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
inflorescence
An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
s (or "tassels") and separate ovuliferous inflorescences called
ears
An ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists o ...
that when fertilized yield
kernels
Kernel may refer to:
Computing
* Kernel (operating system), the central component of most operating systems
* Kernel (image processing), a matrix used for image convolution
* Compute kernel, in GPGPU programming
* Kernel method, in machine learnin ...
or seeds, 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 particu ...
s. The term ''maize'' is preferred in formal, scientific, and international usage as a common name because it refers specifically to this one grain, unlike ''corn'', which has a complex variety of meanings that vary by context and geographic region.
Maize has become a staple food in many parts of the world, with the total production of maize surpassing that of
wheat
Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
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 domesticat ...
. In addition to being consumed directly by humans (often in the form of
masa
''Masa'' (or ''masa de maíz'') (; ) is a maize dough that comes from ground nixtamalized corn. It is used for making corn tortillas, '' gorditas'', ''tamales'', '' pupusas'', and many other Latin American dishes. It is dried and powdered into ...
maize products
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...
flour corn
Flour corn (''Zea mays'' var. ''amylacea'') is a variety of corn with a soft starchy endosperm and a thin pericarp. It is primarily used to make corn flour.
This type, frequently found in Aztec and Inca graves, is widely grown in the drier parts ...
, and sweet corn. Sugar-rich varieties called sweet corn are usually grown for human consumption as kernels, while
field corn Field corn, also known as cow corn, is a North American term for maize (''Zea mays'') grown for livestock fodder (silage), ethanol, cereal, and processed food products. The principal field corn varieties are dent corn, flint corn, flour corn (also ...
varieties are used for animal feed, various corn-based human food uses (including grinding into cornmeal or
masa
''Masa'' (or ''masa de maíz'') (; ) is a maize dough that comes from ground nixtamalized corn. It is used for making corn tortillas, '' gorditas'', ''tamales'', '' pupusas'', and many other Latin American dishes. It is dried and powdered into ...
, 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 ...
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 hydropon ...
throughout the Americas, with 384 million metric tons grown in the United States alone in 2021.
Genetically modified maize
Genetically modified maize ( corn) is a genetically modified crop. Specific maize strains have been genetically engineered to express agriculturally-desirable traits, including resistance to pests and to herbicides. Maize strains with both tra ...
cultigen
A cultigen () or cultivated plant is a plant that has been deliberately altered or selected by humans; it is the result of artificial selection. These plants, for the most part, have commercial value in horticulture, agriculture or forestry. Beca ...
; 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 "By faith and hope"
,
, image_map =
, mapsize = 300 px
, map_caption = Location of Tehuacán within the state of Puebla.
, image_map1 = Puebla en México.svg
, mapsize1 = 300 px
, ma ...
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 Alta ...
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
The Brazilian Agricultural Research Corporation (Embrapa - pt, Empresa Brasileira de Pesquisa Agropecuária) is a state-owned research corporation affiliated with the Brazilian Ministry of Agriculture. Since its inception on April 26, 1973, it ha ...
(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 popul ...
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 ...
; they cooked, ground and processed it through
nixtamalization
Nixtamalization () is a process for the preparation of corn, or other grain, in which the grain is soaked and cooked in an alkaline solution, usually limewater (but sometimes aqueous alkali metal carbonates), washed, and then hulled. The ter ...
. 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 ...
quinoa
Quinoa (''Chenopodium quinoa''; , from Quechua ' or ') is a flowering plant in the amaranth family. It is a herbaceous annual plant grown as a crop primarily for its edible seeds; the seeds are rich in protein, dietary fiber, B vitamins, a ...
pre-Hispanic
In the history of the Americas, the pre-Columbian era spans from the original settlement of North and South America in the Upper Paleolithic period through European colonization, which began with Christopher Columbus's voyage of 1492. Usually, th ...
times; however, potato was the staple food 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
Lácar is a department located in the south of Neuquén Province, Argentina.
Geography
The Department limits with Huiliches Department at North, Collón Cura Department at northeast, Rio Negro Province at southeast, Los Lagos Department at ...
. 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, Ascenc ...
(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 ...
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 archaeologi ...
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 ...
, or potatoes. Maize flour could not be substituted for wheat for communion bread, since in Christian 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 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
Food energy is chemical energy that animals (including humans) derive from their food to sustain their metabolism, including their muscular activity.
Most animals derive most of their energy from aerobic respiration, namely combining the carbohy ...
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 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 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
West is a cardinal direction or compass point.
West or The West may also refer to:
Geography and locations
Global context
* The Western world
* Western culture and Western civilization in general
* The Western Bloc, countries allied with NATO ...
; 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 referring to any cereal crop with its meaning understood to vary geographically to refer to the local staple. 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), 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 ...
later naming it kukuruz, or barbaric.
The word ''maize'' is used by agricultural bodies and research institutes such as the UN's
FAO
The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
, 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 gra ...
) 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
In medicine, a pulse represents the tactile arterial palpation of the cardiac cycle (heartbeat) by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed near the surface of the body, such as at the n ...
.
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
A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves, flowers and fruits, transports water and dissolved substances between the roots and the shoots in the xylem and phloem, stores nutrien ...
of length. The leaves arise from the nodes, alternately on opposite sides on the stalk, and have
entire margin
This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...
s.
The apex of the stem ends in the tassel, an
inflorescence
An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
of male flowers. When the tassel is mature and conditions are suitably warm and dry, anthers on the tassel
dehisce
Dehiscence is the splitting of a mature plant structure along a built-in line of weakness to release its contents. This is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part; structures that op ...
and release pollen. Maize pollen is
anemophilous
Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including grasses, sedges, and rushes. Other common anemophilous plan ...
(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 Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
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
Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggr ...
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 fuse ...
", 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 ...
, 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 angiospe ...
". The cob is close to a multiple fruit in structure, except that the individual fruits (the kernels) never fuse into a single mass. The grains are about the size of
pea
The pea is most commonly the small spherical seed or the seed-pod of the flowering plant species ''Pisum sativum''. Each pod contains several peas, which can be green or yellow. Botanically, pea pods are fruit, since they contain seeds and d ...
s, 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
''Glaucous'' (, ) is used to describe the pale grey or bluish-green appearance of the surfaces of some plants, as well as in the names of birds, such as the glaucous gull (''Larus hyperboreus''), glaucous-winged gull (''Larus glaucescens''), gl ...
,
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, 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
Gluten is a structural protein naturally found in certain cereal grains. Although "gluten" often only refers to wheat proteins, in medical literature it refers to the combination of prolamin and glutelin proteins naturally occurring in all grai ...
of wheat and, therefore, makes baked goods with poor rising capability. A genetic variant that accumulates more sugar and less starch in the ear is consumed as a vegetable and is called sweet corn. Young ears can be consumed raw, with the cob and silk, but as the plant matures (usually during the summer months), the cob becomes tougher and the silk dries to inedibility. By the end of the growing season, the kernels dry out and become difficult to chew without cooking.
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 infrastruct ...
usually rely on dense planting, which produces one ear per stalk. Stands of
silage
Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage ...
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 day
Growing degree days (GDD), also called growing degree units (GDUs), are a heuristic tool in phenology. GDD are a measure of heat accumulation used by horticulturists, gardeners, and farmers to predict plant and animal development rates such as the ...
s > 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 mechani ...
s is genetically prescribed and regulated by the
phytochrome
Phytochromes are a class of photoreceptor in plants, bacteria and fungi used to detect light. They are sensitive to light in the red and far-red region of the visible spectrum and can be classed as either Type I, which are activated by far-re ...
system.
Photoperiodicity
A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., Endogeny (biology), endogeno ...
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 as ...
). DIMBOA is a member of a group of
hydroxamic acid
A hydroxamic acid is a class of organic compounds bearing the functional group RC(O)N(OH)R', with R and R' as organic residues and CO as a carbonyl group. They are amides (RC(O)NHR') wherein the NH center has an OH substitution. They are often us ...
s (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 Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
. DIMBOA is also found in related grasses, particularly wheat. A maize mutant (bx) lacking DIMBOA is highly susceptible to attack by
aphid
Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...
s and
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
. DIMBOA is also responsible for the relative resistance of immature maize to the
European corn borer
The European corn borer (''Ostrinia nubilalis''), also known as the European corn worm or European high-flyer, is a moth of the family Crambidae which includes other grass moths. It is a pest of grain, particularly maize (''Zea mays''). The in ...
(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 anthocyanins and
phlobaphene
Phlobaphenes (or phlobaphens, CAS No.:71663-19-9) are reddish, alcohol-soluble and water-insoluble phenolic substances. They can be extracted from plants, or be the result from treatment of tannin extracts with mineral acids (tanner's red). The nam ...
s. These latter substances are synthesized in the flavonoids synthetic pathway from polymerization of
flavan-4-ol
The flavan-4-ols (3-deoxyflavonoids) are flavone-derived alcohols and a family of flavonoids. Flavan-4-ols are colorless precursor compounds that polymerize to form red phlobaphene pigments. They can be found in the sorghum. Glycosides (abacopteri ...
s by the expression of maize pericarp color1 (p1) gene which encodes an R2R3
myb
MyB (Hangul: 마이비) was a South Korean girl group formed by Maroo Entertainment. The group debuted on August 25, 2015 with ''My Oh My'' and made a comeback on November 13, 2015 with ''Ddoddo'', before the group officially disbanded on December ...
-like
transcriptional activator
A transcriptional activator is a protein (transcription factor) that increases transcription of a gene or set of genes. Activators are considered to have ''positive'' control over gene expression, as they function to promote gene transcription and ...
of the A1 gene encoding for the
dihydroflavonol 4-reductase
In enzymology, a dihydrokaempferol 4-reductase () is an enzyme that catalyzes the chemical reaction
:cis-3,4-leucopelargonidin + NADP+ \rightleftharpoons (+)-dihydrokaempferol + NADPH + H+
Thus, the two substrates of this enzyme are cis-3,4 ...
(reducing
dihydroflavonol
The flavanonols (with two "o"s a.k.a. 3-hydroxyflavanone or 2,3-dihydroflavonol) are a class of flavonoids that use the 3-hydroxy-2,3-dihydro-2-phenylchromen-4-one (IUPAC name) backbone.
Some examples include:
* Taxifolin (or Dihydroquercetin)
* ...
s into flavan-4-ols) while another gene (Suppressor of Pericarp Pigmentation 1 or SPP1) acts as a
suppressor
A silencer, also known as a sound suppressor, suppressor, or sound moderator, is a muzzle device that reduces the acoustic intensity of the muzzle report (sound of a gunshot) and muzzle rise when a gun (firearm or air gun) is discharged, b ...
. 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
A grain is a small, hard, dry fruit (caryopsis) – with or without an attached husk, 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 l ...
. 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 Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
s containing both male and female flowers, or hermaphrodite flowers.
Genetics
Maize is an annual grass in the family
Gramineae
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 and ...
, 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 archaeologi ...
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 p ...
,
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 domesticat ...
, sorghum, 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 wid ...
type of teosinte. The
annual
Annual may refer to:
*Annual publication, periodical publications appearing regularly once per year
** Yearbook
** Literary annual
*Annual plant
*Annual report
*Annual giving
*Annual, Morocco, a settlement in northeastern Morocco
*Annuals (band), ...
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: ''Z. m.'' var. ''everta''
* Dent corn : ''Z. m.'' var. ''indentata''
* Flint corn: ''Z. m.'' var. ''indurata''
* Sweet corn: ''Z. m.'' var. ''saccharata'' and ''Z. m.'' var. ''rugosa''
*
Waxy corn
Waxy may refer to:
* a substance related to wax
* colloquially for a waxworm (particularly used by anglers)
* Waxy (band), an American stoner rock band
* Waxy (horse), a thoroughbred racehorse
* WAXY (AM), a radio station (790 AM) licensed to se ...
: ''Z. m.'' var. ''ceratina''
*
Amylomaize Amylomaize was a term coined in the late 1940s by Robert P. Bear of Bear Hybrids Corn Company in Decatur, Illinois to describe his discovery and commercial breeding of a cornstarch with high (>50%) amylose content, also called high amylose starch. ...
: ''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
Agricultural economics is an applied field of economics concerned with the application of economic theory in optimizing the production and distribution of food and fiber products.
Agricultural economics began as a branch of economics that spe ...
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 and ...
, protein and DNA evidence was added. Now, the categories are forms (little used), races, racial complexes, and recently branches.
Maize is a diploid with 20
chromosome
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
s (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
Heterochromia is a variation in coloration. The term is most often used to describe color differences of the iris, but can also be applied to color variation of hair or skin. Heterochromia is determined by the production, delivery, and concentra ...
domains that stain darkly. Individual knobs are polymorphic among strains of both maize and teosinte.
Barbara McClintock 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. Tra ...
theory of "jumping genes", for which she won the 1983
Nobel Prize in Physiology or Medicine
The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, accord ...
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 Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. Satellite DNA is the main component of functional centromeres, and form the main structural constituent of heterochromatin.
The name "satellite DNA" refers to the ...
; and a few of a family of
retrotransposon
Retrotransposons (also called Class I transposable elements or transposons via RNA intermediates) are a type of genetic component that copy and paste themselves into different genomic locations (transposon) by converting RNA back into DNA through ...
s. The
B chromosome
In addition to the normal karyotype, wild populations of many animal, plant, and fungi species contain B chromosomes (also known as supernumerary, accessory, (conditionally-)dispensable, or lineage-specific chromosomes). By definition, these chro ...
, 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 and ...
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 Univ ...
, is a stock center of maize mutants. The total collection has nearly 80,000 samples. The bulk of the collection consists of several hundred named genes, plus additional gene combinations and other heritable variants. There are about 1000 chromosomal aberrations (e.g., translocations and inversions) and stocks with abnormal chromosome numbers (e.g.,
tetraploid
Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contains ...
s). 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 A Ministry of Energy or Department of Energy is a government department in some countries that typically oversees the production of fuel and electricity; in the United States, however, it manages nuclear weapons development and conducts energy-re ...
(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 g ...
. 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. Tra ...
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
Rolling circle replication (RCR) is a process of unidirectional nucleic acid replication that can rapidly synthesize multiple copies of circular molecules of DNA or RNA, such as plasmids, the genomes of bacteriophages, and the circular RNA geno ...
transposons.
In ''Z. mays'' and various other angiosperms the
MADS-box
The MADS box is a conserved sequence motif. The genes which contain this motif are called the MADS-box gene family. The MADS box encodes the DNA-binding MADS domain. The MADS domain binds to DNA sequences of high similarity to the motif CC /Tsub>6G ...
motif is involved in 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 a ...
sites under selection.Recombination is a significant source of
diversity
Diversity, diversify, or diverse may refer to:
Business
*Diversity (business), the inclusion of people of different identities (ethnicity, gender, age) in the workforce
*Diversity marketing, marketing communication targeting diverse customers
* ...
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 In genetics, the gene density of an organism's genome is the ratio of the number of genes per number of base pairs, usually written in terms of a million base pairs, or ''megabase'' (Mb). The human genome has a gene density of 11-15 genes/Mb, while ...
. 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
polyploid
Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...
y 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
Out-crossing or out-breeding is the technique of crossing between different breeds. This is the practice of introducing distantly related genetic material into a breeding line, thereby increasing genetic diversity.
Outcrossing can be a usefu ...
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
Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and o ...
lines (G. H. Shull, 1909), and the highly successful double cross hybrids using four inbred lines ( D. F. Jones c. 1918, 1922). University supported breeding programs were especially important in developing and introducing modern hybrids. By the 1930s, companies such as
Pioneer
Pioneer commonly refers to a settler who migrates to previously uninhabited or sparsely inhabited land.
In the United States pioneer commonly refers to an American pioneer, a person in American history who migrated west to join in settling and de ...
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 Univ ...
maintain
germplasm
Germplasm are living genetic resources such as seeds or tissues that are maintained for the purpose of animal and plant breeding, preservation, and other research uses. These resources may take the form of seed collections stored in seed banks, t ...
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
An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...
" used as a vegetable in
Asian cuisine
Asian cuisine includes several major regional cuisines: Central Asian, East Asian, North Asian, South Asian, Southeast Asian, and West Asian. A cuisine is a characteristic style of cooking practices and traditions, usually associated with ...
.
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
Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including t ...
(GE) maize was one of the 26 GE crops grown commercially in 2016. The vast majority of this is
Bt maize
Genetically modified maize (corn) is a genetically modified crop. Specific maize strains have been genetically engineered to express agriculturally-desirable traits, including resistance to pests and to herbicides. Maize strains with both trait ...
. 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
Starlink is a satellite internet constellation operated by SpaceX, providing satellite Internet access coverage to 45 countries. It also aims for global mobile phone service after 2023. SpaceX started launching Starlink satellites in 2019. As ...
genetically modified corn, which had been approved only for animal consumption 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 plant disease resistance, for disease and plant defense against herbivory, 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 genome, genomic regions providing sorghum downy mildew resistance, 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 of a Mexican people, Mexican annual teosinte, Zea mays ssp. parviglumis, ''Z. m.'' ssp. ''parviglumis'', native to the
Balsas River
The Balsas River (Spanish Río Balsas, also locally known as the Mezcala River, or Atoyac River) is a major river of south-central Mexico.
The basin flows through the states of Guerrero, México, Morelos, and Puebla. Downstream of Ciudad Alta ...
valley in south-eastern Mexico, with up to 12% of its genetic material obtained from Zea mays ssp. mexicana, ''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 Zea luxurians, ''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 and subspecies in the genus ''Zea'', excluding Zea mays ssp. mays, ''Z. m.'' ssp. ''mays''.)
# It has evolved from a hybridization of ''Z. diploperennis'' by ''Tripsacum dactyloides''.
In the late 1930s, Paul Mangelsdorf suggested that domesticated maize was the result of a hybridization event between an unknown wild maize and a species of ''Tripsacum'', a related genus. This theory about the origin of maize has been refuted by modern genetic testing, which refutes Mangelsdorf's model and the fourth listed above.
The teosinte origin theory was proposed by the Russian botanist Nikolai Ivanovich Vavilov in 1931 and the later American Nobel Prize-winner George Beadle in 1932. 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 of maize is of particular interest to researchers—archaeologists, geneticists, ethnobotany, ethnobotanists, geographers, etc. The process is thought by some to have started 7,500 to 12,000 years ago. Research from the 1950s to 1970s originally focused on the hypothesis that maize domestication occurred in the highlands between the states of Oaxaca and Jalisco, because the oldest archaeological remains of maize known at the time were found there.
Connection with 'parviglumis' subspecies
Genetic studies, published in 2004 by John Doebley, identified Zea mays ssp. parviglumis, ''Zea mays'' ssp. ''parviglumis'', native to the
Balsas River
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 Alta ...
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.
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 Tehuacán, Puebla, Tehuacan, Puebla, 5,450 Before Present, B.P.
Maize pollen dated to 7,300 B.P. from San Andrés (Mesoamerican site), 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 (plant), squash, Andean region potato,
quinoa
Quinoa (''Chenopodium quinoa''; , from Quechua ' or ') is a flowering plant in the amaranth family. It is a herbaceous annual plant grown as a crop primarily for its edible seeds; the seeds are rich in protein, dietary fiber, B vitamins, a ...
, beans, and amaranth – of most pre-Columbian North American, Mesoamerican, South American, and Caribbean cultures. The Mesoamerican civilization, in particular, was deeply interrelated with maize. Its traditions and rituals involved all aspects of maize cultivation – from the planting to the food preparation. Maize formed the Mesoamerican people's identity.
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 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 ...
United States Forest Service, Forest Service suggested that the rise in maize cultivation 500 to 1,000 years ago in what is now the southeastern United States corresponded with a decline of freshwater mussels, which are very sensitive to environmental changes.
Cultivation
Planting
Because it is cold-intolerant, in the Temperate, temperate zones maize must be planted in the spring. Its root system is generally shallow, so the plant is dependent on soil moisture. As a plant that uses C4 carbon fixation, maize is a considerably more water-efficient crop than plants that use C3 carbon fixation such as alfalfa and soybeans. Maize is most sensitive to drought at the time of silk emergence, when the flowers are ready for pollination. In the United States, a good harvest was traditionally predicted if the maize was "knee-high by the Independence Day (United States), Fourth of July", although modern Hybrid (biology), hybrids generally exceed this growth rate. Maize used for
silage
Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage ...
is harvested while the plant is green and the fruit immature. Sweet corn is harvested in the "milk stage", after pollination but before starch has formed, between late summer and early to mid-autumn. Field maize is left in the field until very late in the autumn to thoroughly dry the grain, and may, in fact, sometimes not be harvested until winter or even early spring. The importance of sufficient soil moisture is shown in many parts of Africa, where periodic drought regularly causes maize crop failure and consequent famine. Although it is grown mainly in wet, hot climates, it has been said to thrive in cold, hot, dry or wet conditions, meaning that it is an extremely versatile crop.
Maize was planted by the Native American (Americas), Native Americans in hills, in a complex system known to some as the Three Sisters (agriculture), Three Sisters. 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 legumes; and Squash (fruit), squashes 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 gardens is still often planted manually with a hoe (tool), hoe, whereas maize grown commercially is no longer planted manually but rather is planted with a planter (farm implement), planter. In North America, fields are often planted in a two-crop rotation with a Nitrogen fixation, nitrogen-fixing crop, often alfalfa in cooler climates and soybeans 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 anhydrous ammonia, fertilized. Weeds 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, by grazing, or by some combination of those. Whether the ears were hand-picked and the corn stover, stover was grazed, or the whole plant was cut, gathered, and stook, shocked, people and livestock did all the work. Between the 1890s and the 1970s, the technology of maize harvesting expanded greatly. Today, all such technologies, from entirely manual harvesting to entirely mechanized, are still in use to some degree, appropriate technology, as appropriate to each farm's needs, although the thoroughly mechanized versions predominate, as they offer the lowest unit costs when scaled to large farm operations.
Before World War II, most maize in North America was harvested by hand. This involved a large number of workers and associated social events (husking or shucking communal work, bees). From the 1890s onward, some machinery became available to partially mechanize the processes, such as one- and two-row mechanical pickers (picking the ear, leaving the corn stover, stover) and corn binders, which are reaper-binders designed specifically for maize (for example, ). The latter produce sheaf (agriculture), sheaves that can be stook, shocked. By hand or mechanical picker, the entire ear is harvested, which then requires a separate operation of a maize sheller to remove the kernels from the ear. Whole ears of maize were often stored in corn cribs, and these whole ears are a sufficient form for some livestock feeding use. Today corn cribs with whole ears, and corn binders, are less common because most modern farms harvest the grain from the field with a combine harvester, combine and store it in silo#Bins, bins. The combine with a corn head (with points and snap rolls instead of a reel) does not cut the stalk; it simply pulls the stalk down. The stalk continues downward and is crumpled into a mangled pile on the ground, where it usually is left to become organic matter for the soil. The ear of maize is too large to pass between slots in a plate as the snap rolls pull the stalk away, leaving only the ear and husk to enter the machinery. The combine separates the husk and the cob, keeping only the kernels.
The entire maize plant is also harvested as a
silage
Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage ...
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 drying, grain dryers are used to reduce the moisture content by blowing heated air through the grain. This can require large amounts of energy in the form of combustible gases (propane or natural gas) and electricity to power the blowers.
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 bushels), 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 Midwest United States, Midwestern states such as Indiana, Iowa, and Illinois; 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:
Pests
Insects
* African armyworm (''Spodoptera exempta'')
* Eldana, African sugarcane borer (''Eldana saccharina'')
* Asian corn borer (''Ostrinia furnacalis'')
* Common armyworm (''Pseudaletia unipuncta'')
* Common earwig (''Forficula auricularia'')
* Corn delphacid (''Peregrinus maidis'')
* Corn leaf aphid (''Rhopalosiphum maidis'')
* Corn rootworms (''Diabrotica spp'') including Western corn rootworm (''Diabrotica virgifera virgifera'' LeConte), Northern corn rootworm (''Diabrotica barberi, D. barberi'' or ''Diabrotica longicornis, D. longicornis'') and Southern corn rootworm (''Diabrotica undecimpunctata howardi, D. undecimpunctata howardi'')
* Euxesta stigmatias, Corn silkfly (''Euxesta stigmatias'')
* Dusky sap beetle (''Carpophilus lugubris'')
*
European corn borer
The European corn borer (''Ostrinia nubilalis''), also known as the European corn worm or European high-flyer, is a moth of the family Crambidae which includes other grass moths. It is a pest of grain, particularly maize (''Zea mays''). The in ...
(''Ostrinia nubilalis'') (ECB)
* Fall armyworm (''Spodoptera frugiperda'') Some sweet corn varieties have developed partial resistance to fall army worms by producing a unique 33-kD proteinase that significantly retards fall army worm growth.
* Corn earworm/Cotton bollworm (''Helicoverpa zea'')
* Lesser cornstalk borer (''Elasmopalpus lignosellus'')
* Maize weevil (''Sitophilus zeamais'')
* Northern armyworm, Oriental armyworm or Rice ear-cutting caterpillar (''Mythimna separata'')
* Southwestern corn borer (''Diatraea grandiosella'')
* Stalk Borer, Stalk borer (''Papaipema nebris'')
The susceptibility of maize to the European corn borer and corn rootworms, and the resulting large crop losses which are estimated at a billion dollars worldwide for each pest, led to the development of transgenic plants, transgenics expressing the ''Bacillus thuringiensis'' toxin. "Bt maize" is widely grown in the United States and has been approved for release in Europe.
Diseases
* Rust (fungus), Rust
* Corn smut or common smut (''Ustilago maydis''): a fungal disease, known in Mexico as ''huitlacoche'', which is prized by some as a gourmet delicacy in itself
* Northern corn leaf bligh (Purdue Extension site)(Pioneer site)
* Southern corn leaf blight
* Maize downy mildew (''Peronosclerospora'' spp.)
* Maize dwarf mosaic virus
* Maize streak virus
* Stewart's wilt (''Pantoea stewartii'')
* Goss's wilt (Clavibacter michiganensis subsp. nebraskensis, ''Clavibacter michiganensis'' subsp. ''nebraskensis'')
* Grey leaf spot
* Mal de Río Cuarto virus (MRCV)
* Stalk rot
* Ear rot
* ''Aspergillus flavus''
* ''Aspergillus parasiticus, A. parasiticus''
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 in many regions of the world. Maize is used to produce cornstarch, a common ingredient in home cooking and many industrialized food products. Maize starch can be hydrolysis, hydrolyzed and enzymatically treated to produce syrups, particularly high fructose corn syrup, a sweetener; and also fermented and distilled to produce grain alcohol. Grain alcohol from maize is traditionally the source of Bourbon whiskey. Cornmeal, 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 ...
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 (nutrient), niacin, an important nutrient, it was not bioavailable without the process of
nixtamalization
Nixtamalization () is a process for the preparation of corn, or other grain, in which the grain is soaked and cooked in an alkaline solution, usually limewater (but sometimes aqueous alkali metal carbonates), washed, and then hulled. The ter ...
. The
Maya
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 popul ...
used nixtamal meal to make varieties of porridges and tamales. The process was later used in the cuisine of the American South to prepare corn for grits and hominy.
Maize is a staple of Mexican cuisine. Masa (cornmeal treated with limewater) is the main ingredient for tortillas, atole and many other dishes of Central American food. It is the main ingredient of corn tortilla, tamales, pozole, atole and all the dishes based on them, like tacos, quesadillas, chilaquiles, enchiladas, tostada (tortilla), 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 in many cultures: from the polenta of Italy, the ''angu'' of Brazil, the ''mămăligă'' of Romania, to Mush (cornmeal), cornmeal mush in the US (or hominy grits in the South) or the food called mieliepap in South Africa and sadza, nshima, ugali and other names in other parts of Africa. Introduced into Africa by the Portuguese in the 16th century, maize has become Africa's most important staple food crop. These are commonly eaten in the Southeastern United States, foods handed down from Native Americans in the United States, Native Americans, who called the dish sagamite.
Maize can also be harvested and consumed in the unripe state, when the kernels are fully grown but still soft. Unripe maize must usually be cooked to become palatable; this may be done by simply boiling or roasting the whole ears and eating the kernels right off the cob. Sweet corn, a genetic variety that is high in sugars and low in starch, is usually consumed in the unripe state. Such corn on the cob is a common dish in the United States, Canada, United Kingdom, Cyprus, some parts of South America, and the Balkans, but virtually unheard of in some European countries. 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, as forage,
silage
Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage ...
(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, 3% protein, and 1% fat (table). In a 100-gram serving, maize kernels provide 86 calories and are a good source (10–19% of the Daily Value) of the B vitamins, thiamin, Niacin (nutrient), niacin (but see #Pellagra, Pellagra warning below), pantothenic acid (B5) and folate (right table for raw, uncooked kernels, USDA Nutrient Database). In moderate amounts, they also supply dietary fiber and the essential minerals, magnesium and phosphorus whereas other nutrients are in low amounts (table).
Maize has suboptimal amounts of the essential amino acids tryptophan and lysine, which accounts for its lower status as a protein source. However, the proteins of beans and legumes complement those of maize.
Feed and fodder for livestock
Maize is a major source of both grain animal feed, feed and fodder for livestock. It is fed to the livestock in various ways. When it is used as a grain crop, the dried corn kernel, kernels are used as feed. They are often kept on the cob for storage in a corn crib, or they may be shelled off for storage in a grain bin. The farm that consumes the feed may produce it, purchase it on the market, or some of both. When the grain is used for feed, the rest of the plant (the corn stover) can be used later as fodder, bedding (animals), bedding (litter), or soil conditioner, soil amendment. When the whole maize plant (grain plus stalks and leaves) is used for fodder, it is usually forage harvester, chopped all at once and silage, ensilaged, as digestibility and palatability are higher in the ensilaged form than in the dried form. Maize silage is one of the most valuable forages for ruminants. Before the advent of widespread ensilaging, it was traditional to gather the corn into stook, shocks after harvesting, where it dried further. With or without a subsequent move to the cover of a barn, it was then stored for weeks to several months until fed to the livestock. Today ensilaging can occur not only in siloes 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, fabrics, adhesives, and many other chemical products.
The corn steep liquor, a plentiful watery byproduct of maize wet milling process, is widely used in the biochemistry, biochemical industry and research as a culture medium to grow many kinds of microorganisms.
Chrysanthemin is found in purple corn and is used as a food coloring.
Bio-fuel
"Feed maize" is being used increasingly for heating; specialized pellet stove, corn stoves (similar to wood fuel, wood stoves) are available and use either feed maize or wood pellets to generate heat. Maize cobs are also used as a biomass fuel source. Maize is relatively cheap and home-heating furnaces have been developed which use maize kernels as a fuel. They feature a large hopper that feeds the uniformly sized maize kernels (or wood pellets or cherry pits) into the fire.
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 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 anaerobic digesters, biogas plants. Here the maize is harvested, shredded then placed in
silage
Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage ...
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 power plant in Strem near Güssing, Burgenland, Austria, began in 2005. There is potential that Diesel fuel, diesel can be created from the biogas by the Fischer Tropsch method.
Increasingly, ethanol is being used at low concentrations (10% or less) as an additive in gasoline (gasohol) for motor fuels to increase the octane rating, lower pollutants, and reduce petroleum use (what is nowadays also known as "biofuels" and has been generating an intense debate regarding the human beings' necessity of new sources of energy, on the one hand, and the need to maintain, in regions such as Latin America, the food habits and culture which has been the essence of civilizations such as the one originated in Mesoamerica; the entry, January 2008, of maize among the commercial agreements of North American Free Trade Agreement, NAFTA has increased this debate, considering the bad labor conditions of workers in the fields, and mainly the fact that NAFTA "opened the doors to the import of maize from the United States, where the farmers who grow it receive multimillion-dollar subsidies and other government supports. ... According to OXFAM UK, after NAFTA went into effect, the price of maize in Mexico fell 70% between 1994 and 2001. The number of farm jobs dropped as well: from 8.1 million in 1993 to 6.8 million in 2002. Many of those who found themselves without work were small-scale maize growers."). 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 pipe (tobacco), 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 in 1993. Traditional mazes are most commonly grown using taxus, yew hedge (gardening), hedges, but these take several years to mature. The rapid growth of a field of maize allows a maze to be laid out using Global Positioning System, GPS at the start of a growing season and for the maize to grow tall enough to obstruct a visitor's line of sight by the start of the summer. In Canada and the US, these are popular in many farming communities.
Maize kernels can be used in place of sand in a sandpit, sandboxlike enclosure for children's play.
Stigmas from female maize flowers, popularly called corn silk, are sold as herbalism, herbal supplements.
Maize is used as a Bait (luring substance), 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 (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 matter#Dry matter basis, 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. 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 — water (the process now known as
nixtamalization
Nixtamalization () is a process for the preparation of corn, or other grain, in which the grain is soaked and cooked in an alkaline solution, usually limewater (but sometimes aqueous alkali metal carbonates), washed, and then hulled. The ter ...
) — made with ashes and lime (calcium oxide) since at least 1200–1500 BC by Mesoamericans. They did this to liberate the corn hulls, but (unbeknownst to natives or colonists) it coincidentally liberates the B-vitamin Niacin (nutrient), niacin, the lack of which was the underlying cause of the condition known as pellagra.
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 proteins, lipid transfer protein, an indigestible protein that survives cooking. This protein has been linked to a rare and understudied allergy to maize in humans. The allergic reaction can cause skin rash, swelling or itching of mucous membranes, diarrhea, vomiting, asthma and, in severe cases, anaphylaxis. It is unclear how common this allergy is in the general population.
The ''Z. mays'' plant has an OPALS (Ogren Plant Allergy Scale), OPALS allergy scale rating of 5 out of 10, indicating moderate potential to cause allergic reactions, exacerbated by over-use of the same plant throughout a garden. Corn pollen is heavy, large, and usually airborne in the early morning.
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 aflatoxins, fumonisins, zearalenone, and ochratoxin A.
Bt maize
Genetically modified maize (corn) is a genetically modified crop. Specific maize strains have been genetically engineered to express agriculturally-desirable traits, including resistance to pests and to herbicides. Maize strains with both trait ...
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. The Moche culture, Moche culture from Northern Peru made ceramics from earth, water, and fire. This pottery was a sacred substance, formed in significant shapes and used to represent important themes. Maize was represented anthropomorphically as well as naturally.
In the United States, maize ears along with tobacco leaves are carved into the capitals of columns in the United States Capitol building. Maize itself is sometimes used for temporary architectural detailing when the intent is to celebrate the fall season, local agricultural productivity and culture. Bundles of dried maize stalks are often displayed along with pumpkins, gourds and straw in autumnal displays outside homes and businesses. A well-known example of architectural use is the Corn Palace in Mitchell, South Dakota, which uses cobs and ears of colored maize to implement a mural design that is recycled annually. Another well-known example is the ''Field of Corn'' sculpture in Dublin, Ohio, where hundreds of concrete ears of corn stand in a grassy field.
A maize stalk with two ripe ears is depicted on the Obverse and reverse, reverse of the Croatian 1 Croatian kuna, lipa coin, minted since 1993.Croatian National Bank : [http://www.hnb.hr/novcan/kovanice/e1lipa.htm?tsfsg=dd58a2499ab048a6770b27c3017b7ec2 1 Lipa Coin] . Retrieved on March 31, 2009.
See also
* Blue corn
* Purple corn
* Columbian Exchange
* Corn syrup
* Crop circle
* Detasseling
* List of maize dishes
* List of sweetcorn varieties
* Post-harvest losses (grains)
* Push–pull technology, pest control strategy for maize and sorghum
* Zein
References
Further reading
*
* 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)
*
*
Maize Genetics Cooperation Stock Center *
*
* Corn: "The Outer Limits" ', ca. 1976, Archives of Ontario YouTube Channel
{{Authority control
Maize,
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Agriculture in Mesoamerica
Crops originating from Mexico
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Energy crops
Flora of Guatemala
Flora of Mexico
Fruit vegetables
Grasses of Mexico
Plant models
Pre-Columbian Native American cuisine
Post-Columbian Native American cuisine
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Staple foods
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Plants described in 1753
Symbols of Illinois