THESIS

Date

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Liéégu’iflf

Michigan State
University

 

This is to certify that the

thesis entitled

The Use of TODD Planter Flats for Fresh
Market Tomato and Pepper Transplant Production

presented by

LESLIE A. WESTON

has been accepted towards fulfillment
of the requirements for

degree in Hort1culture

 

 

Dr. Bernard H. Zandstra

a [M Major professor

10/6/82 Secretary, Gralduatgiagtice/
Department of Horticulture

 

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THE USE OF TODD PLANTER FLATS FOR FRESH MARKET
TOMATO AND PEPPER TRANSPLANT PRODUCTION

By

Leslie Ann Weston

A THESIS

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

MASTER OF SCIENCE

Department of Horticulture

1982

ii

ABSTRACT

THE USE OF TODD PLANTER FLATS FOR FRESH MARKET
TOMATO AND PEPPER TRANSPLANT PRODUCTION

By

Leslie Ann Weston

Tomato (Lycqpersicon esculentum Mill.) and pepper
(Capsicwnannuum L.) transplants produced in two locations,
in several root cell sizes and of various ages, were
compared for productivity in Michigan. Plants grown in
larger cells were largest and produced highest early and
total marketable yields. Larger root cell size was more
critical in producing larger transplants than was wider
spacing in the flat. Four-tx>five-week—old tomato trans-
plants fertilized with high nitrogen and low phosphorus
produced larger early yields than plants of other ages and
fertilizer treatments. Tomato transplants grown in TODD
flats in Michigan produced larger early and total marketable
yields than transplants produced by Speedling in Florida.
Speedling tomato plants shipped by air freight to Michigan
produced less ethylene and CO2 than Michigan plants,

indicating little stress during shipment.

ACKNOWLEDGEMENTS

I would like to express my gratitude to Dr. B. Zandstra
for the assistance, guidance and support which made this
research possible. I would also like to thank the members
of my committee, Dr. D. Krauskopf, Dr. H. Price and Dr. D.
Warncke for their encouragement and helpful suggestions.

I owe many thanks to Julia Foster, Sheldon Furutani,
Lynne Crankshaw and Jim Oris for their help and moral support
during the various stages of this research.

I would also like to thank the Michigan Woman's Farm and
Garden Association and Marian Renaud for their support in
1981 and the Michigan Farm and Garden Foundation for their
support in 1982.

A final tribute must go to my husband, Paul, who helped
with field and greenhouse work and provided assistance,
encouragement and understanding during the past few months

of thesis writing.

iii

TABLE OF CONTENTS

Page
CHAPTER I
LITERATURE REVIEW
Introduction . . . . . . . . . . . . . . . . . . . . . 1
Summary. . . . . . . . . . . . . . . . . . . . . . . . 20
CHAPTER II
A COMPARISON OF THE EARLY GROWTH AND YIELD OF TOMATO AND
PEPPER TRANSPLANTS PRODUCED IN THREE DIFFERENT GROWING
CONTAINERS
Introduction . . . . . . . . . . . . . . . . . . . . . 23
Materials and Methods. . . . . . . . . . . . . . . . . 2U
Results. . . . . . . . . . . . . . . . . . . . . . . . 26
Discussion and Conclusions . . . . . . . . . . . . . . 28
CHAPTER III
STUDIES ON THE EFFECT OF ROOT CELL SIZE, PLANT SPACING AND
LOCATION OF PRODUCTION ON DEVELOPMENT AND YIELD OF TOMATO
AND PEPPER TRANSPLANTS
Introduction . . . . . . . . . . . . . . . . . . . . . 31
Materials and Methods. . . . . . . . . . . . . . . . . 33
Results. . . . . . . . . . . . . . . . . . . . . . . . A3
Discussion and Conclusions . . . . . . . . . . . . . . 102
CHAPTER IV
THE EFFECT OF NITROGEN AND PHOSPHORUS FERTILIZATION OF
PIK-RED TOMATO TRANSPLANTS AND THEIR DEVELOPMENT AND
YIELD IN THE FIELD
Introduction . . . . . . . . . . . . . . . . . . . . . lll

iv

Page

Materials and Methods . . . . . . . . . . . . . . . . 113
Results . . . . . . . . . . . . . . . . . . . . . . . 117
Discussion and Conclusions. . . . . . . . . . . . . . IAO
SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . 1A8

LITERATURE CITED. . . . . . . . . . . . . . . . . . . . 151

Table

Table

Table

Table

Table

LIST OF TABLES

Influence of containers on the size of Pik-Red
tomato seedlings grown at Michigan State

University at A weeks of age.

Influence of containers on the size of Lady
Bell pepper seedlings grown at Michigan State

University at A weeks of age.

Influence of containers on the yield of Pik-
Red tomato transplants grown at Michigan

State University.

Influence of containers on the yield of Lady
Bell pepper transplants grown at Michigan

State University.
Depth, area and volume of root cell size of
TODD planter flats produced by Speedling,

Inc.

vi

Page

27

27

28

28

A0

Table 6.

Table 7.

Table 8.

Table 9.

Table 10.

Tab1e 11.

Influence of different sizes of root cells of
TODD planter flats, seeding date and location
of transplant production on yield of Pikaed

tomato plants grown at Sodus, MI 1980.

The influence of root cell size on size of
Michigan tomato and pepper plants 1A days

after sowing.

The influence of root cell size and location
of production on the size of Pik-Red tomatoes

28 days after sowing.

The influence of root cell size and location
of production on the size of Lady Bell peppers

28 days after sowing.

The influence of root cell size and location
of production on the growth of Pik-Red
tomatoes 13 days after transplanting into the

field.

The influence of root cell size and location
of production on the growth of Lady Bell peppers

9 days after transplanting into the field.

vii

Page

AA

52

5A

55

56

Table

Table

Table

Table

Table

Table

12.

13.

IA.

15.

16.

17.

The influence
of production

20 days after

The influence
production on

20 days after

The influence
of production

47 days after

The influence
production on

HA days after

The

of transplant

influence of root cell

of root cell size and location
on the growth of Pik—Red tomatoes

transplanting into the field.

of root cell size and location of
the growth of Lady Bell peppers

transplanting into the field.

of root cell size and location
on the growth of Pik—Red tomatoes

transplanting into the field.

of root cell size and location of
the growth of Lady Bell peppers

transplanting into the field.

size and location

production on early yield of

Pik—Red tomatoe plants in 1981.

The

of transplant

influence of root cell size and location

production on the total yield

of Pik-Red tomato plants in 1981.

viii

Page

57

58

6O

61

6A

67

Table 18.

Table 19.

Table 20.

Table 21.

Table 22.

Influence of different root cell size of
TODD Planter Flats and location of trans—
plant production on the total fruit number of

Pik-Red tomato plants in 1981. 70

The influence of root cell size and location
of transplant production on the early yield

of Lady Bell pepper plants in 1981. 81

The influence of root cell size and location
of transplant production on the total yield

of Lady Bell pepper plants in 1981. 85

Influence of different root cell size of
TODD Planter Flats and location of trans—
plant production on the total fruit number

of Lady Bell pepper plants in 1981. 88

Production of ethylene (C2Hu) by Pik-Red tomato
and Lady Bell pepper seedlings grown in
Michigan and at Speedling in Florida at 1, 2

and 12 hours. 95

ix

Table

Table

Table

Table

Table

Table

23.

2A.

25.

26.

27.

28.

The level of CO2 gas produced by Pik-Red
tomato seedlings and Lady Bell pepper
seedlings grown in Michigan and at Speedling

in Florida at l and 12 hours.

The influence of cell size and spacing on the
growth of lS—day—old Pik—Red tomato seedlings

on December 8, 1981.

The influence of cell size and spacing on the
growth of 30-day-old Pik-Red tomato seedlings

on December 23, 1981.

Influence of cell size and spacing on the
growth of AS-day-old Pik-Red tomato seedlings

on January 7, 1981.

The influence of different levels of nitrogen
and phosphorus on the growth of Pik-Red

tomato seedlings 3 weeks after sowing.

The influence of different levels of nitrogen
and phosphorus on the growth of Pik-Red

tomato seedlings A weeks after sowing.

Page

96

98

99

100

118

119

Table

Table

Table

Table

Table

29.

30.

31.

32.

33.

The influence of different levels of

nitrogen and phosphorus on the growth of

Pik—Red tomato seedlings 5 weeks after sowing.

The influence of different levels of nitrogen
and phOSphorus on the growth of Pik-Red

tomato seedlings 6 weeks after sowing.

The influence of different levels of nitrogen
and phosphorus and plant age on the growth

of Pik-Red tomatoes at transplanting.

The influence of different levels of nitrogen
and phosphorus and plant age on the growth
of Pik-Red tomatoes 3 weeks after trans-

planting.

The influence of different levels of nitrogen
and phosphorus and plant age on the growth
of Pik—Red tomatoes 5 weeks after trans-

planting.

xi

Page

121

122

127

129

130

Table 3“.

Table 35.

Table 36.

The influence of different levels of nitrogen
and phosphorus and plant age on the growth
of Pik-Red tomatoes 7 weeks after trans—

planting.

The influence of different levels of nitrogen
and phosphorus and plant age on the early

yield of Pik-Red tomatoes in 1981.

The influence of different levels of nitrogen

and phosphorus and plant age on the total

yield of Pik-Red tomatoes in 1981.

xii

Page

132

133

137

Figure

Figure

Figure

Figure

Figure

LIST OF FIGURES

The influence of sowing date, location of
production, and root cell size on the early

yield of Pik-Red tomatoes in 1980.

The influence of sowing date, location of
production, and root cell size on the late

yield of Pik—Red tomatoes in 1980.

The influence of sowing date, location of
production, and root cell size on the total

yield of Pik-Red tomatoes in 1980.

The influence of root cell size and location
of transplant production on early yield of

Pik-Red tomatoes in 1981.
The influence of root cell size and location
of transplant production on the total yield

of Pik-Red tomatoes in 1981.

xiii

Page

Us—ué

A7—A8

u9_5o

65-66

68-69

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

10.

11.

12.

13.

The effect of root cell surface area on

early yield of Pik—Red tomatoes, 1981.

The effect of root cell volume on early

yield of Pik—Red tomatoes, 1981.

The effect of root cell area on total

large fruit yield of Pik-Red tomatoes, 1981.

The effect of root cell volume on total

large fruit yield of Pik-Red tomatoes, 1981.

The influence of root cell size and location
of production on the total early yield of

Lady Bell peppers in 1981.

The influence of root cell size and location
of production on the total yield of Lady

Bell peppers in 1981.

The effect of root cell area on early yield

of Lady Bell peppers, 1981.

The effect of root cell volume on early

yield of Lady Bell peppers, 1981.

xiv

Page

72-73

7U-75

77-78

79-80

82—83

86-87

89-90

Figure 1“.

Figure 15.

Figure 16.

Page
The influence of days after sowing on the
mean relative growth rate (RGR) and net
assimilation rate (NAR) on Pik-Red

tomato plants of all nutrient treatments. l2A-125

The influence of different levels of nitrogen
and phosphorus before field-setting and trans-
plant age at field—setting on the early yield

of Pik-Red tomatoes. 13A—135

The influence of different levels of nitrogen
and phosphorus before field-setting and
transplant age at field—setting on the total

yield of Pik-Red tomatoes. 138—139

XV

CHAPTER I

LITERATURE REVIEW

Introduction

 

Transplanting can be defined as the practice of
removing a plant from one place and resetting it in
another area (16). The practice of transplanting rests
upon methods developed by Old World gardeners. The acreage
of vegetables produced from transplants, the high value
of these crops, and the considerable cost of transplant
production give the ancient practice of transplanting an
important place in the economics of vegetable production (32).
The harvested acreage of green peppers in the United
States in 1981 was 56,200 acres while the acreage of fresh
market tomatoes in 1981 was 128,580 acres (5). The majority
of this acreage is planted with transplants. It can be seen
that a tremendous number of transplants are set out in the
field each year by the fresh market vegetable growers in

the United States (5“).

Advantages and Disadvantages of Transplanting

 

Using transplants in crop establishment has both
advantages and disadvantages. An important advantage of

transplanting in the greenhouse is the reduction in space

needed for plant production (32, 51). Without transplanting,
it is necessary to use a seed bed of sufficient size to
allow for growth to field transplant size without crowding
(51). Transplanting reduces the amount of expensive seed
needed to establish a good stand in the field. With certain
crops, transplanting results in earlier production, allowing
growers to take advantage of an early market. The use of
transplants also allows for production of warm season crops
in areas which normally have too short a season (32).

The main disadvantage of establishing crops by trans-
planting is the labor involved in growing the plants and
planting them in the field. However, this additional expense
may be offset by greater early yields and higher prices
received for the produce. Another disadvantage of trans—
planting is the check in growth to the young plants which
occurs as a result of disturbing and resetting the root
system (51). Depending on many factors, this check in
growth may be easily offset by an increase in root branching
in crops such as tomatoes, cabbage, lettuce and beets. In
other crops such as corn, beans, melons and cucumbers, the
check in growth may be severe due to limited root replacement

(32).

Problems Encountered During Transplant Production
Several problems are commonly reported by growers setting
transplants into the field. The use of poor quality trans-

plants may cause the spread of disease. A large number of

tomato transplants are produced in southern Georgia and
shipped to the North each year (39). Because these trans-
plants may reach the size suitable for certification in the
South when weather conditions are unfavorable in the North,
growers are often forced to store transplants. The
infection of tomato seedlings by fungal and bacterial
diseases increases as the storage period is lengthened

(22, 50). Because of this problem, and damage incurred
during shipment, some northern growers are reluctant to use
southern—grown transplants (39).

Root binding will occur if a plant is stored or grown
in a container for an extended period. Root binding is
characterized by an inability of the growing root system to
expand. This results in a stunted transplant which can
exhibit a serious check in growth after transplanting (59).

An important problem affecting the growth of trans-
planted crops is transplant shock caused by disturbing or
resetting a plant's root system. Transplant shock after
field-s tting is marked by sudden wilting, a decreased rate
of new root formation and an overall check in the growth of
the plant. In an elaborate set of experiments carried out
at Ithaca, New York with several types of vegetables,
Loomis found that transplanting always resulted in a check
in growth. The check in growth of the transplants was
found to be proportional to the size of the plant at the

time of transplanting. Large plants were more seriously

injured than small transplants in his study because the

proportion of retained roots was smaller for the larger

transplants. Loomis states:
those plants having root systems of such a form as
to be largely lost in transplanting or whose older
roots are heavily suberized so they must depend upon
the outer portions of the root system for their
moisture supply, will be more seriously injured than
plants having a more branched and less heavily
suberized root system (32).

Loomis suggests that the root system plays a critical
role in transplant recovery. The three most important
factors which influence this recovery are: l) the
proportion of the root system retained after transplanting,
2) the capability of the retained roots to absorb water
after transplanting, and 3) the rate of new root formation.
He found that the immediate effect of transplanting was a
reduction in the available water supply to the transplant
(32).

The rate of new root formation, which influences water
uptake, may be the most significant factor in the reestab-
lishment of transplanted vegetable crops. A correlation
was shown to exist between the ease of transplanting and
the rate of new root formation. Vegetable species which
are easily transplanted exhibit a.fastrate of root replace-
ment as well as a fast rate of top growth. Plants which
are seriously injured by transplanting usually exhibit a
slow rate of root replacement but a rapid rate of top

growth. The rate of root replacement decreased with

increasing age of the vegetable transplant (32). Thompson

and Kelly believed that all factors which affected trans—
plant recovery eventually act by influencing the water

supply of the transplant (51).

Cultural Practices Used in Transplant Production

 

Many different types of transplants are used by fresh
market tomato and pepper growers. In the past, growers
have used field-grown transplants produced in the
Southern United States and shipped north in the spring.
Over 700 million tomato transplants are produced in southern
Georgia for northern growers each year (39). These southern
transplants are grown in the field at close spacing in
seedbeds. Often these bare—rooted transplants are not of
the quality desired by northern growers. Bare-rooted
transplants often lose a considerable portion of their root
system upon removal from seedling beds. Observable set-
backs in vegetative growth often occur (A9). Water and
nutritional stress caused by root damage also result in
transplant shock (32, A9). Early yields are often reduced
due to extensive root damage occurring during removal from
seedling beds (12, 3A, A9). Diseases caused by production
in contaminated seedbeds and prolonged periods of storage
before shipment also reduce plant stand and yields (22, 50).

Field-grown transplants are cheaper to produce than
other transplant types because less labor and energy are

required for field production than for intensive greenhouse

6

production. However, a warm climate is necessary for
early production of the field-grown transplants used by
northern growers. Soil for field-grown transplants should
be fertile, friable, well-drained and free from insect and
disease infestation (5A).

Growers also use transplants produced in greenhouses
for crop establishment. These transplants may be produced
in containers or direct-seeded into soil beds in the green-
house. Greenhouse-grown transplants are often of higher
quality than field-grown transplants because the grower
maintains control over environmental factors influencing
plant growth. However, these transplants are more
expensive to produce because of increased energy and labor
requirements during their production (5A).

The selection of a growth medium for transplant pro-
duction is an important decision to be made by the trans—
plant producer. An ideal container mix is achieved by
combining coarse textured amendments with fine-textured
materials. This allows for the formation of many pores
for adequate water storage (A7). To avoid water stress
after transplanting, caused by decreased water retention
of certain soil mixes, the grower should irrigate frequently,
shade or protect the plants from excessive drying and use
a soil mix that contains a sufficient number of small
pores (A8).

Plants grown in the greenhouse may be started in a

seedbed and later transplanted to cells, flats or beds or

direct-seeded into containers for growth until field setting.
Seeds are sown thickly into a seedbed for transplanting
into the greenhouse. When the first true leaves are well
developed the seedlings are thinned or transplanted into
cells, flats, benches or beds. The taproot is usually
broken and many feeder roots are broken off in removing

the transplant from a seedbed. This results in increased
root branching. Depending on the plant species and size of
the transplant, increased root branching may result in an
increased absorptive capacity. However, if the roots are
seriously disturbed and the soil around the roots does not
remain intact, a check in growth may occur (51).

Teubner (A9) demonstrated that transplanting bare-
root plants or plants with a minimum of soil adhering to
the roots resulted in noticeable setbacks in vegetative
growth of tomato plants. The adverse effects of trans-
planting shock on the development of the young flower buds
was less apparent but potentially more serious since early
yields declined. He attributed the abortion of developing
flower buds to the diversion of food reserves to the
injured root system along with decreased moisture and
nutrient levels as a result of root damage (A9).

Wooden flats are commonly used in the greenhouse to
propagate fresh market tomato and pepper transplants. Flats
are easily used, but are not necessarily the best container
to use to produce high quality transplants. Researchers

have found that flat—grown transplants produce lower early

yields than other container types (3A, A9). Transplanting
from a flat results in either bare-root transplants or
those with a minimum of soil surrounding the root system
(A9). Transplanting shock created by this root damage
often results in water and nutritional stress, flower
abortion, setbacks in vegetative growth and decreased early
yields (32, 3A, A9).

Other types of transplant containers frequently used
by vegetable producers include veneer bands, paper bands,
clay, peat and plastic pots. Ball (8), Campbell (11) and
Nylund (38) have shown that tomato transplants grown in
peat, clay or plastic pots produced larger early yields
than those grown in flats or paper bands. Nylund also
reported that pot—grown tomato transplants produced 117%
greater early yields and 16% greater total yields than flat-
grown transplants (38). The differences in yield were
probably due to decreased root damage during transplanting
when pots are used (3A). Thompson and Kelly agree that the
main advantage in using pots is that the roots are not
disturbed when the plant is set in the field (51).

Peat pots are formed from compressed peat material.
They remain around plant roots at transplanting thereby
minimizing disturbances to the root system. Plastic or clay
pots involve additional labor in picking up, washing and
storing the containers after transplanting. These pots
can be re-used for several years if they are sterilized

after each use. Paper and veneer bands are lightweight,

9
inexpensive containers which are not re-usable. They are
not particularly sturdy, but are easily stored. Most
container types are available in a variety of sizes to meet
the needs of vegetable producers (3A).

TODD planter flats, produced by Speedling Inc. in Sun
City, Florida, are becoming popular as containers for
greenhouse-grown vegetable transplants. The flats are made
of expandable polystyrene and can be re-used many times.
They come in a number of root cell sizes, with a descriptive
number indicating the cell size; e.g., a 100 size flat has
cells 1 inch across, a 125 size flat has cells 1.25 inches
across. The cells are square, inverted pyramids. Speedling
claims that the unique inverted pyramid design encourages
downward root growth and allows natural air pruning, while
minimizing root-binding problems and virtually eliminating
transplant shock. Speedling transplants produced in the
TODD planter flats are reported to have a 95%-p1us
survival rate (3).

The most common size of the TODD planter flat measures
68 cm in length by 3A cm wide. The depth of the flat
varies from 2.5 to 10 cm. The cell sizes range from 2 cm
to 5 cm square. The number of cells varies from 18 for
the 200 size flats to 288 for the 080 flats, creating
transplants of many sizes to meet the needs of vegetable
and bedding plant producers (A).

Speedling recommends using a Cornell Peatlite growing

mediumin the TODD planter flats. This growing medium

10

consists of peat and vermiculite with a special fertilizer
formulation added. The mix provides elasticity, drainage
and nutrient exchange capacity to produce transplants

that are virtually disease-free (AA). Speedlings' ultimate
goal is to produce healthy, stocky vegetable seedlings

with good green color in approximately A to 5 weeks from
direct seeding (A).

Speedling tomato and pepper plants are shipped to
many parts of the United States, including Michigan.
Speedling also markets its TODD planter flats for use by
growers in their own greenhouses (2).

Obtaining high quality transplants is one of the most
important factors in fresh market tomato and pepper
production (13, 2A, 25). Transplant quality affects stand
establishment, early yield, total yield and fruit size
(25, 37). In the case of tomatoes and peppers, a stocky
young plant free from insect and disease infestation and
possessing neither open flowers nor buds is desired (35,
5A).

Early production is usually desired because of the
short growing season in the North and the high value of the
crop during the first 2 weeks of the marketing season
(12, 38). Several cultural practices are known to affect
eearly yields of tomatoes and peppers. These include the
rnethod of transplant production, the use of starter

Sc>lution, fertilization program, the spacing of plants in

CC>ntainers prior to field-setting, the size of the

11

transplant container, and the age of the seedling at trans-
planting (12, l3, 38). Nicklow and Minges suggest that
tailoring cultural practices to a tomato variety may be
very important to realize maximum yielding potential (37).
Many researchers have shown that earlier tomato yields
in the field are directly correlated with space per plant
in the greenhouse (12, 25, 37, A2). Nicklow and Minges
found that greater space per plant resulted in more leaves
at the first cluster, a stockier plant, and faster overall
growth which resulted in earlier flowering and greater
early yield (37). Other researchers have shown that
tomatoes grown in 3 inch pots produced greater early yields
than flat—grown plants (8, 11, 38, 55). Lamm (26) and
Knavel (2A) reported that tomato plants grown in A inch
pots produced greater early yields than plants grown in
2 l/A and 3 inch pots. Romshe (A0) demonstrated an increase
in both early and total yields of tomatoes grown in plant
bands with an increase in the size of the plant bands.
He found no differences in yields of tomatoes grown in
wood veneer, Manila paper or heavy asphalt paper bands
(A0). Sayre noted that giving tomato plants 25% more space
in the flat by setting out fewer seedlings per flat
resulted in earlier yields in the field. However, growing
the plants in deeper flats containing 33% more soil did
not increase the yields during two growing seasons (A2).

Kretchman and Short reported that tomato transplants grown

12

in 2-inch TODD planter cells produced slightly larger
yields from a single harvest than did transplants grown
in l-inch cells (25).

Several researchers have offered explanations for
the increase in early yield of tomatoes with an increase
in container space. Casseres believed that young tomato
roots from wider spacings were only slightly disturbed at
field setting, allowing for resumption of vegetative
growth. Plants grown at a closer spacing suffered more
damage to their root systems at transplanting and were
set-back (12). Nicklow and Minges questioned this
explanation. They believed that the wider spacing influenced
the physiological condition of the transplant before field
setting (37). Knavel reported that tomato plants reach a
nutrient starvation stage more quickly when grown in small
containers, while larger containers hold enough fertile
soil mix to support adequate root development until field
setting. Knavel also noted that the spacing of pots on
greenhouse benches influenced the early yields of tomato
fruit. Greater early yields were obtained from plants
grown at an 8 by 8 inch spacing between containers than
from plants grown at a A by A inch spacing. This was true
for plants in containers of various volumes and materials
(2A).

The age of transplant, or stage of physiological

maturity, affects plant growth and subsequent yields after

l3

transplanting. Nicklow and Minges reported that a

relatively small 3-to 5-week-old tomato transplant with-

out flowers or buds produced the largest fruit and the
largest total yields. Larger plants with visible flower

buds produced earlier yields. Old plants which were over-
hardened or were in flower were never desirable (37).
Casseres and Sayre also found that younger tomato transplants
produced larger yields than older transplants (12, A2).
Casseres reported that 6-week-old tomato transplants which
were tender and capable of quick recovery after transplanting
produced greater early and total yield than lO—and lA-week-
old plants (12). Sayre found that 7—week-old transplants
produced greater early yields than did 9-and ll-week-old
transplants (A2).

In an experiment repeated over 3 years, Skapski and
Lipinski demonstrated that very young and small tomato
seedlings 3 to A weeks old can be transplanted successfully
only in good growing seasons in Poland. These 3-to A-week-
old seedlings produced lower total yields than did trans-
plants 6 to 8 weeks old. Root and shoot growth of 3—to A-
week-old transplants were retarded while older transplants
were not seriously affected by adverse weather conditions
(A5). Babb reported that increased tomato root growth after
transplanting was associated with a young state of maturity
of the plant, rather than the initial size of the transplant
(7).

lA

Transplant Nutrition

 

It is important to provide tomato transplants with
an adequate level of essential nutrients before and after
field setting to allow for quick transplant recovery and
growth. Otherwise, nutrient deficiency symptoms often
appear when seedlings are transplanted into cool spring
soils (53, 57). The limited root system of the trans-
plants may also contribute to the development of a nutrient
shortage (57).

Phosphorus is a major nutrient that plays an important
role in seedling growth and development. It is known to
stimulate root production, promote rapid growth in
seedlings and is necessary for cellular metabolism (5A).

Tomato plants have a high phosphorus requirement early
in the season when root systems are small and temperatures
are cool (36, 52, 56, 57). Murphy (36) and Jones and
Warren (23) have found that early phosphorus uptake is
more important in influencing early yield of tomatoes than
total phosphorus uptake. Several researchers have shown that
greater early phosphorus uptake results in more rapid
growth of tomato seedlings and an increase in early tomato
fruit yields (7, 36, Al, 56, 57).

Tiessen and Carolus found that tomato root develop-
ment benefited greatly from high levels of phosphorus and
nitrogen in the fertilizer solution (52, 53). Tomato

root regeneration was very active the first 3 days after

l5

transplanting. Phosphorus was necessary to meet this
requirement and unless phosphorus was supplied in the
starter fertilizer, soluble phosphorus in the plant tissue
remained at low levels, even with adequate nitrogen
supplies. A lack of growth resulted in an accumulation

of soluble nitrogen (53). Wilcox reported that the
phosphorus requirement for optimum root growth of tomato
seedlings can be satisfied by placing a small amount of
phosphorus fertilizer in close proximity to the root system
so that the concentration of phosphorus in the soil solution
near the roots increases (56).

Nitrogen is also a major nutrient that strongly affects
seedling growth rate. It is known to promote rapid
vegetative growth and green color, and is essential in the
formation of proteins and other compounds in the tomato
(33).

The level of nitrogen in the soil can significantly
affect the growth of transplanted tomatoes. Wilcox and
Langston reported that nitrogen was the primary limiting
element to tomato seedling growth in an experiment using
a soluble nutrient solution. They found that direct
seeded tomatoes responded more to additional phosphorus
than did transplants, but transplanted tomatoes responded
more to additional nitrogen (57). Jaworski reported that
although phosphorus is the major element limiting high

tomato transplant yields in the fields of Georgia, a

l6

moderate level of nitrogen was necessary to produce large
marketable yields and uniform development of transplanted
tomatoes (l9). Tiessen and Carolus found that early

root growth was depressed when nitrogen was absent from
the nutrient solution. This indicated that nitrogen was
necessary for root regeneration also (A9).

The availability of nitrogen is an important factor
in the propagation of tomato plants. High fertilization
with nitrogen may cause a build-up of soluble salts in
the soil, causing a reduction in plant stand. Over-
fertilization may cause seedlings to become too succulent,
resulting in susceptibility to disease and physical
damage. However, low fertilization with nitrogen may
result in small transplants of poor quality. The source
of nitrogen in a fertilizer influences its availability
(20).

The balance of nitrogen to phosphorus in transplants
may be a very important factor influencing plant growth
and yielding ability in northern production areas.
Jaworski and Webb found that fruit yields were affected by
the nitrogen/phosphorus balance. The highest yields
were obtained with either low levels of both nitrogen and
phosphorus or high levels of both nitrogen and phosphorus.
High nitrogen, in the absence of sufficient phosphorus,
caused a significant yield reduction (21). Wittwer and

Honma recommended applying 30 ppm phosphorus and 200 ppm

17
nitrogen weekly in nutrient solution to seedling tomatoes
grown in the greenhouse in artificial media (58).

Potassium is a major element which plays a lesser
role in tomato transplant nutrition. High levels of
potassium were shown to have little effect on the growth
of tomato transplants either in the field or greenhouse
(53, 57). Tiessen and Carolus found that initially,
tomato root development benefited more from nitrogen and
phosphorus in the nutrient solution than from potassium
(52). Murphy reported that phosphorus produced a greater
response than potassium when working with southern-grown
transplants on newly cleared land (36). Jaworski also
found that high potassium levels did not affect the market-
able yield of transplanted tomatoes (19). Tiessen and
Carolus believed that potassium is seldom limiting to
the transplant (53).

Vegetable plants often benefit from applications of
starter solutions containing soluble fertilizers at
transplanting (Al, A2, 52, 51). The use of a starter
solution enabled transplanted tomatoes to become estab-
lished more quickly. This resulted in a significant gain
in early maturity (Al). Transplanting shock was reduced
when transplants received high analysis fertilizer in
solution. Tiessen and Carolus reported that starter
solutions formulated for tomatoes should contain higher

phosphorus and perhaps nitrogen and lower potassium levels

18

to promote initial root regeneration and high percentage
survival (52). Sayre found that nutrient solutions
containing nitrogen, phosphorus and potassium were more
effective than solutions which lacked any of these

nutrients (Al).

Growth of Tomato and Pepper Plants

 

Tomatoes and peppers both belong to the family
Solanaceae. However, the growth pattern of these plants is
different. The pepper shoot first forms a single stem
which branches into two. One or more flower buds are
produced at the point of diversion. After the production
of a few more leaves, each branch divides again. Second
layer flower buds develop at each point of diversion.
Growth than continues in this manner (A6).

The pepper root system first forms a primary root
which grows downward. By 2 months of age, the root system
is well-branched with. laterals extending 10 inches on
either side of the 10 inch primary root. The tap root is
often damaged after transplanting and horizontal and
lateral roots constitute an important part of the absorption
system. At maturity, most of the root system is located
in the top 2A inches of soil (1A).

Aung has reported that tomatoes follow a sympodial
growth pattern, where the main axis of growth terminates
in an inflorescence and successive growth starts from a

lateral shoot in the axil of the last initiated leaf.

19

The axillary shoot below the first inflorescence usually
exhibited greater vigor and fruiting ability than any
other axillary shoot on the main stem (6). Leonard and
Head found that stem length of tomatoes increased
uniformly throughout the growth period. Leaf number on
the main stem increased steadily until fruit ripening,
when a decrease in leaf number occurred (27).

Leonard and Head (27) noted that the tomato plant
first develops a primary root. Phase I consisted of a
short period of exponential growth of the root. At the
same time, exponential growth of the stem occurred and
flowers opened. Phase II was marked by a high growth rate
of all organs. Phase III showed a drastic decline in the
number and amount of roots as the first fruits formed on
the plant. An increase in root growth was noted in phase
IV as the first fruits were harvested. In phase V root
number and length remained constant.

J. P. Hudson (18) reported that the tomato:

must make continuous and rapid vegetative growth through-
out the season if it is to remain in production, although
a careful balance must be maintained between vegetative
and fruiting activities, if the plant is to produce a
heavy yield of the right type of fruit, at the right
time.

He believed that the root/shoot ratio played an important

role in maintaining this balance. Leonard and Head (27)

found that the growth of tomato roots was closely related

to the rate of new fruit production (27). Hudson's work

suggested that the tomato fruit was able to monopolize

20

the food resources of the plant at the expense of other
organs, including the roots (18).

The growth of tomatoes and peppers includes an early
exponential phase when growth is potentially unlimited.
The embryo of a plant will begin to grow exponentially and
photosynthetic efficiency will determine the rate of
growth. Growth may be defined as an increase in fresh
weight or an accumulation of dry weight (28).

Interactions with the environment and within an
individual soon impose limitations on growth and the actual
growth curve becomes sigmoidal. The transplant's growth
rate is significantly affected by variations in exposure
to such environmental factors as light, temperature,

carbon dioxide level, water supply and nutrition (28).

Summary

Obtaining high quality transplants is one of the most
important factors in fresh market tomato and pepper pro-
duction (13, 2A, 35). The best quality plants are young,
stocky, free from insect and disease infestation, and have
no open flowers or buds (35, 5A). Transplant quality
affects stand establishment, early yield, total yield and
fruit size (25, 37). The use of certain cultural practices
significantly affects tomato and pepper transplant quality.
Tailoring cultural practices to tomato and pepper trans-
plants may be very important in realizing maximum yielding

potential (37).

21

Past research has determined that variations in
transplant type, container size, transplant spacing,
fertilization program and transplant age significantly
affect tomato and pepper transplant quality. Transplants
produced in large individual containers produce larger
early and total yields than bare-root transplants or those
produced in smaller individual containers (8, 11, 2A, 25,
26, 38, A0, A2, 55). Increased spacing between transplant
containers in the greenhouse produced increased yields
over closely spaced transplants (12, 25, 37, A2). Tomato
transplants required large amounts of phosphorus to
promote root growth and large early yields (7, 35, Al, 56,
57). Moderate levels of nitrogen were also necessary to
produce large early and total yields (17, 19, 33, 57).
Tomato fruit yields were affected by the ratio of nitrogen
to phosphorus applied to the transplants (21). In general,
tomato transplants of A to 7 weeks of age produced larger
early and total yields than either older or younger
transplants (12, 37, A2, A5).

The purpose of this research was to examine the
Speedling system of transplant production using TODD
planter flats. This system may prove to be an alternative
to the use of bare—rooted Southern transplants for fresh
market tomato and pepper production in Michigan. The
growth and productivity of these different transplant

types were compared. The location of transplant production

22

was studied to determine if high quality TODD transplants
could be produced in Michigan or at Speedling of Florida.
Cultural practices also play a critical role in determining
the quality of tomato and pepper transplants. Various
cultural practices were examined in an effort to decrease
transplant shock and increase the growth and yield of
Pik-Red tomatoes and Lady Bell peppers. The cultural
practices studied with respect to their effect on growth,
development and yielding ability were: different root cell
sizes of TODD planter flats, different transplant spacings
within TODD planter flats, various rates of nitrogen and
phosphorus fertilization, and different ages of transplants
at field-setting. A high quality transplant, exhibiting
little if any transplant shock and producing large early

and total yields, was desired.

CHAPTER II
A COMPARISON OF THE EARLY GROWTHlflfliYIELD OF TOMATO

AND PEPPER TRANSPLANTS PRODUCED IN THREE DIFFERENT
GROWING CONTAINERS

Introduction

 

Wooden flats are often used to propagate fresh market

tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum

 

annuum L.) transplants in the greenhouse. However, flats
are not necessarily the best container to use to produce
high quality transplants. Researchers have found that
peat, clay or plastic pots produce stockier vegetable
transplants and larger early yields than flats or paper
bands (3A, A9). The differences observed in early yield
are usually due to less root damage occurring during trans—
planting from pots (3A). Transplanting shock created by
root damage causes water and nutritional stress (32, A9).
Abortion of the developing flower buds may result (A9).
Several new types of transplant containers are gaining
popularity with U.S. growers. The Jiffy-7 pellet is an
expandable peat container filled with artificial soil mix
and fertilizer. F. G. Teubner recommends placing the
entire peat container in the ground at transplanting
allowing the root system to remain intact and minimizing

transplanting shock (A9).

23

2A

The Speedling system is also reported to produce a
high quality transplant with a low mortality rate. The
Speedling transplants are grown inpcdystyrene TODD planter
flats containing individual root cells filled with peat—
lite soil mix. Each cell is designed as an inverted
pyramid to encourage downward root growth and natural
air pruning at the open bottom. The tapered root system
releases easily from the flat and can be transplanted with
minimal root shock according to Speedling. The planter
flats are available in several different sizes of root
cells (3).

The purpose of this experiment was to compare the
early growth and yield of tomato and pepper transplants
produced in standard wooden flats, Jiffy-7 pellets and
Speedling root cells of size 125. It was of particular
interest to determine if it is feasible to use the
Speedling system in Michigan as an alternative to bare-

rooted or flat-grown transplants.

Materials and Methods

 

On August 21, 1980, 80 Pik—Red tomato seeds were sown
into each of the following: a standard wooden flat
measuring 1A by 20 inches, 80 Jiffy-7 pellets and 80
Speedling 125 root cells in one planter flat. The area of
each Speedling root cell was 10.1 sq. cm. A peatlite

soil mix was used in the flats. In the second experiment,

25
Lady Bell pepper seeds were also planted in a similar
manner in a wooden flat, Jiffy-7 pellets and a Speedling
125 planter flat. The plants were grown on benches in
the greenhouse.
The seedlings were watered when necessary and ferti-
lized weekly with a soluble 20—20-20 fertilizer at a

rate of 3.9 ml fertilizer per liter H 0 after the first two

2
leaves appeared. On September 21, 1980, 20 seedlings
were harvested at random from each treatment of the tomato
and pepper experiments and measured for height, leaf
number, stem diameter and shoot and root fresh weight to
give an indication of seedling size at transplanting.
Root fresh weight was obtained by washing and weighing
the roots of each seedling, while stem diameter was
measured with a vernier calliper. Each plant was considered
a replication. Results were analrzed by analysis of
variance and means separated by Duncan's multiple range
test, 5% level.

Of the remaining seedlings, 8 tomato and pepper
plants of each treatment were selected at random and
transplanted into 25.A cm pots containing a plastic liner
filled with sterile soil. The transplants were fertilized
with a soluble 20—20-20 fertilizer at a rate of 3.9 ml

fertilizer per liter H O at transplanting and each week

2

thereafter. The pots were arranged in a completely

randomized design with each plant considered a replication.

26

One greenhouse bench under fluorescent lighting was used
for each experiment. On January 8, 1981, the plants
were harvested in a once—over harvest and the number of
fruit and fresh weight of the fruit of each plant were
recorded.

Results were analyzed by analysis of variance and

means separated by Duncan's multiple range test, 5% level.

Results

Stem diameter, shoot fresh weight and leaf number of
Jiffy-7 tomato and pepper seedlings before transplanting
were significantly greater at A weeks of age than those
of flat-grown or Speedling 125 plants (Tables 1 and 2).
fflmaheightsof Jiffy-7 plants and flat-grown plants were
not significantly different. Speedling 125 tomato and
pepper plants were shorter, had fewer leaves and smaller
stem diameter, shoot weight and root weight than plants
of the other treatments. In general, after A weeks of
growth, Jiffy-7s produced the largest, stockiest trans-
plants while the Speedling 125 root cells produced the
smallest transplants for both tomatoes and peppers.
Root systems of the Jiffy—7 plants were extensive and light
yellow in color, while those of the Speedling and flat-
grown plants were white at transplanting.

There was no difference in the fresh weight of tomato

and pepper fruit for Speedling 125, Jiffy-7 and flat-grown

27

plants (Tables 3 and A). However, it was noted that Speed-
ling 125 tomato and pepper plants produced more fruit with
a greater percentage of red color than did any of the other

treatments.

Table 1. Influence of containers on the size of Pik-Red
tomato seedlings grown at Michigan State University
at A weeks of age.

 

z z
Plant z Stem z z
height Leaf diameter Shoot fresh Root fresh
Treatment (cm) number (mm) weight (g) weight (g)
Flat 25.1b A.2a 3.8b 3.0b 0.9b
Jiffy-7 2A.2b A.8b A.lc 3.8c 0.9b
Speedling
125 16.7a A.0a 2.8a 1.1a 0.5a

 

ZMeasurements are the means of 20 plants, harvested on
September 21, 1980.

Mean separation in columns by Duncan's multiple range test,
5% level.

Table 2. Influence of containers on the size of Lady Bell
pepper seedlings grown at Michigan State University
at A weeks of age.

 

z z
Plant 2 Stem z a
height Leaf diameter Shoot fresh Root fresh“
Treatment (cm) number (mm) weight (g) weight (g)
Flat 15.3b 5.3a 2.8b 1.3b 0.2a
Jiffy-7 16.6b 6.7b 3.00 2.30 O.6b
Speedling .
125 11.0a A.7a 2.0a 0.6a 0.3a

 

2Measurements are the means of 20 plants, harvested on
September 21, 1980.

Mean separation in columns by Duncan's multiple range
test, 5% level.

Table 3.

28

Influence of containers on the yield of Pik—Red
tomato transplants grown at Michigan State
University.

 

Fruitz Fruitz
Treatment number weight (g)
Flat 8.6a 706.8a
Jiffy-7 8.8a 769.3a
Speedling 125 9.0a 778.9a

 

2
Measurements are the means of 8 plants, harvested on January

8, 1981.

Mean separation in columns by Duncan's multiple range test,

5% level.

Table A.

Influence of containers on the yield of Lady Bell
pepper transplants grown at Michigan State Univer—
sity.

 

FruitZ Fruitz
Treatment number weight (g)
Flat 6.3a 215.5a
Jiffy-7 5.8a 28A.Aa
Speedling 125 5.2a 198.1a

 

ZMeasurements are the means of 8 plants, harvested on January

8, 1981.

Mean separation in columns by Duncan's multiple range test,

5% level.

Discussion and Conclusions

 

Speedling 125 tomato and pepper plants were signifi-

cantly smaller than Jiffy-7 or flat-grown transplants on

September 21, 1980. The size of Jiffy-7 and flat-grown

plants was similar. The smaller size of the Speedling 125

29

plants may have been due to their smaller root cell volume
than that of the Jiffy—7 or flat—grown plants. Vegetable
transplants grown in larger individual containers of flat
spacings produced more leaves at the first cluster, a
stockier plant and a faster overall growth rate (37).
Nicklow and Minges believed that the larger spacings or
container sizes influenced the physiological condition of
the transplant before field setting (37). The reduced
space available to the Speedling transplants relative to
the Jiffy—7 and flat—grown transplants apparently resulted
in slower growth rates and thus smaller plants at the time
of transplanting.

There were no visible differences in the size of the
plants of any treatment at fruit harvest. There were no
significant differences between treatments in either fruit
number or yield. However, it was noted that Speedling 125
tomato and pepper plants produced more fruit with a greater
percentage of red color than did either of the other
transplant types. This may be an indication that the
Speedling 125 plants matured faster than either of the
other transplant types.

Speedling 125 plants did not appear to be root-bound
and retained all of the root system at the time of trans-
planting. However, the Jiffy-7 plants appeared to be
root-bound, judging from the compacted, yellow appearance

of the root system, while the flat-grown plants lost a

30

significant portion of their root systems at transplanting.
As a result, the Jiffy-7 and flat-grown plants were more
likely to suffer water stress after transplanting. Although
the Speedling 125 seedlings were smaller at transplanting,
they apparently were able to catch up with the other plants
after transplanting due to an actively growing root system.
Speedling, Inc. states that transplants produced in TODD
planter flats exhibit minimal transplanting shock and a
rapid growth rate after transplanting (3, A). The data from
this experiment seem to support this statement.

Several researchers have found that transplants grown
in larger individual containers or spacings in a flat were
larger at transplanting and produced higher early yields
than those grown in smaller containers (12, 2A, 25, 26,

32, 37, A0, A2), but the results of this experiment indicated
that the total yield from a once-over harvest may be in-
dependent of plant size at transplanting. Therefore, we
decided to compare the development and yield over the

course of the picking season of transplants grown in
different TODD root cell sizes and transplanted into the

field.

CHAPTER III

STUDIES ON THE EFFECT OF ROOT CELL SIZE, PLANT
SPACING AND LOCATION OF PRODUCTION ON
DEVELOPMENT AND YIELD OF TOMATO
AND PEPPER TRANSPLANTS

Introduction

 

A preliminary experiment comparing the growth and
yielding ability of Speedling 125, Jiffy—7 and flat-grown
tomato and pepper transplants showed that Speedling trans-
plants are a possible alternative to bare-rooted plants.
The Speedling plants, however, exhibit a lag phase after
transplanting before reestablishing a normal growth rate.
This is a distinct disadvantage because tomato and pepper
plants must make continuous and rapid vegetative growth
throughout the season and balance vegetative and fruiting
activities. The root/shoot ratio plays an important role
in maintaining this balance (18). Speedling plants with .
larger size root balls appear to establish a rapid growth
rate more quickly than plants of the same age with
smaller root balls both before and after transplanting.

Numerous researchers have found that transplants
grown in larger individual containers were larger at the
time of transplanting and produced larger early yields

than did plants grown in smaller containers (8, 12, 2A, A0,

31

32

51). Increased container depth had less effect than
increased container area on early yielding ability of tomato
transplants (A2). Therefore, the area and volume of the
root cell container in the TODD planter flat may influence
the growth and yielding ability of tomato and pepper trans-
plants.

The spacing between plants while in greenhouse flats
may also affect the growth of vegetable seedlings. Trans-
plants grown at wider flat or bench spacings are larger and
stockier at the time of transplanting, and maintain a
faster growth rate which results in earlier flowering and
greater early yield (12, 2A, 37). Seedlings grown in larger
TODD root cell sizes naturally have wider plant spacings
since the sides of each root cell are larger.

The location of transplant production and subsequent
shipment of transplants may also play a role in influencing
the growth and early yield of tomatoes and peppers. Plants
produced in Sun City, Florida may be adversely affected
by cultural or shipping practices followed by Speedling,
Inc. Increased levels of ethylene and CO2 gas are
produced as a result of any stress experienced in ship—
ment. Ethylene production increases rapidly following
trauma cuased by drought, temperature extremes and
mechanical wounding (1). Ethylene produced in this manner
is known as stress ethylene. Stress ethylene may play a

role in senescence of the plant tissues. Increased levels

33

of ethylene produced by Speedling transplants during
shipment may detrimentally affect the growth of the trans-
plant seedlings in the field.

These studies were undertaken to compare the growth
and yield of tomato and pepper plants produced in different
root cell sizes and grown in Florida at Speedling, Inc., and at

Michigan State University.

Materials and Methods

 

A. The Effect of Root Cell Size and Production Location on
Yield of Pik-Red Tomato Transplants in 1980.

 

 

This experiment was conducted at the Sodus Research
Station in Sodus, Michigan in 1980. The Sodus area is the
main growing region for fresh market tomatoes in Michigan.

Four-week-old Pik—Red tomato plants of root cell sizes
080, 100A and 125 produced by Speedling Inc. in Florida were
shipped to Sodus, Aichigan by truck. Pik-Red tomatoes of
the same seed lot were also grown in the greenhouse at
Sodus, Michigan in TODD flats of 080, 100A, 125, 150 and
175 root cell sizes. Two plantings were made at Sodus,
Michigan, resulting in plants of A and 6 weeks of age at
transplanting.

Speedling plants were sown on May 13, 1980. Michigan
plants were sown on April 30 and May 13, 1980. Seeds for
Michigan-grown plants were pregerminated for A8 hours and

suspended in Viterra-II gel before sowing. All plants were

transplanted into the field on June 11, 1980. The roots

3A

of the transplants were dipped in soluble 20—20—20 starter
fertilizer solution before field setting. The plants
were irrigated overhead after transplanting.

Nitrogen was broadcast on the rye cover crop in the
field at a rate of 56 kg/ha and plowed down in the spring.
56 kg/ha N and 169 kg/ha K20 were broadcast and disced in

before planting and the plants were sidedressed with N at

a rate of 28 kg/ha after fruit set. No P was added since

205
soil test levels were over 337 kg/ha. Overhead irrigation
was used when necessary. Fungicides, insecticides and
bactericides were applied where necessary to control

foliar diseases.

The experiment was designed as a randomized complete
block with 3 replications. Six plants were transplanted per
plot, with 2 feet between plants and A feet between rows.
Data collected included the number of live plants and yield
per plot. The tomatoes were harvested weekly. Weight of
fruit per plot was recorded at each harvest. The first
harvest was on August 1A, 1980 and harvesting continued
until September 17, 1980. Yields of the first 2 weeks
were considered as early yield. Yields from the third and
fourth weeks were considered as midseason yield, and yields
from the fifth and sixth weeks were late yield.

Results were analyzed by analysis of variance and

means separated by Duncan's multiple range test, 5% level.

35

B. The Effect of Root Cell Size and Production Location
on Development and Yield of Pik—Red Tomato and Lady
Bell Pepper TransplantsJ 1981.

 

 

 

This experiment was conducted at the Horticulture
Research Farm and Plant Science Greenhouses of Michigan
State University, East Lansing, Michigan, in 1981.

Pik-Red tomato and Lady Bell pepper seeds were pre-
germinated for A8 and 72 hours, respectively, and suspended
in Viterra II hydrogel for sowing at Michigan State
University. One hundred fifty seeds of each crop were sown
into each of 6 cell sizes (080, 080A, 100A, 125, 150, 175)
of TODD planter flats on May A, 1981. The flats were
filled with a peatlite soilless mix. As soon as the first
true leaves appeared, the plants were fertilized weekly
with a soluble 20-20-20 fertilizer at a rate of 3.9 ml
fertilizer per liter of H20. Transplants were hardened in
a lathi house at Michigan State University for 3 days
before planting in the field.

Pik-Red tomato and Lady Bell pepper seeds of the same
lots used at MSU were planted on May A, 1981 in TODD
planter flats of the same 6 cell sizes at Speedling Inc.
in Sun City, Florida. Plants were shipped by air freight
to Lansing, Michigan on May 27, 1981 in cardboard boxes
equipped with air holes for ventilation.

Height, leaf area and shoot dry weight of A randomly
selected plants from each treatment were measured for

Michigan-grown tomato and pepper seedlings at the first

36

true leaf stages. Leaf area was measured using an elec—
tronic leaf area meter with digital read-out, while dry
weight was measured with a Mettler balance. Height of
each plant was measured individually; leaf area and dry
weight were pooled for the A plants of each treatment.
Upon arrival in Michigan, the Speedling plants were
measured in the same manner. Results were analyzed by
analysis of variance and means separated by Duncan's
multiple range test, 5% level.

The tomatoes were planted in the field May 28, 1981.
The peppers were planted May 29, 1981. Weather conditions
were ideal for good establishment and growth. Roots of
all plants were dipped in soluble 20-20—20 starter
fertilizer solution. The field was irrigated overhead
after transplanting.

Fertilizer was applied to the field at a rate of 56

kg/ha N, 112 kg/ha P andll2 kg/ha K 0. Fifty-six kg/ha

205 2

nitrogen was sidedressed after fruit set. The previous
cover crop was alfalfa. Irrigation was applied when
necessary. Fungicides and insecticides were applied when
necessary to control foliar diseases and insects.

The tomato experiment was designed as a randomized
complete block with 3 replications in a factorial arrange-
ment of 6 cell sizes and 2 production locations. Each
plot contained 28 plants in 2 rows of 1A plants each with

2 feet between plants and A feet between rows. Cell size

100A of Speedling peppers was the wrong cultivar; therefore

37

the pepper experiment was divided into two sections and
Michigan and Florida yield data were analyzed as two
separate randomized complete block designs with 3 repli-
cations. Twenty-eight plants were transplanted into each
of 33 plots in 2 rows of 1A plants with 2 feet between
plants and A feet between rows.

Tomato and pepper seedling leaf area and shoot dry
weight data were used to determine relative growth rate and
net assimilation rate. This growth analysis method was
discussed in detail by Leopold and Kriedemann in Plant
Growth and Development (27).

Relative growth rate (RGR) was calculated by the

 

formula:
_ T
RGR = 1n W2 1n M1
132 - t1
where: Wl = shoot dry weight at time 1

(.4
Re
ll

.2 shoot dry weight at time 2

d
II

time 1

('1‘
ll

time 2

RGR is an expression of the increase in weight per
unit of original weight over a time interval, t. It is a
measure of how quickly a plant is growing.

Unit leaf rate or net assimilation rate (NAR) can be
expressed as:

NAR = W2 — wl (1n L2 - 1n L1)

 

t2 - t1 L2 - Ll

38

where: Wl = shoot dry weight at time 1
W2 = shoot dry weight at time 2
L1 = leaf area at time 1
L2 = leaf area at time 2
t1 = time 1
t2 = time 2

NAR is the rate of increase in dry weight per unit leaf
area. The term is a physiological index representing
photosynthetic efficiency of the plant: the plant's capacity
to increase in dry weight with respect to the area of its
assimilatory surface. Together, RGR and NAR can be used to
analyze the response of plant growth to various environmental
conditions (27).

Two tomato and pepper plants per plot were harvested 1,
2 and 3 weeks after transplanting for growth analysis.
Plant height, leaf number, leaf area and dry weight were
collected. Relative growth rate and net assimilation rate
were calculated for 3 one-week growth periods following
field-setting. Plant height, shoot fresh weight, shoot dry
weight, fruit number, and fruit weight were measured for
weeks 3 to 8 after transplanting from 2 tomato and pepper
plants per plot. All results were analyzed by analysis of
variance and means separated by Duncan's multiple range
test, 5% level.

Mature tomato and pepper fruit were harvested weekly

39

from the remaining 1A plants per plot. Tomatoes showing
red coloration and peppers over 6.A cm in diameter and
length were considered mature. Tomatoes were graded as
large fruit (6.7 cm or larger fruit), small fruit (less
than 6.7 cm in diameter) and culls. Peppers were graded
into large fruit (greater than 6.A cm in length and
diameter) and culls. Fruit number and fresh weight of
each grade per plot were recorded.

Tomatoes harvested during the first 2 weeks were
considered early yield, fruit harvested from the third and
fourth weeks were midseason I yield, and fruit harvested
during the fifth and sixth weekswere midseasonII yield.
Tomato fruit harvested during the seventh and eight weeks
were late yield. Results are discussed as early yields
and total yields.

Pepper fruit harvested during the first week were
early yield. Pepper fruit harvested during the second and
third weeks were considered midseason I yield. Pepper
fruit harvested from the fourth and fifth weeks were
midseason II yield and pepper fruit harvested from the sixth
and seventh weeks were late yield.

All yield results were analyzed by analysis of
variance. Treatment sums of squares were partitioned into
linear, quadratic and cubic effects through trend analysis.

The depth, area and volume of TODD planter flats of

root cell sizes 080 through 175 were calculated (Table 5).

A0

Linear regression analysis was used to determine what
relationship, if any, existed between these three
variables and early season and total yields of tomato
and pepper transplants produced at MSU and in Florida.
All results were analyzed by use of a regression F test

in the analysis of variance.

Table 5. Depth, area and volume of root cell sizes of
TODD planter flats produced by Speedling, Inc.

 

 

Root cell Root cell Root cell
Root cell depth area volume
sizeZ (cm) (cm?) (cm3)
080 3.2 A.1 A.A
O8OA A.1 A.1 5.6
100A 7.2 7.8 18.8
125 A.6 10.1 15.A
150 6.A 1A.5 30.7
175 6.A 18.7 39.5

 

zRoot cell sizes are designations given to TODD planter
flats. The numbers represent one side of a square cell, in
hundredths of an inch. Thus an 080 cell measures 0.80
inches to a side. Root cells differ in depth, area and
volume.

Al

C. A Comparison of Ethylene and 002 Production of Tomato and
Pepper Transplants Produced at Michigan State University
and at Seedling, Inc. in Florida in 1981.

 

 

Speedling tomato and pepper transplants were shipped by
air freight and arrived at Michigan State University on May
27, 1981. The plants were enclosed in cardboard boxes
with air holes for ventilation.

An experiment was performed on the day of their
arrival to determine if Speedling plants grown in Florida
produced increased amounts of ethylene or CO2 gas as a
result of mechanical stress created by drought, temperature
extremes, crushing, or confinement during shipment.

Single tomato or pepper transplants were placed in
quart glass Ball jars with screw tops. A rubber septum was
inserted snugly into a hole in the top of each Ball jar to
allow for extraction of gases produced in the container
with a plastic syringe.

Treatments consisted of a control jar of laboratory
air and A replications of whole Speedling or Michigan-grown
125 tomato and pepper transplants, each in a separate jar.
Also included in separate jars were a single tomato shoot,
a tomato root, a pepper shoot and a pepper root from
each growing location. The severed shoots and roots
served as controls producing increased levels of stress
ethylene for comparative purposes.

Ethylene levels were monitored at l, 2 and 12 hours

and CO2 levels were monitored 1 and 12 hours after sealing

A2

the jars. Ethylene levels were measured by gas chromato—

graphy and CO levels were measured by a CO analyzer. All

2 2

results were analyzed by analysis of variance and means

separated by Duncan's multiple range test, 5% level.

D. A Comparison of the Growth of Tomato Seedlings at Two
Spacings in TODD Planter Flats of Various Cell Sizes.

 

 

Pik—Red tomato seeds were pregerminated and sown
November 2A, 1981, as described above, in 6 TODD flats
each of root cell sizes 080, 080A, 100A, 125, 150 and 175.
The plants were grown in the greenhouse at Michigan State
University. In 3 of the flats of each root cell size, 25
seeds were planted in adjacent root cells in a square of
5 root cells to a side. In the other 3 flats of each root
cell size, 25 seeds were planted so that the distance
between seedlings was approximately 8 cm by 8 cm regardless
of root cell size. Since the spacing between adjacent
plants increases drastically with increasing root cell
size this experiment was performed to judge the effect of
root cell size on seedling growth independent of plant
spacing.

Leaf area, plant height and shoot dry weight were
measured weekly for 5 weeks,beginning December 8, 1981.
RGR and NAR were calculated, as described above.

The experiment was designed as a randomized complete
block in a factorial arrangement, with each flat as a

replication. Data were analyzed by analysis of variance.

A3

Trend analysis was used where appropriate.

Results

A. The Effect of Root Cell Size and Production Location
on Yield of Pik-Red Tomato Transplants in 1980.

 

 

There was no difference in mortality between Speedling
and Michigan tomato plants in 1980. Between 5 and 6 plants
survived in each plot.

Age of transplants at field-setting had no significant
effect on tomato yield, except for 175—size plants, where
A-week-old transplants produced greater early yields than
6—week—old transplants. lichigan-grown 100 and 175-size
plants, A weeks old attransplanting,produced the largest
early yields (Table 6, Figure 1). All 080—size and all
Speedling plants produced low early yields. The other
treatments were intermediate. It appears that as the volume
of the root cell increased, early yields also increased.
Early yields were increased up to lO-fold when plants
were grown in size 175 containers. Michigan-grown trans-
plants produced greater early yields than Speedling-grown
transplants of comparable root cell sizes.

There were no significant differences among any of
the treatments in late and total yields (Table 6, Figures 2

and 3).

AA

 

 

Table 6. Influence of different sizes of root cells of
TODD planter flats, seeding date and location
of transplant production on yield of Pik—Red
tomato plants grown at Sodus, MI 1980.
Rootw ' Yield (kg/ha)X
cell Earlyyz Mid-Z LateZ Z
Treatment size season season season Total
Speedling of 080 0a 86A7a 39675a A8322a
Florida 100A 509ab 9970ab A2727a 53205a
125 lll9ab 9257ab 51170a 615A7a
MSU O80 305ab 2OOAlcde A95A2a 69889a
sown 100A 3357de l9l25cde 50763a 732A6a
April 30, 1980 125 1933abc 16887cd A7915a 66735a
150 A273Cd 25331ef A6389a 7609Aa
175 A68OCd 31231f 359lla 71821a
MSU 080 l83labc 15972bc 57783a 75A8Aa
sown 100A 68l6de 25A33ef 38A5Aa 70601a
May 13, 1980 125 26A5Cd 23398de A0997a 671A2a
150 A069Cd 258A0ef 3895Aa 68363a
175 13123e 2A212ef 22177a 65921a

 

wRoot cell sizes are designations given to TODD planter
The numbers represent one side of a square cell,

flats.

in hundredths of an inch.

inches to a side.
volume of the cell (see Table 5).

XYield measurements are means of 3 replications.
season yields were harvested August 1A and 22, midseason
yields were harvested August 28 and September A, and
late season yields were harvested on September 11 and 17;
total yield is a total of all harvests.

yA square root data transformation was performed to

maintain homogeneity among variances.

Thus an 080 cell measures 0.8
Root cells differ in depth, area and

Early

z ; . .
Means separation in columns by Duncan's multiple range

test,

5% level.

A5

Figure l. The influence of sowing date, location of
production, and root cell size on the early
yield of Pik-Red tomatoes in 1980.

A6

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Figure 2. The influence of sowing date, location of
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yield of Pik-Red tomatoes in 1980.

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Figure 3. The influence of sowing date, location of
production, and root cell size on the total
yield of Pik-Red tomatoes in 198 .

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B. The Effect of Root_Cell Size and Production Location
on Development and Yield of Pik-Red Tomato and Lady
Bell Pepper Transplants 1981.

 

 

 

Height, leaf area and shoot dry weight of 2-week-old
tomato and pepper plants were greatest for seedlings grown
in larger root cell sizes (Table 7). The same trend was
observedefi:transplanting for A-week-old Michigan and
Speedling tomato and pepper seedlings (Tables 8 and 9).
Plants from larger root cells were taller and had more
leaf area and shoot dry weight than plants from smaller
root cells.

Speedling pepper plants were significantly taller
than Michigan pepper transplants at field—setting. Michigan
pepper plants had slightly less leaf area and shoot dry
weight than Speedling peppers. Height of Michigan and
Speedling tomato plants were not generally different for
comparable root cell sizes. Michigan tomato plants had
greater leaf area and shoot dry weight than Speedling
plants at transplanting (Tables 8 and 9).

Thirteen and nine days after transplanting (respectively)
Pik—Red tomato and Lady Bell pepper plants of larger root
cell sizes were taller and possessed significantly greater
leaf number, leaf area and shoot dry weight than did
plants of smaller root cell sizes (Tables 10 and 11).

This relationship existed for plant height and shoot dry
weight until approximately 6 to 7 weeks after field-

setting, when treatment differences were negligible.

52

Michigan tomato plants were greater in height, leaf area

and shoot dry weight than were Speedling tomato plants

at every root cell size 20 days after transplanting

(Table 12). Michigan pepper plants were significantly
shorter than Speedling pepper plants 20 days after trans-
planting (Table 13). However, Michigan pepper plants
possessed greater leaf area than Speedling plants for all
root cell sizes at this time. Shoot dry weight increased
significantly with greater root cell size, but was generally

not different from the two production locations.

Table 7. The influence of root cell size on size of
Michigan tomato and pepper plants 1A days after
sowing.

 

Heighty Leaf AreaZ Shoot dry weightZ

2
(cm) (cm ) (a)
Root cell size Tomato Pepper Tomato Pepper Tomato Pepper

 

 

 

 

080 5.Aa 5.53b 1.0 1.1 0.01 0.01
080A 6.0ab 5.0a 1.3 0.9 0.03 0.01
100A 8.30 5.6ab0 2.3 1.1 0.03 0.02
125 8.90 9.0d 2.6 1.A 0.0A 0.03
150 7.5b0 6.80 3.2 2.1 0.0A 0.03
175 8.30 6.3b0 3.1 1.9 0.0A 0.02

 

yHeight measurements are the means of A plants. Mean separation
in columns by Duncan's multiple range test, 5% level.

ZLeaf area and shoot dry weight measurements are the means of
A seedlings sampled per treatment.

53

Table 8. The influence of root cell size and location
of production on the size of Pik—Red tomatoes

28 days after sowing.

 

 

Root cell Heighty Leaf areaZ Shoot dry weightz
Source size (cm) (cm2) (g)
Michigan 080 10.1a 6.5 0.07
080A 11.9b0 7.9 0.09
100A 20.3de 33.5 0.27
125 22.2fg A5.8 0.30
150 26.8h 75.7 0.A2
175 20.9def 70.5 0.AA
Speedling 080 13.10 5.5 0.08
080A 9.3a 6.0 0.06
100A 10.7ab 7.A 0.12
125 23.3g 36.2 0.2A
150 19.5d 39.1 0.32
175 21.6ef A1.8 0.37

 

yHeight measurements are the means
separation in columns by Duncan's

5% level.

of A plants. Mean
multiple range test,

ZLeaf area and shoot dry weight measurements are the means
of A seedlings sampled per treatment.

5A

Table 9. The influence of root cell size and location of
production on the size of Lady Bell peppers 28
days after sowing.

 

Root cell Heighty Leaf areaZ Shoot dry weightZ

 

Source size (cm) (cm2) (g)
Michigan 080 7.0a 8.9 0.05
080A 7.3a 9.1 0.06
100A 10.3b 16.1 0.12
125 12.1b0 25.A 0.18
150 13.70d 28.6 0.23
175 15.0de A7.6 0.15
Speedling 080 l8.Af 15.6 0.15
080A 16.3ef 11.5 0.11
125 l8.Af 23.A 0.25
150 23.5g A3.3 0.A2
175 27.0h A6.7 0.A9

 

yHeight measurements are the means of A plants. Mean
separation in columns by Duncan's multiple range test,
5% level.

ZLeaf area and shoot dry weight measurements are the means
of A seedlings sampled per treatment.

55

 

 

Table 10. The influence of root cell size and location
of production on the growth of Pik-Red
tomatoes 13 days after transplanting into the
field.
2 z Leafz Shoot dryZ
Root cell Height Leaf area weight
Source size (cm) number (0m2) (g)
Michigan 080 16.3b0 5.5ab A2.8b 0.A2abc
080A 17.9cd 6.0b0 69.10 0.7lcd
100A 20.6de 6.0b0 69.30 0.600d
125 23.3ef 6.5b0d 100.6d 0.78de
150 2A.lf 6.7cd lll.Ad 1.06e
175 23.3ef 7.3d 107.1d 1.06e
Speedling 080 13.3a A.8a 1A.5a 0.23a
080A 12.3a A.8a l3.Aa 0.2lab
100A 1A.6ab 5.8abc 25.Aab 0.3Aabcd
125 20.8de 6.0bc 38.1b 0.5Aabcd
150 17.9cd 6.3bcd 39.7b 0.50ab0d
175 23.11ef 6.80d A7.7bc 0.8lde

 

2Figures are the means of 2 plants per plot with 3
Mean separation in columns by Duncan's
level.

replications.
multiple range test,

5%

56

Table 11. The influence of root cell size and location of
production on the growth of Lady Bell peppers
9 days after transplanting into the field.

 

Leafz Shoot dryz
Root cell HeightZ LeafZ area weight

 

Source size (0m) number (0mg) (g)

Michigan 080 7.5a 6.1bcd 16.9ab 0.11a
080A 8.8ab 5.8abc 18.0ab 0.19ab
100A 11.80 6.8def 28.Abed 0.29b0
125 11.3bC 8.0fg 35.10d 0.380d
150 10.Abc 7.7efg 38.6de 0.38cd
175 12.80 8.3g 50.9e 0.52a

Speedling 080 16.8d A.7a 11.7a 0.153b
080A 16.8d 5.3ab 23.6abc 0.15ab
125 19.0d 6.2b0d 27.2bed 0.27abc
150 23.2e 6.30de 3A.20d 0.39cd
175 19.5d 7.3defg 32.5Cd 0.A9d

 

2Figures are the means of 2 plants per plot with 3
replications. Mean separation in columns by Duncan's
multiple range test, 5% level.

57

Table 12. The influence of root cell size and location of
production on the growth of Pik—Red tomatoes
20 days after transplanting into the field.

 

Root cell HeightZ Leaf areaZ Shoot dry weightZ

 

Source size (cm) (cm2) (g)

Michigan 080 35.9cd 368.1b A.06ef
080A 3A.80 381.5b 3.030d
100A A0.0de 553.20 A.73f
125 A2.6e 632.70d 5.90g
150 A1.7e 727.9d 5.73g
175 A3.9e 6A1.20d 5.90g

Speedling 080 26.Aa 152.0a 1.52ab
080A 25.3a 168.8a 1.26a
100A 29.3ab 186.2a 2.19b0
125 36.00d 276.2ab 3.0000
150 31.5b0 275.3ab 2.690d
175 36.30d 378.2b 3.60de

 

zFigures are the means of 2 plants per plot with 3
replications. Mean separation in columns by Duncan's
multiple range test, 5% level.

58

Table 13. The influence of root cell size and location of
production on the growth of Lady Bell peppers
20 days after transplanting into the field.

 

Root cell Heightz Leaf areaZ Shoot dry weightZ

 

Source size (cm) (0m2) (g)

Michigan 080 12.6a 60.9ab 0.A5a
080A 13.8ab 7A.9ab0 0.58ab
100A 18.00d 126.70de 1.0A0d
125 15.3ab0 137.6de 0.90bc
150 17.6b0d 151.0de 1.150d
175 17.80d 16A.7e 1.31d

Speedling 080 17.2de 36.0a 0.50a
080A 16.9b0d 3A.5a 0.AAa
125 20.0d 50.8ab 0.92b0
150 23.8e 75.2abc 0.96bc
175 25.3e 100.2b0d 1.28d

 

2Figures are the means of 2 plants per plot with 3

replications. lean separation in columns by Duncan's

multiple range test, 5% level.

59

Net assimilation rate and relative growth rate calcu-
lated for 3 weeks following transplanting were not statis-
tically different for either tomato or pepper plants grown
in different root cell size treatments. However, RGR and
NAR decreased slightly from field-setting to 10 days after
field-setting for transplants of all treatments.

In general, Speedling tomato transplants were shorter
and possessed less leaf area and shoot dry weight than
Michigan plants of corresponding cell sizes from trans-
planting until 5 weeks later. Speedling pepper plants were
taller and possessed less foliage than did Michigan pepper
plants of corresponding cell sizes until 5 weeks after
field settings. Tomato and pepper transplants of all root
cell sizes and locations did not differ in height or shoot
fresh weight six weeks after transplanting. At this point,
plant size appeared the same for all treatments (Tables
1A and 15).

Differences in earliness of flowering and fruit-setting
appeared 5 to 7 weeks following transplanting (Tables 1A and
15). Michigan and Speedling tomato plants grown in 175—
size root cells produced a significantly greater number of
flowers and small unripe fruit than plants grown in 080-
size cells at this time. Fruit weight also increased with
larger root cell size. Michigan tomato plants produced a
significantly greater weight of fruit than Speedling tomato

plants at most comparable root cell sizes but there were

6O

virtually no differences in number of fruit. Michigan
pepper plants grown in 175-size root cells produced a
greater weight of fruit at 7 weeks after transplanting

than did comparable Speedling plants (Table 15).

Table 1A. The influence of root cell size and location
of production on the growth of Pik-Red tomatoes
A7 days after transplanting into the field.

 

ShootZ ShootZ

 

z z Fruitz fresh dry
Root cell Height Fruit weight weight weight
Source size (cm) number (g) (kg) (g)
Michigan 080 80.7a 15.0ab0 16A.2ab 1.6a 132.50
080A 78.3a 16.8ab0 231.7b0 1.5a 106.7b0
100A 82.3a 18.30 292.50d 1.5a 121.7b0
125 79.9a 21.70 AA1.7ef 1.5a 12A.2b0
150 8A.3a 22.00 511.7fg 1.8a 1A0.8c
175 79.5a 20.50 605.8g 1.9a 139.20
Speedling 080 78.8a 9.8ab 80.8a 0.9a 88.3ab
080A 75.2 9.0a 55.8a 0.7a 65.0a
100A 78.8a 16.0ab0 135.0ab 1.3a 131.7a
125 77.5a 22.00 283.30 1.3a 105.8b0
150 73.1a 17.50 222.8b0 1.1a 90.0ab
175 77.8a 23.20 393.3de 1.Aa 106.7bc

 

ZFigures are the means of 2 plants per plot with 3
replications. .Mean separation in columns by Duncan's
multiple range test, 5% level.

61

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Tomato and pepper fruit were harvested from 1A plants
per plot beginning on August 7, 1981, 10 weeks after
transplanting. A number of fruit were graded as culls
due to blossom end rot in the first harvest. The incidence
of blossom end rot decreased the second week of harvest.

Trend analysis was used to analyze the yield data in
this factorial experiment. Trend analysis determines if
the response of the experimental units to varying levels
of a treatment is linear, quadratic or cubic. A linear
response indicates that the response of the experimental
units to the levels of a treatment fits a straight line
or first degree polynomial equation. A quadratic response
fits a. parabolic curve or second—degree polynomial
equation. A cubic response fits to a bi-directional curve

or third-degree polynomial equation (29).

Tomato Fruit Harvest

 

Total early yield of Pik-Red tomatoes increased linearly
as root cell size of TODD planter flats increased (Table
16). Early yield of large fruit also increased linearly
with increased root cell size (Table 16, Figure A). Plants
grown in 175-size root cells produced more than twice
as much early yield as plants grown in 080 root cells.
Location of transplant production also had a signifi—
cant effect on early yield. Michigan plants across most

root cell sizes produced about A0% higher early yields

63

than Speedling transplants (Table 16, Figure A).

Cull fruit number and weight, small fruit number and
weight, large fruit number and total fruit number
harvested during the early yield period were not signifi-
cantly different among root cell sizes or between locations.

Total fruit yield for the 1981 season increased
linearly with increasing root cell size (Table 17, Figure
5). Plants grown in 175-size rootcmfljjsproduced up to
25% greater total yield than those grown in O80-size root
cells. There were no differences in total yield between
Speedling and Michigan transplants. Total large tomato
yield increased linearly and quadratically with increased
root cell size. Tomato plants grown in size 125, 150 and
175 root cells produced more large fruit during the season
than plants grown in size 080, 080A and 100A root cells.
Michigan transplants produced 23% more large fruit than
Speedling plants across all root cell sizes. Total small
and cull fruit yields were not significantly different for
either root cell sizes or locations of transplant
production.

Total large fruit number of Pik-Red tomatoes harvested
over the growing season increased linearly with increased
.Poot cell size (Table 18). There was a significant
ciifference in the number of large fruit between locations
C>f production, with Michigan plants producing 18% more
Juarge fruit than Speedling plants. There were no

dzifferences among treatments and between locations of

6A

Table 16. The influence of root cell size and location
of transplant production on early yield of
Pik—Red tomato plants in 1981.

 

 

 

 

 

 

Total earlyZ Large fruitz
Root cell size yield yield
and source (kg/ha) (kg/ha)
Root cell size
080 82A8 A905
080A 7528 3001
100A 913A 3699
125 12789 9171
150 1A570 90A7
175 1793A 12339
linear ** **
quadratic NS *
cubic NS NS
Location of
transplant production
Michigan 13625 853A
Speedling 9776 5520
Main effect ** *
ZTomatoes were harvested from 1A plants per plot. Yield

figures are the means of 3 replications. Early season
yields were harvested during the first 2 weeks of the
harvest season on August 6 and August 1A, 1981. Large
fruit yield refers to the weight of marketable fruit
harvested greater than 6.7 cm in diameter. Fruit weight
was converted to kilograms/hectare.

* **
’ Significant at the 5 and 1% levels, respectively.

65

Figure A. The influence of root cell size and location
of transplant production on early yield of
Pik-Red tomatoes in 1981.

66

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68

Figure 5. The influence of root cell size and location
of transplant production on the total yield
of Pik—Red tomatoes in 1981.

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71

production for total small fruit number, total cull fruit
number and total fruit number produced during the 1981
growing season.

There were no significant interactions at any time
between root cell size and location of production in any
category of fruit number or weight.

Most of the tomato fruit was harvested during the
early and midseason II harvesting periods. In general,
over the course of the picking season, a similar number of
large and small fruit were harvested for plants of all
root cell sizes (Table 18). Almost twice as much large
fruit weight as small fruit weight was harvested through-
out the season for plants of all root cell sizes (Table 17).
Cull fruit weight amounted to 30 to 50% of the total tomato
fruit yield. Most of the cull fruit was harvested during
the early season.

Total early yield of Michigan and Speedling Pik—Red
tomatoes was highly correlated at the 1% level with
both the area and volume of the root cell in the TODD
planter flat in which they were produced (Figures 6 and 7).
As the area and the volume of the root cell increased,
total early tomato yields increased. Depth of the root
cells was not highly correlated with tomato early yield.

Midseason and late tomato yield production was not
significantly correlated with either depth, area or volume

of the root cell. However, the total large fruit yield of

72

Figure 6. The effect of root cell surface area on
early yield of Pik—Red tomatoes, 1981.

73

O
2

 

«a: 3.0. «.2 cc

— Michigan
"m- Speedling

0 5
Gum; \St QM 0.3.20.5

15 20

1O
ROOT CELL AREA (Cm?)

7A

Figure 7. The effect of root cell volume on early
yield of Pik—Red tomatoes, 1981.

75

20

fl

(0

C

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X

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l~ mm Speedling

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ROOT CELL VOLUME (Cm3)

 

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76

marketable tomatoes was highly correlated at the 1% level

with area and volume of the root cells (Figures 8 and 9).

Increased root cell area and volume resulted in more large
fruit over the harvest season for tomato transplants from

both seedling locations. The depth of root cells was not

significantly correlated with tomato yields at any time

during the growing season.

Pepper Fruit Harvest

 

Total early yields of Michigan Lady Bell peppers
increased linearly with increased root cell size (Table 19,
Figure 10). Total early yields of Speedling peppers
increased linearly and quadratically with increased root
cell size. Total early yields of Speedling, 080-, 125-
and l50-size plants were similar, while that of 175-size
Speedling plants was greater, creating a significant linear
and quadratic response. Use of 175-size root cells
resulted in up to a 50% increase in early yield of Lady
Bell pepper transplants over both production locations.
Early yields of large fruit increased linearly with
increased root cell size for Michigan transplants. There
were no differences in early yields of large fruit between
cell sizes for Speedling transplants. Early yields produced
by Michigan and Speedling transplants of comparable root
cell sizes appeared to be similar.

There were no differences in total yield and total

77

Figure 8. The effect of root cell area on total
large fruit yield of Pik—Red tomatoes, 1981.

TOTAL LARGE TOMATO YIELD (X 103 kg / ha)

20

 

15
1O
5
— Michigan
mm Speedling
0 5 1o 15 20

ROOT CELL AREA (cmz)

79

Figure 9. The effect of root cell volume on total
large fruit yield of Pik-Red tomatoes, 1981.

20

.1.
0|

 

.5
0

0|

— Michigan
mm Speedling

TOTAL LARGE TOMATO YIELD (X 103 kg /ha)

0 1O 20 3O 4O

ROOT CELL VOLUME (cm3)

81

Table 19. The influence or root cell size and location
of transplant production on the early yield
of Lady Bell pepper plants in 1981.

 

Total earlyZ Large fruitZ

 

 

 

Root cell size yield early yield
and source (kg/ha) (kg/ha)
Root cell size
Michigan
080 6671 6511
080A 7223 6802
100A 7732 6816
125 8357 7790
150 11932 115A0
175 10973 10261
linear ** *
quadratic NS NS
Speedling
080 828A 812A
O80A 8A15 8255
125 719A 7121
150 8A58 8357
175 11176 10726
linear * NS
quadratic * NS

 

zPeppers were harvested from 1A plants per plot. Yield
figures are the means of 3 replications. Early season
yield was harvested during the first week of the harvest
season on August 12, 1981. Large fruit yield refers to
the weight of marketable fruit greater than 6.A cm in
diameter and length. Michigan and Speedling treatments
were analyzed as separate experiments to avoid an
unbalanced analysis created by the absence of treatment
Speedling 100A.

* xx
’ Significantly at the 5 and 1% levels, respectively.

82

Figure 10. The influence of root cell size and location
of production on the total early yield of
Lady Bell peppers in 1981.

83

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large pepper yield for plants of any root cell treatment
(Table 20. Figure 11). Total cull yield increased

linearly and quadratically with increased root cell size of
Speedling transplants, with 175-size plants producing the
most culls.

There were no differences among root cell sizes or
between locations for cull numbers and weights, and small
fruit numbers and weights during early, midseason and
late harvest periods. There were no significant differences
between plants of different root cell sizes and locations
in total small fruit numbers or yield, total large fruit
numbers or yield and total fruit numbers or yield (Tables
20 and 21). There were no significant interactions between
root cell size and location of production for any parameter
measured.

The majority of the large peppers were harvested during
the early and midseason II harvest periods from root cell
sizes 100A, 125, 150 and 175. Cell sizes 080 and 080A
produced the greatest percentage yield during the midseason
I harvest period. Cull peppers constituted less than 5%
of the total pepper fruit weight throughout the season.

Total early yield of Michigan Lady Bell peppers was
highly correlated at the 1% level with both the area and
the volume of the root cells of TODD flats (Figures 12 and
13). Total early yields of Speedling peppers was not

highly correlated with either the area or the volume of the

85

Table 20. The influence of root cell size and location
of transplant production on the total yield

of Lady Bell pepper plants in 1981.

 

Total largey Total cully Total fruityz

 

 

 

Root cell size fruit yield yield yield
and source (kg/ha) (kg/ha) (kg/ha)
Root cell size
Michigan
080 2562A 6A1 26260
080A 261A7 1557 27699
100A 2A329 1352 25680
125 2521A 171A 26932
150 31563 903 32A38
175 27237 1687 28920
linear NS NS NS
quadratic NS NS NS
Speedling
080 27586 872 28A58
080A 303A6 772 31117
125 293A3 567 29910
150 29551 929 30A76
175 31056 1600 32656
linear NS * NS
quadratic NS * NS

 

ineld figures are means of 3 replications.

was converted to kilograms/hectare.

Fruit weight

ZTotal fruit yield is the total yield of all fruit

harvested during the season. Michigan and Speedling
treatments were analyzed as separate experiments to avoid
an unbalanced analysis created by the absence of treatment
Speedling 100A.

* xx
’ Significant at the 5 and 1% levels, respectively.

86

Figure 11, The influence of root cell size and location
of production on the total yield of Lady
Bell peppers in 1981.

87

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89

Figure 12. The effect of root cell area on early yield
of Lady Bell peppers, 1981.

90

15

1O

— Michigan
m"- Speedling

PEPPER EARLY YIELD (x 103 kg / ha)

0 5 1o 15

ROOT CELL AREA (cmz)

 

20

91

Figure 13. The effect of root cell volume on early
yield of Lady Bell peppers, 1981.

PEPPER EARLY YIELD (x 103 kg / ha)

15

10

92

 

— Michigan
mm Speedling

1O 20 3O

ROOT CELL VOLUME (cm3 )

4O

93

root cells. The depth of the container did not appear
to influence early yield of peppers as it was never
highly correlated with early yield.

In general, midseason, late and total pepper yields
were not significantly correlated with either depth, area

or volume of the root cell.

9A

C. A Comparison of Ethylene and C02 Production of Tomato and
Pepper Transplants Produced at Michigan State
University and athpeedling, Inc. in Florida in 1981.

 

 

 

All tomato and pepper seedlings and excised plant
parts produced increased levels of ethylene and CO2
compared to the laboratory air control at 2 and 12 hours
after placement in glass Ball jars (Tables 22 and 23).
Intact Michigan tomato seedlings produced significantly
greater amounts of ethylene and 002 at 1 hour after place-
ment in glass jars than the Speedling tomato seedlings. The
Michigan pepper seedlings produced a similar amount of

ethylene and CO as compared to the Speedling pepper seed-

2
lings.

Two hours after placement in the jars, the ethylene
production of whole seedlings had increased slightly over
production at 1 hour (Table 22). However, the Michigan
tomato seedlings still produced a greater amount of
ethylene than the Speedling tomato seedlings. There was no
difference in the levels of ethylene produced by Michigan
and Speedling pepper seedlings.

Twelve hours after placement in the jars, Michigan
tomato seedlings had produced significantly greater levels
of ethylene and CO2 than Speedling tomato seedlings (Tables
22 and 23). The levels of ethylene and CO2 produced by
Michigan and Florida pepper seedlings were not significantly

different. The levels of ethylene and CO produced by

2

tomato and pepper plants of both locations increased after

enclosure in glass jars for 12 hours as compared to the

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95

 

 

 

 

 

 

 

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97

levels of these gases detected after 1 and 2 hours of

enclosure.

D. A Compgrison of the Growth of Tomato Seedlings at Two
Spacings in TODD Planter Flats of Various Root Cell
Sizes.

 

 

Tomato, leaf area, shoot fresh weight, and shoot
dry weight increased in a linear manner with increased
root cell size at 15 days (Table 2A). Height also increased
with increased root cell size, but in a linear and quadratic
manner. At 1A days of age, increased plant spacing resulted
in significantly increased height, shoot fresh weight and
shoot dry weight of tomato seedlings grown in all root cell
sizes. No interactions between root cell size and spacing
were significant at this time.

When the tomato seedlings were 30 days old, leaf area,
fresh weight and dry weight increased in a linear manner
with increased root cell size (Table 25). There were no
significant trends in plant height among root cell size
treatments. Increased spacing in the flat resulted in
significantly decreased plant height and increased shoot
dry weight for seedlings of all root cell sizes. A
significant interaction between plant spacing and root
cell size was noted for fresh weight.

At A5 days of age, plant height, leaf area and shoot
fresh weight increased in a quadratic manner with increased
root cell size (Table 26). This quadratic response was

significant because the plants grown in root cell size

98

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99

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100

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oaOIzooIm: no nezonw one no wnaoono ono onao aaoo no oonooaena .cm oanoe

101

150 were of a larger size than plants grown in size 175
root cells. Shoot dry weight increased in a linear and
quadratic manner with increased root cell size. Increased
flat spacing resulted in decreased plant height. Signifi-
cant interactions between root cell size and spacing were
noted for plant height, leaf area and shoot fresh weight.

Interactions between spacing and root cell sizes were
significant only when tomato plants were between A and 7
weeks of age (Tables 25 and 26). At smaller root cell
sizes, the differences between plant size at different
spacings were negligible throughout the experiment.

However, when simple effects were examined, plants of root
cell sizes 125 and 150 grown at the wider spacing were
taller and possessed greater leaf area and fresh weight

at A5 days of age than plants of comparable root cell sizes
at normal spacings. In all cases, when simple effects and
interactions were graphed, plants grown in root cell size
150 at the wide spacing were largest. Plants grown in

root cell size 175 at wider spacings were smaller than
plants of the same cell size at normal spacing and root cell
size 150 at both spacings.

The results of the growth analysis of seedling tomatoes
at 6 different root cell sizes and 2 different flat spacings
were variable. Relative growth rate (RGR) and net assimi-
lation rate (NAR) varied slightly with different root cell

sizes and spacings, but were generally not significantly

102

different for separate growth periods. There were no
significant differences in the average RGR and NAR of all
root cell sizes from the A growth periods. Root cell size
treatments 080 and 150 maintained the greatest RGR and

NAR throughout the experiment.

Discussion and Conclusions

 

Tomato and pepper seedlings grown in larger size root
cells were taller and possessed greater leaf area and shoot
dry weight at A weeks of age, just before field-setting.
Nicklow and Minges (37) also found that transplants
produced in larger containers were stockier and possessed
more leaves at the first cluster. They believed that
increased container space influenced the physiological
condition of the transplant before field—setting. However,
Knavel (2A) proposed that larger containers hold enough
fertile soil mix to support adequate root development
until field-setting, while transplants grown in small
containers encounter nutrient starvation more quickly.

After field—setting, the tomato and pepper seedlings
from both production locations grown in larger size root
cells exhibited greater height, leaf number and shoot dry
weight for 6 weeks. From 5 to 7 weeks after field—setting,
these tomato and pepper seedlings also produced a greater
number of flowers and small unripe fruit than plants grown

in smaller size root cell. These observations were not

103

unexpected since Nicklow and Minges found that larger
container size resulted in a faster overall growth rate
which in turn resulted in earlier tomato flowering (37).
The depth and volume of the rooting medium are known
to influence the rate of growth of the plant root system.
Plant roots tend to grow more rapidly if fewer structural
limitations are imposed (18). Leonard and Head (27) noted
that until fruit formation, the tomato root system under-
goes rapid horizontal and vertical growth. They found
that the rate of growth of tomato roots was closely related
to the rate of new fruit production. With a more expansive
root system, a plant has greater capacity for water and
nutrient uptake which in turn promotes greater vegetative
growth and fruit development. It may be that transplants
grown in larger root cell sizes were able to produce a
larger, more efficient root system both before and after
field setting. It is important to note that the entire
root ball was retained by the plant at transplanting. New
root initiation from the center section of the root ball
had occurred within 1 week after transplanting for all
treatments. However, the 175-size root ball had a much
greater surface area for new root initiation and appear—
ed to undergo more root initiation than did the 080-size
root ball. A larger initial root system which promotes
increased uptake of water and nutrients and undergoes

greater new root initiation may account for the earlier

10A

maturity of plants grown in larger size TODD planter flats.
The results of the tomato and pepper root cell size
experiments of 1980 and 1981 were very similar. Seedlings
grown in larger size root cells produced significantly
greater early yields in 1980 and 1981 than those grown in
smaller size root cells. Many researchers have found
that larger containers and greater space per plant resulted
in earlier flowering and greater early yield (2A, 25, 26,
37, A0, A2). Transplants grown in larger size root cells
also produced a significantly greater amount of large early
fruit than transplants grown in smaller size root cells.
As mentioned previously, Knavel believes that larger con-
tainers provide increased nutrient availability which can
positively influence plant size and eventual plant
maturity (2A). Plants grown in smaller root cells
reached harvest maturity approximately 1 week later than
plants of larger size root cells. Increased container
size may have allowed for the production of a larger, more
efficient transplant root system which resulted in decreased
transplant shock because of initially increased water up-
take and new root formation.
In 1981, 175-size tomato plants produced significantly
greater total yields than 080-size plants. However, in
the 1980 tomato experiment and the 1981 pepper experiment,
there were no differences in total yields between root
cell sizes. Increased early yields resulted in reduced

yields later in the season, with no net increase in yield.

105

Several researchers have also found that larger sizes of
transplant containers resulted in only increased early
yields (2A, 26). Apparently, the advantage of larger cell
size on transplant growth and early yield does not last
throughout the picking season.

The findings that early and total large yields were
highly correlated with area and volume of the root cell
and weakly correlated with cell depth agreed with the
findings of Sayre (A2). He reported that providing
increased area and volume in a flat by setting out fewer
seedlings resulted in earlier yields in the field.
However, growing the plants in deeper flats containing
33% more soil did not increase yields during 2 growing
seasons. Increased area.and volume, which allow for less
plant competition, increased nutrient availability, and
greater lateral root growth, play an important role in
influencing transplant size, maturity and yielding ability.

The large size root cells also had wider spacings
between plants owing to the physical arrangement of the
root cells in the TODD planter flats. Results of spacing
indicated that larger root cells were more critical in
forming larger plants than was wider plant spacing.
General trends showed that although increased spacing
sometimes resulted in transplants of significantly greater
weight and leaf area, increased root cell size produced

greater increases in transplant size and maturity.

106

Plants grown in 175-size root cells at wide spacings
were actually smaller than 150- or 175—size plants at
normal spacings. These findings may be due to increased
water stress imposed upon plants grown in 175—size root
cells at wide spacings. Increased sunlight penetrated
the canopy of 175 plants at wide spacing and may have lead
to drying of the peatlite mix. It has been demonstrated
that plants with a larger leaf surface area lose larger
amounts of water. If a plant loses considerable water,
even though not wilted, cell division and enlargement
decrease, the products of photosynthesis accumulate, and
rate of growth is reduced, leading to decreased plant
height, leaf area and weight (5A).

Generally, the relative growth rate (RGR) and net
assimilation rate (NAR) of plants of various root cell
sizes were not significantly different after transplanting.
This indicates that any differences in RGR and NAR which
normally accompany differences in plant size may have
occurred early in the first A weeks of development of the
transplant before field setting since all transplants
grew at a similar rate after field setting.

Judging from the outward appearance of the Florida
Speedling plants upon their arrival in Michigan in 1980
and 1981, it appeared that Speedling had hardened-off
their transplantstn;withholding nitrogen and phosphorus

prior to shipping. If so, this may account in part for

107
their relatively small size, smaller leaf area and smaller
shoot dry weight than Michigan plants of the same age of
comparable root cell sizes. Nitrogen and phosphorus are
essential major nutrients known to stimulate root and
shoot production and affect seedling growth rate and
transplant quality (33, 5A).

These apparent nutrient deficiencies may also help
to explain why Speedling plants produced smaller early
tomato yields after field setting in 1980 and 1981.
Although sufficient nutrients were present in the field
soil, the nutrient deficient condition of the Speedling
seedling may have resulted in increased transplant shock
after field setting. This in turn may have resulted in
a slower rate of initial root growth, a slower rate of
shoot growth, and overall slower maturity of Speedling plants
as compared to Michigan plants.

Transplant quality may also be affected by conditions
encountered during shipment or storage. Stressful conditions
may induce increased seedling respiration and ethylene
production (1). The increased levels of ethylene gas
sampled at 1 hour from the excised tomato and pepper shoots
may have been due to stress ethylene produced as a result
of severe mechanical injury to the seedlings. However,
since the non-injured whole tomato and pepper seedlings
of both locations produced greater levels of ethylene
throughout the experiment, it is more likely that any

differences observed in ethylene and CO2 production between

108

excised Michigan and Speedling treatments were due to size
differences among the seedlings. It would be expected
that larger plants and plant organs would produce more
ethylene and exhibit increased respiration over a 12 hour
period than smaller plant parts.

Intact Michigan tomato seedlings produced greater
levels of ethylene and 002 than did Speedling tomato plants
while Michigan and Speedling pepper seedlings produced
similar levels of ethylene and CO2 throughout the experiment.
Therefore, Florida-produced Speedling transplants did not
suffer sufficient mechanical injury or stressful conditions
to result in increased production of ethylene and C02.
Florida plants were shipped in cardboard cartons containing
air holes for ventilation, preventing the build-up of
ethylene gas and auto-catalytic ethylene production which
could result in eventual plant senescence (l). The
differences observed in ethylene and CO2 production between
Michigan and Florida seedlings may be due to seeding size
differences. Michigan tomato seedlings and shoots were
larger than Florida tomato seedlings, while Michigan and
Florida peppers possessed similar amounts of leaf area
and shoot dry weight.

It appears that any apparent reduction in quality of
Florida Speedling plants was not due to mechanical injury
or increased production of stress ethylene during shipment.
Instead, it appears that hardening the seedlings by with-

Tfiblding major nutrients may have resulted in apparent

109
nutrient deficiency symptoms such as chlorosis and
anthocyanin build-up.

In 1980, transplants were sown at 2 sowing dates in
the greenhouse. Four-week-old 175-size tomato transplants
produced greater early yields than did 6 1/2 week-old
tomato transplants of the Same size. Plant age therefore
plays an important role in influencing early yielding
ability of tomato transplants. Older transplants may
have been more root bound at the time of field-setting,
resulting in greater initial transplant shock and slower
recovery. Further investigation of the effect of plant
age on transplant yielding ability should be undertaken.

In summary, the size and dimensions of the transplant
container and the cultural practices followed at a
particular location of transplant production play important
roles in influencing transplant quality and determing the
early yielding ability of vegetable transplants. An
individual transplant container that possesses greater
area and volume but is not particularly deep is optimal
for production of greater early yield of fresh market
tomatoes and peppers. When grown at normal spacing in
the TODD planter flat, root cell size 175 produced the
largest tomato and pepper transplants, the largest early
yields and the greatest weight of marketable fruit. Early
:yields were highly correlated with root cell depth and
Eirea; the largest root cell sizes producing the largest

early yields and the greatest weight of marketable fruit.

110

The spacing of plants within the TODD planter flat was not
critical in affecting plant size or growth.

Michigan tomato transplants produced significantly
larger early yields than Speedling tomato transplants.
Speedling tomato transplants were smaller in size than
Michigan transplants of the same age before field—setting.
Speedling pepper transplants were taller but of a similar
weight and produced similar early yields when compared to
Michigan transplants of the same age. Cultural practices
involving fertilization and lighting may have played an
important role in determining transplant growth and yield-

ing ability.

CHAPTER IV
THE EFFECT OF NITROGEN AND PHOSPHORUS

FERTILIZATION OF PIK-RED TOMATO TRANSPLANTS
ON THEIR DEVELOPMENT AND YIELD IN THE FIELD

Introduction

 

Transplant nutrition has an effect on development and
yield of tomatoes in the field. Dark green, rapidly
growing plants recovered more quickly from transplanting
and produced a larger early yield of marketable fruit
(previous experiments). However, it is sometimes commer-
cially necessary to withold nutrients from vegetable
transplants to maintain acceptable transplant size and
maturity. On the other hand, judicious use of nutrients
may be able to speed up plant growth in the greenhouse
to reduce transplant production time.

It is important to provide tomato transplants with an
adequate level of essential nutrients before and after
field-setting to allow for quick transplant recovery and
growth. Phosphorus (P) plays an important role in seed-
ing growth and development. It is known to stimulate root
production, promote rapid growth in seedlings and is
necessary for cellular metabolism (5A). Early P uptake is
more iaportant in influencing early yield of tomatoes than
total P uptake (23, 36). Greater early P uptake results in

more rapid growth of tomato seedlings and an increase in early

111

112

tomato fruit yields (7, 36, Al, 56, 57).

Nitrogen (N) also strongly affects seedling growth
rate. It promotes rapid growth and chlorophyll develop-
ment, and is essential in the formation of proteins and
other compounds (33). N has been reported to be the
primary limiting element to tomato seedling growth (57).
Tiessen and Carolus (52) stated that N is necessary for
root regeneration in the tomato transplant. Moderate N
levels in the field produce larger marketable yields and
uniform development of transplanted tomatoes (19).

The availability of applied N and P is an important
factor to consider in the propagation of tomato plants, so
that seedlings are neither under-fertilized nor over-
fertilized. The balance of N to P in transplants may be
an important factor influencing tomato plant growth and
yielding ability in northern production areas. Fruit
yields are affected by the N/P balance. Greatest yields
were obtained with either low levels of both N and P or
high levels of both N and P (21). The N/P balance may
also affect the root/shoot ratio of tomato seedlings. The
root/shoot ratio plays an important role in maintaining a
balance between vegetative growth and fruiting of the plant
so large fruit yields are produced early in the picking
season (18).

These studies were conducted to determine the effects

of N and P fertilization Of transplants on tomato development

113

and yield in the field.

Materials and Methods

 

A. An Evaluation of Different Levels of Nitrogen and
Phosphorus on the Early Growth of_Pik—Red Tomatoes

 

 

This experiment was conducted at the Plant Science
Greenhouses of Michigan State University, East Lansing,
Michigan. On March 29, 1981 pottingrmalhnncontaining one
part Sphagnum moss to one part vermiculite was prepared.
Esmigran (Mallinckrodt Chemical Co.),a long term source
of micronutrients such as Fe, Mn, Zn, Cu, B and Mo, was
added to the soil mix at a rate of 55.5 g/cu meter. Fe
chelate sequestrene (Ciba GeigY) was also added to the mix
at a rate of 27.8 g/cu meter, along with dolomitic lime-
stone at a rate of 3 kg/cu meter. Superphosphate (0—A6-

0) was added to the medium in3 rates: 15, 30, and 60 ppm
available phosphorus. A colorimetric soil test was
performed for verification. Twenty-seven TODD 100A planter
flats were filled with the media,9 each containing low,
medium and high P levels.

Pik-Red tomato seed was pregerminated for 72 hours and
suspended in Viterra II hydrogel before sowing. One seed
was placed in each root cell on March 30, 1981. When the
first true leaves emerged, 3 levels of soluble N (100, 200
and A00 ppm) were applied weekly. K280“ and KNO3 were

used to provide the desired levels of N and maintain a

11A

concentration of 1100 ppm potassium in each N treatment.
These levels of N and P were recommended by Wittwer and
Honma as being low, moderate and high levels of
available N and P for weekly application to greenhouse
tomatoes (58).

Each treatment consisted of 3 TODD 100A planter flats
treated with various levels of N and P. Each flat served
as a replication. The experiment was completely randomized
in a 3 by 3 factorial arrangement, with 3 levels of
available P (15, 30 and 60 ppm) and 3 levels of N (100, 200
and A00 ppm). The flats were placed on adjacent benches
in the greenhouse under fluorescent lighting of 1A hours/
day.

Growth analysis started 2 weeks after sowing on April
13, 198l,when first true leaves developed and samples
were taken every 7 days thereafter for 1 month. Eight
plants were sampled at random from each of the 27 flats
at each harvest. Height and leaf number were measured
individually for the 8 plants, while leaf area, shoot
dry weight, and root dry weight for each flat were taken as
the mean of the pooled results of the 8 seedlings sampled
for each flat. Relative growth rate (RGR) and net
assimilation rate (NAR) were calculated using the growth
analysis method discussed by Leopold and Kriedemann in

Plant Growth and Development (28). Dry weight root to

 

shoot ratios were calculated to determine if the N/P

115

balance affects the root/shoot ratio of Pik-Red tomato

seedlings. Data was analyzed by analysis of variance.

B. The Effect of Nitrogen and Phosphorus Nutrition and
Transplant Age on Development and Yield of Pik-Red
Tomatoes in the Field

 

 

 

Twelve TODD 100A planter flats were prepared as
described above, with A each containing each of the 3
available P levels (15, 30, and 60 ppm). Pik—Red tomatoes
were sown as described above into 1 flat of each P level
on April 22, April 29, May 6, and May 13. The 3 N
levels (100, 200, A00 ppm) were applied weekly to different
P levels to create the following 3 nutrient‘breatments: high N -
low P, moderate N - moderate P, low N - high P. Flats
were also seeded on A different dates to create a factor-
ial experiment consisting of 3 nutrient treatments at A
sowing dates. The plants were grown in the Plant Science
Greenhouse, as described above. The flats were arranged
at random on greenhouse benches.

Data on seedling growth was collected periodically
as soon as the first true leaves deve10ped. Four plants
were sampled at random from each flat. Height and leaf
number were measured individually for the A plants, while
leaf area, shoot dry weight, and root dry weight for each
treatment were taken as the mean of the pooled leaf area
and dry weight of the A seedlings sampled for each flat.

Data were analyzed by analysis of variance.

116

On May 30, 1981, the remaining tomato seedlings were
transplanted into the field. Roots of transplants were
dipped into soluble 20-20-20 starter fertilizer solution
at a rate of 3.9 m1 fertilizer per liter of H20. The
field was irrigated overhead after transplanting. Ferti-
lizer was applied to the planting field at a rate of 56
kg/ha N, 112 kg/ha P

and 112 kg/ha K 0. The plants

205 2
were sidedressed with 56 kg/ha N after the first fruit

set. Irrigation was applied as necessary. Fungicides and
insecticideswere applied when necessary to control foliar
diseases and insects.

The experiment was designed as a randomized complete
block with 3 replications. The treatments were arranged
factorially with A ages of tomato seedlings at transplanting
(3, A, 5 and 6 weekly) and 3 levels of fertility. Each
plot consisted of 28 plants in 2 rows of 1A plants each.
Rows were A feet apart, with 2 feet between plants in rows.

Two plants per plot were harvested every week for
3 weeks after planting for growth analysis. Plant height,
leaf number, leaf area and dry weight were measured.
Relative growth rate (RGR) and net assimilation rate (NAR)
were calculated using the growth analysis method described
previously. Information on plant height, fresh weight,
fruit number and fruit weight was collected for weeks 3

to 9 after transplanting. All results were analyzed by

analysis of variance.

117

As the fruit matured, yield was taken once each week
from 1A plants per plot. Tomatoes showing any red
coloration were harvested. Harvested tomatoes were graded
as large fruit (greater than 6.7 cm in diameter), small
fruit (less than 6.7 cm in diameter) and culls. Fruit
number and fresh weight were recorded. Tomato fruit
harvested during the first two weeks were considered early
yield.

All results were analyzed by analysis of variance.
Treatment sums of squares were partitioned into linear,

quadratic and cubic effects through trend analysis.

Results

A. An Evaluation of Different Levels of Nitrogen and
Phosphorus on the Early Growth of Pik—Red Tomatoes

 

 

Three weeks after seeding tomato,seedlings fertilized
with high levels of N had statistically greater height,
leaf area and shoot dry weight than seedlings treated
with low levels of N (Table 27). At this time there were
no significant differences in plant size or weight
associated with differences in P levels.

Significant differences were obtained among N treat-
ments for height, leaf area, shoot dry weight and root
dry weight of tomatoes A weeks after seeding (Table 28).

A high level of N resulted in up to 75% increases in

these parameters. Root dry weights were statistically

118

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120

different when different levels of P were applied. Use
of 60 ppm P resulted in increased root dry weights as
compared to 30 or 15 ppm P. A significant N x P inter-
action was obtained for shoot dry weight. Use of a

high level of N and a moderate level of P resulted in the
greatest tomato shoot dry weight.

Five and 6 weeks after seeding,significant differences
were observed in plant height, leaf area, shoot dry weight
and root dry weight of seedling tomatoes fertilized with
different levels of N (Tables 29 and 30). Application of
A00 ppm N resulted in increased height, leaf area, shoot
dry weight and root dry weight. Five weeks after seeding
60 ppm P resulted in significantly increased plant height.
Six weeks after seeding,a significant interaction between
N and P levels was noted for leaf area. In this case,

a high or low level of P and a high level of N resulted
in greater leaf area than a moderate level of P and high
level of N. Significant differences in plant height,
leaf area and shoot dry weight occurred with increasing
levels of P fertilization. However, the increases in
height, leaf area and shoot dry weight with the use of
increased rates of P were slight when compared with the
increased measurements obtained with the application of
high levels of N.

The greatest root to shoot ratios of tomato seedlings
were obtained throughout the experiment when a low to

moderate level of N was applied with a moderate to high

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123

level of P. The N/P balance affects the root/shoot ratio
of the Pik-Hed tomato seedlings. Hudson believes that
this ratio is critical in affecting the yield and
maturation of the tomato fruit (18).

Net assimilation rate (NAR) was never significantly
different between treatments at any of the different growth
periods throughout the experiment. However, relative
growth rate (RGR)<1fthoseseedlings grown at high levels
of N was significantly greater than that of seedlings
grown at low levels of N from 3 to 5 weeks after seeding.
Tomato seedlings that received MOO ppm N grew more rapidly
for the first 5 weeks than those seedlings that received
either 200 or 100 ppm N.

NAR increased for seedlings of all treatments from
15 to 20 days after seeding, decreased and then remained
fairly constant from 25 to 30 days after sowing and
reached a minimum level from 30 to 35 days after sowing
(Figure l“). The phososynthetic efficiency of the
tomato seedlings from all nutrient treatments was greatest
when seedlings were 3 weeks old and then decreased to a
minimum level of efficiency at 5 to 6 weeks of age. The
RGR of all treatments also reached a maximum level at
3 weeks, and then decreased to a constant level at 3 l/2
to U l/2 weeks and decreased still further at 5 to 6 weeks
after seeding. The tomato seedlings of all treatments

were growing most rapidly at 3 weeks of age, when

12a

Figure 1M. The influence of days after sowing on the
mean relative growth rate (RGR) and net
assimilation rate (NAR) of Pik-Red
tomato plants of all nutrient treatments.

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126
photosynthetic efficiency was also greatest. Seedlings

of all treatments grew less rapidly from U to 6 weeks of

age, when photosynthetic efficiency decreased.

B. The Effect of Nitrogen and Phosphorus Nutrition_and
Transplant Age on Development and Yield of Tomatoes
in the Field

 

 

 

Growth of Pik-Red tomato seedlings, planted at different
dates and fertilized with different levels of N and P, was
monitored in the greenhouse and in the field.

Older tomato seedlings were taller than younger tomato
seedlings for the duration of the greenhouse experiment
(Table 31). Older seedlings also possessed greater leaf
area and shoot dry weight than did the younger tomatoes.

At field—setting, 6-week-old transplants were at least twice
as tall and possessed 7 times as much leaf area and shoot
dry weight as 3-week—old tomato seedlings.

Fertilizer treatments also influenced seedling growth
before transplanting (Table 31). Those seedlings fertilized
with high N and low P were taller and had greater leaf
area and shoot dry weight than those seedlings fertilized
with low N and high P. At transplanting, 3-week-old
seedlings fertilized with low N levels were smallest. An
interaction between plant age and nutrient level was
significant for transplant height. Plant height was
greatest in tomatoes of 6 weeks of age fertilized with high
N. The interaction was significant because 3—week-old plants
treated with moderate levels of N were taller than 3—week-old

plants treated with high levels of N.

127

Table 31. The influence of different levels of nitrogen
and phosphorus and plant age on the growth
of Pik-Red tomatoes at transplanting.

 

 

 

 

 

Shoot
. w x x
Height Leaf area dry weight
Treatment (cm) (59 cm) (g)
Age at Transplantingy
6 weeks 20.9 50.1 0.A0
5 weeks 20.5 “8.7 0.31
u weeks 15.7 20.7 0.15
3 weeks 8.0 7.0 0.05
Main effect ** ** **
Nutrient Level2
High N—Low P 18.3 40.0 0.25
Moderate N—Moderate
P 17.0 35.1 0.25
Low N-High P 13.5 20.7 0.20
Main effect ** ** *
Planting Date x
Nutrient Level ** NS NS

 

 

wHeight measurements are the means of N replications.

XLeaf area and shoot dry weight measurements represent the
mean of the pooled leaf area and shoot dry weight of u
seedlings sampled per treatment.

yAge at transplanting from 6 weeks to 3 weeks corresponds
to the date of seeding of TODD planter flats on April 22,
April 29, May 6 and May 13, 1981, respectively.

zNitrogen levels from high to low refer to the weekly

application of 400, 200 and 100 ppm nitrogen, respectively;
while phosphorus levels from high to low refer to the media
incorporation of 60, 30 and 15 ppm phosphorus, respectively.

* **
’ Significant at the 5 and 1% levels, respectively.

128

Three weeks after transplanting, significant differ—
ences in height, leaf number, leaf area and shoot dry
weight were observed with transplants of different ages
(Table 32). Plants that were A, 5 and 6 weeks old at
field-setting were larger than 3-week-old transplants.
Those treatments fertilized with moderate levels of N and
P were significantly greater in height and leaf area than
were plants of other nutrient treatments. There was a
significant interaction between planting date and nutrient
level for leaf area. The 5-week-old tomato plants treated
with a moderate level of N generally produced greater
leaf area, while 6-week—old transplants treated with a
high level of N produced a smaller amount of foliage.

There were no significant differences in RGR or NAR
between any treatments 3 weeks after transplanting.

Five weeks after field-setting, plants that were 3
weeks old at transplanting were shorter, possessed fewer
flowers setting fruit and less dry weight than the older
plants, which were similar in size (Table 33). There
were no differences in these measurements as a result
of different nutrient treatments. There were significant
interactions between planting date and nutrient level
for shoot dry weight and number of flowers setting
fruit. Plants A weeks old at field setting and treated

with a high level of N produced the greatest number of

129

Table 32. The influence of different levels of nitrogen
and phosphorus and plant age on the growth
of Pik-Red tomatoes 3 weeks after transplanting.

 

 

 

 

 

Shoot
HeightX Leaf areaX dry weightX
Treatment (cm) (sg cm) (g)
Age at Transplantingy
6 weeks 3“.” 23M.6 2.67
5 weeks 37.5 23U.6 2.57
U weeks 33.5 236.7 2.26
3 weeks 26.5 152.6 1.55
Main effect ** ** **
Nutrient Levelz
High N-Low P 31.6 195.1 2.03
Moderate N—Moderate
P 35.8 2A3.6 2.50
Low N-High P 31.u 203.2 2.26
Main effect ** ** NS
Planting Date x
Nutrient Level NS ** NS

 

 

XFigures are the means of 2 plants harvested per 3 replica-
tions on June 17, 1981.

yAge at transplanting from 6 weeks to 3 weeks corresponds
to the date of seeding of TODD planter flats on April 22,
April 29, May 6 and May 13, 1981, respectively.

ZNitrogen levels from high to low refer to the weekly
application of 400, 200 and 100 ppm nitrogen, respectively,
while phosphorus levels from high to low refer to the media
incorporation of 60, 30 and 15 ppm phosphorus, respectively.

* xx
’ Significant at the 5 and 1% levels, respectively.

130

Table 33. The influence of different levels of nitrogen
and phosphorus and plant age on the growth
of Pik-Red tomatoes 5 weeks after transplanting.

 

 

 

 

 

Number of Shoot
HeightX flowers dry weightX
Treatment (cm) setting fruit (g)
Age at Transplantingy
6 weeks 65.7 4 46.9
5 weeks 63.4 6 48.4
4 weeks 64.3 7 47.2
3 weeks 60.1 2 41.1
Main effect * ** *
Nutrient Level2
High N—Low P 64.6 5 46.1
Moderate N-Moderate
P 62.3 4 45.8
Low N-High P 63.2 5 45.8
Main effect NS NS NS
Planting Date x
Nutrient Level NS * *

 

 

XFigures are the means of 2 plants harvested per 3 replica-

tions on July 2, 1981.

yAge at transplanting from 6 weeks to 3 weeks corresponds
to the date of seeding of TODD planter flats on April 22,
April 29, May 6 and May 13, 1981, respectively.

zNitrogen levels from high to low refer to the weekly

application of 400, 200
while phosphorus levels
incorporation of 60, 30

x **
’ Significant at the 5

and 100 ppm nitrogen, respectively;
from high to low refer to the media
and 15 ppm phosphorus, respectively.

and 1% levels, respectively.

131

flowers setting fruit. Plants 6 weeks old at transplanting
and fertilized with a moderate level of N produced the
greatest shoot dry weight.

At 7 weeks after transplanting, plant height and
fruit weight were significantly greater for transplants
4 and 5 weeks of age compared to transplants of 3 and 6
weeks of age (Table 34). Increased height was also
observed with the high N-low P treatment.

There were no significant differences between any
nutrient or plant age treatments for fruit weight 9 weeks
after field setting. Plants of all treatments were of a
similar size 9 weeks after transplanting.

Although tomato plants of all treatments were of a
similar size 9 weeks after transplanting, there were large
differences in early yields (Table 35, Figure 15). With
increasing plant age, total early yields increased in a
linear and quadratic manner, while large fruit early yield
increased in a quadratic manner. This is reflected in
the finding that plants of 4 and 5 weeks of age out-yielded
plants of 3 and 6 weeks of age at transplanting. Plants
set in the field at 4 and 5 weeks of age produced double
the large fruit early yield and up to 60% increases in
total early yield over plants set in the field at 3 or 6
weeks of age.

The level of N and P applied before field-setting also

132

Table 34. The influence of different levels of nitrogen
and phosphorus and plant age on the growth
of Pik—Red tomatoes 7 weeks after transplanting.

 

 

 

 

 

Total Shoot
Number of fruit dry
HeightX flowers weightX weightX
Treatment (cm) setting fruitX (g) (g)
Age at Transplanting
6 weeks 81.5 7 145.0 95.8
5 weeks 83.6 9 196.9 98.1
4 weeks 79.9 8 217.8 88.3
3 weeks 76.3 6 72.8 79.2
Main effect ** NS ** NS
Nutrient LevelZ
High N—Low P 82.8 8 189.4 94.6
Moderate N—

Moderate P 80.9 7 159.4 86.5
Low H—High P 77.3 7 125.6 90.0
Main effect ** NS NS NS

Planting Date x
Nutrient Level NS NS NS NS

 

 

XFigures are the means of 2 plants harvested per 3
replications on July 15, 1981.

yAge at transplanting from 6 weeks to 3 weeks corresponds
to the date of seeding of TODD planter flats on April 22,
April 29, May 6, and May 13, 1981, respectively.

zNitrogen levels from high to low refer to the weekly

application of 400, 200
while phosphorus levels
incorporation of 60, 30

**

x
’ Significant at the 5

and 100 ppm nitrogen, respectively;
frdm high to low refer to the media
and 15 ppm phosphorus, respectively.

and 1% levels, respectively.

133

 

 

 

 

Table 35. The influence of different levels of nitrogen
and phosphorus and plant age on the early yield
of Pik—Red tomatoes in 1981.
Total Large fruit
early yieldX early yieldX
Treatment (kg/ha) (kg/ha)
Age at Transplantingy
6 weeks 11593 8599
5 weeks 15439 11273
4 weeks 15507 11452
3 weeks 9287 6588
linear * NS
quadratic ** **
Nutrient LevelsZ
High N Low P 14788 11024
Moderate N-Moderate P 13164 10093
Low N-High P 10918 7318
linear ** **
quadratic NS NS

 

xTomatoes were harvested from 14 plants per plot. Yield
measurements are means of 3 replications. Early season
yields were harvested during the first 2 weeks of the
harvest season on August 13 and August 20. Large fruit
yield refers to the weight of marketable fruit harvested
greater than 6.7 cm in diameter. Fruit weight was
converted to kilograms/hectare.

yThe tomato seeds were sown at 4 different dates; April 22,

April 29, May 6 and May 13, 1981, so that seedlings were
6, 5, 4 and 3 weeks of age at transplanting.

ZThree different levels of nitrogen and phosphorus were
applied to the seedlings as fertilizer treatments before
field setting.

* **
’ Significant at the 5 and 1% levels, respectively.

134

Figure 15. The influence of different levels of nitrogen
and phosphorus before field-setting and trans-
plant age at field-setting on the early yield
of Pik—Hed tomatoes.

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had an effect on early yields (Table 35, Figure 15). As
levels of N increased and levels of P decreased in the
fertilizer before field-setting, total and large fruit
early yields also increased in a linear manner. The high
N and low P treatment produced the greatest early yields,
indicating that 400 ppm N and 14 ppm P applied together
before transplanting were important in increasing tomato
fruit productions 11 weeks after field setting.

Although 4- and 5-week-old transplants produced greater
early yields, 3- and 6-week-old transplants produced larger
yields later in the season. Four-and 5-week-old tomato
transplants dropped in production at midseason, so that
significant differences in late season yields were detected.
Four and 5-week-old tomato transplants matured approxi-
mately 1 to 2 weeks earlier than 3- or 5-week-old trans-
plants.

No significant differences in small fruit number or
weight or cull fruit number or weight were found among
treatments at any of the 4 harvest periods. However, total
small fruit yield and total fruit yield increased in a
linear fashion with increasing plant age. Six-week-old
transplants produced the greatest total small yields and
total yields (Table 36, Figure 16). The level of N and
P applied totransplants before field-setting had little
effect on total yield of Pik-Red tomatoes. No significant
differences were observed in total fruit number or total

fruit weight among the nutrient treatments.

137

 

 

 

 

 

Table 36. The influence of different levels of nitrogen
and phosphorus and plant age on the total
yield of Pik—Red tomatoes in 1981.
Total Total Total
large small cull Total
yieldtx yieldtw yieldtv yieldtu
Treatment (kg/ha) (kg/ha) (kg/ha) (kg/ha)
Age at Transplantingy
6 weeks 86459 11423 14083 111965
5 weeks 85892 9418 15042 110352
4 weeks 80137 9374 13647 103114
3 weeks 80355 7574 14432 102460
linear NS ** NS *
quadratic NS NS NS NS
Nutrient LevelsZ
High N-Low P 83897 9854 15325 109055
Moderate N-
Moderate P 86339 9472 13036 108858
Low N—High P 79385 9112 14552 102983
linear NS NS NS NS
quadratic NS NS NS NS
tYield measurements are means of 3 replications. Fruit

weight was converted to kilograms/hectare.

uTotal fruit yield is the total yield of all fruit harvested

during the season.

VCull yield refers to the weight of non-marketable fruit

harvested.

wSmall fruit yield refers to the weight of marketable fruit

harvested less than 6.7 cm in diameter.

XLarge fruit yield refers to the weight of marketable fruit
harvested greater than 6.7 cm in diameter.

yT

he tomato seeds were sown at 4 different dates; April 22,

April 29, May 6 and May 13, 1981; so that seedlings were
6, 5, 4 and 3 weeks of age at transplanting.

ZThree different levels of nitrogen and phosphorus were
applied to the seedlings as fertilizer treatments before

field setting.
* **

’ Significant at the 5 and 1% levels, respectively.

138

Figure 16. The influence of different levels of nitrogen
and phosphorus before field-setting and

transplant age at field-setting on the total
yield of Pik—Red tomatoes.

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140

Discussion and Conclusions

 

The levels of N and P fertilizer applied to tomato trans-
plants before field-setting significantly affected seedling
growth and development both before and after transplanting
into the field. High levels of N produced increases in
tomato seedling height, leaf area and shoot dry weight.
Moderate to high levels of P produced slight increases in
seedling height, leaf area, shoot dry weight and root dry
weight. Wilcox and Langston reported that N was the most
limiting element to tomato seedling growth in an experiment
using a soluble nutrient solution. A small increase in
seedling growth was also observed with increased P levels
(57). Although the availability of P has been reported
to be most critical in increasing the tomatoes' growth
rate and yielding ability (7, 23, 36, 41, 56, 57), Wilcox
and Langston believe that the optimum soil temperature in
the greenhouse resulting in increased availability of
phosphorus and the age and condition of the tomato seed-
lings accounts for the lack of great response of tomato
seedlings produced in the greenhouse to high levels of P
fertilizer (57)-

High levels of N also promoted significant increases

in the relative growth rate of seedling tomatoes. This

141

was not unexpected since researchers have shown that N
strongly affects seedling growth rate by promoting rapid
growth (33, 57).

Several significant interactions occurred between N
levels and P levels for plant height, leaf area and shoot
dry weightin the first nutrient experiment. In most cases,
the interaction was significant because a high level of
N and a moderate level of P promoted the largest increases
in plant height, leaf area and shoot dry weight. Jaworski
and Webb found that the balance of N to P is a very
important factor influencing tomato growth and yielding
ability (21). In this case, the optimal level of ferti-
lization for the production of the largest tomato trans-
plants was 400 ppm N and 30 ppm P.

Tomato seedlings from all nutrient treatments exhibited
the greatest net assimilation rate and relative growth
rate at 3 weeks of age and the lowest RGR and NAR at 6
weeks of age. The embryo of a plant begins to grow in
an exponential manner and photosynthetic efficiency will
determine the rate of growth (28). Until 3 weeks of age,
seedling growth was still increasing and NAR and RGR were
greatest at this point. After 3 weeks of age, it appears
that interactions with the environment began to impose
limitations and seedling growth slowed as RGR and NAR
decreased.

The root to shoot ratio of tomato seedlings was only

142

slightly altered by nutrient treatments. The greatest
root to shoot ratio was observed with a low to moderate
level of N and a moderate to high level of P. Low

levels of N decrease shoot development and high levels

of P are known to stimulate root production (33, 52, 53,
54). Hudson (18) and Leonard and Head (27) have
emphasized the importance of root-shoot balance in tomato
fruit production.

In the field experiment, tomato seedlings were
produced at 3 levels of N and 3 levels of P. Treatments
were designed to alter the root to shoot ratios of the
seedlings in an effort to produce a transplant with a large,
quickly growing initial root system. As before, those
seedlings fertilized with a high level of N and a low level
of P were larger than those seedlings fertilized with a
low level of N and a high level of P at transplanting. A
high level of N and a low level P before transplanting
resulted in increased plant height and number of flowers
setting fruit after transplanting, while a moderate level
of N and P resulted in increased leaf area after trans-
planting. Nutrient treatments affected plant growth less
in the field than did plant age at transplanting.
Apparently, the tomato seedlings of all nutrient treatments
were able to utilize the available nutrients in the field
to overcome any initial differences in plant size created

by preplant nutrient treatments by the time of the first

143

fruit ripening.

Although plant size was similar, at first fruit
ripening early yielding abilities of the plants fertilized
with different starter nutrient treatments were varied.
Tomato transplants fertilized with high levels of N and
low levels of P produced greater early yields than trans-
plants fertilized with low levels of N and high levels
of P,even though plant size was similar. Early yields
increased in a linear manner with increasing N and
decreasing P. Transplants fertilized with high N and low
P were significantly larger in size at transplanting.
Wilcox and Langston found that transplanted tomatoes
responded more to N starter fertilizer than to P starter
fertilizer when transplanted into the field. Increased
N before transplanting resulted in larger tomato plants
exhibiting earlier maturity (57). Jaworski also found
that moderate levels of N were necessary to produce large
marketable yields and uniform development of transplanted
tomatoes (19).

The tomato transplant carries a potential nutrient
reserve to be drawn upon during the re-establishment of its
root system (57). Apparently, increased N applied before
field-setting produced a larger seedling with a greater
N reserve, resulting in earlier maturity and larger early
yields. By midseason, plant maturity and yielding

abilities of plants from all nutrient treatments were similar.

144

The role of applied P in the development of trans—
planted tomatoes may have been minor because field soil
temperatures were warm and transplants from all treatments
possessed an intact root system at the time of planting,
which was able to forage for sufficient levels of P.
Apparently, P was not a limiting factor in transplant
growth and development. Under these conditions, plants
with a lower root/shoot ratio produced greater early yields.

Transplant age significantly affected seedling size
at transplanting. Six-week—old tomato seedlings were larger
in size than either 3, 4 or 5 week-old tomato seedlings,
most likely because of a longer growth period. However,

3 to 5 weeks after transplanting into the field, plants

of 4 and 5 weeks of age caught up in size and produced a
greater number of flowers setting fruit and shoot dry weight
than other treatments. Significant interactions between
planting date and nutrient level for shoot dry weight and
number of flowers setting fruit occurred as plants of 4

and 5 weeks of age from all nutrient treatments produced
greater measurements than plants of 3 and 6 weeks of age.

The age of the transplant at field-setting was very
important in determining early yielding ability of tomato
transplants. Four.and 5-week-old plants produced the
greatest early yields while 3- and 6-week-old plants
produced larger late and slightly larger total yields.

Skapski and Lipinski found that very young and small

145

transplants of 3 to 4 weeks of age produced lower yields
than older transplants, particularly during adverse weather
conditions (45). Three-week-old plants were very small
and immature at transplanting, which may account for their
delayed maturity and lower early yields. Transplants of
4 and 5 weeks of age were able to recover more quickly
after transplanting than other age treatments probably
because they were of adequate size and were not yet root
bound. Casseres found that transplants which were tender
and capable of quick recovery after transplanting produced
larger early yields (12). Nicklow and Minges reported
that a relatively small 3- to 5-week—old tomato transplant
without flowers or buds produced the largest fruit and
larger overall yields. Older plants which were over-
hardened or were in flower were not desirable (37). Six-
week-old plants may have been overhardened or slightly
root-bound at transplanting which resulted in greater
transplant shock and slightly delayed plant maturity,
causing lower early yields.

Midseason yields were similar for all transplant treat-
ments. However, 3- and 6-week—old transplants produced
the largest late season yields. These transplants
exhibited delayed maturity and produced a greater percentage
of ripe fruit later in the season. Total yields were
fairly similar for all plant ages and nutrient treatments.

Cultural practices applied before field-setting such as

146

fertilizers and date of sowing were short-lived in their

effects on the yielding ability of tomato transplants.

147

SUMMARY

SUMMARY

In conclusion, the use of larger sizes of TODD root
cells resulted in larger early yields and total marketable
yields in fresh market tomatoes and peppers. A high level
of N and a low level of P applied to tomato transplants
in TODD flats before field-setting resulted in larger
transplant size and greater early yields. The use of tomato
transplants 4- to 5-weeks-old at field-setting resulted
in larger early yields. Tomato transplants grown in
Michigan produced larger early yields and slightly larger
total marketable yields than transplants produced by
Speedling of Florida and shipped north. Hardening trans-
plants by withholding major nutrients may have been
responsible for decreased early yields of Speedling trans-
plants. Packaging and shipping of plants from Florida to
Michigan by air freight appeared to have no stressful
effects on Speedling plants, as measured by ethylene and
C02 production.

On the basis of this work, the best method of obtaining
large early yields for fresh market tomato and pepper
production involves the following: the use of size 175
TODD planter flats, the weekly application of high level
of N fertilizer (400 ppm) and a low level of P fertilizer

148

149
(15 ppm) to tomatoes, and the transplanting of tomato
seedlings at 4 to 5 weeks of age.

The most cost-effective method of obtaining large
total yields for fresh market tomato and pepper production
involves the following: the use of smaller sizes of TODD
planter flats, the weekly application of a high level of
N (400 ppm) and a low level of P (15 ppm) to tomatoes,
and the transplanting of tomatoes when seedlings are 4

weeks of age.

150

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