Maize, also known as corn, is a cereal grain that is the third most important crop worldwide after rice and wheat. It originated in Mexico and Central America and is a member of the grass family. Maize has a life cycle of 120 to 150 days and produces ears containing kernels as its fruit. It is an important food crop for humans and animals as well as a raw material for many industrial products. Plant breeders use techniques like selfing and crossing to produce genetically pure maize seed.

1. Maize
Kumari Shikha
Assistant Professor
DDU Gorakhpur University

2. Maize (Corn) - Zea mays (2n=20)
• Maize plant belongs to the tribe Maydeae of the grass family Poaceae.
• Zea (zela) word was derived from an old Greek name which refer to food
grass.
• It is cultivated globally being the third most important cereal crops
worldwide after rice and wheat.
• Corn has a life cycle of 120 to 150 days.
• Possess protein- Zein
• Maize deficient in lysine and tryptophan
• Opaque-2 gene (QPM)- rich in lysine and tryptophan
• People dependent on only maize as staple crop – suffer from Pellagra (due
to deficiency of niacin)

3. Taxonomy
Kingdom: Plantae
Division: Magnoliophyta (Flowering plants)
Class: Liliopsida (Monocotyledons)
Order: Poales
Family: Poaceae
Genus: Zea
Species: mays

4. Centre of origin
• Mexico and Central America

6. Evolution of maize:
• Probable ancestor of maize: Zea mexicana
• Three general theories regarding the origin of maize:
i. Some authors reviewed that it originated from pod-corn, Zea mays var.
tunicata.
ii. Maize originated from teosinte, Euchlaena mexicana, which is a wild
grass native to Guatemala and Mexico, by direct selection, mutations or
by the hybridization of Euchlaena with a grass which is presently
unknown.
iii. Zea, Euchlaena and Tripsacum all three have been descended from a
common ancestor through divergent evolution but the ancestor may
have lost.

7. Growth stages of corn
Growth stages of corn
1. Vegetative growth stage 2. Reproductive growth stages
Seedling Emergence, Leaf and Tasseling stage Silking, blister, milk, dough and maturity stage

8. Botanical description

9. Habitat
• Tropical and sub-tropical

10. Habit
• Herbaceous annual, tall and C4 plant with determinate growth.
• It is protoandrous crop.

11. Stem
• Stem: Stout, solid with distinct nodes and internodes. It consist of
sheath surrounding the stalk.

12. Roots
• It consist of fibrous root system.
• Brace roots are formed at the bottom of the stalk
and provide support to the plant and scavenge top
levels of soil for moisture and nutrients.
• Seminal roots or nodal roots originate from scutellar
node and sustain seedling development by virtue
water intake.

13. Leaves
• Leaves are broad and a single leaf at
each node.
• Leaves are arranged in two vertical rows
on the opposite sides of an axis
(distichous).
• Long, large, alternate with parallel
venation.

14. Inflorescence
• Unisexual or Monoecious- Male and
female inflorescence located at different
parts of the plant.
• Male inflorescence is terminal staminate
compound raceme called tassel.
• Female inflorescence is auxiliary pistillate
spadix called ear.
• Maize pollen dispersion by wind.

15. Tassel
• Male reproductive part of the corn plant also known as androecium
• Stalk Also known as filament, the part of the stamen the anther develop.
• Anther is the terminal part of a stamen where the pollens are produced.
• Male inflorescence consists of many spikelets.
• The spikelets occur in pairs—the lower one is sessile and the upper one is stalked.
• Each spikelet consist of two floret. They have four glumes. The first and the second glumes
located at the base are sterile and the third one, called flowering glume and the last one, the
two-nerved palea, enclose a flower. Flowers are obviously monoecious. Perianth is
represented by a pair of fleshy scale-like bodies called lodicules.
• Androecium is composed of three free stamens with long prominent linear anthers

16. Ear
• The ear is the female reproductive part of a corn plant.
• Ears develop from "shanks," which are stalk-like structures
that grow from the plant's leaf nodes.
• A corn plant may produce many ears, but the uppermost
ear will grow to be the largest.
• Ear is covered by the leaf like structures called husks
(bracts)
• The ear consists of a cob, eggs that eventually develop into
kernels and silks.

17. Fruit
• Caryopsis (79% starch and 9% protein)

18. Economic importance
• Maize is not only an important food crop for human
consumption, but also a basic element of animal feed
and raw material for manufacturing of many
industrial products.
• It is also used in the production of biofuel, Gluten
starch, ethanol, refined corn oil, sorbitol,
maltodextrins, cake mixes, candies, beer, carbonated
beverages, paper adhesives and cosmetics etc.
Corn starch
Corn Beer
Corn Oil
Bioplastic
Yoghurt
Spark plugs
Rubber tyre

19. Selfing technique
• Maize, being a cross-pollinated crop, various reproductive isolation
methods are used by plant breeders and by seed producer to produce
genetically pure seed.
• Top portion of ear is removed before emergence of silk and bagged with
butter paper bag. When silk arise from bagged ear, tassel of the same plant
is covered with tassel paper in the evening hours. Pollen is collected in the
bag by tapping it gently then dusted over silk of the same plant to ensure
selfing. Plant is tagged with date of selfing.

20. Crossing technique
• Top portion of the ear is removed before emergence of silk and
covered with butter paper bag. When silk arise from bagged ear,
tassel of the different plant from which pollen is to be taken, is
covered with tassel bag in the evening hours. Pollen is collected in the
bag by tapping it gently then dusted over silk of the bagged ear to
ensure cross pollination. Plant is labelled with date of crossing and
parent names.

21. 1. Cut the ear before emergence of silk

22. 2. Cover ear with silk bag

23. 3. Bagging of tassel to collect pollen

24. 4. Collect pollen next morning hours

25. 5. Dust the pollen over silk

26. 7. Bagging and tagging of pollinated ear