages for ruminants. Before the advent of widespread ensilaging, it was traditional to gather the corn into shocks after harvesting, where it dried further. With or without a subsequent move to the cover of a barn, it was then stored for weeks to several months until fed to the livestock. Today ensilaging can occur not only in
silo
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 ...
es but also in silage wrappers. However, in the tropics, maize can be harvested year-round and fed as green forage to the animals.
Chemicals
Starch from maize can also be made into
plastics
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
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 ...
"Feed maize" is being used increasingly for heating; specialized corn stoves (similar to wood stoves) are available and use either feed maize or wood pellets to generate heat. Maize cobs are also 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 biom ...
fuel source. Maize is relatively cheap and home-heating furnaces have been developed which use maize kernels as a fuel. They feature a large hopper that feeds the uniformly sized maize kernels (or wood pellets or
cherry
A cherry is the fruit of many plants of the genus '' Prunus'', and is a fleshy drupe (stone fruit).
Commercial cherries are obtained from cultivars of several species, such as the sweet '' Prunus avium'' and the sour '' Prunus cerasus''. The ...
pits) into the fire.
Maize is increasingly used as a feedstock for the production of ethanol fuel. When considering where to construct an ethanol plant, one of the site selection criteria is to ensure there is locally available feedstock. Ethanol is mixed with gasoline to decrease the amount of pollutants emitted when used to fuel motor vehicles. High fuel prices in mid-2007 led to higher demand for ethanol, which in turn led to higher prices paid to farmers for maize. This led to the 2007 harvest being one of the most profitable maize crops in modern history for farmers. Because of the relationship between fuel and maize, prices paid for the crop now tend to track the price of oil.
The price of food is affected to a certain degree by the use of maize for biofuel production. The cost of transportation, production, and marketing are a large portion (80%) of the price of food in the United States. Higher energy costs affect these costs, especially transportation. The increase in
food prices
Food prices refer to the average price level for food across countries, regions and on a global scale. Food prices have an impact on producers and consumers of food.
Price levels depend on the food production process, including food marketing a ...
the consumer has been seeing is mainly due to the higher energy cost. The effect of biofuel production on other food crop prices is indirect. Use of maize for biofuel production increases the demand, and therefore price of maize. This, in turn, results in farm acreage being diverted from other food crops to maize production. This reduces the supply of the other food crops and increases their prices.
Maize is widely used in Germany as a feedstock for biogas plants. Here the maize is harvested, shredded then placed in silage clamps from which it is fed into the biogas plants. This process makes use of the whole plant rather than simply using the kernels as in the production of fuel ethanol.
A
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 near
Güssing
Güssing (; hu, Németújvár, Német-Újvár, hr, Novi Grad) is a town in Burgenland, Austria. It is located at , with a population of 3,578 (2022), and is the administrative center of the Güssing district. For centuries the town occupied an ...
,
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, began in 2005. There is potential that diesel can be created 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.
Increasingly, ethanol is being used at low concentrations (10% or less) as an additive in
gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic ...
(
gasohol
Several common ethanol fuel mixtures are in use around the world. The use of pure hydrous or anhydrous ethanol in internal combustion engines (ICEs) is only possible if the engines are designed or modified for that purpose, and used only in autom ...
) for motor fuels to increase the octane rating, lower pollutants, and reduce petroleum use (what is nowadays also known as "
biofuels
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 ...
" and has been generating an intense debate regarding the human beings' necessity of new sources of energy, on the one hand, and the need to maintain, in regions such as Latin America, the food habits and culture which has been the essence of civilizations such as the one originated in Mesoamerica; the entry, January 2008, of maize among the commercial agreements of
NAFTA
The North American Free Trade Agreement (NAFTA ; es, Tratado de Libre Comercio de América del Norte, TLCAN; french: Accord de libre-échange nord-américain, ALÉNA) was an agreement signed by Canada, Mexico, and the United States that crea ...
has increased this debate, considering the bad labor conditions of workers in the fields, and mainly the fact that NAFTA "opened the doors to the import of maize from the United States, where the farmers who grow it receive multimillion-dollar subsidies and other government supports. ... According to OXFAM UK, after NAFTA went into effect, the price of maize in Mexico fell 70% between 1994 and 2001. The number of farm jobs dropped as well: from 8.1 million in 1993 to 6.8 million in 2002. Many of those who found themselves without work were small-scale maize growers."). However, introduction in the northern latitudes of the US o tropical maize for biofuels and not for human or animal consumption, may potentially alleviate this.
Commodity
Maize is bought and sold by investors and price speculators as a tradable commodity using corn futures contracts. These "futures" are traded on the Chicago Board of Trade (CBOT) under ticker symbol C. They are delivered every year in March, May, July, September, and December.
Ornamental and other uses
Some forms of the plant are occasionally grown for ornamental use in the garden. For this purpose, variegated and colored leaf forms as well as those with colorful ears are used.
Corncobs can be hollowed out and treated to make inexpensive smoking pipes, first manufactured in the United States in 1869.
An unusual use for maize is to create a " corn maze" (or "maize maze") as a tourist attraction. The idea of a maize maze was introduced by the American Maze Company who created a maze in
Pennsylvania
Pennsylvania (; (Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, Ma ...
in 1993. Traditional mazes are most commonly grown using
yew
Yew is a common name given to various species of trees.
It is most prominently given to any of various coniferous trees and shrubs in the genus ''Taxus'':
* European yew or common yew (''Taxus baccata'')
* Pacific yew or western yew (''Taxus br ...
hedges, but these take several years to mature. The rapid growth of a field of maize allows a maze to be laid out using GPS at the start of a growing season and for the maize to grow tall enough to obstruct a visitor's line of sight by the start of the summer. In Canada and the US, these are popular in many farming communities.
Maize kernels can be used in place of sand in a sandboxlike enclosure for children's play.
Stigmas from female maize flowers, popularly called corn silk, are sold as herbal supplements.
Maize is used as a fish bait, called "dough balls". It is particularly popular in Europe for coarse fishing.
Additionally, feed corn is sometimes used by hunters to bait animals such as deer or wild hogs.
United States usage breakdown
The breakdown of usage of the 12.1-billion-
bushel
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 agri ...
(307-million-tonne) 2008 US maize crop was as follows, according to the World Agricultural Supply and Demand Estimates Report by the USDA.
In the US since 2009/2010, maize feedstock use for ethanol production has somewhat exceeded direct use for livestock feed; maize use for fuel ethanol was 5,130 million bushels (130 million tonnes) in the 2013/2014 marketing year.
A fraction of the maize feedstock dry matter used for ethanol production is usefully recovered as DDGS (dried distillers grains with solubles). In the 2010/2011 marketing year, about 29.1 million tonnes of DDGS were fed to US livestock and poultry.Hoffman, L. and A. Baker. 2011. Estimating the substitution of distillers'grains for corn and soybean meal in the U.S. feed complex. United States Department of Agriculture, Economic Research Service. FDS-11-l-01. 62 pp. Because starch utilization in fermentation for ethanol production leaves other grain constituents more concentrated in the residue, the feed value per kg of DDGS, with regard to ruminant-metabolizable energy and protein, exceeds that of the grain. Feed value for monogastric animals, such as swine and poultry, is somewhat lower than for ruminants.
Comparison to other staple foods
The following table shows the nutrient content of maize and major staple foods in a raw harvested form on a dry weight basis to account for their different water contents. Raw forms are not edible and cannot be digested. These must be sprouted, or prepared and cooked for human consumption. In sprouted or cooked form, the relative nutritional and anti-nutritional contents of each of these staples are different from that of raw form of these staples reported in the table below.
Hazards
Pellagra
When maize was first introduced into farming systems other than those used by traditional native-American peoples, it was generally welcomed with enthusiasm for its productivity. However, a widespread problem of malnutrition soon arose wherever maize was introduced as a
staple food
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 (nutrition), diet for a given person or group of people, supplying a large fraction of ...
. This was a mystery, since these types of malnutrition were not normally seen among the indigenous Americans, for whom maize was the principal staple food.
It was eventually discovered that the 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 ...
— water (the process now known as nixtamalization) — made with ashes and lime (
calcium oxide
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term "'' lime''" connotes calcium-containing inorganic ...
) since at least 1200–1500 BC by
Mesoamericans
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. ...
. They did this to liberate the corn hulls, but (unbeknownst to natives or colonists) it coincidentally liberates the B-vitamin niacin, the lack of which was the underlying cause of the condition known as pellagra.
Maize was introduced into the diet of non-indigenous Americans without the necessary cultural knowledge acquired over thousands of years in the Americas. In the late 19th century, pellagra reached epidemic proportions in parts of the southern US, as medical researchers debated two theories for its origin: the deficiency theory (which was eventually shown to be true) said that pellagra was due to a deficiency of some nutrient, and the germ theory said that pellagra was caused by a germ transmitted by stable flies. A third theory, promoted by the eugenicist Charles Davenport, held that people only contracted pellagra if they were susceptible to it due to certain "constitutional, inheritable" traits of the affected individual.Precis by Jan Coe /ref>
Once alkali processing and dietary variety were understood and applied, pellagra disappeared in the developed world. The development of high lysine maize and the promotion of a more balanced diet have also contributed to its demise. Pellagra still exists today in food-poor areas and refugee camps where people survive on donated maize. Also .
Allergy
Maize contains lipid transfer protein, an indigestible protein that survives cooking. This protein has been linked to a rare and understudied
allergy
Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include Allergic rhinitis, hay fever, Food allerg ...
to maize in humans. The allergic reaction can cause skin rash, swelling or itching of mucous membranes, diarrhea, vomiting,
asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, c ...
and, in severe cases,
anaphylaxis
Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the follo ...
. It is unclear how common this allergy is in the general population.
The ''Z. mays'' plant has an OPALS allergy scale rating of 5 out of 10, indicating moderate potential to cause allergic reactions, exacerbated by over-use of the same plant throughout a garden. Corn pollen is heavy, large, and usually airborne in the early morning.
Mycotoxins
Fungicide application does not reduce fungal growth or mycotoxin dramatically, although it can be a part of a successful reduction strategy. Among the most common toxins are those produced by '' Aspergillus'' and '' Fusarium'' spp. The most common toxins are
aflatoxin
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, sweet ...
s, fumonisins, zearalenone, and ochratoxin A. Bt maize discourages insect vectors and by so doing it dramatically reduces concentrations of fumonisins, significantly reduces aflatoxins, but only mildly reduces others.
Art
Maize has been an essential crop in the
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 ...
since the
pre-Columbian era
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, ...
. The Moche culture from Northern Peru made ceramics from earth, water, and fire. This pottery was a sacred substance, formed in significant shapes and used to represent important themes. Maize was represented anthropomorphically as well as naturally.
In the United States, maize ears along with tobacco leaves are carved into the capitals of columns in the
United States Capitol
The United States Capitol, often called The Capitol or the Capitol Building, is the Seat of government, seat of the Legislature, legislative branch of the Federal government of the United States, United States federal government, which is form ...
building. Maize itself is sometimes used for temporary architectural detailing when the intent is to celebrate the fall season, local agricultural productivity and culture. Bundles of dried maize stalks are often displayed along with pumpkins, gourds and straw in autumnal displays outside homes and businesses. A well-known example of architectural use is the Corn Palace in Mitchell, South Dakota, which uses cobs and ears of colored maize to implement a mural design that is recycled annually. Another well-known example is the ''
Field of Corn
''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, where hundreds of concrete ears of corn stand in a grassy field.
A maize stalk with two ripe ears is depicted on the 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 ...
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 soften ...
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 maize dishes
This is a list of maize dishes, in which maize (corn) is used as a primary ingredient. Additionally, some foods and beverages that are prepared with maize are listed.
Ingredients
Corn can be processed into an intermediate form to be cooked furt ...
*
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 ...
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 ot ...
*
* Byerlee, Derek. "The globalization of hybrid maize, 1921–70." ''Journal of Global History'' 15.1 (2020): 101–122.
* Clampitt, Cynthia. ''Maize: How Corn Shaped the U.S. Heartland'' (2015)
*
*