Zea mays

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Maize = Corn

Maize Producing Countries

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World Corn Production

3World of Corn 2006 (NCGA)

Top ten maize producers in 2007Top ten maize producers in 2007

Country Production (tons)

United States 332,092,180China 151,970,000Brazil 51,589,721Mexico 22,500,000Argentina 21,755,364India 16,780,000France 13,107,000Indonesia 12,381,561Canada 10,554,500Italy 9,891,362World 784,786,580

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Taxonomy of MaizeKingdom: Plantae (Plants)Subkingdom: Tracheobionta (Vascular plants)

Superdivision: Spermatophyta (Seed plants)Division: Magnoliophyta (Flowering plants)

Class: Liliopsida (Monocotyledons)Subclass: Commelinidae

Order: CyperalesFamily: Poaceae (Grass family)

Genus: Zea L. (corn)Species: Zea mays L. (corn)

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Zea mays General Structure

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Tassel

Ear

Adventious Roots

General Structure

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Male Inflorescence (Tassel) Female Inflorescence (Ear)

Style (Silk)

Caryopsis(Kernel)

Maize Inflorescence

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Origin It may be a direct domestication of a

Mexican annual teosinte, Zea maysssp. parviglumis, native to the Balsas River valley in south-eastern Mexico

It may have been derived from hybridization between a small domesticated maize and a teosinte of section Luxuriantes, either Z. luxuriansor Z. diploperennis. 9

Origin It may have undergone two or more

domestications either of a wild maize or of a teosinte.

It may have 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. 10

11A Tripsacum grass (big) and a teosinte (small)

Types of Corns

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Varieties of corns Dent corn — Zea mays var. indentata Flint corn — Zea mays var. indurata Popcorn — Zea mays var. everta Flour corn — Zea mays var. amylacea Sweet corn — Zea mays var. saccharata and

Zea mays var. rugosa Waxy corn — Zea mays var. ceratina Amylomaize — Zea mays Pod corn — Zea mays var. tunicata Striped maize — Zea mays var. japonica

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Dent Corn (Zea mays indenata)

getting its name from the dent in the crown of the seed is grown more than any other type of corn is used for human and industrial use, and

for livestock feed The starch reaches the summit of the

seed, and the sides are also starchy The denting is caused by the drying and

shrinking of the starch. BACK

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Flint Corn (Zea mays indurata) Flint corn kernels are hard and smooth

and have little soft starch Flint corn is grown in the United States Asia, Central America, Europe, and South America

In temperate zones, flint corn matures earlier, has better germination, and the plant vigour is earlier than in dent.

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BACK

Pop Corn (Zea mays everta) Popcorn is an extreme form of flint It has a very small proportion of soft

starch It is a very minor crop, and is gown

mostly for humans to eat The reason is "pops" so well, is because

of the horny endosperm, which is a tough, stretchy material that can resist the pressure of steam, which is generated in the hot kernel until it has enough force to explode or "pop."

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Flour Corn (Zea mays amylacea)

Flour corn contains a lot of soft starch, and has almost no dent

it is grown in the drier sections of the US a din the Andean region of South America.

It's an older type of corn, and is found in a lot of graves of the Aztecs and Incas

Since the kernel is so soft, the American Indians could make it into flour.

BACK

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Sweet Corn (Zea saccharata/Z. rugosa)

Sweet Corn has an almost clear, horny kernel when it is still young

The kernels become wrinkled when dry The ears can be eaten fresh, or can be

stored in cans The only difference between sweet and

dent corn is that sweet corn has a gene which prevents some sugar from being converted into starch. 18

Waxy Corn

These kernels appear waxy Chemically, it has a different type of

starch than normal corn starch It was developed in China, and some

waxy mutations have occurred in America dent strains

Very little is grown, is used for producing a starch similar to tapioca starch. 19

Pod Corn

Pod corn isn't grown commercially, but it is used a lot in studying the origin of corn

It resembles varieties of the primitive corns

Every kernel we enclosed in a pod and the whole ear is also enclosed in a husk.

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BACK

Biology and morphology Maize has 2n=20 chromosomes (n=10) The combined length of the

chromosomes is 1500 cM Some of the maize chromosomes have

what are known as "chromosomal knobs": highly repetitive heterochromatic domains that stain darkly.

Individual knobs are polymorphic among strains of both maize and teosinte.

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Biology and morphology Barbara McClintock used these knob

markers to prove her transposon theory of "jumping genes

Annual herbaceous cultivated crop. Anemophilous, monoecious plant with

diclinous inflorescences and an upright, cylindrical, leaf-bearing stem ranging in height from 50-80 cm to 5-6 m

Maize features a powerful, well-developed root system.

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The number of internodes and leaves vary greatly depending on growing conditions and plant genotype

Large, ribbon lanceolate or large lanceolate leaves, ciliated at the edge, grow from opposite sides of the plant in an alternating pattern; the leaf sheath is open, with a ciliated lingula

Spikelets are unisexual; male and female ones are bunched in different inflorescences.

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Biology and morphology

Staminate (male) flowers are borne on the tassel

The tassel consists of many pairs of lanceolate spikelets 6-8 mm long situated along the branches of the tassel

Spikelets have one, two, rarely three flowers

Pistillate (female) flowers - the cob (each plant bearing 1-2, rarely 3 cobs) is up to 45 cm long - take shape inside leaf collars.

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Biology and morphology

there are vertical rows of 4-48 spikelets with pistillate (female) flowers.

Each spikelet consists of a pair of flowers (florets), but only the upper one is subject to development.

Ovary is superior, sessile, unilocular with one seed-bud.

Style is very long, filiform with a bilobar stigma on top.

The average number of kernels per cob is 500-1000.

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Biology and morphology

Ecology Maize is a spring, heat-loving crop It is light-demanding and drought-enduring. The growing period usually lasts 90-150

days. Maize is fastidious about soil. maize yields a good harvest in black, gray-

wooded, chestnut and derno-podzolic soils with a deep humic horizon, good water retention and water permeability 26

Ecology The optimal soil pH level is 6.6-7.7, and the

soil weight is 1.1-1.3 g per cm3. it takes about 25 kg N, 9 kg P and 20 kg K

to form 1,000 kg of maize kernels, the plants should be supplied with these

substances during the whole vegetation period, mostly at the stage of ear-formation, florescence, and kernel formation.

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Distribution Maize is one of the oldest plants incapable

of self-seeding and of running wild. Native to Central and South America. First cultivated in what is now Mexico by

the ancient Maya and Aztec (≈ 5,200 B.C.) The most common opinion is that maize

originated through domestication of the wild grass teosinte (Euchlaena mexicana), which is native to Mexico.

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Distribution The area of maize cultivation starts at

58°N latitude and reaches 40°S latitude. Maize is widely cultivated in the USA Brazil Mexico southern and southeastern Europe Southeast Asia South and East Africa Russia 29

Distribution In 2004, there were over 350 maize hybrids

and lines distributed among the regions of the Russian Federation 114 of them are grown for their kernels 136 are grown for general purposes 42 are grown for silage Principal hybrids include Almaz Barbados, Belozerny 1 Galina

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Insect pests Corn earworm (Helicoverpa zea) Fall armyworm (Spodoptera frugiperda) Common armyworm (Pseudaletia unipuncta) Stalk borer (Papaipema nebris) Corn leaf aphid (Rhopalosiphum maidis) European corn borer (Ostrinia nubilalis) Corn silkfly (Euxesta stigmatis) Lesser cornstalk borer (Elasmopalpus lignosellus) Corn delphacid (Peregrinus maidis) Western corn rootworm (Diabrotica virgifera virgifera

LeConte) Southwestern corn borer (Diatraea grandiosella)

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Diseases 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.

Maize dwarf mosaic virus Stewart's Wilt (Pantoea stewartii) Common Rust (Puccinia sorghi) Goss's Wilt (Clavibacter michiganese) Grey Leaf Spot Mal de Río Cuarto Virus (MRCV) Stalk and Kernal Rot

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Hybrid Corn

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Hybrid Corn

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Bt Corn The susceptibility of maize to the

European corn borer, and the resulting large crop losses, led to the development of transgenic expressing the Bacillus thuringiensis toxin

"Bt maize " is widely grown in the United States and has been approved for release in Europe.

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Bt Corn The Bt delta endotoxin was selected

because it is highly effective at controlling Lepidoptera larvae, caterpillars. It is during the larval stage when most of the damage by European corn borer occurs.

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