Cotton Floral biology and breeding techniques.pdf

This presentation gives information about breeding techniques in cotton. Conventional and non-conventional methods to produce hybrids in cotton is given crisp to easy understanding purpose

1. DEPARTMENT OF GENETICS AND PLANT BREEDING
FACULTY OF AGRICULTURE
ANNAMALAI UNIVERSITY
GPB 511 CROP BREEDING –I (KHARIF CROPS) 2+1
PRESENTATION ON FLORAL BIOLOGY, EMASCULATION AND
POLLINATION TECHNIQUES IN COTTON
SUBMITTED BY
A.VIKRAMAN
1
st
M.S.C AGRI GPB

2. COTTON

3. INTRODUCTION
•Cotton, the king of fibers and it is usually referred as white gold.
•It is soft, fluffy staple fiber that grows in a ball or protective capsule around the seed of cotton
plants of the genus Gossypium.
•Cotton is mainly grown for its lint.
•This is basically spun into yarn or thread that is used in textile industries.
•Seeds and seed oil are important by products.
•The oil of cotton is used for various purposes including cooking, and oil cake is used as
animal feed.

4. ORIGIN AND SPECIES
The genus Gossypium consists of 50 species, out of which 4 are cultivated speciesfor their
spinnable fibres and rest are wild species.
Progenitors : G. africanumandG. raimondi
SPECIES
CENTER OF
ORGIN
Gossypium herbaceum Central Asia
Gossypium arboreum Asia minor
Gossypium hirsutum Central America
Gossypium
barbadense
South America

5. CULTIVATED SPECIES
•Tetraploid cotton (2n =52)
G. barbadense -Egyptian cotton
G. hirsutum-American upland cotton, these two are called as New world cotton
•Diploid cotton (2n = 26)
G. arboreum
G. herbaceum,these two are called as Asian cottonand Old world cotton.
Among these species G. hirsutumis the predominant species which alone contributes about
90% to the global production.

6. FLOWERS OF FOUR CULTIVATED SPECIES
G. herbaceum G. barbadense
G. hirsutum G. arboreum

7. SCIENTIFIC CLASSIFICATION
Kingdom : Plantae
Division : Magnoliophyta
Class : Magnoliopsida
Order : Malvales
Family : Malvaceae
Genus : Gossypium
Species : hirsutumand barbadense(tetraploid)
arboreumand herbaceum(diploid)

8. BOTANY
•Cotton is a warm season crop.
•Perennial (grown as annual though).
•It is woody shrub in nature and it’s a C3 plant,
•Indeterminate in growth and dicot with cotyledonary leaves.
•Cotton plants has very prominent erect stem and leaves are arranged alternately and spirally
around the stem.
•Leaves are petioledand lobed
•The stem and leaves are pubescentand the large leaf veins bear external glands known as
nectariesand excreta sweetish fluid.

9. BRANCHING IN COTTON
There are two typesofbranches observed in cotton :
1)Monopodial branches:
They arise from basal region upto3rd height of the plant,
few in number, they does not bear flowers, also termed as
vegetative branches. They appear as growing straight.
2) Sympodial branches:
They arise from main stem as well as on monopodial branches.
They are many in number, they bear flowers on it, hence termed
as reproductive branches.
The growth pattern of sympodial branches is zig zag pattern.

10. FLORAL DIAGRAM AND FORMULA

11. FLOWER
•Cotton flowers occur singly (solitary)
•Flowers Produced on sympodial branches from
the terminal buds.
•Base of flower surrounded by three leaf like
triangular bracts (epicalyx).
•The calyx is reduced to a small cup shaped
structure with five lobes

12. COROLLA
•Bright yellow
•5 petals
•polypetalous
•In interior petals twisted to base
of staminal column

13. ANDROECIUM
•Numerous stamens
•Filaments are united to form a tubular
staminal column (monadelaphous) around
the style
•Anthers arranged in five rows on staminal
tube

14. GYNOECIUM
•Pistils consists of 3-5 carpels corresponding to locules in fruit
•Ovary-superior
•Slender style with varying length
•Style -Single
•Ovary develops into a capsule or boll
•Each locule have 8-12 ovules
•5-9 ovules matures

15. ANTHESIS
•Twisted corolla emerges from the bracts
•Variation in time of flower opening. Maximum flower opening is around 8 to 10am.
•Temperature also affects flower opening.
•Stigma becomes receptive soon after flower opening.
•Stigma receptivity -24 hrs.
•Pollen viability -12 hrs

16. POLLINATION
•Cotton is basically self Pollinated crop because pollen is shed directly on stigma.
•Cross pollination is promoted by insects, mostly honey bees.
•Cross pollination ranges from 5-30% sometimes exceeds 50%
•Hence cotton is an often cross pollinated crop.
•The slighted elevated position of the stigmatic surface leads to
the occasional cross pollination.
•In insect pollination, particularly honey bee pollination can
aid in the process and result in higher yields and better
quality lint.

17. FERTILIZATION AND FRUIT SET
•Fertilization is maximum if pollination occurs at the time of anthesis
•Fertilization is completed in 36-40 hrsafter pollination.
•6 to 8 weeks from first flower to ripe fruit.
•Fruit is boll.
•Young fruit or fruit bud is called a square.
•Under optimum condition it requires 50 days for
a boll to “open” after pollination occurs.

18. SELFING TECHNIQUES
•Paper bag method
A small paper cover is put over the mature flower bud
before anthesis and kept for 2-3 days.
•Mud smear method
A mature flower bud is selected and the corolla is tied
with a piece of thread.
In order to keep the threads in position apply a bit of
wet clay over the knot.
This will avoid contamination of the stigmatic surface
by foreign pollen.

19. HBRIDIZATION METHODS
•The hybrid cotton is developed through two methods
Conventional method ( Emasculation and Pollination)
1)Doakmethod or thumbnail method
2)Surat method or Pinching off of top of corolla
3)Copper straw or Straw tube method
4)Petal removal and brushing off anthers
Non conventional method ( Male sterility based)
1)Genic male sterility system
2)Cytoplasmic genic male sterility system

20. CONVENTIONAL METHODS
•DEVELOPMENT OF HYBRIDS
I.Identification and growing of male and female parents
II.Emasculation of female parent
III.Pollination of female parent with identified pollen
In diploid cottons conventional methods is highly uneconomicalsince boll setting is low due
to small flower size and brittle pedicel.
However, the seed of conventional hybrids is very expensive as several labourers are engaged
for emasculation

21. EMASCULATION METHODS
•Flower buds which are likely to open the next day are selected for emasculation for which the
best time is after 1p.m.
1) DOAK METHOD OR THUMBNAIL METHOD
The most successful method with 40 to 50% or more
seed setting.
A mature flower bud is selected from which the corolla
is removed and total staminal column is peeled off by
making a narrow cut at the lower portion of flower bud
by thumbnail with one jerk twisting action.
Care should be taken not to injure the ovary.
After the emasculation, cover the flowers with red paper
covers.
This is called Doak'smethod.

22. 2) SURAT METHOD OR PINCHING OFF OF TOP OF COROLLA
The top portion of flower bud is pinched off using thumb and first finger nails by hand.
The tip of stigma get slightly exposed and the bud is covered with mud.
As the buds mature the stigma tip extend sufficiently for enabling pollination.
In genotypes where stigma tip excertionis comparatively low, the entire corolla is
removed and lint dipped in mud is applied on unopened anther sacs. The pollen is
applied next morning (Mehta et al, 1983).

23. 3) SODA STRAW / COPPER STRAW/ STRAW TUBE METHOD
The top of the corolla of bud is pinched off and a piece of straw tube is used by inserting
it on the style.
It separate all anthers from anther column to stigma.
Leaving the tube in the same position till pollen is applied next morning(Hays et al,
1953).
Relatively more time is required for inserting the straw tube exactly on the style so that
anthers would get dislodged.

24. 4) PETAL REMOVING AND BRUSHING OF ANTHERS
Only flower petal is removed by thumb nail method.
The anthers brushed off by lightly touching and moving the thumb and first finger down
and up along the staminal column.
A light tapping of the flower pedicel will dislodge any anthers sticking in the bracts.
This method is useful in herbaceumcotton buds where anthers are of granule type, get
removed very easily and drop to the ground.

25. POLLINATION OF FEMALE PARENT WITH IDENTIFIED
MALE PARENT
•Emasculated buds are covered with red colored tissue bags for easy identification.
•Emasculated buds are pollinated the next day between 8 and 11 am.
•The crossed flowers are again covered with a white colored tissue bag.
•A thread is tied to the pedicel for identification of crossed bolls at the time of picking.

26. CONVENTIONAL HYBRIDS
India releases the worlds first hybrid cotton “H4” from main Cotton Research Station ,Surat
of Gujarat Agricultural University (G.A.S) in 1970 by Dr.C.T. Patel.
It is intra-specific hybrid or intra-hirsutumhybrid.
Intra-specific : ( G. hirsutumX G. hirsutum) –Gujarat 64 X American nectariless= H4
World’s first inter-speciccotton hybrid “ Varalaxmi” was released from U.A.S., Dharwad by
DR.B.H. Katarkiin 1972.
Inter-specific : ( G. hirsutumX G. barbadense ) –Laxmi X SB 289E = Varalaxmi
G. Cot DH 7 –first Asiatic cotton hybrid ( G. herbaceumX G. arboreum).

27. NON CONVENTIONAL METHODS
With a view to reduce the cost of hybrid seed, efforts were made to develop hybrids using
male sterile system
1) Genic male sterile system ( GMS)
2) Cytoplasmic genic male sterile system ( CGMS)
Male sterility was reported for the first time in cotton by Justus and Leinweberin 1960.
In India, male sterility in arboreumcotton has been reported by Singh and Kumar,1993;
Meshramet al., 1994.

28. 1)GENIC MALE STERILE SYSTEM
There are various male sterility genes, both dominant as well as recessive, identified in
G. hirsutum, G. barbadense and G. arboreumcotton.
Recessive sterility is controlled by both single as well as duplicate genes.
Dominant sterility is controlled by single gene only.
The World’s first genetic male sterility (GMS) based hybrid –“Suguna” was released in
1978 from Central Institute for Cotton Research, Regional Station, Coimbatore. (Upland
Cotton for Tamil Nadu).
However, this hybrid could not become popular in the state of Tamil Nadu, mainly due to poor
yield than conventional hybrids.

29. 2) CYTOPLASMIC GENIC MALE STERILE SYSTEM
The cytoplasmsof three diploid species, viz.,G. anomalum, G. harknessiiand G.arboreum
interact with nuclear genes of G. hirsutumand produce male sterility.
The cytoplasm of G. arboreumand G. anomalumare heat-sensitive and therefore less stable.
The cytoplasm of G. harknessiiand genome of G.hirsutuminteraction produce stable and
dependable cytoplasmic male-sterility in cotton.
The first CGMS based cotton hybrid –PKV Hy3 was released for commercial cultivation in the
Vidarbha region of Maharashtra which was developed at Cotton Research Station of Punjabrao
Deshmukh Krishi Vidyapeeth (PDKV), Akola in 1993.
However, yield of this hybrid is also 10-15 lower than conventional hybrid developed using the
same parents.

30. GENETICALLY MODIFIED COTTON
•The crops in which one or many traits are altered through Genetic Engineering is called Gm
crops. i.e. Bt. Cotton developed against cotton boll worms.
•Bacillus thuringensisis a soil bacterium that produces producescrystalline proteinthat
produces delta endotoxin.
•This toxin affect the larval midgut releasing toxic fragments causes gut paralysis.
•The gene responsible for this effect is Cry-1Ac and Cry 2 Ab.
•Mahycocollaborated with Monasntoto develop Bt. Variety Bollgourd-1 using Cry-1 Ac gene.
•Recently Bt. Cotton variety developed as Bollgourd-IIhaving both genes of Cry I Ac and
Cry 2 Ab gene. Which is known as ‘ second generation of Btcotton’.