Cotton

Floral biology and breeding techniques

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2. COTTON
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3. INTRODUCTION
•Scientific Name:Gossypium spp
•Family : malvaceae
•Chromosome No.: 2n =26, 4n=52
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4. IMPORTANCE
•Cotton constitutes 85% of raw material for textile industry
•Around 80% of the pesticide is consumed by cotton only
•Cotton seed oil used in lubrication industry
•Seed contain alkaloid gossypol
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5. GEOGRAPHICAL
DISTRIBUTION
•Cultivated all over the world
•Area : 7-8 m ha
•Production : 2.6 m bales
•India ranks first in area and second in production
•China first in production
•Leading countries are India,USA, Russia, China, Brazil
•All the four species are growing in India
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6. ORIGIN & EVOLUTION
Genus Gossypiumis originated in Central Africa
•G. arboreumandG. herbaceumorigin in Asia
•G. barbadenseorigin in Egypt G. hirsutum
origin in America
Ancestor : G.herbaceum(AA) and G.raimondii(DD)
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7. Scientific classification
•Kingdom :Plantae
•Order : Malvales
•Family :Malvaceae
•Subfamily :Malvoideae
•Tribe :Gossypieae
•Genus :Gossypium
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8. SPECIES
•G. arboreum
•G. herbaceum
•G. hirsutum
•G. barbadense
•G. australe
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•G. darwinii
•G. sturtianum
•G.thurberi
•G. tomentosum
•G. raimodii

9. CYTOGENETICS
•In Cotton there are 6 genomic groups A,B,C,D,E,F.
•B,C and F genomic groups found in India
C genome is found in Australia and D in America
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10. BOTONY
•Cotton plant has very prominent errect stem
leaves are arranged alternately and spirally around the
stem leaves are
petioled and lobed The stem and
leaves are pubscent the large leaf veins
bear external glands known as nectaries and excreat a
sweetish fluid
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12. A cotton plant with leaves removed shows the straight growth habit
of the main stem and the vegetative branches.
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13. A fruiting branch with leaves removed shows
its zig-zaggrowth habit.
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14. FLORAL BIOLOGY
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FLORAL
BIOLOGY
FLORAL
MORPHOLOGY
FLORAL
ANTHESIS

15. Anatomy of mature flower
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18. Stages of cotton development
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19. FLOWER
•Cotton flowers occur singly (solitary)
•Produced on sympodialbranches 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
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20. Cont…….
The branching of cotton 2 types a) vegetative or
monopodialbranching b) fruiting or sympodial
branching Vegetative stracturallylike main stem
sympodialbranches bears flowers and fruits
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21. COROLLA
•Bright yellow
•5 petals
•Gamopetalous
•In interior petals united to base of staminal column
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22. ANDROECIUM
•Numerous stamens
•Filaments are united to form a tubular staminal
column (monadelaphous) around the style
•Anthers arranged in five rows on staminal tube
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23. GYNOECIUM
•Pistils consists of 3-5 carpels corresponding to loculesin fruit
•Ovary –superior,
•Slender style with varying length
•Style –Single
•Ovary develops into a capsule or bole
•Each loculehave 8-12 ovules
•5-9 ovules matures
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24. ANTHESIS
•Twisted corolla emerges from the bracts
•Variation in time of flower opening Maximum
flower opening –8 to 10a Temperature also affects
flower opening
•Stigma becomes receptive soon after flower opening
•Stigma receptivity –24 hrs
•Pollen viability –12 hrs
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25. POLLINATION
•Self Pollinatedcrop because pollen is shed directly
on stigma
•Cross pollination due to insects
•Cross pollination ranges from 5-25% sometimes
exeeds50%
•Hence cotton is an often cross pollinated crop
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26. FERTILIZATION & FRUIT SET
•Maximum if pollination is at the time of anthesis
•Fertilization is completed in 36-40 hrs after
pollination
•6 to 8 weeks from first flower to ripe fruit
•Fruit is boll
•Young fruit or fruit bud is called a square
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27. SELFING TECHNIQUES
•Paper bag method
•Ring method
•Mud smear
•Other methods
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29. CROSSING TECHNIQUES
•Includes
•Emasculation
•Pollen collection
•Artificial pollination
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30. SELECTION OF FLOWER BUD
•. The crossing work is
initiated after one week of
flower initiation.
•The flower buds of proper
stage (buds which are likely
to open the next day) are
selected for emasculation.
•Such buds have generally
cream colourand are well
developed.
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32. Emasculation and crossing
techniques
•Hand emasculation and crossing
•Humphrey and tuller method
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34. EMASCULATION
•An incision is made at the bottom near calyx
•A circular shallow cut is given so that the corolla and
stamen tube surrounding style come off
•Bag with butter paper and tag it
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35. Hand emasculation and crossing
•Done in female parent on the evening
•Using nails of thumb of both the hands the staminal
column along with anthers and attached petals are
removed
•During next day morning the anthers of male
flowers are rubbed against the stigma of emasculated
flower and then bagged
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36. POLLEN COLLECTION
Collect flowers from the male parent
during early morning hours
Collect pollen in straw tube
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•Pollinate next morning
between 8am to 1pm
•Insert the straw tube
containing pollen, on
emasculated flower stigma

37. Fertilization and fruit set
•In hand emasculation 65-70% success will be seen
•After fertilization white flowers turn to pink or red
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