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Vegetative Propagation | ExamplesSeed vs. Vegetative Propagation | Artificial Propagation

Vegetative Propagation of Flowering Plants

Vegetative Propagation

Asexual formation of new plants that develop from multicellular structures that grow by mitosis and become separated from the parent plant.


Examples
 

Stem Example of Vegetative Propagation: potato tuber

Textbook Diagram: Potato Plant and its Tubers

  • The potato tuber is a stem modified for winter survival and asexual reproduction.
  • The tuber ‘germinates’ in spring growing into a new plant.
  • The potato plant forms many underground stem tubers during the growing season.
  • The aerial parts die away at the end of the season and the tubers survive.

Root Example of Vegetative Propagation: root tuber

Textbook Diagram: Root Tubers of Orchid or Dahlia

  • The root tuber is a root modified for winter survival and asexual reproduction.
  • Some of the roots become greatly swollen with food reserve.
  • The aerial parts die down at the end of the season.
  • The root tubers survive each with the base of a stem containing buds.
  • Buds on the stem bases germinate in spring forming new plants fuelled with food from the tuber.

Leaf Example of Vegetative Propagation: plantlets of Bryophyllum (‘mother of thousands’)

Textbook Diagram: Bryophyllum plant.

  • Small plants develop at the margins of the leaves.
  • The plantlets fall off the leaf and will grow into a new plant if the conditions are suitable.

Bulb Example of Vegetative Propagation: onion bulb

Textbook Diagram: longitudinal section of onion bulb.

  • The onion bulb is a short stem carrying fleshy leaves, axillary buds and a terminal bud.
  • The terminal bud of the bulb develops into a new plant in the growing season.
  • At the end of the season food is transported to one or more axillary buds.
  • These buds become swollen with food each forming a new bulb.


Comparing Reproduction by Seed and Vegetative Propagation

  • Greater genetic variation by seed – population is better adapted to survive environmental change.
  • Greater dispersal by seed – less competition and greater colonisation of new habitats.
  • Greater number of offspring by seed: greater success in local habitat
  • Less food reserve per individual by seed: reduced success on germination.
  • Genetic similarity by vegetative propagation: more successful colonisation of stable habitat.


Artificial Propagation  

Cuttings

Textbook Diagram: cutting set up.

  • Cutting is the detachment of part of a plant to grow a new plant.
  • Young healthy lateral branches are suitable.
  • Some of the leaves may be removed to reduce transpiration and so conserve water.
  • Place cut end of stem into well-drained aerated compost.
  • A new root system develops at the cut end.
  • Advantages: fast, easy, cheap and new plants are genetically identical to parent plant.

Grafting

Textbook Diagram: grafting procedure.

  • Grafting produces new plants by joining a branch of the desired shoot system (scion) of one plant onto the vigorous root system (rootstock) of another.
  • Complementary shaped cuts are made in stem of scion and rootstock.
  • The scion stem is joined to the rootstock stem.
  • The meristematic tissue of scion and rootstock are in contact and its growth unites them.
  • Advantages: fast, flowers and fruit are identical to the scion parent.

Layering

  • A young healthy stem is bent into a small hole with the terminal bud above soil level.
  • The hole is filled with soil.
  • A new root system develops at an underground node.
  • The terminal bud forms a new shoot system.
  • The new plant can then be separated from the ‘parent stem’.

Tissue Culturing (Micropropagation)

Textbook Diagram: tissue culturing set up.

  • Remove a very small sample of meristematic tissue from the tip of a branch.
  • This tissue sample is likely to be free of virus infection.
  • Place the tissue sample on sterile nutrient agar in a dish.
  • Plant growth regulators can be added to stimulate and control development.
  • A plantlet will grow from the tissue sample.
  • Transfer to a suitable compost for further growth.
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