1. METHODS OF ASEXUAL PROPAGATION
CUTTINGS
LAYERING/CIRCUMPOSING
GRAFTING
BUDDING

2. Methods of Asexual Propagation
CUTTINGS

3. CUTTINGS
Cuttings – pieces of vegetative material from any of the three primary plant organs – root, leaf and stem used to produce a new plant.
Types
1. stem tip (terminal) cuttings
2. stem cuttings – taken from soft-wood,
hard wood and semi-hard wood
3. Leaf cuttings – leaf vein, leaf bud and petiole
4. Root Cuttings

4. Biology of Adventitious Root Formation (Cutting)
Propagation by stem, leaf, shoot tip and root cuttings require only new adventitious root system to be formed.
This is dependent on the plant cells to dedifferentiate.
That is the capability of the cell to initiate a new meristematic growing point.

5. Biology of Cuttings Roots of cuttings are wound-induced
Roots are formed de novo
The root regeneration process includes three steps:
1. The outer injured cells die, the wound is sealed with suberin and the xylem plugs with a gum

6. Root Generation Process
2. Livings cells divide after a few days and a layer of parenchyma cells (callus) forms a wound periderm
3. Certain cells in the vicinity of vascular cambium and phloem begin to divide and initiate de novo adventitious roots

7. Cross-Section of a Mature Stem

8. Biology of Propagation by Cuttings
Direct root formation from Vascular Tissue
Indirect root formation from callus
Difficult to root species often have a ring of sclerenchyma cells that block root penetration
Difficult to root species often produce callus first and then roots from the callus
(Indirect root formation)

9. Stem Structure and Rooting

10. Biology of Propagation by Cuttings
Leaf Cutting
Limiting Factor in Leaf Cutting Propagation is the Formation of adventitious buds Not Adventitious roots.
Origin of new shoots and roots from:
Preformed 1◦ meristems
Wound induced 2 ◦ meristem

11. Biology of Propagation by Cuttings
Developmental process of rooting has two Stages:
Root initiation
i) auxin-active: auxin is required for root formation
ii) auxin-inactive: auxin not required for roots
2. Root elongation – auxin not required

12. High auxin/low cytokinin ratio favours adventitious rooting
Low auxin/high cytokinin ratio favours adventitious buds/shoots
Difficult to root plants often have high cytokinin levels

13. Factors Affecting Regeneration of Plants From Cuttings
Management of stock plants to maximize cuttings.
- Selection and maintenance of source material
- Manipulating the environmental conditions and physiological status

14. Maintenance of Stock Plants
- Maintain stock plant in juvenile/transition phase - Reversal from the mature to juvenile/transition phase - Re-establish high rooting potential - < 50 % rooting undesirable

15. Rejuvenation of stock Plant
Ease of adventitious root formation declines with age of parent stock
Transition from the Juvenile to mature stage – phase change or ontogenetic aging

16. Select a Healthy Parent Stock

17. Simple Cutting Procedure
If the stem has large leaves, cut the two largest ones in half. This means the cutting will lose less moisture from its leaves, allowing it to put more energy into forming roots.

18. Types of Hard Wood Cutting
Straight
Mallet
Heel

19. Plant Produce by Cutting

20. The Biology of Cuttings

21. Minimum requirements for Cuttings
Plant factors;
1. nutritional status of the plant
2. Hormone level
3. Juvenility
4. Position of the plant part

22. Minimum requirement Environmental factors; Darkness Light Temperature
Moisture
Time of day and year cutting is taken
sanitation

23. Layering/Circumposing

24. Layering/Circumposing
Describes as modified cutting – roots are generated on the stem or root of a plant before is completely cut away from the parent plant
The newly rooted plant will survive independently of the mother plant.

25. Biology of Layering
Accumulation of photosynthates and hormones in the rooting area are important to the success of root during layering
Light exclusion
Phloem interruption – breaks the flow of food from the upper stem to the girdled portion
Girdling reduces water conductivity

26. Types of layering Natural layering – tip, runners, suckers, crowns.
Simple layering – air layering, trench layering, mound layering, compound layering.

27. Simple layering .
can be accomplished by bending a low growing, flexible stem to the ground

28. Tip Layering

29. Compound (serpentine) Layering

30. Mound Layering

31. Air-Layering

32. Layering

33. Minimum requirement - layering
An appropriate rooting medium
An appropriate material for holding the medium
Adequate moisture
Healthy plant source

34. Grafting

35. Grafting
Parts of two different plants are joined so that they continue their growth as one plant.
To accomplish this; one of the two plants serves as the bottom (in contact with soil) – rootstock
The other serves as the top part – scion. The scion is being propagated and the only one allowed to grow.

36. Strategy in grafting
Align tissues so that the vascular transport is restored between the two parts (scion and stock).
Healing starts with the production of callus (undifferentiated cells).
This occurs in the cambium region of the two parts.
Followed by further differentiation of cells to form vascular tissue, completing the repair and allows vascular transport.

37. Strategy in Grafting
Correct polarity is important to the success of grafting – proximal end of the scion should be inserted into the distal end of the rootstock
Cell to cell recognition must occur as part of the adhesion process

38. The wound response is followed by the dissolution of the necrotic layer.
There is direct cellular contact of plasmodesmata in the callus bridge that connects the grafting partners

39. Uses of grafting technique
To propagate plants difficult to produce from cuttings.
Provide disease resistance to a susceptible but desirable cultivar.
To rapidly increase the number of a desirable cultivar.
To change plant size and vigour

40. Uses of Grafting technique
To repair damaged plant parts
To change plant form
Virus indexing

41. Types of Grafting Detached- scion grafting; - whip and tongue grafting
- cleft (wedge and saddle) grafting
- bark grafting
Approach grafting
Side grafting

42. Types of grafting
Bridge grafting
inarching

43. Saddle graft

44. Side veneer graft

45. Requirement for success
Plant conditions
1. Compatibility
2. Diameter of the parts
3. physiological state
4. alignment of tissues
Environment
Operator

46. Flow chart of Grafting

47. Budding

48. Budding
A form of grafting in which the scion consists of a single vegetative bud.
The difference between budding and grafting is that bud uses a single bud as the scion, whereas grafting uses pieces of planting material consisting of several buds.

49. Types of budding
T – budding
Patch budding
Chip budding

50. Removing the bark shield with the bud attached.

51. Bark shield with bud inserted into T cut.

52. Wrapped bud

53. Minimum requirement
Actively growing rootstock (i.e. in spring, late summer or fall)
Some of the factors in grafting.

54. Step 1 and 2

55. Step 3 and 4

56. Step 5 and 6

57. Step 7

58. Step 8

59. Reasons for Budding Change varieties or cultivars
Optimize cross-pollination and pollination
Take advantage of particular rootstocks
Perpetuate clones
Produce certain plant forms

60. In Class Assignment
Read up on the types of each propagation technique (eg.) Types of budding, layerng etc.
Read up on Propagule, Parthenocarpy
Apomixis, chimeras, mutation, virus indexing

61. Support Site
- United States.

62. Reference
Acquaah, G. (2009). Horticulture: principles and practices 4th ed.
Hartman, H., etal. (1979). Plant Propagation: principles and practices 6th ed.

63. THE END
Courtesy: L. Clarke, and
M.Gager, CASE