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SOME EFFECTS OF MALEIC HYDRAZIDE
OK CERTAIN PHYSIOLOGICAL RESPONSES OF
CELERY (APITJM GRAYEOLMS)

By
Hezekiah Jackson

A THESIS
Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
In partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY
Department of Horticulture
Year

1952

SOME EFFECTS OF MALEIC HYDRAZIDE
OH CERTAIN PHYSIOLOGICAL RESPONSES OF
CELERY (APIUM GRAVEOLENS)

By

Heaekiah Jacksem

AN ABSTRACT
Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY
Department of Horticulture
Year

Approved

19£>2

Hezekiah Jackson

The effects of foliage sprays of various concentrations
of raaleie hydrazide on the growth and development of Cornell
19 celery plants were determined under field and greenhouse
conditions.

Time of application, cold exposure of plants,

and soil nitrate levels were considered*

Storage tests

were also conducted to determine the effects of maleic
hydrazide applied as a preharvest foliage spray on the sugar
and nitrogen content of Cornell 19 and Utah 15 varieties
of celery which were stored for various periods of time at
33 + 2° P*

Finally a series of fresh tissue analyses were

carried out during the growing season to determine the
effects of maleic hydrazide treatments,

soil nitrate levels,

and temperature exposures on the soluble nitrogen content
of maturing Cornell 19 celery plants*
Foliage sprays of maleic hydrazide favored the develop­
ment of seedstalk initials in Cornell 19 celery when applied
at SO to 100 ppm to plants which were from 13 to 16 weeks
old*

I n striking contrast, when applied at £00 to 1000 ppm

to older plants, seedstalk elongation was inhibited*

Maleic

hydrazide did not have comparable influences on initiation
and inhibition of seedstalk formation and elongation,
respectively, under greenhouse and field conditions*

Low

night temperature (l+O + 5° F) exposures of young celery
plants had a pronounced influence in hastening the date
and increasing the per cent of seedstalk formation in both
field and greenhouse tests.

A high soil nitrate level

(75 ppm) favored seedstalk growth and development under

Hezekiah Jackson

field conditions, but 100 ppm of soil nitrate under green­
house conditions had an inhibitory effect on the same
responses*
Celery plants which were exposed to low night tempera­
tures and low levels of soil nitrates before transplanting
to the field generally had a greater physiological tolerance
for comparable spray concentrations of maleic hydrazide*
The lethal injuries induced by maleic hydrazide treatments
followed a definite pattern*

Initial injury occurred as

a chlorosis on the inner petioles and leaves, followed by
a discoloration of the older petioles and leaves, and
subsequent death of the plants*
Storage tests with two varieties (Cornell 19 and Utah

1 $) of celery were conducted wherein foliage sprays of
maleic hydrazide (500 , 1000 , and 2500 ppm) were applied
prior to harvest*

The celery which was harvested and sub­

sequently stored at 33 + 2° P for various periods of time
was analyzed for total, reducing, and non-reducing sugars;
and for total and nitrate nitrogen*

No significant alter­

ations in total or nitrate nitrogen were observed.

However,

significant increases and decreases in sugars were char­
acteristic of some of the maleic hydrazide treatments, but
not others, and several Inconsistencies were noted in the
results of the two storage tests*
Tissue analyses of celery petioles harvested from
plants of various ages and grown at 1 0 , 20 , and 75 ppm of
soil nitrate, revealed that foliage sprays of maleic

Hezekiah Jackson

hydrazide of 100 to 250 ppm decreased the soluble nitrogen
content®
The results of the present research concerned with
the effects of maleic hydrazide in the development of celery
plants is discussed in view of the reports of others
relative to the influence of this chemical on the vege­
tative and flowering responses in plants*

It is significant

that as herein reported the formation of seedstalksin
celery plants has been promoted by foliage sprays of maleic
hydrazide even with plants not previously induced to
flower by cold treatments*

ACKNOWLEDGEMENTS *
The author wishes to express sincere appreciation
*

to Dr* Sylvan H* Wittwer for suggesting the research
problem, and for hia guidance throughout the investigation.
Appreciation is also given to other members of the guidance
fc *

'

'

committees Dr. Leo W. Mericle, Dr. Robert L. Carolus, and
Dr. Lloyd M. Turk for their cooperation and advice.
Gratitude is expressed to

Dr. Erwin J.

Benne of the

Agricultural Chemistry Department and members of his staff
for assistance and cooperation in the nitrogen and sugar
analyses.
thanks are given to Dr. William D. Baten of the Michigan
Agricultural Experiment Station for suggestions in designing
the experiments and analyzing and interpreting the data.
Grateful acknowledgements
Davis and Mr. Robert Gellispie

are also due

Dr. John P.

for their cooperation

at

the Michigan State College Muck Experimental Farm on which
plants for the two field experiments were grown.

TABLE OP CONTENTS
Part
I
II

III
IV

Pag©
INTRODUCTION ........................

. . . . . . .

1

REVIEW OP LITERATURE .............................

k

Effect of Plant Growth Substances Other Than
Maleic Hydrazide on Flowering Responses in Plants

!+.

Effect of Maleic Hydrazide on Flowering
Responses in Plants. • • • • • • • • • • • • • •

6

Some Effects of Maleie Hydrazide on Vegetative
Responses in Plants. •

8

Effect of Maleic Hydrazide on the Anatomy
and Morphology of Plants • • • • • • • • • • . .

10

Effect of Maleic Hydrazide on the Chemical
Composition of plants. • •
• • • • • • • • • •

11

STATEMENT OF THE PROBLEM • • • • • • . . . . • . •

13

EXPERIMENTAL • • •

11*.

..............

General • . • • • • . . • • • • • • • • • • • • •

lij.

The Responsej of Celery Plants to Maleic
Hydrazide as Influenced by Nitrate Levels
and Temperature (195»1) • • • • • • • • ♦ • • • •

li|.

The Response of Celery Plants to Maleic
Hydrazide as Affected by Temperature and
Various Times of Application (195>2). • « • • • •

23

The Response of Celery Plants to Maleic
Hydrazide under Greenhouse Conditions as Influenced
by Temperature, Nitrate Levels, and Time of
Application. • • • • • . • • • • • • • • • • • •
$0
The Effect of Maleic Hydrazide Concentrations
on Soluble Nitrogen Content of Maturing Celery
Plants as Influenced by Nitrate Levels and
Temperature. • • • • » • • • • • • • • • • • • •

6ij.

i

TABLE OF CONTENTS

CONT.

Part

V

Pag©
The Effect of Preharvest Sprays of Maleic
Hydrazide on the Sugar and Nitrogen Content
of Two Varieties of Celery as Influenced by
Time in the Field After Spray Applications
and Length of the Storage Period (1951)* • • ♦ *

66

The Effect of Preharvest Sprays of Maleic
Hydrazide on the Sugar Composition of Two
Varieties of Celery Plants as Influenced
by Various Times of Storage (195>2) • « • • • « •

72

GENERAL DISCUSSION

..........

. . .

79

Some Effects of Mgleic Hydrazide on the
Vegetative Growth"of Celery Plants • • • « • • •

79

The Effects of Maleic Hydrazide on
Flowering in Celery Plants • • • * • • • • » • •

82

<

The Influence of Maleic Hydrazide on the
Quality of stored Celery • « • • • • • • » • • •

86

VI

SUMMARY......................................... . •

88

VII

LITERATURE C I T E D ............................. . , .

90

LIST OP FIGURES
Figure
1

2

3

Jj.

5

6

7

8

9

10

Pag©
Th© effects of temperature and low nitrogen
level (10 ppm) on the response of celery
plants to maleic hydrazide • * • » • • • • • • «

19

The effects of temperature and high nitrogen
level (75 ppm) on the response of celery
plants to maleic hydrazide • « « • • • • • • • •

20

Growth of seedstalk initials in "cold induced"
Cornell 19 celery plants as influenced hy
early applications of maleic hydrazide • * • * «

30

Growth of seedstalk initials in "cold" and
"not cold induced" Cornell 19 celery plants
as influenced by early maleic hydrazide
application (May ? ) • • • • » ...........

32

Growth of seedstalk initials in "cold induced"
Cornell 19 celery plants as influenced by
early maleic hydrazide applications* • * • • • • »

33

Growth of celery seedstalk initials In "cold
induced" celery plants as influenced by age
of plants when treated with 100 ppm of
maleic hydrazide • • » * • < > • • • « • « • • • »

3l±

Growth of seedstalk Initials in "cold induced"
Cornell 19 celery plants as Influenced by
increased concentrations of maleic
hydrazide applied June I d • • • « • • » • « • • •

36

The influence of early applications of maleic
hydrazide applied April 23 on the growth and
development of Inflorescences in "not cold
Induced" Cornell 19 celery plantso • « • • • • «

38

The Influence of high concentrations of maleic
hydrazide applied July 2, on the growth and
development of Inflorescences In "cold induced"
Cornell 19 celery plants
..................

39

Comparative response of Cornell 19 celery
plants to various nitrate levels when grown
at 60° F night temperature • • • • » « « « *

52

•»

LIST OP FIGURES

CONT#

Figure
11

12

13

Page
Comparative response of Cornell 19 celery
plants to various nitrate levels when grown
at l±0° F night temperature • • • • • • • • # #

•

5k

100 ppm of maleic hydrazide, 20 ppm of
nitrate, and grown at J4.O F night temperature# •

56

The response of Cornell 19 celery plant to

The response of Cornell 19 celery plant to

100 ppm of maleic hydrazide, 20 ppm of
nitrate, and grown at 70° F night temperature# •

57

LIST OF TABLES
Table
I

II

III

•IV

V

VI

VII

VIII

IX

Page
The effect of various concentrations of maleic
hydrazide and levels of nitrogen on per cent
seedstalk formation in Cornell 19 celery at
various times during the growing season (1951) •

22

The effect of various concentrations of maleic
hydrazide and levels of nitrogen on average
heights of seedstalks developed In Cornell 19
celery at various times during the growing
season (1951)*
............... ..

21*.

Concentrations of maleic hydrazide applied to
Cornell 19 celery with corresponding dates of
application* • • • • • • • • • • • • • • • • • •

26

The effect of twelve dates of application of
maleic hydrazide and two temperatures (ij.0 +
5° P and 65° F) on per cent of plants whieH
had formed seedstalks on August 25, 1952 in
Cornell 19 celery* . o o o * * * * * * * * . * *

in

The influence of twelve dates of application of
maleic hydrgzide and two temperatures (Ij.0 +
5 F and 65 F) on the average height of "~
seedstalks which had formed on August 25*1952
in Cornell 19 celery » » • • • • • » « » • • » •

kZ

The effect of time of application and various
concentrations of maleic hydrazide on per
cent seedstalks which had formed on August 25*
1952 in Cornell 19 celery*

1*

The influence of time of application and
various concentrations of maleic hydrazide on
the average height of seedstalks which had
formed on August 25* 1 9 5 2 .in Cornell 19 celery *

kS

The effect of the interaction of dates x
temperatures x concentrations on per cent
seedstalks which had developed on August 25*
1952 in Cornell 19 celery* • • • « • • • • • • «

k6

The effect of the interaction of dates x
temperatures x concentrations on the average
height of seedstalks which had developed on
August 25* 1952 in Cornell 19 celery • • • • • •

kl

LIST OF TABLES

CONT.

Table
X

XI

XII

XIII

XIV

XV

XVI

XVII

XVIII

Page
Analysis of variance table of per cent seed­
stalks which had formed August 25 s 1952, in
Cornell 19 celery as influenced by tempera­
ture, dates of applications, and concen­
tration of maleic hydrazide* • • • • • • • • • •

1|B

Analysis of variance table of average heights
of seedstalks which had formed August 25*
1952, in Cornell 19 celery as influenced by
temperature, dates of application, and con­
centration of maleic hydrazide • • • « • • • • *

k-9

The effects of maleic hydrazide and tempera­
ture on the final height of seedstalks
developed in Cornell 19 celery (May 17, 1952)# •

56

The effects of dates of application of maleic
hydrazide and temperature on the final height
of seedstalks developed in Cornell 19 celery
(May 17, 1952) * • ..............................

59

The effects of various levels of nitrogen
and temperature on the final height of seed­
stalks developed in Cornell 19 celery
(May 17, 1952) . . . . ..........................

60

Analysis of variance table on the final height
of seedstalks developed in Cornell 19 celery
as influenced by temperature (ij.0o F), nitrates,
dates of application, and maleic hydrazide
concentrations (May 17, 1952)* « • • • • • • • •

61

Analysis of variance table on the final height
of seedstalks developed in Cornell 19 celery
as Influenced by temperature (60 F), nitrates,
dates of application, and maleic hydrazide
concentrations (May 17, 1952)* • • • • • • • • «

62

Analysis of variance table on the final height
of seedstalks developed in Cornell 19 celery
as Influenced by temperature (70 F), nitrates,
dates of application, and maleic hydrazide
concentrations (May 17, 1952)*

63

The effects of various concentrations of maleic
hydrazide and soil nitrate levels on the acetic
acid soluble nitrogen of petioles of Cornell 19
celery at various times during the growing
season (1951)• « « • • • • » • • • • • • • • • •

67

LIST OP TABLES

CONT.

Table
XIX

The influence of preharvest sprays of maleic
hydrazide and storage after treatment on the
per cent sugars (total, reducing, and non­
reducing) in Cornell 19 and Utah 1$ varieties
of celery (1951) • • • • • • • • • ...........

XX

Analysis of variance table on per cent total
sugars in Cornell 19 and Utah 1$ varieties of
celery as influenced by different periods of
storage and various preharvest sprays of
maleic hydrazide (1951)* » • • • • • • • » • • •

XXI

The influence of preharvest sprays of maleic
hydrazide and storage on the per cent nitrogen
(total and nitrate) in Cornell 19 and Utah 1$
varieties of celery (1951) « • * • • * • • • • *

XXII

Analysis of variance table on per cent total
nitrogen in Cornell 19 andUtah 15 varieties
of celery as influenced by different periods
of storage and various preharvest sprays of
maleic hydrazide (1951)* « • • • • • « • • * • •

XXIII

XXIV

•

The influence of preharvest sprays of maleic
hydrazide and storage on the per cent sugars
(total, reducing, and non-reducing) in Cornell
19 and Utah $2-70 varieties of celery (1952) • •
Analysis of variance table on per cent total
sugars in Cornell 19 and Utah $2-70 varieties
of celery as influenced by different periods
of storage and various preharvest sprays of
maleic hydrazide (19$2). • • • • • • » • • • • •

I.

INTRODUCTION

The development of successful methods of controlling
flowering in certain horticultural crops by chemical treat­
ment would be of vast economic importance•

This is likewise

true of many crops other than those classified as horti­
cultural®

The purpose for which a crop Is grown determines

whether or not flowering Is desirable*

Many herbaceous

horticultural crops possess desirable market and edible
qualities in so long as they remain vegetative, and losses
result to farmers when seedstalks develop prematurely.

The

development of varieties which have weaker flowering ten­
dencies; may result in a reduction in vigor, edible and
market qualities, and increase seed production problems.
Certain varieties of celery such as Cornell 19, when
seeded in January and February, and later transplanted to
the field to correspond with commercial practices in Michigan
for the production of early celery, may shoot to seed pre­
maturely*

States Important In celery production such as

Michigan, New York, California, and Florida frequently have
environmental conditions which may cause enormous losses
to celery growers if many of the high qu ility varieties
which usually have strong bolting tendencies are grown.
White and Kennard (67 ) reported that maleic hydrazide
delayed flowering in strawberries and black raspberries

2
with little apparent effect on other plant parts when low
concentrations were applied.

Obviously, if flowering could

be controlled in certain varieties of celery, such as
Cornell 19, with plant growth regulators, this method of
control would be more feasible than resorting to the, control
of flowering by the production of less vigorous, frequently
inferior in quality, non-bolting varieties.

Since the first

reported use of maleic hydrazide as a plant growth substance
in 19i+9 by Schoene and Hoffman (1+8), many investigators as
Fillmore (15), Crafts, Currier, and Day (8), Naylor (i+2, 1+3)*
Moore (1+0), Rood (1+7), Thurlow and Bonner (59), and White
(66), have reported on the control of flowering and fruiting
in different crops by the use of this substance*
The experiments which follow were conducted in the
field and in the greenhouse to determine whether or not
maleic hydrazide would control flowering in Cornell 19
celery, a variety generally accepted as being of high quality
and locally known as Ivory or Golden Pascal.

This high

quality and otherwise acceptable variety is naturally very
susceptible to bolting or premature seeding, when grown
under the usual environmental conditions which prevail in
Michigan during the growth of the early summer crop.
Furthermore, in view of spectacular results with maleic
hydrazide in storage tests with root crops such as onions
and potatoes (69, 71, 72), storage experiments were also
conducted to determine whether or not preharvest foliar
sprays of maleic hydrazide would affect the keeping qualities

i

3
of Cornell 19, Utah l£, and Utah £2-70 varieties of celery
(71).

II.

REVIEW OP LITERATURE

Effect of Plant Growth Substances Other Than Maleic
Hydrazide on Flowering Responses in plants
Effect on flower inhibition*

Dostal and Hosek (13)

were among the first to demonstrate that plant growth
substances can inhibit floral initiation and development
in plants*

Using indoleacetic acid (IAA) applied in lanolin

paste to the leaves of Bripe~to-flowerB shoots of Clrcaea*
they were able to inhibit floral initiation*

Hamner and

Bonner (22) and Thurlow and Bonner (59) applied indoleacetic acid to X anthi urn plants that had been photo-induced
to flower and obtained complete inhibition of flower
initiation*

Their work showed that hormone-like substances

were capable of preventing flower initiation in short-day
plants, even though they had been photoperiodically induced
to flower*

There still remained to be discovered a chemical

means for preventing flowering on long-day, and indeter­
minate or day-neutral plants*

Llverman and Lang (36) have

indicated that a chemical means of preventing flowering in
long-day plants might soon become a reality*
Green and Puller (17)* using indoleacetic acid on
petunia plants, were able not only to prevent further floral
initiation, but also to delay the opening of buds which
had formed previous to the auxin application*

5
Hitchcock and Zimmerman (26) applied potassium alphanaphthalene acetate at concentrations of 200, i|-00, and
800 ppm to apple, cherry, peach, pear, and plum trees*
Flowering and fruiting were delayed depending upon the
concentration of this substance that was applied and the
kind and variety of fruit tree used (20)*

Results from

this work showed that peach and plum trees were more sensi­
tive to a specific concentration of potassium alpha-naphthalene acetate than the other fruit trees*
Wittwer, Coulter and Carolus (68), applied alphaortho-chlorophenoxypropionic acid to celery plants and
observed an inhibition of seedstalk formation*
Effect on flower initiation*

Some of the early work

by Cooper (7)* Clark and Kerns (5)» Traub et al (60), and
Van Overbeek (61, 62, 63 * 6I4.) with the pineapple, showed
that certain plant growth substances were capable of pro­
moting flower initiation*

Clark and Kerns (5) applied

alpha-naphthaleneacetic acid, naphthalene acetamide,
naphthalene-thioacetamide, and a commercial product known
as Fruitone to the pineapple at various concentrations*
Flower initiation was observed depending upon the kind and
concentration of plant growth substance applied*

Cooper (7)

applied naphthaleneacetic acid and ethylene to the pineapple
plant*

Naphthaleneacetic acid was applied as 0*01 per cent

(100 ppm), 0*00$ per cent (50 ppm), and 0*001 per cent (10
ppm) solutions*

Though flower initiation was observed it

was largely dependent upon the plant growth regulator used,

i

6
Its concentration and time of application, and the age of
the pineapple plant (16)•
Hitchcock and Zimmerman (23), working with tomato and
Turkish tobacco plants, and Indoleacetic, indolebutyric,
indolepropionic, naphthaleneacetic, phenylacetic, and
phenylpropionic acids as plant growth substances which were
applied to the soil, observed some floral initiation*

The

extent of floral Initiation was dependent upon the growth
substance used, and its concentration, as well as the age
and species of plant to which the chemicals were applied
(2!*., 25, 70 , 73, 7i*, 75, 76, 77, 78),
Leopold and Thimann (3i|.) have shown as a result of
work with two grasses (Chaleo teosinte and winter barley)
and alpha-naphthalone acetic and indoleacetic acids, that
floral Initiation may be retarded or favored, depending
upon the auxin economy within the me ri stems of the plants*
High auxin levels retarded and low auxin levels favored
floral initiation in these grasses*
Effect of Maleic Hydrazide on H L o w e M n g
Responses in Plants
Reports which have appeared in the literature have
suggested tha maleic hydrazide possesses a number of unique
qualities that are not evident In other generally known
plant growth regulators (1),

Many of the investigations

carried out with maleic hydrazide since 19h9 have had as
their purpose the elucidation of the possibilities which this

7
chemical might possess for controlling flowering in economic
plants*

Results of research work reported thus far have

shown generally that maleic hydrazide inhibited floral
development in a large number of plants on which it has
been applied*
Naylor and Davis (1*4) have shown that maleic hydrazide
applied at concentrations of 0*2 per cent (2000 ppm),
0*4 per cent (4000 ppm), and 0*3 per cent (8000 ppm) killed
blossoms present on Turkish tobacco plants*

When maleic

hydrazide was reduced to 0*1 per cent (1000 ppm) only $0
per cent of the blossoms present on Turkish tobacco plants
were killed*

Naylor and Davis (J4J4.) also observed that

wheh the concentration of maleic hydrazide applied was
reduced to 0*05 per cent (500 ppm) blossoming was not pre­
vented in Turkish tobacco plants, but it was slower than
in the controls*
Naylor (42), working with Turkish tobacco, maize, and
cocklebur (Xanthlum), reported that maleic hydrazide pre­
vented or retarded flowering when applied to the soil or
foliage of such plants*

Higher concentrations of maleic

hydrazide were required to produce the same effect when soil
applications were employed*
On strawberries White (66) used 0*1 per cent (1000 ppm)
and 0*4

cent (4000 ppm) solutions of maleic hydrazide

and delayed flowering for two weeks*

A

8
Some Effects of Maleic Hydrazide on
Vegetative Responses in Plants
Tiie effects of maleic hydrazide on the vegetative
growth of plants are determined largely by the age, and
species of plants treated and the concentration of the
chemical applied (8)*

Compton (6) observed that maleic

hydrazide applied at concentrations above 100 ppm reduced
growth in Pi sum sativum.

At 50 ppm maleic hydrazide had

less effect on the reduction of growth, and no growth
reduction was apparent at 10 ppm,

Compton (6) also ob­

served that the resumption In growth of plants which had
received 100 ppm of maleic hydrazide was mainly in the
shoots rather than the roots,
Currier and Crafts (9) have shown that 0,2 per cent
(2000 ppm) solutions of maleic hydrazide immediately stopped
growth on two-week-old barley plants, but had no apparent
effect on five-week-old Upland cotton.

Young cotton in the

cotyledon stage was seriously injured by maleic hydrazide.
These investigators (9) noted also that the age of the
grasses determined the injury observed from specific con­
centrations of maleic hydrazide.

When maleic hydrazide

was applied in below lethal concentrations, the inhibition
of plant growth was mainly temporary (8, 9, i|.8),
Leopold and Klein (33) employed the slit-pea, pea
straight growth, and the A vena straight growth test to
determine the relation between auxin level within plants
and reduction in growth observed from the application of

9
various concentrations of maleic hydrazide*

It was noted

that maleic hydrazide had a greater inhibitory effect on
plant growth when the natural auxin level was low than when
the natural auxin level was high*

This suggested that

auxins may counteract the action of maleic hydrazide (33)*
Leopold and Klein (33) further concluded that maleic hydra­
zide should be classified as an antiauxin, because its
behavior is similar to other chemicals which are classi­
fied as antiauxins*

Though such compounds as 2,3,5-tri-

iodobenzoid acid, coumarin, 2,JLj.-dichloranisole, transcinnamic acid, and maleic hydrazide are classified as
anti auxins, natural plant auxins have been shown to counter­
act the action of only maleic hydrazide and trans-clnnamlc
acid (33).
Wittwer and Paterson (71) have demonstrated that
maleic hydrazide applied at concentrations of 500 to 2500
ppm to the foliage of mature onions in the field prevented
subsequent sprouting and breakdown in storage*

When maleic

hydrazide was applied at concentrations of 1000 to 2500 ppm
four to six weeks before harvest, sprouting was completely
prevented in Irish Cobble r and Pontiac varieties of potatoes
even when held in storage for seven months at 55° F (37* 71) .
Peterson (ij.6) showed that maleic hydrazide prevented
sucker growth on tobacco plants with no significant effect
on yield, quality, or burning properties.

10
Effect of Maleic Hydrazide on the
Anatomy and Morphology of Plants
A knowledge of the morphological appearance and forma­
tive effects produced by the application of chemical sub­
stances which regulate plant growth is essential before
their use on a large scale is adopted*

Many investigators

have observed changes in the gross appearance of plants
after treatment with maleic hydrazide, but few agree as to
what internal factors are responsible*

Naylor and Davis

(i|4 ) have reported that in many instances maleic hydrazide
treated wheat, sunflower, and Turkish tobacco plants developed
abnormal leaf shapes*

In addition, Naylor and Davis (I4I4.)

observed the following sequential changes in plants after
treatment with maleic hydrazide: (a) loss of apical domin­
ance, (b) expansion of leaves already formed, (c) an inten­
sification of green color, (d) increase in anthocyanln
pigment, and (e) some chlorosis*

The degree of expression

of these characters depended largely upon the concentration
of maleic hydrazide used and age of the plant when treated*
Moore (I4.0 ) noted that maleic hydrazide treated sweet
c o m and garden beet plants developed narrower leaves than
the controls*
Darlington and McLeish (12), studying the action of
maleic hydrazide on cell division in Vicla faba, noticed
that high concentrations of maleic hydrazide, 0*005 M and
above, did not stop mitosis*

However, such concentrations

inhibited cell division for two days*

These investigators

i

11
(12) further observed that concentrations of maleic hydra­
zide at 0*005 M and above induced a large number of break­
ages in the heterochromatic portion of the chromosomes (35*

k$f 65) • It has not as yet been reported as to whether or
not chromosome breakages are responsible for the male
sterility which maleic hydrazide induces in maize, as
reported by Naylor (l|2) •
Greulach and Atchison (19) noted that maleic hydra­
zide inhibits cell division at low concentrations, but not
cell enlargement*

G-reulaoh and Atchison also observed that

high concentrations of maleic hydrazide stopped both cell
division and cell enlargement*
Currier, Day, and Crafts (10) reported that maleic
hydrazide may cause the collapse of the phloem elements*
I

' '

thereby allowing certain elaborated foods to differentially
accumulate in specific parts of the plant*
There are other unique aspects of the actions of maleic
hydrazide which distinguish it from most other plant growth
regulators*

Leopold and Klein (33) noted that maleic

hydrazide stimulated the growth of lateral buds in plants,
which effect differs from the lateral bud inhibition usually
induced by other plant growth regulators*
Effect of Maleic Hydrazide on the
Chemical Composition of Plants
Plant growth substances often cause changes in the
chemical composition of plants (21)*

These changes may be

i

12
direct or Indirect expressions of any one of several responses
such as reduced growth, increased growth, flower bud init­
iation, inhibition of flower bud formation, and an increased
pigmentation of the foliage.

Currier, Day, and Crafts (10)

reported that maleic hydrazide treated young barley plants
showed an increase in fructosan polysaccharides, but the
sugars showed no significant change over the control*
Tatum and Curme (55) reported that maleic hydrazide caused
the accumulation of sugars in young corn plants*

A compari­

son of results obtained from young barley (10) and young
corn plants (55)* would seem to suggest that maleic hydra­
zide has a differential influence on food accumulation
within different plants*
Greulach (18 ) reported that maleic hydrazide treated
tomato plants shewed food accumulation in the stem and
leaves*

The age of the plant should always be considered

when Interpreting the response of plants to maleic hydra­
zide (18 , ijl).
Mcllrath (38 )* working with cotton plants, found that
maleic hydrazide favored the accumulation of carbohydrates
in treated plants compared with controls, while the non­
carbohydrate constituents such as proteins were reduced
by the chemical treatment*

4

III.

STATEMENT OF THE PROBLEM

The numerous accounts which appear in the literature
on the many diverse effects noted for maleic hydrazide as
a plant growth regulator suggest that this chemical, if
used properly, might control the initiation of flower primordia, delay or hasten the expression of symptoms
accompanying the flowering process, and exert a measure of
control over general plant growth.
In the experiments which follow, field, greenhouse,
and storage tests were conducted on a large enough scale
such that the results should give some definite suggestions
as to the possibilities of maleic hydrazide as a plant
growth substance for controlling flowering in celery, and
as a chemical means of promoting the retention of market
and edible quality in the storage celery.

IV,

EXPERIMENTAL
General

The principle parts of these investigations, concerned
with the effects of maleic hydrazide on the growth and
development of celery, included two field plantings, one
in the greenhouse, two.storage experiments, and a series
of fresh tissue analyses of plants started in the green­
house and later transplanted to the field.

The first field

experiment was conducted in 1951 and the second in 1952®
The greenhouse experiment was conducted during the fall
and winter months of 1951-1952,

The storage experiments

were conducted during the fall of 1951 and the summer of
1952®

The fresh tissue analyses were performed on celery

grown during the spring and summer of 1951*
The Response of Celery Plants to Maleic Hydrazide
as Influenced by Nitrate Levels and Temperature (1951)
Methods and procedure.

Plants were started In the

greenhouse and then transplanted to the field.

Seed of

Cornell 19 celery (Stock No, 31562, obtained from FerryMorse Seed Co,, Detroit, Michigan) were sown February 18,
1951* in wooden flats which contained a 50-50 mixture of
steam sterilized muck soil and fine sand®

The flats were

then placed in a 65° F house for germination.

Early it was

15
observed that the celery seed remained in a quiescent
condition for four weeks when placed in an 80-85° F (night
temperature) house, but germinated within a two-week period
when held at 60° P night temperature.

On March 13, four

weeks after germination, the seedlings were transplanted
into flats (three inches apart each way) which contained a
75-25 mixture of steam sterilized muck soil and fine sand,
respectively.

The plants remained at this spacing in the

flats until they were set into the field on May l5«

All

plants were grown in a greenhouse maintained at 65° F
night temperature until May 1,
The experiment was designed to determine, in a general
way, some of the effects of maleic hydrazide, nitrogen,
and temperature on the growth and development of Cornell 19
celery.

Constant levels of phosphorus and potassium were

maintained continuously while the plants were growing in
the flats,

The two nutrients were applied to the soil in

solution form as parts per million (ppm) from chemically
pure nutrient salts.

Potassium was maintained in the soil

solution at 30 ppm and phosphorus at 5 ppm#

Nitrogen, on

the other hand, was maintained at three different levels
in the soil solution: 10, 20, and 75 ppm.

Soil analyses

were made each week to determine the nutrient status of the
soil in the flats and for maintaining the proposed nutrient
levels.

All nutrients were applied weekly to maintain the

above desired levels*
The 30 ppm potassium level was easily maintained with

little further addition of nutrient solution once the desired
It wa 3 very difficult, however, to

level had been obtained.

obtain and maintain the^ desired phosphorus level of 5 ppm.
Several times the required amount of phosphorus was added at
weekly intervals in solution form with little change in
extractable phosphorus.

The difficulty of obtaining the

required phosphorus level suggests high phosphorus fixation
in the soil mixture (39)*

The Spurway system (52) for

determining active soil nutrients was used in all instance3 o
The three nitrogen levels were fairly easily maintained#
On May 1, one-half of all flats, which contained twenty
plants each, were moved from the greenhouse to an adjacent
coldframe for the plants to receive a low temperature (I4.O +
5° P) treatment, and one-half were retained in the green­
house at 65° P night temperature•
Water solutions of the 30 per cent formulation of the
diethanol amine salt of maleic hydrazide (obtained from the
United State Rubber Company, Naugatuck Chemical Division,
Naugatuck, Conn,) were applied to the foliage of the celery
plants also on May 1,

The concentrations of maleic hydra­

zide applied were 25* 50, 100, and 250 ppm#
plants served as controls.

Non-traated

No further application of maleic

hydrazide was made through the duration of the experiment#
All maleic hydrazide concentrations were applied with a
three-gallon knapsack sprayer, using Dreft (one-tenth of
one per cent solution) as a wetting agent#
On May 15* the plants were transplanted to a field of

17
muck soil at the Michigan State College Muck Experimental
P a m ten miles north of East Lansing, Michigan*
A spllt-plot experimental design was utilized in the
field for evaluating the various treatments applied to the
celery plants.

The design consisted of three main blocks

which corresponded to the three different nitrogen levels
(10, 20, and 75 ppm).

Ammonium nitrate, monocalcium phos­

phate, and potassium chloride were used as sources of
nitrogen, phosphorus, and potassium, respectively*

Each

main nitrogen block contained plots of celery plants which
had received four concentrations of maleic hydrazide (25.

50 , 100, and 250 ppm), controls, and two temperatures (ij.0 +
5° P and 65° P) with all possible combinations of these
factors.

The design further consisted to two randomized

replications of each chemical and temperature treatment
within each block.

Twenty plants of a given treatment,

comprising a single plpt, were set six inches apart in
rows that were thirty inches apart and ten feet long.

The

complete design consisted of 1200 celery plants.
One week before the plants were set in the field,
2000 pounds per acre of 0-10-30 fertilizer and 500 pounds
of salt (NaCl) were broadcast and disked into the soil.

On

May 21 and June 12 an additional 1000 pounds per acre of
0-10-30 fertilizer was banded three inches from the plants
and two inches deep.

No effort was made to maintain specific

levels of phosphorus and potassium after the plants had been
transplanted to the field.

However, ammonitun nitrate was

18
banded as described above for phosphorus and potassium at
weekly intervals from May 20 to June 2$ for the purpose of
maintaining to a degree the three (10, 20, and

ppm)

levels of nitrogen.
Results,

Definite morphological differences in celery

pi ants were observed by June 2f>, about 3>£ days after the
application of maleic hydrazide was made.

Figures 1 and 2

show the appearance of representative plants from different
treatments.

The higher the concentrations of maleic hydra­

zide applied, the greater were the morphological effects
produced, and the degree of vegetative growth inhibition.
There was also a difference in effect of maleic hydrazide
on vegetative growth depending upon the nitrate level of the
soil in which the plants were growing and upon previous
temperature treatments.

Plants which had received a low

temperature (lj.0 + $° F) treatment before transplanting to
the field, showed less maleic hydrazide injury than those
which did not receive a low temperature treatment.

It was

also observed that plants grown at high nitrate levels and
treated with high concentrations of maleic hydrazide were
injured to a greater extent than plants grown at low nitrate
levels and similarly treated with high maleic hydrazide
concentrations (Figures 1 and 2),
High concentrations of maleic hydrazide were also
observed to inhibit root growth.

Concentrations which

killed or greatly inhibited vertical growth of the celery
growing points caused an enormous stem enlargement.

This

4

Figure 1.

The effects of temperature and
low nitrogen level (10 ppm) on
the response of celery plants
to maleic hydrazide*

Left;
control, low temperature (40 + £° F)
Center; 2$0 ppm maleic hydrazide, low""tempera­
ture (40 + 5>° F)
Right; 2f?0 ppm maleic hydrazide, high tempera­
ture (65° F)

Figure 2 0

The effects of temperature and
high nitrogen level (7 5 PP*a) on
the response of celery plants to
maleic hydrazide#

Left:
control, low temperature (ij.0 + 5° F)
Center: 250 ppm maleic hydrazide, low”’tempera­
ture (I4.O + 5° F)
Right; 250 ppm maleic hydrazide, high tempera­
ture (65° F)

21
inhibition of vortical stem growth was accompanied in
many Instances by the vigorous sucker growth or laterals.
On June 10, about forty days after the date of maleic
hydrazide application, many of the plants were recovering
from Injury Induced by the high maleic hydrazide treatments.
Thus, to a degree, the inhibition in growth from high con­
centrations of maleic hydrazide was temporary.

Plants

which received a low temperature treatment before trans­
planting to the field recovered to a greater degree than
those which did not receive a low temperature treatment*
Maleic hydrazide, nitrogen, and temperature, separately
and in combination influenced seedstalk development in
Cornell 19 celery (Table I).

The effects of the interaction

of nitrogen and maleic hydrazide on the per cent seedstalk
formation at various dates during the growing season are
given,

how temperature exposure (two weeks in a coldframe

prior to field transplanting) had a positive influence on
seedstalk development, but the differences were not statis­
tically significant.

These data show that as the concen­

tration of maleic hydrazide was increased from

to 100 ppm,

the per cent of seedstalks that formed also increased.

At

25>0 ppm, maleic hydrazide decreased seedstalk development
during the early stages of plant growth.

This was perhaps

because of Injury to the growing tips caused by the high,
somewhat toxic, concentration.

As the plants reached mar­

ketable maturity, those which received a high (2^0 ppm)
concentration of maleic hydrazide showed a greater per cent

TABLE I
THE EPPECT OP VARIOUS CONCENTRATIONS OP MALEIC HYDRAZIDE AND LEVELS OP NITROGEN
ON PER CENT SEEDSTALK FORMATION IN CORNELL 19 CELERY AT VARIOUS TIMES DURING
THE GROWING SEASON (1951)*

Maleic
hydrazide
(ppm)

Dates of observation
NO^ levels (ppm)

July 5
N°3 levels (ppm)

10

20

75

10

20

75

N03
10

20**

1*9

52

22

52

65

25

32

70

1*9

31*

71

5o

1*5

1*2

36

50

100

51*

66

56

250

21

29

3i*.i*

Least differences
necessary for
significance
5% level
19.6

0

Means

1% level

June 21

27.5

July 18
levels (ppm)

August 3
N O -2 levels (ppm)

20

75

10

20

75

21*

52

65

21*

52

65

51*

31*

71

51*

31*

71

51*

1*5

51*

5o

1*5

51*

50

1*5

51*

57

71*

61*

57

70

70

59

70

70

17

56

31

31

71*

61*

1*7

71*

65

59

51.0

1*2.0

1*3.8

51*.6

53.6

1*7.8

60.1*

58.0

1*8.2

60.6

60.1*

28,3

27.2

18 .2

1*0.5

30.2

16. 2

29.8

33.8

16.7

35.7

26.2

39.7

38.2

2$.6

56.8

1*2.1*

22. 7

ifl.8

1*7.3

23.1*

50.1

36.7

*No significant differences were noted between temperatures
Average percentages for four replications
to
to

23
of aee&stalk formation than was evident in earlier periods
of growth*
In a consideration of the means of ail treatments, with
plants grown at the medium nitrate level (20 ppm) there was
a greater percentage of seedstalks formed than at either
the low (10 ppm) or high (75 ppm) nitrate level*

Generally

with plant receiving no chemical treatments (controls) the
percentage of seedstalks increased with an increase in
nitrate level*
Maleic hydrazide not only caused a greater percentage
of seedstalk formation In certain instances, hut also larger
and more extensive inflorescences were observed*

One

hundred parts per million, in most instances, appeared
optimum for seedstalk induction*
Generally those factors which caused a greater per
cent of seedstalk formation also caused an increase in the
average height of Inflorescences borne by the seedstalks*
An exception is noted where the nitrogen level was high*
Table XI gives a statistical evaluation of seedstalk height
measurements*

In general, the heights in relation to

treatment correspond directly to the percentages given in
Table I*
The Response of Celery Plants to Maleic Hydrazide
as Affected by Temperature and Various Times of
Application (1952)
Methods and procedure.

The second field experiment

was designed to determine in a more extensive and in a more

TABLE II
THE EFFECT OF VARIOUS CONCENTRATIONS OF MALEIC HYDRAZIDE AND LEVELS OF NITROGEN
ON AVERAGE HEIGHTS OF SEEDSTALKS DEVELOPED IN CORNELL 19 CELERY AT VARIOUS
TIMES DURING THE GROWING SEASON (1951)
___________
Maleic
k T T r t ' M Q ry *? r t A

June 21
NO 3 levels (ppm)

m

m

10

m

m

Datesofmeasurements

July 5
NO^ levels (ppm)
t

m

r

n

r

n

_______ _

July 18
NO^ levels (ppm)
i n m

20

75

10

20

75____ 10

m m

i

20

m

m

75

August 3
NO 3 levels (ppm)
■

10

20

■

■

i

75

41•

0

1.10

2.75

3.75

1.50

1*.12

6.25

1*.25 10.50 li*.l5

7.62 18.95 23.30

25

1 *65

l*.55

3.80

2.30

6.75

5.90

6.52 16.52 li*.l5

11.65 26.97 21.35

50

2.67

2.50

2.22

3.97

3.77

4.32

10.75 10.12 10.57

18.35 16.97 18.07

100

2.15

3.97

1*.82

2.75

5.95

7.57

8.22 11*. 95 17.37

15.50 25.75 25.77

250

1.05

1.27

0.59

3.40

2.10 •2.07

Means

1.72

3.00

3.60

2.78

lw51*

Least differences
necessary for
significance
5% level
l.Oi*

1.52

2.39

1.69

2.13

3.36

2.38

1% level

1.1*6

8.1*7

19.95 21.12 16.32

5.22

8.01 12.1*3 12.91*

11*.61 21.95 20.96

2.39

3.05

3.26

6.73

6.58

6.10 12.20 11.1*8

3.36

1*.27

i*.58

9.1*3

9.22

8.55 17.10 16.09

Represents average height in inches

10.32 10.Q7

z$

detailed manner some of the physiological responses of
Cornell 19 celery to various concentrations of maleic hydra­
zide applied at different stages of growth as affected by
exposure of the young plants to two temperatures*

Seed

was sown January 13, 1952, in flats which contained the
usual 50-50 mixture of steam sterilized muck soil and fine
sand*

Five weeks after germination on March 21)., the seedlings

were transplanted into flats being set two inches apart
each way, with each flat containing approximately 100
seedlings*

The flats contained the usual growing medium

of a steam sterilized mixture of 75 parts muck and 25 parts
of fine sand®

The plants in all flats were given a weekly

feeding of major and certain minor nutrients to ensure good
growth and maintain uniform nutrient levels for all plants
prior to differential temperature exposure and treatment
with maleic hydrazide*

Four weeks after transplanting to

the flats, weekly application of nutrient solutions were
discontinued*
On May 1, one-half of all flats were placed in an
adjacent coldframe so that the plants might receive a low
night temperature (lf.0 + 5° F) treatment, and the other half
of the flats were left inside the greenhouse at 65° F night
temperature*

Also, at this time, both the inside and out­

side groups of plants were divided into 12 lots to facili­
tate the later application of maleic hydrazide sprays*

The

first spray application of maleic hydrazide was made on
April 16*

(Note Table III for the spray schedule that was

TABLE III
CONCENTRATIONS OP MALEIC HYDRAZIDE APPLIED TO
CORNELL 19 CELERY WITH CORRESPONDING DATES
OP APPLICATION*
Date of
application

Maleic hydrazide concentrations (ppm)

April 16, 1952

0

8

15

25

33

April 23, 1952

0

25

50

75

100

April 30, 1952

0

50

100

200

300

May 7, 1952

0

50

100

200

300

May lij., 1952

0

5o

100

200

400

May 21, 1952

0

50

100

200

400

May 28, 1952

0

5o

100

250

500

June I}., 1952

0

5o .

100

250

500

June 11, 1952

0

100

250

500

1000

June 18, 1952

0

100

250

500

1000

June 25, 1952

0

100

250

500

1000

July 2, 1952

0

100

250

500

1000

*At both temperatures

27
followed throughout the course of this experiment)*
One-twelfth of all plants, including both those which
were placed into the cold-frame to receive a low temperature
treatment and those which remained in the greenhouse, were
i

sprayed with a range of maleic hydrazide solutions weekly*
A three-gallon knapsack sprayer was used to apply the
solutions*

Thus, over a 12-week period, the maleic hydra­

zide spray schedule was completed*

Spray applications

made on April 16, 23* 30, May 7 and li|. were applied to the
plants while they were still in the flats prior to field
transplanting, and those made between May 21 and July 2
inclusive, were applied after the plants had been set into
the field*

The maleic hydrazide spray schedule commenced

with four-inch plants and was completed when the plants
were approximately 1$ inches tall*

The second field experi­

ment was established on the Michigan State College Muck
Experimental Farm in approximately the same location as
the first, (1951), field experiment*
All plants war# set in the field between May 15 and
17*

The soil was well prepared and 2000 pounds of 0-10-30

fertilizer and 500 pounds of salt (Had) were added per
acre as broadcast applications one week before the plants
were transplanted.
The plants were placed according to a field design
consisting of 12 blocks, which corresponded to the 12
different dates of spray applicate (Table H I ) *

Each block

contained forty ten-foot rows and each ten-foot row con-

28
talned twenty, celery plants.

The blocks were further

divided into twenty rows of plants that received low temper-,
ature treatments and twenty rows which did not receive a
low temperature treatment.

Within each temperature group

there were four maleic hydrazide treatments and a control
each of which was replicated four times pertaining to each
block or date of spray application.

Thus a single block

comprised a total of 80 C celery plants and 9600 celery
plants were included in the complete experiment.

Dates of

application, temperature exposures, maleic hydrazide con­
centrations including controls, and replications were
randomized in the design.
Though four maleic hydrazide concentrations and a
control were used on each date of spray application, the
concentrations were increased according to the degree of
plant development.

Thus, the highest concentration of

maleic hydrazide applied on April 16, the first

date of

spray application, when the plants were six inches tall,
was 33 ppm; while the highest concentration applied on the
last date of spray application, July 2, after the plants
had reached a height of approximately lf> Inches, was 1000
ppm.

Therefore, concentrations of maleic hydrazide were

applied in an increasing order based upon age or stage of
development of the plants.

This procedure was deemed

necessary to prevent serious injury to the growing plants
in the younger stages of growth which were found in previous
tests to be very susceptible to injury with maleic hydrazide.

I

29
Results*
a. Relative injury by maleic hydrazide.

About one

month after transplanting the plants to the field, it could
be observed that those plants which received from 200 to
lf.00 ppm of maleic hydrazide during the earlier stages of
growth were beginning to turn yellow, and many of them were
dead about seven weeks following spray application.

As

plants approached maturity the application of maleic hydra­
zide concentrations of 200 to lj.00 ppm was not injurious.
Therefore whether or not a particular concentration of
maleic hydrazide was injurious to vegetative growth, de­
pended largely upon the ^ge of the celery plants at the
time of treatment*
b. Effect of maleic hydrazide on seedstalk initiation*
Randomized samples of whole plants from the different treat­
ments were collected at weekly intervals between July 2 and
August 15> to determine the effect of different concentrations
of maleic hydrazide on seedstalk initiation.

To ascertain

whether or not seedstalk initiation had taken place, all
petioles were removed from the plants to expose the growing
points*

In Figure 3 the seedstalk initials are illustrated

which resulted from maleic hydrazide .application to 13 17-week old celery plants.

Plants represented in Figure 3

received a low temperature treatment before transplanting
to the field.

Maleic hydrazide applied at 100 ppm signifi­

cantly increased seedstalk initiation as compared to non­
treated controls when applied to 17 ” 20-week old celery

Figure 3*

Growth of seedstalk initials in ncold induced" Cornell 19 celery
plants as influenced by early applications of maleic hydrazide*
Top;:

Left,
100ppm
Right,
100ppm
Center: Left,
100ppm
Right,
100ppm
Bottom: Left,
100ppm
Right, control

maleic
maleic
maleic
maleic
maleic

hydrazide
hydrazide
hydrazide
hydrazide
hydrazide

applied
applied
applied
applied
applied

April 23
April 30
May 7
May ll}.
May 21

Photographed July 2, 1952

30

V

fw

31
plants*

Those results were observed on July 2, approxi­

mately ten weeks after maleic hydrazide was applied*
Though maleic hydrazide had a greater effect on seed­
stalk initiation in plants which received a low night
temperature (40 + 5° F) exposure before transplanting to
the field, it also had a significant effect on seedstalk
initiation in those plants which did not receive a low night
temperature (65° F continuously) treatment before trans­
planting to the field.

Figure 4 represents seedstalk

initials of celery plants which did and which did not
receive a cold induction period before they were transplanted
to the field*

It is quite obvious from Figure 4 that

maleic hydrazide at 100 ppm caused seedstalk initiation in
celery plants which had not received a cold induction
period prior to field transplanting.

Concentrations of

maleic hydrazide below 75> ppm were relatively ineffective
in promoting seedstalk initiation in plants which were
approximately 18 weeks old at the time of treatment if they
had not been exposed to low night temperatures before
transplanting to the field*
Age or size of the celery plants at the time of treat­
ment with maleic hydrazide and concentrations of maleic
hydrazide applied were fomid to be very important in affecting
subsequent plant development*

The length of seedstalk

Initials observed were related to the age of the celery
plants and the maleic hydrazide concentrations applied*
Seedstalk initials illustrated in Figures 5 and 6 show that

Growth of seedstalk initials in "cold" and *not cold induced”
Cornell 19 celery plants as influenced.by early maleic hydrazide
application (May 7)•
Top:
cold induced
Bottom: not cold induced
Columns: Left to right, 0, £0,

7$>

and 100 ppm maleic hydrazide
Photographed July 2, 19^2

Figure 5«

Growth of seedstalk initials in ’’cold induced” Cornell 19 celery
plants as influenced by early maleic hydrazide applications.
Top:
May 7
Center: April 30
Bottom: April 23
Columns: Left to right, 0, f>0, and 100 ppm,maleic hydrazide
photographed July 2, 1952

Figure 6 *

Growth of celery seedstalk initials in
"cold induced11 celery plants as influenced
by age of plants when treated with 100 ppm
of maleic hydrazide«
Left column:

Top,
Center,
Bottom,
Right column: Top,
Center,
Bottom,

control
May 21
April 23
May lip
May 7
April 30

Photographed July lip, 195>2

3k

35>
early applications of maleic hydrazide induced bolting
earlier than was observable in the control plants*

This

was true regardless of whether or not the plants had been
exposed to low night temperatures before transplanting to
the field#
c* Effect of maleic hydrazide on seedstalk inhibition.
In direct opposition to the stimulation effects of early
applications of maleic hydrazide on the formation and growth
of seedstalk initials, inhibition of seedstalk elongation
was observed on plants which received high concentrations
(£00 - 1000 ppm) of maleic hydrazide during the later stages
of plant development subsequent to the initiation of flower­
ing, but before bolting was yet evident#
In Figure 7 is illustrated seedstalk initials from
celery plants which received relatively low (100 - 2£0 ppm)
and relatively high (£00 - 1000 ppm) concentrations of
maleic hydrazide applied with respect to the later stages
of growth*

Results of these studies indicated that early

and low concentrations of maleic hydrazide (100 - 2£0 ppm)
Induced seedstalk initiation and elongation while later
and high concentrations (£00 - 1000 ppm) inhibited seed­
stalk elongation*

Celery plants In their early stages of

growth and development cannot usually tolerate concentrations
of maleic hydrazide exceeding 100 ppm*
d* Appearance and development of inflorescences.
Plants which received maleic hydrazide that caused early

i

Figure 7

Growth of seedstalk initials in 11cold induced” Cornell 19 celery
plants as influenced by increased concentrations of maleic
hydrazide applied June l8 „
Left column;

Top,
500 ppm
Bottom, 100 ppm
Right column; Top,
1000 ppm
Center, control
Bottom, 2^0 ppm

maleic hydrazide
maleic hydrazide
maleic hydrazide
maleic hydrazide
Photographed July 28, 1952

37
seedstalk initiation ware generally those on which flower
buds and anthesis could first be observed*

An exception to

this general observation was nbticed on those plants which
received early applications of maleic hydrazide and were not
cold Induced before setting in the field*
Although 100 ppm of maleic hydrazide caused the earliest
observable seedstalk initials In plants which did not
receive a cold Induction exposure before transplanting to
the field, this same concentration caused a retardation in
later floral development*

Inflorescences developed faster

and reached a greater final height on those plants which
received 75 rather than 100 ppm of maleic hydrazide*

The

retardation in the development of seedstalks from 100 ppm
of maleic hydrazide applied in the early growing stages
of celery plants likely resulted from slight injury at
this concentration*

Figure 8 shows from left to right the

effect of 75# 0, and 100 ppm of maleic hydrazide on the
development of Inflorescences on celery plants that did
not receive a cold Induction period*

The absence of

development of inflorescences or seedstalks on celery plants
which received high concentrations of maleic hydrazide (500
and 1000 ppm) applied during
illustrated In Figure 9«

the later stages of growth is

A marked inhibition in vegetative

growth was observed from the

application of 1000 ppm of

maleic hydrazide on July 2*
e* Statistical analyses of data on seedstalk formation.
To determine the variable effects of temperature, concen-

Figure 3

The influence of early applications of maleic hydrazide applied April 23 on
the growth and development of inflorescences in 11not cold induced" Cornell 19
celery plants*
Left to right; 75# 0, and 100 ppm maleic hydrazide

I

Photographed August 15# 1952

u>

°®

igure 9

The Influence of high concentrations of maleic hydrazide applied July 2 , on the
growth and development of Inflorescences in ’’cold induced5* Cornell 19 c elery
plants#
Left to rights 0, 1000, and 500

maleic hydrazide

Photographed August 1 5, 1952

tration, and time of application of maleic hydrazide on
the per cent seedstalk formation in all treatments, each
celery plant was examined for floral initiation*

Infor­

mation on the earliness of seedstalk initiation was more
accurately obtained by collecting randomized samples of
whole plants at weekly intervals from July 2 to August 15
from all treatments*

Data on the per cent seedstalks and

the average height of seedstalks that had formed by August
25 are shown in Tables IV and V, respectively.

There were

significant increases in per cent seedstalks that were
formed on celery plants which received early applications
of maleic hydrazide as compared with those which received
the later applications.

There were also significant in­

creases in bolting percentages in plants which received a
cold induction period before transplanting to the field in
contrast to those which did not receive a cold induction
o
period, but were held at 65 F night temperature until
transplanted to the field.

In all instances, a greater

number of cold induced plants bolted than those which were
not cold induced*
Table V presents the average heights of seedstalks in
plants treated with maleic hydrazide on the various dates*
A definite correlation exists between the per cents of seed­
stalks that were formed and the average heights of the seed­
stalks*

Generally those conditions which caused the highest

percentages of seedstalks also caused the greatest average
heights of these seedstalks.

The average height of seedstalks

was greater from plants which were cold induced and received

TABLE IV
THE EFFECT OP TWELVE DATES OF APPLICATION OF MALEIC HYDRAZIDE AND W O TEMPERATURES
(1+Q + 5° F and 65° F) ON PER CENT OF PLANTS WHICH HAD FORMED SEEDSTALKS ON
“
AUGUST 255 1952 IN CORNELL 19 CELERY
Means

D ates o f a p p lic a t io n
T em pe ratu re

A p r il
16
23

30

7

May
11+
21

June
28

1+

11

18

25

J u ly
2

1+0 + 5 ° F

8 3 .3 5 6ij..5o 6 0 .7 5 5 5 .7 5 5 9 .5 0 6 3 .7 5 6 k .5 o ? 2 ,2 5 ij-8,90 5 i.i|-0 32,00 1+2.25 5 3 .2 8

65° F

3 1 .2 5 6 0 .5 0 1+6,00 31}..00 1+3.5o 5 8 .2 5 6 3 .0 0 5 6 .2 5 1 7 .2 5 31}-.65 1 2 .2 5 1 3 .2 5 3 9 .1 8

Means

5 7 .5 0 6 2 .5 0 5 3 .3 7 1+1+.87 5 1 .5 0 61.00 6 3 .7 5 61}.,25 33.07 1+3.02 2 2 ,1 2 2 7 .7 5 l}-8.73

Least differences necessary for significance
Dates x temperatures;
5$ level - 20,60
If, level - 27,10

TABLE V
THE INFLUENCE OP TWELVE DATES OF APPLICATION OF HALElC HYDRAZIDE AND WO
TEMPERATURES ( l*.0 + 5 ° F and 65° F) ON THE AVERAGE HEIGHT OF
SEEDSTALKS WHICH HAD FORMED ON AUGUST 25, 1952 IN CORNELL 19 CELERY
D ates o f a p p lic a t io n
T em pe ratu re

A p r il
16

1+0 + 5° F

23

30

.

?

May
11+
21

June
28

1+

11

18

2 6 .0 0 23.05 2 0 .9 5 20.1+5 1 5 .3 0 19.1+5 22,50 20,25 11.10 12.90

65° F

6 .9 5 19.05 15.1+5 11.25 10 , 50* 16.70 21.70 1 0 .8 5

Means

16.1+7 21.05 18.15 1 5 .3 5 1 3 .1 5 18.07 22.10 15,55

25

J u ly
2

Means

8 .1 5 1 1 .2 5 17,61+

7 .8 5

2 .1 0

3 .0 0 1 0 .7 2

7 .1 7 1 0 .3 7

5 .1 2

7 .1 2 11+.18

3 .2 5

L e a s t d iff e r e n c e s n e c e s s a ry f o r s ig n if ic a n c e
D ates x te m p e ra tu re s ;
% le v e l
7 .6 ?
1% l e v e l - 1 0 .1 1

ro

43
the early applications of maleic hydrazide*

Celery plants

which were not cold induced and received later applications
of maleic hydrazide produced the least number and the
shortest seedstalks.

With respect to dates of application

and concentrations of maleic hydrazide, a significant inter­
action in percentage of seedstalks formed was noted.

There

was also a significant difference in the average heights
of seedstalks formed based upon the date on which maleic
hydrazide was applied and the concentrations used.

Tables

VI and VII provide data relative to the interaction of dates
on which maleic hydrazide was applied and corresponding
concentrations.

There was also a significant triple inter­

action between dates x temperatures x concentrations for
j

both per cent seedstalk formation and average heights of
observed inflorescences (Tables VIII and IX).
Tables X and XI show that dates, temperatures, and
treatments singly and in combinations had, significant in­
fluences on the percentages of seedstalks formed and the
average seedstalk heights attained.

In Table X, the

analysis of variance table for per cent seedstalk formation,
but not for seedstalk height as shown in Table XI, shows
there was a significant difference
replications.

level) between

The significance of different factors in

Table XI dealing with seedstalk heights corresponds
generally to those shown in Table X.

i

TABLE VI
THE EFFECT OF TIME OF APPLICATION AND VARIOUS CONCENTRATIONS OF MALEIC HYDRAZIDE
ON PER CENT SEEDSTALKS WHICH HAD FORMED ON AUGUST 25, 1952 IN CORNELL 19 CELERY
■

D ates o f a p p lic a t io n
Concen­
t r a tio n

A c r il
16
23

30

7

May
111
21

„
J u ly

June
28

1|

11

18

25

Means

2

0

i|3 .3 7 4 1 .2 5 61.87 3 3 .1 2 28,12 6 7 .5 0 68.12 5 7 .5 0 2 7 .5 0 2 6 .3 7 26.87 4 1 .2 5 4 3 .5 7

1

5 3 .1 2 58.12 7 9 .3 7 88.12 68.12 80.00 8 1 .2 5 62,50 42 , 5o 7 1 .2 5 40,00 5 1 .2 5 6 5 .0 5

2

5 3 .7 5 7 1 .2 5 73*12 7 1 .8 7 7 5 .6 2 7 8 .7 5 82.50 65.00 50.62 1*8.75 3 5 .6 2 4 3 .7 5 6 2 .5 5

3

61|.37 7 9 .3 7 2 9 .3 7 21|.37 i|6 .8 7 65.62 7 5 .6 2 7 3 .7 5 1*1.25 4 3 .7 5

7 .5 0

2 .5 0 4 6 .9 5

4

68.12 6 2 .5 0 23.12

0 ,6 2

0,00 2 6 .2 7

Means

6.87 3 8 .7 5 1 3 .1 2 1 1 .2 5 6 2 .5 0

3.50 25.00

57.51| 6 2 .!|9 5 3 .3 7 4 4 .8 7 5 1 .4 9 6 0 .9 9 6 3 .7 l| 61|.25 33.07 4 3 .0 2 2 2 .1 2 2 7 .7 5 48.87

L e a s t d if f e r e n c e s n e c e s s a ry f o r s ig n if ic a n c e
D ates x c o n c e n tra tio n s ?
$% l e v e l 2 0 .6 0
1% l e v e l 27.10

TABLE VII
THE INFLUENCE OF TIME OF APPLICATION AND VARIOUS CONCENTRATIONS OF MALEIC
HYDRAZIDE ON THE AVERAGE HEIGHT OF SEEDSTALKS WHICH HAD FORMED ON
AUGUST 2f>, 1952 IN CORNELL 19 CELERY

ConcenTrjLStT/XOZX

A p r il
16
23

30

7

D ates o f a p p lic a lb io n
May
28
14
21
4

June

J u ly
2

Means

11

18

7 .1 2

5 .7 5

7 .7 5 1 0 .7 5 11.24

25

0

1 2 .6 2 1 0 .6 2 1 4 .7 5

1

1 5 .2 5 1 6 .1 2 3 0 .7 5 3 5 .7 5 1 9 .6 2 2 4 .3 7 2 6 .2 5 1 5 .3 7

9 .8 7 1 7 .3 5

9 .7 5 1 3 .7 5 1 9 .5 2

2

1 4 .3 7 23.00 2 9 .2 5 25.87 1 9 .3 7 2 3 .6 2 3 0 ,6 2 1 4 .7 5 1 1 .1 2 13.00

7 .0 0 1 0 .6 2 1 8 .5 4

3

1 9 .0 0 3 0 .3 7

9 .8 7

8 .2 5 1 1 .3 7 2 1 .0 0 2 6 ,7 5 2 0 .3 7

7 .1 2 1 0 .6 2

1 ,0 0

0 .5 0 1 3 .8 5

4

2 1 .1 2 2 5 .1 2

6 .1 2

1 .8 7

0 ,6 2

5 .1 2

0 ,1 2

0,00

7 .1 7 1 0 .3 6

5 .1 2

7.12 1 4 .1 7

Means

7 .5 0

6 .7 5 18.62 20.50 12,25

8 ,6 2

2 .7 5

6 ,3 7 1 5 .0 0

1 6 .^ 7 2 1 . Oii- 18.14 1 5 .8 4 1 3 .1 4 18,07 2 2 .0 9 1 5 .5 4

7 .7 3

L e a s t d iff e r e n c e s n e c e s s a ry f o r s ig n if ic a n c e
D ates x c o n c e n tr a tio n s ;
% le v e l 7.67
1% le v e l 10 .1 1

jpfvan

TABLE VIII
THE EFFECT OF THE INTERACTION OF DATES X TEMPERATURES X CONCENTRATIONS ON PER CENT
SEEDSTALKS WHICH HAD DEVELOPED ON AUGUST 25, 1952, IN CORNELL 19 CELERY

Temper­ Concen­
ature tration

April
16

40 +

Dat«3s of applic?vtion
May

23

30

7

14

21

2.8

4

Means
June
11

18

July
25

O

0

7 0 .5 0 ij.6 .2 5 61.25 4 1 .2 5 4 6 ,2 5 6 2 .5 0 6 6 .2 5 6 8 ,7 5 4 7 .5 0 4 3 .7 5 4 5 .0 0 6 1 .2 5 5 5 .0 4

1

8 6 .2 5 6 2 .2 5 7 8 ,7 5 9 7 .5 0 77.50 7 6 .2 5 9 2 ,5 0 6 1 ,2 5 5 2 .5 0 7 8 ,7 5 52.50 7 2 .5 0 74 • 04

2

8 2 .5 0 7 8 .7 5 6 7 .5 0 8 3 .7 5 83.75 7 3 .7 5 70.00 7 0 .0 0 8 1 .2 5 6 2 .5 0 5 3 .7 5 7 2 .7 0 7 3 .7 6

3

9 0 .0 0 7 3 .7 5 5 3 .7 5 4 2 .5 0 4 6 .2 5 8 5 .0 0 7 1 .2 5 8 0 *0 0 5 8 .7 5 6 0 .0 0

7.50

5.00 5 6 .1 2

4

9 0 .0 0 6 1 ,2 5 4 2 .5 0 1 3 .7 5 4 3 .7 5 16,25 22,50 8 1 ,2 5

1.25

0,00 3 3 .9 2

5° F

Means
65° F

4 .5 0 3 0 .0 0

8 3 .8 5 6 4 ,4 5 6 0 .7 5 5 5 .7 5 59.50 6 3 .7 5 64«50 7 2 .2 5 4 8 .9 0 5 5 .0 0 32,00 42.29 5 8 ,5 7

0

1 6 .2 5 3 4 .2 5 6 2 .5 0 2 5 ,0 0 1 0 ,0 0 7 2 ,5 0 70.00 4 6 .2 5

1

3 0 .0 0 5 3 .7 5 8 0 ,0 0 7 8 .7 5 5 8 .? c 8 3 .7 5 7 0 .0 0 6 3 .7 5 3 2 .5 0 6 3 .7 5 27.50 30.00 5 6 ,0 3

2

2 5 .0 0 6 3 .7 5 7 8 ,7 5 60.00 67.50 7 8 ,7 5 9 5 .0 0 6 0 .0 0 2 0 .0 0 3 5 .0 0 1 7 .5 0 15.00 5 1 .3 4

3

3 8 .7 5 8 5 .0 0

5 ,0 0

6 .2 5 47.50 46.50 80.00 6 7 .5 0 2 3 .7 5 2 7 .5 0

7 .5 0

0.00 3 6 .2 7

4

4 6 .2 5 6 3 .7 5

3 .7 5

0 ,0 0 3 3 .7 5 10.00

0.00

0.00 1 8 .6 4

Means

0 .0 0 4 3 .7 5

7 .5 0

9 .0 0

2.50 2 0 .0 0

8 .7 5 21.25 3 1 .9 3

3 1 .2 5 60.10 46.00 34.00 4 3 ,4 9 5 8 .3 0 63.00 5 6 .2 5 1 7 .2 5 3 1 .0 5 12.25 13.25 3 8 .8 4

Least differences necessary for significance
Dates x Temperatures x Concentrations:
5^ level - 20,60
1% level - 27.10

TABLE IX
THE EFFECT OF THE INTERACTION OF DATES X TEMPERATURES X CONCENTRATIONS ON THE
AVERAGE HEIGHT OF SEEDSTALKS WHICH HAD DEVELOPED AUGUST 25, 1952, IN CORNELL 19 CELERY

Dates of application
Temper­ Concen­
ature
tration
16
40 +
5° F

23

30

7

14

21

28

4

June
18
11

9 .7 5 1 1 .2 5 1 7 .5 0 1 9 .7 5 17.50 1 2 .0 0

25

July
2

9 .7 5 1 3 .5 0 1 7 .0 0 1 4 .8 9

0

22,00 1 2 ,7 5 16.00

1

21*., 00 1 9 .2 5 3 0 .2 5 42,00 24.00 2 2 .5 0 3 1 .0 0 20.25 1 3 .7 5 1 8 .5 0 1 4 .7 5 1 7 .5 0 2 3 .1 4

2

2 3 .7 5 2 8 .5 0 2 8 ,2 5 3 1 .5 0 2 2 ,2 5 25.00 2 5 .0 0 18.50 1 9 .0 0 1 5 .7 5 1 1 ,0 0 1 7 .7 5 2 2 .1 9

3

30,00 3 0 .2 5 1 8 .5 0 15.25 1 1 .0 0 2 3 .5 0 24.00 24.50 1 0 ,0 0 1 4 .2 5

1,25

1 .0 0 1 7 .3 7

4

3 0 .2 5 2 4 .5 0 1 1 .2 5

0,25

0 .0 0 1 0 .3 7

Means
65° F

May

April

Means

3 .7 5 10.50

3 .7 5 1 2 ,7 5 20,50

0 ,7 5

6 .2 5

2 6 ,0 0 2 3 .0 5 2 0 .8 5 2 0 .4 5 1 5 .8 0 1 9 .4 5 2 2 ,5 0 20,25 1 1 .1 0 1 2 .9 0

0

3 .2 5

1

8 .5 0 1 3 .5 0

7 .9 5 10.65 1 7 .5 9

1 .7 5

2 .0 0

4 .5 0

6 .2 5 1 3 .0 0 3 1 .2 5 2 9 .5 0 1 5 .2 5 2 6 .2 5 2 1 ,5 0 10,50

6 .0 0 1 6 .2 5

4.75

7.00 1 5 .6 2

2

5.00 1 7 .5 0 3 0 .2 5 2 0 ,2 5 1 6 .5 0 2 2 .2 5 3 6 .2 5 11.00

3 .2 5 1 0 .2 5

3.00

3 .5 o 1 4 .9 1

3

8.00 3 0 .5 0

1 .2 5

1 .2 5 1 1 .7 5 1 3 .5 0 2 9 .5 0 16.25

4 .2 5

7 .0 0

0 .7 5

0.00 1 0 .3 3

4

12.00 2 5 .7 5

1 .0 0

0.00

9.50

0 .5 0

4 .0 0

0 .0 0

0.00

6.90 1 9 .0 5 1 5 .4 5 1 1 .2 5 1 0 .5 0 16.70 21.70 1 0 .8 5

3 .2 5

7 .8 5

2 .1 0

3 .0 0 10.71

Means

5 .2 5

2 .2 5 1 9 .7 5 2 1 .2 5

6 .7 5

1 .7 5

L e a s t d iff e r e n c e s n e c e s s a ry f o r s ig n if ic a n c e
Dates x T em pe ratu re s x C o n c e n tra tio n s :
5$ l e v e l 7 .6 7
1% le v e l - 1 0 ,1 1

0 .0 0

7.00

2,25

7 .6 0

5 .1 0

TABLE X
ANALYSIS OP VARIANCE TABLE OP PER CENT SEEDSTALKS WHICH HAD
FORMED AUGUST 25 , 1 9 5 2 , IN CORNELL 19 CELERY AS INFLUENCED
BY TEMPERATURE, DATES OP APPLICATIONS, AND
CONCENTRATION OP MALEIC HYDRAZIDE
S ource o f v a r ia n c e

D egrees o f
fre e d o m

T o t a l sum
o f sq u a re s

Mean
sq u a re s

P

T o ta l

479

4 6 4 ,4 3 1

D ates

11

94 ,16 6

8 ,5 6 0

3

2 ,0 9 5

698

3 .2 *

33

1 2 ,7 3 1

38?

lo 7 NS

1

4 3 ,7 9 7

4 3 ,7 9 7

2 0 0 .9 * *

11

2 1 ,51 6

1 ,9 5 6

80 9 “ '*

4

9 5 ,4 6 4

2 3 ,8 6 6

1 0 9 .4 * *

44

89,934

2 ,0 4 3

9 .3 '"*

4

1,694

423

1 .9 NS

1(4

32,249

733

■3 0-3H53«3

324

70,735

218

R e p lic a t io n

Replication x Dates
Temperature
Temperature x Dates
Concentration
Concentration x Dates
C o n c e n tr a tio n x
T e m p e ra tu re
C o n c e n tr a tio n x D a te s
x T e m p e ra tu re
E rro r

ghly significant (1% level)
^Significant
{$% level)
NS Not significant

39o2* *

TABLE XI
ANALYSIS OP VARIANCE TABLE OP AVERAGE HEIGHTS OP SEEDSTALKS
WHICH HAD FORMED AUGUST 2 5 , 1952, IN CORNELL 19 CELERY
AS INFLUENCED BY TEMPERATURE, DATES OP APPLICATION,
AND CONCENTRATION OP MALEIC HYDRAZIDE
Source o f v a r ia n c e

D egrees o f
fre e d o m

T o t a l sum
o f sq u a re s

Mean
■sq u a re s

P

T o ta l

i+79

59,791}.

D ates

11

1 3 ,8 8 7

1 ,2 6 2

3

129

k3

1 . 4 NS

33

1 ,2 9 5

39

1 .3 NS

1

5 ,7 1 2

5 ,7 1 2

1 8 4 .3 * *

216

6 .9 * *

R e p lic a t io n
R e p lic a t io n x D ates
T e m p e ra tu re
T e m p e ra tu re x D ates
C o n c e n tr a tio n
C o n c e n tr a tio n x D ates
C o n c e n tr a tio n x
T e m p e ra tu re
C o n c e n tr a tio n x D ates
x T e m p e ra tu re
E rro r

11

2 ,3 7 9

4 0 .7

•SH'r

4

9 ,3 9 0

2 ,3 1 0

7 5 .7 * *

44

1 3 , 6ii-5

310

1 0 .0 * *

4

131

33

1 .0 NS

kk

3 ,1 5 6

72

2 .3 * *

32k

1 0 ,0 6 0

31

H ig h ly s i g n i f i c a n t {~L% l e v e l )
NS N o t s i g n i f i c a n t

So
The Response of Celery Plants to Maleic Hydrazide under
Greenhouse Conditions as Influenced by Temperature,
Nitrate Levels, and Time of Application
Methods and procedure*

The greenhouse experiment was

designed to study under controlled conditions of temperature
and nutritional levels of nitrogen some physiological responses
of Cornell 19 celery to maleic hydrazide.

Seeds were planted

August 25# 19Sl» and final records of the plants were made
on May 17# 1952*

Procedures used in seeding, early care

of the plants, and the application of maleic hydrazide
were similar to those already described for the field
experiments.

The seedlings were transplanted individually

on October 20, 195>1# into standard eight-inch clay pots
containing a 75>-25 mixture of steam sterilized muck soil
and fine sand, respectively*
A total of 321+. potted plants were divided into three
different groups of 108 plants each.

The groups were

placed Into separate greenhouses, and each greenhouse was
maintained at a different night temperature.
temperatures selected were I4.0 , 60, and 70° P.

The night
All green­

house temperatures designated are night temperatures.

The

plants in each greenhouse were grown at three different
nitrogen levels: 10, 20, and 100 ppm.

Phosphorus was

maintained at a constant level of $ ppm and potassium at a
constant level of 30 ppm.
6.5.

The pH was maintained at about

Maleic hydrazide was applied at $0 and 100 ppm.

Nutrient levels were maintained as described for the first

5i

field experiment ($2 )#

Non-treated lots of plants comprised

control comparisons for each temperature, nitrogen level,
and maleic hydrazide concentration.

To obtain some infor­

mation on the effect of age of the plants and maleic
hydrazide concentrations applied, one-third of the plants
were sprayed November 17* a second third December 10, and
the remainder on December 30* 1951*
For the purpose of observing responses of 26-week old
celery plants to temperatures different from those at which
they had been growing for 22 weeks, a transfer of all plants
to a different temperature wa 3 made on March 21, 1952*

At

the time of this transfer, no evidence of seedstalk formation
was observable.

Plants which had been growing in a ij.0o F

house were transferred to a 70° F house; and those which
had been growing in a 70° F house were transferred to a
i|.0° F house.

The plants which had been growing in a 60° F

house were transferred to a $0° F house*
Weekly measurements (in inches) were taken from April

5 to May 17* 19i?2, of the seedstalks that formed#
Results# Temperature had a'pronounced effect on the
vegetative growth of celery plants#

Plants grown in the

ij.0° F house were dwarfed and generally stunted.

Those

grown in the 60° F house maintained desirable vegetative
growth#

At 70° F most of the plants grew very rapidly and

formed long, slender petioles.

In Figure 10, from left to

right, are illustrated representative plants which were

sure 10#

Comparative response of Cornell 19 celery plants to various nitrate levels
when grown at 60° F night temperature#
Left to right: ICO, 20, and 1C pom nitrates
photographed January 5, 19p2

vn
M

grown in the 60 ° P house at 100 , 20 , and 10 ppm of soil
nitrates, respectively.

The most desirable plants produced

were those which received 20 ppm of nitrates and were grown
at 63° P.

It can be seen also from Figure 10 that both 10

and 100 ppm of nitrates had inhibitory effects on vegetative
growth.
Figure 11 shows the effect of low temperature (lf0° P)
and various soil nitrate levels on vegetative growth in
celery plants.

Plant growth was inhibited at l|.0o P

regardless of the nitrate levels used.

A comparison of

plants in Figures 10 and 11 will show that at 60° P, 100
ppm of nitrates produced a larger plant than 10 ppm of
nitrates.

Whereas at J4.O0 P, a larger plant was produced

with 10 ppm of nitrates than with 100 ppm of nitrates.
This difference in growth would suggest that at ij.0° P

100 ppm of nitrates was toxic, thereby inhibiting vegetative
growth.

At 60° P, conditions for physiological activities

of the plant were favored over those at 1^.0° P for plant
growth.

This led to the absorption and utilization of

more soil nitrates which was manifested in Increased vege­
tative growth.
At 70° P, the growth of the plants was proportional
to the soil nitrate levels, being smallest at the lowest
nitrate level (10 ppm) and largest at the highest nitrate
level (100 ppm).

This growth pattern would seem to indicate

that at 70 ° p environmental conditions for plant growth were
such that additional soil nitrates caused increased vegetative
growth.

igure 1

Comparative resp on se of Cornell 19 c e le r y plants to various nitrate levels
when grown at J4.O0 F night temperature*
Left to right: 100, 20, and 10 ppm of nitrates
photographed Janua rvJ

Maleic hydrazide also had a pronounced effect on mor­
phology and vegetative growth of the celery plants*

The

effects were related in many respects to the temperatures
at which the plants were growing and the soil nitrate levels*
Figures 12 and 13 show the comparative effects of 100 ppm
of maleic hydrazide on celery plants when grown at low and
high temperatures, respectively*.

One of the most obvious

effects observed, of maleic hydrazide on young celery plants,
was the production of a chlorotlc condition especially near
the growing points, and an enlargement of the stem*

Stem

enlargement was greatest at high temperature and high nitrate
level*

Death of the growing points occurred in many in­

stances prior to stem enlargement*

At low temperature this

chlorotie condition was confined mostly to the young pet­
ioles*

The chlorosis, however, was observed even on the

older petioles of plants which were grown at 70° F*
Measurements taken of the seedstalks were statistically
analyzed to compare the influence of the three levels of
soil nitrates, maleic hydrazide concentrations, and the
dates of maleic hydrazide application, on the final average
height of the seedstalks*

Data represented by Tables XTI

to XVII apply only to measurements taken May 17, 1952*
Transferring of plants from the lj.0° F house to the 70° F
on March 21 caused a rapid elongation of the seedstalks
which were not visible prior to the transfer*

Very little

effect on seedstalk elongation, however, was observed by
the transfer of plants from the 70° F to the ij.0° F house

F ig u r e 1 2 .

The re s p o n s e o f C o r n e ll 19
c e le r y p l a n t to 100 ppm o f
m a le ic h y d r a z id e , 20 ppm o f
n i t r a t e , and grown a t I4.O0 F
n ig h t te m p e ra tu re .
P h o to g ra p h e d J a n u a ry 5» 19^2

F ig u r e 1 3 *

The re sp o n se o f C o r n e ll 19
c e le r y p la n t t o 100 ppm o f
m a le ic h y d r a z id e , 20 ppm
o f n i t r a t e , and grown a t
70 ° F n ig h t te m p e ra tu re *
p h o to g ra p h e d J a n u a ry 5, 1952

TABLE XII
THE EFFECTS OF MALEIC HYDRAZIDE AND TEMPERATURE ON
THE FINAL HEIGHT OF SEEDSTALKS DEVELOPED IN
CORNELL 19 CELERY (MAY 17, 1952)
In c h e s

4^
o
o

H e ig h t o f s e e d s ta lk s i n
60 ° F

(L
o
o

M a le ic
h y d r a z id e
(ppm)

Means

0

3 9 .8 3

1 9 .7 0

llf.elj.0

21}.. 61}.

50

3 8 .5 0

1 8 ,7 0

1 5 .2 0

21}..13

100

3 6 .1 9

1 7 .9 0

Means

3 8 .1 7

l8 ,i|l

2 2 .8 3
lil.6 6

Least differences necessary for significance
Concentration x Temperature;
% level
1jo level
lf0 ° F
60° F
70 ° F

1 .9 3
1 .6 2
1 .8 0

2 .5 6
2 .ll|
2 .3 9

2 3 .8 6

THE EFFECTS OF DATES OF APPLICATION OF MALEIC HYDRAZIDE
AND TEMPERATURE ON THE FINAL HEIGHT OF SEEDSTALKS
DEVELOPED IN CORNELL 19 CELERY (MAY 1?, 1952)

k.0° F

60° F

0
0

r-

H e ig h t o f s e e d s ta lk s i n in c h e s

D ates o f
a p p l ic a t i o n

Means

November 17 # 1951

3 9 .7 2

2 1 .2 5

1 5 .4 6

2 5 .4 7

December 1 0 , 1951

40.34

2 0 .2 7

14.67

2 5 .0 9

December 30# 1951

34*65

1 4 .9 2

13.93

2 1 .1 6

3 8 .2 3

18.81

14.68

2 3 .9 0

Means

L e a s t d if f e r e n c e s n e c e s s a ry f o r s ig n if ic a n c e
D ates o f a p p l ic a t i o n x T e m p e ra tu re ;
S% l e v e l
1% l e v e l
40° F
lo 9 3
2 .5 6
60° F
1 .6 2
2 .H 4.
70 ° F
1 .8 0
2 .3 9

I

TABLE XIV
THE EFFECTS OF VARIOUS LEVELS OF NITROGEN AHD
TEMPERATURE OF TER FINAL HEIGHT OF SEEDSTALKS
DEVELOPED IN CORNELL 19 CELERY (MAY 17, 1952)
H e ig h t o f s e e d s ta lk s i n

in c h e s

0
0

3 9 .3 4

26.54

14.00

26.62

3 8 ,9 2

1 5 .5 3

1 4 .2 5

2 2 .9 0

100 ppm

3 6 .4 5

14 *4 6

1 5 .7 1

22.20

3 8 .2 3

18,84

1 4 *6 5

2 3 .9 0

25 ppm

no3

-

o
&

10 ppm

i

Means

i

60° F

o

1|0° F

r—

N itr o g e n
c o n c e n tr a tio n s

Means

Least differences necessary for significance
Nitrogen x Temperature:
Si level
1% level
lj.0o F
60° F
70° F

1 .9 3
1 .6 2
1 .8 0

2 .5 6
2 .1 4
2 .3 9

61

TABLE XV
ANALYSIS OP VARIANCE TABLE ON THE PINAL- HEIGHT OF SEEDSTALKS
DEVELOPED IN CORNELL 19 CELERY AS INFLUENCED BY TEMPERATURE
(1+0° P ) , NITRATES, DATES OP APPLICATION, AND MALEIC
HYDRAZIDE CONCENTRATIONS (MAY 1 ? , 1952)
S ource o f v a ria n c e

D egrees o f
fre e d o m

Mean
sq u a re s

p

107

3098

R e p lic a t io n s

3

1+2

ll+ .O

N itr a te s

2

175

8 7 .5

5 .2 * *

D ates

2:

693

31+8 e5

2 0 .5 * *

C o n c e n tr a tio n s

2

ro
£

T o ta l

T o t a l sum
o f sq u a re s

1 2 2 .0

D ates x C o n c e n tra tio n s

1+

337

D ates x N i t r a t e s

1+

£5

N itr a te s x
C o n c e n tr a tio n s

1+

115

28.7

N i t r a t e s x D a te s x
C o n c e n tr a tio n s

8

121

15.1

78

1319

16.9

E rro r

H ig h ly s i g n i f i c a n t (1 % level)
NS N o t s i g n i f i c a n t

81+.3
a

|

mm mm

7 .2
1+.98*'*
mm mm

1 .7 NS

62

TABLE XVI
ANALYSIS OP VARIANCE TABLE ON THE PINAL HEIGHT OP SEEDSTALKS
DEVELOPED IN CORNELL 19 CELERY AS INFLUENCED BY TEMPERATURE
(6 0 ° P ) , NITRATES, DATES OF APPLICATION, AND MALEIC
HYDRAZIDE CONCENTRATIONS (MAY 1 7 , 1952)
D egrees o f
fre e d o m

T o t a l sum
o f sq u a re s

107

8498

R e p lic a t io n s

3

11

3 .7

N itr a te s

2

3257

16 28*9

136 . 88* *

D ates

2

814

40 7*2

3 4 .2 1 * *

C o n c e n tr a tio n s

2

53

2 6 *9

2 .2 6 NS

If.

337

8 4 .4

7 .0 9 * *

D a te s x N i t r a t e s

4

21+70

617.7

5 1 .9 0 ^

N itr a te s x
C o n c e n tr a tio n s

k

87

21.9

l.S If- NS

N i t r a t e s x D a te s x
C o n c e n tr a tio n s

8

535

6 6 .9

5 .6 2 * *

78

929

1 1 .9

S ource o f v a r ia n c e

T o ta l

D a te s x C o n c e n tra tio n s

E rro r

*** H ig h ly s i g n i f i c a n t (1% le v e l )
NS N o t s i g n i f i c a n t

Mean
sq u a re s

P

0 .3 1 NS

63

TABLE XVII
ANALYSIS OF VARIANCE TABLE ON.THE FINAL HEIGHT OP SEEDSTALKS
DEVELOPED IN CORNELL 19 CELERY AS INFLUENCED BY TEMPERATURE
(7 0 ° P ) , NITRATES, DATES OP APPLICATION, AND MALEIC
HYDRAZIDE CONCENTRATIONS (MAY 1 7 , 1952)
D egrees o f
free do m

T o t a l sum
o f squ are s

107

1591

R e p lic a t io n s

3

53

17.6

1.1 NS

N itr a te s

2’

64

32.0

2.2 NS

D ates

2

38

1 9 .0

1 .3 NS

C o n c e n tr a tio n s

2

14

7 .0

D a te s x C o n c e n tr a tio n s

4

.105

26.3

CO
*
iH

D a te s x N i t r a t e s

4

87

2 1 .7

1 .5 NS

N itr a te s x
C o n c e n tr a tio n s

4

15

3 .7

N i t r a t e s x D a te s x
C o n c e n tr a tio n s

8

69

8.6

78

1146

1 4 .7

S ource c.f v a r ia n c e

T o ta l

E rro r

NS Not significant

Mean
sq u a re s

, P .

—

--

NS

%
and the 60° P house to the $0° P house.
Maleic hydrazide had a decided effect on the final
average height of seedstalk observed, depending largely
upon temperature, nitrate level, and date of application.
The seedstalks attained a greater final height where the
soil nitrate level was low and also in the case of the low
temperature (l|.0o P) exposure (Table XXV).

Seedstalks were

generally taller where maleic hydrazide was applied at 50
ppm and at the earlier dates (Table XIIX).

Maleic hydra-

zide alone seemed to have had very little effect on final
seedstalk height as compared with nitrogen and temperature.
Plants grown at 1|X)° P were the earliest in bolting and
showed the greatest percentage of bolting.
Generally those plants which received the earliest
applications of maleic hydrazide produced the tallest seed­
stalks.

The effects of time of application of maleic

hydrazide and temperature on the height of the seedstalks
are given in Table XIII.

The seedstalks were tallest on

plants that had been exposed to the ij.0° P temperature and
when maleic hydrazide was applied at the earliest date.
The Effect of Maleic Hydrazide Concentrations on
Soluble Nitrogen Content of Maturing Celery
Plants as Influenced by Nitrate Levels and Temperature
Methods and procedure.

This experiment was undertaken

to ascertain whether different maleic hydrazide concentra­
tions applied to celery plants grown at different temperatures
and soil nitrate levels would affect the soluble nitrogen

65
content of celery during different stages of growth up to
the time of market maturity*

Plants (Cornell 19) for this

experiment were selected from the split-plot design described
under the first, (1951)> field experiment.

On June 15*

July 10, and August 3, 1951* samples of fresh petioles were
collected for nitrogen determinations*

The outer and more

mature petioles were selected in all instances.

Five

plants were taken at random from each of the four repli­
cations and all treatments including controls, in order
that the results of the chemical analysis could be statis­
tically evaluated.
For obtaining samples for chemical analysis, threeinch sections were taken from outer petioles and then diced
into 2 m m pieces.

The section of petiole taken for analysis

was the portion beginning one inch below the base of the
origin of the first leaves, and extending three inches
downward.

The 2 mm pieces of plant material from each

replication and treatment were then thoroughly mixed from
which preparation a five-gram aliquot was sampled.
Further procedures used in obtaining uniform samples
for chemical analyses were according to the methods des­
cribed by Carolus (2),
Results,

The parts per million of soluble nitrogen

(nitrate nitrogen and other nitrogenous compounds obtained
from extraction of plant material with acetic acid) char­
acteristic of the different treatments indicates that maleic

4

66

hydrazide to some extent influenced the soluble nitrogen
content of freshly harvested petioles of celery plants
approaching maturity.

The use of maleic hydrazide did not

cause a significant difference in soluble nitrogen content
in celery plants with the samples taken in June or July at
the low (10 ppm) nitrate level.

Chemical analyses of the

samples taken in August showed, however, that the controls
had a significantly higher soluble nitrogen content at the
low (10 ppm) nitrate level.

In striking contrast, at the

medium (20 ppm) nitrate level, the greatest differences
(increases) in soluble nitrogen content in the petioles
resulting from the maleic hydrazide treatments occurred
during the months of July and June.
Again, however, with the highest soil nitrate level

(75 ppm), a significant difference (decrease) in soluble
nitrogen content of the petioles occurred only during the
month of June (Table XVIII).
The Effect of Preharvest Sprays of Maleic Hydrazide on
the Sugar and Nitrogen Content of Two Varieties of Celery
as Influenced by Time in the Field After Spray
Applications and Length of the Storage Period (1951)
Methods and procedure.

Two commercially acceptable

varieties of celery, Cornell 19 (a golden type) and Utah 15
(a green type from Ferry-Morse, Detroit, Michigan) were
used in the first storage tests.

The experiment was designed

to determine the effects of preharvest foliar sprays of
maleic hydrazide on the percentage composition of total,
reducing, and non-reducing sugars, and total and nitrate

TABLE XVIII
THE EFFECTS OF VARIOUS .CONCENTRATIONS OF MALEIC HYDRAZIDE AND SOIL NITRATE LEVELS
ON THE ACETIC ACID SOLUBLE NITROGEN OF PETIOLES OF CORNELL 19 CELERY AT
VARIOUS TIMES DURING THE GROWING SEASON (1951)
Parts per million of soluble nitrogen in the petioles
Maleic
hydrazide
(ppm)

10

20

Sampled August 3
NO 3 levels

Sampled July 10
NO 3 levels

Sampled June 15
NO 3 levels
75

10

20

75

10

20

75.

0

759

1287

1561

1013

1261

1565

1300

1275

1717

25

692

1626

1375

797

llj.76

1750

1012

1325

1575

50

727

1725

1700

571

1506

1568

1012

1365

1787

100

787

1537

1U26

725

12 ij.6

1575

1051

1312

2002

250

551

753

1226

762

1119

1775

1085

1275

1835

703*20

1385*60

lij.57.60

773 *60

1321,60

l 61j.6,60

1092 .00

1310 .ij.0

1783.20

Means

Least differences
necessary for
significance
5% level 528

1% level

876

lak
687

27ij.

596

365

ij.00

117

293

639

990

606

665

18 ?

i+87

1060

68
nitrogen content of celery plants held under a number of
different storage conditions, and harvested at a time when
the crop had reached acceptable market maturity*
The design consisted of twelve 30-foot rows with
sixty plants each for each of the two celery varieties*
The two varieties of celery plants were sprayed September
19 with three concentrations of maleic hydrazide (500,
1000, and 2500 ppm)*

Comparable non-treated plots (rows)

served as control comparisons.
cated three times*

Each treatment was repli­

One-third of the celery from each plot

(20 rows) was harvested September 21 and placed in storage
until November 17 at 33 + 2° P*

A second third of the

celery was harvested on September 29, from which samples
were prepared without a period of storage*

For samples,

the entire aerial portion of three celery plants was
selected at random from each replication and treatment*
The remaining third was harvested on October 3» and placed
at the same storage temperature until November 17 as the
first lot of celery harvested September 21*

High humidity

(approximately 95 par cent relative humidity) was maintained
in the storage by periodically spraying water over the
celery*

At the completion of each storage period, the

samples were prepared by drying at 60° C and ground in a
large Wiley mill so as to pass through a 60-mesh screen*
For total, reducing and non-reducing sugar analyses,
five-gram single samples of ground material were taken from
each of the three replications and various treatments*

g

69

Chemical analyses were conducted according to procedures
outlined in "Methods of Analysis - Association of Official
Agricultural Chemists" (31)*
One-gram single samples from each of the three repli­
cations and various treatments were taken for total nitrogen
analyses#

The preparation of samples was identical to that

described above for sugar analyses#

Gunnings Method Modi­

fied to include nitrate nitrogen was used for total nitrogen
determinations (31)*
For nitrate nitrogen determinations, 0*5-gram single
samples of the plant material prepared as described above
for sugar and total nitrogen determinations was used#
Chemical analysis was according to "Jones Modification of
the Robertson Method" (31)•
Results#

The values obtained for the sugar deter­

minations are listed in Table XIX, and they suggest that
different preharvest sprays of maleic hydrazide influenced
the sugar content of celery at harvest time and during
storage#

Statistical analysis of the data showed that

maleic hydrazide treatments caused a significant increase
in per cent sugar content in stored celery as compared
with the controls (Table XIX)#

The two varieties of celery

used for this storage test also showed a significant
difference in sugar content when harvested 11 days after
treatment#

There was a significant interaction between

variety and treatment (Table XX)#

The celery plants which

remained in the field 15 days and in storage

days after

THE INFLUENCE OF PREHARVEST SPRAYS OF MALEIC HYDRAZIDE AND STORAGE AFTER TREATMENT ON
THE PER CENT SUGARS (TOTAL, REDUCING, AND NON-REDUCING) IK CORNELL 19 AND UTAH 15
VARIETIES OF CELERY (1951)

Variety

Cornell 19

Utah 15

Maleic
hydrazide
(ppm )

Method of handling
Field - 11 days*
Storage - none
Per cent sugars
Total
R
NR

after treatment with maleic hydrazide
Field - 15 days
Field - 2 days
Storage -1+5 days
Storage - 58 days
Per cent sugars
Per cent sugars
Total
R
NR
Total
R
NR

3.00

1.50

1.55

5 .5 2

2.00

3.52

8.02

1+.30

3.71

500

6.72

1+.914

1.78

8 .1 3

2.69

5.23

6.6l

2.22

1+.35

1000

5.26

3.01+

2.21

7 .2 8

1.89

5.39

1+.S9

1.21

3.67

2500

6.00

3.79

2.21

6 .91+

2.i|.8

1+.1+5

7.73

3.38

1+.35

Means

5.21+

3.32

1.93

5.11+

2.26

1+.65

6 .8 1

1+.65

1+.02

control

6.1+0

3.68

2.71

I+.38

1.55

2.83

5.02

2.1+5

2.60

M 8

2.53

2.36

5.90

2.08

3 .81

8.27

5.01

2.26

1000

7.16

1+.17

2.99

6.98

3.02

3.96

8.20

1+.73

3.1+6

2500

5.31+

2,60

2.71+

1+.92

1.19

3.39

5.82

2.67

3.15

Means

5.95

3.21+

2.70

5.51+

1 .9 6

3.1+9

6.82

3.71

2.86

1.1+6

1.26

0.61

0.67

0.68

0.52

1.13

0.61

1.11

2.01+

1.77

0.85

0.95

0.96

0.73

1.58

0.85

1.55

control

500

*

Least differences
necessary for significance
$% level

1% level

.... jj - j u :
^indicates days remained in field after application or spray material

TABLE XX
ANALYSIS OP VARIANCE TABLE ON PER CENT TOTAL SUGARS IN CORNELL 19 AND UTAH 1$
VARIETIES- OF CELERY AS INFLUENCED BY DIFFERENT PERIODS.OF STORAGE AND
VARIOUS PREHARVEST SPRAYS OF MALEIC HYDRAZIDE
(1951)

Method of handling after treatment with maleic hydrazide
S o u rce o f
v a r ia n c e

D e gre es
of
fre e d o m

F i e l d - 11 d a y s a
S to ra g e - none
T o ta l
Mean
sum o f
s q u a re s
s q u a re s

T o ta l

23

1+0.10

R e p lic a t io n

2

0.81

o.l+o

v a r ie ty

1

1 1 .2 6

1 1 .2 6

E r r o r (a).

2

0 ,6 5

0,32

T re a tm e n t

3

1 9 .1 0

6 .3 2

T re a tm e n t x
V a r ie t y

3

3 .2 7

1 .0 9

12

5 .0 1

0,1+2

E r r o r (b )

F i e l d - 15 days
F i e l d - 2 days
S to ra g e - 1+5 da ys
S to ra g e - 58 days
........... .................
.....................
• ■ ■T o ta l
Mean
T o ta l
Mean
siim o f
s q u a re s
sxim
o
f
s
q
u a re s
F
F
s q u a re s
s q u a re s

F

i+L+,20

1+5.70
0 ,5 7

0 .2 8

3.60

3 ,6 0

1 .6 3

0,81

1 5 .0 0 * *

7 .6 0

2 .S 3

2 .5 0 *

21+.10

8 .0 3

8 .1 6

0 ,6 8

1 .2 0 NS
3 5 .1 0 *

,s“* H ig h ly s i g n i f i c a n t (1% l e v e l )
S i g n i f i c a n t (5% l e v e l )
NS N o t s i g n i f i c a n t
a I n d ic a t e s days re m a in e d i n f i e l d

0,90

0.1+5

0 .0 0 1

0 .0 0 1

0 ,2 0

0 .1 0

3 .7 2 *

3 .5 0

1 .1 6

8 , 30* *

1 1 .8 0 * *

3 7 .9 0

1 2 .6 3

9 0 .2 0 * *

1 .7 0

0.11+

—

1+.1+1+ NS

a f t e r a p p l i c a t i o n o f s p ra y m a t e r ia l
s

1+.5 'NS
—

maleic hydrazide applications, showed the greatest differ­
ences in the percentages of the sugar fractions among the
maleic hydrazide treatments, and in contrast, those which
remained in the field 11 days after maleic hydrazide appli­
cations and had no storage period showed the least differ­
ences in sugar composition resulting from maleic hydrazide
treatments*
Table XXI shows the influence of preharvest sprays of
maleic hydrazide on the per cent Cf total nitrogen and
nitrate nitrogen in stored celery.

A statistical analysis

of the data shows that preharvest foliar sprays of maleic
hydrazide had little influence on the per cent of total
nitrogen and nitrate nitrogen in stored celery with the
exception of nitrate nitrogen in Cornell 19 which remained
in the field 1$ days and in storage 2*5 days after maleic
hydrazide treatments.
The Effect of Preharvest Sprays of Maleic Hydrazide on
the Sugar Composition of Two Varieties of Celery Plants
as Influenced by Various Times of Storage (19^2)
Methods and procedure.

Two varieties of celery,

Cornell 19* a golden type, and Utah 52-70, a green type
selected from Utah 1$, were used for the second storage
test.

The experiment was designed in part to repeat certain

phases of the first test and to determine the effects of
maleic hydrazide on the sugar content of celery stored
for different periods of time.

The field design consisted

of twelve ten-foot rows (plots) containing twenty plants
each for each of the two celery varieties.

THE INFLUENCE OF PREHARVEST SPRAYS OF MALEIC HYDRAZIDE AND STORAGE ON THE PER CENT
NITROGEN (TOTAL AND NITRATE) IN CORNELL 19 AND UTAH 15 VARIETIES OF CELERY (1951)

Variety

Cornell 19

Utah 15

Maleic
hydrazide
(ppm)

Field - 11 days*
Storage - none
Per cent nitrogen
Total
Nitrate

Field - l£ days
Storage
I4$ days .
Per cent nitrogen
Total
Nitrate

Field - 2 days
Storage - £8 days
Per cent nitrogen
Total
Nitrate

2*71

O.II4.

2.65

0.07

2.52

0,06

500

2.51

0.18

2.88

0,214.

2.68

0.17

1000

2.36

0 .014-

2.71

0.06

2.85

0 .l£

2500

2.29

0,10

2.61

0.16

2.58

0,11

Means

2 .I4.6

0.11

2.71

0.13

2.65

0.12

control

2.14-9

0.20

2.70

0 .2 £

2.68

0.16

£00

2.£2

0.29

2 .6I4.

0.19

2.61

0.10

1000

2 .2?

0 .l£

2.63

0 .2i|.

2.32

0.03

2500

2.3U-

0,11

2.55

0.22

2.39

0.13

Means

2 .14.0

0.18

2.63

0.22

2.50

0.10

0.39

0.19

0.26

0.09

0,13

0.21

0.55

0.26

0.36

0.13

0.19

0.30

control

Least differences
necessary for significance
5$ level

1% level

Method of handling after treatment with maleic hydrazide

^Indicates days remained in field after application of spray material

TABLE XXII
ANALYSIS OP VARIANCE TABLE ON PER CENT TOTAL NITROGEN IN CORNELL 19 AND UTAH 15
VARIETIES OP CELERY AS INFLUENCED BY DIFFERENT PERIODS OF STORAGE AND
VARIOUS PREHARVEST SPRAYS OF MALEIC HYDRAZIDE
(1951)
M eth od o f h a n d lin g a f t e r t r e a tm e n t w i t h m a le ic h y d r a z id e
S o u rce o f
v a r ia n c e

T o ta l

D egrees
of
fre e d o m

T o ta l
Mean
sum o f s q u a re s
s q u a re s

F i e l d - 2 .days
S to ra g e - 59 days

F i e l d - 15 days
S to ra g e days

F i e l d - 11 d a y s 0S to ra g e - none

Mean
T o ta l
sum o f
s q u a re s
sq u a re s

F

F

1 .3 6

T o ta l
Mean
s q u a re s
sum o f
s q u a re s

F

1 .2 0

23

0.32;

R e p lic a t io n

2

0 ,1 1

0 .0 5 3

11.00 NS 0 .1 2

0 ,0 6 0

a* mm

0 .2 3

0 .1 1 5

23.0 0<»

V a r ie t y

1

0 .0 2

0 .0 2 0

Ip. 00 NS 0 .0 5

0.050

«n o»

0 .1 2

0 .1 2 0

’
24.0 ■ic

E r r o r (a )

2

0 .0 1

0 .0 0 5

0 .1 5

0 .0 7 5

0 .0 1

0 .0 0 5

T re a tm e n t

3

0.02;

0 .0 1 3

2 .1 0 NS O . lh

0 .0 1 3

2 .6 0 NS

0 .2 0

0 .0 6 0

2.2; NS

T re a tm e n t x
V a r ie t y

3

0 .0 9

0 .0 3 0

5 .0 0 b5*

0 ,2 6

0.086

1 .7 0 NS

0,3L|.

0 .1 1 3

i; . 5 -rr

12

0 .0 7

0 .0 0 6

0,61}.

0 .0 5 0

0 .3 0

0 .0 2 5

E r r o r (b )

S i g n i f i c a n t (5 $ l e v e l )
NS N o t s i g n i f i c a n t
a I n d ic a t e s days re m a in e d i n

\s>

f ie ld

a f t e r a p p l i c a t i o n o f s p ra y m a t e r ia l

75
On July 23, 1952, three concentrations of maleic
hydrazide

00, 1000, and 2^00 ppm) were applied to the

two varieties of celery plants with non-treated plots
serving as controls.
each treatment.

There were three replications of

The plants were permitted to remain in

the field until July 31, at which time they were harvested,
trimmed, put in crates, and placed in a storage room held
at 33 + 2° P,

The celery had reached market maturity at

the time of harvest*
Water was sprayed over the stored celery periodically
to maintain a high relative humidity (95-98 per cent).
One-third of the celery (the entire aerial portion of three
plants per replication and treatment) was removed on August
15, sampled, dried, and ground after a l£-day storage period.
Sampling, drying, and grinding were similar to that described
under the first storage test for 1951*

A second third of

the celery was taken out of storage on August 29, after a
29-day storage period, for sampling, drying, and grinding*
On September 12, after a 43-day storage period, the remain­
ing third of the celery was removed from storage and
representative samples similarly prepared in the usual
manner for chemical analyses.
The methods and procedure used for sugar determination
were identical to those described under methods and pro­
cedure for sugar determinations in the 1951 storage test*
Total nitrogen and nitrate nitrogen determinations were
not made.

76
Results*

Generally the per cent of sugars was lower

and less significant statistically from this storage test
than from the first storage test*

However, the data in

Table XXIII show that after I4.3 days of storage significant
increases in sugar content resulted from treatment of
Utah 52-70 with maleic hydrazide; however, a decrease was
generally noted with Cornell 19*

i

THE INFLUENCE OF PREHARVEST SPRAYS OF MALEIC HYDRAZIDE AND STORAGE ON THE PER CENT
SUGARS (TOTAL, REDUCING, AND NON-REDUCING) IN CORNELL 19 AND UTAH £2-70
VARIETIES OF CELERY (19£2)
Method of handling after treatment with maleic hydrazide
Variety

Cornell 19

Utah £2-70

Maleic
hydrazide
(ppm)

Storage - 29 days
Per cent sugars
Total
R
NR

Storage - k3 days
Per cent sugars
Total
R
NR

l.*|2

1.16

0.29

2.7£

i.££

1.20

*1-89

3.27

1,61

£00

2,10

l.£6

0.£l*.

2.L|2

1*£8

0.83

2.99

1.92

0.08

1000

1.7£

1.1*1

0.3*1-

2.69

1.62

1.07

2.8£

l.£9

1.26

2£00

l.*s-9

1.23

0.26

2.68

1,66

1.02

3.69

2.03

1.67

Means

1.69

1.3k

0.3£

2.63

1.60

1.03

3.60

2.20

i.ko

control

1.66

1.18

O.i+7

3.£*1-

2.02

l.£l

2.23

0.90

1.32

£00

1.67

l.ill

0.26

*1-,*1.6

2.77

1.67

3.89

1.99

1.90

1000

1.96

1.28

0.68

2.81

1.37

1.11

3.kk

1.7£

1.69

2£00

2.ijJ

1.79

0.67

3.9*1-

2.16

1.77

3.k0

1.31

2.08

Means

1.9*1-

l.ill

0.£2

3.68

2.08

l.£l

3.2k

l.il-8

1.7k

0.9£

0.63

O.U

1.70

l.k3

0.£*i-

1.2*1.

1.06

0.£3

1.3*1-

0.88

0,61

2.l|.0

2.01

0.76

1.7*1-

l.il-9

0.7*1-

control

Least differences
necessary for significance
5% level

1% level

Storage - l£ days
per cent sugars
Total
R
NR

TABLE XXIV
ANALYSIS OP VARIANCE TABLE ON PER CENT TOTAL SUGARS IN CORNELL 19 AND UTAH 52-70
VARIETIES OP CELERY AS INFLUENCED BY DIFFERENT PERIODS OF STORAGE AND
VARIOUS PREHARVEST SPRAYS OF MALEIC HYDRAZIDE
(1952)
Method of handling after treatment with maleic hydrazide
Source of
variance

Degrees
Storage - 15 days
of
Total
Mean
freedom sum of squares
F
squares

Storage - 29 days
Total
Mean
sum of squares
p
squares

23

6.31

Replication

2

0.13

0.065

1.30 NS

3.91

1.95

97.S0 *

0.10

0 .0 5 0

wmwm

Variety

1

0.36

0.360

7.20 NS

6.70

6.70

335.00*«

0.80

0.800

«*«•

Error (a)

2

0.10

0.050

O.Olj.

0.02

14.614

2.320

Treatment

3

0.614,

0.210

1.60

0 .5 3

0.60

0.200

mm*

Treatment x
Variety

3

i.5i

0.520

2.814

0 .9 5

1.00 NS 11.70

3.900

7.95**

12

3.57

0.290

11.37

0 .9 5

5.91|

0.14-90

Total

$rror (b)

26 .14.6

Storage - I4.3 days
Total
Mean
sum of squares F
squares

—
1.79 NS

Highly significant (1% level)
# Significant (5$ level)
NS Not significant

23.78

V*

GENERAL DISCUSSION

Some Effects of Maleic Hydrazide on the Vegetative
Growth of Celery Plants
The effects of foliage applications of maleic hydra­
zide on the vegetative growth of celery (variety Cornell
1 9) were dependent largely upon age of the plants when
treated, concentrations of maleic hydrazide applied, pre­
vious temperature exposures, and the nitrate nitrogen
status of the soil in which the plants were growing*
Results from these studies showed that greater injury
occurred from comparable concentrations of maleic hydra­
zide applied on plants which did not receive low night
temperature (lj.0 + 5° F) exposures before transplanting to
the field than on those which received a low temperature
treatment prior to field transplanting*

Celery plants

which received low temperature treatments prior to trans­
planting undoubtedly were in a physiological condition;:
which permitted greater tolerance to higher concentrations
of maleic hydrazide without observable injury*
High soil nitrate levels induced rapid growth of
celery plants.

Such plants were more susceptible to maleic

hydrazide injury than those which grew less rapidly at the
lower levels of nitrate*

Maleic hydrazide inhibited vege­

tative growth more wherever conditions for growth were more

favorable (15, 28, 29, 33)*
Little Injury was observed on any of the plants,
regardless of age or previous handling, which received
concentrations of maleic hydrazide below 100 ppm (6 ).

In

the ease of older celery plants, much higher concentrations
of maleic hydrazide were applied with little apparent
injury (8 ),

Thus, old maturing plants are capable of

tolerating high concentrations of maleic hydrazide with
less inhibition of vegetative growth than young growing
plants (6, 8 , I4.8 ),

Schoene and Hoffman (I4.8 ), Compton (6 ),

and Crafts, e_t al (8 ) also observed that maleic hydrazide
inhibited vegetative plant growth temporarily if physio­
logically tolerable concentrations were applied.

Obser­

vations made during the course of these studies indicated
that temporary inhibition of vegetative growth in celery
plants was dependent upon whether or not physiologically
tolerable concentrations of maleic hydrazide were applied
(79)*
The highest physiologically tolerable concentration
of maleic hydrazide that could be applied to celery plants
would certainly depend upon a number of factors.

Reference

to Figure 2 shows that 250 ppm of maleic hydrazide seriously
injured celery plants which did not receive a low temper­
ature treatment before transplanting to the field, and
grown at a high soil nitrate (75 ppm) level*

These plants

were nine weeks old at the time maleic hydrazide was applied*
Other observations revealed that 300 ppm of maleic hydrazide
completely killed 13-week old celery plants.

In striking

contrast, 1000 ppra of maleic hydrazide did not kill 20week old celery plants (Figure 9)*
When maleic hydrazide concentrations were high enough
to inhibit terminal vegetative growth, some stimulation of
lateral bud growth was observed (79)•

In many instances

where terminal vegetative growth was inhibited, no later
terminal growth took place.

This would 3eem to indicate

that further division of the apical cells was inhibited
permanently, and that apical dominance was destroyed#
Enlargement of the celery plant stems was noticed in most
oases where apical dominance was destroyed#

This was true

especially under greenhouse conditions when the plants
were grown at 70° F night temperatures and at 100 ppm of
soil nitrate#
Studies by Leopold and Klein (33) and Bonner and
Bandurski (1) showed that auxins are necessary for apical
dominance in plant growth#

Work with plant growth regulators

such as triiodibenzoic acid, coumarin, 2,^-chloranisole,
and trans-cinnamic acid has shown that these substances
possess capacities to lessen or destroy apical dominance
(33)#

Therefore, these plant growth regulators are classed

as anti-auxins because of their inhibitory action on apical
growth in plants#
Maleic hydrazide destroys apical dominance in celery
plants, depending upon concentrations applied and age of
the plant; thus, it would seem that this compound acts as
an anti-auxin with celery plants (33)*

The anti-auxin

82
action of maleic hydrazide seams to be dependent upon the
natural auxin level already present within celery plants*
If the auxin level is high and low concentrations of maleic
hydrazide are applied, apical dominance is not completely
destroyed, but is decreased according to the amount of
maleic hydrazide present*

The temporary inhibition of

apical growth in celery plants if certain concentrations
of maleic hydrazide are applied suggests that natural
plant auxins have overcome the inhibitory effect of this
anti-auxin*
The Effects of Maleic Hydrazide on Flowering
in Celery Plants
It has been reported in the literature that maleic
hydrazide exerts variable influences on the reproductive
processes in various plants*

Naylor (i|3), using 0*1 per

cent (1000 ppm), 0*2 per cent (2000 ppm), 0*ij. per cent
(lj.000 ppm), and 0*8 per cent (8000 ppm) of maleic hydrazide
on Xanthium plants, noted that 0*1 per cent colutions of
maleic hydrazide reduced flowering by 50 per cent (32, 3^1-) •
White and Kennard (67) used maleic hydrazide at 1000, 1^00,
2000, and 3000 ppm on apples, strawberries, and black rasp­
berries and noted responses from no effect on flower in­
hibition in apples to a delay of blossoming from 2ij. to 38
days in black raspberries*

Thus, variable reproductive

responses of different plants to treatment with maleic
hydrazide have been fairly well established*

83
Even though the investigations herein reported did
not clearly indicate that maleic hydrazide will prevent
floral initiation in Cornell 19 celery plants, there were
clear indications, however,

that high concentrations of this

compound applied to older celery plants w o u l d inhibit seedstalk elongation which may or may not be an independent
process (Figure 7)*

Clear distinctions have not been

reported In the literature b y investigators between inhi­
b ition of flower priraordia formation and inhibition of
anthesis as influenced by maleic hydrazide concentrations.
Results of these studies w i t h celery plants showed that
the reduced number of flowers which formed at high con­
centrations of maleic hydrazide were due primarily to
inhibition of growth and development of seedstalks sub­
sequent to floral initiation.

Maleic hydrazide applied

at $0, 75>» and 100 p p m to nine-week old celery plants
significantly increased the per cent and earliness of
seeastalk initiation (Figures 3 and $)•

The extent of

increase In earliness and per cent of seedstalk initiation
was determined by the age of the plants at the time of
maleic hydrazide application, nitrate levels maintained
In the soil, and previous temperature exposures.

Thus

there were Indications that maleic hydrazide can hasten
flower initiation in celery, and celery normally a biennial,
can be induced by chemical treatment to react as an annual.
These findings would seem to indicate that maleic
hydrazide has greater possibilities as a reproductive growth

promoting substance, in the case of Cornell 19 celery,
than as a substance for the Inhibition of floral initiation*
Such observations would seem to assume vast economic
Importance from the standpoint of the plant breeder, seed
grower, and the control of flowering and fruiting responses
of horticultural crops, in general,
Lang (30) has pointed out that sugar has substituted
for light inductive periods in both long-day and short-day
plants such as Spinacia, Hyoscyamua, Xanthium, and Chenopodium in Inducing floral initiation.

Whether or not

sugar promotes the production of substances which are
necessary for flower initiation is not definitely known
($3* 54* 56),

The hastening of floral Initiation in Cornell

19 celery by maleic hydrazide treatments would seem to have
a relation to the function of sugar in inducing floral
initiation in the genera mentioned above#

The capacity

which maleic hydrazide possesses to induce floral init­
iation in long-day plants as Cornell 19 celery might
result from two changes which occur within the plant,
namely,

(a) lowering of the natural auxin level, and/or

(b) an increase in the carbohydrate nitrogen ratio.
General observations Indicated that those plants which
were induced to flower from early maleic hydrazide treat­
ments produced larger inflorescences than the controls.
This increase in size of the seedstalks and inflorescences
from early maleic hydrazide treatments, suggests that after
maleic hydrazide had induced floral Initiation, natural

auxin accumulation counteracted further effects of maleic
hydrazide*

Therefore accumulated auxins could be used for

seedstalk elongation and development*
Though low temperature treatments advanced the date
of floral initiation, those plants which did not receive a
low temperature treatment but were sprayed early with
maleic hydrazide, later produced inflorescences just as
large as the cold-induced plants (11, 50, 57, 58)•

Whether

maleic hydrazide induces internal responses in celery plants
which are similar to those brought about by low temperature
exposure is not known but it is highly suggestive (5l)*
W h e n young celery plants received both maleic hydrazide
and low temperature treatments floral initiation was greatly
favored*

Figure 8 shows inflorescences which resulted

from early applications of maleic hydrazide on plants which
did not receive a low temperature treatment for seedstalk
initiation*
There appeared to be a relationship between the appear­
ance of seedstalk initials and the growth and maturity
of inflorescences*

Plants on which seedstalk initials were

first observed (July 2) were those on which full bloom
(August 10) first occurred and ripened seed (October 5)
were first evident*
The unique plant growth regulatory effects which maleic
hydrazide possesses to induce seedstalk initiation at low
concentrations when applied early in the development of the
celery plant, and to prevent seedstalk elongation at high

86
concentrations later in the development of the same plant,
m a y be partly explained from its anti-auxin characteristics*
L o w auxin levels are required for seedstalk initiation and
high auxin levels are required for subsequent growth and
development (30).

It has b e e n demonstrated by Leopold and

K l e i n (33) that maleic hydrazide functions as an anti-auxin
and results obtained from maleic hydrazide applications
on celery plants show that this chemical perhaps lowered
the auxin level in young celery plants to the extent that
floral initiation was favored.

B y the same token, the

anti-auxin effect of maleic hydrazide likely enabled it to
inhibit seedstalk elongation when applied at high concen­
trations during the later stages of flower formation, but
prior to seedstalk development when the auxin economy of
the meristems was much different.

High auxin levels are

required for the elongation and development of seedstalks
(1, 30, 33).
The Influence of Maleic Hydrazide on the Quality
of Stored Celery
Investigations as to the possibility of the use of
preharvest foliage sprays of maleic hydrazide to prevent
storage losses in celery seemed feasible from reports by
W i t t w e r and Paterson (lij., 71) that this chemical reduced
storage losses and influenced favorably the carbohydrate
status in sugar beets and potatoes; and recent work by
Smock (49) on the reduction of storage losses with apples*

8?
The reduction in storage losses as evidenced by sugar per­
centages in celery plants by the use of maleic hydrazide
was investigated.

Results of these studies indicated that

maleic hydrazide under some conditions may reduce sugar
losses in celery, although significant variety interactions
were noticed.

The degree to which storage losses were

reduced depended to some extent upon the length of time the
plants remained in the field after maleic hydrazide was
applied.

A comparison of Tables XIX and XXIIT shows that

maleic hydrazide did not greatly influrace sugar percentages
in celery that was harvested in July of 195>2.

Table XIX

shows that preharvest foliage sprays of maleic hydrazide
had a greater influence on sugar percentages of celery
plants harvested in September of 1951*
Currier, Day, and Crafts (10), working with cotton and
barley, and Naylor (i|l), with c o m , observed that maleic
hydrazide at 0.2 per cent (2000 ppm) and 0 ml± per cent (i|.000
ppm) favored sugar accumulation.

The accumulation of sugars

following maleic hydrazide treatments may result from
collapse of the phloem elements (10).

The effect of maleic

hydrazide on sugar accumulation in stored celery might be
explained further from observations made by White (66) and
Isenberg (27) which showed that maleic hydrazide Inhibits
the activity of various dehydrogenases essential in certain
phases of plant respiration Involving the utilization of
sugar.

Generally a large proportion of the storage losses

In many perishables may be considered those which Involve
sugars.

VI.

SUMMARY

Maleic hydrazide applied as a foliage spray at con«=
centrations of 50, 75* and 100 ppm to Cornell 19 celery
plants which were 13 to 16 weeks old (6 -8 inches in height)
significantly hastened the formation of seedstalk Initials
and increased both the percentage of plants forming seed­
stalks and the average heights of seedstalks, while spray
concentrations of maleic hydrazide of 500 to 1000 ppm
applied to plants 20 to 22 weeks old (1 2-16 inches in
height) inhibited seedstalk elongation.

Maleic hydrazide

induced seedstalk development in celery plants which had
not b e e n exposed to a low night temperature (ij.0 + 5° F)
treatment before transplanting to the field.
Exposure to low night temperature markedly increased
the ability of young celery plants to tolerate high con­
centrations of maleic hydrazide, while young celery plants
grown at high soil nitrate levels (75 " 100 ppm) under
greenhouse and field conditions were less tolerant.

In

the field, an increase in height of seedstalks which formed
was noted in plants grown at high (75 ~ 100 ppm) levels of
soil nitrates.
I n the greenhouse with Cornell 19 celery plants grown
at I4.0 , 60, and 70° F night temperatures,

the most pronounced

positive influence on seedstalk initiation and subsequent

89
growth and development of seedstalks occurred at J4.O0 F*
This was true irrespective of maleic hydrazide treatments*
A low soil nitrate level (10 ppm) favored seedstalk growth
and development regardless of the temperature at which the
plants were growing*
Storage tests with two varieties (Cornell 19 and Utah

15 ) of celery were conducted wherein foliage sprays of
maleic hydrazide (500 , 1000 , and 2500 ppm) were applied
prior to harvest*

The celery which was harvested and

subsequently stored at 33 + 2 ° F for various periods of
time was analyzed for total, reducing, and non-reducing
sugars; and for total and nitrate nitrogen*

No significant

alterations in total or nitrate nitrogen were observed*
However, significant Increases and decreases in sugars
were characteristic of some of the maleic hydrazide treat­
ments, but not others, and several inconsistencies were
noted in the results of the two storage tests*
Tissue analyses of fresh celery petioles harvested
from plants of various ages and grown at 10, 20, and 75
ppm of soil nitrate, revealed that foliage sprays of maleic
hydrazide of 100 to 250 ppm decreased the soluble nitrogen
content*

VII.
1.

LITERATURE CITED

Bonner, J., and Bandurski, R. S* Studies of the
physiology, pharmacology, and biochemistry of the
auxins. Annual Review of Plant Physiology, 3:59-

,

.

86 1952
2*

Carolus, R. L* Truck crop investigations* The use
of rapid chemical plant nutrient test in fertilizer
deficiency diagnoses and vegetable crop research*
Va* Truck Exp* Sta. Bui*, 98* 1938*

3.

Cholodny, N. G. The internal factors of flowering*
Herbage Rev*, 7:223-2lj.7* 1939*

if.*

Clark, B* E*, and Wittwer, S* H* Effect of certain
growth regulators on seed stalk development in lettuce
and celery* Plant Physiol*, 2l{.:555-576* 19i+9*

5.

Clark, H* C*, and Kerns, K. R* Control of flowering
with phytohoraones* Science, 95:536-537. 19i|-2*

6*

Compton, Winifred* The effects of maleic hydrazide on
growth and cell division in Pi sum sativum*
Torrey Bot*
Club Bui*, 79:205-211* 1952.
'

7.

Cooper, W* C* Effect of growth substances on flowering
of the pineapple under Florida conditions* Proc.
Amer* Soc. Hort* Sci*, i|l:93-98* 19ip!.

8.

Crafts* A* S*, Currier, H* B*, and Day, B* E* Response
of several crop plants and weeds to maleic hydrazide*
Hilgardia, 20:57-80. 1950.

9.

Currier, H* B*, and Crafts, A. S* Maleic hydrazide,
a selective herbicide. Science, 111:152-153* 1950*

10*

Currier, H* B., Day, B* E., and Crafts, A* S. Some
effects of maleic hydrazide on plants* Bot* Gaz.,

112:272-280. 1951.

11*

Curtis, 0. F., and Chang, H* I*The relative effect­
iveness of the temperature of the crown as compared
to that of the rest of the plant upon the flowering
of celery* Abstract* Amer. Jour* Bot., 17:10k710i|8. 1930*

12.

Darlington, C. D., and McLeish, J. Action of maleic
hydrazide on the cell. Nature, l67:lj.07-i].08. 1951.

91
13.

D o s ta l, Van. R», and H osek, M* U ber den E in f lu s s von
H e te ro a u x in a u f d ie m orphogenase b e i G ir c e ae (das
S achssche phanom en). F lo r a N . F . , 3 1 1 9 3 7 .

I ll#

E r ic k s o n , L . C ., and p r i c e , G.
h y d ra z id e on su g a r b e e t p la n t s .
3 7 :6 5 7 -6 5 9 . 1950.

15.

F illm o r e , R. H .
The c o n t r o l o f p la n t de velop m en t w it h
m a le ic h y d r a z id e . A r n o ld ia , 1 0 :3 3 -3 9 . 1950.

16.

G a ls to n , A r t h u r W. The e f f e c t o f 2 , 3 , 5 - t r iio d o b e n z o ic
a c id on th e g ro w th and f lo w e r in g o f soyb ea ns. Amer.
J o u r . B o t . , 3 if : 3 5 6 -3 6 0 . 1914-7.

17.

G reen, M a rio n , and F u l l e r , H. J . I n d o le - 3 - a c e t ic a c id
and f lo w e r in g .
S c ie n c e , 1 0 8 :Ij.l5 -Ip -6 . 191+.&.

18#

G re u la c h , V. A .
The e f f e c t o f m a le ic h y d ra z id e on
th e to m a to p la n t s i n r e l a t i o n to t h e i r age a t th e tim e
o f t r e a tm e n t ,
p la n t P h y s io lo g y , 2 6 :8 i|8 -8 5 2 * 1951*

19.

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