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78-418: The LibertyLink gene is available in a variety of crops including corn , cotton , canola , sugarbeet and soybean . It is not available in rice . In 2006, the U.S. Department of Agriculture announced that Bayer CropScience's LibertyLink genetically modified rice had contaminated the U.S. rice supply. Shortly after the public learned of the contamination, the E.U. banned imports of U.S. long-grain rice and

156-473: A supplement of an individual amino acid (methionine, lysine, threonine, or tryptophan) can be added to the feed. Protein content in foods is often measured in protein per serving rather than protein per calorie. For instance, the USDA lists 6 grams of protein per large whole egg (a 50-gram serving) rather than 84 mg of protein per calorie (71 calories total). For comparison, there are 2.8 grams of protein in

234-490: A body. A positive balance occurs when more nitrogen is consumed than is excreted, which indicates that some of the nitrogen is being used by the body to build proteins. A negative nitrogen balance occurs when more nitrogen is excreted than is consumed, which indicates that there is insufficient intake for the body to maintain its health. Graduate students at the University of Illinois were fed an artificial diet so that there

312-814: A conventional breeding program to provide optimized strains. The program began in the 1980s. Hybrid seeds are distributed in Africa by its Drought Tolerant Maize for Africa project. Tropical landraces remain an important and underused source of resistance alleles – both those for disease and for herbivores . Such alleles can then be introgressed into productive varieties. Rare alleles for this purpose were discovered by Dao and Sood, both in 2014. In 2018, Zerka Rashid of CIMMYT used its association mapping panel, developed for tropical drought tolerance traits. to find new genomic regions providing sorghum downy mildew resistance , and to further characterize known differentially methylated regions . Genetically modified maize

390-403: 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

468-439: A day to have a healthy protein profile, and almost 6 kg to get enough calories. It is recommended that adult humans obtain between 10–35% of their 2000 calories a day as protein. Scientists had known since the early 20th century that rats could not survive on a diet whose only protein source was zein , which comes from maize (corn), but recovered if they were fed casein from cow's milk. This led William Cumming Rose to

546-408: A diet containing no protein and the nitrogen losses recorded. During the first week or more there is a rapid loss of labile proteins. Once the nitrogen losses stabilize, this baseline is determined to be the minimum required for maintenance. Then the test subjects were fed a measured amount of the food being tested. The difference between the nitrogen in that food and the nitrogen losses above baseline

624-408: A large cob. Yellow maizes derive their color from carotenoids ; red maizes are colored by anthocyanins and phlobaphenes ; and orange and green varieties may contain combinations of these pigments. Maize has short-day photoperiodism , meaning that it requires nights of a certain length to flower. Flowering further requires enough warm days above 10 °C (50 °F). The control of flowering

702-499: A measure of protection against a wide range of pests. Because of its shallow roots, maize is susceptible to droughts, intolerant of nutrient-deficient soils, and prone to being uprooted by severe winds. Maize is diploid with 20 chromosomes . 83% of allelic variation within the genome derives from its teosinte ancestors, primarily due to the freedom of Zea species to outcross . Barbara McClintock used maize to validate her transposon theory of "jumping genes", for which she won

780-638: A place but a condition, a savage rather than a civilized grain". International groups such as the Centre for Agriculture and Bioscience International consider maize the preferred common name. The word maize is used by the UN's Food and Agriculture Organization , and in the names of the International Maize and Wheat Improvement Center of Mexico, the Indian Institute of Maize Research,

858-601: A plant that uses C 4 carbon fixation , maize is a considerably more water-efficient crop than plants that use C 3 carbon fixation such as alfalfa and soybeans . Maize is most sensitive to drought at the time of silk emergence, when the flowers are ready for pollination. In the United States, a good harvest was traditionally predicted if the maize was "knee-high by the Fourth of July ", although modern hybrids generally exceed this growth rate. Maize used for silage

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936-588: A serving of raw broccoli (100 grams) or 82 mg of protein per calorie (34 calories total), or the Daily Value of 47.67g of protein after eating 1,690g of raw broccoli a day at 574 cal. An egg contains 12.5g of protein per 100g, but 4 mg more protein per calorie, or the protein DV after 381g of egg, which is 545 cal. The ratio of essential amino acids (the quality of protein) is not taken into account, one would actually need to eat more than 3 kg of broccoli

1014-431: Is 10% to 20% higher than adult levels and those for infants can be as much as 150% higher in the first year of life. Cysteine (or sulfur-containing amino acids), tyrosine (or aromatic amino acids), and arginine are always required by infants and growing children. Methionine and cysteine are grouped together because one of them can be synthesized from the other using the enzyme methionine S -methyltransferase and

1092-612: Is a major pest of maize in Asia. Essential amino acid An essential amino acid , or indispensable amino acid , is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life forms, the nine amino acids humans cannot synthesize are valine , isoleucine , leucine , methionine , phenylalanine , tryptophan , threonine , histidine , and lysine . Six other amino acids are considered conditionally essential in

1170-426: Is a problem in Asia. Some fungal diseases of maize produce potentially dangerous mycotoxins such as aflatoxin . In the United States, major diseases include tar spot , bacterial leaf streak , gray leaf spot , northern corn leaf blight, and Goss's wilt ; in 2022, the most damaging disease was tar spot, which caused losses of 116.8 million bushels . Maize sustains a billion dollars' worth of losses annually in

1248-674: Is a tall stout grass that produces cereal grain . It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte . Native Americans planted it alongside beans and squashes in the Three Sisters polyculture . The leafy stalk of the plant gives rise to male inflorescences or tassels which produce pollen , and female inflorescences called ears . The ears yield grain, known as kernels or seeds. In modern commercial varieties, these are usually yellow or white; other varieties can be of many colors. Maize relies on humans for its propagation. Since

1326-408: Is composed of transposons , contains 32,540 genes. Much of it has been duplicated and reshuffled by helitrons , a group of transposable elements within maize's DNA. 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

1404-537: Is cultivated throughout the world; a greater weight of maize is produced each year than any other grain. In 2020, world production was 1.1 billion tonnes. It is afflicted by many pests and diseases ; two major insect pests, European corn borer and corn rootworms , have each caused annual losses of a billion dollars in the US. Modern plant breeding has greatly increased output and qualities such as nutrition, drought tolerance, and tolerance of pests and diseases. Much maize

1482-414: 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

1560-533: Is now genetically modified . As a food, maize is used to make a wide variety of dishes including Mexican tortillas and tamales , Italian polenta , and American hominy grits . Maize protein is low in some essential amino acids , and the niacin it contains only becomes available if freed by alkali treatment . In Mesoamerica, maize is deified as a maize god and depicted in sculptures. Maize requires human intervention for it to propagate. The kernels of its naturally-propagating teosinte ancestor fall off

1638-468: Is set genetically; the physiological mechanism involves the phytochrome system. Tropical cultivars can be problematic if grown in higher latitudes, as the longer days can make the plants grow tall instead of setting seed before winter comes. On the other hand, growing tall rapidly could be convenient for producing biofuel. Immature maize shoots accumulate a powerful antibiotic substance, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one ( DIMBOA ), which provides

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1716-498: 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 can thrive in cold, hot, dry or wet conditions, meaning that it is an extremely versatile crop. Maize was planted by the Native Americans in small hills of soil, in the polyculture system called the Three Sisters . Maize provided support for beans ;

1794-448: Is somewhat unclear, as some amino acids can be produced from others. The sulfur -containing amino acids, methionine and homocysteine , can be converted into each other but neither can be synthesized de novo in humans. Likewise, cysteine can be made from homocysteine but cannot be synthesized on its own. So, for convenience, sulfur-containing amino acids are sometimes considered a single pool of nutritionally equivalent amino acids as are

1872-411: Is synthesized by the urea cycle to meet the needs of an adult but perhaps not those of a growing child. Amino acids that must be obtained from the diet are called essential amino acids . Eukaryotes can synthesize some of the amino acids from other substrates . Consequently, only a subset of the amino acids used in protein synthesis are essential nutrients . Nonessential amino acids are produced in

1950-405: Is synthesized from NH 4 and glutamate, and asparagine is synthesized similarly. Proline and arginine are both derived from glutamate. Serine , formed from 3-phosphoglycerate , which comes from glycolysis , is the precursor of glycine and cysteine . Tyrosine is synthesized by the hydroxylation of phenylalanine , which is an essential amino acid. Estimating the daily requirement for

2028-557: Is the domesticated variant of the four species of teosintes , which are its crop wild relatives . The teosinte origin theory was proposed by the Russian botanist Nikolai Ivanovich Vavilov in 1931, and the American Nobel Prize -winner George Beadle in 1932. The two plants have dissimilar appearance, maize having a single tall stalk with multiple leaves and teosinte being a short, bushy plant. The difference between

2106-405: Is the leaf most closely associated with a particular developing ear. This leaf and those above it contribute over three quarters of the carbohydrate ( starch ) that fills the grain. The grains are usually yellow or white in modern varieties; other varieties have orange, red, brown, blue , purple , or black grains. They are arranged in 8 to 32 rows around the cob; there can be up to 1200 grains on

2184-612: The Balsas River valley in Mexico's southwestern highlands, as the crop wild relative genetically most similar to modern maize. The middle part of the short Balsas River valley is the likely location of early domestication. Stone milling tools with maize residue have been found in an 8,700 year old layer of deposits in a cave not far from Iguala, Guerrero . Doebley and colleagues showed in 2002 that maize had been domesticated only once, about 9,000 years ago, and then spread throughout

2262-705: The Columbian exchange , it has become a staple food in many parts of the world, with the total production of maize surpassing that of wheat and rice . Much maize is used for animal feed , whether as grain or as the whole plant, which can either be baled or made into the more palatable silage . Sugar-rich varieties called sweet corn are grown for human consumption, while field corn varieties are used for animal feed, for uses such as cornmeal or masa , corn starch , corn syrup , pressing into corn oil , alcoholic beverages like bourbon whiskey , and as chemical feedstocks including ethanol and other biofuels . Maize

2340-426: The aromatic amino acid pair, phenylalanine and tyrosine . Likewise arginine , ornithine , and citrulline , which are interconvertible by the urea cycle , are considered a single group. If one of the essential amino acids is not available in the required quantities, protein synthesis will be inhibited, irrespective of the availability of the other amino acids. Protein deficiency has been shown to affect all of

2418-550: The "quality" or "value" of various kinds of protein. Measures include the biological value , net protein utilization , protein efficiency ratio , protein digestibility corrected amino acid score and the complete proteins concept. These concepts are important in the livestock industry , because the relative lack of one or more of the essential amino acids in animal feeds would have a limiting effect on growth and thus on feed conversion ratio . Thus, various feedstuffs may be fed in combination to increase net protein utilization, or

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2496-607: The 1983 Nobel Prize in Physiology or Medicine . Maize remains an important model organism for genetics and developmental biology . The MADS-box motif is involved in the development of maize flowers. The Maize Genetics and Genomics Database is funded by the US Department of Agriculture to support maize research. The International Maize and Wheat Improvement Center maintains a large collection of maize accessions tested and cataloged for insect resistance. In 2005,

2574-502: The 21st amino acid). Pyrrolysine (considered the 22nd amino acid), which is proteinogenic only in certain microorganisms, is not used by and therefore non-essential for most organisms, including humans. The limiting amino acid is the essential amino acid which is furthest from meeting nutritional requirements. This concept is important when determining the selection, number, and amount of foods to consume because even when total protein and all other essential amino acids are satisfied if

2652-662: The Americas. Maize pollen dated to 7,300 years ago from San Andres, Tabasco has been found on the Caribbean coast. A primitive corn was being grown in southern Mexico, Central America, and northern South America 7,000 years ago. Archaeological remains of early maize ears, found at Guila Naquitz Cave in the Oaxaca Valley , are roughly 6,250 years old; the oldest ears from caves near Tehuacan , Puebla, are 5,450 years old. Around 4,500 years ago, maize began to spread to

2730-479: The B-vitamin niacin , the lack of which caused pellagra . 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 contributed to its demise. Pellagra still exists in food-poor areas and refugee camps where people survive on donated maize. The name maize derives from

2808-709: The Maize Association of Australia, the National Maize Association of Nigeria, the National Maize Association of Ghana, the Maize Trust of South Africa, and the Zimbabwe Seed Maize Association. Maize is a tall annual grass with a single stem, ranging in height from 1.2 m (4 ft) to 4 m (13 ft). The long narrow leaves arise from the nodes or joints, alternately on opposite sides on

2886-586: The Spanish form maíz of the Taíno mahis . The Swedish botanist Carl Linnaeus used the common name maize as the species epithet in Zea mays . The name maize is preferred in formal, scientific, and international usage as a common name because it refers specifically to this one grain, unlike corn , which has a complex variety of meanings that vary by context and geographic region. Most countries primarily use

2964-562: The US National Science Foundation , Department of Agriculture, and the Department of Energy formed a consortium to sequence the maize genome . The resulting DNA sequence data was deposited immediately into GenBank , a public repository for genome-sequence data. Sequencing of the maize genome was completed in 2008. In 2009, the consortium published results of its sequencing effort. The genome, 85% of which

3042-534: The US from each of two major insect pests , namely the European corn borer or ECB ( Ostrinia nubilalis ) and corn rootworms ( Diabrotica spp ) western corn rootworm , northern corn rootworm , and southern corn rootworm . Another serious pest is the fall armyworm ( Spodoptera frugiperda ). The maize weevil ( Sitophilus zeamais ) is a serious pest of stored grain. The Northern armyworm, Oriental armyworm or Rice ear-cutting caterpillar ( Mythimna separata )

3120-459: The actual amino acid content of foods. The USDA used this technique in their own labs to determine the content of 7793 foods across 28 categories. The USDA published the final database in 2018 to the public. The limiting amino acid depends on the human requirements and there are currently two sets of human requirements from authoritative sources: one published by WHO and the other published by USDA . Various attempts have been made to express

3198-427: The amino acids arginine , cysteine , glutamine , glycine , proline and tyrosine are considered conditionally essential , which means that specific populations who do not synthesize it in adequate amounts, such as newborn infants and people with diseased livers who are unable to synthesize cysteine, must obtain one or more of these conditionally essential amino acids from their diet. For example, enough arginine

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3276-418: The beans provided nitrogen derived from nitrogen-fixing rhizobia bacteria which live on the roots of beans and other legumes ; and squashes provided ground cover to stop weeds and inhibit evaporation by providing shade over the soil. Sweet corn, harvested earlier than maize grown for grain, grows to maturity in a period of from 60 to 100 days according to variety. An extended sweet corn harvest, picked at

3354-613: The body of Christ. Maize spread to the rest of the world because of its ability to grow in diverse climates. It was cultivated in Spain just a few decades after Columbus's voyages and then spread to Italy, West Africa and elsewhere. By the 17th century, it was a common peasant food in Southern Europe. By the 18th century, it was the chief food of the southern French and Italian peasantry, especially as polenta in Italy. When maize

3432-653: The body's organs and many of its systems, for example affecting brain development in infants and young children; inhibiting upkeep of the immune system, increasing risk of infection; affecting gut mucosal function and permeability, thereby reducing absorption and increasing vulnerability to systemic disease ; and impacting kidney function. The physical signs of protein deficiency include edema , failure to thrive in infants and children, poor musculature, dull skin, and thin and fragile hair. Biochemical changes reflecting protein deficiency include low serum albumin and low serum transferrin . The amino acids that are essential in

3510-466: The body. The pathways for the synthesis of nonessential amino acids come from basic metabolic pathways. Glutamate dehydrogenase catalyzes the reductive amination of α-ketoglutarate to glutamate . A transamination reaction takes place in the synthesis of most amino acids. At this step, the chirality of the amino acid is established. Alanine and aspartate are synthesized by the transamination of pyruvate and oxaloacetate , respectively. Glutamine

3588-420: The catalyst methionine synthase . Phenylalanine and tyrosine are grouped together because tyrosine can be synthesized from phenylalanine using the enzyme phenylalanine hydroxylase . Historically, amino acid requirements were determined by calculating the balance between dietary nitrogen intake and nitrogen excreted in the liquid and solid wastes, because proteins represent the largest nitrogen content in

3666-577: The cob on their own, while those of domesticated maize do not. All maize arose from a single domestication in southern Mexico about 9,000 years ago. The oldest surviving maize types are those of the Mexican highlands. Maize spread from this region to the lowlands and over the Americas along two major paths. The centre of domestication was most likely the Balsas River valley of south-central Mexico. Maize reached highland Ecuador at least 8000 years ago. It reached lower Central America by 7600 years ago, and

3744-585: The discovery of the essential amino acid threonine . Through manipulation of rodent diets, Rose was able to show that ten amino acids are essential for rats: lysine , tryptophan , histidine , phenylalanine , leucine , isoleucine , methionine , valine , and arginine , in addition to threonine. Rose's later work showed that eight amino acids are essential for adult human beings, with histidine also being essential for infants. Longer-term studies established histidine as also essential for adult humans. The distinction between essential and non-essential amino acids

3822-425: The earliest and most successful, developing Reid's Yellow Dent in the 1860s. These early efforts were based on mass selection (a row of plants is grown from seeds of one parent), and the choosing of plants after pollination (which means that only the female parents are known). Later breeding efforts included ear to row selection (C. G. Hopkins c. 1896), hybrids made from selected inbred lines (G. H. Shull, 1909), and

3900-413: The entire ear is harvested, which requires a separate operation of a maize sheller to remove the kernels from the ear. Whole ears of maize were often stored in corn cribs , sufficient for some livestock feeding uses. Today corn cribs with whole ears, and corn binders, are less common because most modern farms harvest the grain from the field with a combine harvester and store it in bins . The combine with

3978-774: The expansion of the Inca Empire , maize was traded and transported as far south as 40° S in Melinquina, Lácar Department , Argentina, probably brought across the Andes from Chile. After the arrival of Europeans in 1492, Spanish settlers consumed maize, and explorers and traders carried it back to Europe . Spanish settlers much preferred wheat bread to maize. Maize flour could not be substituted for wheat for communion bread, since in Christian belief at that time only wheat could undergo transubstantiation and be transformed into

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4056-642: The futures price plunged. In April 2010, a Lonoke County , Arkansas jury awarded a dozen farmers $ 48 million. The case was appealed to the Arkansas Supreme Court , which affirmed the judgement. On 1 July 2011, Bayer CropScience agreed to a global settlement for up to $ 750 million. This agriculture article is a stub . You can help Misplaced Pages by expanding it . Maize Maize / m eɪ z / ( Zea mays ), also known as corn in North American English ,

4134-532: The highly successful double cross hybrids using four inbred lines ( D. F. Jones c. 1918, 1922). University-supported breeding programs were especially important in developing and introducing modern hybrids. Since the 1940s, the best strains of maize have been first-generation hybrids made from inbred strains that have been optimized for specific traits, such as yield, nutrition, drought, pest and disease tolerance. Both conventional cross-breeding and genetic engineering have succeeded in increasing output and reducing

4212-550: The history of the word corn in North America that "[t]o say the word corn is to plunge into the tragi-farcical mistranslations of language and history". Similar to the British usage, 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; Fussell comments that "they meant not

4290-486: The human diet were established in a series of experiments led by William Cumming Rose . The experiments involved elemental diets to healthy male graduate students. These diets consisted of corn starch , sucrose , butterfat without protein, corn oil , inorganic salts, the known vitamins , a large brown "candy" made of liver extract flavored with peppermint oil (to supply any unknown vitamins), and mixtures of highly purified individual amino acids. The main outcome measure

4368-518: The human diet, meaning their synthesis can be limited under special pathophysiological conditions, such as prematurity in the infant or individuals in severe catabolic distress. These six are arginine , cysteine , glycine , glutamine , proline , and tyrosine . Six amino acids are non-essential ( dispensable ) in humans, meaning they can be synthesized in sufficient quantities in the body. These six are alanine , aspartic acid , asparagine , glutamic acid , serine , and selenocysteine (considered

4446-406: The indispensable amino acids has proven to be difficult; these numbers have undergone considerable revision over the last 20 years. The following table lists the recommended daily amounts currently in use for essential amino acids in adult humans (unless specified otherwise), together with their standard one-letter abbreviations. The recommended daily intakes for children aged three years and older

4524-464: The limiting amino acid is not satisfied then the meal is considered to be nutritionally limited by that amino acid. (*) Pyrrolysine , sometimes considered the "22nd amino acid", is not used by the human body. Of the twenty amino acids common to all life forms (not counting selenocysteine ), humans cannot synthesize nine: histidine , isoleucine , leucine , lysine , methionine , phenylalanine , threonine , tryptophan and valine . Additionally,

4602-419: The machinery. The combine separates the husk and the cob, keeping only the kernels. Drying is vital to prevent or at least reduce damage by mould fungi, which contaminate the grain with mycotoxins . Aspergillus and Fusarium spp. are the most common mycotoxin sources, and accordingly important in agriculture. If the moisture content of the harvested grain is too high, grain dryers are used to reduce

4680-413: The milk stage, can be arranged either by planting a selection of varieties which ripen earlier and later, or by planting different areas at fortnightly intervals. Maize harvested as a grain crop can be kept in the field a relatively long time, even months, after the crop is ready to harvest; it can be harvested and stored in the husk leaves if kept dry. Before World War II , most maize in North America

4758-427: 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. 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 tonnes , led by the United States with 31.0% of

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4836-501: The need for cropland, pesticides, water and fertilizer. There is conflicting evidence to support the hypothesis that maize yield potential has increased over the past few decades. This suggests that changes in yield potential are associated with leaf angle, lodging resistance, tolerance of high plant density, disease/pest tolerance, and other agronomic traits rather than increase of yield potential per individual plant. Certain varieties of maize have been bred to produce many ears; these are

4914-400: The new crop. The rise in maize cultivation 500 to 1,000 years ago in what is now the southeastern United States corresponded with a decline of freshwater mussels , which are very sensitive to environmental changes. Because it is cold-intolerant, in the temperate zones maize must be planted in the spring. Its root system is generally shallow, so the plant is dependent on soil moisture. As

4992-465: The north. In the United States, maize was first cultivated at several sites in New Mexico and Arizona about 4,100 years ago. During the first millennium AD, maize cultivation spread more widely in the areas north. In particular, the large-scale adoption of maize agriculture and consumption in eastern North America took place about A.D. 900. Native Americans cleared large forest and grassland areas for

5070-760: The presence of Starlink genetically modified corn, which had been approved only for animal consumption. The maize genus Zea is relatively closely related to sorghum , both being in the PACMAD clade of Old World grasses, and much more distantly to rice and wheat , which are in the other major group of grasses, the BOP clade . It is closely related to Tripsacum , gamagrass. various grasses e.g. fescue , ryegrass Hordeum (barley) Triticum (wheat) Oryza (rice) Pennisetum (fountaingrasses) Sorghum (sorghum) Tripsacum (gamagrass) Zea mays (maize) other Zea species ( teosintes ) Maize

5148-491: The source of the " baby corn " used as a vegetable in Asian cuisine . A fast-flowering variety named mini-maize was developed to aid scientific research, as multiple generations can be obtained in a single year. One strain called olotón has evolved a symbiotic relationship with nitrogen-fixing microbes, which provides the plant with 29%–82% of its nitrogen. The International Maize and Wheat Improvement Center (CIMMYT) operates

5226-415: The stalk. Maize is monoecious , with separate male and female flowers on the same plant. At the top of the stem is the tassel, an inflorescence of male flowers; their anthers release pollen, which is dispersed by wind . Like other pollen, it is an allergen , but most of it falls within a few meters of the tassel and the risk is largely restricted to farm workers. The female inflorescence, some way down

5304-425: The stem from the tassel, is first seen as a silk, a bundle of soft tubular hairs , one for the carpel in each female flower, which develops into a kernel (often called a seed. Botanically, as in all grasses, it is a fruit, fused with the seed coat to form a caryopsis ) when it is pollinated. A whole female inflorescence develops into an ear or corncob , enveloped by multiple leafy layers or husks. The ear leaf

5382-608: The term maize , and the name corn is used mainly in the United States and a handful of other English-speaking countries. In countries that primarily use the term maize , the word corn may denote any cereal crop, varying geographically with the local staple , such as wheat in England and oats in Scotland or Ireland. The usage of corn for maize started as a shortening of " Indian corn " in 18th-century North America. The historian of food Betty Fussell writes in an article on

5460-472: The total (table). China produced 22.4% of the global total. Many pests can affect maize growth and development, including invertebrates, weeds, and pathogens. Maize is susceptible to a large number of fungal, bacterial, and viral plant diseases . Those of economic importance include diseases of the leaf, smuts such as corn smut , ear rots and stalk rots. Northern corn leaf blight damages maize throughout its range, whereas banded leaf and sheath blight

5538-500: The two is largely controlled by differences in just two genes, called grassy tillers-1 ( gt1 , A0A317YEZ1 ) and teosinte branched-1 ( tb1 , Q93WI2 ). 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 has been refuted by modern genetic testing . In 2004, John Doebley identified Balsas teosinte, Zea mays subsp. parviglumis , native to

5616-589: The valleys of the Colombian Andes between 7000 and 6000 years ago. The earliest maize plants grew a single, small ear per plant. The Olmec and Maya cultivated maize in numerous varieties throughout Mesoamerica ; they cooked, ground and processed it through nixtamalization . By 3000 years ago, maize was central to Olmec culture, including their calendar, language, and myths. The Mapuche people of south-central Chile cultivated maize along with quinoa and potatoes in pre-Hispanic times. Before

5694-537: Was nitrogen balance . Rose noted that the symptoms of nervousness, exhaustion, and dizziness were encountered to a greater or lesser extent whenever human subjects were deprived of an essential amino acid. Essential amino acid deficiency should be distinguished from protein-energy malnutrition , which can manifest as marasmus or kwashiorkor . Kwashiorkor was once attributed to pure protein deficiency in individuals who were consuming enough calories ("sugar baby syndrome"). However, this theory has been challenged by

5772-444: Was a slightly positive nitrogen balance. Then one amino acid was omitted and the nitrogen balance recorded. If a positive balance continued, then that amino acid was deemed not essential. If a negative balance occurred, then that amino acid was slowly restored until a slightly positive nitrogen balance stabilized and the minimum amount recorded. A similar method was used to determine the protein content of foods. Test subjects were fed

5850-458: Was harvested by hand. This involved a large number of workers and associated social events (husking or shucking bees ). From the 1890s onward, some machinery became available to partially mechanize the processes, such as one- and two-row mechanical pickers (picking the ear, leaving the stover ) and corn binders, which are reaper-binders designed specifically for maize. The latter produce sheaves that can be shocked . By hand or mechanical picker,

5928-425: Was introduced into Western farming systems, it was welcomed for its productivity. However, a widespread problem of malnutrition soon arose wherever it had become a staple food . Indigenous Americans had learned to soak maize in alkali -water — made with ashes and lime — since at least 1200–1500 BC, creating the process of nixtamalization. They did this to liberate the corn hulls, but coincidentally it also liberated

6006-466: Was one of the 26 genetically engineered food crops grown commercially in 2016. The vast majority of this is Bt maize . Genetically modified maize has been grown since 1997 in the United States and Canada; by 2016, 92% of the US maize crop was genetically modified. As of 2011, herbicide-tolerant maize and insect-resistant maize varieties were each grown in over 20 countries. In September 2000, up to $ 50 million worth of food products were recalled due to

6084-402: Was the amount the body retained to rebuild proteins. The amount of nitrogen retained divided by the total nitrogen intake is called net protein utilization . The amount of nitrogen retained divided by the (nitrogen intake minus nitrogen loss above baseline) is called biological value and is usually given as a percentage. Modern techniques make use of ion exchange chromatography to determine

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