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ABSTRACT

THE INFLUENCE OF CARBON DIOXIDE AND ETHYLENE
PREPLANT SEED TREATMENT ON RESPIRATION AND
GERMINATION OF TOMATO AT Low TEMPERATURES
by

William J. Sanok

The interactiOn of carbon dioxide (C02) and ethylene
(CZHA) gas on imbibed tomato (Lycopersicon esculentum Mill.)
seed as a preplant treatment was investigated. Imbibed
tomato seeds (cv. Heinz 1439) were placed into sealed jars
and treated with three levels of C02 and four levels of C2H4.
After 24 hours at 20°C the seeds were removed, air dried, and
assayed for germination at suboptimal temperatures.

Monitored levels of gas during the treatment indicated
that absorbing C2H4 with potassium permanganate resulted in
reduced respiration as measured by C02 evolution when com-
pared to treatments where C2H4 was present. The level of
evolved C02 reached 0.3% after 24 hours and approximately 12%
after six days.

Seeds treated with C02 and C2H4 and then dried have a
carry-over effect which can be manifested later during germi-
nation at low temperatures.

There was little effect of treatments on speed or per-
cent germination at temperatures above 15.5°C. Below this
temperature the levels of C02 and C2H4 during the treatment
became important. The most rapid germination at 15.5°C,

15-hour days and 10°C, 9-hour nights in soil and at 12.2°C

continuous temperature in Petri dishes occurred when C02
was allowed to evolve during the initial treatment or when
5% C02 was complimented with additional (60 ppm) C2H4. If
C02 was absorbed by lime, the high treatment rate (30 and 60
ppm) of C2H4 was inhibitory to germination in both the soil
and Petri dish assay.

It appears that a balance of the two gases must exist
and that a combination of these can be successfully used
before planting to increase the germination rate at low

temperatures.

THE INFLUENCE OF CARBON DIOXIDE AND ETHYLENE
PREPLANT SEED TREATMENT ON RESPIRATION AND

GERMINATION OF TOMATO AT LOW TEMPERATURES

By

William John Sanok

A THESIS

Submitted to

Michigan State University

in partial fulfillment of the requirements

for the degree of

MASTER OF SCIENCE

Department of Horticulture

1972

ACKNOWLEDGMENTS

The author wishes to express his sincere appreciation
to Professor Hugh Price for his help as advisor and Chairman
of the advisory committee, and to Professors Donald Penner
and Robert Herner for their guidance as this work was being
conducted and for their review and suggestions in the prepa-
ration of this manuscript.

The author also wishes to thank those members of the
Department of Horticulture who made their laboratory

facilities available during this period.

11

TABLE OF CONTENTS

Title
List of Tables
List of Figures

Introduction
Literature Review

Materials and Methods
Section I
C02 and C2H4 Preplant Treatments
Section II
Ethephon Treatments
Section III
Gibberellic Acid (GA3)

Results and Discussion
Section I
C92 and C2H4 Preplant Treatments
Section II
Ethephon Treatments
Section III
Gibberellin Treatments

Summary and Conclusion
List of References
Appendix

List of Binomials of Plants Used in the
Literature Review

iii

13

15

16

16

29

33

35

37

Title

LIST OF TABLES

of Table

 

Table

Table

Table

Table

Table

Table

Table

Table

Table

Table

l.

10.

Levels of carbon dioxide and ethylene
monitored during tomato seed treatment

Monitored levels of Z C02 at the begin-
ning and after 72 hours in Mason jars
with and without potassium permanganate

Effect of
on number
12.2°C in

carbon dioxide and ethylene
of germinated tomato seeds at
Petri dishes (50 seeds total)

Effect of carbon dioxide and ethylene

on the number of germinated tomato seeds
in soil at 10°C night and 15.5°C day
temperatures (25 seeds total)

Effect of carbon dioxide and ethylene

on germination of tomato seeds in soil
at 10°C night and 15.5°C day tempera-

tures (25 seeds total)

Effect of carbon dioxide and ethylene
on germination of tomato seeds in Petri
dishes at 12.2°C (50 seeds total)

Effect of

nation of
(50 seeds

ethephon treatments on germi-
tomato seeds in field plots
total per plot)

Effect of granular
germination of two
and one of cabbage

ethephon on seed
varieties of tomatoes
on a sandy loam soil

Effect of granular ethephon on germina-
tion of tomato seeds at 15.5°C day and
10°C night temperatures (50 seeds total)
seeded July 14

Effects of GA3 on seed germination of
tomato and cabbage seed at 15.5°C day
and 10°C night temperatures

iv

Page

17

18

24

25

27

28

3O

31

32

34

LIST OF FIGURES

Title of Figure

Figure l. Jar used to treat imbibed tomato seed

Figure 2. C02 measured over 24 hours during
seed treatment

Figure 3. C02 measured over a six-day period
during seed treatment

20

22

INTRODUCTION

Direct seeding of vegetables has increased greatly over
the past several years. Contributing to this development
are: 1) increased cost of labor for transplanting, 2) the
development of better planting units that can place small
seeds accurately, 3) the development of good herbicides that
reduce weed competition, 4) the decreased spread of plant
bed diseases, 5) the trend toward larger farms and more
mechanization.

Direct seeding of tomatoes (Lycopersicon esculentum

 

Mill.) in particular has increased because of these develop-
ments. One of the main problems in direct seeded tomatoes
has been the failure to obtain a desired plant population and
distribution because of cold, wet conditions that often occur
during the spring in temperate areas of the United States.
Therefore, uniform germination and rapid emergence is needed
in direct seeded tomatoes during these periods of unfavorable
conditions for optimum production.

A great deal of work has been done with seed treatments,
but most of this has been limited to overcoming dormancy in
crops such as the legumes and lettuce. Less has been done
to decrease the minimum germination temperature of non—

dormant seeds. Kotowski in 1926 (21) reported that the

2
percentage and speed of germination were not increased by
using chemicals over diStilled water. He used germinating
temperatures of 25°C for parsnip and pepper and 11°C for
spinach. These temperatures should not be limiting germina-
tion in these crops. Ells (11) reported that K3P04 and KN03
treatment stimulated germination in tomatoes when seeds were
exposed to 10°C night temperature. 0yer and Koehler (26)
also discussed a method of treating tomato seeds with aerated
nutrient solutions to hasten germination. They found that
the effect depended partly on maintaining an osmotic concen-
tration high enough to prevent germination during treatment
and then drying the seed quickly before germination could
occur.

Mayer and Poljakoff-Mayber report (24) on the use of
KNO3, thiourea, Gibberellin and C02 to increase germination
of seeds. In most cases these treatments were used to over-
come dormancy or substitute for light or some other require-
ment.

Pollock and Toole in 1966 (29) found that lima beans
are extremely sensitive to low-temperature injury during the
early stage of imbibition. In 1969 Pollock (28) found that
temperature sensitivity was controlled by the amount of
water in the seed at the time that imbibition of water began.
Increasing initial seed moisture to 20% eliminated tempera-
ture sensitivity. Christiansen (8) pregerminated cotton
seeds at 31°C, redried them, and found that protection against

chilling injury was retained. He later found that initial

3
seed moisture was the controlling factor and that seeds
were sensitive to temperature only when imbibition was
started at moisture levels below 14% (9). Phillips and
Youngman (27) found that under a mean soil temperature below
20°C more seeds emerged as moisture content was increased
from 8 to 11 or 14% in grain sorghum. Bleak and Keller (4)
reported that germination, seedling emergence, and initial
root and shoot elongation were all hastened by preplanting
treatment applied to the seeds of seven forage species.
Drosdov and Sokolova (10) found that treating flax seeds with
boric acid solution before planting increased drought toler-
ance. Mart'yanova gt al.(23) increased the fruit yield of
tomatoes by soaking seeds in water for 30 hours and then
drying before planting.

Carbon dioxide (C02) has been reported to overcome seed
dormancy in a number of cases. Thornton in 1935 (33) showed
that 40% C02 can break thermodormancy in lettuce seed that
had been induced by 35°C treatment. Carr in 1961 (6) listed
a number of other cases where C02 had broken dormancy in seed.
Usually, the level of C02 needed to break dormancy is quite
high, and many workers feel that these concentrations are too
high to be encountered by seeds in nature. However, promotive
effects of lower C02 concentrations have been reported. Hart
and Berrie (15) found that 3% C02 overcame the inhibition of

light in Avena fatua L. Ballard in 1958 (3) reported that

 

.5 to 5% C02 can overcome dormancy in subterranean clover

seed. He suggests that because of the capacity of imbibed

4
seed to produce C02, the number of seeds in relation to the
volume of air around them is important. Under field condi-
tions, mechanical impedance of the soil is frequently over-
come much more effectively by an aggregate of germinating
seeds than by single seedlings (20).

Esashi and Leopold (12) and Ketering and Morgan (18) have
shown that imbibed seeds of subterranean clover and peanuts
produce CZH4 as well as C02 and that their germination is pro-
moted by both of these substances, probably in an independent
manner. :In comparing three varieties (two dormant and one
non-dormant) of clover, Esashi and Leopbld found that more
C2H4 is produced by the non-dormant variety and that the
production of CZHA markedly preceeds the first emergence of
the radicle.

Abeles and Lonski (2) reported that non-dormant lettuce
seeds produced ten times as much C2H4 as dormant ones and
concluded that this is an effect of germination rather than a
controlling factor. They also reported that C02 did not act
as a competitive inhibitor of C2H4 in lettuce seed germination
as it does in a number of other processes such as root (7)
and stem (5) growth inhibition, fruit ripening (l9), celery
blanching (22), flower wilting (30), abscission (l), hook
opening (17), and peroxidase formation (13).

Negm, Smith and Kumamoto (25) reported on the interaction
of C02 and C2H4 in completely overcoming thermodormancy of
lettuce seeds at 35°C. The combination is effective if it

is added to seeds either at the start or after several days

5
of imbibition. The action of C2H4 is dependent upon the
C02 level present in the atmosphere surrounding the seeds.
When 002 is trapped by KOH the C2H4 effect is essentially
nil. Takayanagi and Harrington (32) found that C2H4 gas
around the seed will restore rape seeds that are declining
in vigor to almost original vigor. They suggest that degrada-
tion of the C2H4 producing system or insufficiency of the
substrate(s) which normally give rise to C2H4 may occur in
aged seeds. Harrington (14) speculated on the possibility of
treating seeds with (2-chloroethy1) phosphonic acid (ethephon)
to provide a C2H4 atmosphere around the germinating seed,
thereby improving vigor and speeding emergence.

Stewart and Freebairn (31) state that it is possible
CZH4 may be an intermediate between auxin and the other
physiological responses attributed to auxin in some plants.
Jones (16) concluded that C2H4 does not affect a-amylase
synthesis in barley but rather that its effect is on a-amylase
secretion from aleurone cells.

Varner gt 31 (34,35) have shown that a-amylase is pro—
duced dg_ggzg in aleurone layers following treatment with
gibberellic acid (GA3). Villiers (36) states that dormancy
may be due to the presence of growth inhibitors, the absence
of growth promoters or a combination of both. The growth
promoters referred to most often are the gibberellins.

In an attempt to find a treatment that would stimulate
germination of tomatoes at suboptimal temperatures, the

following experiments were performed during the period 1 April

6
to 1 September, 1972. Section I deals with the interaction
of C02 and C2H4 on tomato seeds, Section II deals with the
effect of ethephon on tomato seed germination and Section III
deals with the effect of GA3 on cabbage and tomato seed germi-

nation.

MATERIALS AND METHODS

Section I

C02 and C2H4 Preplant Treatments

 

Tomato seeds (cv. Heinz 1439) were treated with various
concentrations of C02 and C2H4 gas in closed containers. A
piece of 7-cm diameter Whatman #1 filter paper was placed in
the bottom of a .473-L Mason jar and was soaked with 3 ml dis-
tilled water. Approximately 500 dry tomato seeds (measured by
a volume of 2.3 cc) were placed on the moist paper in each jar.
A lid with tightly fitted serum caps was used to seal each jar
(Fig. 1). The serum caps were used so that 002 and C2H4 could
be added with a syringe and samples of gas could be taken
periodically. Twelve jars were used for three levels of C02
and four levels of CZH4. An additional treatment consisted
of imbibing seeds with distilled water for this period in
an unsealed jar. The treatments were then held in a room
at 20°C for 24 hours.

The three levels of 002 were obtained by l) absorbing
C02 with lime. The amount, 1.25 grams, of lime was placed on
a 4.1l-cm square plastic weighing tray over the seed to
absorb the C02 from around the seed; 2) allowing the C02 to
evolve naturally; 3) adding 002 with a syringe to reach a
level of 5%. To do this, 26 cc of air was withdrawn from the

jar and the same volume of 100% C02 was added. The physical

Figure 1. Jar used to treat imbibed tomato seed

 

 

Serum Caps
lid

Mason Jar

Absorber
Tray
Seed
Paper

 

 

 

 

 

 

10
characteristics of gases are dependent on pressure and
temperature; therefore, through several trials, it was de-
termined that 26 cc of 100% CO2 was needed to obtain this
level.

The four levels of C2H4 were obtained by l) absorbing
C2H4 with potassium permanganate. About 1.25 grams of
potassium permanganate coated on perlite granules* was placed
on weighing trays to absorb the C2H4 from around the seed;
2) allowing the C2H4 to evolve; 3) adding C2H4 to obtain
approximately 30 ppm and 4) adding C2H4 to obtain 60 ppm.
The C2H4 was added by diluting 1 cc of 100% C2H4 in a 30-cc
syringe and then taking 0.5 cc from this and injecting it
into a jar to obtain 30 ppm. One cc was used to obtain
60 ppm.

The levels of both gases were monitored at the beginning
of the experiment and at 6, 12, and 24 hours. Samples of
the gas were withdrawn from each jar with a 1-ml plastic
syringe inserted through the serum cap and assayed using
gas chromatography. The C02 concentration was determined
on a Perkin-Elmer 1543 gas chromatograph employing a column
of silica gel. C2H4 analysis was performed employing a
Varian 1720 gas chromatograph equipped with a .32 x 76.2-cm
column of activated aluminum connected to a flame ionization
detector. The results of the gas chromatography are shown
in Table 1.

After treatment for 24 hours at 20°C, the seeds were
removed from the jars and placed in open Petri dishes to dry

* Trade name, "Purafil." H. E. Burroughs and Assoc., Inc.,
Chamblee, Georgia.

11
for 24 hours at room temperature. Germination tests of the
seeds were run by placing them in Petri dishes and cups.
Fifty seeds were counted and placed in a Petri dish on 9-cm
diameter Whatman #2 filter paper which had been soaked with
3 ml distilled water. These were then placed in a dark
growth chamber with a continuous temperature of 12.2°C.
Twenty—five seeds were counted and placed in a 236—cc styro-
foam cup which contained 176 cc sterilized greenhouse soil
which had been moistened with 30 ml distilled water. The
seeds were covered with 30 cc of soil. The cups were then
placed in a growth chamber with 15 hours of light at 15.5°C
and 9 hours dark at 10°C. To minimize the effect of unequal
chamber temperatures, the cups were rotated daily. Watering
was done on a daily basis as needed. As a control, untreated
unimbibed seeds were also planted in both tests. Each
treatment was replicated five times.

Germination counts in the Petri dishes were made at
three-day intervals and germination consisted of visible
radical emergence. In the cups, counts were made daily as
the seedlings emerged from the soil.

An analysis of variance was performed on each experiment,
and treatment means were compared using Duncan's Multiple
Range Test. A factorial AOV was used in comparing the first
12 treatments and a randomized complete block design was used
in comparing the water-imbibed and untreated seeds as addi-
tional treatments.

In an additional experiment, the treated tomato seeds

12
were kept in the sealed jars for six days and the amount of
C02 and C2H4 was monitored regularly to determine the levels

of these gases over an extended period.

MATERIALS AND METHODS

Section II

Ethephon treatment

 

Tomato seeds (cv. Heinz 1439) were soaked in solutions
of O, 40, 80 or 160 ppm (2-chloroethyl) phosphonic acid
(ethephon) for 30 or 60 minutes. The seeds were then removed
and dried at room temperature for 24 hours. The dried seeds
were then counted with 100 seeds being placed in each Petri
dish, 50 seeds in each cup and 50 seeds planted in each plot
in the field. In each case there were five replications.

The Petri dishes were prepared the same as in Section I.
In the cups, Jiffy Mix was used instead of soil. These were
then placed in a dark growth chamber at 12.5°C. The field
plots were planted with a hand-operated Planet Jr. seeder
adapted with a cone distributor. Seeding was done on May 10
and the soil temperature was l6.6°C at the 5-cm level. The
soil was a Fox sandy loam. Germination counts were made
periodically in the Petri dishes and cups and, after 19 days,
in the field.

Granular ethephon (5% G) at the rates of 0, 0.28, 11.2,
and 44.8 kg/ha were applied as an in-row seed treatment on two
cultivars of tomato (Heinz 1350 and MH 1) and one cultivar

of cabbage (Golden Acre). These were seeded on a sandy

l3

l4

loam soil at Sodus, Michigan on July 5. Germination was
determined July 13.

Granular ethephon was also mixed with dry Jiffy Mix
to dilute the chemical and apply it as a seed treatment
for tomatoes (cv. Heinz 1439) in cups. The rates used
were 0, 1.12, 2.24, 4.48, 8.96 and 17.92 kg/ha. These
were then placed in growth chambers with 15.5°C for lS-hour
days and 10°C for 9-hour nights. The seeds were planted

July 14 and germination counts were made July 24 and 27.

MATERIALS AND METHODS

Section III

Gibberellic Acid (GA3)

 

Tomato (cv. Heinz 1439) and cabbage (cv. Golden

Acre)

were treated with various concentrations of gibberellic acid

(6A3) for one hour. The concentrations used were 0,
2, 4 and 8 x 10'4 M.

After treatment, the seeds were removed and air
for 24 hours. Seeds were then counted and placed in
foam cups in Jiffy Mix as in Sections I and II. The
were then placed in the growth chamber at 15.5°C for

days and 10°C for 9-hour nights. Germination counts

0.5, 1,

dried
styro-
cups
15-hour

were made

on cabbage 10 days after seeding and on tomatoes 14 days

after seeding.

15

RESULTS AND DISCUSSION

Section I

002 and C2H4 Preplant Treatments

 

The monitored levels shown in Table 1 indicate that
there was very little if any change in C2H4 level during
the 24-hour treatment. However, where potassium permanganate
was used to absorb the C2H4, the C02 evolution is reduced
about 50% compared to the other treatments containing
evolved or added C2H4 after 24 hours. The results given
in Figure 2 are averages of five repeated treatments and
demonstrate that CZH4 has an effect on respiration in
imbibed tomato seeds as measured by C02 evolution. To
verify that this was due to a difference in respiration and
not C02 absorption by the potassium permanganate, several
jars containing a known concentration of C02 were set up
with and without this absorber. Samples were taken periodi-
cally and no differences were found over 72 hours (see
Table 2).

The levels of 002 over the six-day period are given in
Figure 3. The treatment containing potassium permanganate
shows a lower C02 evolution up to 96 hours. However, after
96 hours the rate increased and after 144 hours the C02 level

was the same as the treatment which contained 30 ppm C2H4.

l6

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om.~m o.mm mo.qm mm.Hm em.m Hm.m ma.m Hm.m sag om Nm
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18

Table 2. Monitored levels of % C02 at the beginning and
after 72 hours in Mason jars with and without
potassium permanganate

Treatment 0 hours 72 hours Decrease

 

Without KMn04 1.95 1.58 0.37

With KMno4 1.85 1.39 0.46

 

Figure 2. C02 measured over 24 hours during seed
treatment

19

 

 

 

Pom-l Carbon Null.

 

 

 

 

'35 1' - absorbed ethylene +
+ evolved ethylene
Dadded ethylene

.304- D

.25i

120$

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floors

Figure 3.

C02 measured over a six-day period during
seed treatment

21

 

 

 

 

+ absorbed ethylene
A evolved ethylene
D added ethylene °
. absorbed ethylene + 5% carbon dioxide
16$ 0 evolved ethylene + 5% carbon dioxide
9 added ethylene + 51 carbon dioxide
.
14 ‘ a
A
9
12 r
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8* /°
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41
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23
At this time the oxygen level had decreased and could have
been limiting.

These same trends are noticed in the treatments contain-
ing 5% C02 at the beginning. The treatment which contained
5% C02 and the C2H4 absorber lagged behind in respiration for
72 hours but then increased and resulted in slightly more
002 evolved than the treatment containing added C02 and
30 ppm C2H4. In both cases, the greatest C02 evolution
occurred if C2H4 had been allowed to evolve freely. In this
extended treatment, the evolved C2H4 reached a level of 0.2
ppm after six days at all levels of C02.

Germination results

 

All of the gas and water-imbibed treatments were better
than the control at low germination temperatures in the Petri
dish study. The results in Table 3 indicate that the best
germination occurred where CZH4 was absorbed and the C02
allowed to evolve or if 60 ppm C2H4 and 5% C02 were added.
The slowest germination occurred in the untreated control,
the water-imbibed seeds and in the treatments where C02 was
absorbed with lime and 30 and 60 ppm C2H4 added.

Table 4 is a list of the results of the germination
counts in the soil emergence test. The evolved C02 and the
added (5% C02 and 60 ppm C2H4) gas treatments showed the best
early germination. The slowest germination was in the con-
trol and where C02 was absorbed and 30 or 60 ppm CZH4 was
added after 13 days in Petri dishes and eight days in soil.

The high concentration of 02H4 in the absence of C02

 

24

 

 

Table 3. Effect of carbon dioxide and ethylene on number of
germinated tomato seeds at 12.2°C in Petri dishes
(50 seeds total)
Treatment Days after seeding
002 C2H4 13 16 19
absorbed absorbed 2.2 bc 9.8 cdef 19.6 be
absorbed evolved 4.0abc 17.8abc 27.0ab
absorbed 30 ppm 1.2 c 12.2 bcde 22.0abc
absorbed 60 ppm 1.6 c 10.2 bcdef 18.2 bc
evolved absorbed 5.0ab 21.6a 30.0a
evolved evolved 3.6abc 15.8abcd 25.8ab
evolved 30 ppm 1.8 bc 10.0 cdef 21.4abc
evolved 60 ppm 3.0 16.8abcd 26.4ab
5% absorbed 2.2 be 9.0 def 19.0 bc
5% evolved 4.Zabc 15.6abcd 27.0ab
5% 30 ppm 2.0 bc 6.0 ef 14.6 c
5% 60 ppm 5.6a 18.4ab 29.2a
imbibed 1.6 c 8.8 def 15.6 c
control 1.0 c 2.6 f 5.4

 

Means within columns followed by common letters are not sig-
nificantly different at the 1% level (Duncan's Multiple
Range Test).

25

 

 

 

Table 4. Effect of carbon dioxide and ethylene on the
number of germinated tomato seeds in soil at 10°C
night and 15.5°C day temperatures (25 seeds total)

Treatment Days after_planting
002 C2H4 8 9 10 ll 15

absorbed absorbed 1.83bc 4.43bcd 16.63 18.43, 23.23

absorbed evolved 2.8abc 5.4abcd 14.2a 15.63 21.6 b

absorbed 30 ppm 0.6 c 2.83bcd 15.03 16.83 23.23

absorbed 60 ppm 1.0 bc 3.23bcd 14.23 15.63 22.83

evolved absorbed 3.63bc 7.03b 14.83 16.03 21.8 b

evolved evolved 4.6a 6.0abc 14.83 16.83 22.4 b

evolved 30 ppm 1.6abc 3.4abcd 15.03 16.03 22.0 b

evolved 60 ppm 4.03b 7.2a 16.03 17.63 22.0 b

5% absorbed 2.6abc 5.03bcd 16.63 17.03 22.6ab

5% evolved 1.4 bc 5.23bcd 15.23 15.83 21.0 b

5% 30 ppm 1.0 be 2.4 cd 15.63 16.03 22.2 b

5% 60 ppm 3.23bc 5.23bcd 14.03 15.23 21.4 b

imbibed 1.4 be 2.6 bcd 14.23 15.43 21.4 b

control 0.6 c 1.2 d 6.2 7.2 18.0 b

 

Means within columns followed by common letters are not
significantly different at the 1% level (Duncan's Multiple
Range Test).

26
is inhibitory to early germination in both of these tests.
In the soil, these treatments recovered and after 15 days,
there was no difference in the total number germinated.

The treatments where the 30 ppm of C2H4 was added tended
to have slower germination than the corresponding evolved
and higher concentration of C2H4.

In analyzing the 12 gas treatments as a factorial experi-
ment there was no significant interaction between the differ-
ent levels of C02 and C2H4 in the soil germination test.

Table 5 is a comparison of the mean effects of the three
levels of C02 over all levels of C2H4 and the mean effects

of the four levels of C2H4 over all levels of C02 on germi-
nation in soil. This indicates that at the first count there
was faster germination where C02 accumulated and there was
inhibition where C2H4 at 30 ppm was added. However, two days
later there were no significant differences in number of
emerged seedlings.

In the Petri dish study there were significant differences
due to interaction of C02 and C2H4 treatments (Table 6).

The same problem of inhibition occurred where the 30 ppm
concentration of C2H4 was used, similar to that expressed

in the soil emergence test. Treatments with evolved C02 and
absorbed C2H4 or 60 ppm added C2H4 resulted in faster
germination but after 19 days from seeding, there were smaller

differences among all treatments.

27

Table 5. Effect of carbon dioxide and ethylene on
germination of tomato seeds in soil at 10°C
night and 15.5°C day temperatures (25 seeds total)

Days after seeding

 

 

8 9 10
Level of C02
absorbed 1.55 a 3.95 b 15.00 a
evolved 3.45 b 5.90 a 15.15 a
5% added 2.05 a 4.45 a 15.35 a
Level of 02H4
absorbed 2.67 a 5.47 a 16.00 a
evolved 2.93 a 5.53 a 14.73 a
30 ppm 1.07 "b 2.87 b 15.20 a
60 ppm 2.73 a 5.20 a 14.73 a

 

Means within columns followed by common letters in each sub-
column are not significantly different at the 5% level
(Duncan's Multiple Range Test).

28

 

 

 

 

 

 

Table 6. Effect of carbon dioxide and ethylene on germina-
tion of tomato seeds in Petri dishes at 12.2°C
(50 seeds total)
13 days aftergplanting’ CZH4
absorbed evolved 30 ppm 60 ppm
absorbed 2.2 abc 4.0 abc 1.2 c 1.6 bc
C02 evolved 5.0 ab 3.6 abc 1.8 be 3.0 abc
5% 2.2 abc 4.2 abc 2.0 abc 5.6 a
16 days after planting C2H4
absorbed evolved 30 ppm 60 ppm
absorbed 9.8 bc 17.8 ab 12.2 be 10.2 be
002 evolved 21.6 a 15.8 ab 10.0 be 16.8 ab
5% 9.0 bc 15.6 ab 6.0 c 18.4 ab
19 days after planting 62H4
absorbed evolved 30 ppm 60 ppm
absorbed 19.6 abc 27.0 ab 22.0 abc 18.2 be
C02 evolved 30.0 a 25.8 ab 21.4 abc 26.4 ab
5% 19.0 abc 27.0 ab 14.6 c 29.2 ab

 

Means followed by common letters at the same date are not
significantly different at the 1% level (Duncan's Multiple
Range Test).

RESULTS AND DISCUSSION

Section II

Ethephon Treatments

There were no major differences in seed germinated due
to liquid ethephon treatments. The results given in Table 7
are averages of germinated tomato seeds taken on May 29.

The results of granular ethephon applications shown in
Table 8 indicate that there was no stimulation at the low
rates of application and that the high concentration was
inhibitory to germination. It is possible that high soil
temperature results in a greater release of C2H4 from ethe-
phon which causes inhibition of germination or toxic effects
in the seeds. In the growth chamber study there was no effect
of the chemical treatment (Table 9).

Because of lack of apparent beneficial results, no

further work was done with these approaches.

29

30

Table 7. Effect of ethephon treatments on germination
of tomato seeds in field plots (50 seeds total

 

per plot)

Ethephon rate Time of imbibition Average number
(ppm) (min.) of seeds germinated
O 30 24
0 60 19
40 30 27
4O 60 23
80 30 25
80 60 21
160 30 22
160 60 22
untreated control 18

 

There are no significant differences

31

Table 8. Effect of granular ethephon on seed germination
of two varieties of tomatoes and one of cabbage
on a sandy loam soil.

 

 

No. emerged seedlings il
Ethephon rate Tomato Tomato Cabbage
kg/ha (H 1350) (MH 1) (Golden Acre)
0 63.2 ab 45.8 a 31.0 a
0.28 67.0 a 37.5 ab 29.0 a
2.8 46.2 b 27.2 ab 9.8 b
11.2 24.0 b 12.0 be 1.8 b
44.8 2.8 c 0.5 c 0.8 b

 

l/Counts made eight days after application.

Means within columns followed by common letters are not
significantly different at the 1% level (Duncan's Multiple
Range Test).

32

Table 9. Effect of granular ethephon on germination of
tomato seeds at 15.5°C day and 10°C night
temperatures (50 seeds total) seeded July 14

 

 

Ethephon rate No. germinated seeds
kg/ha July 24 July 27
0 9.2 29.8
1.12 11.6 32.2
2.24 8.4 37.8
4.48 7.6 31.6
8.96 6.2 33.4
17.92 3.8 23.8

There are no significant differences.

RESULTS AND DISCUSSION

Section III

Gibberellin Treatments

 

Gibberellic acid at the low concentration (0.5 x 10'4 M)
gave the greatest stimulation for germination in cabbage and
at the high concentration (8 x 10'4 M) stimulated tomato
germination (Table 10). At the time of these experiments,
these results did not seem as important or as significant as
those observed in Section I. Therefore, no attempt was made
to follow up on these observations. However, since there is
promise of beneficial results with GA, there might be some
interaction between this hormone and the effects of 002 and/or

C2H4 as shown in Section I.

33

Table

10.

Effects of GA3 on seed germination of tomato

34

and cabbage seed at 15.5°C day and 10°C night

temperatures

GA concentration

Percent germinated

 

 

(M) Tomatoes Cabbage

0.5 x 10'4 68.5 b 85.2 a
1 x 10‘4 62.2 be 75.6 ab

2 x 10‘4 69.2 b 78.0 ab

4 x 10-4 66.0 bc 80.4 ab

8 x 10‘4 93.0 a 80.6 ab
imbibed control 56.6 c 82.0 ab
control 59.4' -c 71.6 b

 

Means within columns followed by common letters are not

significantly different at the 1% level (Duncan's Multi-
ple Range Test).

SUMMARY AND CONCLUSION

One of the most interesting results of these experiments
is the effect of C2H4 on the rate of respiration as measured
by the C02 evolved. Carbon dioxide is a known competitive
inhibitor of €2H4 action (1, S, 7, 13, 17, 19, 22, 30); but
in comparing treatments with absorbed C2H4 and evolved C02
with other treatments, it appears that C2H4 has an effect on
the production of C02 in imbibed tomato seeds. Therefore,
it seems reasonable to expect that some treatment with C2H4
can be used to increase respiration which, in turn, would
release energy to be used in the germination process. This
could be very important where low temperatures limit rapid
and uniform seed germination.

Another interesting observation is that seeds treated
with 002 and C2H4 for a period and then dried exhibit a
carry-over effect which can be manifested later under certain
environmental conditions.

As temperatures increased above 15.5°C, there was little
effect of treatment on rate of germination; but below this
temperature, the level of C02 and C2H4 became important. The
most rapid germination occurred if the C02 was allowed to
evolve freely and if the high rate of added C02 was compli-
mented with additional C2H4. Therefore, it appears that a

balance of the two gases must exist for optimum germination

35

36
at low temperatures.

Imbibed seeds have a great potential for the production
of C02. In the extended treatment for six days, the C02
level reached about 12%. Since 002 can stimulate germination,
this could explain the lower germination in direct seeded
crops where seed is spaced singly and the greater germination
in seeds planted close together (3). This preplant treatment
with C02 and C2H4 as described in Section I might be used to
stimulate germination later when planted in the field due to
the carry-over effect.

Other means of stimulating germination in seeds have
been found such as the gibberellins (20, 24), nutrient salts
(11, 26), etc. Since these work in a different way, the
action of C02 and/or C2H4 could be used to compliment them
and cause even greater stimulation under adverse conditions.
Because some treatments have a carry-over effect on later
germination, it may be possible to apply these methods, dry
the seeds, and later plant them in the field. Whether or
not this can be done on a commercial scale depends on the
degree of stimulation that can be achieved and whether or
not the expense can be recovered in final stand and yield.
From the results presented here, it appears that these
treatments show a great deal of promise and more work in this

area would be valuable.

LIST OF REFERENCES

10.

Abeles, F. B.
The role of ethylene, ethylene analogues,

dioxide,

Abeles, P. B.

LIST OF REFERENCES

and

and J.

and H. E.

oxygen.

Gahagan.

1968.

Plant Physiol.

Lonski.

1969.

lettuce seed germination by ethylene.
44:277-280.

Physiol.

Ballard, L.

seeds of subterranean clover (Trifolium subterraneum L).

A. T.

1958.

Abscission:

carbon

43:1255-1258.

Stimulation of

Plant

Studies of dormancy in the

I. Breaking of dormancy by carbon dioxide and by
activated carbon dust.

Burg, S. P.

and

and E. A.

W. Keller.
emergence of selected forage species following
preplanting seed treatment.

Burg.

J. Biol. Sci.

1972.

1967.

Crop Sci.

11:246-263.

Germination and

Molecular require-

ments for the biological activity of ethylene.

Plant Physiol.

Carr, D. J.

ment. In:
(W. Ruhland) Vol.

1961.

Berlin and New York.

Chadwick, A.

3-acetic acid.

V. and S.

Christiansen, M.

cottonseed.

Christiansen, M.

chilling injury to imbibing cottonseed.

Cotton Council, Beltwide Cotton Prod. Res.

p. 50.

Drosdov, N.

Issled.

P.

N. 1968.

N. 1969.

A. and G. P.

Inst.

L'na.

37

42:144-152.

737,

Burg.

Plant Physiol.

Chemical influences of the environ-
"Handbuch der Pflanzenphysiologie."
16, p.

Springer-Verlag,

1967. An explanation
of the inhibition of root growth caused by indole-

42:415-420.

Induction and prevention
of chilling injury to radicle tips of imbibing
Plant Physiol.

43:743.

Seed moisture content and

Sokolova. 1960.
boron pre-sowing treatment of seeds on the fiber
flax yields and its physiological peculiarities

depending on soil moisture content.

Tr.

6:96.

National

Conf.,

Influence of

Vseso.

Narch-

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

38

Ells, J. 1963. The influence of treating tomato seed
with nutrient solutions on emergence rate and seed-
ling growth. Proc. Amer. Soc. Hort. Sci. 83:684—
687.

Esashi, Y. and A. C. Leopold. 1969. Dormancy regula-
tion in subterranean clover seeds by ethylene. Plant
Physiol. 44:1470-1472.

Gahagan. H. E., R. E. Holm, and F. B. Abeles. 1968.
Effect of ethylene on peroxidase activity. Physiol.
Plantarum.

Harrington, J. F. 1970. The necessity for high-quality
vegetable seed. Hort. Sci. 6:550-551.

Hart, J. W. and A. M. M. Berrie. 1966. The germina-
tion of Avena fatua under different gaseous environ-
ments. Physiol. Plant. 19:1020.

 

Jones, R. L. 1968. Ethylene enhanced release of
a-amylase from barley aleurone cells. Plant Physiol.
43:442-444.

Kang, B. G., C. S. Yokum, S. P. Burg and P. M. Ray.
1967. Ethylene and carbon dioxide, mediation of
hypocotyl hook opening response. Science 156:958-959.

Ketering, D. L. and P. W. Morgan. 1969. Ethylene as
a component of the emanations from germinating peanut

seeds and its effect on dormant Virginia type seeds.
Plant Physiol. 44:326-330.

Kidd, F. and C. West. 1945. Respiratory activity and
duration of life of apples gathered at different
stages of development and subsequently maintained
at constant temperature. Plant Physiol. 20:467-504.

Koller, D. 1972. Environmental control of seed germina-
tion. Biology of Seeds, (Kozlowski) Academic Press,
New York and London.

Kotowski, F. 1926. Chemical stimulants and germination
of seeds. Proc. Amer. Soc. Hort. Sci. 23:173-176.

Mack, W. B. 1927. The action of ethylene in acceler-
ating the blanching of celery. Plant Physiol. 2:103.

Mart'yanova, K. L., Z. P. Gubanova and V. K. Zhurikhin.
1961. Presowing drought hardening of tomatoes under

conditions of a production experiment. Fiziol. Rast.
8:638.

Mayer, A. M. and A. Poljakoff-Mayber. 1963. The Germi-
nation of Seeds. Pergamon Press, Oxford.

 

25.

26.

27.

28.

29.

30.

31.

32.

33.

34.

35.

39

Negm, F. B., O. E. Smith and J. Kumamoto. 1972.
Interaction of carbon dioxide and ethylene in over-

coming thermodormancy of lettuce seeds. Plant
Physiol. 49:869-872.

0yer, E. B. and D. E. Koehler. 1966. A method of
treating tomato seeds to hasten germination and
emergence at suboptimal temperatures. Proc. XVII.
Intern. Hort. Congr. I, p. 626.

Phillips, J. C. and V. E. Youngman. 1971. Effect of
initial seed moisture control on emergence and yield
of grain sorghum. Crop Sci. 11:354.

Pollock, B. M. 1969. Imbibition temperature sensitivity

of lima bean seeds controlled by initial seed mois-
ture. Plant Physiol. 44:907-911.

Pollock, B. M. and V. K. Toole. 1966. Imbibition
period as the critical temperature sensitive stage
in germination of Lima bean seeds. Plant Physiol.
41:221-229.

Smith, W. H. and J. C. Parker. 1966. Prevention of
ethylene injury to carnations by low concentrations
of carbon dioxide. Nature 211:100-101.

Stewart, E. R. and H. T. Freebairn. 1969. Ethylene,
seed germination and epinasty. Plant Physiol.
44:955-958.

Takayanage, K. and J. F. Harrington. 1971. The enhance-
ment of germination rate of aged seeds by ethylene.
Plant Physiol. 47:521-524.

Thornton, N. C. 1935. Factors influencing germination
and development of dormancy in cockleburr seeds.
Contrib. Boyce Thompson Inst. 7:477.

Varner, J. E. and G. R. Chandra. 1964. Hormonal control

of enzyme synthesis in barley endosperm. Proc. Natl.
Acado SCio 1108., 52:100-106.

Villiers, T. A. 1972. Seed dormancy. Biology of Seeds
(Kozlowski), Academic Press, New York and London.

APPENDIX

LIST OF BINOMIALS OF PLANTS
USED IN THE LITERATURE REVIEW

Barley
Bean, lima
Celery
Clover, subterranean
Cocklebur
Cotton
Flax
Lettuce
Parsnip
Peanut
Pepper
Rape
Sorghum

Spinach

Hordeum vulgare L
Phaseolus lunatus L
Apium graveolens L
Trifolium subterraneum L
Xanthium sp. L

Gossypium sp. L

Linum sp. L

Latuca sativa L
Pastinaca sativa L
Arachis hypogaea L

Capsicum sp. L

Brassica napus L

'Sorghum vulgare Pers.

Spinacia oleracea L

N T

 

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