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Plant Propagation

Plant Propagation. Use of specialized stems, roots and leaves. Reasons for Asexual Reproduction. 1. Fixes superior genotypes Heterozygous verses Homozygous genotype Dominant verses Recessive Complete dominance verses Incomplete dominance. 2. Uniformity of population Plant size

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Plant Propagation

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  1. Plant Propagation • Use of specialized stems, roots and leaves

  2. Reasons for Asexual Reproduction • 1. Fixes superior genotypes • Heterozygous verses Homozygous genotype • Dominant verses Recessive • Complete dominance verses Incomplete dominance

  3. 2. Uniformity of population • Plant size • Growth rate • Flowers • Harvesting will be uniform • 3. Facilitating propagation • Easier to propagate vegetatively than from seeds

  4. 4. Shorter time to flowering • Maintains maturity in the plant instead of having to go from the juvenile to the mature stage. • 5. Can combine more than one genotype • Root stock • Dwarfing, semi-dwarfing – standard root stocks, disease and drought and insect tolerance • Scion • Varietal specificity – 5 kind apple tree

  5. 6. Control phase of development • Juvenile • Plant cannot flower in this stage –easily propagated • English Ivy • Young citrus have thorns • Transitional – inbetween - Acacia juvenile leaves are pinnately compound – mature are long and thin • Mature – capable of flowering

  6. Air Layering • Done on woody plants • Select a suitable branch • Remove some of the leaves • Wound the branch • Apply rooting hormone • Cover with moist sphagnum moss • Enclose moss with plastic wrap • Keep moist

  7. Simple Layering

  8. Compound Layering

  9. Mound Layering

  10. Tip Layering

  11. Specialized Stems and Roots • Geophytes – plants surviving as underground storage organs • Survive • warm/cold conditions in temperate zones • wet/dry conditions in tropical zones • Propagation • by detachable structures called separations • Corms and bulbs • by cutting sections off called divisions • Rhizomes, stems and stem tubers

  12. Structures • Bulbs – short fleshy stem surrounded by thick fleshy scales (leaves) • Outer scales function in food storage • Inner scales act more like leaves • Inside of scales is the vegetative meristem or flowering shoot • Bulblets formed by meristems in axils of scales – when full grown are called offsets • Aerial bublets = bulbils • Underground bulblets = stem bulblets

  13. Types of Bulbs • Tunicate – outer scales become fry and membraneous • Tulip, garlic, onion, daffodile • A. Amaryllis – expanded bases of leaves are used for food storage • B. Tulip – leaves produced on flowering or vegetative shoots • C. Narcissus – has both expanded leaf bases and true scales.

  14. 2. Nontunicate bulbs – no enveloping dry cover – scales are separate and attach at the basal plate • Easily damaged if not handled carefully • Roots form midsummer and persist through the next year • Contractile – shorten and pull the bulb to given level in the ground • Droppers – stolon-like structures growing from the bulb and produce a bulb at the tip.

  15. Growth Stages of Bulbs • Vegetative – roots, stems and leaves • Reproduction – • Induction & flower initiation • Differentiation of flowering parts • Elongation of flowering parts • Anthesis (flowering)

  16. Time of Bloom • Spring Flowering • Tulips flower, the bulb disintegrates while replaced by bulblets – bulblets may or may not be large enough to flower the following year

  17. Daffodils bulbs continue to grow producing offsets that may attain flowering size in a few years.

  18. Flower size and quality are: • Related directly to the size of the bulb • Cool growing conditions favor leaf growth, hence more photosynthates to the bulb increasing its size. • Warm hot conditions result in deterioration of leaves resulting in less energy to the bulb for bulb size increase

  19. Dormant bulbs – the roots disintegrate and the bulb seems dormant. Dig and store in cool dry place • Temperature control of flowering • Moderate temperatures summer and fall result in flower formation • Low but not freezing temperatures promote flower stem elongation • Warming spring temperatures result in flowering

  20. Hyacinth continue to grow but produce few offsets.

  21. Summer flower bulbs – Lilies • Mother bulb is flower producing • Daughter bulbs are formed by the mother bulb initiated last fall from the scales at the base of the stem axis • Vernalization is the cold period required by the bulb to flower • The flower is formed at the tip of the stem during elongation after the leaves are formed

  22. Scaling – bulb scales are separated from the mother bulb – done midsummer after flowering • Yearling – first year bulbs • Commercials are 3 year old yearlings

  23. Scooping – done with hyacinths by scooping out the bottom of the bulb removing the meristem, the tissue left differentiates into new bulblets

  24. Scoring hyacinths by making a knife score on the bottom of the bulb – bulblets form in the score

  25. Corms • Swollen base of a stem axis enclosed by dry, scale-like leaves • Gladiolus

  26. Crocus

  27. Tunic – dry leaves that protect the corm • Terminal shoot – apex of stem that develops into leaves and the flowering shoot • Roots – two kinds – fibrous forming from the base of the corm and enlarged contractile roots that develop from the base of the new corm

  28. Storage – corms are dug – not hardy to killing frost – store best at 40 F in moist peat moss • Light – short day blooming – long day vegetative • Cormel produciton favored by shallow planting • New corms favored by deep plantings • Cormels are planted 1-2” deep where grass like foilage forms the first year • Divisions can be done by dividing the corm making sure that there is a bud in each new section

  29. Tubers • Underground swollen stems that are storage structures

  30. Jerusalem artichoke

  31. Caladium

  32. Eyes – nodes with small buds above leaf scar. Nodes are spirally arranged • Terminal bud – apical end farthest from the crown of the plant

  33. Apical dominance by the terminal bud occurs • Development of the tuber • New shoots obtain energy from tuber • Tuber then disintegrates • Adventitious roots develop at base of main shoot • Main shoot elongates to soil surface forming lateral buds along the shoot that etiolate horizontally into the soil forming stolons

  34. Stolons elongate during long days periods • Tuberization results from inhibition of terminal growth and cell elongation at the subapical end of the stolon. • Short days lengths and lower night temperatures, low mineral content, increased cytokinins and ABA and reduced gibberellins induce tuberization • Tuber size is influenced by the amount of photosynthates available from the leaves • Suberizaton is necessary to prevent drying out and disease infections.

  35. Tuberous Roots • Sweet potato

  36. Dahlia

  37. Rhizomes • Main stem axis grow horizontally slightly below the soil surface Iris

  38. Usually have terminal leaves and flowers

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