THE INFLUENCE OF PREPIANTING
DIPS AND POSTPLQNTING TEMPERATURES
0N ROOT GROWTH AND QEVELOPMENT -
0F TULIPS, HYACIN'ITHS, AND DAFFODILS

Thesis for the Degree of M. S.

MICHIGAN STATE UNIVERSITY —

E‘IANCY THOMPSON JENNINGS
1978

 

  
  
 

    
 

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ABSTRACT

THE INFLUENCE OF PREPLANTING DIPS AND POSTPLANTING
TEMPERATURES ON ROOT GROWTH AND DEVELOPMENT
OF TULIPS, HYACINTHS, AND DAFFODILS

BY

Nancy Thompson Jennings

The rooting of 'Paul Richter' tulips, 'Explorer'
daffodils, and 'Pink Pearl' hyacinths was conducted in dark,
temperature controlled growth chambers. Tulip and daffodil
bulbs were rooted at 5, 9, 13, 17, and 21°C whereas
hyacinths were rooted at 9, 13, 17, 21, 25, 29, and 33°C.
In 1973, each bulb species was sampled for root develOpment
at weekly intervals for five weeks. This was repeated in
1974 for tulips and daffodils, but the hyacinths were
sampled at five day intervals for 25 days. Preplanting
treatments of a 30 minute benomyl-ethazol dip in 1973 and
1974 and a 30 minute water dip in 1974 were conducted in
conjunction with the time-temperature study. The para-
meters studied were number of bulbs rooted per pot, fresh
root weight, and average root length.

It was determined that 17°C for three weeks and
17°C for three to four weeks were the Optimal temperatures

for root development of tulips and daffodils, respectively.

Nancy Thompson Jennings

For hyacinths, a range from 17 to 25°C for 10 to 14 days
was Optimal. Under the above conditions, the root length
was 70 mm or greater and the number of bulbs rooted per pot
was 100% for each Species. This growth is suitable for
carrying the bulbs through the cold treatment.

It was also established that 9 and 13°C were suffi-
cient for rooting tulips if four weeks were allowed for
development. Temperatures 5 and 21°C remained suboptimal
throughout the five week rooting period. Though yielding
100% rooted per pot, tulips at 5°C never obtained root
growth near the Optimal 70 mm. Bulbs at 21°C produced
greater than 70 mm of root growth but they did not all
root. There was also a problem with Fusarium at 21°C. The
daffodils rooted well at 9 and 13°C but four to five weeks
were needed instead of three weeks at 17°C. Three weeks
were sufficient at 9 and 13°C for 100% rooting of bulbs
per pot. Daffodils which rooted at 5°C did not produce
roots longer than the Optimal 70 mm during the five week
period. In most cases at 21°C, daffodil root development
was inhibited. Temperatures below 17°C and above 25°C were
also adequate for root develOpment of the hyacinth but
development took from a week to 15 days longer than the
optimal range of temperatures took. An increase in Eythium
and Fusarium was observed at temperatures above 25°C.

The benomyl-ethazol and water preplanting dips
were effective in stimulating root growth for the first

two weeks for the tulips. This was not Observed for

Nancy Thompson Jennings

hyacinths or daffodils. The benomyl-ethazol dip was also
significantly better than the non-dipped control and water
dip after five weeks of root grOwth for all bulb species.

It was Observed that this was due to disease protection.

THE INFLUENCE OF PREPLANTING DIPS AND POSTPLANTING
TEMPERATURES ON ROOT GROWTH AND DEVELOPMENT

OF TULIPS, HYACINTHS, AND DAFFODILS

BY

Nancy Thompson Jennings

A THESIS

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

MASTER OF SCIENCE

Department of Horticulture

1976

To my sister, Ruthie.

ii

ACKNOWLEDGMENTS

I wish to extand my sincere appreciation to my major
professor, Dr. August De Hertogh, for his guidance and
direction during this period of my graduate studies.
Appreciation is also extended to Drs. Ken Sink and Gary
HOOper for their guidance and critical inputs. The help
and assistance of Mr. Norman Blakely, Vladex Szlachetka,
and Jim Wolpert was invaluable. My warm thanks is given
to the Netherlands Flower—bulb Institute for their gracious
financial assistance.

Most of all, I want to take this opportunity to
thank my friend and spouse, Sam, for his understanding of my

needs to make science my profession.

iii

TABLE OF CONTENTS

LIST OF TABLES O O O O O C O O O 0

LIST

I.

II.

III.

IV.

OF FIGURES. . . . . . . . . .
LITERATURE REVIEW . . . . . . .

Introduction . . . . . . . .

Factors Influencing Root Initiation and

DevelOpment. . . . . . . .

Temperature. . . . .
The Fungicide 'Benomyl'.
Ethylene. . . . . .
Soil Compaction . . .
Bulb Size and Shape . .

Contractile Roots of Bulbous Species
INTRODUCTION. . . . . . . . .
METHODS AND MATERIALS. . . . . .

Tulip . . . . . . . . . .

Hyacinth
Daffodil

MSULTS O O O I O O O O O O
Tulip 'Paul Richter' . . . . .

Number of Bulbs Rooted per Pot .
Average Root Length (mm) . . .
Fresh Root Weight (g/bulb). . .

Hyacinth 'Pink Pearl' . . . . .
Number of Bulbs ROoted per Pot .

Average Root Length (mm) . . .
Fresh Root Weight (9/bu1b). .

iv

Page
vi

xi

(1) caucuses

11
13
14
14
15
16
16
16
26
26
26

32
32

Page

Daffodil 'Bxplorer'. . . . . . . . . 39

Number of Bulbs Rooted per Pot . . . . 39

Average Root Length (mm) . . . . . . 47

Fresh Root Weight (g/bulb). . . . . . 52

V. DISCUSSION 0 O O O O O O O O O O O 57
VII. LITERATURE CITED . . . . . . . . . . 71
APPENDIX 0 O O O O O O O O O O O O O O 75

Table

1.

10.

LIST OF TABLES

The influence of temperature and sampling
time treatments on number of 'Paul Richter'
tulips rooted per pot, 1973 . . . . . .

The influence of preplanting treatments and
sampling time on number of 'Paul Richter'
tulips rooted per pot, 1973 . . . . . .

The influence of temperature and sampling
time treatments on the number of 'Paul
Richter' tulips rooted per pot, 1974 . . .

The influence of temperature and sampling
time treatments on the growth of roots (mm/
bulb) for 'Paul Richter' tulip, 1973 . . .

The influence of preplanting treatments and
temperature on growth of roots (mm/bulb)
for 'Paul Richter' tulip, 1973 . . . . .

The influence of preplanting treatments and
sampling time on the growth Of roots (mm/
bulb) for 'Paul Richter' tulip, 1973 . . .

The influence of temperature and sampling time
treatments on the growth of roots (mm/bulb)
for 'Paul Richter' tulip, 1974 . . . . .

The influence of preplanting treatments and
temperature on the growth of roots (mm/
bulb) for 'Paul Richter' tulip, 1974 . . .

The influence of preplanting treatments and
sampling time on the growth of roots (mm/
bulb) for 'Paul Richter' tulip, 1974 . . .

The influence of temperature and sampling

time treatments on the growth Of roots (9/
bulb) for 'Paul Richter' tulip, 1973 . . .

vi

Page

17

19

20

21

22

22

23

24

25

27

Table

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

The influence of a preplanting treatments and
sampling time on root growth (g/bulb) for
'Paul Richter' tulip, 1973 . . . . . .

The influence of temperature and sampling
time treatments on root growth (g/bulb) for
'Paul Richter' tulip, 1974 . . . . . .

The influence of preplanting treatments and
temperature on root growth (g/bulb) for
'Paul Richter' tulip, 1974 . . . . . .

The influence of preplanting treatments and
temperature on the number of 'Pink Pearl'
hyacinth rooted per pot, 1973 . . . . .

The influence of temperature and sampling
time treatments on the root growth (mm/bulb)
for 'Pink Pearl' hyacinth, 1973 . . . .

The influence of preplanting treatments and
temperature on the root growth (mm/bulb) for
'Pink Pearl' hyacinth, 1973. . . . . .

The influence of preplanting treatments and
sampling time on root growth (mm/bulb) for
'Pink Pearl' hyacinth, 1973. . . . . .

The influence of temperature and sampling-
time treatments on root growth (mm/bulb)
for 'Pink Pearl' hyacinth, 1974 . . . .

The influence of preplanting treatments and
temperature on the growth of roots (mm/bulb)
for 'Pink Pearl' hyacinth, 1974 . . . .

The influence of preplanting treatments and
sampling time on the growth of roots (mm/
bulb) for 'Pink Pearl' hyacinth, 1974 . .

The influence of temperature and sampling time
treatments on root growth (g/bulb) for
'Pink Pearl' hyacinth, 1973. . . . . .

The influence of preplanting treatments and

sampling time on root growth (g/bulb) for
'Pink Pearl' hyacinth, 1973. . . . . .

vii

Page

28

29

30

31

33

34

35

36

37

38

40

41

Table Page

23. The influence of temperature and sampling
time treatments on root growth (g/bulb)
for 'Pink Pearl' hyacinth, 1974 . . . . 42

24. The influence Of preplanting treatments and
temperature on root growth (g/bulb) for
'Pink Pearl' hyacinth, 1974 . . . . . 43

25. The influence of temperature and sampling time
treatments on number of 'Explorer' daffodils
rooted per pot, 1973. . . . . . . . 44

26. The influence of preplanting treatments and
temperature on number of 'Explorer' daffodils
rooted per pot, 1973. . . . . . . . 45

27. The influence of temperature and sampling time
treatments on number of 'Explorer' daffodils
rooted per pot, 1974. . . . . . . . . 46

28. The influence of temperature and sampling time
treatments on the growth of roots (mm/bulb)
for 'Explorer' daffodil, 1973. . . . . . 48

29. The influence of preplanting treatments and
temperature on root growth (mm/bulb) for
'Explorer' daffodil, 1973 . . . . . . . 49

30. The influence of preplanting treatments and
sampling time on root growth (mm/bulb) for
'Explorer' daffodil, 1973 . . . . . . . 49

31. The influence of temperature and sampling time
treatments on root growth (mm/bulb) for
'Explorer' daffodil, 1974 . . . . . . . 50

32. The influence of preplanting treatments and
temperature on root growth (mm/bulb) for
'Explorer' daffodil, 1974 . . . . . . . 51

33. The influence of temperature and sampling time
treatments on root growth (g/bulb) for
'Explorer' daffodil, 1973 . . . . . . . 53

34. The influence of preplanting treatments and

temperature on root growth (g/bulb) for
'Explorer' daffodil, 1973 . . . . . . . 54

viii

Table

35.

36.

37.

The influence of preplanting treatments and
sampling time on root growth (g/bulb) for
'Explorer' daffodil, 1973 . . . . . .

The influence of temperature and sampling time
treatments on root growth (g/bulb) for
'Explorer' daffodil, 1974 . . . . . .

The influence of preplanting treatments and
temperature on root growth (g/bulb) for
'Explorer' daffodil, 1974 . . . . . .

Analysis of variance. Effects of temperature
and fungicide over time on number of bulbs
rooted.per pot, root length, and fresh root
weight. 'Paul Richter' Tulip, 1973. . .

Analysis of variance. Effects of temperature
and fungicide over time on number of bulbs
rooted per pot, root length, and fresh root
weight. 'Paul Richter' Tulip, 1974. . .

Analysis of variance. Effects of temperature
and fungicide over time on number of bulbs
rooted per pot, root length, and fresh root
weight. 'Pink Pearl' Hyacinth, 1973. . .

Analysis of variance. Effects Of temperature
and fungicide over time on number Of bulbs
rooted per pot,root length, and fresh root
weight. 'Pink Pearl' Hyacinth, 1974. . .

Analysis of variance. Effects of temperature
and fungicide over time on number of bulbs
rooted per pot, root length, and fresh root
weight. 'Explorer' Daffodil, 1973 . . .

Analysis of variance. Effects of temperature
and fungicide over time on number of bulbs
rooted per pot, root length, and fresh root
weight. 'Explorer' Daffodil, 1974 . . .

Analysis of variance. Effects of temperature
and fungicide over time on shoot develOpment.
'Paul Richter' Tulip, 1973 . . . . . .

Analysis of variance. Effects of temperature

and fungicide over time on shoot development.
'Paul Richter' Tulip, 1974 . . . . . .

ix

Page

54

55

56

75

76

77

78

79

80

81

82

Table

A-9.

A-lo o

A-ll c

A-12 0

Analysis of variance. Effects of
and fungicide over time on shoot
'Pink Pearl' Hyacinth, 1973 . .

Analysis of variance. Effects of
and fungicide Over time on shoot
'Pink Pearl' Hyacinth, 1974 . .

Analysis of variance. Effects of
and fungicide over time on shoot
'Explorer' Daffodil, 1973. . .

Analysis of variance. Effects Of
and fungicide over time on shoot
'Explorer' Daffodil, 1974. . .

temperature
develOpment.

temperature
development.

temperature
development.

temperature
development.

Page

83

84

85

86

LIST OF FIGURES

Figure Page

1. Effects of preplanting treatments, temperature,
and sampling time on root development of
'Paul Richter' tulips, 1974 . . . . . . 59

2. Effects of preplanting treatments, temperature,
and sampling time on root development of
'Explorer' daffodils, 1974 . . . . . . 61

3. Effects of preplanting treatments, temperature,
and sampling time on root development of
'Pink Pearl' hyacinths, 1974. . . . . . 64

4. A comparison of the root development after one
week of the preplanting treatments and the
control of 'Paul Richter' tulips at 17°C,
1974. . . . '. . . . . . . . . . 67

xi

I . LITERATURE REVIEW

Introduction

 

Many bulbous species are commercially forced to
produce high quality cut flowers and pot plants (De Hertogh,
1973). The first instance of scientific studies on forcing
bulbs was in 1909, when Nicholas Dames developed the
harvesting dates and a post harvest temperature sequence for
very early forcing of hyacinths (Hartsema, 1961). Because
each bulb Species is morphologically and genetically differ-
ent, Blaauw and his coworkers began to systematically
investigate the environmental requirements for development
of many of the important species (Hartsema, 1961). This
work has been continued by Rees (1972), De Hertogh (1974),
and others. Their research has demonstrated that almost
all species can be forced by precise control of the
environment, and in most instances, specifically temperature
control.

De Hertogh (1974) organized bulb forcing principles
into a three phase concept: production, programming, and
greenhouse phases. The production phase encompasses all
aspects related to field production of bulbs. The pro-

gramming phase comprises all handling of the bulbs from

harvest time until they are placed in the greenhouse. The
greenhouse phase is continued until the plants are developed
for marketing.

Rooting of bulbs is one of the prime factors in
both the production and programming phases. In the pro-
duction phase, bulbs are planted outdoors in October and
November and a good root system must be developed prior to
the onset of winter. In the programming phase Of standard
forcing, a series of controlled temperatures is necessary
not only to root the bulbs but also to satisfy the cold
requirement needed to Obtain shoot elongation. Briggs
(1972), de Pagter (1972), and De Hertogh (1973) have com-
piled the temperature sequences for satisfying the cold
requirement for many cultivars of tulips, hyacinths,
daffodils, and miscellaneous bulbs.

Beside temperature, there are several other
environmental factors which influence the initiation and
development of roots in bulbs. Among these are ethylene
(Kamerbeek and de Munk, 1976), bulb size and shape
(Schuurman, 1971), soil compaction in the field (de Haan,
et a1., 1971, and Wiersum, 1971), and the fungicide
benomyl (Raabe, 1970, and Thomas, 1973), Current research
on these and other factors will be summarized in this

review on the physiology of bulb rooting.

Factors Influencing Root Initiation
and Development

 

 

Temperature

 

Mulder and Luyten (1928) observed root formation
between September and October at the basal plate Of 'Pride
of Haarlem', a Darwin tulip. When the bulbs were received
in July, the basal plate, semi-circular in shape, had a
slightly projected broad, smooth surface. After storing at
17°C, the basal plate underwent enlargement, growing Out
4 to 6 mm. Roots subsequently emerged from this plate.

From 1920—27, Versluys (1927) conducted research on
the periodicity of the formation and growth of roots of

Hyacinthus orientalis L. 'Queen of the Blues'. Using

 

temperatures of 12.5, 16.5, 19.5, 23.5, and 27°C, she
determined that 23.5 and 27°C stimulated root initiation
but were detrimental to root elongation. She concluded
that 16.5°C was the best temperature for both root initiation
and elongation.

White (1940) using temperatures ranging from 11 to

28°C observed that precooled Lilium longiflorum Thunb.

 

'Giganteum' rooted for six weeks produced the best root
system in the range of 16 to 20°C. At higher or lower
temperatures, a poorer root system was produced. Hartley
(1968) Observed that there was no root growth at -1°C and
only limited growth at 4.5°C during the storage of 'Croft'
and 'Ace' Easter lilies, but considerable growth occurred

at 15.5, 21, and 27°C. Roots were found to be longest

at 21°C, but they were not as fibrous as those at 15.5°C.
De Hertogh and Blakely (1972) using temperatures of 5, 9,
13, 17, and 21°C found that nonprecooled 'Ace' lilies rooted
most rapidly at 21°C. However, Miller and Kiplinger (1966)
reported that temperatures above 20°C prior to cooling
could delay flowering and therefore De Hertogh and Blakely
(1972) concluded that a rooting temperature of 17°C should
be used in commercial practice. For precooled 'Ace'
lilies, the Optimal rooting temperature was found to be 17
to 21°C, and temperatures above 20°C should be avoided.
Shoub and De Hertogh (1975) determined the amount of
root growth at various stages in the forcing of 'Paul
Richter' tulips. They showed that root development (mg/
bulb/day) was greatest at 17°C during the greenhouse phase.
The next best root develOpment was observed after the bulbs
were planted and placed at 9°C during the programming
phase. They felt that root growth in general was more
optimal between 13 and 17°C but a definitive study of the
affect of temperature at each stage of root growth was not

conducted.

The Fungicide 'Benomyl'

 

Delp and Klopping (1968) reported that l-(butyl-
carbamoyl)-2-benzimidazole carbamic acid, methyl ester
(benomyl) has the unique characteristic of being a pre-
ventative, a curative, and a systemic fungicide as well as

being a mite ovicide. Benomyl has been demonstrated to be

effective against Botrytis spp., Fusarium spp., and

Penicillium Spp. which are diseases affecting tulips,

 

hyacinths, and daffodils. Edington, Knew, and Barron

(1971) showed that Botrytis, Fusarium, and Pencillium

 

 

were highly sensitive to 50 ppm of benomyl.
Raabe (1970) found that a mixture of benomyl and

ethazol protected 2. longiflorum roots from Pythium. With

 

increased disease control, he found that there was a corre-
sponding increase in root production. Lilies having a good
root system will not only grow better in the greenhouse but
will also have a better keeping quality in the home
environment. Bald et a1. (1973) reported that Easter lily
bulbs which were dipped for five minutes in 150 ppm of
benomyl before shipping, produced a healthier root system
after planting.

Schuft (1970) and Becker (1971) observed the effects
of benomyl on grapes which were not related to its fungicidal
properties. The effects, which appeared beneficial to vine
performance, included changes in bunch shape, fruit set,
berry weight, leaf shape, and shoot vigor. Becker suggested
that some of the changes resembled those induced by
cytokinins. Schruft pointed out that there were certain
chemical structural similarities between benomyl and
cytokinins. Skene (1972) conducted tests of benomyl
suSpensions in two cytokinin bioassays: the soybean callus

assay (Miller, 1968) and the radish cotyledon assay (Letham,

1968). Cytokinin-like activity of benomyl was thus con-
firmed by its positive effects in both assays.

Thomas (1973a) has reported that benomyl in com-
bination with a mixture of the gibberellins A4/7 caused
the breaking of seed dormancy of four celery cultivars.
Previously, Palevitch et a1. (1971) had shown celery seeds
to germinate under the influence of some cytokinins. Later,
Thomas (1973b) showed that benomyl possessed both cytokinin-
1ike and fungicidal activity. Skene (1972) suggested that
the effectiveness Of benomyl as a systemic fungicide was
related in some way to its cytokinin properties. He found
that fungicides showing the highest cytokinin activity were

the most phytotoxic ones.

Ethylene

Radin and Loomis (1969) reported that low concentra-
tions (0.01 ppm) of ethylene reduced growth of radish roots
by 50% and that at a higher concentration (1.0 ppm) growth
was completely inhibited. de Munk and de Rooy (1971) found

that 'Apeldoorn' tulips infected with Fusarium oxysporum

 

E. tulipae produced ethylene concentrations up to 10 ppm.
They observed that tulips planted adjacent to the infected
bulbs had reduced root growth and a high percentage of
flower blasting. When they passed 6 ppm ethylene through
the soil and in the air around the tulips which were not
Fusarium infected the growth Of shoots and roots were

totally inhibited. Flower buds were blasted and the shoots

were epinastic. The roots of the ethylene treated tulips
were also epinastic and produced an abundant amount of
protusions which were thought to be root hairs. Root hairs
are not normally present on tulips roots in the absence of
ethylene. There are many other anomalies observed in bulbs
due to the presence of ethylene. These have been reviewed

by Kamerbeek and de Munk (1976).

Soil Compaction

 

Wiersum (1971) has investigated the aeration
requirements of tulip roots. He found that the rate of
growth and penetration of the roots into compacted soils
was impeded. The restricted root growth impaired nutrient
uptake and lowered the supply of available moisture of the
bulb and shoot and crOp yield was reduCed. The longest
and healthiest roots were obtained in loose, well-aerated,
moist soil. de Hann and van der Valk (1971) also studied
root growth of several ornamental bulbs. They were con-
cerned with the effects of increased mechanical cultivation
and how it would influence crOp yield. At pore-volume
values 1eSS than 42%, root growth did not occur. They
Observed an increase in root penetration resistance. The
water and air content of the soil did not prohibit the
growth of roots and it was concluded that the decrease in
root growth was due to increased compaction. Wiersum
(1957) showed that from a mechanical point of View penetra-

tion was influenced not only by pore size but also by

 

 

rigidity of the pores. As long as the soil particles could
be displaced easily, the root tip could penetrate without
difficulty. They proposed that penetration resistance was

very strongly related to structural rigidity.

Bulb Size and Shape

 

Schuurman (1971) reported that root weight and root
length were linearly correlated to tulip bulb weight. He
showed that bulbs, although being of the same size grade,
gave different corresponding root weights. Nonmal shaped
bulbs (dry weight, 12 mg) produced 225 mg (dry weight) of
roots, while slighly flattened-radial shaped bulbs of the
same weight had 190 mg of roots. Strong flattened-radial
shaped bulbs had about 205 mg of roots. Since tulip roots
do not branch, he felt that the increase in tulip root
weight was due to number and length of the roots and that
other increases were due to increases in root diameter or

dry matter content.

Contractile Roots of Bulbous Species

 

It is a well established fact that the major
function of the root is to anchor the plant to the soil so
that water and nutrient uptake can occur (Esau, 1965).
Another important aspect of the anchorage of the plant to
the soil is by means of root contraction. Contraction
takes place during a certain stage of development of the
plant. The shoot apex is drawn near or below the ground

level and is placed in an optimal environment for growth

and for development of adventitous roots. Root contraction
is a common phenomenon and is widely distributed among
herbaceous perennial dictoyledons and monocotyledons
(Arber, 1925; Gravis, 1926; Rimbach, 1929).

Contractile roots are formed by the longitudinal
shortening and radial enlargement of the inner cortical
parenchyma cells, while the outer cells including the
cortical, exodermis, and epidermis are lifted over the
surface of the contractile region to form large wrinkles
(Chen, 1969). Contractile roots have been Observed in many
bulbous monocotyledons and function to draw the bulbs to
considerable depths in the soil (Chan, 1952). The con-

tractile region on Narcissus bulbs was found on the upper

 

portion of the root near the basal plate and usually
extended over more than 1 cm (Chen, 1969). Chan (1952)

reported that roots of Narcissus in March which had attained

 

a length of 3-7 cm were capable of contracting. In the
course of 4 to 5 weeks the roots became 7 to 8 mm shorter.
According to Wilson and Honey (1966), who studied

Hyacinth orientalis, the contraction of the inner cortical

 

cells was a growth process in which the radial walls of the
cells increased in area and thus the cells increased in
volume. They explained the changing of the shape of the
cells from a rectangle to a cuboid by means of active
growth of the upper and lower transverse walls, which

consequently extended the cell radially.

10

Chen (1969) reported that during the actual process
of contraction the radial expansion of the inner cortex
created a tension, tending to shorten both the outer cortex
and the stele. The pulling force was evidently greater than
the holding force and the rigidity of the outer cortex
which had more free space in which to move towards the
periphery of the root and thus was gathered into folds.

Sterling (1972), studying gladiolus roots, explains
that the driving force for contraction was the differ-
ential compressive stress between atmOSpheric pressure and

the negative pressure within the xylem.

I I . INTRODUCTION

For the past sixty years, bulb research has focused
mainly on floral develOpment and the cold requirement
needed for scape elongation and bulbing (Hartsema, 1961 and
Rees, 1972). These physiological responses have been found
to be mainly regulated by temperature. During the 1920s
and '303, Blaauw and co-workers studied_these areas
extensively. The area of root development, however, was
observed mainly as a secondary effect to floral develop-
ment. One major study was conducted by Versluys (1927) on

Hyacinthus orientalis L. 'Queen of the Blues'. She

 

Observed that 23.5 and 27°C were favorable for root
emergence from the basal plate but for root elongation
lower temperatures between 15 and 17°C were more favorable.
Another study by De Hertogh and Blakely (1972) on Lilium

longiflorum Thunb. 'Ace' showed that temperatures between

 

l7 and 21°C were Optimal for root growth of this Species.
Root develOpment iS a very important factor in the

forcing of bulbs. The major objective of this study was to

determine the Optimal temperature requirements for root

growth of tulips, hyacinths, and daffodils. A secondary

11

12

goal was to determine if the fungicides, benomyl and
ethazol, had a protective and/or stimulatory effect on the

rooting of bulbs, especially at the higher temperatures.

III. METHODS AND MATERIALS

Bulbs of Tulipa gesneriana L. 'Paul Richter',

 

Hyacinthus orientalis L. 'Pink Pearl' and Narcissus

 

 

pseudonarcissus L. 'Explorer' were received from the

 

Netherlands in mid-September 1973 and 1974. Upon arrival,
the bulbs were stored and handled as outlined in the
Holland Bulb Forcer's Guide (De Hertogh, 1973).

The following factors were common to the three bulb
Species during the experiments for 1973 and 1974. The pre-
planting fungicidal treatment consisted of a 30 minute dip
in a mixture of 0.2% benomyl and 0.4% ethazol. In 1974,
another preplanting dip of 30 minutes in tap water was
added. A steam sterilized planting medium consisting of
soil, peat and sand (1:1:1 by volume) was used. After the
initial postplanting watering, the bulbs were watered only
as needed to maintain a moist, well aerated medium. All
bulbs were rooted in dark, temperature controlled growth
chambers. No fertilizers were used. At the respective
sampling times, the soil was carefully washed from the
roots and the following parameters were measured: (1) number

of bulbs rooted per pot, (2) average root length (mm), and

13

14

(3) fresh root weight (g/bulb). The experiment was set up

as a completely randomized design.

Tulip

1973

After removal of the tunic, 450 tulip bulbs were
dipped in the fungicidal mixture and planted Six per 15
cm pot. After planting, 30 pots each of the control (non-
dipped) and fungicidal treated bulbs were placed at 5, 9,
13, 17, and 21°C. At weekly intervals for five weeks, three
pots of bulbs from each temperature and preplanting treat-

ment combination were sampled.

1974

The 1973 temperature and sampling time treatments
were used, but another preplanting treatment consisting of
the water dip was added. This study was conducted to
determine if the fungicidal treatment was having a cytokinin-
1ike effect on the bulbs, or if hydration was the major
factor. The number of replications and parameters measured

were the same as in 1973.

Hyacinth

1973
After the fungicidal dip, the hyacinths were
planted three per 15 cm pot. After planting, 30 pots of

each preplanting treatment were placed at 9, 13, 17, 21,

15

25, 29, or 33°C. Again, three pots from each temperature
and preplanting treatment combination were sampled at

weekly intervals.

1974
The 30 minute preplanting water dip was added and
the sampling date was changed to every five days over a 25

day period instead of weekly.

Daffodil

1973

Small Slabs and old roots were removed before
planting three per 15 cm pot. Thirty pots each of the
control and fungicidal dipped bulbs were placed at 5, 9,
l3, 17 or 21°C. Three pots of bulbs from each temperature
and preplanting treatment combination were sampled at

weekly intervals.

1214

The 1973 temperature and sampling dates were used,
and the 30 minutes preplanting water dip was added. A
larger pot (20 cm) was used so that Slabs did not have to
removed. In the previous year it was observed that roots

formed quickly in the area where Slabs had been removed.

IV . RESULTS

The analyses of variance for all experiments are
presented in the Appendix. Individual tables Show results
for 1973 and 1974 for the tulip (Appendix Tables 1 and 2),
hyacinth (Appendix Tables 3 and 4), and daffodil (Appendix
Tables 5 and 6). The analysis of variance was computed
for the following parameters: (1) number of bulbs rooted
per pot, (2) average root length (mm), and (3) fresh root
weight (9). Only the Significant first order interactions
will be discussed. Tukey's omega-procedure was used for
mean separation on the first order interactions at the 5%
level Of Significance. These results are presented in

Tulip 'Paul Richter'

 

Number of Bulbs Rooted per Pot

 

1973. At 9, 13, and 17°C, 100% of the bulbs rooted
within three weeks (Table 1). At 5°C, four weeks were
required while 21°C remained subOptimal throughout the five

week sampling period. The fungicidal dip resulted in an

16

17

Table l.--The influence of temperature and sampling time
treatments on number of 'Paul Richter' tulips

rooted per pot, 1973.x

 

Temperature (°C)y

 

 

 

Time Week
(weeks’ 5 9 13 17 21 Means
1 1.5a 3.5b 1.8a 2.8b 1.8a 2.3
e e e e ef
2 3.3b 5.8d 4.8c 5.3cd 1.3a 4.1
f f f f e
3 5.7b 6.0b 6.0b 6.0b 2.3a 5.2
g f g f f9
4 6.0b 6.0b 6.0b 6.0b 3.0a 5.4
9 f g f 9h
5 6.0b 6.0b 6.0b 6.0b 3.3a 5.5
g f g f h
Temperature
Means 4.5 5.5 4.9 5.2 2.4

 

xThere were six bulbs per pot.

yMeans in rows followed by the same letter (a to c)
and means in columns followed by the same letter (e to h)
are not significantly different at the 5% level.

18

increase in the number of bulbs which rooted only during
the first two weeks (Table 2).

1213. At 9 and 13°C, 100% of the bulbs rooted
within two weeks; whereas three weeks were required at 5
and 17°C (Table 3). Again, 21°C remained a suboptimal

temperature throughout the five week growth period.

Average Root Length (mm)

 

1111. After two weeks, 17°C was the optimal
temperature for root growth, but after three weeks, 9, 13,
and 17°C were not Significantly different (Table 4). At
the five week sample period, 13°C produced the longest root
system. The benomyl-ethazol dip increased root length at
21°C, and this was due to disease protection (Table 5).
There was no Significant difference between treated and
untreated bulbs at the other temperatures. The fungicides
did increase root length during the first three weeks when
averaging all temperatures (Table 6). However, after
three weeks, there were no Significant differences.

1315. After the first week of rooting, tulip bulbs
at 21°C produced the longest roots (Table 7). However,
after three weeks 17°C was Optimal and it remained so up
to week five. The fungicides did not increase root
elongation at the lower temperatures, but at 17 and 21°C
they were stimulatory (Table 8). The water dip also helped
root elongation at all temperatures except at 13°C. After
five weeks, both the water and fungicidal dips were better

than the control when averaging all temperatures (Table 9).

19

Table 2.--The influence of preplanting treatments and
sampling time on number of 'Paul Richter' tulips
rooted per pot, 1973.x

 

Time (Weeks)y

 

 

 

Preplanting Temperature
Treatments 1 2 3 4 5 Means
Control 0.9a 3.4b 5.1c 5.3c 5.7c 4.1

e e e e e
Fungicidal 3.7a 4.9b 5.3b 5.5b 5.3b 4.9
Dip f f e e e
Week 2.3 4.1 5.2 5.4 5.5

 

xThere were six bulbs per pot.

yMeans in rows followed by the same letter (a to c)
and means in columns followed by the same letter (e to f)
are not Significantly different at the 5% level.

20

Table 3.--The influence of temperature and sampling time
treatments on the number of 'Paul Richter' tulips
rooted per pot, 1974.x

 

Temperature (°C)y

 

 

 

Time Week
(Weeks) 5 9 13 17 21 Means
1 2.3a 4.1b 5.0b 4.4b 2.4a 3.7
e e e e e
2 5.9b 6.0b 6.0b 5.3b 3.1a 5.3
f f e ef ef
3 6.0b 6.0b 6.0b 6.0b 3.7a 5.5
f f e f f
4 6.0b 6.0b 6.0b 6.0b 4.1a 5.6
f f e f f
5 6.0b 6.0b 6.0b 6.0b 3.4a 5.5
f f e f ef
Temperature
Means 5.2 5.6 5.8 5.6 3.4

 

xThere were Six bulbs per pot.

yMeans in rows followed by the same letter (a to c)
and means in columns followed by the same letter (e to h)

are not Significantly different at the 5% level.

21

Table 4.--The influence of temperature and sampling time
treatments on the growth of roots (mm/bulb) for
'Paul Richter' tulip, 1973.

 

Temperature (°C)x

 

 

 

Time Week
(Weeks) 5 9 13 17 21 Means
1 1a 3a 3a 8a 18a 6.6
e e e e e
2 3a 27b 18ab 47c 26b 24.2
e f e f f
3 12a 66c 73c 74c 36b 52.2
ef g f g fg
4 28a 88c 91c 66b 47ab 64.0
fg h f fg gh
5 40a 108c 130d 95c 66b 81.4
g i g h h
Temperature 16.8 58.4 63.0 58.0 38.6
Means

 

xMeans in rows followed by the same letter (a to c)
and means in columns followed by the same letters (e to h)
are not significantly different at the 5% level.

22

Table 5.--The influence of preplanting treatments and
temperature on growth of roots (mm/bulb) for
'Paul Richter' tulip, 1973.

 

 

 

Preplanting Temperature (°C)x Preplanting
Treatments Treatments
5 9 13 17 21 Means
Control ~ 17a 60b 61b 54b 28a 44.0
e e e e e
Fungicidal 17a 57bc 65c 62bc 50b 50.2
Dip e e e e d

 

Temperature 17.0 58.5 63.0 58.0 39.0
Means

 

xMeans in rows followed by the same letter (a to c)
and means in columns followed by the same letter (e to d)
are not Significantly different at the 5% level.

Table 6.--The influence of preplanting treatments and
‘ sampling time on the growth of roots (mm/bulb)
for 'Paul Richter' tulip, 1973.

 

 

 

 

Preplanting Time (Weeks)x Preplanting
Treatments Treatments
1 2 3 4 5 Means
Control 1a 17b 48c 63d 89e 43.6
9 9 9 9 9
Fungicidal 12a 31b 56c 65c 87d 50.2
Dip h h h 9 9
Week 6.5 24.0 57.0 364.0 88.0
Means

 

xMeans in rows followed by the same letter (a to e)
and means in columns followed by the same letter (9 to h)
are not Significantly different at the 5% level.

23

Table 7.--The influence of temperature and sampling time
treatments on the growth Of roots (mm/bulb) for

'Paul Richter' tulip, 1974.

 

Temperature (°C)x

 

 

 

Time Week
(Weeks) 5 9 13 17 21 Means
1 3a 3a 5a 14b 23 c 9.6
f f f f f
2 8a 13a 26b 50c 42c 27.8
f 9 9 9 9
3 20a 29b 62c 84c 59c 50.8
g h h h h
4 37a 56b 81d 93e 70c 67.4
h i i j i
5 58a 79b 93c 109d 72b 82.2
i j j j 1
Temperature 25.2 36.0 53.4 70.0 53.2
Means '

 

xMeans in rows followed by the same letter (a to e)
and means in columns followed by the same letter (f to j)
are not Significantly different at the 5% level.

24

Table 8.--The influence of preplanting treatments and
temperature on the growth of roots (mm/bulb) for
'Paul Richter' tulip, 1974.

 

 

 

 

Preplanting Temperature (°C)x Preplanting
Treatment Treatment

5 9 l3 17 21 Means

Control 25a 39b 54d 57d 46c 44.2
ef f e e e

Water Dip 28a 36b 53c 76d 54c 49.4
f ef e f f

Fungicidal 22a 33b 53c 77d 59c 48.8

Dip e e e f f

Temperature 25.0 36.0 53.3 70.0 53.0

Means

 

xMeans in rows followed by the same letter (a to d)
and means in columns followed by the same letter (e to f)
are not Significantly different at the 5% level.

25

Table 9.--The influence of preplanting treatments and
sampling time on the growth of roots (mm/bulb)
for 'Paul Richter' tulip, 1974.

 

 

 

 

Preplanting Time (Weeks)x Preplanting
Treatments Treatments
1- 2 3 4 5 Means
Control 9a 24b 47c 62d 79e 44.2
f f f f f
water Dip I 9a 27b 55c 72d 85e 49.6
f f9 9 9 9
Fungicidal 10a 32b 51c 68d 83e. 48.8
Dip f g fg g fg
Week 9.3 27.7 51.0 67.3 82.3
Means

 

xMeans in rows followed by the same letter (a to e)
and means in columns followed by the same letter (f to g)
are not significantly different at the 5% level.

26

Fresh Root Weight (g/bulb)

 

1212. After three weeks, bulbs at 9, l3, and 17°C
produced good root growth. Within the five week rooting
period, 13°C was the Optimal temperature with 9 and 17°C
being Slightly suboptimal. .Temperatures 5 and 21°C were
not conducive to good root growth (Table 10). When com-
paring the fungicide treatment with the control, over time,
they were not Significantly different until the fifth week
(Table 11).

1212. The optimal temperature throughout the five
week period was 17°C with 13°C being the next best temper-
ature followed by 9°C (Table 12). Temperatures 5 and 21°C
remained suboptimal for root growth throughout the five
weeks. The fungicidal dip increased root growth at 17 and
21°C but did not increase it at the lower temperatures

(Table 13). The water dip was effective only at 17°C.
Hyacinth 'Pink Pearl'

Number of Bulbs Rooted per Pot

1212. The fungicidal dip had varying effects on
the number of hyacinths rooted per pot (Table 14). At 9,
25, and 33°C the fungicide increased the number rooted,
whereas at 29°C the control gave better rooting.

1212. There was no temperature or preplanting dip

effect on the number of bulbs rooted.

27

Table 10.--The influence of temperature and sampling time

treatments on the growth of roots (g/bulb) for
'Paul Richter' tulip, 1973.

 

Temperature (°C)x

 

 

 

Time Week
(Weeks) 5 9 13 17 21 Means
l 0.02a 0.15a 0.09a 0.25a 0.41a 0.18
e e e e e
2 0.10a 1.6lab 0.92a 3.05b 1.05a 1.35
e e f f e
3 0.74a 5.31b 6.60b 5.19b 1.11a 3.79
ef f 9 9 e
4 2.35a 7.21b 9.64c 6.95b 1.79a 5.59
£9 9 h h e
5 2.97a 9.90c 12.07d 9.63c 4.99b 7.91
g h i i f
Temperature 1.24 4.84 5.86 5.01 1.87
Means

 

xMeans in rows followed by the same letter (a to d)

and means in columns followed by the same letter (e to i)
are not significantly different at the 5% level.

28

Table 11.--The influence of preplanting treatments and
sampling time on root growth (g/bulb) for 'Paul
Richter' tulip, 1973.

 

 

 

 

Preplanting Time (Weeks)x Preplanting
Treatments Treatment
1 2 3 4 5 Means
Control .04a .95a 3.90b 5.50c 8.6d 3.80
f f f f g
Fungicidal .33a 1.74b 3.69c 5.68d 7.22e 3.73
Dip f f f f f
Week 0.19 1.35 3.80 5.59 7.91
Means

 

xMeans in rows followed by the same letter (a to e)
and means in columns followed by the same letter (f to g)
are not Significantly different at the 5% level.

29

Table 12.--The influence of temperature and sampling time
treatments on root growth (g/bulb) for 'Paul
Richter' tulip, 1974.

 

 

 

 

Time Temperature (°C)x .Week
(Weeks) Means
' 5 9 13 17 21
l 0.05a 0.07a 0.21a 0.54a 0.50a 0.27
f f f f f
2 0.48a 0.92ab 1.92abc 3.29c 1.95bc 1.71
f fg g 9 f9
3 1.40a 2.14a 5.35b 7.52c 2.84a 3.85
f g h h gh
4 3.07a 5.22b 8.74c 8.99c 3.56a 5.92
g h i i h
5 5.01b 8.51c 10.84d 13.76e 3.23a 8.27
h i j 3' 9h
Temperature 2.00 3.37 5.41 6.82 2.42
Means

 

xMeans in rows followed by the same letter (a to e)
and means in columns followed by the same letter (f to j)
are not Significantly different at the 5% level.

30

Table l3.--The influence of preplanting treatments and
temperature on root growth (g/bulb) for 'Paul
Richter' tulip, 1974.

 

 

 

 

Preplanting Temperaturex Preplanting
Treatments Treatments
5 9 l3 17 21 Means
Control 1.90a 3.70b 5.46c 5.01c 1.77a 3.57
e e e e e
Water Dip 2.36ab 3.28b 5.34c 7.51d 2.18a 4.13
e e e f e
Fungicidal 1.74a 3.14b 5.45c 7.94d 3.30b 4.31
Dip e e e f f
Treatment 2.00 3.37 5.42 6.82 2.42
Means

 

xMeans in rows followed by the same letter (a to d)
and means in columns followed by the same letter (e to g)

are not significantly different at the 5% level.

31

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.uom Hum OOHSO m Ohms muonax

 

 

 

 

 

memos
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amass: Dru so OHSOMHOOEOO poo OOSOEUOOHO mswusmamoum mo OOSOSHmsfi Ooaln.va OHOMB

32

Average Root Length (mm)

 

1212. After three weeks, bulbs at 17, 21, and 25°C
had the longest roots (Table 15). However, after four weeks,
bulbs at 17°C had Significantly longer roots. Root growth
of bulbs at 9, 29, and 33°C remained subOptimal even after
five weeks. The fungicidal dipped bulbs had increased
root growth at all temperatures except l3 and 17°C. This
effect could have been due to disease protection (Table 16).
The fungicide treated bulbs produced longer roots over time.
After the first week, the control and fungicide treated
bulbs did not show a difference, but after the second week
there was a Significant difference (Table 17).

1212. After the first five days, 21 and 25°C were
optimal growing temperatures. However, after ten days the
optimal temperature range included 17°C (Table 18). Nine
and 33°C remained subOptimal temperatures for root growth.
The fungicidal treatment increased root growth only at
21°C and did not show a significant difference at the
other temperatures (Table 19). The water dip was in-
effective. The fungicide or water treated bulbs showed an
increase in root growth only after 10 and 20 days when

averaged across all temperatures (Table 20).

Fresh Root We1ght (g/bulb)

 

1973. The best root growth occurred in the temper-

ature range of l7-25°C for the first four weeks, however,

33

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35

Table l7.--The influence of preplanting treatments and

sampling time on root growth (mm/bulb) for
'Pink Pearl' hyacinth, 1973.

 

 

 

 

Preplanting Time (Weeks)x Preplanting
Treatments Treatment
1 2 3 4 5 Means
Control 32a 55b 84c 82c 85c 67.6
d d d d d
Fungicidal 37a 70b 94c 98c 103C 80.4
d e e e e
Week Means 34.5 62.5 89.0 90.0 94.0

 

xMeans in rows followed by the same letters (a to c)
are means in columns followed by the same letters (d to e)
are not Significantly different at the 5% level.

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36

 

 

 

 

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38

Table 20.--The influence of preplanting treatments and
sampling time on the growth of roots (mm/bulb)
for 'Pink Pearl' hyacinth, 1974.

 

 

 

 

Preplanting Time (Days)x Preplanting ‘
Treatments Treatment
5 10 15 20 25 Means
Control 21a 48b 60c 77d 92e 61.4
f f f f f
Water Dip 24a 54b 69c 86d 92e 65.0
f f f g f
Fungicidal 25a 54b 70c 82d 96e 65.4
Dip f g f fg f
Day 23.3 52.0 69.3 81.7 93.3
Means

 

xMeans in rows followed by the same letter (a to e)
and means in columns followed by the same letter (f to g)
are not Significantly different at the 5% level.

39

after the fifth week 21 and 25°C were Optimal (Table 21).
Temperatures 9, 29, and 33°C remained subOptimal for root
growth. The fungicidal treatment enhanced root weight at
the fourth and fifth weeks of growth when all temperatures
were averaged (Table 22).

1212. After the first fifteen days of growth,
bulbs growing at 17, 21, and 25°C had greater root weight
than did bulbs at the other tempertures (Table 23). Bulbs
at 17 and 25°C produced the best root growth after 25 days,
while develOpment at 21°C was slightly less. The fungicidal
and water dips did not enhance root growth at any of the

temperatures (Table 24).

Daffodil 'Explorer‘

 

Number of Bulbs Rooted per Pot

 

1212. After two weeks, 100% of the bulbs rooted
at 13°C (Table 25). Within three weeks, 9°C rooted bulbs
obtained 100%. Bulbs at 17°C rooted rapidly but never
achieved 100%. At 5°C, it took five weeks to Obtain
a high percentage of rooted bulbs. A high percentage of
rooted bulbs was never Obtained throughout the five week
period at 21°C. The fungicidal dip increased the percent
rooting only at 21°C (Table 26).

.1212. After the first week, bulbs grown at 17°C
exhibited 100% rooting and within three weeks all bulbs
at 5, 9, and 13°C had rooted (Table 27). Bulbs at 21°C

never exhibited a high percentage of rooting.

4O

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em.ea mme.m em~.e oeeo.ee oom.ee ooe.ee neem.ea mam.e m
e e e e e m m
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O O O O O O O
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41

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42

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43

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44

Table 25.--The influence of temperature and sampling time

treatments on number of 'Explorer' daffodils
rooted per pot, 1973.x

 

 

 

 

Time Temperature (°C) Y Week
(Weeks) Means
5 9 13 17 21
1 1.2a 2.0ab 2.7b 2.7b 2.0ab 2.1
d d d d d
2 1.0a 2.8b 3.0b 2.5b 2.3b 2.3
d d d d d
3 2.0ab 3.0b 3.0b 2.7b 1.5a 2.4
de d d d d
4 2.3ab 3.0b 2.8b 2.8b 1.7a 2.5
ef d d d d
5 2.8ab 3.0b 3.0b 2.8ab 1.8a 2.7
f d d d d
Temperature 1.9 2.8 2.9 2.7 1.9
Means

 

xThere were 3 bulbs per pot.

yMeans in rows followed by the same letter (a to b)

and means in columns followed by the same letter (d to f)
are not Significantly different at the 5% level.

45

Table 26.--The influence of preplanting treatments and
temperature on number of 'Explorer' daffodils
rooted per pot, 1973.x

 

 

 

 

Preplanting Temperature (°C)y Preplanting
Treatment Treatment
5 9 l3 17 21 Means
Control 2.0a 2.9b 2.9b 2.7b 1.5a 2.4
e e e e e
Fungicidal 1.7a 2.7bc 2.9c 2.7bc 2.2ab 2.4
Dip e e e e f
Temper- 1.9 2.8 2.9 2.7 1.9

ature Means

 

xThere were 3 bulbs per pot.

yMeans in rows followed by the same letter (a to c)
and means in columns followed by the same letter (e to f)
are not significantly different at the 5% level.

Table 27.-—The influence of temperature and sampling time

1974.x

treatments on number of 'Explorer' daffodils
rooted per pot,

 

 

 

 

Time Temperature (°C)y Week
(Weeks) Means
5 9 l3 17 21
l 0.0a 0.0a 1.4b 3.0c 0.2a 0.9
e e e f ef
2 2.4b 3.0c 2.8c 3.0c 0.2a 2.3
f f f f ef
3 3.0b 3.0b 3.0b 3.0b 0.5a 2.5
g f f f f
4 3.0b 3.0b 3.0b 2.8b 0.1a 2.4
g f f f e
5 3.0b 3.0b 3.0b 3.0b 0.0a 2.4
g f f f e
Temperature 2.9 2.4 2.6 3.0 0.2
Means

 

xThere were 3 bulbs per pot.

yMeans in rows followed by the same letter (a to c)
and means in columns followed by the same letter (e to g)
are not significantly different at the 5% level.

47

Average Root Length (mm)

 

1212. After the first week, bulbs at 17 and 21°C
produced longer roots than at other temperatures (Table 28).
By the third week, the Optimal range Shifted down to 13 and
17°C and remained at these temperatures up to week five.
Five and 9°C were subOptimal temperatures for root growth.
The effect of the fungicides on root growth varied with the
temperature (Table 29). There was no difference between
the control and fungicide treated bulbs at 5, 13, and 17°C.
At 9°C, the control bulbs had better root development than
the fungicide treated bulbs, but at 21°C the Opposite
effect was observed. The fungicide treatment increased root
length during the five week sampling period (Table 30).
Greater root development was observed for the fungicide
treated bulbs after 2, 3, and 5 weeks.

1212. After each sampling period, it was deter-
mined that bulbs at 17°C had the longest roots (Table 31).
Bulbs grown at 13°C exhibited satisfactory root growth but
it was less than that at 17°C. Five and 21°C were sub-
0ptimal rooting temperatures. The fungicidal and water
treatments had an effect only at 13°C (Table 32). Bulbs at
other temperatures did not exhibit any difference between
the control, and preplanting water and fungicidal dip

treatments.

48

Table 28.--The influence of temperature and sampling time
treatments on the growth of roots (mm/bulb) for
'Explorer' daffodil, 1973.

 

Temperature (°C)x

 

 

 

Time Week
(Weeks) 5 9 13 17 21 Means
1 2a 5a 7a 16ab' 23b 10.6
e e e e e
2 2a 10a 18ab 3lbc 42c 20.6
e ef e e f
3 3a 26b 50c 55c l9ab 30.6
6 £9 f f e
4 8a 32b 67c 66c 31b 40.8
e gh g fg ef
5 15a 43b 80c 72c 46b 51.2
e h 9 9 f
Temperature 6.0 23.2 44.4 48.0 32.2
Means

 

xMeans in rows followed by the same letter (a to c)
and means in columns followed by the same letter (e to g)
are not significantly different at the 5% level.

49

Table 29.-~The influence of preplanting treatments and
temperature on root growth (mm/bulb) for
'Explorer' daffodil, 1973.

 

 

 

 

Preplanting Temperature (°C)x Preplanting
Treatment Treatment
5 9 13 17 21 Means
Control 7a 29c 46d 46d 20h 29.6
e f e e e
Fungicidal 5a 18d 43c 50c 44c 32.0
Dip e e e e f
Temperature 6.0 23.5 44.5 48.0 34.0
Means

 

xMeans in rows followed by the same letter (a to c)
and means in columns followed by the same letter (e to f)
are not significantly different at the 5% level.

Table 30.--The influence of preplanting treatments and
sampling time on root growth (mm/bulb) for
'Explorer' daffodil, 1973.

 

 

 

 

Preplanting Time (Weeks) Preplanting
Treatments Treatment
1 2 3 4 5 Means
Control 13a 18a 28b 40c 48d 29.4
e e e e e
Fungicidal 9a 23b 33c 41d 54e 32.0
Dip e f f e f
Week 11.0 20.5 30.5 40.5 51.0
Means

 

xMeans in rows followed by the same letter (a to d)
and means in columns followed by the same letter (e to f)
are not Significantly different at the 5% level.

50

Table 31.--The influence of temperature and sampling time
on root growth (mm/bulb) for 'Explorer'
daffodil, 1974.

 

Temperature (°C)x

 

 

 

Time week
(Weeks) 5 9 13 17 21 Means
1 0a 0a 3ab 17b Sab 5.0
9 9 9 9 9
2 4a 9ab 23b 53c 6a 19.0
g gh h h g
3 11a 22ab 48c 90d 37bc 41.6
gh h i i h
4 19a 52b 72c 104d 11a 51.6
hi i j ij 9
5 28b 72c 89a ll7e 0a 61.2
i J' k 3' 9
Temperature 12.4 31.0 47.0 76.2 11.8
Means ‘

 

xMeans in rows followed by the same letter (a to e)
and means in columns followed by the same letter (9 to k)
are not Significantly different at the 5% level.

51

Table 32.--The influence Of preplanting treatments and
temperature on root growth (mm/bulb) for
'Explorer' daffodil, 1974.

 

 

 

Preplanting Temperature (°C)x Preplanting
Treatments Treatment
5 l9 l3 17 21 Means
Control 13a 28b 38b 74c 16a 33.8
e e e e e
Water Dip 12a 29b 50c 74d 9a 34.8
e e f e e
Fungicidal 12a 36b 52c 81d 11a 38.4
Dip e e f . e e

 

Temperature 12.3 31.0 46.7 76.3 12.0
Means

 

xMeans in rows followed by the same letter (a to d)
and means in columns followed by the same letter (e to f)
are not Significantly different at the 5% level.

52

Fresh Root Weight (g/bulb)

 

1212. After one week, there was no significant
difference between any of the temperatures (Table 33).
After the third and fourth weeks, 13 and 17°C were Optimal
rooting temperatures. After the fifth week, 13°C became
optimal. Temperatures 5, 9, and 21°C were suboptimal for
rooting compared to the growth at 13 and 17°C. Fungicidal
treated bulbs at 5, 9, and 17°C showed no increase in root
growth as compared to the control (Table 34). At 9°C, the
control bulbs had more growth than did the fungicide
treated bulbs. At 21°C, the fungicidal treated bulbs
exhibited better root growth. After the fifth week, the
fungicidal treated bulbs had significantly better root
growth than the untreated bulbs when all temperature
treatments were averaged (Table 35).

1212. Throughout the five week period bulbs at
17°C-exhibited the best root growth (Table 36). Five and
21°C were suboptimal rooting temperatures. The fungicidal
treatment increased root growth at 9 and 13°C (Table 37).
Water dipped bulbs also Showed a significant difference

compared to the control bulbs at 13°C.

53

Table 33.--The influence of temperature and sampling time

treatments on root growth (g/bulb) for 'Explorer’

 

 

 

 

daffodil, 1973.
o x
Time Temperature ( C) Week
(weeks) 5 9 13 17 21 Means
1 0.00a 0.02a 0.08a 0.28a 0.10a 0.12
e e e e e
2 0.01a 0.58a 1.60a 2.23a 0.30a 0.94
e ef e f e
3 0.09a 2.42a 5.21b 6.39b 1.57a 3.14
e fg f, g e
4 0.78a 4.17b 8.26c 9.38c 4.73b 5.46
e gh g h f
5 1.16a 6.37b 14.15d 9.93c 6.55b 7.63
e h h h f
Temper- 0.51 2.71 5.86 5.64 2.65

ature Means

 

xMeans in rows followed by the same letter (a to d)
and means in columns followed by the same letter (e to h)
are not Significantly different at the 5% level.

54

Table 34.--The influence of preplanting treatments and
temperature on root growth (g/bulb) for
'Explorer' daffodil, 1973.

 

 

 

Preplanting Temperature (°C)x Preplanting
Treatment Treatment
5 9 13 17 21 Means
Control 0.45a 3.46b 6.24c 5.27c 0.55a 3.2
d e d d d
Fungicidal 0.37a 1.97b 5.48c 6.01c 4.75c 3.7
Dip d d d d e

 

Temperature 0.41 2.72 5.86 5.64 2.65
Means

 

xMeans in rows followed by the same letter (a to c)
and means in columns followed by the same letter (e to d)
are not significantly different at the 5% level.

Table 35.--The influence of preplanting treatments and
sampling time on root growth (g/bulh) for
'Explorer' daffodil, 1973.

 

 

 

 

Preplanting Time (Weeks)x Preplanting
Treatment Treatment
1 2 3 4 5 Means
Control 0.06a 0.84a 3.24b 5.07c 6.75d 3.19
e e e e e
Fungicidal 0.13a 1.06a 3.03b 5.86c 8.51d 3.72
Dip e e e e f
Week 0.10 0.95 3.14 5.47 7.63
Means

 

xMeans in rows followed by the same letter (a to d)
and means in columns followed by the same letter (e to f)
are not Significantly different at the 5% level.

55

Table 36.--The influence of temperature and sampling time

treatments on root growth (g/bulb) for 'Explorer'
daffodil, 1974.

 

 

 

 

Time Temperature (°C)x Week
(Weeks) Means
5 9 l3 17 21
1 0.00a 0.00a 0.09a 0.74a 0.49a 0.26
f f f f f
2 0.15a 0.58a 2.41a 6.3lb 0.15a 1.92
f fg f g f
3 0.84a 2.87a 8.18b 20.24c 2.66a 6.96
f g g h f
4 2.18a 10.32b 14.65c 28.27d 1.66a 11.42
fg h h i f
5 3.72b 15.61c 23.17d 37.92e 0.00a 16.08
9 i i j f
Temper- 1.38 5.88 9.70 18.70 0.99
ature
Means

 

xMeans in rows followed by the same letter (a to e)

and means in columns followed by the same letter (f to j)
are not significantly different at the 5% level.

56

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mneOE one Ao OD ev MODDOH Oeem OnD an oOSOHHOD OSOM nM mneOzx

 

 

 

 

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V . DISCUSSION

Van der Boon (1975) has demonstrated that tulip
roots had to be at least 50 mm in length before nitrogen
uptake could occur. Also, studies conducted here in
indicated that when using a 15 cm diameter pot, 70 mm of
root growth reached the bottom of the pot and subsequent
growth occurred around the periphery of the soil ball leading
to bound roots. Taking these facts into consideration, the
results of this study are discussed based on the assumption
that 70 mm of root growth is considered adequate for green-
house forcing of tulips, hyacinths, and daffodils.

The optimal temperature range for root development
of tulip and daffodil bulbs was found to be 13 and 17°C
(Fig. l and 2). The same rooting results were obtained in
1973 and 1974; thus indicating a consistent response for
two growing seasons. The tulip develOped a minimum of
70 mm of roots in 21 days in both years; whereas, the
daffodil required 35 days in 1973 and only twenty days in
1974 which is due to bulb variability from year to year.
The number of bulbs rooted per pot was also 100% or

Slightly less at these optimal temperatures and time

57

Figure l.

58

 

Effects of preplanting treatments, temperature,
and sampling time on root develOpment of 'Paul
Richter' tulips, 1974.

Fresh root weight (g/bulb) of the non-
dipped bulbs (control).

Fresh root weight (g/bulb) of the 30 minute
preplanting water dipping bulbs.

Fresh root weight (g/bulb) of the 30 minute
preplanting benomyl-ethazol dipped bulbs.

Root length (mm/bulb) of the non-dipped
bulbs (control).

Root length (mm/bulb) of the 30 minute
preplanting water dipped bulbs.

Root length (mm/bulb) of the 30 minute
preplanting benomyl-ethazol dipped bulbs.

 

 

 

 

 

 

 

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4““
w
an
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T U
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3.5m \3 52m; Door roux...

Figure 2.

60

Effects of preplanting treatments, temperature,
and sampling time on root development of
'Explorer' daffodils, 1974.

Fresh root weight (g/bulb) of the non-
dipped bulbs (control).

Fresh root weight (g/bulb) of the 30 minute
preplanting water dipped bulbs.

Fresh root weight (g/bulb) of the 30 minute
preplanting benomyl-ethazol dipped bulbs.

Root length (mm/bulb) of the non-dipped
bulbs (control).

Root length (mm/bulb) of the 30 minute
preplanting water dipped bulbs.

Root length (mm/bulb) of the 30 minute
preplanting benomyl-ethazol dipped bulbs.

FRESH ROOT WEIGHT (o/BULB)

 

 

 

 

 

 

 

61

A.
CONTROL
400:
am
300‘
250‘ — q,
20.05 _ ,5
ISO
IOO: ”'52
In
5.0 N‘
5 9 I3 I7 2I‘
TEMPERATURE ('0)
8.
WATER
40.0«
35.0:
300‘
250- .,
200‘ '
I50 09
I0.0< ”,9“
we
5 9 I3 I? 2I‘
TEMPERATURE re)
C.
BENOMYL a
ETHAZOL
40.0«
35.0:
soo-
250‘ b
20.0- 7 '
I50- .,
I0.0< ”57'
so —' we
:5 9 l3 "FF—2P

 

TEMPERATURE PC)

ROOT LENGTH (mm! BULB)

 

BENOMYL &

MOq
I20'
I00‘

30.

60-
40‘
20‘

 

 

5 9 I3 I7 2I‘

 
  
  

ETHAZOL

 

5 9'I3

 

 

l7 2| ‘
TEMPERATURE ('C)

62

periods. For the hyacinth, however, a higher optimal
temperature range of 17 to 25°C was required for rooting
(Fig. 3). In 1973, the hyacinth bulbs rooted at the
optimal temperature range produced 70 mm of roots within
14 days and in 1974 within 10 days. Also, 100% rooting
of the bulbs per pot occurred in this temperature range
within the 10 or 14 day period. The optimal temperatures
for root growth found in these experiments were higher
than those reported by Versluys (1927) for 'Queen of the
Blues' hyacinth.

The Optimal temperatures for root growth are
Similar to those for floral development for the reSpective
bulb Species. Luyten et al. (1925) found that 'Pride of
Haarlem' tulip placed at 17°C for two weeks or 13°C for
four weeks had optimal floral develOpment. Huisman and
Hartsema (1933) Showed that the Optimal temperature for
'King Alfred' daffodil for flower formation started at
20°C, but gradually dropped to 13°C. Hartsema (1961)
reported that the Optimal growth curve for both floral
development and root development of the hyacinth is
situated 4-5°C higher than the tulip. Luyten et a1.
(1932) found that 'L'Innocence' hyacinth formed flowers
best when given a few days at 34°C and then seven weeks at
25.5°C. The optimal temperature for root development of
the hyacinth, baSed on the studies conducted, appears

to be 4-8°C higher than that of the tulip or daffodil.

Figure 3.

63

Effects of preplanting treatments, temperature,
and sampling time on root development of 'Pink
Pearl' hyacinths, 1974.

Fresh root weight (g/bulb) of the non-dipped
bulbs (control).

Fresh root weight (g/bulb) of the 30 minute
preplanting water dipped bulbs.

Fresh root weight (g/bulb) of the 30 minute
preplanting benomyl-ethazol dipped bulbs.

Root length (mm/bulb) of the non-dipped
bulbs (control).

Root length (mm/bulb) of the 30 minute
preplanting water dipped bulbs.

Root length (mm/bulb) of the 30 minute
preplanting benomyl-ethazol dipped bulbs.

 

 

 

 

FRESH ROOT WEIGHT (9/ BULB)

 

64

ROOT LENGTH (mm/ BULB)

098833

 

 

 

 

EMPERATURE ('C)

 

65

And, this is in agreement with the earlier investigations
of Hartsema (1961).

The daffodil 'Explorer' did not root at 21°C in
these studies. However, when replanted and placed at 17°C
they rooted readily. Thus, 21°C was not lethal but did
inhibit root elongation. This temperature effect was not
observed with the tulip or hyacinth cultivars. This may
also be a possible mechanism for the daffodil to be pro-
tected when grown out of doors. When temperatures are 21°C
or above, the daffodil will not root and thus its roots will
not be exposed to diseases which are usually more prevalent
at higher temperatures.

The fungicidal pretreatments were used Since Raabe
(1970) had earlier found that as disease control increased
there was a corresponding increase in root production with
Easter lilies. With the tulip, it was observed that at
21°C the benomyl-ethazol preplanting dip promoted rooting
of many of the bulbs. Subsequently, in the 1974 study a
water dip was added to determine if the increase in root
length and weight was possibly due to a hydration phenomenon
or if it was a cytokinin-like effect as reported by Schuft
(1970), Becker (1971) and Thomas (l973a,b). It was found
that both the water and fungicidal dip were effective in
promoting rooting of tulips. A closer look at the bulbs
(Fig. 4) revealed that the fungicidal dip increased the
uniformity of rooting during the first week. This could

be useful when forcing special precooling tulips. For this

66

Figure 4. A comparison of the root development after

one week of the preplanting treatments and

the control of 'Paul Richter' tulips at 17°C,
1974.

67

PAUL RICHTER

VVIE£I( 1
1974

FUNGICIDE

NO
TRE ATMENT

 

68

particular type of forcing, tulip bulbs receive a dry

cold treatment and subsequently when planted in the green-
house they must undergo root and shoot elongation at the
same time. AS root develOpment is very crucial to pre-
cooled forcing, use of the fungicidal dip to promote
rooting and combat disease would be very beneficial.

AS far as root growth was concerned, the benomyl-
ethazol dip was observed to have the greatest effect on
the tulip. However, it did Slightly stimulate root
development in the hyacinth and daffodil. The principle
reason for employing a fungicide is to prevent disease.

AS these experiments were only conducted for a five week
period, it must be kept in mind that in order to force
bulbs they would have to receive a minimum of 14 cold weeks
to satisfy the subsequent low temperature requirement for
floral stalk elongation. With the extensive period of

time that is needed to fully program the bulbs, the systemic
fungicidal dip is bound to be effective for disease pro-
tection and thus result in overall higher quality plants.
Further experimentation Should be conducted on root
development in regards to the long term effects of the
fungicidal and water dips. The water dip was as effective
as the fungicidal treatment for root promotion in daffodil
and hyacinth bulbs, but after 15 weeks at the low temper—
ature required for forcing the shoot would the water dip

be as effective in disease control?

69

The results of this study are applicable in two
areas of future research. First, it is possible that
programs could be develOped for tulips, hyacinths, and
daffodils for very late forcing. The current forcing
sequences use a 15 to 23 week period beginning with 9°C
for rooting followed by 2-5°C for_cooling and shoot
retardation, depending on the desired date for flowering.
If a bulb receives more than 18-20 weeks of cold, it
becomes over-cooled and as a result stretching occurs which
results in a low quality pot plant. Therefore, 9 and 5°C
Should be considered cooling temperatures. If the bulbs
were initially rooted for four weeks at 17°C, a noncooling
temperature, and then given a cold treatment of 18 weeks,
a total of 22 weeks would be involved but only 18 weeks as
cold exposure. A marketable pot plant for late Spring
sales could be produced using this method. Continued
research is needed in this area to better formulate new
schemes for late forcing taking advantage of Optimal non-
cooling rooting temperatures.

Secondly, since it is possible to root the bulbs
at noncooling temperatures the cold requirement needed for
scape elongation and bulbing could be studied apart from
root development. Scape elongation and bulbing are under
hormonal regulation. The gibberellins are a controlling
class of hormones in the tulip (Aung and De Hertogh, 1971).
They observed that rooted tulips contained more total GA'S

than did unrooted bulbs and also, that tulips rooted at

70

9°C (a cooling temperature) contained more GA'S than did
bulbs rooted at 17°C (a noncooling temperature). Further
physiological studies Should be undertaken to understand
scape elongation and bulbing using 17°C as the rooting

temperature because less hormones are produced.

VII. LITERATURE CITED

Arber, A. 1925. Monogotyledons: A morphological study.
Cambridge University Press, Cambridge. 258 p.

Aung, L. H., and A. A. De Hertogh. 1971. The alteration
of bulb hormones content by environmental stimuli.
Acta. Hort. 23:156-161.

Bald, J. G., A. O. Paulus, and J. V. Lenz. 1973. Fungici-

3:1 dips for Easter lily bulbs. Calif. Agri.
:8-10.

 

Becker, H. 1971. Untersuchungen uber den Einsatz des
Fungizides Benomyl in der Rebensoeredlung. Wein-
Wissenschaft. 26:50-56.

Boon, J. Van der. 1972. Tijdstip van stikstofoPname door
de tulp. Stikstof. 71:459-465.

Briggs, J. B. 1972. Narcissus and Tulip forcigg.
Ministry of Agriculture, Fisheries andTFood.
Kirton Experimental Horticulture Station. Station
Leaflet NO. l, 41 p.

Chan, T. T. (S. Chen). 1952. The develOpment of the
Narcissus Plant. Daffodil Tulip Yearbook. 17:

Chen, S. 1969. The contractile roots of Narcissus.
Ann. Bot. 33:421-426.

 

De Hertogh, A. A. 1973. Hollang Bulb Forcers_Guide.
Netherlands Flower—buIB Institute and Dutch—Bulb
Exporters Association, New York. 300 p.

De Hertogh, A. A. 1974. Principles for forcing tulips,

hyacinths, daffodils, Easter Lilies and Dutch
irises. Scientia Hort. 2:313-355.

71

72

De Hertogh, A. A., and N. Blakely. 1972. The influence
of temperature and storage time on growth of basal
roots of nonprecooled and precooled bulbs of
Lilium longiflorum Thunb. cv. Ace. Hortscience.

 

 

Delp, C. J., and H. L. Klopping. 1968. Performance
attributes of a new fungicide and mite ovicide
candidate. Plant Disease Reporter. 52:95-99.

 

Edington, L. V.; K. L. Khew; and G. L. Barron. 1971.
Fungitoxic Spectrum of benzimidazole compounds.
Phytopathology. 61:42-44.

 

Esau, K. 1965. 21ant Anatomy. John Wiley and Sons,
New York. 767 p.

 

Gravis, A. 1926. Contribution a l'etude anatomique du
raccourcissement des racines. Acad. Roy; de Belg.,
Bul. de C1. des Sci. 12:48-69.

 

 

Haan, F. A. M., de and G. G. M van der Valk. 1971. Effects
of compaction on physical properties of soil and
root growth of ornamental bulbs. Acta. Hort.
23:326-332.

 

Hartley, D. E. 1968. Growth and flowering responses of
Easter lily, Lilium longiflorum Thunb., to bulb
storage. Ph.D. Tfiesis, Oregon State University,
Corvallis.

 

Hartsema, A. M. 1961. Influence of temperature on flower
formation and flowering of bulbous and tuberous
plants. EncyclOpedia Plant Physiology. 16:123-161.

 

Huisman, E., and A. M. Hartsema. 1933. The periodical
develOpment of Narcissus pseudonarcissus L. Med.
L.H.S. Wageningen. 37:1-55.

 

Kamerbeek, G. A., and W. J. de Munk. 1976. A review of
ethylene effects in bulbous plants. Scientia

Letham, D. S. 1968. A new cytokinin bioassay and the
naturally occurring cytokinin complex. In Biocheme
istry andphysio1ogy ofgplant growth substances.
pp. 19-31. Ed. F. Wightman and G. SEtteEerld}

The Runge Press, Ottawa.

73

Luyten, 1.; G. Joustra; and A. H. Blaauw. 1925. The
results of temperature treatment in summer for the
Darwin tulip. II. Proc. kon, ned. Adad. Wet.
29:113-126.

 

Luyten, I., M. C. Versluys, and A. H. Blaauw. 1932. The
optimal temperatures from flower formation to
flowering for Hyacinth orientalis. Proc. kon. ned.
Akad. Wet. 29:1-64.

I

 

 

Miller, C. O. 1968. Naturally-occurring cytokinins. In
Biochemistry and physiolo ofgplant growth sub-
stances. pp. 33;45. Ed. F. Wightman and G.
Setterfield. The Runge Press, Ottawa.

Miller, R. 0., and D. C. Kiplinger. 1966. Reversal of
vernallzatlon in Northwest Easter lilies. Proc.
Amer. Soc. Hort. Sci. 88:646-650.

 

Mulder, R,, and I. Luyten. 1928. De periodieke ontwik-
keling van de Darwin-tulip. verh. kon. ned. Akad.
Weten. 26:1-64.

 

Munk, W. J. de, and M. de Rooy. 1971. The influence of
ethylene on the development of 5°C precooled 'Apel-
doorn' tulips during forcing. Hortscience.

 

Pagter, J. W. A. de. 1972. Forcing Flower Bulbg. Nether-
lands Flower bulb Institute. Hillegom, The Nether-
lands. 64 p.

 

Palevitch, D.; T. H. Thomas; and R. B. Austin. 1971.
Dormancy-release of celery seed by a growth retard-
ent, N-dimethylaminosuccinamic acid (Alar).

Planta. 100:370-372.

Raabe, R. D., and J. Hurlimann. 1970. Fungicides for
control of Easter lily root rots. California
Agriculture. 24:14-15.

 

 

Radin, J. W., and R. S. Loomis. 1969. Ethylene and carbon
dioxide in the growth and development of cultured
radish roots. Plant Physiol. 44:1584-1589.

 

Rees, A. R. 1969. Effects of duration of cold treatment
on the subsequent flowering of tulips. J. Hort.
Sci. 44:27-36.

Rees, A. R. 1972. The Growth of Bulbs. Academic Press,
New York. 3117p.

 

74

Rimbach, A. 1929. Die Verbreitung der Wurzelverkurzung
un Pflamzeunich. Deut. Bot. Gesell. Ber. 47:22-31.

 

Schruft, G. 1970. Die Wirking des Botrytis - Praparates
Benomyl in Amaranthus-Cytokinin-Test. Wein-Wissen-
schaft. 25:329-333.

 

Schuurman, J. J. 1971. Effect of size and Shape of tulip
bulbs on root development. Acta. Hort. 23:312-317.

 

Shoub, J., and A. A. De Hertogh. 1975. Growth and develop-
ment of the shoot, roots, and central bulblet Of
Tulipa gesneriana L. cv. Paul Richter during
standard forcing. J. Amer. Soc. Hort. Sci.
100(1):32-37. '

Skene, K. G. M. 1972. Cytokinin-like properties of the
systemic fungicide benomyl. Jour. Hort. Sci.
47:179-182.

 

Sterling, C. 1972. Mechanism of root contraction in
Gladiolus. Ann. Bot. 36:589-598.

Thomas, T. H. 1973a. Growth regulatory effects of three
benzimidazole fungicides on the germination of

celery (A ium garaveoleus) seeds. Ann. appl. Biol.
74:233-235.

Thomas, T. H. 1973b. Investigations into the cytokinin-
1ike prOperties of benzimidazole-derived fungicides.
Ann. appl. Biol. 76:237-241.

Versluys, M. C. 1927. Aanleg en groti der wortels van
gyacinthus orientalis. Verh. kon. ned. Akad. Wet.
25:62-72.

White, H. E. 1940. The culture and forcing ongster
lilies. Mass. Agr. Expt. Sta. Bul. NO. 376.

Wiersum, L. K. 1957. The relationship of the size and
structural rigidity of pores to their penetration
by roots. Plant and Soil Ix. 1:75-85.

Wiersum, L. K. 1971. Tulip root behavior and aeration
requirements. Acta Hort. 23:318-325.

 

Wilson, K., and J. N. Honey. 1966. Root contraction in
Hyacinthus orientalis. Ann. Bot. 30:48-61.

APPENDIX

TABLES

Table A-1.--Analysis of variance. Effects of temperature
and fungicide over time on number of bulbs
rooted per pot, root length, and fresh root
weight. 'Paul Richter' Tulip, 1973.

 

Analysis of Variance

 

 

Measurement
Source 48 MS F

No. Rooted
Total 149
Temp (T) 4 46.58 x
Time-Weeks (W) 4 54.07 81.10***Y
T x w 16 3.11 4.66***
Fungicide (F) 1 28.17 42.25***
T X F 4 1.11 1.68
W x F 4 11.57 l7.35***
T X W x F 16 2.23 3.38***
Error 100 0.67

Root Length
Total 149
Temp (T) 4 11188.28 -
Time (W) 4 31059.79 193.30***
T X W 16 1755.98 10.93***
Fungicide (F) 1 1541.77 9.59***
T X F 4 687.15 4.28***
W X F 4 331.40 2.06*
T X W X F 16 227.99 1.42
Error 100 160.69

Root Weight
Total 149
Temp (T) 4 128.25 -
Time (W) 4 294.06 208.02***
T x W 16 19.11 13.52***
Fungicide (F) l 0.15 0.11
T x F 4 0.88 0.62
W x F 4 5.03 3.55***
T x W x.F 16 1.42 1.00
Error 100 1.41

 

xThe main effect, temperature, cannot be tested as
it was not replicated.

y *Significant at 10% level.
**Significant at 5% level.
***Significant at 1% level.

75

76

Table A-2.--Ana1ysis of variance.

Effects of temperature

and fungicide over time on number of bulbs
rooted per pot, root length, and fresh root

 

 

 

weight. 'Paul Richter' Tulip, 1974.
Analysis of Variance
Measurement
Source df MS F
No. Rooted
Total 224
Temp (T) 4 45.37 _x
Time-Weeks (W) 4 30.29 40.33..“1'
T X W 16 2.38 3.17***
Fungicide (F) 2 3.20 4.27**
T X F 8 1.17 1.56
W X F 8 0.79 1.06
T X W X F 32 0.73 0.97
Error 150 0.75
Root Length
Total 224
Temp (T) 4 1356.73 -
Time (W) 4 38636.45 746.44***
T X W 16 993.37 l9.19***
Fungicide (F) 2 612.87 ll.84***
T X F 8 535.70 10.35***
W x F 8 83.56 1.61*
T x W x F 32 118.41 2.29***
Error 150 51.76
Root weight
Total 224
Temp (T) 4 189.48 ‘
Time (W) 4 461.67 352.60***
T X W 16 28.58 21.83***
Fungicide (F) 2 11.41 8.71***
T X F 8 9.60 7.33***
W x F 8 1.29 0.99
T X W X F 32 1.96 1.49*
Error 150 1.31

 

xThe main effect, temperature cannot be tested as
it was not replicated.

Y

*Significant at 10% level.
**Significant at 5% level.
***Significant at 1% level.

77

Table A-3.--Ana1ysis of variance.
and fungicide over time on number of bulbs
rooted per pot, root length, and fresh root

Effects of temperature

 

 

 

weight. 'Pink Pearl' Hyacinth, 1973.
Measurement Analysrs of Variance
Source df MS F
No. Rooted
Total 209
Temp (T) 6 0.10 _x
Time-Weeks (W) 4 0.04 1.50y
T x W 24 0.04 1.31
Fungicide (F) l 0.17 6.00**
T x F 6 0.12 4.44***
W x F 4 0.03 1.00
T x W x F 24 0.04 1.39
Error 140 0.03
Root Length
Total 209
Temp (T) 6 6727.24 -
Time (W) 4 26749.48 l98.25***
T x W 24 1028.97 7.63***
Fungicide (F) 1 8115.86 60.15***
T X F 6 649.88 4.82***
W x F 4 277.86 2.06*
T x W x F 24 97.07 0.72
Error 140 134.93
Root Weight
Total 209
Temp (T) 6 316.58 -
Time (W) 4 1293.11 259.38***
T x W 24 33.11 6.64***
Fungicide (F) 1 180.98 36.30
T x F 6 6.70 1.34
W x F 4 33.16 6.65***
T x w x F 24 3.96 0.79
Error 140

4.99

 

xThe main effect, temperature cannot be tested as

it was not replicated.

Y *Significant at 10% level.
**Significant at 5% level.
***Significant at 1% level.

78

Table A-4.--Analysis of variance. Effects of temperature
and fungicide over time on number of bulbs
rooted per pot, root length, and fresh root

 

 

 

weight. 'Pink Pearl' Hyacinth, 1974.
Measurement Analysis of Variance
Source df MS F
No. Rooted
Total 314
Temp (T) 6 0.14 -X
Time-Days (D) 4 0.08 2.21*Y
T x D 24 0.02 0.65
Fungicide (F) 2 0.07 1.75
T x F 12 0.02 0.39
D x F 8 0.05 1.33
T x D x F 48 0.02 0.58
Error 210 0.04
Root Length
Total 314
Temp (T) 6 28517.26 -
Time-Days (D) 4 47431.08 1198.23***
T x D 24 827.28 20.90***
Fungicide (F) 2 496.97 12.55***
T x F 12 97.92 2.47***
D x F 8 94.68 2.39**
T x D x F 48 126.63 3.19***
Error 210 39.58
Root Weight
Total 314
Temp (T) 6 730.13 -
Time-Days (D) 4 935.56 374.70***
T x D 24 27.35 10.95***
Fungicide (F) 2 0.41 0.16
T x F 12 5.03 2.02**
D x F 8 3.85 1.54
T x D x F 48 3.55 l.42**
Error 210 2.50

 

xThe main effect, temperature

it was not replicated.

Y

*Significant at 10% level.

**Significant at 5% level.
***Significant at 1% level.

cannot be tested as

79

Table A-5.--Analysis of variance.
and fungicide over time on number of bulbs
rooted per pot, root length, and fresh root

Effects of temperature

 

 

 

weight. 'Explorer' Daffodil, 1973.
Measurement Analysis of Variance
Source df MS F
NO. Rooted
Total 149
Temp (T) 4 7.81 -x
Time-Weeks (W) 4 1.51 3.24**Y
T x W 16 1.03 2.20***
Fungicide (F) 1 0.01 0.01
T x F 4 1.06 2.26*
W x F 4 0.42 0.91
T x W x F 16 0.39 0.84
Error 100 0.47
Root Length
Total 149
Temp (T) 4 8625.69 -
Time (W) 4 7666.41 142.92***
T x W 16 990.14 18.46***
Fungicide (F) 1 200.91 3.75*
T x F 4 1318.74 24.59***
W x F 4 132.47 2.47**
T x W x F 16 162.94 3.04***
Error 100 53.64
Root Weight
Total 149
Temp (T) 4 157.85 -
Time (W) 4 293.62 137.49***
T x W 16 24.44 ll.44***
Fungicide (F) l 10.32 4.83*
T x F 4 36.90 17.27***
W x F 4 4.53 2.12*
T x W x F 16 ~9.10 4.26***
Error 100 2.14

 

xThe main effect, temperature cannot be tested as

it was not replicated.

y *Significant at 10% level.
**Significant at 5% level.
***Significant at 1% level.

80

Table A-6.--Analysis of variance.

Effects of temperature
and fungicide over time on number of bulbs
rooted per pot, root length, and fresh root

 

 

 

weight. 'Explorer' Daffodil, 1974.
Measurement Analyais of Variance
Source df MS F
No. Rooted
Total 224
Temp (T) 4 53.36 -x
Time-Weeks (W) 4 19.73 185.00***y
T x W 16 4.09 38.33***
Fungicide (F) 2 0.58 0.54
T x F 8 0.15 1.42
W x F 8 0.18 1.69*
T x W x F 32 0.18 l.66**
Error 150 0.11
Root Length
Total 224
Temp (T) 4 32696.17 -
Time (W) 4 24367.29 163.3l***
T x W 16 3259.84 21.85***
Fungicide (F) 2 459.43 3.07**
T x F 8 295.01 1.98**
W x F 8 60.69 0.41
T x W x F 32 141.57 0.95
Error 150 149.21
Root Weight
Total 224
Temp (T) 4 2390.86 -
Time (W) 4 1942.40 435.87***
T x W 16 354.94 79.65***
Fungicide (F) 2 20.93 4.70*
T x F 8 16.27 3.65***
W x F 8 5.14 1.16
T x W x F 32 4.43 0.99
Error 150 4.46

 

xThe main effect, temperature cannot be tested as
it was not replicated.

Y

*Significant at 10% level.
**Significant at 5% level.
***Significant at 1% level.

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Table A—9.--Analysis of variance. Effects of temperature
and fungicide over time on shoot develOpment.
'Pink Pearl' Hyacinth, 1973.

 

 

NO. Shoot Flower
Source df Shoots (mm) (mm)
Temp (T) 6 0.04 144.91 163.97*
Fungicide (F) l 0.02 1.77 10.39***
T'x F 6 0.09 5.53 4.64
Time (W) 4 0.14 663.90*** 743.37***
T x W 24 0.18 25.22*** 26.96***
F x W 4 0.13 4.20 2.66
T x F x W 24 0.14 3.97 3.41
Error 140 0.14 3.43 2.34

 

xThe main effect, temperature, cannot be teated as
it was not replicated.

YT - Test * Significant at the 5% level.
** Significant at the 1% level.
*** Significant at the 0.1% level.

84

Table A-10.--Analysis of variance. Effects of temperature
and fungicide over time on Shoot development.
'Pink Pearl' Hyacinth, 1974.

 

 

No. Shoot Flower
Source df Shoots (mm) (mm)
Temp (T) 6 0.07 171.23 128.97*
Fungicide (F) 2 0.08 2.14 3.74*
T x F 12 0.05 5.10 6.60
Time (W) 4 0.02 444.76*** 86.45***
T x W 24 0.05 15.34*** l4.66**
F x W 8 0.04 2.85 1.09
T x F x W 48 0.06 2.00‘ 1.86
Error 210 0.05 2.87 7.00

 

xThe main effect, temperature, cannot be tested as
it was not replicated.

yF - Test * Significant at the 5% level.
** Significant at the 1% level.
*** Significant at the 0.1% level.

85

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