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This is to certify that the

thesis entitled

THE PROPAGATION AND OVERWINTER SURVIVAL OF
Viburnum carlesii (KOREAN SPICE VIBURNUM)
SOFTWOOD CUTTINCS

presented by

 

Timothy Duncan Wood

has been accepted towards fulfillment
of the requirements for

 

 

Master ' 3 degree in Horticulture

 

, /
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Major professor

Date 6/01 i/ 7?

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THE PROPAGATION AND OVERWINTER SURVIVAL OF

Viburnum cariesii (KOREAN SPICE VIBURNUM) SOFTWOOD CUTTINGS

BY

Timothy Duncan Wood

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Horticulture

1990

",4 '7- 7
A7” 73

ABSTRACT

THE PROPAGATION AND OVERWINTER SURVIVAL OF
Viburnum carlesii (KOREAN SPICE VIBURNUM) SOFTWOOD CUTTINGS

BY
Timothy D. Wood

Experiments were conducted to investigate the overwinter
survival of Viburnum carlesii propagated from softwood material.

The growth and development of stock plants and cuttings were
characterized. Lateral bud elongation was influenced by node
location. Auxin did not improve percent rooting but improved
rooting quality. Sixteen hours of high intensity lighting
induced the greatest percentage of budbreak (97% at day 55),
but did not improve overwinter survival. Eight hours of
supplemental light plus a night break increased the number of
cuttings that broke bud (68% at day 55) and increased the
overwinter survival of subterminal cuttings. Eight hours
supplemental HID light did not increase budbreak.but improved
the overwinter survival of subterminal cuttings. Survival
ranged between 82% and 100% for subterminal cuttings under 8
hours of supplemental light if they had broken bud prior to

overwintering.

To Tracy Lynn Wood

Whose patience, support and love gave me the strength
to quit my job, move, go back to school and spend many long,
sleepless nights away from her and our beautiful daughter

Jenny.

iii

ACKNOWLEDGMENT

I would like to thank Dr. Arthur C. Cameron, my major
professor, for his guidance, support, insight and friendship.
I would also like to thank Dr. Robert Schutzki and Dr. Gerard
Donnelly for help and guidance with my research and program.

I would like to specifically thank my parents David and
Arlene Wood for making it all possible.

Special thanks to Ralph Shugert and Zelenka Nursery for
providing encouragement and plant material. I would like to
thank all of the people who assisted me over the last two
years with both physical and moral support. Last, but not

least, Thank you Lord, I could.not have done it without you.

iv

TABLE OF CONTENTS

page
LIST OF TABLES O O O O O O O O O O O O O O O O O O O 0 Vi

LIST OF FIGURES O O O O O O O O I O O O O O O O O O O Viii

CHAPTER I: CHARACTERIZATION AND ANALYSIS OF STEM

AND BUD GROWTH IN Viburnum cariesii . . . . . . . . 1
Abstract . . . . . . . . . . . . . . . . . . . . 2
Introduction . . . . . . . . . . . . . . . . . . 3
Botanical Description. . . . . . . . . . . . . . 4
Materials and Methods. . . . . . . . . . . . . . 5
Results and Discussion . . . . . . . . . . . . . 6
List of References . . . . . . . . . . . . . . . 14
CHAPTER II: THE EFFECT OF AUXIN CONCENTRATION AND
CUTTING TYPE ON THE ROOTING OF Viburnum carlesii . . 15
Abstract. . . . . . . . . . . . . . . . . . . . 16
Introduction. . . . . . . . . . . . . . . . . . 17
Materials and Methods . . . . . . . . . . . . . 18
Results and Discussion. . . . . . . . . . . . . 20
List of References. . . . . . . . . . . . . . . 27
CHAPTER III: THE EFFECT OF SUPPLEMENTAL LIGHTING
AND PHOTOPERIOD ON TERMINAL AND SUBTERMINAL
Viburnum carlesii ROOTED CUTTINGS AND
SUBSEQUENT OVERWINTER SURVIVAL. . . . . . . . . 28
Abstract. . . . . . . . . . . . . . . . . . . . 29
Introduction. . . . . . . . . . . . . . . . . . 30
Materials and Methods . . . . . . . . . . . . . 42
Results . . . . . . . . . . . . . . . . . . . . 45
Discussion. . . . . . . . . . . . . . . . . . . 49
List of References. . . . . . . . . . . . . . . 67

LIST OF TABLES

Table Page
CHAPTER II

2.1. Auxin concentrations applied in parts per
million 2-propanol solvent . . . . . . . . . . . 22

2.2. Analysis of variance for percent rooting of

Viburnum carlesii as influenced by cutting
type and auxin concentration . . . . . . . . . . 23

2.3. Analysis of variance for root quality rating

of Viburnum carlesii as influenced by cutting
type and auxin concentration . . . . . . . . . . 23

2.4. The effect of auxin concentration on percent
rooting and rooting quality of Viburnum
cwleSii O O O I O O O O O I O O O O O O I O O O O O 24

CHAPTER III

3.1. Taxa reported to be difficult to overwinter
as rooted cuttings . . . . . . . . . . . . . . . 55

3.2. Budbreaks of Viburnum cariesii induced by
light treatments averaged over cutting type.
Budbreak averaged over cutting type. Chi-square
contingency table comparisons at days 20,
30, 40 and 55. n=100 . . . . . . . . . . . . . . 56

3.3. Analysis of variance for stem growth of'MDunmmr
anumfi at one week after budbreak . . . . . . . . 57

3.4. Budbreak of Viburnum cariesii at one week
after 75 days of storage at 0°C.
Chi-square contingency table comparisons . . . . 58

3.5. Survival of Viburnum cariesii at two weeks
after 75 days of storage at 0°C. Chi-square
contingency table comparisons. . . . . . . . . . 58

vi

Table

Percent survival of cuttings of Viburnum carlesii
after 75 days storage as a function of light
treatment and cutting type with regard to the
presence or abscence of growth prior to storage
Relavent chi-square contingency table comparisons
presented at the bottom of the table. . . . . .

vii

Page

59

LIST OF FIGURES

CHAPTER I

Bud and internode growth of stock plant stems

and bench cuttings in Viburnum cariesii. A.
Average bud size and the number of budbreaks
and B. internode growth, at two node locations
(first and second nodes laid down) on

Viburnum carlesii stems and on 2 to 3 node
cuttings stuck on June 1, 1989 in a greenhouse
mist benCho O O O O O O O I O O O I O O O O O 0

Growth and development of Viburnum cariesii

stems, stripped of leaves and not stripped.

A. Stem elongation B. NOde number. Leaves were
stripped June 1, 1989. . . . . . . . . . . . . .

Average number of lateral budbreaks at four
node locations (node 1 being the first laid
down and so on) on A. unstripped and B. stripped

Viburnum carlarii' stems. Leaves were stripped
June 1’ 1989 O O O O O O O I O O O O O O O I O O

The appearance of successive nodes and

the average internode length on Viburnum carlesii
stems on field grown stock-plants in A. 1989.
B. 1990 O O O O O O O O O O I O O O O O O O O 0

CHAPTER II

Cutting types (terminal and subterminal) used in

rooting Viburnum carlesii'. Leaves are not shown
for better visibility of the nodes . . . . . . .

Rating scale from 1-5 after 12 weeks for Viburnum
CWii rOOt ing qua 1 ity O O O O O I 0 O O O O O 0

viii

Page

10

11

12

13

25

26

CHAPTER III

Figure

3.1.

3.2.

Cumulative budbreak response of terminal and

subterminal rooted of Viburnum carlesii cuttings
under four-55 day light treatments. Chi-square
contingency table comparisons between terminal
and subterminal cuttings (located at the bottom
of each graph) with a tabular chi-square value
of 3.84, 1 degree of freedom and * .05 prob . .

Cumulative plant budbreak response of terminal
and subterminal rooted cuttings of Viburnum

anhnfi averaged over four different 55 day

light treatments. Chi-square contingency table
comparisons between terminal and subterminal
cuttings (located at the bottom of graph)

with a tabular chi square value of 3.84,

1 degree of freedom and .05 prob . . . . . . . .

Cummulative plant budbreak response of rooted

cuttings of Viburnum cariesii under four
different 55-day light treatments averaged
over terminal and subterminal cutting types . .

Mean stem growth per plant Viburnum cariesii

1 week after induced budbreak under four
different 55 day light treatments and averaged
over terminal and subterminal cutting type . . .

Mean stem growth of Viburnum carlesii terminal

and subterminal cuttings (per plant 1 week after
budbreak and averaged over four different 55 day
light treatments) . . . . . . . . . . . . . . .

Percent budbreak and survival of terminal and

subterminal cuttings of Viburnum cariesii' that
had been treated with four different 55 day light
treatments and stored for 75 days at 0%: . . . .

ix

Page

60

62

63

64

65

66

CHAPTER I

CHARACTERIZATION AND ANALYSIS OF STEM

AND BUD GROWTH IN Viburnum cariesii'

Abstract. The formation and growth of Viburnum carlesii'

internodes and buds were analyzed on stock plant stems and
cuttings defoliated and intact. Cuttings showed no visible
signs of bud or internode growth. Defoliated cuttings died
within two weeks. Stock plant buds and internodes showed
continued growth and elongation. Stripping leaves off stock
plant stems reduced average stem growth but had no influence
on the number of nodes produced when compared to unstripped
stems. The stripping of stock plant stems increased lateral
budbreak compared to unstripped stems. ‘Unstripped plants had
relatively fewer laterals break bud. The lateral buds on the
second and third nodes had the greatest tendency for lateral
budbreak in both stripped and unstripped stems. Buds at the
first node did not break unless the leaves were stripped.
Extreme variations were found in node formation and internode
expansion between two successive years. The relationship
between growth patterns and the variability in rooting and

overwinter survival is discussed.

3
Introduction. In Michigan, softwood cuttings of Viburnum cariesii

Hemsl. are commonly collected between the first of June and
the end.of.July, after the first flush.of'growth.has hardened.
One grower (Schaefer, 1985) recommends taking cuttings when
the stems snap easily when bent. Dirr and Heuser, (1987)
claimed that the timing of cutting propagation will probably
continue to be based on trial and error because scientific
methods are unable to analyze plant material to determine the
time of its physiological disposition for rooting.

The stage of plant growth might offer a better indicator
for the proper timing of cutting propagation. Aspects of
plant growth and development are dictated by environmental
conditions which trigger internal physiological and
biochemical processes. Therefore the stages of plant growth
and development may represent external signs that indicate
internal physiological conditions. The of pattern of plant
growth and development has the potential of providing an
effective indicator for the proper timing of propagation.

The time of collection may also influence the success of

overwintering Viburnum cariesi'i cuttings. Smalley and Dirr (1887)

found that Acer rubrum 'October Glory' rooted cuttings survived
at higher rates (93%) if taken in mid-August compared to
cuttings taken in mid-June (81%). The maturity of the lateral
buds may be a factor in their ability to break in spring.

The purpose of this experiment was to examine and

characterize the growth and development of Vibumum cariesii and

4
to determine its relation to propagation and overwintering

success.
Botanical description Viburnum cariesii, a Korean member of the

Caprifoliaceae family, is a medium sized (1-2 meters)
deciduous shrub. Its leaves are simple, ovate-elliptical,
rounded at the base and are 4 to 8 cm long and 3 to 5 cm wide.
The leaves are1a dull green above and.pale below in the summer
and turn a burgundy-red in the fall. The leaf is irregularly
toothed and has stellate pubescence on each side. Its
phyllotaxy is characterized as opposite and decussate with
each succeeding set of leaves (or buds) being at right angles
when compared head on to an adjacent leaf pair (Donahue,
1981) . The buds are naked, having no scales for winter
protection. Its stems are light green with stellate
pubescence when young. As the stem ages it turns a light
grey-brown, looses its pubescence and.develops numerous small
longitudinal fissures (Dirr, 1983). The inflorescence is a
terminal, stalked, semi-globose cyme (5-8 cm across) and its
many salverform flowers are fertile, fragrant and are a
'whitish-pink color (Bailey, 1949). The flower buds are formed
in summer, overwinter as well- developed, compact, naked buds,
and bloom in late April or May (Donahue, 1980).

Shoot growth from year to year can either be monopodial
or sympodial (Donahue, 1980). If a flower bud is formed, no
terminal vegetative bud will be formed and the main axis will
be replaced by a either a lateral bud or branch (sympodial

5
growth) . Shoot growth can continue to be monopodial, with one
continuous main axis for several years until a terminal flower

bud is formed.
Materials and Methods. On June 1, 1989 in East Lansing,

Michigan, 20 stems were tagged randomly on three field plants.
The Plants were approximately 10 years old. During the
growing season the plants were watered as necessary and the
soil was cultivated. Ten of the stems were continually
stripped of their leaves. 0n the same day 40 two node
(approximately 10-12 cm) stem cuttings were stuck in a
greenhouse mist-bench for rooting. The cuttings were treated
with a five second basal quickdip of Wood's Rooting Compound
(1.03% IBA / 0.51% NAA). They were inserted into 10 cm of
coarse perlite and misted for 3 seconds every 10 minutes from
0800 to 2000 HR. Bottom heat was maintained at 25°C with
mylar heat strips (Agritape, Ken-Bar Inc., Reading, MA.) .
Cuttings were shaded with black polyethylene side curtains and
55 percent shade cloth. The greenhouse temperature was set
at 25°C/21°C day/night. Twenty of the cuttings were stripped
of all leaves.

The appearance of axillary buds and internodes were
noted and their lengths were measured at least every two weeks
from June 10, 1989 until September 8, 1989. Bud length was
measured from the point of connection on the stem to the tip
of the bud. Because the buds have no scales, budbreak was

defined as the point when the upper surface of the leaf first

6
became visible. Growth analysis of field plants was repeated
in 1990 from April 16 until July 3, 1990 using 20 tagged stems

(no cuttings or stripped stems used).
Results and discussion. No visible change in bud length

occurred on the cuttings in the mist bench (Figure 1.1) .
Stock plants buds continued to elongate until leaf unfolding
occurred. Comparing mean internode length between the two
type of stems revealed a similar trend. The cutting
internodes did not expand in length, while the stock plant
internodes continued to increase in length until June 16.
The act of taking a cutting (removal from the stock plant)
appears to result in the total cessation of bud and stem
elongation. ‘

Stripping a plant of its leaves has been shown to induce

lateral budbreaks depending on the time of the year it is done
(Fuchigami etaL, 1977) . The stripping of leaves off cuttings

has been suggested as a production method to force growth
while rooting (Smalley and Dirr, 1986) . Forcing growth prior
to winter on rooted softwood cuttings has been shown to
improve the overwinter survival of some species (Smalley and

Dirr, 1987). Also, if lateral buds can be forced it gives an
indication of bud maturity (Fuchigami et at). In our experiment

all cuttings died in a matter of weeks if the leaves were
stripped (data not shown). Leaves are apparently required for
a softwood cutting to remain alive until roots can be formed.

If leaf removal is used on unrooted cuttings, as a technique

7
to force growth, some leaves should be retained.

If the leaves were removed from the stems on stock
plants, mean stem growth was reduced compared to the mean
growth of stems not stripped of their leaves (Figure 1.2).
Interestingly, the removal of leaves from a stem did not
reduce the total number of nodes produced by that stem. Both
stripped and unstripped stems produced an average of about
three nodes by September 8, 1989. This might indicate that
all of the nodes were preformed before the June 1 stripping
date.

Lateral budbreak was monitored at each node location.
Nodes were numbered in the same sequence as they appeared
(for example, node 1 appeared first and then node 2 appeared
next above node 1). None of the buds at the first node broke
on unstripped stems (Figure 1.3). The second node had 25%
budbreak and the third node had 40% budbreak by July 14.
Only 19% of the lateral buds broke on unstripped stems. This

is expected considering the normal, limited branching of
Viburnum cariesii'. Overall lateral budbreak increased (36%) when

stems were stripped of leaves. The first node had budbreaks
when the leaves were stripped. Stripping induced a greater
amount of budbreaks especially at the second node (70%)
location.

Stripped of leaves or intact, different nodes appear to
have different lateral bud breaking ability. This may have

practical applications for increasing the overwinter survival

8
of Viburnum carlesii cuttings. When selecting cuttings it may be

an advantage to place the node with the best chance of
budbreak above the propagation medium. For example, if two
2-node cuttings were taken from a stem containing 4 nodes, the
fourth node would be above the propagation medium on the
terminal cuttings and the second node would be above the
medium on the subterminal cutting. If eventual budbreak
followed the same trend as our data from the stripping
experiment, the terminal cutting would have only a 5% chance
of budbreak and the subterminal cutting would have a 30%
chance of budbreak. If a subterminal cutting is released of
apical dominance (as were the stripped stems) it would have
a 70% chance of budbreak. This does not take into account
other environmental factors which might influence budbreak
(eg. light, See Chapter 3).

The difference in bud breaking ability between different
node locations could be explained by the natural growth
pattern of the stem. The growth of each internode levels off
as the next node begins to expand (Figure 1.4). The new node
is probably a stronger sink for carbohydrates and has apical
dominance over the older node. The formation of a new node
may influence the overall development of the buds below that
node. If this were true, the manipulation of stock plant
growth could be used to increase the time between node
appearance, and perhaps the breaking ability of the buds.

Also in question is the total length of time necessary

9

for a stem to reach full maturity. Stem developmental
patterns (Figure 1.4), reveal that internode 2 did not reach
its maximum length until August 11. Year to year differences
are found in the pattern of mean internode extension. In
1990, internode 2 reached it maximum on June 5, more than two
months sooner than in 1989. This clearly demonstrates the
variability in plant growth and development from year to year.
If cuttings were taken in mid-June each year two different
types of stem material would have been used. This may help
explain why rooting and overwinter survival can vary so much
from year to year even when the same stock plants are used and
when cuttings are collected on the same date.

Plant propagation researchers should further examine the
growth and development patterns of stock plants. An attempt
should be made to link specific stages of plant development
with the rooting and overwinter survival of cuttings. For
cutting propagation to be reliable, the timing of propagation
must be based on indicators representative of the
physiological status of the plant. The timing of cutting
propagation based on a calendar date inherently creates

variability from year-to-year.

10

 

BUD GROWTH A

A 14- H BENCH—CUTTING n=4o 1
E o—o FIELD—STOCK PLANT

12-
E 73': BUDBREAKS 1
I 10"1 _
'—
(D
Z 8— '-
LLJ 5
._|

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C3 4 ‘
D 73'
co 4- -
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> 2.4 .—_.___.——-—.-——-——.————.————. -1
<

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6—1 6:9 Y 6316 T 532? 6—30 Y 7:6 ' 7—'14
DATE OF OBSERVATIONS

 

 

 

 

 

 

B
INTERNODE GROWTH
100
’g‘ 901 4—4 BENCH—CUTHNG "=40 _
E o—o FIELD—STOCK PLANT
v 80- A A A —.
u] «////pflflfl'w v v
1:] 70“ —
(f) —.
LL] 60-1
Q 504 _
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E 40— __A 1
E 30a Rf. - - «
z
— mp -
0' 10— -
i c) . . i. I. . .
6—1 5116 6153 6:50 716 7—H4
DATE OF OBSERVATIONS
Figure 1.1. Bud and internode growth of stock plant stems

and bench cuttings in Viburnum cariesii. A. Average bud
length and the number of budbreaks and B. internode
growth, at two node locations (first and second nodes

laid down) on Vi'bumum cariesii stems and on 2 to 3 node
cuttings stuck on June 1, 1989 in a greenhouse mist
bench.

 

 

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Growth and development of Viburnum carlesu stems,
stripped of leaves and not stripped. A. Stem elongation

DATE OF OBSERVATIONS
B. Node number. Leaves were stripped June 1, 1989.

Figure 1. 2 .

12

NOT STRIPPED A

 

100
_‘ E NODE 1
~ :1 NODE 2
801 - NODE 3
70 @ NODE 4

405
30;
20:
10.3
OO ‘

6/16 6/30 7/14 *7/28 3/11 8/24 79/8

DATE OF OBSERVATION

A l L l A 1 14 1

PERCENT BUDBREAK
0'
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114111

 

 

  

STRIPPED B

 

100
90; g NOOE 1 _

~ 1: NODE 2 «
801 - NODE :5 ‘

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40-

 

 

 

 

30-1

PERCENT BUDBREAK

20~
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8 8

6/16 6/30 7/14 7/28 /11

DATE OF OBSERVATION

Figure 1.3. Average number of lateral budbreaks at four
node locations (node 1 being the first laid down and so

on) on A. unstripped and B. stripped Viburnum cariesii stems.
Leaves were stripped June 1, 1989.

13

 

 

 

 

 

     

 

 

 

1 989
100
H INTERNODE 1
90- H INTERNODE 2 ‘
80_ a—a INTERNOOE 3 1
A 0—0 INTERNODE 4
E 7Qu I
E
V 50— —
I
S 50~ -1
E
_, 40~ -1
o
> 30— a
<
204 ~
10- ~
0 ' r Y i - 6' i r W
6-16 6-30 7-14 7—28 8-11 8—25 9-8
DATE OF OBSERVATIONS
100
0—0 INTERNODE 1
90- 13—6 INTERNODE 2 ‘
80_ A—A 111151211005 3 1
A H INTERNODE 4
E 704 v—v PEDUNCLE ~
V 60~ a
I
5 50— a
E .
_J 404 -1
O
> 30— ~
<
204 -
10.4 _
4—1Es 4:23— 53V 5122' 6Y—5 - 67-19' 71-3 . 1
DATE OF OBSERVATIONS
Figure 1.4. The appearance of successive nodes and the

average internode length on Viburnum carlesii stems on field
grown stock-plants in A. 1989. B. 1990.

LIST OF REFERENCES

LIST OF REFERENCES

Bailey, L.H. 1949. Manual of cultivated plants. Revised Ed.
New York: Macmillan. pp. 1290.

Dirr, M.A. 1983. Manual of woody landscape plants: Their
identification, ornamental characteristics, culture,
propagation and uses. Champaign: Stipes. pp. 826.

Dirr M.A. and C.W. Heuser. 1987. The reference manual of woody
plant propagation: From seed to tissue culture. Athens:
Varsity Press. pp. 239.

Donahue, M. 1981. Growth. patterns in.'woody' plants ‘with
examples from the genus Viburnum. Arnoldia 41:1-13.

Donahue, M. 1980. Flowering times in Viburnum. Arnoldia 40:2-
22.

Fuchigami L.H., M. Hotze and C.J. Weiser. 1977. The
relationship of vegetative maturity to rest development
and spring bud-break. J. Amer. Soc. Hort. Sci.
102(4):450-452.

Smalley, T.J. and M.A. Dirr. 1986. The overwinter survival of
problems of rooted cuttings. The Plant Propagator.
32(3):1o-14.

Smalley, T.J. and M.A. Dirr. 1987. The effect of extended
photoperiod on budbreak, overwinter survival, and

carbohydrate levels of.Aaflvubnun 'October Glory' rooted
cuttings. J. Amer. Soc. Hort. Sci. 112(3):459-463.

14

CHAPTER II

THE EFFECT OF AUXIN CONCENTRATION AND CUTTING

TYPE ON THE ROOTING OF Viburnum carlesii

15

ABSTRACT

Percent rooting and root quality of Viburnum cariesii softwood

cuttings were measured and analyzed at six different
concentrations of auxin, each comprised of Indole-B-butyric
acid (IBA) to fi-Napthleneacetic acid (NAA) mixed at a 2:1
ratio. Cuttings were collected July 7, 1989. The effect of
cutting type, either two node terminal or subterminal, was
also investigated. Cutting type had no affect on percent
rooting or root quality. No significant difference in percent
rooting was found between the levels of auxin concentration.
Overall rooting was 84%. Rooting quality was slightly higher
when auxin was used as compared to the control but decreased

at the highest concentration of applied auxin.

16

17

Introduction. Viburnum cariesii Hemsl. (Korean Spice Viburnum)
is commonly propagated by softwood cuttings because of the
variability associated with seed and a suckering problem
encountered with grafted plants (Dirr and Heuser, 1987) .
Researchers and growers have reported different degrees of
rooting success and serious production problems when
propagating from softwood cuttings (Dirr and Heuser, 1987:
McMillan Browse, 1970: Miller and Smeal, 1972: Schaefer,

1985).

Dirr and Heuser (1987) reported 80% rooting of Viburnum

carlesii in peat:perlite before mid-July when treated with 8000

ppm Indole-B-butyric acid (IBA) talc. Schaefer (1985)
recommends 2,500 ppm IBA but gives no rooting data. Miller

and Smeal (1972) tested seven different commercial rooting
substances on Viburnum carlesii stuck June 16, 1970. Rooting

percentages ranged from 8% (Hormodin #3, 8,000 ppm IBA in
talc) to 60% (Jiffy Grow #2, hormone composition unknown) and
30% rooting for the control. In the same study, rooting
quality was rated on scale of 1 to 5, with 1 equaling light
rooting and 5 representing very heavy rooting. Out of a
possible 250 total points, Hormodin #3 received the lowest
rating (7 points) and Jiffy Grow #2 was highest with a rating
(66 points). The control received 21 points. Some

researchers have suggested that more research is needed to

find the optimum auxin concentration for rooting Viburnum cariesii

18
(McMillan Browes, 1970: Miller and Smeal, 1972) . To determine
the optimum hormone range, Dirr and Heuser (1987) have

recommended testing with 0, 2,500, 5,000, 10,000, and 20,000 ppm

IBA.

Hartmann. and. Kester (1974) note 'that, in. general,
terminal cuttings root better than subterminal softwood
cuttings. Higher concentrations of endogenous hormones, and
softer, less differentiated tissue are suggested.asl possible
explanations.

The purpose of this study was to: 1) identify the optimum
range of auxin concentration for rooting Viburnum carlesii and 2)

determine the influence of cutting type (terminal and

subterminal) on rooting.
Materials and Methods. Shoots of Viburnum carlesii Helms. were

harvested on July 7, 1989 from 10-year-old field-grown stock

plants at Zelenka nursery in Grand Haven, Michigan. Growers
in Michigan normally root Viburnum carlesii between mid-June and

mid-July. Shoots consisted of soft, green, unhardened tissue
produced. that season, Shoots ‘were transported. to East
Lansing, Michigan in an ice-cooled, polystyrene container to
maintain turgor. They were later packaged in polyethylene
bags and stored at 5°C for two days until processing. Two
types of cuttings were made from the shoots: 1) terminal
cuttings that contained an active apical meristem and 2)
subterminal cuttings taken from directly below the apical

cutting (Figure 2.1). Each cutting was approximately 10-12

19

cm and contained two nodes. The basal set of leaves were
removed. Each cutting type was treated with 6 different auxin
concentrations, including a zero-auxin control (Table 2.1).
Auxin was applied as a 5-second quick dip composed of IBA and
NAA at a 2:1 ratio dissolved in 2-propanol. The control dip
contained only 2-propanol. The experimental design was a
randomized complete block design. It was arranged as a
factorial with 2 cutting types x 6 auxin levels x 4 blocks
(1200 total cuttings with 25 cuttings per block). Analysis
of variance was performed to determine the significance of
treatments and interaction. Arcsin transformation was used
on percent rooting data.

On July 10, 1989 the cuttings were stuck in a greenhouse
mist bench, 10 cm in depth, containing coarse grade perlite.
The greenhouse was set at 25°C/21°C day/night temperature,
although actual temperatures sometimes exceeded these set
points. ZMist was applied for 3 seconds every 10 minutes, from
0800 to 2000 HR. Bottom heat was maintained at 25°C with
mylar heating strips (Agritape, Ken-Bar Inc., Reading, MA.).
Cuttings were shaded with black polyethylene side curtains and
55 percent Saran shade cloth over top.

Eight weeks after sticking the cuttings, misting was
reduced to 6 hours and the shade cloth removed. At 10 weeks
the mist was discontinued and, thereafter, the cuttings were
watered manually. Once a week, 10 - 10 - 10 (NPK) water

soluble fertilizer, at 150 ppm, was applied when the cuttings

20
were watered. After 12 weeks the cuttings were harvested to
determine the rooting percentage and rated on a relative scale
of 1 to 5 (Figure 2.2) to determine rooting quality.

Results and Discussion No significant difference in percent
rooting was found following treatment with any of the auxin
concentrations measured 12 weeks after sticking (Table 2.2).
Furthermore, cutting type (terminal or subterminal) had no
affect on percent rooting. No interaction was found between
cutting type and auxin concentration. Averaged over all
treatments, rooting was 84% (Table 2.4). Auxin in the form
of a 2:1 IBA/NAA mixture did not improve percent rooting at
any of the applied concentrations. The auxin treatments may
have shortened the time to rooting, but because the cuttings
were not harvested until week twelve these results were not

noticedm Control cuttings rooted.a at high enough level (84%)
to question the necessity of auxin for rooting of Viburnum carlesii

softwood cuttings. The economic break-even point for
untreated cuttings has been suggested to be above 50 to 60%
rooting (Dirr and Heuser, 1987).

Auxin treatments had a significant influence on rooting

quality (Table 2.3). Auxin treatments with 1,000 ppm to
10,000 ppm IBA had significantly higher ratings compared to
the control and the 20,000 ppm IBA treatment (Table 2.4) .

At the highest IBA concentration (20,000 ppm IBA) rooting

quality was significantly reduced compared to other auxin

21
concentrations used” .Auxin levels above L000 ppm IBA.did.not
further improve root quality. From an economic standpoint,
there is no benefit in using more auxin than.necessary and for
this reason future investigation should examine auxin levels
below 1,000 ppm IBA/500 ppm NAA.

Our results indicate that cutting type, terminal or
subterminal, had no influence on the rooting or quality of
Viburnum carlesii cuttings. This is of practical benefit to
growers who use only tip cuttings. The additional use of
subterminal cuttings would double the amount of available
cutting material.

Any technique(s) that can improve the rooting percentage
and overall quality of Viburnum cw'lesii cuttings may help overcome
the high losses encountered during overwintering. An auxin
quick-dip of no more than 1,000 ppm IBA / 500 ppm NAA is
recommended for the satisfactory rooting of both terminal and

subterminal softwood.

22

Table 2.1. Auxin concentrations applied in parts per million
2-propanol solvent.

 

 

Treatment number IBA NAA Total auxin
1. Control 0 0 0
2. 1,000 500 1,500
3. 2,500 1,250 3,750
4. 5,000 2,500 7,500
5. 10,000 5,000 15,000

6. 20,000 10,000 30,000

 

23

Table 2.2. Analysis of ‘variance for’ percent rooting of
Vibumum carlesii as influenced by cutting type and auxin

 

 

concentration.‘
SOURCEy DF Sum of Squares Mean Square F‘Valuex
BLOCK 3 769.062 256.354 1.46
TYPE 1 163.430 163.430 0.93
CONC. 5 882.519 176.504 1.01
TYPE*CONC. 5 783.285 156.657 0.89
ERROR 33 5781.415 175.194

 

‘Data transformed by arcsin percentage transformation.

Y TYPE = cuttings type (terminal or subterminal),
CONC. = auxin concentration.

‘ All nonsignificant Prob. = .05.

Table 2.3. Analysis of variance for root quality rating of
Viburnum carlesii as influenced by cutting type and auxin

 

 

concentration.
SOURCE’ OF Sum of Squares Mean Square F Valuez
REP 3 0.351 0.117 0.78
TYPE 1 0.017 0.018 0.12“
CONC. 5 4.962 0.993 6.56
TYPE*CONC. 5 0.689 0.138 0.91
ERROR 33 4.991 0.151

 

’ Prob. = .025, ** highly significant
Y TYPE = cuttings type (terminal or subterminal),
CONC. = auxin concentration.

24

Table 2.4. The effect of auxin concentration on percent
rooting and rooting quality of Viburnum cariesii.z

 

 

Auxin Concentration Percent Mean Ratingy
(IBA / NAA ppm) Rootingx

Control 84.0 % 2.9 b
1,000 / 500 85.5 % 3.6 a
2,500 / 1,250 83.5 % 3.6 a
5,000 / 2,500 89.0 % 3.6 a
10,000 / 5,000 86.5 % 3.4 a
20,000 / 10,000 77.5 t 2.9 b

 

‘ The difference between terminal and subterminal cuttings

is nonsignificant and the results have been combined.
Y Mean seperation in columns by Duncan's multiple range
test, 5% level.
Percentages shown are not transformed, but statistics were
proformed using arcsin transformation. All treatments
nonsignificant for percent rooting.

X

25

Figure 2.1. Cutting types (terminal and subterminal) used in

rooting Vibumum carlesii. Leaves are not shown for better
visibility of the nodes.

e— TERMINAL cmmc

{- SUBTERHINRL CUTTING

 

26

Figure 2.2. Rating scale from 1-5 after 12 weeks for Vibumum
carlesii rooting quality.

VIBURNUM CARLESII
12 WEEKS

 

LIST OF REFERENCES

LIST OF REFERENCES

Dirr, M.A., and C.W. Heuser. The Reference Manual of Woody
Plant Propagation: From Seed to Tissue Culture. Athens:
Varsity Press, 1987.

Hartmann, 1LT. and D. Kester. Plant propagation: principles
and practices, Third Edition. Englewood Cliffs: Prentice-
Hall, 1975.

McMillan Browes, P.D.A. 1970. Notes on the propagation of
Viburnum. Inter. Plant Prop. Soc. 20:378-386.

Miller, J., and P. Smeal. 1972. Effect of propagation medium
and root promoting substances on rooting cuttings of five

Viburnum species. The Plant Propagator.18(1) :7-10.

Schaefer, M.P. Jr. 1985. Propagation of Viburnum carlesii Hybrids.
Inter. Plant Prop. Soc. 35:713-716.

27

CHAPTER III

THE EFFECT OF SUPPLEMENTAL LIGHTING AND PHOTOPERIOD ON
TERMINAL AND SUBTERMINAL Vibumum carlesii ROOTED

CUTTINGS AND SUBSEQUENT OVERWINTER SURVIVAL

28

ABSTRACT

Newly rooted terminal and subterminal Viburnum carlesii

cuttings were exposed to four light treatments: 1) natural
Michigan photoperiod, 2) 8-hour photoperiod and supplemental
HID light, 3) 8-hour photoperiod and supplemental HID light
plus a 4-hour night break and 4) 16-hour photoperiod and
supplemental HID light. Idght treatments lasted 55 days.

Percent budbreak and growth one week after budbreak were
measured, as well as post-storage budbreak and overwinter
survival. No difference in budbreak was found between cutting
type. Terminal cuttings had significantly more growth than
subterminal cuttings. Long day photoperiod and supplemental
light induced bud break and growth. The 16 hour treatment
induced the most budbreaks (97%) and the most growth (19 mm).
There was no difference between cutting type in post-storage
budbreak except for the 16 hour treatment. Subterminal
cuttings had the greatest survival rates if previously held
under 8 hours of supplemental light. Sixteen hours of
supplemental light reduced survival, especially for terminal
cuttings. Survival ranged from 82% to 100% if subterminal
cuttings had pre-storage growth induced by 8 hours of

supplemental light.

29

INTRODUCTION

Vibumum cariesii Hemsl. (Korean Spice Viburnum) is a popular

landscape shrub noted for it showy, fragrant flowers, burgundy
fall color, and neat habit. It is commonly propagated by
softwood cuttings because of the variability associated with
seed and a suckering problem encountered when grafted (Dirr,

1987) . A serious problem cited by growers and in the

literature is the poor overwinter survival rates of Viburnum

carlesii from softwood cuttings. Cuttings of many important
ornamental plants have been reported as difficult-to-

overwinter (Table 3.1) . Donnelly and Yawney (1972) stored Acer

saccharum cuttings under 6 different conditions including field
planting, cold cellar storage and refrigerated storage in pots
and bare-root in polyethylene bags. Cuttings planted directly
to the field in the fall had 100% mortality. All other
storage methods had survival rates ranging form 32% to 48%.

Cuttings potted in the fall and stored at 1°C in a controlled
temperature chamber had the best survival. Flint and McGuire

(1962) stored 8 Viburnum spp. under controlled temperature

conditions. The rooted cuttings were bare-rooted, placed in

polyethylene bags, and stored at either 0°C or 4°C for 5

30

31
months. Temperature influenced the survival in one half of
the species, where all, of these survived better at the lower
temperature. Viburnum carlesii 'Compactum' had statistically

higher survival at 0°C but with only 13% survival. Wood and
Cameron (1989) stored June-rooted, bare-root Viburnum carlesii

cuttings in polyethylene bags for five and 7 months in
controlled temperature chambers. The cuttings were stored at
temperatures of either 2.5°C or -2.5°C. Cuttings survival
ranged from only 1% to 8% regardless of treatment.
Characteristically many of these rooted cuttings appear
healthy at the onset of dormancy and throughout winter but in
the spring the buds either fail to break or break bud and
wither (Waxman, 1965: Donnelly and Yawney, 1981). The roots
appear healthy at the end of storage and initiate growth even
though the tops do not (McMillan Browes, 1970). The roots die
several weeks later. Stem splitting and darkened stems have
been reported at the end of storage (Hess, 1955; Flemer, 1982;
Smith. and. Treaster, 1985), indicative. of damage ‘to the

vascular cambium or vascular system.
Budbreak and Growth. It has been observed in some species

that are difficult to overwinter that if the cuttings break
bud before the onset of dormancy they survive at a higher rate
than those without growth (Smalley and Dirr, 1987: Waxman,

1951: Loach and‘Whalley, 1975; Harvis, 1982). It has not been
reported if budbreak improves the survival of Viburnum carlesii.

It is not fully understood how budbreak and the resulting

32
growth interacts with subsequent overwinter survival.
Budbreak may only be an indicator of a vigorous cutting that

would survive regardless of growth. Donnelly and Yawney
(1972) collected cuttings from eight different Acer saccharum

trees and found that cuttings from each tree had a different
capacity to form roots (ranging from 10% to 90%) . Rooted
cuttings originating from the trees that rooted easiest also
stored better.

Carbohydrate depletion is the most widely accepted
hypothesis for explaining the poor overwinter survival of
cuttings (Harvis, 1982; Loach and Whalley, 1975: Smalley and
Dirr, 1987: Waxman, 1951). It is thought that photosynthesis
from leaves on new growth replenishes carbohydrates depleted
during the rooting process, thus improving survival.

Deciduous plants depend on carbohydrates accumulated the
previous season for spring budbreak (Stassen etaL, 1981) .

The association between budbreak and improved survival
has generated much interest. Growers (Wells, 1970: Flemer,
1982) and researchers (Loach and Whalley, 1975: McConnell and
Herman, 1980: Smalley and Dirr, 1987: Smith and Treaster,
1985) have worked with different plant species and have
artificially attempted to force growth with light treatments
and growth hormones. Results have been mixed in both percent
budbreak and percent overwinter survival.

Smalley and Dirr (1987) studied the effect of photoperiod

on budbreak and overwinter survival of Acer rubrum 'October

33
Glory' cuttings rooted in June and August. Carbohydrates
were analyzed to determine if they influenced overwintering.
Short day and night-interrupted, long day photoperiod were
studied. June cuttings received photoperiod treatments from
July 25 until October 22, 1984 (89 days). August cuttings
received ‘photoperiod treatments from September 10 until
October 22, 1984 (32 days). The night break was produced by

an incandescent lamp with a light intensity of 3 to 5 umol m'

2 1

sec'. Cuttings were moved outside and held for 42 days and
then stored in a double poly-house maintained at or above -
1°C for 165 days. The June cuttings had significantly more
plants which broke bud (60%) under the long day (night
interruption) photoperiod compared to (43%) short day
conditions. However, no significant difference in winter
survival was found between long day (81%) and short day (82%)
treatments. In the August cuttings, neither treatment forced
new growth and yet both had survival rates greater than 90%.
Regardless of treatment, however, all cuttings that broke bud
survived the winter. Those that did not break bud survived
at a higher rate under the short day treatment (68%) than did
the cutting under long days (52%). Analysis of carbohydrates
revealed that both soluble sugars and starch were greater in
the roots of plants that broke bud over those that did not
break bud. No difference in carbohydrates was found in
cuttings that did not break bud within the two photoperiod.

Even though Smalley and Dirr's work showed that cuttings that

34
broke bud had higher levels of root carbohydrates there is no
proof that the difference is responsible for increased
survival. Growth and its physiological consequences are more
complex than increased carbohydrates alone. Donnelly and
Yawney (1972) also investigated the relationship between
carbohydrates and overwinter survival. Total carbohydrates
(Percent dry weight) were found to be higher (20%) in 1-year
old Acer saccharum seedlings and than in rooted cuttings (10%) .
Dormant feedings of sugar and nutrient solutions, however,

did not improve the survival of Acer sacchanim rooted cuttings

stored for two months at 1°C (Donnelly and Yawney, 1972) .
Hormones have also been used to force growth in efforts
to improve survival rates. Carthaigh (1983) significantly
increased budbreak and growth of Prunus triloba with 500 ppm GA3
but increased overwinter survival only moderately (no
statistics used). McConnell and Herman (1980) used two
concentrations of GA3 (1000 and 4000 ppm) as well as two
levels of N-6-benzyladenine (200 and 1000 ppm) to induce
growth on Salixpentandra L. and Viburnum lantana L. Gibberellic acid
was found to significantly improve budbreak for both species
but had little effect on overwinter survival. Benzyladenine
treatments did not improve budbreak but it did show a small
but significant increase (15%) in survival over the control.
Loach and Whalley (1975) examined the effects of GA},
extended photoperiod (low intensity, dusk to dawn), and a

combination of extended photoperiod and CO2 on the survival

35

of Betula pendula and Berberis thunbergii 'Atropurpurea Rosea' . For
birch, extended photoperiod with supplemental CO2 and the
extended photoperiod treatment showed the highest survival
rates (70% and 62% respectively) compared to GA3 (21%) and
control (16%). In barberry (which is known to be difficult
to overwinter), extended photoperiod had the best survival
rate (87%) while all other treatments were only slightly
better than the control (55%). In both experiments survival
rates loosely correlated with the number of leaves per plant
produced prior to storage under each treatment, however, no
statistics were used.

The problem of overwinter survival is particularly severe

in the genus Viburnum (Dirr, 1987: McMillan Browes, 1970:

Smith and Treaster, 1985: Waxman, 1951) , specifically Viburnum

cariseii Helms and its hybrids. As is the case with many of the
species that are difficult to overwinter, long days cause
continuous vegetative growth of Viburnum (Nitsch, 1975) .
Several researchers have studied the effect of photoperiod on
the overwinter survival of Viburnum.

Bhella and Moore (1980) who studied the propagation of

Viburnum lantana L. 'Mohican' , Viburnum x rhytidophylloides Sur.

'Alleghany' and Vime sargentii Koehne 'Onondaga' found the
survival rate to be greater than 95 percent for all cultivars
when subjected to a high intensity 18 hour photoperiod.

However, the plants were never allowed to go dormant and no

36
control plants were used.

Downs and Piringer (1958) examined the response of five
different Viburnum spp. (including Viburnum carlesii Hemsl.) under

four different photoperiod (8, 12, 14, and 16 hours) after 24
weeks. Stem growth was significantly greater under
photoperiod longer than 12 hours. Plants under 14 and 16 hour
photoperiod averaged 101 cm of growth per plant while the 8
and 12 hour treatments averaged 39 cm per plant. The plants
were overwintered in the field with a recorded low temperature
of 13°C. All plants survived the winter regardless of
photoperiod treatment. It should be noted that the
experimental plants used had been rooted the previous summer

and overwintered in the field before being subjected to
photoperiod treatments. This suggests that Viburnum cariesii
responds to a long day photoperiod over 12 hours and that
overwintering death is related to specifically to newly
propagation rooted cuttings. Wood and Cameron (unpublished)
also found that 1-year-old Vibumum carlesii plants overwintered
at rates greater than 90%.

Pflhogni Several factors have been identified. that

contribute to poor overwinter survival of cuttings. High
nitrogen levels can cause problems in overwintering softwood
cuttings. Stimart and Goodman (1985) studied the effect of

nitrogen on the overwinter survival under two different

photoperiod. Working with Acerpalmatum 'Bloodgood' and Camus

37
florida forma rubra they subjected cuttings to either long day or

day neutral photoperiod while treating them with two levels
of nitrogen. Cuttings were rooted in mid-June, transplanted
and held under shade cloth in a greenhouse until late
September. The light treatment consisted of an 18 hour
photoperiod produced by incandescent bulbs (9 umoles s—l m-
2). The plants were given a constant feed of either 0 or 200
ppm nitrogen (NH,NO3) . Plants were moved outside in mid-
November for hardening off. In mid December the plants were
covered with covered with microfoam and sash. The microfoam
was removed in mid-March and survival rates were calculated
one month later. Overwinter survival was highest in both
species (100% and 98% respectively) if the plants had growth
before dormancy and received no nitrogen. The author stated
that ”No detectable patterns of overwinter survival were
related to previous season photoperiod treatment” although no
data was presented on the growth response to photoperiod and
no statistics were presented. Nitrogen decreased survival
rates for both species under both photoperiod if no growth was
initiated before dormancy (a combined average under 12%).
Growth appeared to counteract the affect of nitrogen resulting
in a combined average of 81% survival. The adverse affect of
nitrogen on cold hardiness is well known. Weiser (1965)
states that nitrogen increases cold injury for two reasons:
1) late autumn growth promoted by nitrogen delays hardening,

and 2) nitrogen induced growth depletes carbohydrate reserves.

38
Statistically contradictory to this reasoning, Stimart and
Goodman's cuttings receiving nitrogen that grew survived at

higher rates than those that did not grow.
Hardening. Proper hardening can also be a source of

overwintering problems in newly rooted cuttings, especially
if growth techniques have been used after rooting. Smith and
Treaster (1985) studied the effects of extended photoperiod

(high intensity night interruption) on growth and survival of
mid-June propagated Viburnum opulus 'Nanum' cuttings. In mid-

July cuttings (except for controls) were place under high
pressure sodium lamps that operated from 10:00 p.m. to 2:00
a.m. each night. Every two weeks 25 plants were removed (for
a total of twelve weeks). The plants were stored in an
unheated poly-house from mid-November to the first week of
May; Long days resulted in increased growth through the first
eight weeks. Survival was highest (68%) for plants left under
lights for 8 weeks compared to the control (24%). Survival
decreased under the 10 week (36%) and 12 week (12%)
treatments. Leaf drop was measured in storage as an
indication of hardening. The 8 week treatment had 20% leaf
drop at the end of February. The remaining leaves were brown
and attached to the plant. Control plants had 100% leaf drop
and the 12 week plants had green leaves and no leaf drop.
Clearly the induction of growth after rooting can inhibit the

proper cold hardening of newly rooted cutting.

Cuttings Material. Cutting type has been reported to

39

influence overwinter survival. Donnelly and Yawney (1972)
found that longer Acer saccharum cuttings rooted and survived
better than shorter cuttings. Smalley and Dirr (1987b)
working with Acer rubrum found no difference in overwinter

survival between terminal cuttings with 3 to 5 nodes,
subterminal cuttings with one node, and subterminal cuttings
with. three nodes“ Subterminal three node cuttings had
significantly greater lateral budbreak but all cutting types

survived above 92 percent.
Root Disturbance. Fall transplanting has been implicated as
a factor in lowering overwinter survival. Fordham (1976,

1982) claims improved overwinter survival of Hamamelis spp.

and Stewartia spp. cuttings if left undisturbed until the
following spring. English (1981) makes the same claim for

Acer rubrum cuttings. Dirr (1987 ) recommends non-disturbance

for Acer, Hamamelis, Stewartia and Viburnum species. Only Donnelly

and Yawney (1972) have published experimental results on

transplanting and found no statistical differences in survival
between Acer saccharum cuttings transplanted and those left

undisturbed. Still, some growers leave rooted cuttings in
propagation containers for up to two years before
transplanting (Dirr, 1987) . Further research on transplant
shock is needed to decisively separate observation and fact.

Disease. Fungi can be serious problem for plants

overwintering in both common and refrigerated storage

40

facilities (Davidson etaL, 1981). Flint and McGuire (1962)

found a 54% increase in survival of Viburnum cariesii compactum if

cuttings were treated with Captan prior to refrigerated
storage at 0°C. However, no attempt was made to isolate or
identify molds.

Research on the overwinter survival of cuttings has been
limited and varied. Due to the time consuming nature and poor
funding of woody ornamental research, few experiments have
been repeated. Adding to the confusion, variability occurs
in overwinter survival rates from year to year, crop to crop,
and from grower to grower. The use of different storage
methods, propagation techniques and plant species also serves
to cloud the investigation of overwintering death of rooted
cuttings.

Why cuttings with growth prior to dormancy survive better
that those without growth is not fully understood. Budbreak
and growth are very complex physiological processes that
result in many anatomical, physiological and biochemical
changes. Although new growth has been shown to improve
carbohydrate levels in some cases (Smalley and Dirr, 1987)
it can also deplete carbohydrates (Stassen etaL, 1981). It
has not, however, been demonstrated that cuttings that are
difficult to store have insufficient carbohydrates to
overwinter.

Softwood cuttings are taken in the spring when stems are

actively growing. It is separated from its root system and

41

the water, nutrients, and hormones the roots once supplied.
Cuttings encounter many forms of stress throughout rooting and
storage. What is viewed as one causal agent may be several
individual or related factors that contribute to the low
survival rate of cuttings.

The purpose of this experiment was to determine the
influence of high intensity supplemental lighting, and

photoperiod (long and short days) on the overwinter survival

of terminal and subterminal Viburnum carlesii rooted cuttings.

MATERIALS AND METHODS

Plant material. On 16 October 1989, 200 terminal and 200

subterminal two-node Viburnum carlesii cuttings were randomly

selected from uniform, well rooted material propagated July
5, 1989. The cuttings were potted into four-inch clay pots
in a peat-perlite-vermiculite mix. Cuttings were held in a

greenhouse with a day/night temperature of 25°C/21°C.
Light treatments. On October 20, fifty cuttings of each type

were randomly assigned to one of four light treatments: 1)
natural light and day length (control), 2) eight hour
supplemental lighting and photoperiod (8 HID), 3) eight hour
supplemental lighting and photoperiod plus a four hour night
break (8 HID + NB) and 4) sixteen hour supplemental light and
photoperiod (16 HID). All supplemental light was provided by
high pressure sodium (HID) lamps having a light intensity of
100 to 150 umole m'2 sec"1 at plant height. Supplemental
lighting was initiated at 0800 HR and ended at 1600 HR except
for the 16 HID treatment which ended at 2400 HR. The
photoperiod of the 8 HID and the 8 HR + NB treatments were
maintained by covering the plants with black cloth from 1600
until 0800 HR. The four hour night break was provided by two

75 Watt incandescent lights, with a light intensity of 10 -

42

43

2 1

22 umole m' sec’. The lamps were suspended 60 cm above the
jplants and under the black cloth from 2200 to 0200 HR. The
:night break resulted in a maximum temperature increase of 4%:
at plant level (data not shown). A back plastic barrier
separated the control group from the other light treatments.

All plants were fertilized when watered with 150 ppm 10
- 10 - 10 (NPK) water soluble fertilizer. All plants were
watered once a week with straight water to leach out excess
soluble salts. Fertilization was discontinued after 30 days.

On December 13, 1990 final budbreak data were collected. Date

of budbreak was noted for each cutting. Stem length was

measured 7 days after each plant broke bud. Because Viburnum

awflmfi has no bud scales, budbreak was arbitrarily defined as

the first visible sign of the upper leaf surface as a leaf
unfolded. Differences in percent.budbreak between treatments
were statistically analyzed by two-way chi-squared contingency
tables because the results were binomial. cuttings either
break bud or they do not. Analysis of variance for week one
growth data was by the (SAS) General Linear Model (GLM)
procedure because not all plants broke bud, yielding unequal
sample sizes.

All of the cuttings, except 50 control and 50, 16 HID
cuttings, were tagged if they had growth. They were held in
a greenhouse at 25°C/21°C under normal Michigan photoperiod
in preparation for hardening. The 50 control and 50, 16 HID

cuttings (each containing equal numbers of the two cutting

44
types) were left under their respective light treatments.
Survival rates for these cuttings were calculated on the same

day the stored cuttings were evaluated for survival.

(hwnnnang. On.January 15, 1990, approximately one month

after removal from supplemental light, 20 Viburnum carlesii

cuttings ‘were randomly selected from. each of the eight
treatments and placed in a 5°C controlled temperature chamber
for hardening. The cuttings received an 8 hour photoperiod
supplied by florescent lamps delivering a light intensity of

45 to 70 umole m'zsec'1

for 3 months and watered as necessary.
On April 5, 1990 the cuttings were bare-rooted, placed into
4 mil. polyethylene bags and stored for 75 days at 0W3. On
June 21, 1990 cuttings were transplanted into 6 in. clay pots,
watered and placed under 55% shade cloth and misted regularly.
Plant budbreak was tabulated at one week and plant survival
was observed two weeks after removal from storage.

Statistical analysis was by chi- squared contingency tables

for both budbreak and survival.

RESULTS

Forced budbreak. The difference in percent budbreak between

terminal and subterminal cuttings for each light treatment was
primarily nonsignificant over the 55 day treatment period
(Figure 3.1) . Slight differences were found at day 30 and day
40 under the 8 hour photoperiod and at day 30 under the 8 HID
+ NB treatment but all differences were non-significant by 55
days. Averaged over all light treatments there was no
statistical difference in budbreak between cutting type within
the 55 day period. At the end of the treatment period (55
days) 101 out of 200 terminal cuttings broke while 105
subterminal cuttings broke over all treatments (Figure 3.2).

Light treatments had a pronounced influence on the number
of plants breaking bud and the rate at which plants broke bud
(Figure 3.3) . The 16 HID treatment, which combined long days
and high light intensity, induced significantly more breaks
(97% at 55 days) and induced them quicker (50% at day 18) than
all other treatments (Table 3.2). The 8 HID + NB treatment,
which also had a long day photoperiod but a lower light
intensity, had fewer plants break after 55 days and broke at
a slower rate (50% at day 35) compared to the 16 HID
treatment. Basically no statistical difference was found

between the two short day treatments (control and the 8 HID)

45

46
Ibased on chi-square analysis even though the 8 HID treatment
Ihad.a higher light intensity (Table 3.2). The simulated long
days produced by the 8 HID + NB treatment significantly
increased.the amount of plants that.broke bud (68% at 55 days)
(compared to the 8 HR HID treatment (27% at 55 days) which had

‘the same light intensity.
Forced growth. Cutting type and light treatment both

statistically influenced the amount of growth produced one
week after budbreak (Table 3.4). There was no statistical
interaction. The 16 HR HID treatment produced the greatest
‘mean growth per plant at one week (19 mm) and was
significantly greater than the 8 HR + NB treatment (12 mm)
(Figure 3.3). Both long day treatments (16 HR HID and 8 HR
4+ NB) induced significantly more growth than the short day
treatments (8 HR and 8 HR + NB) which were statistically the
same as one another. Variability in plant growth at one week
was relatively high (C.V.=82.9).

Mean growth per plant for terminal cuttings (17 mm) was
significantly greater than for subterminal cuttings (11 mm)
at one week after budbreak (Figure 3.5).

The cuttings that remained in the greenhouse under their
original light treatments, (control and 16 HID never hardened
or stored) from October 20, 1989 to June 27, 1990, had 100%

survival (data not shown).
Post-storage performance. Subterminal control and subterminal

8 HID + NB had the greatest amount of cuttings break bud (80%

 

47

each) following bare-root storage and both.were significantly
greater than the terminal 16 HID cuttings which had the least
amount of budbreaks (25%, Figure 3.6) . The subterminal 8 HID
and terminal control treatments also had significantly more
cuttings. break; bud (65% and 70% respectively) than. the
terminal 16 HID treatment (Table 3.4). Averaged over all
treatments, 60% of all cuttings broke bud.

Not all cuttings that broke bud after storage went on
to survive. An additional 22% more cuttings wilted and died
by week two (Figure 3.6). Control cuttings, both terminal
and subterminal, and all other terminal treatments suffered
considerable losses after breaking bud. Ultimately, the
subterminal 8 HID + NB treatment had the greatest amount of
cuttings survive (75%) . Statistically this treatment had
greater survival than all of the other treatments except
subterminal 8 HID (50%, Table 3.5) . The subterminal cuttings
in all treatments, except the control, had greater survival
statistically, than the terminal cuttings. Terminal 16 HID
cuttings had the lowest survival (10%) and were statistically
lower than all subterminal treatments and the terminal
control. Averaged over all light treatments subterminal
cuttings had a higher survival rate (51%) than terminal
cuttings (25%). When averaged over all treatments survival
was only 38%.

Cuttings with forced growth survived at statistically

higher survival rates than those without growth under three

 

48

'treatments: 1) terminal 8 HID, 2) subterminal 8 HID and 3)
subterminal 8 HID + NB (Table 3.6) . Subterminal cuttings with
growth survived at significantly higher levels than terminal
cuttings in the 8 HID + NB and 16 HID treatments.

Subterminal 8 HID + NB cuttings with growth survived at the
highest rate (100%). Statistically, this group of cuttings
Ihad.a survival rate greater than all other treatments, growth
or'no growth, except for the subterminal 8 HID cuttings with
growth (82%) . Subterminal 8 HID cuttings with growth had
statistically greater survival than all other groups except
terminal 8 HID cuttings with growth and 8 HID + NB cuttings
‘with growth. No significant difference existed between the
control cuttings, terminal or subterminal, even if they had
growth. Averaged over all light treatments subterminal
cuttings with growth had the highest survival rate ( 65%) .
When also averaged over cutting type cuttings with growth
survived at 48% while those with out growth had only 25%

survival.

DISCUSSION

The results of this experiment clearly demonstrate the
difficulty of overwintering dormant Viburnum carlesii cuttings.

Cutting survival was only 38% (Table 3.6) when averaged over
all treatments. Cuttings held in a warm greenhouse for the
duration of winter all survived. This suggests overwintering
problems occur only if the cuttings are dormant and stored at
low temperatures.

Cuttings exhibited two types of symptoms when failing to
survive after storage: 1) they either failed to break bud or
2) they broke bud and then later wilted and died. This may

also indicate that more than one factor is involved.

Sclerotium of Sclerotinia sp. (White mold), Pythium sp. and

.Ewmmhnisp. were identified, on all treatments groups at the
end storage, by the Michigan State University Diagnostic
Clinic. Stem lesions were visible on only a few plants.

Sclerotinia, and damping of diseases can produce stem splitting

and a darkening of the stems (Agrios, 1988) . Several authors
have reported stem splitting and darkened stems after
overwintering cuttings (Flemer,1982: Hess,1955; Smith and

Treaster,1985). Flint and McGuire (1962) significantly

49

50
improved the survival rates of Viburnum spp. by treating the

cuttings with 5% Captan. However, no attempt was made to
identify molds in that study. Fungal disease may not be the
primary cause of overwintering death for these cuttings. It
may have been secondary infection or perhaps one of several
factors contributing to cutting death.

Cutting type, and its influence on budbreak, was
investigated for several reasons. It *was thought that
subterminal cuttings might have an advantage because the
lateral buds are formed chronologically earlier than those on
terminal cuttings. Buds that are on the stock plant longer
may have reached a higher state of maturity, thus increasing
their ability to break when forced after storage. Also in
question was the role of the apical meristem in controlling
budbreak. The stem apex can inhibit the growth of lateral
buds and.its removal eliminates the inhibition.(Martin, 1987).
Subterminal cuttings did not respond as the above hypothesis
would indicate. The only sign that subterminal cuttings had
greater breaking ability was in the 8 HR HID treatment at days
20 and 30 (Figure 3.1). In all other treatments there was
either no difference or the terminal cuttings had more breaks.
Also there was no statistical difference in budbreak after
storage between the two types of cuttings within each light
treatment (Table 3.4).

Cutting type did however have an influence on survival.

Subterminal cuttings given supplemental lighting (8 HID, 8

51

HID + NB and 16 HID) had a statistical advantage over terminal
cuttings within each light regime (Table 3.5). Cutting type
had no influence on the post-storage budbreak or survival of
the control cuttings. This indicates an interaction between
the supplemental light and the subterminal cutting. Larger
subterminal cuttings may have a greater capacity to transport
and store assimilates produced by high light levels than do
smaller, less mature terminal stems.

It has been suggested that forced growth before dormancy
will improve the overwinter survival of cuttings. The

results of this research indicate that forced growth.will not
improve the survival of Viburnum, carlesii cuttings under all

conditions. Statistically, terminal 16 HID cuttings had the
poorest survival (Figure 3.6) of all the treatments even
though this light treatment induced the greatest amount of
budbreaks and growth (Figures 3.3 and 3.4). Extremely long
exposure to high light levels and forced growth has been shown
to adversely affect the fall hardening process and overwinter

survival. Smith and Treaster (1985) reduced the overwinter
survival of Viburnum opulus cuttings by subjecting them to 12

weeks of high intensity light breaks. The forcing of extended
stem growth by long photoperiod can prevent plant hardening
even after returning them to short days (Levitt, 1980) .
Cuttings in this study were held under naturally short days
in a warm greenhouse for one month and were then held at 5W3,

under an 8 hour photoperiod, for three months before storing

52
them at 0°C. Cold hardiness should not have been a factor in
reducing the survival of the 16 HID cuttings since they had
considerable time under hardening conditions and were store
at only 0°C. Extended periods of rapid growth followed by

prolonged short days can reduce reserve carbohydrates (Tumanov
et at, 1972) . Actively growing plant tissue can be a strong

sink for assimilates. If the net energy balance of the
cutting is not positive before encountering low light
conditions, little or no assimilate is reserved for spring
growth.

Under some circumstances growth improved survival. The
best overwinter survival was in subterminal cuttings under
the 8 HID + NB (75%) and the 8 HID (50%) light treatments
(Figure 3.6) . If the subterminal cuttings under these two
light treatments had new growth prior to storage, survival
rates were greater than those without growth (Table 3.6) .
Subterminal cuttings in the 8 HID + NB treatment had 100%
survival if they had growth, compared to only 33% survival of
those without growth. Subterminal cuttings in the 8 HID
treatment survived at 82% with forced growth and only 11%
survival for cuttings without growth. Terminal cuttings in
the 8 HID treatment had greater survival (57%) with growth
and no survival without growth. In the control group there
were no statistical differences between terminal or
subterminal cuttings with or without growth. Growth appears

only to improve survival following treatments with specific

 

53
levels of light. It also appears that subterminal cuttings
have a survival advantage under long photoperiod.
From a practical standpoint subterminal cuttings under
‘the 8 HID + NB treatments should yield the highest number of
cuttings surviving the winter. For example, based on the

techniques and statistical results of this research, if a
grower stuck 1200 subterminal Viburnum carlesii cuttings

.approximately 1000 cuttings would root (Chapter 2). If the
1000 cuttings were then given 55 days of 8 hour supplemental
HID light with a 4 hour night break approximately 700 plants
(70%) would break bud and 300‘would.notm The following spring
814 cuttings would have survived.. Overall this represents a

68%

1200 cuttings stuckxmmng = approximately lOOOrootedcuttings.
1000 cuttingsx'm'b forced budbreak = 700 cuttings withgrowthandMWIthontgwwth
[70011005 survival with youth] 4» [30013s%snrvlvalw/o youth] = 814 cuttings
(814wttings/12003tuck)x100 = 68%successrate

success rate, which is above the economic break-point (50% to
60%) that Dirr'and.Heuser (1987) claimed was necessary for the
profitable production of rooted cuttings. If a grower stuck
1200 terminal cuttings and held them under natural Michigan
photoperiod only 315 cuttings would successfully overwinter,

exhibiting only a 26% success rate.

54

1200 cuttings stuck x 84% rooting 8 approximately 1000 rooted cuttings
(0.25 + 0.38 / 2) = 31.5% ' survival rate averaged because growth was nonsignificant
1000 rooted cuttings x 31.5% survival rate = 315 cuttings

(315 cuttings surviving] 1200 stuck) x 100 = 26% success rate

While the results of this study do not totally solve the
problem of overwintering Viburnum carlesii, they do offer new
insight into the problem and a starting-point for future
research. Viburnum Cariesii has been shown to be an excellent

system test plant because it roots easily, is extremely
difficult to overwinter and breaks bud readily under long
photoperiod. Future research should be conducted to verify
the positive interaction found between supplemental light,
growth and subterminal cuttings. An anatomical study of
stems may shed light on why subterminal cuttings survived at
higher rates under supplemental light. Sugar feeding
experiments and other methods of carbohydrate manipulation
would provide greater insight into the role carbohydrates play

in the overwinter survival of cuttings. Hardwood cutting
propagation (late season rooting) of Viburnum carlesii should also

be studied since anpublished reports can be found to document
if they also exhibit overwintering problems. And finally the
role of transplanting and root disturbance should be
investigated by scientific methods to either verify or
disclaim. the reports that post-propagation transplanting

contributes to the reduced overwinter survival of cuttings.

 

55

 

 

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Table 3.2.

56

Budbreaks of Viburnum carlesii induced by light

treatments averaged over cutting type. Budbreak averaged

 

 

 

 

 

 

over cutting type . Chi-square contingency table
comparisons at days 20, 30, 40 and 55. n=100.
TREATMENT DAY
20 30 4O 55
Control 9 11 12 16
8 HID 14 20 24 27
8 HID+NB 25 44 63 68
16 HID 56 83 91 97
CONTRAST DAY
Tmt 1 Tmt 2 20 3O 40 55
Control 8 HID 1.233. 3.093: 4.80. 3. 59ns
m “it
Control 8 HID+NB 9.07 27.31 55.49 55.50
i” m t“
Control 16 HID 50-35. 104-05... 124.93”. 133.48.”
8 HID 8 HID+NB 3.85 13.24 30.94 33.70
m m m m
8 HID 16 HID 38.77 79.45 91.85 103.99
m t“ m m
8 HID+NB l6 HID 19.94 32.81 22.13 29.13

 

Tab x2.05,1,=3.84, .025-—-5.02, .001=6.63

57

Table 3.3. Analysis of variance for stem growth of Viburnum
awflnfi at one week after budbreak.z

 

 

Sourcex OF 8.8. Mean Sq. F Valuey
Light 3 6420.06 2140.02 16.95::
Cutting 1 1399.96 1399.96 11.09
Light*Cut 3 628.01 209.34 1.66
Error 198 24992.91 126.27

 

2 SAS GLM procedure, type I SS. adjusted for nonuniform
observations.

y *** Highly significant at .001 prob.

x Light=1ight treatments, Cutting and Cut=cutting type.

58

 

 

 

Table 3.4. Budbreak of Viburnum carlesii at one week after 75
days of storage at 0°C. Chi-square contingency table
comparisons.

Contrast

Treatment 1 Treatment 2 Chi square value‘

'1'. control T. 16 HID 5.59;

S. control 8. 16 HID 7.81.

T. 16 HID S. 8 HID 4.58“”

T. 16 HID S. 8 HID+NB 7.81

 

X2=u).05=3.84, .025=5.02, .Ol=6.63

 

 

 

Table 3.5. Survival of Viburnum carlesii at two weeks after 75
days of storage at 0°C. Chi-square contingency table
comparisonsz.

Contrast
Treatment 1 Treatment 2 Chi square valuez
*
T. Control S. 8 HID+NB 5.01.
T. Control T. 16 HID 4.80“
8. Control 8. 8 HID+NB 6.47.
T. 8 HID S. 8 HID 3.96“*
T. 8 HID S. 8 HID+NB 12.13“”
S. 8 HID T. 16 HID 7.62".
T. 8 HID+NB S. 8 HID+NB 8.12“”
S. 8 HID+NB T. 16 HID 17.27“
T. 16 HID S. 16 HID 6.14

 

X2=(1).05=3 .84, . 025=5. 02 , . 01=6. 63
z nonsignificant comparisions are not shown

59

Table 3.6. Percent survival of cuttings of Viburnum carlesii
after 75 days storage as a function of light treatment
and cutting type with regard to the presence or abscence
of growth prior to storage. Relavent chi-square
contingency table comparisons presented at the bottom of

 

 

 

 

the table.

Treatment % Survival Growth' Egrggg§_§gryiyalz
response n term. subterm. total

Control 38% growth 10 50 1 33 ° 40%
none 30 38 2 36 w 37%

8 HID 33% growth ‘ 18 57 3 82 " 72%
none 22 0 5 11 n 8%

8 HID+NB 53% growth 24 33 100 u 67%
none 16 25 ‘7’ 38 1“ 31%

16 HID 28% growth 40 1o 45 5 28%
none 0 ---8 ---16 ""
growth 92 28% 65% 48%
none 68 21% 29% 25%

Total 160 25% 51% 38%

 

z Growth response defined as new budbreaks induced by light
treatments before storage.

y Relavent chi-square comparisons at .05 prob., 1 df.:

Comparisons between 1,2,9,10 all nonsignificant.
Comparisons between 11+13, 3+11, 4+12, 6+14 and 5+6 are
nonsignificant.

Comparisons between 3+4, 11+12, 4+11, 5+13,

13+14, and 7+15 are significant.

60

Figure. 3.1. Cumulative budbreak response of terminal and

subterminal rooted of Viburnum carlesii cuttings under four-
55 day light treatments. Chi-square contingency table
comparisons between terminal and subterminal cuttings
(located at the bottom of each graph) with a tabular chi-
square value of 3.84, 1 degree of freedom and * .05 prob.

8 HOURS HID

CONTROL - NO HID

PERCENT PLANT BUDBREAK

 

 

 

 

 

 

 

 

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61

DAYS OF EXPOSURE

DAYS OF EXPOSURE

16 HOURS HID

8 HOURS HID + NIGHT BREAK

 

 

 

 

 

 

 

 

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DAYS OF EXPOSURE

DAYS OF EXPOSURE

62

 

 

 

 

 

ZOO IOO
180‘ 0—0 TERMINAL CUTTINGS ‘
g _ B——EI SUBTERMINAL CUTTINGS .
m 160— X20105 TAB:3.84 -— 80 U
L” ‘ 1 m
x _ _
O 140 (3%
01 ‘ ‘ m
CD 120— ‘ESOZ
2 ~ . ——1
I 100— - w
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‘ 0.83 0.17 0.04 0.04 X2 ‘0
O ' ‘I‘ . I . 1 7 I ' 1 r
0 IO 2O 30 40 SO 60

DAYS OF EXPOSURE

Figure 3.2. Cumulative plant budbreak response of terminal and

subterminal rooted cuttings of Viburnum carlesii averaged over
four different 55 day light treatments. Chi-square
contingency table comparisons between terminal and
subterminal cuttings (located at the bottom of graph)
with a tabular chi square value of 3.84, 1 degree of
freedom and .05 prob.

63

 

1OO
08x9
90— 0000 16 HOURS J

PERCENT BUDBREAK

 

 

 

 

 

DAYS OF EXPOSURE

Figure. 3.3. Cummulative plant budbreak response of rooted

cuttings of Viburnum carlesii under four different 55-day
light treatments averaged over terminal and subterminal
cutting types.

64

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A 35
E q ‘2
E : “ :
V :50— _
x : :
L1J ~ .
L; 251 SD 1
(r 20; 1 L
LE : :
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< 15: j
E 3 I
3 101 \\ .:
O : \\ :
2:9 : T \\ :
5— T I \\ _— —I
2 : \\ 1
If : \\ 3
m 0 0 CONTROL 8 HID 8 HI“+NB 16 HID

Figure. 3.4. Mean stem growth per plant Viburnum carlesii 1 week
after induced budbreak under four different 55-day light
treatments and averaged over terminal and subterminal
cutting type.

65

 

 

 

 

 

 

 

 

 

 

25
Q 2 E: TERMINAL :
8 : [Z] SUBTERMINAL :
L 20~ —
.0 . 3
'g . .
En : :
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LDC) . 3
2% 10: 50:05 / ;
E: . / -
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E 57 /// ‘
E ¢ 2
0 _ / ‘

Figure. 3.5. Mean stem growth of Viburnum carlesii terminal and

subterminal cuttings (per plant 1 week after budbreak and
averaged over four different 55-day light treatments).

66

 

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Figure. 3.6. Percent budbreak and survival of terminal and

subterminal cuttings of Viburnum carlesii that had been
treated with four different 55-day light treatments and
stored for 75 days at 0°C.

LIST OF REFERENCES

LIST OF REFERENCES

Agrios, G.N. Plant Pathology. San Diego: Academic Press. pp.
97-98 and 430-434.

Anstey, J.M. 1969..4an from cuttings. Proc. Intl. Plant Prop.
Soc. 19:211-213.

Bhella, H.S. and J. Moore. 1980. Vegetative propagation of

Viburnum cv. Alleghany, Mohican, and Onodaga. Plant
Propagator 26:5-9.

Brotzman, T.C. 1980. Some Trials in the propagation of Acer
Species by cutting. Proc. Intl. Plant Prop. Soc. 30: 342-
345.

Carthaigh, D.M. 1983. Gibberellic acid breaks summer dormancy

in rooted cuttings of flowering almond (Prunus triloba) . The
Plant Propagator 29:12-14.

Dirr, M.A., and C.W. Heuser. The Reference Manual of WCody
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