Lecture 18: Grafts and Wounds Flashcards
What is grafting?
A set of techniques for joining together 2+ plant parts from different plants so they grow as 1 (makes a chimera)
What is a chimera?
2 different plant genotypes are growing together in the same plant
An example of a chimera?
The roots of an apple tree in a commercial orchard came from a plant with a disease resistant and dwarfing genotype while the shoot has a genotype exhibiting great tasting apples.
What is a scion?
Genotype intended for the above-ground part of the plant
What is a rootstock?
Genotype intended for the below ground bit of the plant
What is budding?
Grafting technique where the scion is a bud with the genotype intended for the above ground part
7 reasons why a horticulturist would graft (as many as you can)
1) Create unique, commercially desirable ornamentals
2) Perpetuate desirable genotypes of plants that are notoriously tough to root
3) Change varieties or cultivars
4) Produce trees with specialized forms (like weeping habit)
5) Increase growth rate of seedlings
6) Repair damaged palnts
7) Take advantage of rootstock characteristics (like dwarfing)
Examples of plants that have difficulty rooting:
Japanese Maple, conifer
Why would someone want to change varieties or cultivars?
Apple tree’s apples are no longer commercially desirable. (More time and cost efficient than digging up and replanting)
2 reasons against grafting
1) Requires experience in technique
2) Must need a good reason to graft and no easier or cheaper way to do it.
2 things that happen when you do a stem cutting:
1) sells along cut a sliced open, die, and become necrotic tissue
2) surviving cells (typically parenchyma) one layer in from the cut respond to the wound
2 cell responses to the wound:
1) cells rapidly exclude compounds like suberin to protect plant from excess water loss and invasion by disease or insects (takes hour)
2) cells are stimulated to divide and produce a mass of new cells to cover and protect wound- called callus (takes years)
What cells does the callus originate from?
Parenchyma cells in pith, phloem, or xylem regions(depends of species) in both scion and rootstock
What is a callus bridge
Callus from rootstock and scion grow together
What makes cell differentiation quicker in a graft?
Close alignment of cambium in scion and rootstock