biology of economic agriculture

1. Zea mays
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Maize = Corn

2. Maize Producing Countries
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3. World Corn Production
World of Corn 2006 (NCGA)
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4. Top ten maize producers in 2007
Top ten maize producers in 2007
Country Production (tons)
United States 332,092,180
China 151,970,000
Brazil 51,589,721
Mexico 22,500,000
Argentina 21,755,364
India 16,780,000
France 13,107,000
Indonesia 12,381,561
Canada 10,554,500
Italy 9,891,362
World 784,786,580
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5. Taxonomy of Maize
Kingdom: Plantae (Plants)
Subkingdom: Tracheobionta (Vascular plants)
Superdivision: Spermatophyta (Seed plants)
Division: Magnoliophyta (Flowering plants)
Class: Liliopsida (Monocotyledons)
Subclass: Commelinidae
Order: Cyperales
Family: Poaceae (Grass family)
Genus: Zea L. (corn)
Species: Zea mays L. (corn)
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6. Zea mays General Structure
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Tassel
Ear
Adventious Roots

7. General Structure
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8. Maize Inflorescence
Male Inflorescence (Tassel) Female Inflorescence (Ear)
Style (Silk)
Caryopsis
(Kernel)
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9. Origin
 It may be a direct domestication of a
Mexican annual teosinte, Zea mays
ssp. 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. luxurians
or Z. diploperennis. 9

10. 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

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

12. Types of Corns
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13. 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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14. 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.
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15. 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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16. 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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17. 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.
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18. 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

19. 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

20. 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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21. 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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22. 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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23.  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

24.  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

25.  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

26. 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

27. 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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28. 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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29. 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

30. 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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31. 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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32. 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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33. Hybrid Corn
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34. Hybrid Corn
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35. 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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36. 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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