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From Wikipedia, the free encyclopediaJump to:navigation,searchThis article is about the cereal grain. For other uses, seeMaize (disambiguation)."Corn" redirects here. For other uses, seeCorn (disambiguation).

In British English "corn" means anycereal.

Maize

Illustration depicting both male andfemale flowers of maize

Scientific classification

Kingdom: Plantae

(unranked): Angiosperms

(unranked): Monocots

(unranked): Commelinids

Order: Poales

Family: Poaceae

Subfamily: Panicoideae

Tribe: Andropogoneae

Genus: Zea

Species: Z. mays

Subspecies: Z. mayssubsp.mays

Trinomial name

Zea mayssubsp. maysL.

Maize(/mez/MAYZ;Zea mayssubsp. mays, from Spanish: mazafterTanomahiz), known

in some English-speaking countries as corn, is a largegrainplant domesticated byindigenous

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peoplesinMesoamericainprehistoric times.The leafy stalk produces ears which contain thegrain, which are seeds calledkernels.Maize kernels are used in cooking as astarch.

Contents

1 History 2 Etymology 3 Structure and physiology 4 Genetics 5 Breeding

o 5.1 Genetic modification 6 Origin 7 Production

o 7.1 Methodso 7.2 Quantity

7.2.1 United States 8 Pests

o 8.1 Insectso 8.2 Diseases

9 Useso 9.1 Human foodo 9.2 Alternative medicineo 9.3 Chemicalso 9.4 Bio-fuelo 9.5 Ornamental and other useso 9.6 Foddero 9.7 Commodityo 9.8 U.S. usage breakdown

10 Comparison to other staple foods 11 Hazards

o 11.1 Pellagrao 11.2 Allergy

12 Art 13 See also 14 Notes 15 References 16 Further reading 17 External links

History

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ure_and_physiologyhttp://en.wikipedia.org/wiki/Maize#Etymologyhttp://en.wikipedia.org/wiki/Maize#Historyhttp://en.wikipedia.org/wiki/Starchhttp://en.wikipedia.org/wiki/Corn_kernelshttp://en.wikipedia.org/wiki/Prehistoryhttp://en.wikipedia.org/wiki/Mesoamericahttp://en.wikipedia.org/wiki/Indigenous_peoples

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A maize heap at the harvest site, India

TheOlmecandMayanscultivated it in numerous varieties throughout Mesoamerica, cooked,ground or processed throughnixtamalization.Beginning about 2500 BC, the crop spread throughmuch of theAmericas.[1]The region developed a trade network based on surplus and varieties ofmaize crops. AfterEuropean contact with the Americasin the late 15th and early 16th centuries,explorers and traders carried maize back to Europe and introduced it to other countries. Maize

spread to the rest of the world because of its ability to grow in diverse climates. Sugar-richvarieties calledsweet cornare usually grown for human consumption, whilefield cornvarietiesare used for animal feed and as chemical feedstocks.

Maize is the most widely grown graincropthroughout the Americas,[2]with 332 millionmetrictonsgrown annually in the United States alone. Approximately 40% of the crop130 milliontonsis used for cornethanol.[3]Genetically modified maizemade up 85% of the maizeplanted in the United States in 2009.[4]

Etymology

Many small male flowers make up the male inflorescence, called the tassel.

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The word maizederives from the Spanish form of the indigenousTanoword for the plant,maiz.[5]It is known by other names around the world.

CornoutsideNorth America,Australia,andNew Zealandmeans anycerealcrop, its meaningunderstood to vary geographically to refer to the localstaple.[6][7]In theUnited States,[6]

Canada,

[8]

Australia, and New Zealand,

[citation needed]

cornprimarily means maize; this usagestarted as a shortening of "Indian corn".[6]"Indian corn" primarily means maize (the staple grainofindigenous Americans), but can refer more specifically to multicolored "flint corn"used fordecoration.[9]

In places outside North America, Australia, and New Zealand, cornoften refers to maize inculinary contexts. The narrower meaning is usually indicated by some additional word, as insweet corn,dent corn,corn on the cob,popcorn,corn flakes,baby corn.

InSouthern Africa,maize is commonly called mielie(Afrikaans)or mealie(English).[10]

Maizeis preferred in formal, scientific, and international usage because it refers specifically tothis one grain, unlike corn, which has a complex variety of meanings that vary by context andgeographic region.[7]Maizeis used by agricultural bodies andresearch institutessuch as theFAOandCSIRO.National agricultural and industry associations often include the word maizein theirname even in English-speaking countries where the local, informal word is something other thanmaize; for example, the Maize Association of Australia, the Indian Maize DevelopmentAssociation, the Kenya Maize Consortium and Maize Breeders Network, the National MaizeAssociation of Nigeria, the Zimbabwe Seed Maize Association. However, in commoditiestrading, cornconsistently refers to maize and not other grains.[

citation needed]

Structure and physiology

The maize plant is often 2.5 m (meters) (8 ft) in height, though some natural strains can grow12 m (40 ft).[11]The stem has the appearance of a bamboo cane and is commonly composed of20internodesof 18 cm (7 in) length.[12][13]A leaf grows from each node, which is generally 9 cm(3.5 in) in width and 120 cm (4 ft) in length.

Ears develop above a few of the leaves in the midsection of the plant, between the stem and leafsheath, elongating by[citation needed]~ 3 mm/day, to a length of 18 cm (7 in) (60 cm/24 in being themaximum observed in the subspecies[14]). They are femaleinflorescences,tightly enveloped byseveral layers of ear leaves commonly called husks. Certain varieties of maize have been bred toproduce many additional developed ears. These are the source of the "baby corn"used as a

vegetable inAsian cuisine.

The apex of the stem ends in the tassel, aninflorescenceof male flowers. When the tassel ismature and conditions are suitably warm and dry, anthers on the tasseldehisceand releasepollen. Maize pollen is anemophilous (dispersed by wind), and because of its large settlingvelocity, most pollen falls within a few meters of the tassel.

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Elongatedstigmas,called silks, emerge from the whorl of husk leaves at the end of the ear. Theyare often pale yellow and 7 in (178 mm) in length, like tufts of hair in appearance. At the end ofeach is a carpel, which may develop into a "kernel" if fertilized by a pollen grain. Thepericarpofthe fruit is fused with the seed coat referred to as "caryopsis", typical of thegrasses,and theentire kernel is often referred to as the "seed". The cob is close to amultiple fruitin structure,

except that the individual fruits (the kernels) never fuse into a single mass. The grains are aboutthe size ofpeas,and adhere in regular rows around a white, pithy substance, which forms the ear(maximum size of kernel in subspecies is reputedly 2.5 cm/1 in[15]). An ear commonly holds 600kernels. They are of various colors: blackish,bluish-gray,purple, green, red, white and yellow.When ground intoflour,maize yields more flour with much lessbranthan wheat does. It lacksthe proteinglutenof wheat and, therefore, makes baked goods with poor rising capability. Ageneticvariant that accumulates more sugar and lessstarchin the ear is consumed as a vegetableand is calledsweet corn.Young ears can be consumed raw, with thecoband silk, but as the plantmatures (usually during the summer months), the cob becomes tougher and the silk dries toinedibility. By the end of thegrowing season,the kernels dry out and become difficult to chewwithout cooking them tender first in boiling water.

Female inflorescence, with young silk

Stalks, ears, and silk

Male flowers

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Full-grown maize plants

Mature maize ear on a stalk

Planting density affects multiple aspects of maize. Modern farming techniques indevelopedcountriesusually rely on dense planting, which produces one ear per stalk.[16]Stands ofsilagemaize are yet denser,[17]and achieve a lower percentage of ears and more plant matter.

Maize is afacultative long-night plant[18]and flowers in a certain number ofgrowing degreedays> 10 C (50 F) in the environment to which it is adapted.[19]The magnitude of theinfluence that long nights have on the number of days that must pass before maizeflowersisgenetically prescribed[20]and regulated by thephytochromesystem.[21]Photoperiodicitycan be

eccentric in tropicalcultivarssuch that the long days characteristic of higher latitudes allow theplants to grow so tall that they do not have enough time to produce seed before being killed byfrost. These attributes, however, may prove useful in using tropical maize forbiofuels.[22]

Immature maize shoots accumulate a powerful antibiotic substance, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA). DIMBOA is a member of a group ofhydroxamic acids(alsoknown as benzoxazinoids) that serve as a natural defense against a wide range of pests, includinginsects,pathogenicfungi andbacteria.DIMBOA is also found in related grasses, particularlywheat. A maize mutant (bx) lacking DIMBOA is highly susceptible to attack byaphidsandfungi.DIMBOA is also responsible for the relative resistance of immature maize to theEuropeancorn borer(familyCrambidae). 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-deficientsoils, and prone to be uprooted by severe winds.[23]

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Maize kernels

Maize plant diagram

Ear of maize with irregular rows of seeds

Exotic varieties of maize are collected to addgenetic diversitywhen selectively breedingnew domestic strains

Variegated maize ears

Zea mays "strawberry" -MHNT

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Genetics

Many forms of maize are used for food, sometimes classified as various subspecies related to theamount of starch each has:

Flour cornZea maysvar. amylacea PopcornZea maysvar. everta Dent cornZea maysvar. indentata Flint cornZea maysvar. indurata Sweet cornZea maysvar.saccharataandZea maysvar. rugosa Waxy cornZea maysvar. ceratina AmylomaizeZea mays Pod cornZea maysvar. tunicataLarraaga ex A. St. Hil. Striped maizeZea maysvar.japonica

This system has been replaced (though not entirely displaced) over the last 60 years by

multivariable classifications based on ever more data.Agronomicdata were supplemented bybotanical traits for a robust initial classification, then genetic,cytological,protein and DNAevidence was added. Now, the categories are forms (little used), races, racial complexes, andrecently branches.

Maize is adiploidwith 20chromosomes(n=10). The combined length of the chromosomes is1500cM.Some of the maize chromosomes have what are known as "chromosomal knobs":highly repetitiveheterochromaticdomains that stain darkly. Individual knobs arepolymorphicamong strains of both maize andteosinte.

Barbara McClintockused these knob markers to validate hertransposontheory of "jumping

genes", for which she won the 1983Nobel Prize in Physiology or Medicine.Maize is still animportantmodel organismfor genetics anddevelopmental biologytoday.[24]

The Maize Genetics Cooperation Stock Center, funded by the USDAAgricultural ResearchServiceand located in the Department of Crop Sciences at theUniversity of Illinois at Urbana-Champaign,is a stock center of maize mutants. The total collection has nearly 80,000 samples.The bulk of the collection consists of several hundred named genes, plus additional genecombinations and other heritable variants. There are about 1000 chromosomal aberrations (e.g.,translocations and inversions) and stocks with abnormal chromosome numbers (e.g.,tetraploids).Genetic data describing the maize mutant stocks as well as myriad other data about maizegenetics can be accessed atMaizeGDB,the Maize Genetics and Genomics Database.[25]

In 2005, the U.S.National Science Foundation(NSF), Department of Agriculture (USDA)andtheDepartment of Energy(DOE) formed a consortium to sequence the B73 maizegenome.Theresulting DNA sequence data was deposited immediately intoGenBank,a public repository forgenome-sequence data. Sequences and genome annotations have also been made availablethroughout the project's lifetime at the project's official site.[26]

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gy_or_Medicinehttp://en.wikipedia.org/wiki/Transposonhttp://en.wikipedia.org/wiki/Barbara_McClintockhttp://en.wikipedia.org/wiki/Teosintehttp://en.wikipedia.org/wiki/Polymorphism_%28biology%29http://en.wikipedia.org/wiki/Heterochromatinhttp://en.wikipedia.org/wiki/Centimorganhttp://en.wikipedia.org/wiki/Chromosomehttp://en.wikipedia.org/wiki/Diploidhttp://en.wikipedia.org/wiki/Cell_biologyhttp://en.wikipedia.org/wiki/Agronomicshttp://en.wikipedia.org/wiki/Pod_cornhttp://en.wikipedia.org/wiki/Amylomaizehttp://en.wikipedia.org/wiki/Waxy_cornhttp://en.wikipedia.org/wiki/Sweet_cornhttp://en.wikipedia.org/wiki/Flint_cornhttp://en.wikipedia.org/wiki/Dent_cornhttp://en.wikipedia.org/wiki/Popcorn

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Primary sequencing of the maize genome was completed in 2008.[27]On November 20, 2009, theconsortium published results of its sequencing effort in Science.[28]The genome, 85% of which iscomposed oftransposons,was found to contain 32,540 genes (By comparison, thehumangenomecontains about 2.9 billion bases and 26,000 genes). Much of the maize genome has beenduplicated and reshuffled byhelitrons- group of rolling circle transposons.[29]

Breeding

Maize breeding in prehistory resulted in large plants producing large ears. Modern breedingbegan with individuals who selected highly productive varieties in their fields and then sold seedto other farmers. James L. Reid was one of the earliest and most successful developing Reid'sYellow Dent in the 1860s. These early efforts were based onmass selection.Later breedingefforts included ear to row selection, (C. G. Hopkins ca. 1896), hybrids made from selectedinbred lines (G. H. Shull, 1909), and the highly successful double cross hybrids using 4 inbredlines (D. F. Jones ca. 1918, 1922). University supported breeding programs were especiallyimportant in developing and introducing modern hybrids. (Ref Jugenheimer Hybrid Maize

Breeding and Seed Production pub. 1958) by the 1930s, companies such asPioneerdevoted toproduction of hybrid maize had begun to influence long term development. Internationallyimportant seed banks such asCIMMYTand the U.S. bank at Maize Genetics Cooperation StockCenterUniversity of Illinois at Urbana-Champaignmaintaingermplasmimportant for futurecrop development.

Genetic modification

Main article:Transgenic maize

Genetically modified(GM) maizeis one of the 25GM cropsgrown commercially in 2011.[30]

Grown since 1997 in the United States and Canada, 86% of the US maize crop was geneticallymodified in 2010[31]and 32% of the worldwide maize crop was GM in 2011.[32]As of 2011,Herbicide-tolerant maize varieties are grown in Argentina, Australia, Brazil, Canada, China,Colombia, El Salvador, the EU, Honduras, Japan, Korea, Malaysia, Mexico, New Zealand,Philippines, the Russian Federation, Singapore, South Africa, Taiwan, Thailand, and USA, andinsect-resistant corn is grown in Argentina, Australia, Brazil, Canada, Chile, China, Colombia,Czech Republic, Egypt, the EU, Honduras, Japan, Korea, Malaysia, Mexico, Netherlands, NewZealand, Philippines, Romania, Russian Federation, South Africa, Switzerland, Taiwan, USA,and Uruguay.[33]

In September 2000, up to $50 million worth ofTaco Bell'sshells were recalledfrom its

restaurants as well as supermarkets. The shells containedgenetically modified cornthat was unfitfor human consumption by theFood and Drug Administration.

Origin

See also:Origin of maize and interaction with teosintes

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aize#cite_note-27

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A Tripsacumgrass (big) and a teosinte (small)

Maize is the domesticated variant ofteosinte.[34]The two plants have dissimilar appearance,maize having a single tall stalk with multiple leaves and teosinte being a short, bushy plant. Thedifference between the two is largely controlled by differences in just two genes.[34]

Several theories had been proposed about the specific origin of maize in Mesoamerica:[35][36]

1. It is a directdomesticationof aMexicanannualteosinte,Zea maysssp.parviglumis,native to theBalsas Rivervalley in south-easternMexico,with up to 12% of itsgeneticmaterialobtained fromZea maysssp. mexicanathroughintrogression.

2. It has been derived from hybridization between a small domesticated maize (a slightlychanged form of a wild maize) and a teosinte of sectionLuxuriantes, eitherZ. luxuriansorZ. diploperennis.

3. It has undergone two or more domestications either of a wild maize or of a teosinte. (Theterm "teosinte" describes allspeciesand subspecies in the genusZea, excludingZea maysssp. mays.)

4. It has evolved from a hybridization ofZ. diploperennisbyTripsacum dactyloides.In the late 1930s, Paul Mangelsdorf suggested that domesticated maize was the result of ahybridization event between an unknown wild maize and a species ofTripsacum,a relatedgenus. This theory about the origin of maize has been refuted by moderngenetic testing,whichrefutes Mangelsdorf's model and the fourth listed above.[35]:40

Guila Naquitz Cave,site of the oldest known remains of maize

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The teosinte origin theory was proposed by the Russian botanistNikolai Ivanovich Vavilovin1931 and the later AmericanNobel Prize-winnerGeorge Beadlein 1932.[35]:10It is supportedexperimentally and by recent studies of the plants' genomes. Teosinte and maize are able tocross-breed and produce fertile offspring. A number of questions remain concerning the species,among them:

1. how the immense diversity of the species of sect.Zeaoriginated,2. how the tiny archaeological specimens of 35002700 BC could have been selected from

a teosinte, and3. 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. 1100BC.

Thedomesticationof maize is of particular interest to researchersarchaeologists,geneticists,ethnobotanists,geographers, etc. The process is thought by some to have started 7,500 to 12,000years ago. Research from the 1950s to 1970s originally focused on the hypothesis that maize

domestication occurred in the highlands between the states ofOaxacaandJalisco,because theoldest archaeological remains of maize known at the time were found there. Genetic studies ledbyJohn DoebleyidentifiedZea maysssp.parviglumis, native to the Balsas River valley inMexico's southwestern highlands, and also known as Balsas teosinte, as being thecrop wildrelativeteosinte genetically most similar to modern maize.[37]However, archaeobotanical studiespublished in 2009 now point to the lowlands of the Balsas River valley, where stone millingtools with maize residue have been found in a 8,700-years old layer of deposits.[38][39][40]Aprimitive corn was being grown in southern Mexico, Central America, and northern SouthAmerica 7,000 years ago. Archaeological remains of early maize ears, found atGuila NaquitzCavein theOaxaca Valley,date back roughly 6,250 years; the oldest ears from caves nearTehuacan,Puebla, date ca. 3,450 BC.[41]Little change occurred in ear form until ca. 1100 BCwhen great changes appeared in ears from Mexican caves: maize diversity rapidly increased andarchaeological teosinte was first deposited.

Field of maize inLiechtenstein

Corn field panorama inAliaga, Nueva Ecija,Philippines.

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Perhaps as early as 2500 BC, maize began to spread widely and rapidly. It was first cultivated inwhat is now the United States, at several sites in New Mexico and Arizona, about 2100 BC.[42]As it was introduced to new cultures, new uses were developed and new varieties selected tobetter serve in those preparations. Maize was the staple food, or a major staple (along withsquash,Andean regionpotato,quinoa,beans,andamaranth), of mostpre-ColumbianNorth

American, Mesoamerican, South American, and Caribbean cultures. The Mesoamericancivilization was strengthened upon the field crop of maize, through harvesting it, its religious andspiritual importance and how it impacted their diet. Maize formed the Mesoamerican people'sidentity. During the first millennium AD, maize cultivation spread from Mexico into the U.S.Southwest and during the following millennium into the U.S. Northeast and southeasternCanada, transforming the landscape as Native Americans cleared large forest and grassland areasfor the new crop.[citation needed]

Centeotl,the Aztec deity of maize

It is unknown what precipitated its domestication, because the edible portion of the wild varietyis too small and hard to obtain to be eaten directly, as each kernel is enclosed in a very hardbivalve shell. However, George Beadle demonstrated that the kernels of teosinte are readily"popped" for human consumption, like modern popcorn. Some have argued it would have takentoo many generations ofselective breedingto produce large, compressed ears for efficientcultivation. However, studies of the hybrids readily made by intercrossing teosinte and modernmaize suggest this objection is not well founded.

In 2005, research by theUSDAForest Servicesuggested that the rise in maize cultivation 500 to1,000 years ago in what is now the southeastern United States corresponded with a decline offreshwatermussels,which are very sensitive to environmental changes.[43]

Production

Methods

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Seedlings three weeks after sowing

Young stalks

Because it is cold-intolerant, in thetemperate zonesmaize must be planted in the spring. Itsrootsystemis generally shallow, so the plant is dependent on soil moisture. As a C4 plant (a plantthat usesC4 carbon fixation), maize is a considerably more water-efficient crop than C3 plants(plants that useC3 carbon fixation)like the small grains,alfalfaandsoybeans.Maize is mostsensitive to drought at the time of silk emergence, when the flowers are ready for pollination. Inthe United States, a good harvest was traditionally predicted if the maize were "knee-high by theFourth of July", although modernhybridsgenerally exceed this growth rate. Maize used forsilageis 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 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 importanceof sufficient soil moisture is shown in many parts ofAfrica,where periodicdroughtregularlycauses maize crop failure and consequentfamine.Although it is grown mainly in wet, hotclimates, it has been said to thrive in cold, hot, dry or wet conditions, meaning that it is anextremely versatile crop.[44]

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Mature plants showing ears

Maize was planted by theNative Americansin hills, in a complex system known to some as the

Three Sisters.Maize provided support forbeans,and the beans provided nitrogen derived fromnitrogen-fixingrhizobiabacteria which live on the roots of beans and otherlegumes;andsquashesprovided ground cover to stop weeds and inhibit evaporation by providing shade overthe soil.[45]This method was replaced by single species hill planting where each hill 60120 cm(2.03.9 ft) apart was planted with three or four seeds, a method still used by home gardeners. Alater technique was "checked maize", where hills were placed 40 inches (1.0 metre) apart in eachdirection, allowing cultivators to run through the field in two directions. In more arid lands, thiswas altered and seeds were planted in the bottom of 1012 cm (3.94.7 in) deep furrows tocollect water. Modern technique plants maize in rows which allows for cultivation while theplant is young, although the hill technique is still used in the maize fields of some NativeAmerican reservations.

In North America, fields are often planted in a two-crop rotationwith anitrogen-fixingcrop,oftenalfalfain cooler climates andsoybeansin regions with longer summers. Sometimes a thirdcrop,winter wheat,is added to the rotation.

Many of the maize varieties grown in the United States and Canada are hybrids. Often thevarieties have beengenetically modifiedto tolerateglyphosateor to provide protection againstnatural pests. Glyphosate is an herbicide which kills all plants except those with genetictolerance. This genetic tolerance is very rarely found in nature.

In midwestern United States, low-till orno-till farmingtechniques are usually used. In low-till,fields are covered once, maybe twice, with a tillage implement either ahead of crop planting orafter the previous harvest. The fields are planted andfertilized.Weeds are controlled through theuse ofherbicides,and no cultivation tillage is done during the growing season. This techniquereduces moisture evaporation from the soil, and thus provides more moisture for the crop. Thetechnologies mentioned in the previous paragraph enable low-till and no-till farming. Weedscompete with the crop for moisture and nutrients, making them undesirable.

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Mature field maize ears

BeforeWorld War II,most maize in North America was harvested by hand. This involves a largenumbers of workers and associated social events (husking or shuckingbees). Some one- andtwo-row mechanical pickers were in use, but the maizecombinewas not adopted until after theWar. By hand or mechanical picker, the entire ear is harvested, which then requires a separateoperation 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.Few modern farms store maize in this manner. Most harvest the grain from the field and store itin bins. The combine with a maize head (with points and snap rolls instead of a reel) does not cutthe stalk; it simply pulls the stalk down. The stalk continues downward and is crumpled into amangled pile on the ground. The ear of maize is too large to pass between slots in a plate as thesnap rolls pull the stalk away, leaving only the ear and husk to enter the machinery. The combineseparates out the husk and the cob, keeping only the kernels.

Quantity

Worldwide maize production

Harvesting maize during the record 2009 season inJones County, Iowa

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Maize is widely cultivated throughout the world, and a greater weight of maize is produced eachyear than any other grain.[citation needed]The United States produces 40% of the world's harvest;other top producing countries include China, Brazil,Mexico,Indonesia,India, France andArgentina.Worldwide production was 817 milliontonnesin 2009more thanrice(678 milliontonnes)orwheat(682 milliontonnes).[2]In 2009, over 159 millionhectares(390 million acres)

of maize were planted worldwide, with a yield of over 5 tonnes/hectare (80 bu/acre). Productioncan be significantly higher in certain regions of the world; 2009 forecasts for production in Iowawere 11614 kg/ha (185 bu/acre).[46][Note 1]There is conflicting evidence to support the hypothesisthat maize yield potential has increased over the past few decades. This suggests that changes inyield 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 perindividual plant.[47]

Top ten maize producers in 2012

Country Production (tonnes) Note

United States 273,832,130China 208,258,000

Brazil 71,296,478

Argentina 25,700,000

Mexico 22,069,254

India 21,060,000

Ukraine 20,961,300

Indonesia 19,377,030

France 15,614,100

South Africa 12,500,000

World 690,668,292 [A]

No symbol = official figure, A = Aggregate (may include official, semiofficial or estimates).[2]

United States

http://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Wikipedia:Citation_neededhttp://en.wikipedia.org/wiki/Mexicohttp://en.wikipedia.org/wiki/Mexicohttp://en.wikipedia.org/wiki/Mexicohttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Indonesiahttp://en.wikipedia.org/wiki/Argentinahttp://en.wikipedia.org/wiki/Argentinahttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Tonnehttp://en.wikipedia.org/wiki/Ricehttp://en.