cotton

COTTON

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INTRODUCTION

• Scientific Name :Gossypium spp

• Family : malvaceae

• Chromosome No. : 2n =26, 4n=52

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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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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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ORIGIN & EVOLUTION

Genus Gossypium is originated in Central Africa

• G. arboreumand G. herbaceum origin in Asia

• G. barbadense origin in Egypt G. hirsutum

origin in America

Ancestor : G.herbaceum (AA) and G.raimondii (DD)

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Scientific classification

• Kingdom :Plantae

• Order : Malvales

• Family :Malvaceae

• Subfamily :Malvoideae

• Tribe :Gossypieae

• Genus :Gossypium

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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

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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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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A cotton plant with leaves removed shows the straight growth habit

of the main stem and the vegetative branches.

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A fruiting branch with leaves removed shows

its zig-zag growth habit.

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FLORAL BIOLOGY

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FLORAL

BIOLOGY

FLORAL

MORPHOLOGY

FLORAL

ANTHESIS

Anatomy of mature flower

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Stages of cotton development

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FLOWER

• Cotton flowers occur singly (solitary)

• 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

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Cont…….

The branching of cotton 2 types a) vegetative or

monopodial branching b) fruiting or sympodial

branching Vegetative stracturally like main stem

sympodial branches bears flowers and fruits

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COROLLA

• Bright yellow

• 5 petals

• Gamopetalous

• In interior petals united to base of staminal column

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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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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 bole

• Each locule have 8-12 ovules

• 5-9 ovules matures23

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 hrs24

POLLINATION

• Self Pollinated crop because pollen is shed directly

on stigma

• Cross pollination due to insects

• Cross pollination ranges from 5-25% sometimes

exeeds 50%

• Hence cotton is an often cross pollinated crop

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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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SELFING TECHNIQUES

• Paper bag method

• Ring method

• Mud smear

• Other methods

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CROSSING TECHNIQUES

• Includes

• Emasculation

• Pollen collection

• Artificial pollination

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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 colour and are well developed. 30

Emasculation and crossing

techniques

• Hand emasculation and crossing

• Humphrey and tuller method

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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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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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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

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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cotton

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