Chapter 14 - Principles of grafting and budding

Question 1

What is the difference between budding and grafting?

Answer 1

grafting is the joining two pieces of living plant tissue together so that they will unite, grow and develop as one plant. budding is a form
of grafting. However, the scion is reduced in size
and usually contains only one bud.

Question 2

the scion …

Answer 2

becomes the new shoot system of the

graft. It is composed of a short piece of detached shoot containing several dormant buds,

Question 3

stock or rootstock

Answer 3

is the lower portion of the graft, which develops into the root system of the grafted plant.

Question 4

inter-stock

Answer 4

is a piece of stem inserted by means of two graft unions between the scion and the rootstock. Interstocks are used to avoid incompatibility between the rootstock and scion, to produce special tree forms, to control dis-ease (e.g., fire-blight resistance), or to take advantage of their growth-controlling properties.

Question 5

What are the advantages and disadvantages of seedling vs clonal rootstocks?

Answer 5

roots can be chosen for resistance against disease or and vigour.

Question 6

What is scion rooting? Is it desirable?

Answer 6

it is where the grafted scion has been covered with soil or and planted too deep initiating a rooting response. should e avoided for disease management.

Question 7

Note the 6 reasons for B & G

Answer 7

• Producing desired clones desired that cannot be economically propagated by other means
• Combining different cultivars into a composite plant as scion, rootstock, and inter-stock each part providing a desired characteristic
• Changing cultivars of established plants (top-working),
• Repairing graftage for injuries—including inarching and bridge graftage
• Disease indexing—testing for virus diseases
• Study of plant developmental and physiological processes

Question 8

What benefits can a rootstock have on the scion?

Answer 8

greater plant resistance to biotic and abiotic stress, size control, enhanced reproductive growth, reduction in nursery production time, and increased transplanting success.

Question 9

What are some uses of inter-stocks (double working)? 4

Answer 9

1. The interstock makes it possible to avoid cer-• tain kinds of incompatibility.
2. The interstock may possess disease resistance or cold-hardiness
3. The interstock may reduce vegetative growth and enhance reproductive growth of the tree.
4. Obtaining special forms of plant growth. By grafting certain combinations together it is possible to pro-duce unusual types of plant growth, such as “tree” roses or “weeping”

Question 10

What is top-working?

Answer 10

The grafting of a new cultivar onto established trees in the orchard.

Question 11

How does virus indexing work?

Answer 11

By grafting scions or buds on a plant suspected of carrying the virus onto an indicator plant known to be highly sus-ceptible, and which shows prominent symptoms, virus detection is easily accomplished.

Question 12

What is natural grafting?

Answer 12

branches become naturally grafted together following a long period of being pressed together without disturbance.

Question 13

Note the 3 general steps in graft union formation

Answer 13

1. adhesion of the rootstock and scion,
2. proliferation of callus cells at the graft interface or callus bridge,
3. vascular differentiation across the graft interface

Question 14

Structurally what are some advantages of chip budding compared to T- budding?

Answer 14

when the flaps of bark on either side of the “T” incision on the rootstock are raised, separation occurs from the young xylem.
more rapid and complete union of xylem and cambial tissues of the scion and rootstock after chip budding compared to T-budding.

Question 15

Note the 9 factors that influence grafting success

Answer 15

• Incompatibility
• Plant species and type of graft
• Environmental conditions
• Growth activity of the rootstock
• Polarity
• The craftsmanship of grafting
• Virus contamination, insects, and diseases
• Plant growth regulators and graft union formation
• Post-graftage bud-forcing methods

Question 16

How does temperature influence callusing?

Answer 16

Temperature has a pronounced effect on the production of callus tissue In apple grafts, little, if any, callus is formed below 0°C (32°F) or above 40.

Question 17

Are plant growth regulators routinely used in grafting?

Answer 17

plant growth regulators give variable results in wounding response and graft union formation.

Question 18

In grafting how is high RH maintained around the union area?

Answer 18

With most plants, thorough waxing of the graft union or sealing of the graft union with polyethylene grafting tape, Parafilm, or Buddy Tape helps retain the natural moisture of the tissues, which is all that is necessary.

Question 19

What is meant by bark slipping?

Answer 19

the vascular cambium is actively dividing, producing young thin-walled cells on each side of the cambium. These newly formed cells separate easily from one another, so the bark “slips”

Question 20

In grafting what is bleeding and why does it occur?

Answer 20

A process in which a plant has strong root pressure that causes excess sap flow that can reduce grafting success. incorrect timing or species specific.

Question 21

How can bleeding be reduced?

Answer 21

slanting cuts with graft at higher level.

Question 22

4th step of grafting union…

Answer 22

Wound-Repair Xylem and Phloem: Differentiation of Vascular Cambium Across the Callus Bridge

Question 23

5th step of grafting union…

Answer 23

Production of Secondary Xylem and Phloem from the New Vascular Cambium in the Callus Bridge

Question 24

Why is grafting difficult with monocots?

Answer 24

Monocots have vascular bundles scattered throughout the stem, rather than the continuous vascular cambium of dicots.

Question 25

What are some symptoms of GI? 4

Answer 25

• Failure to form a successful graft or bud union in a high percentage of cases.
  • Yellowing foliage in the latter part of the growing season, followed by early defoliation.
• Marked differences in growth rate or vigor of scion and rootstock.
• clearly indicated by trees breaking off at the point of union.

Question 26

What economic advantages can be realized with dwarfing rootstocks?

Answer 26

intensive plant-ings of small trees resulting from dwarfing rootstock intercept more light and have less internal shading, which is related to greater dry matter production and fruit yield.