Cotton, the king of fibers, usually referred as white gold is soft, fluffy staple fiber that grows in a ball, or protective capsule, around the seed of cotton plants of the genus Gossypium.
The plant is shrub native to tropical and subtropical regions around the world, including the Americas, Africa ,and India.
2. INTRODUCTION:
Cotton, the king of fibers, usually referred as white gold
is soft, fluffy staple fiber that grows in a ball, or
protective capsule, around the seed of cotton plants of
the genus Gossypium.
The plant is shrub native to tropical and subtropical
regions around the world, including the Americas,
Africa ,and India.
The greatest diversity of wild cotton species is found in
Mexico, followed by Australia and Africa.
Cotton was independently domesticated in old and new
world
3. Current estimates for world production are about 25 million
tons annually, accounting for 2.5% of the world’s arable
land.
China is the world’s largest producer of the cotton, but
most of this is used domestically and India rank first in
area (1, 10, 00,000 ha).
The United State has been the largest exporter for many
years .some important cotton growing country are India ,
USA, China ,Brazil , Egypt ,Pakistan, Greece ,etc.
In Nepal it is mostly cultivated in western parts of the
country like in Banke, Bardiya, Kailali, Dang, and
kanchanpur.
.In 2003/04 its total production is 12.5 in 15.5 ha ,2009 59
tons in 100ha and in 2010 area and the production of seed
cotton is 121ha and 109 tons (a/c to FAO).
4. Long cotton fiber are spur into thread for textile,
toweling, Paper, Banknotes, surgical sutures, rope,
and Sheets.
Short cotton fibers or linter, provide cellulose used
for dynamites,
sausageskin,lino,cellophane,rayon,photographic
film, nail polish, solid fuel rockets, chewing gums
etc.
crushed cotton seed yields a useful vegetable oil
and the meal from crushed seeds is used for a
cattle feed ,fish bait and organic fertilizer.
5. SPECIES OF COTTON
The genus Gossypium which belong to the family malvaceae and
the tribe Gossypieae, it is the leading fiber crop in the world.
Although the genus has approximately 50 species, including 45
diploids and five allotetraploids
Only four of them are cultivated for their spinable fiber, including
two diploid(2n = 29 = 26): G. arboreum .L (A2A2) and G.
herbaceum L. (A1A1), and two tetraploid (2n = 49 = 52): G.
hirsutum L. (AD1AD1) and G. barbadense L. (AD2AD2)
. The remaining 46 species are distributed throughout the tropics
and subtropics of the world in wild form.
The wild species of Gossypium are important source of useful traits
such as special and superior fiber properties.
6. cytoplasmic male sterility, resistance to biotic and abiotic stress
etc. which can be introgressed into the cultivated germplam in
breeding programmes
.It has become a necessity to develop basic germplam materials
enriched with rare useful genes from wild species through
introgression. Among 46 wild species few wild species are listed
below;
G.africanum
G.amomalum
G.triphyllum
G.capitis viridis
G.sturtianum
G.nandedewarense
G.aridum etc
7. According to the classification of Hutchinson
(1947) the following four cultivated species
contain almost all the varieties of the cotton.
Gossypium herbaceum (n=13)
Gossypium arboreum(n=13)
Gossypium hirsutum (n=26)
Gossypium barbadense(n=26)
G. arboreum and G. herbaceum are
desi cotton whereas G .hirsutum and G.
barbadense are American cotton.
8. Gossypium herbaceum
Gossypium herbaceum, called
Levant cotton, height of 1.5 to 2m.
It is a species of cotton native to
the semi-arid region of sub-
Saharan Africa and Arabia where it
still grows in the wild as a perennial
shrub.
It was first cultivated in western
Sudan from there it spread to India,
before being introduce to Egypt
Its blooming period is late
spring/early summer.
Genome : A1
Ploidy level : 2n=26
9. Morphological features ;
Annual hard stems and branches round, faintly
striated, bent slightly at the joints, sparsely hairy.
Leaves leathery, prominently reticulate, deeply
cordate, less than half cut into 5-7 broad ovate
rotund, suddenly acute or apiculate lobes, below
distinctly pilose, especially along the veins.
Bracteoles large, green coloured, broadly ovate
rotund obtuse, only very slightly united at the
bottom, but profoundly cordate, gashed across the
top into 7-9 fairly long teeth.
Flowers not very large, yellow with purple claws
and rotating to right; calyx large, loose, undulate,
and with large glands.
10. Capsule small, round, pitted with 3-4 valves, seeds
large, angled beaked, coated with grey fuzz and harsh
grayish-white wool.
Some varieties: G 67, K-7, kalyan, Sanjay etc.
Characters of breeding value: Disease, insects and
drought resistance.
Key character for identification;Bushy annual.
Bracteoles flaring widely from the flower bud, usually
broader than long, upper margin usually serrated into 6-
8 teeth.
Capsule small, round with 3-4 locules.
Races of G. herbaceum: Persicum, Kuljianum,
Acerifolium and Wightianum.
11. Gossypium arboreum
Gossypium arboreum ,commonly
called as tree cotton is a species of
cotton native to India ,Pakistan and
other regions of the world .
There is the evidence of its cultivation
as long ago as the Harappa civilization
of the Indus valley for the production of
cotton textile.
The shrub was included in Linnaeus’
species planetarium published in 1753.
Genome: A2,
Ploidy level : 2n=26
Distribution : Indo-Burma, China
and Arab
12. Morphological features :
A perennial, usually 6 to 10 feet in height, having long
trailing thin branches, stems and more especially the
young branches, petioles, peduncles and bracteoles of
a deep glossy purple color
Apeculiarity sometimes even possessed by the young
leaves, especially on the under surface.
Leaves of a thick and leathery consistence, gland
dotted, sub-glabrous or having short, abortively stillate
hairs on the blade, especially more under surface, and a
few younger spreading hairs on the petiole and young
shoots.
Blade of the leaf mostly five to seven lobed.
Flowers yellow with purplish red petal spot. The flower
are set on short pedicel(i.e. flower stalk).
13. The corolla is pale yellow in color some time with purple center
and occasionally entirely purple.
The staminal tubes bear the anther and are 1.5 to 2cm in length.
The fruit is a three to four celled capsule .it is ovoid and oblong in
shape and glabrous(i.e. hairless)
The seed within are globular and are covered in long white
cotton.
Some varieties: Shyamali, Western-1, D46-2-1,231-R etc.
Characters of breeding value: Disease, insects and drought
resistance.
Key character for identification: Bracteoles closely investing
the flower bud, entire or with 3-4 coarse teeth near the apex,
longer than broad. Capsule round to tapering with 3-4 loculi.
Races of Arboreum : Soudanense, Sinense, Burmanicum,
Cernuum, Bengalense and Indicum
14. Gossypium hirsutum
Gossypium hirsutum, known as upland cotton or
Mexican cotton is the most widely planted species of the
cotton ,constituting worldwide some 90% of all
production for this species;
it is native to Central America and possibly Mexico.
G.hirustum include number of varieties or cross bred
cultivar with varying fiber lengths and tolerance to a
number of growing condition.
Highly adoptable cultivar like Laxmi and Gujarat 67 also
belongs to this species.
The longer length varieties are called 'long staple
upland" and the shorter length varieties are referred to
as“ short staple upland“ the long staple varieties are
mostly cultivated in commercial production.
Genome : (AD)1
Ploidy level : 2n=52
Distribution : America
15. Morphological features ;
Annual shrub of 1 to 1.5 m tall, stem
tip green to pigmented, glabrous to
densely hairy.
Leaf broad to very narrow, nectaries
present, pedicel large variable,
bracteole size large but variable,
serrations few to several.
Corolla yellow, petal spot usually
absent.
Bolls is rounded, 3to 5locular with 5
to 7 seeds per locules.
Seed bear copious lint and a thick
Fuzz.
Anther color greenish to yellow
16. Stigma generally none protruding. Boll round, oval or
elongated large.
Locules 3-5, generally smooth, tip blunt, lint white, cream,
brown, green etc.
Characters of breeding value : Fiber yield, length,
strength, fineness and
Elongation, resistance to Verticillium wilts absent.
Some Varieties: 320F, H14, Indore-1, laxmi, Krishna,
Narbada.
Key character for identification : Flower yellow and petal
spot usually a
Races of G.hirustum : Latifolium, Punctatum, Morilli,
Richmondii, Palmeri, Marie Galente, and Yucatenense
17. Gossypium barbadense
Gossypium barbadense, also known
as extra-long staple cotton as it is generally
has a staple of at least 13/8" or longer.
It is tropical frost sensitive perennial plant
that produce yellow flower and has black
seed.
it grows as a small bushy tree and yield
cotton with unusually long, silky fibers. To
grow, it requires full sun and high humidity
and rainfall.
This plant contain the chemical gossypol,
which reduces its susceptibility to insect and
fungal damage .
The leaves of G. barbadense are used to
treat hypertension and delayed irregular
menstruation.
it contributes about 8% of total cotton
production.
Genome : (AD)2
Ploidy level : 2n=52
Distribution: America
18. Morphological features :
A shrub, 1.5 to 2 m tall, broad leaves, slightly hairy
or deeply coated with long grey hair, with deep 3-5
lobes.
Nectaries present, stem weak, pedicel 1.0 cm.
long, bracteole size 3.0-3.5 cm, fused at base,
serrations 8-13 in number
. Corolla yellow, size 4.5-5.5 cm, petal spot present,
anther yellow, pollen yellow, stigma protruding, boll
elongated, locules 3, slightly pitted, tip pointed, lint
white
Bolls are large and round and bold 5 to 8 seeds per
locules.
19. Seeds are bald with no Fuzz
Some Varieties: Sujata, Varlaxmi, Andrew etc.
.
Characters of breeding value : Fiber fineness
Key character for identification: Petal spot
present deeply pitted pointedbolls.
Races of G.barbadense: Brasiliense
20. The lint length of Gossypium arobreum and Gossypium
herbaceum is less than about 22mm and are short staple
cotton.
While list length of Gossypium hirsutum is 25 to 30 mm
and are classified as medium to long staple cotton. There
are distinct races within species based on the geographical
distribution.
It is supposed that the present day cultivated arobreum
are derived from this perennial race. The race Cernuum is
suited to high rainfall region of Assam and Bangladesh
. It has produced comilla cotton. The Sinense race has
provided the commercial cultivar of china Korea and
Japan.
The race bangalense has provided the annuals with high
ginning, coarse cotton of Punjab and Sindh regions of
Pakistan, Uttar Pradesh.
The important races of G. herbaceum included Persicum
and Africana which has spread to Iran, Afghanistan and
apart of Africa.
21. In upland cotton G. hirsutum race Marie galnte is large
perennial shrubs or small tree. Highly photo periodic
and spread over Caribbean island, panama, and
northern Brazil. The race Punctatum of upland cotton is
found in Gulf of Mexico.