Exam 2 Part 2 Grafting

Question 1

Grafting

Answer 1

the art and science of connecting two or more pieces of living plant tissue together in such a manner that they will unite and subsequently grow and develop as one plant.

Question 2

scion

Answer 2

the short piece of detached shoot containing several dormant buds, which, when united with the stock, comprises the upper portion of the graft and from which will grow the stem and branches of the grafted plant.

Question 3

stock

Answer 3

the lower portion of the graft which develops into the root system of the grafted plant. It may be a seedling, a rooted cutting, a layered plant, or a mature tree

Question 4

budding

Answer 4

a type of grafting, except that the scion is reduced in size to consist of a vegetative bud

Question 5

interstock

Answer 5

a piece of stem inserted by means of two graft unions between the scion and the rootstock.

Question 6

graft union

Answer 6

the juncture at which the scion and stock of a grafted plant have successfully united.

Question 7

double working

Answer 7

double graft involving a rootstock, interstock, and scion whether done in one or two steps

Question 8

incompatibility

Answer 8

the inability of a grafted scion and stock to produce a successful graft union or to have the resulting grafted plant develop unsatisfactorily

Question 9

vascular cambium

Answer 9

a thin tissue of the plant located between the bark (phloem) and the wood (xylem)

Question 10

callus

Answer 10

mass of parenchyma cells that develop from and around wounded plant tissue. It occurs at the junction of a graft union arising from the living cells of both scion and stock

Question 11

reasons for grafting

Answer 11

LPerpetuate clones that can’t be conveniently propagated by other asexual methods –many fruit and nut species –some woody ornamentals –cutting propagation impractical for many plants

Question 12

reasons for grafting

Answer 12

LObtain benefits of certain rootstocks – Stress tolerance – Pest resistance – Size control LApple (East Malling Research Station) L‘Malling 27’: 4-6 ft tall L‘MM111’: Semi-dwarf, disease resistant, and propagates well

Question 13

2 types of rootstocks

Answer 13

seedling

clonal

Question 14

advantages of seedling rootstocks

Answer 14

LSimple and economical to produce LViruses usually not seed transmitted LSometimes, better developed root system as compared to cuttings or clonal rootstocks

Question 15

disadvantages of seedling rootstocks

Answer 15

LGenetic variation among seedlings LReduce this variability by: –careful selection of seed source –protection from cross pollination –grading nursery trees at digging –discarding off types before grafting

Question 16

clonal rootstocks

Answer 16

LPropagated by mound layering or rooted cuttings

Question 17

advantages of clonal rootstocks

Answer 17

LUniformity LPreserves special characteristics and specific influences –growth (dwarfing, invigorating) –flowering (precocity) –disease resistance –soil adaptation

Question 18

disadvantages of clonal rootstocks

Answer 18

LPotential for transmission of systemic pathogens to ‘clean’ scions LExpense

Question 19

whip or splice graft

Answer 19

LGenerally done in late winter when both stock and scion are dormant

Question 20

whip and tongue

Answer 20

LGenerally done in late winter when both stock and scion are dormant

Question 21

topworking

Answer 21

Changing the scion cultivar by grafting onto established plantings or rootstocks

Question 22

graft incompatibility

Answer 22

Inability of parts of 2 or more different plants to form a successful graft union or grow satisfactorily after grafting

Question 23

localized incompatibility

Answer 23

LUsually overcome by insertion of a mutually compatible rootstock LMust be physical contact between the two grafting partners

Question 24

translocated incompatibility

Answer 24

LNot usually overcome by insertion of mutually compatible interstem LA biochemical signal that is translocated across the graft union causes the failure LVirus induced failure can be included here

Question 25

causes and machanisms of incompatibility

Answer 25

1.Physiological and Biochemical –Chemicals that inhibit normal graft healing 2.Modification of Cells and Tissues –Tissues fail to properly develop through the callus bridge 3.Cell Recognition of the Grafting Partners –Some type of communication between the cells of the two partners (Pollen/Stigma)

Question 26

correcting incompatibility

Answer 26

LOnly localized incompatibility can be corrected –Interstock –Inarching