Module 8: Grafting Flashcards
What is grafting?
Art of joining parts of plants together so that they will unite and continue their growth as one plant
What is a scion?
Part of the graft that will grow into the top portion of the plant
Often a piece of stem tissue, several inches long, 2 to 4 buds
What is a rootstock?
Part of the graft that will become the root system
What are other terms for rootstock?
Understock, stock
What is the purpose of grafting?
To propagate plants when cuttings are difficult to root and to make use of a rootstock that has desirable qualities
Controlling size of plant (dwarf species)
What is a whip and tongue graft?
Used to graft material 6 to 13mm in diameter
Graft is buried in a moist material for 2-3 weeks to encourage callusing in the union
What is the interstock?
Portion taken from another plant and used in cases where the scion and rootstock are not compatible
So interstock is inserted
So graft has 3 parts
What is important in grafting?
Vascular cambium of scions need to align with vascular cambium of rootstock
What is a cleft graft?
Used mostly in top grafting in late winter and early spring
6-13 mm diameter scions are inserted into 8-19cm diameter branch stubs
What is a side veneer graft?
Allows rootstock to be used again in case the first graft doesn’t work
Grafted branch will grow at a slight angle
What is a splice graft?
One of the simplest grafts done to plants that can heal rapidly
Generally limited to indoor grafts
What is a saddle graft?
Not used as often because it is more time consuming
Also good for rhododendrons or plants with large stems
It’s important that the base of the scion doesn’t separate from the wood
What is a cutting/twig graft?
Graft a leafy scion to a leafy cutting that’s unrooted
Used occasionally with citrus and rose
Rootstock must be treated with auxin and inserted in a rooting medium in a fog chamber to prevent loss of moisture and to encourage root growth
What is a double worked graft?
Includes an intermediate piece of stem (interstock) between the scion and rootstock to overcome any incompatibility issues producing dwarf trees
What is root grafting?
Scion is grafted directly to a short root, then planted
What is top grafting/top working?
Used to change the cultivar of a fruiting tree or vine
What is bridge grafting?
Used to repair the injured trunk of a tree
What is inarching grafting?
Used to replace a damaged root system
What is bark grafting?
Used for top grafting and done in spring when the bark peels easily from wood
Very easy to conduct and is widely used
What is bench grafting?
Indoor grafting conducted in late Winter/early Spring using potted rootstock
Usually whip and tongue grafts are used
What are grafting machines?
Used in grape grafting and making of fruit tree root grafts because it’s quicker to use machinery than to graft by hand
What are the steps in the healing of a graft union?
- Callus production
- Intermingling of parenchyma cells
- Development of new vascular cambium
- Production of new xylem and phloem
Callus is produced from young tissue closest to the cambium layers
How long does healing a graft union typically take?
Healing usually takes about two weeks and must be completed before the buds on the scion begin to develop leaves.
This is because all the energy is going to go into producing new branches/leaves. Energy needs to go into healing the graft union or the graft will not take
What are some important factors that need to be considered to ensure a successful graft?
Scion needs to be taken from mother plants true to type and disease free, and dormant
Vascular cambium of the scion and rootstock should be in close contact with each other
Scion and rootstock must be held tightly together by wedging, rubber bands, string or tape
Unions can be covered with grafting wax to prevent dehydration and cut surfaces shouldn’t be exposed to dry air
Polarity needs to be observed (buds of the scion need to point upwards)
Temperature needs to be between 10C-30C
What are the limits of grafting?
Scion and rootstock must have some level of botanical relationship or the graft may not be successful
Plant parts from different cultivars of the same species are most likely to graft successfully
What is graft compatibility?
The ability of two different plants, when grafted together, can grow and produce a healthy composite plant
Graft incompatibility is not very well understood and is thought to be related to the production of toxic chemicals.
Sometimes, peach on top of plum won’t work, but plum on top of peach will work. It is what it is.
