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EFFECT OF ENVIRONMENTAL FACTORS
(2-CHLOROETHYL) PHOSPHONIC ACID AND SILVER THIOSULFATE
ON BUD ABORTION IN TAGETES ERECTA L. CV. MOONSHOT

 

By

Oimitris George Gavrilis

A THESIS

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

MASTER OF SCIENCE

Department of Horticulture

1983

V

ABSTRACT

EFFECT OF ENVIRONMENTAL FACTORS
(2-CHLOROETHYL) PHOSPHONIC ACID AND SILVER THIOSULFATE
ON BUD ABORTION IN TAGETES ERECTA L. CV. MOONSHOT

 

By

Dimitris George Gavrilis

Temperatures above 23°C alone or interacting with low quantum flux
(QFD<4OO uEm‘ZS") and water stress was the main environmental factor

favoring apical and lateral bud abortion in Tagetes erecta L. cv.

 

Moonshot. These environmental factors appear to influence endogenous
ethylene production that accelerates maturity of the apical bud which
ceases its development and finally aborts. The abortion of the apical
bud results in an outgrowth of laterals which subsequently show the
same abortion symptoms.

Silver Thiosulfate (STS) applied to the foliage at 50mg of Silver
Nitrate (AgN03) in 292mg of Sodium Thiosulfate 30 to 45 days after
sowing (during terminal bud development) prevented apical and lateral
bud abortion in the presence of (2-chloroethyl) phophonic acid or

environmental conditions favoring ethylene synthesis and action.

DEDICATION

To Rena, George and Tonia

ii

ACKNOWLEDGMENTS

My appreciation and thanks to my advisor Dr. N.H. Carlson and Dr.
H.J. Kende for their guidance during my studies at Michigan State
University. I eXpress my deepest gratitude to Dr. D. Krauskopf for his
invaluable assistance in the preparation of this thesis.

Appreciation is also expressed to Dr. R.L. Perry and Mr. V.E.
Shull for making their expertise and laboratory facilities available
for the meristematic studies.

Thanks are also due to Dr. J.A. Nolpert and Mr. C.L. Bethke for
their assistance with the statistical analyses and computer programs.

I extend my sincere thanks to Ms. J. Grant who was reSponsible for
correcting grammar and syntax and for typing the drafts as well.

Special thanks are directed to the Agricultural Bank of Greece and
to Bodger Seeds Ltd., El Monde, California for their financial support
for my studies and the project reSpectively.

My heartfelt gratitude to my wife Rena for the many sacrifices she

had to make and also to my children George and Tonia for their love.

TABLE OF CONTENTS

Page

LIST OF TABLES ......................... vi

LIST OF FIGURES ........................ vii

INTRODUCTION .......................... 1

LITERATURE REVIEW ....................... 3

Plant Systematics ..................... 3
Cultural and Environmental Factors Related to Meristematic

Abnormalities in Marigolds and Other Ornamentals ..... 3

Temperature ....................... 3

Light .......................... 4

Growth and Developmental Effects of Ethylene ....... 5

Physiological Effects .................. 5

Morphological Effects .................. 7

l) Apical Bud Inhibition ............... 7

2) Lateral Bud Growth ................ 8

3) Induction of Roots and Root-Hairs ......... 9

4) Leaf Epinasty ................... l0

5) Imperfect Flowers ................. 11

Ethylene Antagonists ................... 12

Ethylene Synthesis Inhibitors .............. 12

Ethylene Action Inhibitors ............... 12

Environmental Factors Influencing Ethylene Production . . . 13

Temperature ....................... 13
Light .......................... 14
Water .......................... 14

iv

MATERIALS AND METHODS .....................
Introduction ........................
Experiment 1 ........................
EXperiment 2 ........................
Experiment 3 ........................
EXperiment 4 ........................
Experiment 5 ........................
Study of Meristematic Changes ...............
Analysis of the Results ..................

RESULTS ............................

Part A - Experiments 1 and 2
Role of Environmental Factors ...............

Part B — Experiments 3, 4 and 5
Role of Ethrel and STS on Abortion .............

Part C - Bud Studies ....................
DISCUSSION ..........................
APPENDICES ..........................

APPENDIX A Chemical Formula of STS ............

APPENDIX B Effect of Various Temperatures, QFD and Water
Regimes upon Moonshot Marigolds ........

APPENDIX C EXperimental values obtained for STS and
Ethrel Treatmens ................

APPENDIX D Morphological changes in apical and lateral
aborted buds ..................

BIBLIOGRAPHY ........................

Page
16
16
16
17
18
19
20
21

23

25
27

46

48
50

Table

A1

Bl

82

B3

B4

C1

C2

LIST OF TABLES

The effect of quantum flux density, temperature and
water stress on the total number of buds, apical and
lateral bud abortion in T. erecta L. cv. Moonshot . . . .

The effect of Silver Thiosulfate applications on the

total number of buds and apical and lateral bud abortion
on T. erecta L. cv. Moonshot at temperatures of 23°C

and 29°C .........................

The effect of Ethrel and Silver Thiosulfate plus Ethrel
treatments at various time combinations on T. erecta L.
cv. Moonshot at 23°C ......... . . . . . . . . . .

The effect of Silver Thiosulfate application of T. erecta
L. cv. Moonshot at 31°C .................

Formula to make Silver Thiosulfate to control bud abortion
in T. erecta L. cv. Moonshot ...............

The effect of quantum flux densities and water regimes
upon T. erecta L. cv. Moonshot at 17°C ..........

The effect of quantum flux densities and water regimes
upon T. erecta L. cv. Moonshot at 20°C ..........

The effect of quantum flux densities and water regimes
upon T. erecta L. cv. Moonshot at 23°C . .........

The effect of quantum flux densities and water regimes
upon T. erecta L. cv. Moonshot at 26°C ..........

EXperimental values obtained for Silver Thiosulfate
and two water treatments at 23 and 29°C .........

EXperimental values obtained for Ethrel and combined

Silver Thiosulfate and Ethrel treatments at various
time combinations at temperatures 23°C ..........

vi

Page

28

29

3O

41

42

43

44

45

46

47

Figure

1

Dl

LIST OF FIGURES

Graph showing the effect of temperature on total
number of buds and apical (ABA) and lateral bud (LBA)
abortion in T. erecta L. cv. Moonshot ..........

Graph showing the effect of ethrel (l00ppm) and STS
(50ppm of Silver Nitrate) at 23°C upon total number

of buds and open flowers in T. erecta L. cv. Moonshot . .

Graph showing the effect of STS (50ppm of AgNO3)
combined with ethrel (l00ppm) at 23°C on total number
of buds and open flowers in T. erecta L. cv. Moonshot . .

Morphological changes in apical and lateral aborted
buds in T. erecta L. cv. Moonshot marigolds .......

Page

33

35

37

49

INTRODUCTION

During the last two decades the bedding plant industry grew
rapidly nationwide increasing from 32.8 million dollars in wholesale
value in l959 (Carlson and Rowley, l980) to about 208 million dollars
in l98l (U.S.D.A., T982). Marigolds are one of the five leading
flowering annuals grown nationwide. There are two different Species of

marigolds, Tagetes patula L. and Tagetes erecta L. The introduction of

 

 

many dwarf African varieties has increased the demand for Tagetes
ML-

The new "Space Series" dwarf African types have a physiological
problem that manifests itself in the abortion of the terminal bud on a
significant percentage of the plants; up to twenty percent of the
apical flower buds fail to reach anthesis. It is estimated that
200,000 dollars are lost annually because of this disorder.
Preliminary experiments indicated that three environmental factors,
temperature, light and water stress influence apical bud abortion.
These environmental factors also cause terminal bud abortion in other

plant genera such as Lilium longjflorum Thumb., Chrysanthemum

 

 

 

morifolium Ram., Narcissus Sp.L., Tulipa sp.L., Iris x Hollandica cv.

 

 

Wedgwood and Rosa hybrida cv. Baccara. Leaf epinasty and adventitious

 

root formation observed in plants with aborted buds indicated possible

ethylene involvement.

Stressed plants were found to produce ethylene. Therefore the
objectives of this work were (a) to investigate the role of
temperature, light, moisture stress and ethylene on bud abortion in
Tagetes erecta L. cv. Moonshot and (b) to determine the morphological,

anatomical and physiological characteristics of this abnormality.

LITERATURE REVIEW

l. Plant Systematics and Genetics. Tagetes L. Species are among the
most important genera of commercial bedding plants. Tagetes L. Species
are included in Compositae family, subfamily Tubuliflorae, tribe

Heliantheae (Gleason and Cronquist, l963). Tagetes erecta L., also

 

known as the African marigold, is native to Mexico and Central America
and is relatively compact (30-40cm), with large flower heads (7-9cm
diam.) and conSpicuous rays. T.erecta L. has been bred extensively in
order to obtain new varieties. The diploid hybrid "Moonshot" is one of

the most important F hybrids among the "Space Age" series.

2. Cultural and Environmental Factors Related to Meristematic
Abnormalities in Marigolds and Other Ornamentals.
Temperature. Night temperatures of l3-16°C after tranSplanting with
3-5°C warmer during the day, result in a high quality crop. Carlson
and Rowley (l980) reported that lower day (l0°C) and night (8°C)
temperatures two to three weeks before flowering resulted in better
flower quality. Temperatures above 30°C during flower initiation and
the first stages of bud development inhibited normal development and
resulted in apical growth retardation and death of the apical meristem
(Armitage, l980).

Futura and Nelson (l953) found that the critical temperature for

heat delay in chrysanthemum is approximately 30°C and cultivars

sensitive to high temperatures may form "crown buds" which fail to
reach anthesis if temperatures remain above 30°C. Fluctuating day and
night temperatures are associated with "calyx splitting" in carnations
(Szendel, l938 and Holiday and Watson, l953) but Wagner and Holley
(l953) suggested that other factors may be involved. Nicols (l971)
reported that as carnation flower buds developed and reproductive
organs matured, they became more sensitive to ethylene. Buds were
also more sensitive as the temperature increased from 2 to 21°C. This
reSponse of carnation buds and open flowers to ethylene is known as
”sleepiness" and is determined by the length of the exposure and the
ethylene concentration (Crocker and Knight, l908 and Nicols, l97l).
Light, African marigolds reSpond to daylength in a quantitative
manner. T.erecta cv. Moonshot under long night (15hrs) conditions
flowers rapidly but internodes are not elongated and basal branching is
somewhat reduced. In contrast, long days delay flowering but promote
basal branching and long internodes. Marigolds are most sensitive to
photoperiod about thirty days after germination (Carpenter, l976).
Mastalerz (l965) found that flower buds of Easter lily (Lilium

longiflorum Thumb.) and bulbous iris (Iris x Hollandica cv. Wedgwood)

 

 

may stop developing and die during forcing. Bud abortion was more
severe when light intensities were low and temperatures relatively
high. At temperatures above 27°C 18 to 83 percent of the buds aborted.
This abnormality did not occur on plants held at 16°C or 27°C under
high light intensities. He suggested that the controlling factor was

the supply of photosynthates available to the developing flower bud.

Sensitivity of early flowering stages to light intensity was found
also in tomato (Kinet, l977), iris (Mae and Vonk, l974) and
bougainvillea (Hackett and Sachs, l966). Mor and Halevy (l980) showed
that low intensity lighting of young growing rose shoots promoted
flower bud development and prevented atrophy under low light
conditions. Bud development was promoted due to increased carbohydrate

translocation to the shoot tip.

3. Growth and DevelOpmental Effects of Ethylene. Ethylene triggers

 

biochemical reactions that can ultimately cause developmental changes
such as fruit ripening, abscission of leaves and flower buds,
senescence, growth (elongation of stems and roots, swelling, leaf
expansion), flowering and sex expression (Abeles, l973).

a. Physiological Effects. Ridge and Osborne (l970) and Beutelman and

 

Kende (l977) reported that increased ethylene production is related to
atrophy and breakdown of plant tissue. Apelbaum and Burg (l972)
reported that ethylene depresses DNA synthesis and cell division in
meristematic tissues. Other reports indicate that cell division and
DNA synthesis are inhibited in the root tip, stem apex and lateral buds
(Apelbaum _t__l,, l972, Kang and Burg, l973). Apelbaum and Burg (1971)
found that the polarity of cell eXpansion is also altered due to
changes in the direction of cellulose microfibril deposition at the
inner surface of the cell wall in pea. Elmer (l932), Burg and Burg

(l968), and Maxie and Crane (l968) reported that when ethylene was

applied, cell division and growth of the apex was inhibited almost

completely in buds of pea, petunia,potato and fig fruits. Holm and
Abeles (l967) observed that DNA content and growth were reduced in the
apical region of soybean seedlings eXposed to ethylene and these
changes are correlated with the mitotic index. DNA synthesis
inhibition began about two hours after ethylene was applied to
etiolated pea seedlings cv. Alaska and intensified progressively (Kang
and Burg, l973). Apelbaum and Burg (l972) suggested that ethylene
interferes with cell division by blocking a mitotic stage before
prophase in apical and lateral buds. In their eXperiments the number
of metaphase figures was reduced by 27 percent after two hours
treatment with 50 l/l ethylene, by 50 percent after Six hours and
within ten hours inhibition was almost complete.

Morgan and Gausman (l966) working with intact cotton and cowpea
plants suggested that ethylene through its effect on auxin tranSport
and synthesis may cause localized Shortages and surpluses of auxin
which contribute to the symptoms associated with the ethylene response.
Numbers of researchers (Valdovinos 35 31. l967, Ernest and Valdovinos,
l971, and Abeles, l966) reported observations indicating that ethylene
decreased levels of diffusible auxin in plant tissues through its
influence on auxin synthesis.

Ethylene inhibition of cell eXpansion and division is rapid but
the responses were observed after exposure to exogenous ethylene.
EXperiments have to be conducted to determine the exact role of
ethylene at levels comparable to those occurring naturally within the

plant.

b. Morphological Effects.

 

 

Apical Bud Inhibition. Zimmerman ££.El- (1930) first reported the
effect of ethylene on meristematic growth. Small quantities of
illuminating gas produced such responses as epinastic growth,
abscission of leaves, buds, flowers and fruits; buds "killed but still
clinging to plant"; buds stimulated to open prematurely and changes in
color in fuschia, tomato, Ageratum, potato and other plants. Two years
later Hitchcock et 31. (l932) observed that young flower buds of lily,
narcissus and tulip were killed by illuminating gas containing four
percent ethylene at concentrations of l to 10,000ppm or higher. In
some cases lower concentrations killed the flower buds, particularly in
lily.

Chemical compounds capable of releasing ethylene such as
(2-chloroethyl)phOSphonic acid (ethephon, ethrel), provide a means of
inducing ethylene responses under field conditions. Andersen working
on peas in l970 and l976 found that ethephon could break apical
dominance. He suggested that this effect was due to the release of
ethylene within the plants and subsequent ethylene interference either
with auxin transport (Morgan and Gausman, l966) or nutrient supply to
the inhibited buds. Andersen believed that the effect of ethephon on
apical dominance was dependent on the nutritional status of the plant.
If enough carbohydrate was present due to high rates of photosynthesis,
ethephon treatment diverted growth activity from the apex to the

lateral buds.

Burg and Burg (l968) studying the effect of ethylene on bud
develOpment in pea seedlings found that low concentrations of applied
ethylene were highly effective in retarding bud development. Ethylene
concentrations of 0.2 and 2.0 ppm half inhibited and completely
suppressed the growth of buds on nodal sections. Low concentrations of
ethylene (1 ppm) were also found to prevent the opening of immature
carnation buds (Mastalerz, l977). Zieslin and Halevy (l976c) reported
that applications of ethylene producing compounds markedly increased
flower bud atrophy in Baccara roses.

Lateral Bud Growth. Yeang and Hillman (l981) suggested that the

 

promotion of axillary bud development by ethylene action on the apical
shoot was associated with the availability of diffusible ethylene in
the tissues of the treated shoot. Ethephon stimulated axillary bud
growth when applied to the apical shoot in bean, but was ineffective
when applied directly to the axillary bud. It seems that a simple
stimulatory effect of ethylene on bud development does not occur. It
has been shown that ethylene inhibits cell division in apical meristems
(Apelbaum gt 31., l972) evidently by inhibition of DNA synthesis (Kang
and Burg, l973). The reduced activity of the apical meristem may also
lead to diminished auxin synthesis (Ernest and Valdovinos, T971)
compounded by ethylene inhibition of auxin transport (Morgan and
Gausman, l966). The effect on lateral buds should be similar.
According to Weaver gt 31. (l972), ethylene accumulates in the apical
regions no matter where it is applied, moving with photosynthate, thus

if no or little photosynthate transport takes place, ethylene is

presumably not transported either. Retardation of apical shoot growth
was always observed when ethylene or ethepon was applied or when the
apical shoot was physically constricted (Yeang and Hillman, l981),
therefore inhibition of apical growth could be the main cause of
lateral bud growth. When the apical bud is inhibited nutrients and
other growth factors are directed to the lateral buds, so that lateral
bud growth subsequently occurs.

Induction of Roots and Root-Hairs. Root initiation from leaves, stems,
flower stems and preexisting roots in a variety of plants can be
induced by ethylene. The phenomenon has been observed by a number of
investigators but the most thorough survey was completed by Boyce
Thomson Institute investigators in the early 1930's (Zimmerman and
Hitchcock, l933, Zimmerman gt al. l930 and l933, Zimmerman and
Wilcoxon, l935). Working with 202 different varieties of plants they
found that roots were initiated by ethylene and its analogs CO
(Zimmerman gt 31, l933), acetylene and propylene (Zimmerman and
Hitchcock, l933). Roots are formed on the region of stem elongation in
tobacco and hydrangea; over the whole stem in coleus, tomato and
marigold or at nodes in cosmos. Rooting from leaves of tomato and
heliotrope was also induced by ethylene. When varieties of Tagetes
egggtg L. were treated with various concentrations of ethylene or its
analogs, roots appeared first near the base, then further up the stem.
Additional ethylene treatments induced secondary roots from

adventitious roots. During the last two decades a number of

IO

investigators (Chadwick and Burg, l967 and Abeles, l973) have observed
the formation of root hairs due to ethylene treatments on plants such

as Pisum sativum, Vicia Faba L., Sinapis alba, Cheiranthus cheiri and

 

 

 

Raphanus sativa.

 

Apelbaum and Burg (l972) suggested that the phenomenon of
adventitious root formation may be due to ethylene irreversibly
inhibiting polar auxin transport. Ethephon or ethrel increased rooting
in fifteen herbaceous species and some woody plants such as apple and
blueberry (Cummins and Fiorino, l969, Kender gt_al., l969).

Leaf Epinasty. One of the most rapid and visible reSponses of tomato,

 

sunflower and marigold (T.erecta L. and T.patula L.) to ethylene is the
downward growth of the petioles known as epinasty. Early in l9l7 Doupt
reported a "definite striking and not easily mistaken" response of
tomato, Salvia and Hibiscus plants to illuminating gas. Leaf
abscission, epinasty of petioles and tissue proliferation were
observed. The epinastic reSponse was primarily a sharp bending
downward of the leaflets at the base and a ventral inrolling of the
edges of the leaflets. This was a result of a rapid expansion of the
cells in the upper side of the petiole rather than those in the lower
side, due to the inhibition of lateral auxin transport to the lower
side of the petiole (Lyon, l970). Epinasty was observed in 89 of 202
different species and cultivars tested by Crocker gt 31. in l932.

T.erecta L. and T.patula L. showed marked epinasty of the leaves.

 

Young leaves curved along the whole length of the petioles, while

11

older leaf petioles bent near the stem. Older leaves showed only a
slight degree of recovery. Gilbert and Sink (l970) observed similar
reSponseS in a number of plants. Saltveit gt al. (l979) found that
mechanically bent petioles of poinsettia plants produced three to
seventy times more ethylene than petioles from unstressed plants.
Exposure of potted poinsettia plants to l0 ppm ethylene in air produced
the same pattern of epinasty in four hours as was produced by 24 hours
of mechanical stress.

Abeles (l973) reported that the minimum amount of ethylene
required to cause epinasty varied between 0.01 ppm for African
marigolds to 0.1 ppm for tomatoes. The response is Specific for
ethylene or its analogs, is sensitive to low concentrations, occurs
rapidly and requires little in the way of experimental setup to
observe; therefore epinasty is a useful bioassay for ethylene
detection.

Direct involvement of ethylene in inducing epinasty has been
suggested by Beyer (l976) and Sacalis J.N. (1978) since silver nitrate
(AgN03) reduced the reSponse, perhaps due to the antagonistic role of
Ag+ to ethylene action (Beyer, l976 and Saltveit gt 31., T978).

Imperfect Flowers. The formation of imperfect flowers was observed

 

in a number of floriculture crops. According to Mastalerz (l977)
formation of imperfect flowers is genetically controlled, but
variations in air temperature, light, water and air pollutants, i.e.
ethylene and its analogs could be associated with the development of
imperfect flowers on mums, (Miller and Kiplinger, l962 and Cox, l969)

roses and carnations.

12

4. Ethylene Antagonists.

 

Ethylene Synthesis Inhibitors. Ethylene production can be suppressed

 

by inhibitors which block certain reactions during ethylene
biosynthesis such as aminoethoxyvinylglycine (AVG) and aminooxyacetic
acid (ADA). These chemicals suppress the synthesis of the natural
precursor of ethylene, 1-aminocycl0propane-l-carboxylic acid (ACC).
Ethylene production may also be inhibited by factors which interfere
directly with conversion of ACC to ethylene such as 2,4-dinitrophenol
(DNP), C02 and high temperatures (Yang, l980).

Ethylene Action Inhibitors. Beyer (l976) showed that Ag+ inhibits
ethylene action. This has been confirmed by a number of researchers
(Beutelmann and Kende, l977, Halevy and Kofranek, l977, and Saltveit gt
31., l978. Silver ion (Ag+) applied as its nitrate salt

(AgN03) effectively prevents the classical "triple" reSponse in

intact etiolated pea plants, senescense in orchid plants (Beyer, l976a)
and epinasty in tomato plants (Beyer, l976b). The inability of applied
ethylene to elicit normal ripening in silver treated tissue of apple,
tomato and banana fruits suggests that Ag+ interferes with an

early and initial critical step in ethylene action in the ripening
sequence (Saltveit gt 31., l978).

The usefulness of AgNO3 is somewhat limited by its immobility
within plant tissue and by its phytotoxicity at high concentrations.
Despite this and the fact that the mode of Ag+ action is unknown,

Beyer (l976a) and Yeang and Hillman (l98l) suggested that AgNO3

may be a useful tool to investigate various aspects of growth such as

l3

meristematic inhibition, adventitious root formation and leaf epinasty.

Veen and Van de Geijn (l978) discovered that silver nitrate
complexed with thiosulfate was extremely mobile within the plant and
very efficient in extending vase life of cut carnations since complexed
silver remains active within the tissue for an extended period. Use of
silver thiosulfate (STS) applied as Spray to foliage or buds
significantly reduced petal, bud and flower abscission in Geranium,
Zygocactus, Calceolaria and Bougainvillea by blocking ethylene action
for a period of twenty-one to twenty-eight days (Miranda, l980, Reid
.E£.El-9 l980, Cammeron and Reid, l983 in press). Silver thiosulfate
treatments also markedly extended shelf and vase life of carnation,
Gypsophila and Gladiolus flowers when applied up to three days before
cutting. Silver thiosulfate can also prevent premature wilting of
plants induced by ethylene (Farhoomand gt 31., l980, Halevy and Mayak,
l98l, Mor gt al., l980, Nicols_gtial., l982).

5. Environmental Factors Influencing Ethylene Production.

 

Temperature. Temperature greatly influences ethylene production, the
Optimum being about 30°C. As temperature rises above 30°C the rate of
production falls gradually until ethylene evolution ceases at 40°C
(Burg l962, Abeles, l973). Field (l981) reported that a rise in
temperature from 25 to 35-37.5°C approximately doubled the rate of

ethylene production in bean (Phaseolus vulgaris L.) leaves. Ethylene

 

production declined rapidly above 37.5°C which suggested a loss of
integrity in the ethylene synthesizing system. Similar results were

observed by Saltveit and Dilley (l978) in eXperiments on excised

14

segments of etiolated pea plants (Pisum sativum).

ng_t. Ethylene production can be regulated by light. Depending on
the tissue involved, light can increase or decrease the rate of
ethylene production which may mediate effects formerly attributed
solely to light. Andersen (l976) found that inhibition of pea apical
buds and maximal growth of laterals was obtained with high irradiance.
Subsequent ethephon treatments of young plants resulted in lateral
growth but the growth was significant only when apical dominance was
already weakened by high irradiance and/or CO. Changes in ethylene
production in the two upper shoots of rose plants were measured as
affected by decreasing temperature and high light intensities, factors
which encourage flower atrophy (Zieslin and Halevy, l976). Ethylene
production was much higher under conditions of full light than under
fifty percent shade.

Annon (l977) reported that blue plus far-red (B/FR) caused a rapid
rise in ethylene evolution from peach apices. A higher endogenous
ethylene content was also found under B/FR relative to blue and shade
conditions.

Water. Andersen (l976) found that waterlogged plants have reduced
apical dominance and plants under drought conditions exhibit strong
apical dominance. Kawase (l972) proposed the involvement of ethylene
in apical dominance since waterlogging often gives rise to endogenous
ethylene production. Studies on a variety of horticultural plants such
as tomato (Lycopersicon esculentum Mill.), marigolds (T.patula,

T.erecta) and broad beans (Vicia Faba L.) revealed that the level of

 

15

ethylene in waterlogged plants exceeded those in control plants (El-
Beltagy and Hall, l974, Jackson and Cambell, l975, Kawase, l972) as the
result of at least two processes (a) anaerobic stimulation of ethylene
production and (b) the "water jacket effect" preventing ethylene

diffusion out of the roots (Bradford and Yang, l981).

MATERIALS AND METHODS

Five experiments were conducted on apical bud abortion in
T.erecta L. cv. Moonshot. The first two investigated the effect of
temperature, light and moisture. Their results led to the design of
three other experiments investigating the effect of ethylene and
ethylene antagonists on bud abortion. For each experiment, seeds of
T.erecta L. cv. Moonshot were germinated at 26-28°C under mist in
plastic flats. Seven days before tranSplanting, the flats were moved
from the mist bench into a greenhouse environment (20°C Day and l4°C
Night 12°C). Transplanted plants were grown in a peat-lite medium in
8.75cm plastic cells and fertilized with 20 N -8.7 P -7.7 K, providing
200 ppm N at each irrigation. Plants in experiments four and five were
leached with tap water every fifth watering.

For the first four experiments the following parameters were
recorded: time to reach visible bud (diam.>2mm), days to flower from
sowing, flower diameter (cm), total number of buds (diam.>5mm), apical
and lateral bud abortion, vegetative height (cm) and total plant height
measured from the media line to the uppermost leaf held parallel to the
soil and to the top of the uppermost fully open flower reSpectively.

Experiment l. The objective of the first experiment was to evaluate

 

the effect of different quantum flux densities (QFD) and low
temperatures on bud abortion on T.erecta cv. Moonshot. Fourteen days

after sowing, the seedlings were tranSplanted and placed in growth

16

17

chambers at l7°C Day and l4°C Night (12°C) and QFD of 50, l00, l50, 200

and 300u Em.2 ’25'1

S'1 (:20 “Em ). Cool white flourescent lamps
were used as the light source. Water was applied between 9:00 and
l0:00 a.m. after 24, 48 and 72 hr. depending Upon treatment.

A split-plot experimental design with five main plots with six
plants for each sub-plot per block was used. There were three

replications. The experimental design was:

 

A - 5012011 Em'zs'l
Main Plots 8 - l00120 "
5 Light Levels C - l50120 "
D - 200120 "
E - 300:20 "
Sub-Plots A - l00 ml/24 hours
3 Water Levels B - lOO ml/48 hours
C - 100 ml/72 hours

EXperiment 2. The objectives were to evaluate the effects of higher
temperatures in relation to different QFD and water regimes on apical
bud abortion.

A derivative of the split-plot design, the split, split plot with
three replications was used for the experiment with six plants for each

sub-sub plot per replication. The design was as follows:

18

 

 

Main Plots A - (20°C Day, l6°C Night) ,:2°C
3 Temperature Levels 8 - (23°C " , l9°C " ) .:2°C
C _ (26°C It , 22°C u ) :20C
-2 -l
Sub Plots A - 250:2011Em s
3 Light Levels 3 - 300:20 "
C - 350120 "
Sub,Sub Plots A - l00 ml/24 hours
3 Water Levels 8 - lOO ml/48 hours

C - 100 ml/72 hours

Experiment 3. The third experiment was conducted under greenhouse

 

conditions and the objective was to study the effect of Silver
Thiosulfate (STS) applications on apical bud abortion.

Seeds of T.erecta cv. Moonshot were germinated under mist.
Fourteen days before transplanting, the flats were removed from the
mist bench into a greenhouse environment. Twenty-one days after
sowing, the seedlings were transplanted and placed under appropriate
temperatures. Water application was done between 9:00 and lO:OOa.m.
after 24 and 48 hour intervals with 200 and 100ml of water
respectively. Plants were treated with Silver Thiosulfate (STS) at
50 ppm of Silver Nitrate in Sodium Thiosulfate (Table A1). Control
plants were Sprayed with deionized water. In all cases ten ml of STS
or water were Sprayed per plant with a hand sprayer. Tween 20(0.l%)
was added as a surfactant to the STS treatments. All applications were

done at first visible bud stage (diam>2mm) between 5:00 and 6:00 p.m.

19

The next watering was after a minimum of 24 hours.
A split, split plot design with three replications was used for
the experiment with Six plants within each sub plot. The design

configuration was as follows:

 

Main Plots A - 23°C Day, l9°C Night .:2°C

2 Temperature Levels B - 29°C Day, 25°C Night ‘:2°C
Sub Plots A - 200 ml/24 hours
2 Water Levels B - 100 ml/48 hours

Sub,Sub Plots

2D
I

+ STS (50ppm AgNO3) lOml/plant

 

STS B

- STS (Deionized I120) anl/plant

Experiment 4. The objective of the fourth eXperiment was to determine

 

the effect of exogenous ethylene applied as (2-chloroethyl)phOSphonic
acid (ethephon), alone or in conjunction with silver thiosulfate (STS)
upon apical bud abortion.

Greenhouse temperatures were 23 Day and l7 Night(:2°C). Water was
applied between 8:00-9:00a.m. and 5:00-6:00p.m. according to plant
requirement. One hundred ppm ethrel (A.I. 21.3% ethephon) and 50 ppm
of Silver Nitrate in Sodium Thiosulfate (Table A1) were applied as a
Spray to run off. Control plants were Sprayed with deionized water.
Tween 20 (0.1%) was used as a surfactant in all ethrel and STS Sprays.
All applications were done at the first visible bud stage (diam.>2mm).

Plants were watered after a minimum of 24 hours.

20

A completely randomized design with four replications and six

plants per replication was used. The design configuration was as

 

 

follows:
2 chemicals A - Ethrel (l00ppm) lOml/plant
B - STS(50ppm)+Ethrel (l00ppm) 2x10ml/plant
Application time
(base time 0)
STS Ethrel
A - Control (deionized H O) - -
B - Ethrel (l00ppm) - O
and 7 application C - STS(50ppm)+Ethrel(l00ppm) 0 0
time combinations D - " " - 3 0
E - " “ - 6 0
F - " " -12 0
G - " " -24 0

Experiment 5. The last eXperiment was conducted to determine if high

 

temperature effects can be offset by application of silver thiosulfate.
Cultural procedures were the same as previously described except that
the plants were placed in a growth chamber at appropriate treatment
combinations after transplanting. Environmental conditions were 31
'25'1.

11°C constant and QFD 400:20L1Em Cool white flourescent

lamps were the light source for a nine hour photoperiod.

21

Silver thiosulfate was applied at 50 ppm of AgNO3 (Table A1) during the
week before the first apical bud was observed and one and two weeks
later. Ten ml of solution were applied to the foliage with a hand
Sprayer. Control plants were Sprayed with deionized water. Tween 20
(0.1%) was used as a surfactant in silver thiosulfate treatments.
Applications were made just before the dark period. Water was applied
after 24 hours.

A completely randomized design with four replications and six

plants per replication was used. The experimental configuration was as

follows:
2 substances A - (+STS, 50ppm of AgNO3) l0ml/plant
B - (-STS, deionized H20) l0ml/plant
A - Control (+1 week from visible bud)
and 4 application 8 - STS (-1 week " " " )
time C - STS (+1 week " " " )
D - STS (+2 week " " " )

The following parameters were recorded: time to reach visible bud
stage (diam>2mm), days to flower from sowing, days from visible bud to

flower and number of apical bud abortions.

Study of Meristematic Changes. A study was conducted of meristematic
changes in plants from experiments two and four. Terminal and lateral

buds of randomly chosen plants in all treatments were collected at

22

weekly intervals from visible bud to experiment termination. Buds were
collected and immediately fixed in FAA (50% ethyl-alcohol, 10%
formaldehyde, 5% glacial acetic acid and 35% water). The samples were
dehydrated with tertiary butyl-alcohol and infiltrated with paraplast
(Johansen, 1940). Each bud was imbedded in paraplast and mounted on
plastic frames. Ten micron sections were cut and fixed on slides with
Haupts adhesive and 10% formaldehyde solution. The sections were
stained with Safranin and Fast Green as described by Berlyn and Miksche

(1976) and Sass (1958).

Analysis of the Results. The result section is divided into three
parts. The first two give results of the experiments performed, while

part three deals with the anatomical studies.

RESULTS

The objectives of the first two experiments were to investigate
the role of temperature (17, 20, 23 and 26°C), quantum flux densities
(50, 100, 150, 200, 250, 300 and 35011Enrzs’I) and water regimes (high,
optimum and low) Upon apical bud abortion. Experiments three, four and
five provided data pertinent to the prevention of this disorder by
foliar applications of silver thiosulfate (STS). The morphological,
physiological and anatomical changes that occurred during apical bud

abortion are presented in the last part of this section.

1. Experiments 1 and 2. Complete data are presented in Appendix B.

 

Days to First Bud. Plants grown in temperatures greater than 20°C and
1

 

quantum flux densities above 200,,Emrzs' or under natural light,
reached the first bud stage four to six weeks earlier than plants grown
below 200 uEnFZS", depending on water stress. Quantum flux densities
less than 200,,Em'zs'l and temperatures lower than 20°C delayed the
appearance and thereafter strongly inhibited the development of the
first bud. The lower the light intensity the greater the inhibition

regardless of water treatment.

Days to First Flower. Plants grown under quantum flux densities below

 

ZOOuEm'zs'I did not flower. As quantum flux densities increased above
200 uEm'zs'I and temperatures increased from 17 to 26°C, plants
flowered more rapidly. Plants under low water treatments flowered

earlier than plants under regular watering and high water stress.

23

24

Flower Diameter. Flower diameter was measured when the first flower

 

was fully expanded. Temperature and water treatments had a significant
effect on the size of the first flower. The result was larger flowers
compared to the controls.

Vegetative and Total Height. Increasing temperatures, quantum flux
densities and low water stress in all experiments increased vegetative
and total plant height.

Total Number of Buds. Quantum flux densities higher than 250 “Em—2 s"

 

and temperatures above 20°C did not have an effect on bud count (Fig.
1). Temperatures of 17°C and light intensities below 200MEm‘2 s"
significantly reduced total bud number (Table 1).

Apical and Lateral Bud Abortion. Apical and lateral bud abortion did
not occur when plants were grown at temperatures of 17 and 20°C
regardless of light and water treatments (Table 1). Temperatures above
23°C significantly enhanced lateral bud abortion and above 26°C both

apical and lateral bud abortion (Fig.1).

Leaf Epinasty. Epinasty was observed in plants at temperatures higher

 

than 26°C. The apical bud subsequently aborted on these plants.
Epinasty and increased apical and lateral bud abortion was also
observed in plants placed under greenhouse conditions (temp>30°C and
QFD>1500uEm"2 s") after termination of the experiments.

Adventitious Root Formation. Adventitious root formation occurred in
low moisture stress plants under high temperatures (>26°C). Single
root hairs were formed from epidermal cells along the lowest three
internodes. The density and size of the roots were reduced from the

lowest to the third internode.

25

Imperfect Flowers. A number of plants in temperatures above 26°C had

 

small, single flowers (diam<30mm) and a partially developed flower
corolla. The rest of the flower failed to develop and decayed.
Imperfect flowers occurred in plants where apical and lateral bud

abortion were also observed.

2. EXperiments 3, 4 and 5. Complete data are presented in Appendix C.

 

Days to First Flower. Ethrel applications significantly delayed

 

flowering, but applications of silver thiosulfate (STS) alone or in
conjunction with ethrel had no effect on flowering when applied at or a
week before visible bud (Table 4).

Total Number and Diameter of Open Flowers. Plants treated with ethrel

 

alone had a significantly smaller number of fully open flowers and a
significant reduction in flower size compared to control or silver
thiosulfate treated plants. Total number of flowers and flower
diameter was not significantly different from control in STS treated
plants, even those treated with ethrel (Fig. 2 and 3).

Growth After Ethrel and STS Applications. Ethrel alone or in
combination with Silver thiosulfate resulted in taller plants than the
controls. Plants treated with silver thiosulfate alone were shorter
than untreated plants.

Total Number of Buds. Plants treated solely with ethrel had a

 

significantly higher number of buds than controls and plants Sprayed
with silver thiosulfate and ethrel under other time combinations (Table

2 and 3). Silver thiosulfate applications at temperatures above 23°C

26

(Fig. 2 and 3) and water stress conditions did not significantly affect
the total number of buds.

Apical and Lateral Bud Abortion. All apical buds on plants treated

 

solely with ethrel aborted. Silver thiosulfate prevented abortion of
apical and lateral buds for at least four weeks regardless of time of
its application prior to ethrel treatment (exper.4) or temperature and
time treatments (exper.3 and 5, tables 2 and 3).

Leaf Epinasty. Epinasty was very characteristic of ethrel treated

 

plants and appeared within four hours after application. In older
leaves, the epinastic response was permanent while younger ones
gradually recovered. Plants Sprayed with silver thiosulfate alone or
prior to ethrel applications did not Show epinasty.

Adventitious Root Formation. Adventitious roots were initiated over

 

the whole stem on all ethrel-treated plants. Roots were formed from
the epidermal cells along the whole length of the stem. Their density
and size was the same along the stem and they started scenescing two to
three weeks after initiation. No root formation was observed in plants
where silver thiosulfate was applied alone or prior to ethrel
treatment.

Imperfect Flowers. Plants treated with ethrel had a number of smaller

 

flowers and other abnormalities such as partially developed corolla.
These abnormalities were not observed on plants treated with silver

thiosulfate for at least three weeks after application.

27

3. Bud Studies. Sections of T.erecta cv. Moonshot buds examined unde

 

microscope showed that aborted buds were more mature than non-aborted
of the same age and size. Development of mature pollen was observed in
both ray and disk flowers. Marginal florets were the most mature.
Abnormalities such as cell wall breakage or formation of a separation
layer at the region where florets are attached to the receptacle were
not observed. Cell disorganization and an irregular breakage of the
cortex, vascular tissue and pith was observed where the receptacle is
attached to the stem. These zones were not typical abscission zones
because they appeared as region of abrupt structural weakness

(Appendix D).

28

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29

 

 

 

 

 

 

Table 2. The Effect of Silver Thiosulfate Applications on the Total
Number of Buds and Apical and Lateral Bud Abortion of
T. erecta L. cv. Moonshot at Temperatures of 23 and 29°C.
Total Number Apical Buds Lateral Buds
of Buds (1) Aborted (1) Aborted (1)
Temperature 5_T_§ '12 £5. E E STE §T_5 fl 5_T§
23°C 4.5 5.4 0.0 0.0 0.5 0.7
29°C 5.0 6.0 0.0 0.0 1.0 1.5
Significance:
Temperature NS NS *
Treatment NS NS *
(I) Mean separation within treatments by HSD (.05)test. Values:

Lateral buds aborted = 1.2.

30

 

 

 

 

 

 

Table 3. Effect of Ethrel and Silver Thiosulfate Plus Ethrel
Treatments at Various Time Combinations (1) on T.erecta L.
cv. Moonshot at 23°C.

Total Apical Lateral Total
number buds buds Number

Treatments of buds aborted (%) aborted (%) of flowers

1. Control 13.3 0 0 5.8

2. Ethrel 22.1 100 O 3.0

3. STS+Ethrel 16.5 0 0 5.6

4. " " 15.5 0 O 5.4

5. " " 18.1 0 O 4.7

6. " " 16.1 0 0 3.3

7. " " 20.4 0 O 3.4

Significance

Treatment ** ** *

(1)

(2)
(3)

All ethrel applications (lOOppm) at zero (0) time.
applied at 0, -3, -6, -12 and -24 hrs.

Data was taken 28 days after Ethrel applications.
Mean separation within columns by H30 (.01).
5.7; total number of flowers = 3.2.

NS = Non significant; *

= significant at 5% level; ** -

significant at 1% level.

50 ppm of STS

Total number of buds

31

Table 4. Effect of Silver Thiosulfate Application on T.erecta L. cv.
Moonshot at 31°C.

 

 

 

Days to Days to Days from Apical
visible flower visible bud buds
Treatments bud (V8) to flower aborted
1. Control 40.9 63.8 23.0 0.1
2. STS '
(1 wk before VB) 42.9 64.7 21.7 0
3. STS
(wk of VB) 38.9 60.5 21.6 0
4. STS
(1 wk after VB) 36.4 56.3 19.9 0
Significance
Treatment ** NS *

(1) Mean separation within columns by H50 (.05) test.
Values: Days to flower = 5.48, NS = Non significant; * = significant
at 5% level; ** = significant at 1% level.

32

Figure 1. The effect of temperature on total number of buds
and apical (ABA) and lateral bud (LBA) abortion in

T. erecta L. cv. Moonshot.

Number

33

"SOLO 1 I 7.2

 

 

3.2
I
1.8 Lateral bade
1.1 aborted
I
1.06
Apical
0.2 0.2 bode
I 034 3'07 ; - a CM“
20 23 26

Temperature (C)

34

Figure 2. The effect of ethrel (100 ppm) and STS (50 ppm of AgNO3 )
at 23°C upon total number of buds and open flowers in

T. erecta L. cv. Moonshot.

Number of bude and tlowere

 

 

31's plua
Ethrel

Figure 3.

36

The effect of STS (50 ppm of AgN013) single and combined
with ethrel (100 ppm) at 23°C on total number of buds and
open flowers in T. erecta L. cv. Moonshot. Time of STS
application -24, -12, -6, -3 and 0 hours prior to Ethrel

application (time 0).

ilowere

oi bude and

Number

37

 

 

25
HSD(.05)
20.4
20 Bud.
18.1
A/O
15 “-1 1” 115.5
5.7
10
Flowere
5 ./ 5,4 ‘5.e
. ‘/ ‘.7
3.2 3" ‘3-3
0

Time of STS application (hour-a)
prior to Ethrel application (time 0)

DISCUSSION

As temperature increased from 23 to 31°C bud abortion in I;
ggggtg L. cv. Moonshot increased. This confirms the work of Armitage
(1980) Showing temperatures above 30°C result in death of the flower
bud in Tagetes patula L. Temperatures between 25 and 35-37.5°C greatly

 

increase endogenous ethylene production in plants (Field, 1981 and
Salveit and Dilley, 1978).

A known anti-ethylene agent, silver ion, totally prevented bud
abortion in plants under environmental conditions favoring ethylene
synthesis and in the presence of ethrel, an ethylene releasing
compound. This inhibition of bud abortion by STS in marigolds supports
the hypothesis that silver ion (Ag+) is an inhibitor of ethylene action
rather than ethylene synthesis (Beyer, 1976, Veen, 1979, Miranda, 198;.
Cameron and Reid, 1981 and 1983).

The maturity of aborted buds also indicates the involvement of
ethylene in this abnormality. The ability of ethylene to promote
maturity is well established. ReSpiration and premature fading of buds
in certain ornamental plants was found to be accelerated by both
ethylene and pollination (Abeles, 1973, DeMunk, 1972). According to
Mayak and Halevy (1980) pollination induced the onset of the second
phase of ethylene production which is characterized by an accelerated

rise of ethylene synthesis.

38

 

39

Cell disorganization and irregular breakage of the vascular tissue
of the aborted buds where the receptacle is attached to the stem tip
can also be attributed to ethylene action. According to Webster (1968)
these areas in bean are considered an abscission layer. Breakage of
the cortex, vascular tissue and pith was present in both mature and
immature aborted buds. Therefore, there may be two sites of ethylene
action; one in the region where the bud receptacle and the stem tip
are attached and the other within the bud.

The abortion of all apical buds in plants treated with ethrel and
the subsequent accelerated outgrowth of laterals supports the
hypothesis that ethylene accumulating in the apical regions moved with
photosynthates (Weaver gt 31. 1972). When active apical buds are
present, there is little photosynthate transport to lateral sites.

When retardation of the apical bud occurred, nutrients and other growth
factors were redirected to the laterals and subsequent growth occurred
(Andersen, 1976, and Yeang and Hillman, l981).

Leaf epinasty and adventitious root formation observed in plants
with aborted buds can also be attributed to ethylene action. Similar
results were observed by a number of investigators (Zimmerman and
Hitchock, l933, Zimmerman gt_al., 1930 and 1933, Zimmerman and
Wilcoxon, 1935) when I;_g§ggta L. plants were treated with ethylene.

Silver thiosulfate totally inhibited leaf epinasty and adventitious

4O

root formation in the presence of ethrel or environmental conditions
favoring ethylene synthesis and action. On the other hand the
formation of smaller and in some cases imperfect flowers could not be
attributed soley to ethylene action because other factors such as
genetic control and variations in environmental conditions may be
involved.

From the results of these eXperiments we propose that unfavorable
environmental conditions such as temperatures above 23°C trigger
endogenous ethylene production. Ethylene accelerates maturity of the
apical bud which ceases its development and finally aborts. The
abortion of the apical bud results in an outgrowth of laterals which
subsequently show the same abortion symptoms. Silver thiosulfate
applied at 50 ppm of Silver Nitrate in Sodium Thiosulfate in early
stages of bud development totally prevented bud abortion in T. erecta
L. cv. Moonshot in the presence of ethrel or environmental conditions
favoring ethylene synthesis and action. The use of silver thiosulfate
seems commercially promising because STS at low concentrations is not
phytotoxic and minimizes cost. Further work is needed to investigate
possible side-effects of STS use and the potentiality of other

compounds to prevent this abnormality.

APPENDICES

 

APPENDIX A

41

Table A1. Formula used to make the Silver Thiosulfate to control

bud abortion in T. erecta L. cv. Moonshot (Miranda, 1980).

1. 50mg Silver Nitrate (AgNO3) dissolved in 1/2 liter of distilled
water.

2. 292mg of Sodium Thiosulfate (NaZSZO .SHZO) dissolved in 1/2

3
liter of distilled water.

3. The Silver Nitrate (AgN03) solution was mixed in the Sodium

Thiosulfate (Na2520 .5H20) solution slowly under continuous

3
stirring.

4. 10ml STS solution was Sprayed per plant.

APPENDIX B

42

 

 

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a.mH o.HH a.m N.o N.“ m.m o.mm m.mm I :
N.NH m.NH ~.N F.o O.“ o.m m.om “.mm o _-m -Em omm
o.mH m.IH m.m H.o N.m m.m m.mm H.~¢ I

a.mH e.oH m.m m.o N.m o.m ~.Hm c.am I :
m.mH m.HH N.m N.o ¢.m m.m “.mm m.oe o _-m~-Em oom
o.mH H.MH m.~ o.o N.m m.m m.mm ~.ee I

m.om m.mH o.m H.o o.m o.o H.Hm H.~I I :
H.mm m.~H m.m H.o m.u H.w w.mu “.mm o .-m~-sm 0mm
o.¢m m.o~ o.m m.o N.m m.m ~.Im a.mm I

“563 made Imbcona Imogene mesa Aggy III cape: HIIII

“Im_mI “Imwmg mung muss Longs: .smwu Imxo_e mpnwmw> AHV

_muoh m>wuwummm> _mgmum4 .mowa< Fmpop Logo—I ob mama o“ mama acmEpmmc»

 

.uomm um aosmcooz .>u muumgm .H cog: moswmmm Imam: new mmwp_mcmo x:_I Ezpcmac mo Homwmm mg» .Im mFQIF

APPENDIX C

46

:04 n I .Ime u I “Hv

 

 

m.~ H.N N.H N.o m.m o._ H.@ o.m ”Amo.v omI
o.Im m.mH m.H o.o N.o H.m ~.mm a.mo I
mpm oz
a.mm a.mm m.H o.o m.m m.m o.NoH m.m~ I
m.¢~ m.~H o.H o.o m.m o.m a.mm m.om I
mpm
m.om m.mH H.H o.o N.¢ m.o m.moH m.mm I comm
H.~N H.om H.H o.o m.m H.~ “.mm a.mo I
mpm oz
m.om m.cm v.0 o.o o.m N.m «.mm a.mo I
“.mm N.NH m.o o.o m.m c.m ~.eoH m.HN I
mhm
a.mm H.mH m.o o.o ~.m m.o m.eoH m.o~ I oomm
AEUV “Euv umuconm nmuconm moan AEUV can Imam: .Ewcu .nsmh
uIm_mI uImwaI mean moan Lamas: .Eaeo Imzo_c m_n_mw> aflv
Peach m>wumummm> chmumI Pmuwa< pagop cszFI ou mAII o» mx~o ucmsummcp

 

.UomN Ucm MN um mucmEumeh Lmumz 03H Dcw mucuzzmowrz. Lm>:.m Low bmcwwuno mm:_.m> FMHCmeLmme .HU m—nmh.

 

 

.mcowumuw_qam mpm cmumo mxmu ucmwm aucmzu cmum:_scmu mm: wumo Amv
.a_m>wuuwammg I new I .m .e .m mucmEummcu
qu IOI mLIOI am. new NH- .I- .m- .o me_u um Im__aam mew .ms_p on oemN Be m=o_ueu__aam PmLIum .PI ANS
.2aa om “a mcm new gun oo_ pm Im__aaa mm; _mchm AHV
m.I ~.m m._ ~.N o.m ”fifio.v omI
I.m a.mm m.mm o.Hm o o I.om m.~ o.Hm m.mm = = .m
m.m «.mm o.Nm N.om o o a.mfi H.~ ~.mm “.mm = = .o
N.I o.m~ o.mm I.om o o H.mH I.~ H.am m.om = = .m
I.m m.- m.oe m.mm o o m.mH I.N a.mm N.mm = = .I
o.m o.- N.mm m.om o o m.oH N.k o.mm I.Im ngguw+mhm .m
7
.4 o.m a.mm fl.am H.0m o oo_ H.NN ,.I m.ma m.~m _aIIum .N
m.m ~.o~ o.mm N.mm o o m.mH o.m a.mm N.em Pocucoo ._
ARV ARV
“Luzopw mo .uwpaam AEUV AEUV umugonm umugonm moan mo AEUV nan
ImaEII cmuwm HIm_mI uzmvms mvan mean Lungs: .Ew_n Logo—m «PIPMw> mucmEHImch
Peach R.Lm .mm> Pouch m>_umummm> _mcmum4 Pmuwa< Pouch chOFI op mxoo op mxmo Amy

.uomm mmgaumgmasme um mcowumcwnsou mewp mzowgm>

um mucmsummgp _mLIum new mummpzmowIp Lm>_wm umcwnsou new _mIIam Low cmcwmuao mm:_m> Foucmewcmaxm .Nu mFQIP

A_V

APPENDIX D

Figure 01.

48

Morphological changes in apical and lateral

aborted buds in T. erecta L. cv. Moonshot.

a. Mature pollen grain in aborted buds (60x).

b. Normal vascular tissue and cells in non-aborted
buds (60x).

c. Cell disorganization and irregular breakage
of vascular tissue at the region where the
receptacle attaches to the stem in aborted
buds (60x).

d. Cell disorganization and irregular breakage
of vascular tissue at the region where the
receptacle attaches to the stem in aborted

buds (60x).

 

10.

11.

BIBLIOGRAPHY

Abeles, B.F. 1966. Effect of ethylene on Auxin tranSport. Plant
Physiol. 41:946-948.

Abeles, F.B. 1973. Ethylene in Plant Biology. Academic Press,
New York. pp. 87-196.

Ammon E. 1977. The effect of different light portions of the
sunlight spectrum on ethylene evolution in peach apices.
Physiol. Plant. 39:285-289.

Andersen, A.S. 1976. Regulation of apical dominance by ethephon,,
irradiance and C0 . Physiol. Plant. 37:303-308.

Apelbaum, A., and S.P. Burg. 1971. Altered cell microfibrillar
orientation in ethylene-treated Pisum sativum stems. Plant
Physiol. 48:648-652.

 

Apelbaum, A. and S. P. Burg. 1972. Effect of ethylene on cell
division and deoxyribonucleic acid synthesis in Pisum sativum.
Plant Physiol. 50:117-124.

 

Apelbaum, A. and S. P. Burg. 1972. Effects of ethylene and 2, 4 -
dichlorophenoxyacetic acid on cellular expansion in Pisum
sativum. Plant Physiol. 50:125-131.

Apelbaum, A. gt_pl. 1972. Effect of ethylene on cellular
differentiation in etiolated pea seedlings. Amer. J. Bot.
59(7):697—705.

Armitage, M.A. 1980. Effects of light and temperature on physio-
logical and morphological responses in hybrid geranium and mari-
golds. PH.D. Thesis. Michigan State University.

Berlyn, P.G. and J.P. Miksche. 1976. Botanical microtechnique
and cytochemistry. Iowa State University Press. Ames. Iowa.

Beutelmann, P. and H. Kende. 1977. Membrane lipids in senescing
flower tissue of Ipomoga tricolor. Plant Physiol. 59:888-893.

50

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

51

Beyer, E. Jr. 1976. Silver ion: A potent antiethylene agent
in cucumber and tomato. HortScience. 11(3):195-196.

Beyer, E. Jr. 1976a. A potent inhibitor of ethylene action in
plants. Plant Physiol. 58:268-271.

Bradford, J.K. and S.F. Yang. 1981. Physiological reSponses of
plants to waterlogging. HortScience. 16(1):3-8.

Burg, S.P. 1962. The physiology of ethylene formation. Annu.
Rev. Plant Physiol. 13:265-302.

Burg, S.P. and E.A. Burg. 1968. Ethylene formation in pea
seedlings; its relation to the inhibition of bud growth caused
by indole-3-acetic acid. Plant Physiol. 43:1069-1074.

Cameron, A.C. and Reid, M.S. 1981. The use of silver thiosulfate
complex as a foliar Spray to prevent flower abscission in
Zygocactus. HortScience. 16:761-762.

Cameron, C.A. and M.S. Reid. 1983. Use of silver thiosulfate to
prevent flower abscission from potted plants. In press.

Carlson, H.W. and E.M. Rowley. 1980. Bedding plants in R.A.
Larson Ed. Introduction to Floriculture. Ch. 19. pp. 477-522.

Carpenter, W.J. 1976. Environmental factors: Temperature,
light, carbon dioxide. In Bedding Plants. 2nd Ed.
Pennsylvannia Flower Growers. Chapter 16. pp. 166-176.

Chadwick, A.V. and S.P. Burg. 1967. An explanation of the
inhibition of root growth caused by indol-3-acetic acid.
Plant Physiol. 42:415-420.

Cox, R.J. 1967. Controlled flowering of carnations by dusk to
dawn lighting. Sparkes Tech. Report. A.G. Sparkes Limited.
Sussex, England.

Crocker, W. 23 a1. 1932. Ethylene induced epinasty of leaves
and the relaETOn of gravity to it. Contrib. Boyce Thompson.
Inst. 3:313-320.

Crocker, W. and L.I. Knight. 1908. Effect of illuminating gas
and ethylene upon flowering carnations. Bot. Gaz. 46:259-276.

DeMunk, J.W. 1972. Bud necrosis, a storage disease of tulips. III
The influence of ethylene and mites. Neth. J. P1. Path. 78
(168-178).

26.

27.

28.

29.

30.

31.

32.

33.

34.

35.

36.

37.

38.

52

Doupt, L.S. 1917. The response of plants to illuminating gas.
Bot. Gaz. 63:209-224.

El-Beltagy, A.S. and M.A. Hall. 1974. Effect of water stress

upon endogenous ethylene levels in Vicia Faba. New Phytol.
73:47-60.

 

Cummins, J.N. and P. Fiorino. 1969. Pre-harvest defoliation of
apple nursery stock using ethrel. HortScience. 4:339-341.

Elmer, O.H. 1932. Growth inhibition of potato Sprouts by the
volatile products of apples. Science. 75:193.

Ernest, C.L. and J.G. Valdovinos. 1971. Regulation of auxin
levels in Coleus blumei by ethylene. Plant Physiol.
48:402-406.

 

Farhoomand, M.B. £3 21. 1980. Pulsing Gladiolus hybrida
"Captain Busch" with silver or quaternary ammonium compounds
before low temperature storage. Acta Hort. 109:253-258.

 

Field, J.R. 1981. A relationship between membrane permeability
and ethylene production at high temperatures in leaf tissue of
Phaseolus vulgaris L. Ann. Bot. 48:33-39.

 

Futura K. and K.S. Nelson. 1953. The effect of high night
temperatures on the development of chrysanthemum flower buds.
Proc. Amer. Soc. Hort. Sci. 61:548-550.

Gilbert, D.A. and K.C. Sink. 1970. The effect of exogenous
growth regulators on keeping quality in poinsettia. J.
Amer. Soc. Hort. Sci. 95:784-787.

Gleason, A.H. and A. Cronquist. 1963. Manual of vascular
plants. D. VanNostrand Co. N. York. pp. 688.

Hackett, W.P., R.M. Sachs. 1966. Flowering in Bougainvillea
"San Diego Red". J. Am. Hort. Sci. 88:606-612.

 

Halevy, A.H. and A.M. Kofranek. 1977. Silver treatment of
carnation flowers for reducing ethylene damage and extending
longevity. J. Am. Soc. Hort. Sci. 102:76-77.

Halevy, A.H. and S. Mayak. 1981. Senescence and post harvest
physiology of cut flowers, part 2. Hort. Rev. 3:59-143.

39.

40.

41.

42.

43.

44.

45.

46.

47.

48.

49.

50.

51.

53

Hillman, J.R. and H.Y. Yeang. 1979. Correlative inhibition of
lateral bud growth in Phaseolus vulgaris L. Ethylene and the
physical restriction of apical growth. J. EXp. Bot.
30:1075-1083.

 

Hitchcock, E.A. gt at. 1932. Effect of illuminating gas on the
lily, narcissus, tulip and hyacinth. Boyce Thompson Inst.
Contr. 4:155-176.

Holliday, W.G. and D.P. Watson. 1953. Influence of temperature
on the flowering and calyx splitting of greenhouse carnations.
Proc. Amer. Soc. Hort. Sci. 61:538-542.

Holm, R.E. and F.B. Abeles. 1967. The role of ethylene in 2,4-D
induced growth inhibition. Planta. 78:293-304.

Jackson, M.B. and D.J. Campbell. 1975. Movement of ethylene
from roots to shoots, a factor in the responses of tomato
plants to waterlogged soil conditions. New Phytol. 74:
397-406.

Johansen, A.D. 1940. Plant microtechnique. McGraw-Hill Co.
N. York. London.

Kang, 6.8. and S.P. Burg. 1973. Influence of ethylene on
nucleic acid synthesis in etiolated Pisum sativum. Plant
and Cell Physiol. 14:981-988.

 

Kawase, M. 1972. Effect of flooding on ethylene concentrations
in horticultural plants. J. Amer. Soc. Hort. Sci. 97:584-588

Kender, £3 31. 1969. Stimulation of rhizome and shoot growth of
the lowbush blueberry by (2-chloroethane) phOSphonic-acid.
Can. J. Plant Sci. 49:95-96.

Kinet, J.M. 1977. Effect of light conditions on the development
of the inflorescence in tomato. Sci. Hort. 6:15-26.

Lyon, C.J. 1970. Ethylene inhibition of auxin tranSport by
gravity in leaves. Plant Physiol. 45:644-646.

Mae, T. and C.R. Vonk. 1974. Effect of light and growth
substances on flowering of Iris x Hollandica cv. Wedgewood.
Acta Bot. Neerl. 23:321-331.

 

Mastalerz, J.W. 1965. Bud blasting in Lilium longiflorum L.
Proc. Amer. Hort. Sci. 65:483-492.

 

52.

53.

54.

55.

56.

57.

58.

59.

60.

61.

62.

63.

64.

54

Mastalerz, W.J. 1977. The Greenhouse Environment. pp.283-338.
John Wiley and Sons. N. York.

Maxie, E.G. and J.G. Crane. 1968. Effect of ethylene on growth
and maturation of the fig, Ficus carica L. fruit. J. Amer.
Soc. Hort. Sci. 92:255-267.

 

Mayak, S. and A.H. Halevy. 1980. Flower senescence. In
Senescence in Plants. Thimann, V.K. ed. pp.131-156. CRC
Press. Inc. Florida.

Miller, R.O. and D.C. Kiplinger. l962. Two-year study on poin-
settia habits. Flor. Rev. 131 (3390):59-60.

Miranda, M.R. 1981. Studies on petal abscission in hybrid
geranium. PH.D. Thesis. Michigan State University.

Mor, Y. gt a1. 1981. Effect of silver thiosulfate pretreatment
on vase life of cut standard carnations, spray carnations and
gladiolus after a transcontinental truck shipment.
HortScience. 16(6):766-768.

Morgan, W.P. and H.W. Gausman. 1966. Effects of ethylene on
auxin transport. Plant Physiol. 41:45-52.

Nicols, R. 1971. Induction of flower senescence and gynaecium
develOpment in carnation by ethylene and 2-chloroethy1-phos-
phonic acid. J. Hort. Sci. 46:323-332.

Nicols, R. 1982. Effect of delayed silver thiosulfate pulse
treatments on carnation cut flower longevity. HortScience.
17(4):600-601.

Reid, ”-5-.££.21- 1980. Pulse treatments with the silver
thiosulfate complex extend the vase life of carnations. J.
Amer. Soc. Hort. Sci. 105:25-27.

Sacalis, J.N. 1978. Ethylene evolution by petioles of sleeved
poinsettia plants. HortScience. 13:594-596.

Saltveit, M.E. Jr. and D.R. Dilley. 1978. Rapidly induced
wound ethylene from excised segments of etiolated Pisum
sativum cv. Alaska 11: oxygen and temperature debEfiHEficy.
Plant Physiol. 61:675-679.

Salveit, M.E. Jr. 33 31. 1978. Silver ion inhibits ethylene
synthesis and action in ripening fruits. J. Amer. Soc.
Hort. Sci. 103(4):472-475.

65.

66.

67.

68.

69.

70.

71.

72.

73.

74.

75.

76.

77.

55

Salveit, M.E. Jr. gt 31. 1979. Mechanical stress induces
ethylene production and epinasty in poinsettia cultivars.
J. Amer. Soc. Hort. Sci. 104(4):452-455.

Sass, E.J. 1958. Botanical microtechnique. The Iowa State
University Press. Ames. Iowa.

Szendel, A. 1938. The effect of temperature on Splitting of
carnations. Proc. Amer. Soc. Hort. Sci. 36:760-767.

Valdovinos, G.J. gt_gl, 1967. Effect of ethylene and
gibberellic acid on auxin synthesis in plant tissues. Plant
Physiol. 42:1803-1806.

Veen, H. 1979. Effects of silver on ethylene synthesis and
action. Planta. 145:467-470.

Veen, H. and S.C. Van de Geijn. 1978. Mobility and ionic form of
silver as related to longevity of cut carnations. Planta.
140:93-96.

U.S.D.A. 1982. Floriculture crops - production area and sales,
1980 and 1981. Intentions for 1982. U.S. Government Printing
Office. Washington.

Wagner, D.L. and W.D. Holley. 1953. Usually high temperatures
cause carnation calyxes to Split. Colorado Flower Growers
Assoc. Bul. 43:1-3.

Weaver, R.J. gt a1. 1972. Translocation of 1,2 ‘hc (2-chloro-
ethyl)-phosphonic acid (ethephon) in Thompson seedless grapes.
Physiol. Plant. 26:13-16.

Webster, 0.8. 1968. Anatomical aspects of abscission. Plant
Physiol. 43:1512-1544.

Yang, F.S. 1980. Regulation of ethylene biosynthesis. Hort-
Science. 15(3):238-243.

Yeang, Y.H. and J.R. Hillman. 1981. Control of lateral bud
growth in Phaseolus vul aris L. by ethylene in the apical
shoot. J. EXp. Bot. 32:395-404.

Zieslin, N. and A.H. Halevy. 1976. Flower bud atrophy in
Baccara roses. Part 6. The effect of environmental factors
on gibberellin activity and ethylene production. Physiol.
Plant. 37(4):331-335.

78.

79.

80.

81.

56

Zimmerman, P.W. gt El. 1931. The response of plants to illumi-
nating gas. Proc. Amer. Soc. Hort. Sci. 1930:53-56.

Zimmerman, W.P. gt 31. 1933. Initiation and stimulation of
roots from exposure of plants to carbon monoxide gas.
Contrib. Boyce Thompson Inst. 5:1-17.

Zimmerman, W.P. and A.E. Hitchcock. 1933. Initiation and
stimulation of adventitious roots caused by unsaturated hydro-
carbon gases. Boyce Thompson Inst. 5:351-369.

Zimmerman, P.W. and F. Wilcoxon. 1935. Several chemical growth
substances which cause initiation of roots and other responses
in plants. Contrib. Boyce Thompson Inst. 7:209-229.