floral biology cotton

1. Floral Biology Of Cotton
SUBMITTED TO,
Dr P.K Rai
Department of Genetics and
Plant Breeding
SUBMITTED BY
ASHISH SHEERA
ID:-16MSCGPB043

2. SCIENTIFIC CLASSIFICATION
Kingdom: Plantae
Order: Malvales
Family: Malvaceae
Subfamily: Malvoideae
Tribe: Gossypieae
Genus: Gossypium

3. There are four commercially grown species of cotton, all domesticated in antiquity:
 Gossypium hirsutum – upland cotton, native to Central America, Mexico, the Caribbean and
southern Florida (90%of world production)
 Gossypium barbadense – known as extra-long staple cotton, native to tropical South
America (8% of world production)
 Gossypium arboreum– tree cotton, native to India and Pakistan (less than 2%)
 Gossypium herbaceum– Levant cotton, native to southern Africa and the Arabian Peninsula
(less than 2%)
The two New World cotton species account for the vast majority of modern cotton production, but
the two Old World species were widely used before the 1900s. While cotton fibers occur naturally
in colors of white, brown, pink and green, fears of contaminating the genetics of white cotton
have led many cotton-growing locations to ban the growing of colored cotton varieties, which
remain a specialty product.

4. CHARACTERISTICS
Habitat
Terrestrial
Leaf type
the leaves are simple (A simple leaf has a single blade)
Leaf arrangement
alternate: there is one leaf per node along the stem
Pollination
Often cross pollinated
Chromosome no. – 2n=52
Floral Formula: K(5), C5 , A(∝) , G (5)

5. Flower symmetry
there are two or more ways to evenly divide the flower (the flower is
radially symmetrical)
Number of sepals, petals or tepals
there are five petals, sepals, or tepals in the flower
Fusion of sepals and petals
the petals or the sepals are fused into a cup or tube
Stamen number
13 or more
Fruit type (general)
the fruit is dry and splits open when ripe
Fruit length
30–50 mm

6. COTTON FLOWER
 The petals of the cotton flower are a creamy white
to yellow when the flower first opens.
 They are narrow at the base and broad at the tip.
 The petals darken, usually to a dark pink at the end
of the first day.
 Below is a cross section through a petal.
 The flower has three bracts, usually closed about the
square.
 It also has a calyx, which surrounds the developin bud.
 Both the bracts and the calyx serve to protect the flower.
 In the center of the flower is a five lobed pistil,
surrounded by many stamens.
 Each of the stamens has a two lobed anther that
releases pollen.
 Each pollen grain is viable for about 12 hours after
release.

7.  The flower has a superior ovary, consisting of two or more locules, or seed
chambers. Depending upon the species of cotton, each seed chamber can have
8-12 ovules, 5-9 of which usually mature.
 A flower bud, or "square" is produced at every node on the fruiting branches
of the cotton plant. The first square can be seen 35 to 45 days after the plant
begins to grow. The mature flower needs 25 days to fully develop, the buds
that are lowest on the plant develop first.
 The petals of the flower appear to be a light yellow or white when open. After
one day, the petals turn dark and the flower closes. The flower is usually self
pollinated. Pollination usually occurs within that first day, and the ovules are
fertilized about 30 hours after pollination.

8. • The developing flower consists of concentric whorls, the outer one being the bracts.
Inside the bracts is a whorl of sepals (collectively, called the calyx, which are green
and completely enclose the inner developing whorls . The next whorl consists of the
petals (collectively, called the corolla). The next whorl is composed of stamens, the
structures responsible for producing pollen. The white mass in the center of this bud
is most likely immature stamens. The gynoecium (not visible here), or female
reproductive structure, develops within the whorl of stamens.
• As the square develops, the calyx is pushed open, and petals can be seen.
• After 35 to 45 days, the flower opens for a period of one day. The flower either self
pollinated, or sometimes (although rarely) is cross pollinated by insects. After the
ovules are fertilized, the bolls require 40-70 more days to fully mature. The length of
time to maturity depends upon the species of cotton.

9. FLORAL CHARACTERS:
Pedicellate, complete, cyclic, bracteolate in the form of epicalyx, hermaphrodite,
actinomorphic, hypogynous, regular and pentamerous.
PEDICELLATE-A flower with a stalk is called pedunculate or pedicellate
SEXUALITY:
Bisexual- Bisexual or perfect flowers have both male (androecium) and female
(gynoecium) reproductive structures, including stamens and an ovary.
SYMMETRY:
Actinomorphic- . Actinomorphic flowers are also called radially symmetrical or regular
flowers. Flowers that are radially symmetrical so that they are able to be bisected into
similar halves in more than one vertical plane, forming mirror images.
a single flower arising from the axil of the leaf.

10. INFLORESCENCE:
Cyme Or Solitary- in cyme oldest flower terminates the main axis. Solitary means
EPICALYX:
a series of small sepal-like bracts forming an outer calyx beneath the true calyx
Number- 5-7
Colour – Green
An additional whorl below calyx
CALYX:
Number- 5
Fusion- Gamosepalous- having the sepals united.
Aestivation- Valvate
Aestivation or estivation refers to the positional arrangement of the parts of a flower
within a flower bud before it has opened.

11. Valvate aestivation-
margins of adjacent petals or sepals touch each other without overlapping.
Shape –bell shaped
Colour- Green
COROLLA:
Number- 5
Fusion- Polypetalous-having a corolla composed of distinct, separable petals
Aestivation- Twisted
ANDROECIUM:
1.Stamen
Number.-Indefinite
2.Cohesion- Monoadelphous. i.e forming a staminal tube around the style.
united into one bundle or set by their filaments.
3.Adhesion -Epipetalous i.e. filaments adnate to the basal part of the petal.
4. Anthers
Reniform, i.e. kidney shaped
5.Free and monothecous (Monothecous means one chambered)

12. GYNOECIUM:
1.Carpel
Number of carpels-5, (Pentacarpellary)
1.Fusion – Syncarpous- having the carpels united.
Ovary- Superior(A superior ovary is an ovary attached to the receptacle above
the attachment of other floral parts), pentalocular with 1 or 2 ovules in each
locale
Style- Long, united below, free above, passes through staminal tube
Stigma-Five in number
Placentation- Axile ( The ovary is sectioned by radial spokes with placentas
in separate locules)

13. Floral diagram

18. FACTORS AFFECTING GROWTH

20. Thank you