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Cotton
1. Cotton is an important crop that provides over 80% of the raw material for the textile industry. It is cultivated around the world, with India and China being the top producers. 2. Cotton plants belong to the genus Gossypium and have four domesticated species. The plants have prominent erect stems with alternately arranged leaves and flowers that develop into bolls containing seeds. 3. Cotton flowers are pollinated through self-pollination and some cross-pollination by insects. After fertilization, the ovaries develop into bolls over several weeks that contain cotton fibers and seeds at maturity.
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Cotton
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- 3. INTRODUCTION • Scientific Name:Gossypium spp • Family : malvaceae • Chromosome No. : 2n =26, 4n=52 3
- 4. IMPORTANCE • Cotton constitutes85% 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 4
- 5. GEOGRAPHICAL DISTRIBUTION • Cultivated allover 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 5
- 6. ORIGIN & EVOLUTION GenusGossypium 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) 6
- 7. Scientific classification • Kingdom:Plantae • Order : Malvales • Family :Malvaceae • Subfamily :Malvoideae • Tribe :Gossypieae • Genus :Gossypium 7
- 8. SPECIES • G. arboreum •G. herbaceum • G. hirsutum • G. barbadense • G. australe 8 • G. darwinii • G. sturtianum • G.thurberi • G. tomentosum • G. raimodii
- 9. CYTOGENETICS • In Cottonthere 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 9
- 10. BOTONY • Cotton planthas 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 10
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- 12. A cotton plantwith leaves removed shows the straight growth habit of the main stem and the vegetative branches. 12
- 13. A fruiting branchwith leaves removed shows its zig-zag growth habit. 13
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- 15. Anatomy of matureflower 15
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- 18. Stages of cottondevelopment 18
- 19. FLOWER • Cotton flowersoccur 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 19
- 20. Cont……. The branching ofcotton 2 types a) vegetative or monopodial branching b) fruiting or sympodial branching Vegetative stracturally like main stem sympodial branches bears flowers and fruits 20
- 21. COROLLA • Bright yellow •5 petals • Gamopetalous • In interior petals united to base of staminal column 21
- 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 22
- 23. GYNOECIUM • Pistils consistsof 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 matures 23
- 24. ANTHESIS • Twisted corollaemerges 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 24
- 25. POLLINATION • Self Pollinatedcrop 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 25
- 26. FERTILIZATION & FRUITSET • 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 26
- 27. SELFING TECHNIQUES • Paperbag method • Ring method • Mud smear • Other methods 27
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- 29. CROSSING TECHNIQUES • Includes •Emasculation • Pollen collection • Artificial pollination 29
- 30. SELECTION OF FLOWERBUD • . 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
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- 32. Emasculation and crossing techniques •Hand emasculation and crossing • Humphrey and tuller method 32
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- 34. EMASCULATION • An incisionis 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 34
- 35. Hand emasculation andcrossing • 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 35
- 36. POLLEN COLLECTION Collectflowers from the male parent during early morning hours Collect pollen in straw tube 36 • Pollinate next morning between 8am to 1pm • Insert the straw tube containing pollen, on emasculated flower stigma
- 37. Fertilization and fruitset • In hand emasculation 65-70% success will be seen • After fertilization white flowers turn to pink or red 37
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