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8-Pollination & Fecundation.ppt

  1. Pollination and Fruit setting Week - 3 Lecture 1
  2. Flower Flower is a shoot of determinate growth with modified leaves that is supported by short stem Flower parts Sepals/calyx Petals/corolla Androecium Gynoecium Perianth Pedicle Peduncle Brackets Receptacle/thalamus Enlarged apex of the flower stalk or head of the pedicle from where the flower parts arise
  3. • Perianth: External row of petals or sepals • Pedicle : stalk of flower is called … • Peduncle: stalk of inflorescence • Bracts: A bract is special leaf, which bears a flower or cluster of in its axil. Chief function is to protect the flower-buds from the sun and rain • Thalamus: Enlarged apex of the flower stalk or head of the pedicle from where the flower parts arise
  4. Sepal Petal Ovary Stigma Filament Anther Pedicle Receptacle Style
  5. Types of flowers Complete flower (A complete flower is a flower that has all four parts of the flower (sepals, petals….. ) Example: Citrus, Apple, Tomato, Peach, Plum, Pear Incomplete flowerA flower lacking sepals, petals, stamens, or pistils. Example: Date palm (with out petal)
  6. Types of flowers • Perfect flower (both sex organs ) • Example: Citrus, Apple, Tomato, Peach, Plum, Pear • Imperfect flower (a unisexual flower with only stamens or only pistils ) • Example: Papaya, date palm
  7. Types of flowers Pistillate Example: Date palm Staminate Example: Walnut, Pecan nut (Catkins) Hermaphrodite Example: Citrus, Guava, Apple Solitary (flower singly) Example: Peach, Clustered flower (in group) Example: Mango, Apple, pear, grapes
  8. Determinate flowers: Inflorescence in which terminal flowers open first. Example: Apple Indeterminate flowers: The inflorescence in which the basal flowers open first and flower bud continue to develop. Example: Tomato, Pear, Cucumber Hypogynous: If the stamens, petals and sepals are attached to the receptacle below the ovary the ovary is superior and flower is hypogynous. Example: Citrus, Grapes, Kiwi fruit Types of flowers
  9. Ovary Position
  10. Ovary Position
  11. Zygomorphic: if flower can be divided into two equal parts by cutting it into only one longitudinal plane.
  12. Basal placental arrangement: Ovules are attached at the base of ovary in side the locules. Example: Avocado Apical placental arrangement: Ovules are attached at the apex of ovary in side the locules. Example: Peach Placental arrangement Attachment of ovule to the ovary walls through strand or filament is called placental arrangement
  13. Placentation Peach Avocado
  14. Embryo Sac: Cavity inside the ovule is called embryo sac Integument: Walls of the mature embryo. These two walls form the outer covering of seed. (Testa and Seed Coat). Example: Pear, Blue berry
  15. Pollination Successful transfer of pollen from anther of a stamen to the receptive stigma of an overy is known as --------  Availability of adequate and viable pollen  Efficient transfer of pollen when stigma is most receptive  Pollen tube must grow & enter the embryo sac  Union of male and female gametes Stimulus for fruit development
  16. Transfer of pollen-grains on stigma with in the same flower or an other flower of the different plant of the same variety. It occurs in homogamous flower; bisexual flowers in which pollen grains are shed when the stigmas are ready for reception Example Peach, Avocado, Fig Self pollination ( autogamy)
  17. Self fertility/self fruitfulness Ability to set and yield a commercial crop with its own pollen. Self sterility/ self unfruitfulness Inability to set and yield a commercial crop with its own pollen.
  18. Pollination and fruit setting problems 1. Flower opening 2. Pollen dehiscence 3. Pistil receptivity 1- Flower opening  Day lily flower opening in early in morning 6-7 am to 8-9 pm. Total duration of flower opening is 12-14 hrs. Flower open at morning and close evening  Poppy flower open for 2 days  Apple flower open for 2-5 days  Orchids flower open for 80 days Flower opening in different plant ranges from few hours to many days
  19. 2- Pistil receptivity Receptivity of guava pistil is 48 hours after flower opening Date palm about 4 days after opening of spathe and about after 8 days receptivity finishes Fertilization in plum takes place even after 7 days of flower opening Guava stigma remain receptive for 2 days In Mango stigma remain receptive for 4 hours Mostly those flowers which have abundance of pollen are wind pollinated and do not open for longer duration Whilst those flowers have little pollen remain open for larger duration and are insect pollinated
  20. 3- Pollen dehiscence The rupturing of anther either length wise or apically and to remove the pollen is called pollen dehiscence Pollen dehiscence and stigma receptivity occurs simultaneously But it is not universal truth that during blooming the stigma will always remain receptive Temperature and humidity are two factors which effect pollen dehiscence Under normal conditions pollen viability ranges form few hrs to few days Guava 4 hrs
  21. Cross pollination( allogamy) • The transfer of pollen from anther of the flower of one variety to the stigma of flower of another variety is known as cross pollination
  22. Prerequisites of cross pollination • Self incompatibility • Sterility • Dichogamy (non-synchronous maturation of pollen grains and ovules in hermaphrodite or unisexual flowers on a single plant) • Heterostyly ( variation in length style 0
  23. Fecundation/Fertilization Union of male and female gametes
  24. Fruit setting Fruit setting refers to the initial and first appreciable swelling of ovary occurring shortly after the period of petal fall. Its is generally accompanied by some thickening of pedicle or peduncle. Vegetative response to pollination and fruit setting Flower that has not set are turned yellow, withered and fall off. Fertilization follow the growth and development of embryo and endosperm with in the ovary and surrounding ovary walls, some time torus and other adjoining tissues.
  25. Types of drops First drop or Blossom drop: Occurs soon after blooming. Usually flowers with defective parts drop. Second drop or initial fruit drop June drop (Button drop) Preharvest fruit drop: In consist of drop of un-pollinated flower and very young fruits. Due to any abiotic or environmental stress. Small button size fruit drop. Some time in citrus called as natural load sharing Fruit is mature and about to ripe. Economic loss to the grower.