Chapter 12 - Cuttings

Question 1

What does ‘adventitious’ mean?

Answer 1

roots and shoots that arise on aerial plant parts, underground stems and old root parts.

Question 2

What is clonal propagation?

Answer 2

The clonal multiplication of plants with propagules of stems, leaves, or roots.

Question 3

What advantage does a stem cutting have over root and leaf cuttings?

Answer 3

requires only that a new adventitious root system be formed, because a potential shoot system (a bud) is already present. apposed to roots who have to produce stem and leaf structures.

Question 4

What is dedifferentiation?

Answer 4

The early stage of adventitious root or bud formation when differentiated cells are triggered to form new meristematic regions, such as a shoot produceing calluse which differentiates into roots.

Question 5

Is there a correlation between the presence of a sclerenchyma ring and the ability of a stem cutting to strike?

Answer 5

yes, sclerenchyma rings have less chance to striking such as in olives.

Question 6

What is callus?

Answer 6

a layer of parenchyma cells formed in response to wounding. wound periderm. callus can differentiate into any cell type of the organism.

Question 7

Leaf and root cuttings need to form both __________ and _______ meristems?

Answer 7

shoot root

Question 8

Wound periderm

Answer 8

A mass of callus cells that forms a protective layer behind the wounded surface of a cutting.

Question 9

lignin

Answer 9

An abundant plant polymer in cell walls that provides structural support and mechanical barriers for pest resistance.

Question 10

What is polarity?

Answer 10

Root cuttings of many species form roots at the distal end and shoots at the proximal end. Changing the position of a stem cutting with respect to gravity does not alter this tendency

Question 11

What effect does gravity have on polarity?

Answer 11

gravity does not alter polarity.

Question 12

What is the physiological basis of polarity?

Answer 12

Auxins are drawn to the location of a cut or wound through active transport mechanisms.

Question 13

What effect do buds have on the rooting of stem cuttings? Why?

Answer 13

sprouting buds promoted root initiation just below the buds in cuttings of such plants as willow, poplar, currant, and grape.
buds produce a chemical pushing root growth.

Question 14

What effect do leaves have on the rooting of stem cuttings?

Answer 14

the presence of leaves on cuttings exerts a strong stimulating influence on rooting. leaves produce auxins, basipetal transport of auxins promote rooting.

Question 15

What 2 auxins are mostly used for rooting cuttings?

Answer 15

1. indole-3-butyric acid (IBA)

2. a-naphthalene acetic acid (NAA)

Question 16

What effect do cytokinins have on rooting cuttings?

Answer 16

Inhibits; and high auxin: low cytokinin ratio promotes rooting

Question 17

What effect do GAs have on rooting cuttings?

Answer 17

Inhibit root formation

Question 18

What effect do ethylene have on rooting cuttings?

Answer 18

Can promote with auxin-induced rooting of some herbaceous plants

Question 19

What effect do ABA have on rooting cuttings?

Answer 19

Inhibit root formation

Question 20

How does rejuvenation relate to cuttings propagation?

Answer 20

juvenile wood is largely more successful at rooting than old wood. induced rejuvenation allows access to this juvenile wood for cuttings.

Question 21

recalcitrant plants

Answer 21

Plants that are difficult to root from cuttings. They lack a rooting morphogen(s) and/or lack the cell sensitivity to respond to the morphogen(s), even though natural auxin may or may not be present in abundance.

Question 22

In plant propagation what is stooling?

Answer 22

for multi stemmed suckering shrubs and trees. piling soil on top of stems of suckering trees initiating rooting, the following season this is cutoff as a new plant.

Question 23

propagation enigma’

Answer 23

In difficult-to-root woody plant species, the ease of adventitious root formation declines with the age of parent stock, resulting in a propagation enigma

Question 24

What are some techniques for inducing rejuvenation?

Answer 24

1. Forcing epicormic sprouts
2. removing terminal and lateral buds and spraying stock plants of Pinus sylvestris with a mixture of cytokinin, triiodobenzoic acid, and Alar (daminozide)
3. Chemical manipulation with gibberellin sprays
4. by forcing juvenile growth from sphaeroblasts, wartlike protuberances containing meristematic and conductive tissues

Question 25

for good cuttings how should stock plants be manipulated in terms of: water status , temp,

Answer 25

advantages of periodic, controlled drought stress, extreme drought stress is not desirable. Reducing irradiance levels of stock plants can sometimes enhance rooting of difficult-to-root species.

Question 26

for good cuttings how should stock plants be manipulated in terms of: carbohydrates, C:N ratio

Answer 26

The relationship between carbohydrates and adventitious root formation remains controversial. Rooting can be enhanced by controlling nitro-gen fertility of stock plants such that cutting shoot development is not stimulated by high N levels. high carbohydrate/low-to-moderate nitrogen ratio is optimal for rooting dor-mant hardwood cuttings.

Question 27

Generally, which is better: cuttings from terminal or lateral shoots?

Answer 27

for deciduous woody plants: lateral shoots, slower growing higher carbohydrate to nitrogen level. although No one type of cutting material is best for all plants. possibility of lateral shoot cutting becoming plagiotropic

Question 28

plagiotropic

Answer 28

A horizontal branchlike growth habit that is generally not

horticulturally desirable.

Question 29

orthotropic

Answer 29

A desirable, upright growth allowing production of symmetrical plants.

Question 30

Generally, which is better: basal or terminal sections of a long shoot?

Answer 30

highest rooting, in many cases, found in cuttings taken from the basal portions of the shoot.

Question 31

if unrooted cuttings (URCs) must be stored what are the best conditions?

Answer 31

depends on storage conditions, state of the cuttings, and species. It is important that dry matter losses and pathogens be minimized. Within the storage unit, it is best to maintain nearly 100 percent humidity, and the temperature should be as low as the hardiness of the plant tolerance.

Question 32

what auxins are most commonly used in cuttings propagation?

Answer 32

Mixtures of root-promoting substances are sometimes more effective than either component alone.

Question 33

auxin treatment of URCs can promote root initiation, but inhibit ___________?

Answer 33

bud break

Question 34

of IBA and IAA which can be stored for longer? Why?

Answer 34

IBA can be stored longer in alcohol solutions.

Question 35

what is a nutritional problem with misting? how can this effect be alleviated/minimised?

Answer 35

mist can severely leach cuttings of nutrients. High leaching rates are avoided by reducing the
misting frequency and using mist nozzles that supply smaller volumes of water

Question 36

list several reasons why wounding the base of a cutting can be advantageous.

Answer 36

• Wounded tissues are stimulated into cell division and production of root primordia
• callus production and root development frequently are heavier along the margins of the wound.
• Potentially, cells at the base of the cutting influenced by wounding have enhanced receptivity to respond to auxin and other morphogens (nonauxin endogenous compounds) essen-tial to rooting
• Wounding cuttings may also permit greater absorption of applied growth regulators by the tissues at the base of the cuttings.

Question 37

in an unstruck stem cutting does most moisture enter by the leaves or by the base of the cutting?

Answer 37

the cutting base

Question 38

misting should occur more frequently if the VPD between the cutting and the air is _____________?

Answer 38

high

Question 39

what techniques can be used to reduce VPD for cuttings? 3

Answer 39

1. intermittent mist
2. non-misted enclosures
3. fogging systems

Question 40

what advantages/disadvantages does fogging have compared to misting?

Answer 40

water does not condense on the surfaces of the cutting. avoid foliar leaching and oversaturation of media..

Question 41

misting tends to cool media how is this overcome?

Answer 41

by heating at the propagation bench level

Question 42

usually it is better if air temperature is ____than the media temperature?

Answer 42

lower

Question 43

how do light intensity, photoperiod and wavelength influence cuttings propagation?

Answer 43

When light levels are too high, cuttings experience stress and wilt. long days or continuous illumination are generally more effective than short days

Question 44

can cuttings strike if they aren’t photosynthesising?

Answer 44

Photosynthesis by cut-tings is not an absolute requirement for root formation, Increasing light irradi-ance has not always promoted rooting,

Question 45

can cuttings strike if they aren’t photosynthesising?

Answer 45

Photosynthesis by cut-tings is not an absolute requirement for root formation, Increasing light irradiance has not always promoted rooting,