NW0 8 2000

FACTORS AND PRACTICES RELATED TO THE OCCURRENCE
OF BLOTCHY RIPENING IN TOMATO

BY

.“

James w; Berry, Jr.

AN ABSTRACT OF A THESIS

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

DOCTOR OF PHILOSOPHY
Department of Horticulture

1966

ABSTRACT

FACTORS AND PRACTICES RELATED TO THE OCCURRENCE
OF BLOTCHY RIPENING IN TOMATO

By James w. Berry, Jr.

Blotchy ripening, characterized by greenish-yellow
areas on otherwise ripe tomato fruit, has been a serious
problem during certain growing seasons. A lack of balance
in soil nutrient levels, adverse weather conditions, viral
infections or a combination of one or more of these factors
have been suspected causes of blotchy ripening. The primary
objective of this study was to evaluate the role of different
moisture stresses upon the incidence of blotchy ripening.

The influence of different soil moisture levels in
combination with several transpiration influencing practices
upon the incidence of blotchy ripening were evaluated at the
Horticulture farm in East Lansing during 1962 through 1964.
Treatments used to influence transpiration were phenylmer-
curic acetate, glycerol, copper sulfate, octa-hexadecanol,
misting with water, reducing air movement with various
enclosures, and infra-red heat lamps. Phenylmercuric ace-
tate, a chemical reported to close stomates, was the only
chemical used to influence transpiration in both greenhouse
and field studies. The other chemicals were used only in a
greenhouse study. Fireball and Glamour were the principal

tomato varieties used.

James W. Berry - 2

The over-all moisture stress to which tomato plants
are subjected appears to influence the quality of fruit as
measured by percent dry matter. soluble solids, and color
uniformity. Data collected in these studies suggest that
blotchy ripening and blossom end rot are caused by opposite
moisture stress conditions, blotchy ripening appearing more
frequently under conditions of low moisture stress and
blossom end rot being more prevalent under high.moisture
stress conditions.

Seed density beneath blotchy and normal tissue was
determined. Low locular seed incidence within a fruit was
associated with blotchy tissue; a reduced source of auxin
was postulated as possibly contributing to the disorder.

The placement of pollen on one side of the stigma,
or the removal of a section of stigma and style at the time
of pollination influenced the incidence of blotchy ripening.
Poor pollination may play a role in the incidence of blotchy
ripening by reducing the number of seed in some locules.

An interplay of both poor pollination and the
occurence of adverse weather conditions to produce blotchy

ripening is suggested.

FACTORS AND PRACTICES RELATED TO THE OCCURRENCE
OF BLOTCHY RIPENING IN TOMATO

By

)‘ V~\

James w:\Berry, Jr.

A THESIS

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

DOCTOR OF PHILOSOPHY

Department of Horticulture

1966

ACKNOWLEDGEMENT

The author wishes to thank Dr. Robert L. Carolus for
his help and advice in conducting the experiments and
preparation of the manuscript. Appreciation is also expressed
to Dr. J. B. Beard, Dr. H. C. Beeskow, Dr. S. K. Bias. and
Dr. S. H.'wittwer for their advice and guidance during the
course of this investigation and to Dr. Kenworthy for his
help in analyzing fruit and foliage tissue for nutrient con-
tent.

Gratitude is expressed to Michigan State University
for providing a research assistantship, without which this
work would not have been completed.

The author wishes to express appreciation to his wife.

Janene, for her assistance and encouragement.

11

CONTENTS

Page

INTRODUCTION 0 O O O O 0 O O O O O O O 0 O O O O O O O 1
REVIE“ OF LITERATURE O 0 O O O O O O O O 0 O O O O O O 3
Term1n01°gy O O I O O 0 O O O O O O O O 0 O O O O 3
Nutritional Aspects . . . . . . . . . . . . . . . 5
Environmental Factors . . . . . . . . . . . . . . 8
Tobacco Mosaic Infection . . . . . . . . . . . . . 13
comm81 tion 0 O O O C O O O O O O O O O O O O O O 17

FIELD EXPERIMENTATION . . . . . . . . . . . . . . . . 21
Effect of Soil Moisture Level and Shade on

Blotchy Ripening (1962) .~. . . . . 21
Effect of various Treatments on the Incidence of

Blotchy Ripening . . . . . . 28
Environmental Influences on Blotchy Ripening

(1963).. . . . . . . 31

The Influence of Locular Seed Density on the

Localization of Blotchy Ripening . . . . . . . . 53

Influence of uneven Pollination on the Incidence

Of Blotchy Bipenim O O 0 O O O O O O O O O O O O 59
EFFECT OF CERTAIN CHEMICALS 0N TBANSPIRATION . . . . . 65

INFLUENCE OF VARIOUS MOISTURE STRESSES ON THE
INCIDENCE OF BLOTCHY RIPENING . . . . . . . . . . . . 68

GENERALIDISCUSSION AND CONCLUSIONS . . . . . . . . . . 89
LITERATURE CITED 0 e e e e e e e e e e o e e e e e o e 9""

iii

Table

10

ll

12

13

LIST OF TABLES

The influence of shade and high soil moisture
on blotchy ripening . . . . . . . . . . . . . .

variation in percent soluble solids of tomato
fruit 0 O O O O O O I O O O I O O O O O O O O O

The influence of various treatments on fruit
size. yield. and the percentage of blotchy
ripening O O O O O O O O O O O O O O O 0 O O O

The effect of variety and treatment on average
fruit Size 0 O O O O O O O O O O O O O O O O O

The effect of treatments on the percent
soluble solids of normal and blotchy fruit of
Fireball tomatoes . . . . . . . . . . . . . . .

The influence of windbreaks upon temperature .

The influence of windbreaks upon relative
humidity O O O O O O O O 0 O O O O O O O O O O

The effects of treatments designed to modify
moisture and carbohydrate stresses on the
number and weight of fruit produced per plant .

Relationship of fruit size to blotchy ripening

Mean percent soluble solids of Fireball and
Glamour tomatoes classed as normal and
blotcm C O O O O O O O O O O O O O O O O O O 0

Average percent soluble solids of normal and
blotchy tissue from tomato fruits of the
varieties Fireball and Glamour . . . . . . . .

The influence of various practices, treatments.
and soil moisture levels on percent soluble
solids of tomato fruit . . . . . . . . . . . .

The influence of various practices. treatments,

and soil moisture upon the average rate of
increase of Fireball tomato fruit diameter . .

iv

Page

25

26

30

3.2

33
39

39

no
42

42

‘43

1+4

46

Table
in

15

l6

17

18

19

20

21

Page

The influence of various treatments and soil
moisture levels upon the average rate of
increase of Glamour tomato fruit diameter . . . 47

Relation of seed per unit area in blotchy and
non-blotchy areas of the same fruit. Field
1963 O O O O O O O O O O O O O O O O I O O O O 55

The influence of various methods to induce
uneven and/or poor pollination upon the
incidence of blotchy ripening . . . . . . . . . 61

water use by tomatoes as related to irrigation
and treatment 0 O O O O O O 0 0 O O O O O O O O 71

The influence of moisture stress upon fruit

number. fruit weight. average fruit weight,

soluble solids, dry weight of fruit. and

foliage tissues of tomato varieties Fireball

and Glamour . . . . . . . . . . . . . . . . . . 73

The influence of moisture stress upon the

number and weight per plant of blotchy fruit,

normal fruit, and fruit affected with blossom-

end rot from the tomato varieties Fireball

and Glamour . . . . . . . . . . . . . . . . . . 75

The influence of moisture stress upon the

amount of minerals accumulated in the fruit

and foliage tissue of Fireball and Glamour

tomato plants . . . . . . . . . . . . . . . . . 79

The influence of moisture stress upon the

amount of minerals accumulated in the fruit

and foliage tissue of Fireball and Glamour

tomato plants . . . . . . . . . . . . . . . . . 80

Figure

LIST OF FIGURES

Page

Tomato fruit showing outer wall tissue
affected with localized blotchy ripening . . . 2

Cross section of tomato fruit indicating
relationship between low seed density and

incidence of blotchy tissue. Areas designated

(n) normal contained from 22-62 seed per

locule. those designated (b) blotchy. contained

less than 22 seeds per locule . . . . . . . . 56

The influence of glycerol, copper sulfate, and
octa-hexadecanol on transpiration rates of
tomato Plants. 1962 e e e e e e e e e e e e e 67

Relationship between fruit weight and soluble
solids for the variety Fireball . . . . . . . 78

INTRODUCTION

Blotchy ripening of tomato fruit is characterized by
outer wall tissue that usually remains greenish-yellow in
color after the fruit has turned red (Fig. 1).

This ripening disorder of tomato fruits occurs sporadi-
cally in field and greenhouse grown tomatoes and affects a
considerable percentage of the fruits during some growing
seasons. but is almost nonexistant in others. The blotchy
areas have been reported to occur anywhere on the fruit, but
generally appear on the shoulders or midsection rather than
on the blossom-end.

NUmerous suggestions concerning the cause and control
of blotchy ripening have been proposed. Hypotheses as to
causation are generally related to a lack of balance in soil
nutrient levels, weather conditions, viral infections, or a
combination of one or more of these factors.

Because of the unevenly scattered outbreaks of blotchy
ripening. and from a survey of the literature. it was sus-
pected that climatic factors affecting the water balance of
tomato plants play a dominant role in development of the
disorder. .

The primary objective of this study was to evaluate
the role of different moisture stresses imposed upon tomato
plants and their influence upon the incidence of blotchy
ripening.

 

 

Fig. l.

 

Tomato fruit showing outer wall tissue affected
with localized blotchy ripening.

REVIEW OF LITERATURE

Egrginologz

The first description of blotchy ripening occurred
in a grading system introduced at the Experimental and
Research Station. Chesthunt. England. in 1921. and was
merely noted as grade E - blotchy fruit which ripen unevenly
(20).

Bewley and White (5. 6) modified the definition by
excluding fruits infected with virus, mosaic. and those hav-
ing a hard green area, "greenback”. around the stem-end.
They defined blotchy ripening as a disorder in which fruits
developed hard yellowishqgreen or clear glassy appearing
areas when the remainder of the fruit's surface appeared
normally colored. Brownish vascular tissue was usually asso-
ciated with the affected areas.

In 1933. Bewley. Read. and Orchard (7) again listed
the previously defined types of non-uniform colored fruit,
and defined an additional class distinct from true blotchy
ripening, which they termed "yellow mettle“.

Lnater Seaton and Gray (98), in the united States,
defined blotchy ripening as a disorder in which areas of the
fruit remained hard and green. The position of the green
areas was not included in the definition as it had been by
Bewley and White. Seaton and Gray were of the opinion that

u

the clear glassy areas were merely a later stage in the
ripening of the green areas rather than a more severe case
of blotchy ripening.

In New Zealand blotchy ripening was referred to by
the name ”cloud” by Kidson and Stanton (59). It was defined
as a disorder in which ripe fruit showed green or brownish-
green areas with underlying brown veins appearing anywhere
on the fruit. They stated that the areas may eventually
become yellowish-red or even red. They did not include
fruits showing unpigmented glassy areas. Kidson and Stanton
(59) noted that the disorder ”cloud“ was similar in.appear-
ance to ”vascular browning" observed by Conover (19) in
Florida. Conover described ”vascular browning" as a grayish
brown discoloration seen through the somewhat translucent
outer wall and is similar to that outlined by Bewley and
White (6) for severe cases of blotchy ripening. Conover
stated that placental and septa tissues were not affected.

Raenseler (43) described a disorder similar to “vas-
cular browning" in New Jersey. He noted that the affected
fruits were usually somewhat abnormal in color. generally
being yellowish. Affected fruits also showed dark translu-
cent areas with indistinct limits near the stem end. The
disorder Haenseler described differed from that of Conover's
in that the septa and fleshy inner partitions of the fruit
were severely browned in advance cases. Raenseler termed

the disorder “internal browning”.

5
Stoner and Hogan (10?) used the term "graywall” to

describe a disorder resembling blotchy ripening. For the
most part their description of ”graywall' agrees with Cono-
ver's description of ”vascular browning“.' Lorenz and Knott
(72) noted that affected fruit often show a relatively thin
wall or pericarp on the side most exposed to the sun and
suggested that the term "thindwall' might be used to replace
the term "graywa11”.

Cooper (21. 2#) concluded that there are four color
disorders included under the term blotchy ripening, each
possibly with a different cause: 1. greenback. in which an
area of the fruit around the calyx remains green when the
rest of the fruit is red. with rarely any brown discoloration
of the internal tissue: 2. green-blotch in which any area of
the fruit may remain green when the fruit is red, vascular
browning is usually. but not always. present: 3. yellow or
unpigmented-blotch in which vascular browning may or may not
occur, and which may or may not be visible as a bronzed dis-
coloration in the immature green fruit; u. bronzing in which
ripe fruit show symptoms similar to yellow-blotch in the

presence of tobacco mosaic virus.

Nutritional Aspects

Bewley and White (6) indicated that nutritional fac-
tors controlled blotchy ripening. They found an inverse
relationship between the percentage of blotchy tomatoes and

6

the increments of nitrogen and potash, particularly potash,
added to the soil of plots deficient in these nutrients.
They also implied that climatic factors could be involved
because some fruits became blotchy even when plots were well
fertilized.

Work on "cloud" in New Zealand by Kidson and Stanton
(59) showed that the application of glucose to the soil and
frequent watering increased the incidence of the disorder
while applications of nitrogen and potassium tended to
counteract it. and applications of calcium chloride almost
completely prevented it. Kidson and Stanton concluded that
a virus was not likely to be involved because of the fre-
quency with which “cloud" was induced by greenhouse manage-
ment. Temperature and rainy weather were also indicated as
possible factors influencing the incidence of the disorder.

Hinsor, et al. (120). found that the proportion of
irregularly colored fruit could be reduced by adjusting the
potash/nitrogen ratio to between 2.0 and 2.5. With applica-
tions of 1600-1800 lbs. potash (K29) per acre they obtained
the smallest percentage of irregularly ripened fruit. Winsor
and others (121) working with different concentrations of
nutrients found that fruit quality improved up to a concen-
tration of 394 ppm K20 (potassium nitrate) and 225 ppm nitro-
gen (potassium nitrate and ammonium sulfate).

Stanton (106) found that. in general, fruit quality
improved with higher levels of nitrogen and potassium. Owen

7
(90). Iamm (71), and Stromme (108) also reported a marked

reduction in the proportion of blotchy fruit by increasing
levels of potash.

Kidson and Stanton (68) found that heavy applications
of superphosphate or lime increased the incidence of cloud;
however, these harmful effects were offset by liberal appli-
cations of nitrogen and potassium. Analyses of plant mater-
ial suggested a relation between cloud susceptibility and
the P/K ratio in the soil, but this relationship was not
apparent when plants were grown in water culture.

Clay and Endson (17) found that blotchy ripening could
be reduced by relatively heavy applications of a mixture of
potassium and magnesium sulfates. They attributed the reduc-
tion in blotchy ripening to increased soil salinity, and also
noted that blossom-end rot increased as soil salinity
increased. Fruit of best quality were produced on soil with
moderate levels of salinity.

In Florida it was found that the incidence and sever-
ity of blotchy ripening was higher when plants were grown in
nutrient cultures associated with low nutrient concentrations
and/or low nitrate/chloride ratios (39). Reports from the
Cawthron Institute (15. 16) also indicated that nutrient
levels markedly affected the incidence of cloud and observed
twelve times as much cloud at a low as at a high level of N
and K.

Working with tomatoes in water-cultures, Kidson (65,

8
66) found that an increased osmotic pressure of the nutrient
solution reduced the incidence of cloud. This was accom-
panied by a reduction of Ca and K in the leaves and more
than a 10-fold rise in Na. No relationship between blotchy
ripening and various levels of Brand Ca were found. The
application Cf Fe. N. or K did not affect the incidence of
cloud (62) whereas applications of zinc were associated with
an increase in the severity of cloud symptoms (63). It
appears that the quality of fruit color was not associated
with any one nutrient but to a general increase in soluble
salt concentration.

Butters (12. 13) used sodium sulphate in conjunction
with an adequate level of major nutrients to increase the
concentration of the soil solution. During the first year,
the treatment gave an improvement in uniformity of pigmenta-

tion. but was less effective during the following growing

8838011.

WM

With reference to Bewley and White's work (6). Seaton
(97). and Seaton and Gray (98) indicated that nutrient
deficiency was not the primary cause of blotchy ripening.
They advanced the hypothesis that the disorder is caused by
a sudden withdrawal of water from the fruit three to five
days before ripening, resulting in mechanical disruption of

the vascular system and prevention of translocation of

9
elaborated food materials. They based thisconclusion on
the morphological appearance of the vascular system in sec-
tions of affected fruit: but did not present any experimental
evidence to support their view. They suggested that deficien-
cies of potassium and nitrogen are probably secondary factors
with respect to the incidence of blotchy ripening.

Gignate (#0) also found that vascular bundles of
affected fruit appeared to be mechanically disrupted, and
that the epidermis of a ripened fruit was often underlain
with white spongy tissues. Gignate agreed with Seaton and
Gray in that the vascular disruption could occur under mois-
ture stress, and went further by outlining the environmental
conditions under which this could occur: if a dry spell
immediately follows a wet spell the fruit would experience a
rapid uptake of water followed by a rapid loss of water
through transpiration which would result in a stress on the
vascular system of the fruits.

white (110) noted that an increase in daylength.was
associated with a decrease in the percentage of blotchy fruit
despite an increase in over-all crop weight. Since these
conditions would result in a greater depletion of nutrients,
white suggested that blotchy ripening was not directly due to
potassium or nitrogen deficiency, but to metabolic changes
counteracted by increased light. Re attributed the bone-
ficial effect of increased light to increased carbohydrate
levels in the plant.

10

Lorenz and Knott (72) attribute the disorder they
called "graywall” or ”thin-wall” to uneven heating of fruits,
particularly those exposed to the sun. As the unshaded side
of the fruit warmed, the water was distilled from the warm
side to the shaded side of the fruit, thus, the young cells
on the unshaded side of the fruit would not be able to main-
tain a turgor satisfactory for normal cell functioning. The
uneven coloring disappeared as the fruit ripened.

Conover (19) found that “vascular browning” was most
severe in fruit from heavily shaded plants. He isolated no
causual organisms. Stoner and Hogan (10?) working with what
appeared to be the same disorder as reported by Conover,
concluded that the disorder was some physiological factor.
neither nutritional nor viral.

Haenseler (43) was unable to find a correlation
between internal browning. major nutrient levels. minor ele-
ment deficiencies or toxic materials in the soil. He
observed that fruits from only the second and third harvest
were seriously affected in that particular growing season
and that the trouble diminished as the season progressed.

Kidson and Stanton (59) observed that cloud is most
pronounced in the early pickings, and that it decreases and
often disappears during mid-season, and then reappears late
in the season. Elle (35) also found blotchy ripening to be
most severe on fruit from lower clusters. and that it seldom

occurred on fruits from upper clusters later in the season.

11

Steam sterilization. heavy watering. raw organic
manures. heavy defoliation, and excess leaf and vine growth
have been shown to increase the incidence of cloud (59).

Season to season variations occur in the incidence of
blotchy ripening. and it has been suggested by Xidson.and
Stanton (59) that rainy weather during the early part of the
season may affect the incidence of the disorder.

Experiments were conducted to observe the effects of
shade, moisture. soil texture, and cool temperatures on the
incidence of vascular browning by Hall and Dennison (44.
#5). The results indicated that all the above influence
vascular browning. Low night temperature was more effective
when combined with.mist. or shade and mist in the production
of vascular browning. Stanton (105) indicated that light,
,water supply. major. and minor elements also contribute to
the incidence of vascular browning. Ells (35) observed that
heavy watering increased blotchy ripening, and it has been
observed that the weight of rough and unmarketable fruit was
generally higher on shaded plants (2).

Shade and high humidity. separately and in combination,
have been suggested as cloud inducing factors. Kidson (63)
thought that high humidity may not be harmful in the presence
of high light intensity. Frequent watering increased the
effect of high humidity. and partial shading for three weeks
resulted in a lower dry matter content of tomato fruit (Kid-
son 62, 63. 87).

12

Cooper (24. 25). Jones (56). and Jones and Alexander
(5?) concluded that blotchy ripening was increased by shade,
high day temperatures preceded by low day temperatures, high
moisture. and high nitrogen levels.

In another investigation Cooper (23) showed that wide
spacing (6' x 6') of tomato plants and the retention of
auxillary shoots resulted in an increase in the percentage
of uniformly colored fruit. The number of fruit and yield
per plant was increased. but resulted in a decreased mean
fruit weight.

These results do not agree with work done by Ells
(35) and by Kidson and Stanton (59) who found that high
yielding plants tended to produce more blotchy tomatoes:
Ells observed that as the ratio between fruit weight and
green plant weight increased. blotchy ripening increased.

Low temperature (65°F. Day) was reported by Cooper
(22. 26) to reduce the proportion of "greenback“. but
increase the proportion of ”yellow-blotch". The low tem-
perature was also associated with a 20 percent increase in
yield due to an increase in mean fruit size and not to an
increase in fruit number.

Woods (125) and Winsor and Massey (118) indicated
that greenback and blotchy ripening should be classified
separately. These workers found that shade reduced the inci-

dence of greenback, but increased the percentage of blotchy
fruit.

13

Dennison (33) observed that at temperatures above
86°F. tomato fruit developed a yellow color because the red
pigment lycopene was not produced. Hinges, et al. (80).
found blotchy ripening and graywall associated with periods
of low temperatures in the field and the greenhouse (60°-
70°F.) as compared to warm temperatures (70°-80°F.). It
was observed by Gardner (3?) that abundant light resulted in
relatively high sugar levels. especially combined with a
cool night-warm day regime (63°-65°F; night. 67°-75°F. day).
A.high level of soil moisture depressed dry matter, especially
when fruits and plants were shaded. In general, he found the
smallest fruits to be of highest quality.

Controlled environment experiments showed that low
light intensities one or two weeks prior to ripening caused
blotchy ripening. and that the condition.was associated with
reduced sugar content (18. 92. 87).

Gilbert (#1) observed in Hawaii that vascular browning
ceased to appear as soon as the trade winds started to blow
day and night. This happened despite the occurrence of
cloudy. wet, cold spells during the windy period. It was
suggested that the disorder might result from sub-oxidation
injury in affected tissue during periods of little air

movement.

Tobacco Mosaic Infection

Holmes (52. 53) working in the same area of New Jersey

l#
as Haenseler (#3) found a close association between tobacco-
mosaic virus infected plantains (glggtggg_species) growing
near tomato fields or cold frames and the incidence of
blotchy ripening. Both plantains and tomatoes were found to
contain a series of similar but unusual strains of tobacco
mosaic virus (TMV).

Raychaudhuri (93) found. and Boyle (10) confirmed,
that the TMV strain that was associated with internal brown-
ing was not the same as the ordinary strain of TMV.

Boyle (8) and Boyle and Wharton (9) consistently iso-
lated strains of tobacco mosaic virus from internally browned
fruit and from foliage of plants that had produced internally
browned fruit. They observed a negative correlation between
the early appearance of mosaic symptoms and the ultimate
production of internally browned fruit. They showed that
internal browning could be reproduced in large healthy
tomato plants by mechanical inoculation with.an isolate Just
as the first fruit were beginning to ripen, but that inocula-
tion of young plants did not result in internal browning.
These authors concluded that internal browning was a "shock
reaction" resulting from virus invasion of the fruit,
followed by a hypersensitive response of the host, and they
found no correlation between incidence of the disorder and
the rate of fertilizer application. disease spray program

or variety.

Although Boyle and Wharton (9) found no relationship

15
between internal browning and rate of fertilizer application,
Selman (99) found that blotchy ripening appears to respond
differently to potash levels in control and mosaic infected
plants. High potash tended to reduce the incidence of
blotchy ripening in mosaic infected plants, but similar quan-
tities of potash applied to control plants increased the per-
centage of blotchy fruit. In the latter case, Selman sug-
gested that the hardening or growth check. associated with
potash application tended to increase the susceptibility of
the control plants to accidental infection. Rich (9#) also
found that the incidence of internal browning could be influ-
enced by fertilizing. High potassium alleviated internal
browning in virus-inoculated plants. and high phosphorous
tends to obscure the beneficial effect of high potassium.
Rich's results indicated that virus alone would not result
in severe internal browning.

Cotter (28, 29) suggested that when all lack of normal
red color disorders are grouped together. there seemed to be
a difference in fertility effect on fruit color as compared
to browning of vascular bundles, thus suggesting that fruit
color and bundle necrosis could be different in nature. He
distinguished them by referring to than as blotchy ripening
and internal browning respectively. The incidence of internal
browning was not affected by N. K, B. and various infective
conditions of TMV. This report contradicts that of Rich
(9#) as well as the report of Taylor (109) who found that the

16

incidence of internal browning in virus infected plants to
be greatly influenced by nitrogen and boron nutrition. Tay-
lor (109) believed that internal browning was the result of
interference with the movement of reducing sugars to the
developing fruits. Cotter (28, 29) did find that high nitro-
gen levels significantly increased the incidence and severity
of blotchy ripening. and a high potassium level improved
fruit color.

A distinction between graywall, internal browning.
and blotchy ripening was made by Murakishi (8#). Internal
browning appeared to be induced by late infection with
strains of tobacco mosaic virus. and could be seen in either
mature green or ripe fruit. Graywall, on the other hand
appeared to be induced by low light intensities on Thvhfree
plants, but was restricted to green or mature green fruits.
Blotchy ripening was the same as graywall except that the
former appeared on unevenly colored ripe fruit (113). Mura-
kishi (83, 85, 86) noted that during the investigations he
could not distinguish graywall from internal browning by out-
ward symptoms with any degree of certainty. Therefore, dif-
ferentiation was based not on symptoms but on whether the
affected fruit was produced on TMVeinfected plants or TMVA
free plants. Low light intensities were reported to aggre-
vate both disorders.

Jones and Alexander (55, 56, 57) found that under a

low temperature regime followed by high temperature, the

17

number of diseased fruits increased as the potassium level
decreased. The correlation was not as good under normal
temperatures. The percentage of blotched fruit was also
increased by subjecting greenhouse plants to high soil mois-
ture. high nitrogen levels. shade. and injection of plants
with TMV. TCbacco mosaic virus increased the incidence and
severity of blotchy ripening in both field and greenhouse
crops. but blotchy ripening occurred with high incidence

and severity in the greenhouse on plants that tested free

from tobacco mosaic virus.

Cogpgsitiog

Internal as well as external factors have frequently
been associated with blotchy ripening. The composition of
the tomato fruit and plant has been studied and fairly
definite differences between blotchy and non-blotchy fruit
have been found. White (ll#) found that juice expressed
from blotchy areas had diminished capacity for starch
hydrolysis. It has also been indicated that blotchy ripen-
ing susceptibility is related to low starch content in imma-
ture fruit (66).

Brewer (11) found that mosaic infected plants were
characterized by a reduction in total weight and a reduction
in total carbohydrate content. The reduction occurred mainly
in the polysaccharides. Generally. there was no reduction in

the nitrogen content and the carbon-nitrogen ratio was

18
usually lower in diseased plants.

Davies (31) found that the citric acid concentration
was much lower in both the red and green wall areas of
blotchy fruit than usually occurs in normal fruit. This was
accompanied by fairly high concentrations of malic acid,
which was found to be as high in blotchy areas as in unripe
fruit. The red areas of blotchy fruit also had a higher
malic acid concentration than normal fruit.

Hall and Dennison (##) found the Ca. K. Mg. and P.
content to be higher in blotchy fruit than in normal fruit.

Robson (#8. #9, 50. 51) observed that the pectic sub-
stances of both the red and non-red areas were much higher
in blotchy fruit than in uniformly ripened fruit, while pec-
tin methylesterase activity was lower than normal. Blotchy
tomatoes also showed highly significant differences in poly-
galacturonase activity between the green.and red areas. The
activity in the green area was only 16 percent of that in
the corresponding red areas. whether these enzymatic changes
caused blotchy ripening or whether blotchy ripening caused
the enzymatic changes was not determined.

It has been suggested by Kidson and Stanton (60. 61)
that cloud is associated with low dryematter content of fruit
and leaves, and that this condition might be due to excessive
water uptake or to reduced photosynthesis. In most cases the
total solids content of small tomato fruit was higher than
that of larger fruits from the same plant. Analyses of

19
normal and blotchy tomato fruits showed the content of dry
matter, soluble solids, reducing sugars, acidity and nitro-
genous compounds to be lower in blotchy fruit than in normal
fruit (77, 78, 116. 117. 118).

It was observed by Kidson (6#) that high polyphenol
oxidase activity normally decreases as fruit ripen, and that
cloud affected fruit show an abnormal retention of poly-
phenol oxidase activity in the blotchy areas. Walker (110)
found that cloud tissue had a lower phenolic acid content
than healthy tissue the same age.

Observations made by Kidson (67) indicated that the
use of sodium or potassium sulphate to increase the osmotic
concentration of a nutrient solution decreased the incidence
of cloud and also resulted in highly significant changes in
the level of Ca in the plant (67).

Environmental and cultural factors play a role in
fruit and plant composition as shown by Krobonits (69). In
his experiment the dry matter content of tomato fruits was
higher from plants grown on drier. heavier loams than those
grown on wetter soils. A high plant density also increased
dry matter content of fruit.

It has been found that low light intensities decrease
reducing ability of tomato leaves as measured iodometrically
(70). It has also been found that starch. amino acids. and
protein content of leaves of shaded plants were lower than
plants grown under normal light (96, 118).

20

Siegel (100) found that the presence of chloride in
the nutrient solution generally reduced the dry matter con-
tent of the tomato plants. Chloride ions reduced the con-
tent cf glucose. fructose. and sucrose. At high potassium
levels the sugar concentrations were not reduced as much as
they were in solutions with low potassium.

Winsor and Davies (119). Uinsor (122). and Uinsor
et al. (123) found that reducing sugars and total solids in
the expressed sap of fruit were significantly increased by
virus infection. numerous explanations for this may be
available. but the fact that total yield and the proportion
of high grade fruit were reduced may account for the small
but significant increase in sugars and solids. It was also
observed by these workers that total solids. sugars. refrac-
tive index and dry matter content of the fruit was markedly
reduced by partial defoliation. while limiting the number of
fruit per truss resulted in an increase in these values.

It is thus apparent. from the numerous workers cited
that the term blotchy ripening and terms derived from it have
been used with several meanings. many suggestions have been
offered as to its cause. which have resulted in confusion.
and. therefore. blotchy ripening has come to mean little more
than non-uniformly colored fruit. whether or not these dis-
orders are different manifestations of the same trouble or
actually different disorders with different causal agents has

not yet been clearly demonstrated.

FIELD EXPERIMENTATION

Effect 2; Soil Moisture Level and Shade gg,Blotghz
W (1262)

It has been suggested by various workers (59. an. #5.
105. 35 and 41) that frequent watering. defoliation. carbo-
hydrate stress in the fruit at some critical period during
fruit development. and cloudy. rainy weather may increase
the incidence of blotchy ripening.

Most investigators that have indicated adverse environ-
mental factors as possibly being associated with the incidence
of blotchy ripening indicated that the critical period for
induction of the disorder is Just prior to fruit ripening (18.
92. 87). Because the factors resulting in adverse weather
vary from year to year the time of outbreaks of blotchy
ripening would differ from season to season.

An initial study was undertaken to correlate the occur-
rence of blotchy ripening with periods of adverse weather. but
it was found that data available on dates of flower anthesis.
flower set. harvest dates. and severity of blotchy ripening
in Michigan were not complete enough to be correlated with
available weather data. Because of this. the most susceptible
size or stage of development at which tomato fruit develop
blotchy ripening could not be determined by correlation com-

pari 80118 e

21

22

For these reasons an attempt was made to partially
simulate environmental conditions in the field that had been
indicated in the literature as being associated with the
incidence of blotchy ripening and evaluate their inffluence
on the disorder.

Because many different factors have been indicated as
being associated with the occurrence of blotchy ripening. it
was decided to use treatments including more than one factor.
and if a particular treatment resulted in significantly more
blotchy fruit. the separate factors could be identified in

further work.

Procedure:

Seed of the tomato varieties Bird's Nest and Fireball
were sown on April 4, seedlings were maintained in a green-
house. and transplanted into the field on May 26. Eight-
hundred pounds of 5-20-20 fertilizer and 40 tons of manure
per acre were applied and worked into the soil before trans-
planting. On July 2. a side dressing of 100 pounds per acre
of ammonium nitrate was applied.

A randomized complete block design was used. It
included a comparison of the varieties and of shaded and
unshaded plots. with two replications. There were nine
plants per plot on two foot centers in the row and three
feet between the rows.

The material used to shade the plots was Lumite saran

23
shade fabric (Chicopee Manufacturing Corporation. Cornelia.
Georgia). It covered the whole plot and reduced light
intensity by 72 percent as measured in foot candles by a
model 756 Heston Illumination meter. The shade fabric was
suspended approximately six-inches above the tomato plants.
The shaded plots received a inches of water over a # day
period starting at the time they were covered. and in addi-
tion.were also sprayed three times daily with approximately
3 quarts of water. The addition of the 4 inches of water
and the spray insured a high level of available soil mois-
ture and humidity. Shades were placed over the variety
Bird's Nest and Fireball on July 9. and July 19 respectively.
and remained over the plots 14 days.

At harvest the fruit were classified blotchy when 10
percent of their surface area was affected. The number and
weight of blotchy and nonblotchy fruit was recorded for each
harvest. and percent soluble solids were determined with a
hand refractometer.

.A preliminary investigation of sampling technique for
percent soluble solids was conducted. Soluble solids from
the following portions of Fireball and Bird's Nest fruit
were sampled to determine if significance differences existed
among them: 1. the upper one-quarter of the fruit or calyx-
end. 2. the walls of the middle half of the fruit. 3. the
internal placental tissue. and h. the bottom one-quarter or
blossom-end of the fruit.

24
Soluble solids were determined from blotchy and from
normal fruit from both shaded and control plots. The aver-
ages used for the analyses of variance represented 20 fruit.
The analyses of variance were performed on the result-
ing data as indicated by Snedecor (103) and mean comparisons
made by the method described by Duncan (3#).

Results and Discussion:

Neither yield nor the incidence of blotchy ripening
were influenced by the shade plus the initial four-inch
application of water. and there was no difference in the
incidence of blotchy ripening between the variety Fireball
and Bird's Nest (Table 1).

From the preliminary investigation of percent soluble
solids. it was found that there were differences in soluble
solids among the various portions of the fruit that were
sampled (Table 2A). wall tissue from the middle one-half of
the tomato fruit were used for all subsequent soluble solids
determinations.

Only a # percent difference in percent soluble solids
was found between blotchy and normal fruit (Table 2C).
Although there was no significant difference in percent
soluble solids between fruit from shaded and control plots.
fruits from control plots averaged 13 percent higher in
soluble solids than fruit from shaded plots (Table 2B).

Elle (35) suggested that blotchy ripening might be
caused by insufficient photosynthate for fruit development

25

TABLE 1.--The Influence of Shade and Hugh Soil Moisture on
Blotchy Ripening.

 

 

Shade Plus
Treatment: .gontrol High Soil Moisture

Blotchyl/ an-Blotchy Blotchy Non-Blotchy

Bird's Nest: % x Z Z
Frt. Wt./Plant 6.2 42 8.5 58 5.6 50 5.5 50
Frt. NO./P1ant 40 52 37 48 55 58 4O 42
Avg. Fruit

Weight (lbs) .15 .22 .10 .13
Fireball :

Frt. Wt./Plant 9.0 56 7.0 44 13.8 67 6.8 33
Frt. NO./Plant 39 53 34 46 5O 66 26 34
Avg. Fruit

Weight (lbs) .23 .20 .28 .26

 

 

;/ Blotchy fruit were those with yellow discolored areas on
more than 10 percent of their surface area.

26

TABLE 2.--Variation in Percent Soluble Solids of Tomato Fruit.

 

 

A: Average soluble solids of indicated portions of tomato
fruits.

 

 

 

Area of Soluble Statistical
Fruit Sampled Solids(%)q Significance*
Calyx-end tissue 3.96 a
Mid-outside wall tissue 4.25 b
Placential tissue 4.63 c
Blossom-end tissue 4.80 d

B. Average soluble solids of tomatoes grown on shaded and

control plots. ____g
Shaded plots n.13l/ a
Control plots 4.69 a

 

C: Average soluble solids of blotchy and normal_tomato fruits.

Blotchy fruit 4.32l/ a
Normal fruit 4.49 a

l/ Averages include both Fireball and Bird's Nest fruit:
samples from the calyx-end. the mid-outside wall tissue.
placental tissue and the blossom-end tissue of tomato
fruits.

* Means with uncommon letters are significantly different
at 5% level.

‘.

27
when small plants were heavily laden with a crop of tomato
fruit. Others (59. 44. 45) have indicated that heavy water-
ing. and cloudy weather are associated with the incidence of
blotchy ripening.

While the plants were not particularly small. and did
not carry an unusually large load of fruit. the shade mater-
ial might have reduced carbohydrate levels by reducing photo-
synthetic activity. If a shortage of carbohydrates is a fac-
tor in the develOpment of blotchy ripening. the low light
intensities associated with cloudy. rainy. weather would help
explain results of other workers that have associated blotchy
ripening with periods of inclement weather.

Another possibility is that under high humidity. low
evaporation. low light intensities. cloudy atmospheric condi-
tions and rainy weather the water balance of the tomato plant
and fruit might become upset and lead to the development of
blotchy ripening.

Results indicate that the treatment employed was not
effective in inducing more blotchy ripening than occurred on
the control plots. However. 42 and 56 percent of the fruit
on a weight basis. and 52 and 53 percent on a fruit number
basis. from the respective control plots of Bird's Nest and
Fireball were classed as blotchy (Table 1).

Because a large percentage of fruit from the control
plots were affected with blotchy ripening there were environ-

mental conditions during 1962 that contributed to the

28
deve10pment of blotchy ripening. The season was not favor-
able for measuring the effectiveness of the treatment in

inducing blotchy ripening.

Effect 2; Various Treatments 2; the Incidence of

Blotchy Ripenigg

Procedure :

The following treatments were a continuation of the
previous study: 1. 90 percent shade with an initial applica-
tion of 4 inches of water over a period of 4 days. 2. pruning
1/3 to 1/2 of the mature leaves from the plants. 3. removal
of 1/2 of the fruit over 2 inches in diameter. 4. misting the
plants by an automatic misting apparatus and 5. a control.

.A split plot arrangement with.main plots in.3 random-
ized complete blocks was used. The main plots consisted of
three varieties: Fireball. Moreton Hybrid. and Burpee
Hybrid. Each treatment consisted of 6 plants set with 25 by
5 foot spacing. Only data from the 4 middle plants in each
treatment were recorded.

The shade cloth.was placed over the plots 7-10 days
before the first harvest. and remained over the plots for 14
days.

An.automatic misting apparatus was set up and moved
when the shades were moved. The length of the misting period
was regulated by a Mist-Ashatic-hodel B control system (8. C.
Geiger. Nerth‘flales. Pennsylvania). The interval between

29
mistings varied with.water accumulation and evaporation rate
from a counterbalanced metal screen. which controlled a
solenoid valve. The counterbalance of the screen was
adjusted so that the misting cycle was synchronized with
evaporation from the plant foliage. Misting did not add any
appreciable amount of water to the soil.

One-third to one-half of the mature leaves were
removed on July 16. July 27. and August 23. for the varieties
Fireball. Moreton Hybrid. and Burpee Hybrid. respectively.

One-half of the fruit over 2 inches in diameter were
removed from Fireball. horeton Hybrid. and Burpee Hybrid
plants on replicated plots on July 20. July 31. and August
25. 1962.

At harvest. fruit were graded into three classes:
non-blotchy (less than 10 percent of the fruit's surface
area affected). slightly blotchy (lo-25 percent). and

severely blotchy (over 25 percent of surface showing defect).

Results and Discussion:

NOne of the treatments affected the incidence of
blotchy ripening or yield. However. yield and the percentage
of blotchy fruit were influenced by variety. The variety
Fireball and Horeton Hybrid produced a significantly larger
percentage of fruit classes as severely blotchy than Burpee
Hybrid (Table 3).

The yields recorded in Table 3 include only ripened

30

TABLE 3.--The Influence of various Treatments on Fruit Size.
Yield. and the Percentage of Blotchy Ripening.

 

 

 

 

 

 

 

 

 

 

 

mam Average W
Ripe Fruit Weight Slightly Severely
Treatment For Plant Per Frt Nermal Blotchy Blotchy
Nb. lbs lbs Ht. No Ht. No Ht No
variety: FIHEBALL
90$ shade 64 10.9 .17 37 38 37 34 25 28
Defoliation 68 16.6 .24 47 47 29 31 24 22
Auto-mist-
ing 65 15.3 .23 39 41 33 35 27 23
Defruiting 56 13.3 .23 48 51 29 27 23 21
Control 69 15.2 .22 44 45 47 35 21 20
varietz:_. BUBPEE HIBR
90$ shade 17 7.1 .41 65 70 34 29 0.1 0.2
Defoliation 21 8.6 .41 60 63 39 36 1.1 0.2
AutOdmist-
ing 18 6.9 .28 73 72 25 26 2.7 2.2
Defruiting 13 5.5 . 2 57 60 42 39 0.3 0.6
Control 13 5.8 .44 65 69 35 31 0.0 0.0
Variety: 0 TON R .1
901 shade 36 24.6 .68 39 60 4g 28 17 ll
Defoliation 47 21.8 .46 51 53 3 33 15 14
Autoemist-
ing 37 15.0 .40 59 51 32 40 8. 8
Defruiting 33 14.5 .43 44 45 45 45 ll 10
Control 39 17.6 .45 44 46 50 45 6 8

 

 

 

 

 

 

_1/ Normal. less than 10$ of fruit's surface area affected with
blotchy tissue

Slightly Blotchy. 10-25% of fruit's surface area affected
with blotchy tissue

Severely Blotchy. more than 251 of fruit's surface:
affected with blotchy tissue

area

31
fruit. .A large percentage of the fruit of Burpee Hybrid
were green at the time of the first killing frost in the
fall and was not included.

The treatments had no affect on average fruit weight
of fruit classed as normal. slightly blotchy or severely
blotchy (Table 4). Generally. fruit from the two blotchy
classes were slightly larger than normal fruit.

There were no significant differences in percent
soluble solids of fruit among treatments or between normal
and blotchy fruit. However. fruit classed as normal did
average slightly higher in percent soluble solids than fruit
from the two blotchy classes (Table 5).

Again as in the case of the previous study. a large
percentage of the fruit produced by plants growing on the
control plots was affected with blotchy ripening. making it
difficult to determine if the treatments were effective in
inducing blotchy ripening.

Enzirgnmental Influences 9g,Blotcgy Ripenigg (1263)

Again as in 1962 experhments were conducted to simu-
late environmental conditions that might be associated with

blotchy ripening. Emphasis was placed on evaluating factors
affecting the water balance of the plant.

Procedure:

Seed of Fireball and Glamour were sewn on April 15.

32

TABLE 4.--The Effect of variety and Treatment on Average
Fruit Size.

 

 

 

 

 

 

 

 

 

Slightly Severely Mean
variety and Nermal Blotchy Blotchy Fruit
Treatment Fruit Fruit Fruit Weight

(lbs;) 1125;) (lbs;) (lbs.)
FIRE
9O shade .16 .19 .15 .17
Defoliation .24 .23 .26 .24
Auto-misting .22 .22 .27 .23
Defruiting .22 .25 .25 .23
Control .21 .22 .22 .22
BURPEE BID
90 shade .39 .47 .35 .41
Defoliation .39 .43 .40 .41
Defruiting .39 .43 -- .42
Control .42 .51 -- .44
MORETON HIE
903 shade .44 1.03 1.04 .68
Defoliation .45 .46 .50 .46
Auto-misting .46 .32 .29 .40
Defruiting .43 .44 . 5 .43

 

 

Normal. less than 10% of fruit's surface area affected with
blotchy tissue

Slightly Blotchy. 10-25% of fruit's surface area affected
with blotchy tissue

Severely Blotchy. more than 25% of fruit's surface area
affected with blotchy tissue

33

TABLE 5.--The Effect of Treatments on the Percent Soluble
Solids of Normal and Blotchy Fruit of Fireball Tomatoes.

 

 

90%- Defolia- Auto- Defruit-

 

Shade tion _misting_ing Control Average
Fruit
Classes Soluble Solids
Normal 4.8 4.1 4.0 4.2 4.3 4.2
Slightly-
Blotchy 4.1 4.2 4.0 4.0 4.2 4.1
Severely-
BlOtOhy “.0 “.3 4.0 ue3 uel he].

 

Each value represents the average of approximately 20 deter-
minations.

A composite sample of both blotchy and normal tomato fruit
tissue from the walls of the middle half of the fruits were
used for these determinations.

34
1963. transplanted into 3 inch veneer bands on May 1. and
planted in the field on May 30. 1963. Five-hundred pounds
of 10-20-20 fertilizer per acre was applied to the field
before the tomatoes were transplanted. and l/2-pint of 10-
52-17 starter solution (3 lbs./50 gal. water) was applied to
each plant at transplanting.

The field plot design.was a split-split plot with two
replications. The first split was between moisture levels.
the second between varieties. and the third among treatments.
Each plot consisted of four plants spaced at 3 x 6 feet.
Records were taken from the two center plants in each plot.

An attempt was made to maintain two moisture levels
in the field during the growing season of 1963: l. a mini-
mum of 80 percent available soil moisture. and 2. a minimum
of 40 percent available soil moisture. Delmhorst soil
blocks were placed in the soil at depths of 6 and 15 inches
in 12 locations. An average of readings from the two differ-
ent depths was used to determine the time of irrigations.

The following treatments were employed: 1. applica-
tion of calcium chloride at a rate of 1500 lbs. per acre. 2.
foliage applications of phenylmercuric acetate. 3. misting
plots with water. 4. shading. 5. a combination of plastic
windbreaks and misting. and 6. plastic windbreaks alone.

A solution of calcium chloride was applied on July 29
to increase the osmotic concentration of the soil solution.

Phenylmercuric acetate (PMA). a chemical reported to

35
influence transpiration (126. 127) was initially applied on
July 29 to the tomato plant foliage as a spray at a concen-
tration of 3.3 x 10'“M. Repeated applications were made at
10 day intervals throughout the season. A preliminary experi-
ment was conducted with FHA before field application. The
procedure described in the following study on influence of
chemicals on transpiration was used. except the variety used
was Fireball.

Two types of shade material were used. a coarse nylon
material that reduced light intensity. as measured by a foot
candle meter. by 20 percent. and a finer textured material
that reduced light intensity by 70 percent. The 20 percent
shade material was placed approximately 6-inches above the
tomato varieties Fireball and Glamour on July 22. well in
advance of fruit ripening. The 70 percent shade material
was placed over the light shade material. resulting in an
approximate 90 percent reduction in light intensity. at the
time the fruits in the first cluster were in the white-star
stage of ripening. The 70 percent shade material was placed
over the tomato variety Fireball on July 30 and over the
tomato variety Glamour on August 9. 1963. and remained over
the plants for 20 days.

Histing of plants was performed by the same equipment
described previously. and the influence of misting upon rela-
tive humidity was determined with a battery powered psy-

chrometer.

36

Windbreaks of 44mil clear plastic 2% feet high were
placed on both sides of the plant rows on July 23. 1963.

In a supplemental study. clear and green plastic windbreaks
were placed in an cpen area to determine their effect on
temperature and humidity. Thermocouples. connected to a
Minneapolis Honeywell temperature recorder. were placed
between the windbreaks at three different heights above the
ground surface (4. 12. and 24 inches) and in an.adJacent
open area at the same heights to serve as a control.

Humidity determinations were measured between the
windbreaks at ground level and at 12 inches above the ground
surface with a battery powered psychrometer.

Soluble solids determinations of Fireball and Glamour
fruits were taken throughout the season with a hand refrac-
tometer.

Fruits were graded into the following three classes:
1. uniformly colored including those with less than 10 per-
cent of their surface blotchy. 2. those with 10—25 percent
of their surface area blotchy. and 3. fruits with more than
25 percent of their surface area blotchy.

The growth rates of fruits from the different treat-
ments were compared to determine if rate of fruit growth and
swelling was associated with the incidence of blotchy ripen-
ing. and to determine if the different treatments induced
changes in rate of fruit growth.

The diameters of two fruits on each of two plants

IL

37

from each plot were measured with direct reading calipers
from July 26 to September 6. To insure that fruit diameter
measurements taken on different dates would be taken at the
same points on the fruit. a small dot was applied on each
side with a marking pencil. and the caliper's tips were
placed on these dots at each measurement.

Because fruits selected for measurement were of
slightly different diameters and because some fell off of
the vine or ripened early and had to be substituted by other
fruits. increase in growth.was expressed as percentage
increase in fruit diameter.

The analyses of variance were performed on the result-
ing data as indicated by Snedecor (103) and mean comparisons
made by the method described by Duncan (34).

Results and Discussion:

Results from a preliminary experiment utilizing PMA
showed that the chemical reduced water loss by 15 percent.
The relative humidity in the peripheral foliage of misted
plants was 10 to 40 percent higher than that recorded in cor-
responding nonqmisted plants. The supplementary windbreak
studies showed that temperatures recorded within the green
plastic windbreaks were lower than those recorded within the
clear plastic windbreaks. or in the adjacent open area (Table
6). Temperatures recorded between the clear plastic wind-

breaks and adjacent open area were approximately the same

38
(Table 6). Relative humidity between the clear plastic wind-
break was found to be 3.7 percent higher at ground level than
in the open control area. However. at a height of one feet
above the ground the relative humidity between the clear
plastic windbreaks was 38.2 percent higher than that recorded
in the open.area at the same height (Table 7).

There was no differences in weight of Glamour fruit
per plant or in number of fruit per plant among the different
treatments (Table 8).

There was no differences in number of fruits produced
by plants of the variety Fireball grown on the calcium
chloride treated plots. the shaded plots. or the plots
sprayed with phenylmercuric acetate. Plants subjected to
the calcium chloride treatment produced more fruit. on a num-
ber basis. than was produced by plants grown on the control
plots. the misted plots. the plots protected by windbreaks
or the plots that were protected by windbreaks and misted
(Table 8).

with respect to the weight of fruit produced by plants
of the variety Fireball. those plants grown on calcium
chloride treated plots produced more fruit than were produced
by plants subjected to the combination treatment of misting
and windbreak protection. There were no differences in the
weight of fruit produced per plant among the remaining treat-
ments (Table 8).

with respect to severeness of blotchy ripening it was

39
TABLE 6.--The Influence of Windbreaks Upon Temperature.

* J fiL——
——- Ir‘

 

 

Height of Temp. Clear Green

Measurement Plastic Plastic No-

Abov Ground Nindb eak H db ak N break
a” 92.63‘. 89e9b 920]-a
12' 91.6a 87.1b 90.5a
21'I 91.8a 87.4b 9l.la

 

 

* a. b. are for values in the same horizontal column.

Means with uncommon letters are significantly different at
5% level.

TABLE 7.-~The Influence of Nindbreaks Upon Relative Humidity.

 

 

 

 

Between Adjacent

Clear Open Percentage
Height __p Uindbreak Area Difference
Ground-level 75.0 72.2 3.7

l-Foot Above
Ground 70.8 43.7 38.2

 

 

 

 

 

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41
found that the relatively larger fruit tended to be most
severely affected with blotchy ripening. In the case of fruit
from the variety Fireball there was no differences in.average
fruit weight for the different classes of fruit. The average
weight of Glamour fruits with more than 25 percent blotchy
tissue were found to be significantly heavier than fruits
classed as normal (Table 9).

A significant difference in percent soluble solids of
4.7 percent between Fireball fruits classed as normal and
fruits affected with blotchy tissue on more than 25 percent
of their surface area was found (Table 10). There were no
differences in percent soluble solids among classes of
Glamour fruit (Table 10).

Relatively larger tomato fruits have been shown by
MacGillivray and Clements (75) and by Gardner (37) to be
lower in total solids and sugars than smaller fruits. These
findings may partially explain why the larger fruit in this
study tended to be affected with blotchy ripening.

Nermal tomato fruit tissue was found to be signifi-
cantly higher in soluble solids (9 percent higher in Fire-
ball fruits. and 7 percent higher in Glamour fruits) than
blotchy tissue from the same tomato fruits (Table 11).

There was a significant interaction between treat-
ments and moisture levels with respect to percent soluble
solids for the variety Fireball. but not for the variety
Glamour (Table 12). Percent soluble solids of Fireball

42
TABLE 9.--Relationship of Fruit Size to Blotchy Ripening.

W

 

 

 

 

 

Hm GLAMOU
Average Average
Height Weight
Class (3.1~ Class. (5.1
25% Blotchy 93.42 a 25% Blotchy 184.35 a
10-25% Blotchy 93.10 a 10-25% Blotchy 169.75 b
NOrmal 91.28 a Nermal 162.17 b

 

 

 

 

* Means with uncommon letters are significantly different
at 5% level.

TABLE lO.--Mean Percent Soluble Solids of Fireball and
Glamour Tomatoes Classed as Normal and Blotchy.

 

 

 

 

 

 

 

lEIBEQALL__ Qééflgflfi
% Soluble % Soluble
Clggg §olid§ _gy§§§_ Solids
Normal 3.74 a Nermal 4.38 a
10-25% Blotchy 3.63 ab 10-25% Blotchy 4.34 a
25% Blotchy 3.57 b 25% Blotchy 4.31 a

W

* Means with uncommon letters are significantly different
at 5% level.

43

TABLE ll.--Average Percent Soluble Solids of NOrmal and
Blotchy Tissue from Tomato Fruit of the varieties
Fireball and Glamour.

 

FIREBALL GLAMQQR
NOrmal Blotchy Nermal; Blotchy
3.7 a 3.4 b 4.4 a 4.1 b

 

 

* Means with uncommon letters are significantly different
at 5% level.

44

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45
fruit from the low moisture plots averaged 12 percent higher
than fruit from the high moisture plots. Glamour fruit from
the low moisture plots were also slightly higher in percent
soluble solids than fruit from the high moisture plots
(Table 12).

Other workers (60. 61. 69. 96. 117) have also indicated
that high moisture levels or environmental factors that reduce
transpiration losses often resulted in fruits with low percent
soluble solids. reduced amounts of sugars. and lower dry
matter.

Generally. fruits from treatments designed to reduce
moisture stress or carbohydrate levels were lower in soluble
solids than the control. Shaded plants and plants that were
both protected by windbreaks and misted produced fruit with
the lowest soluble solids in both Fireball and Glamour (Table
12). The calcium chloride treatment. which was used to
increase the moisture stress. had no affect on soluble solids
(Tab1e_12).

Growth rates of fruits from both Fireball and Glamour
tomato varieties were influenced by the various treatments
employed in this study. However. no significant differences
in fruit growth rates between high and low moisture levels
were recorded for fruits of either Fireball (Table 13) or
Glamour varieties (Table 14).

Fireball plants treated with FHA. which was shown to

reduce transpiration. produced fruits that increased in

46

TABLE 13.--The Influence of various Practices. Treatments.
and Soil Moisture Levels Upon the Average Rate of Increase

of Fireball Tomato Fruit Diameter.

 

 

 

low thh Treatment
Treatment Moisture Moisture Means

Moisgure x treagment means
Phenylmercuric acetate 3.70 2.75 3.22 a
Windbreak 2.50 3.00 2.75 b
Control 2.65 2.50 2.57 bc
Misting 2.40 2.45 2.42 cd
Shade 1.60 2.85 2.22 do
Windbreak + Misting 2.20 1.85 2.02 e
Calcium Chloride 1.60 2.40 2.00 e
Moisture Level Means: 2. 2. l

——

 

 

 

* Means with uncommon letters are significantly different at

5% level.

L.S.D. to compare means of treatments at the same moisture

level-LeSeDe = e92

.05

L.S.D. to compare means of the two moisture levels within

the same treatment-L.S.D.

= .52

.05

values are the average percent increase in fruit diameter.
measured at 4 day intervals. from July 26 to September 6.

1963.

l+7

TABLE l4.--The Influence of various Treatments and Soil Mois-
ture Levels Upon the Average Rate of Increase of Glamour
Tomato Fruit Diameter.

 

Ii

 

 

Treatment Treatment Meansl/
Nindbreak + Misting 4.97 a
Misting 4.47 b
Windbreak 4.45 b
Control 4.42 b
Calcium Chloride 4.30 b
Phenylmercuric Acetate 4.30 b
Shade 3.75 c

 

 

1/ values are the average percent increase in fruit diameter.
mezsured at 4 day intervals from July 26 to September 6.
19 3.

* Means with uncommon letters are significantly different
at 5% level.

48
diameter at a more rapid rate than fruit from plants sub-
jected to the other treatments (Table 13). The phenylmer-
curic acetate treatment appeared to be more effective in
inducing a more rapid rate of fruit growth with a low soil
moisture level than with a higher soil moisture level (Table
13).

On the other hand. plants subjected to the calcium
chloride treatment. which was applied to induce a higher
moisture stress. produced fruit with the slowest growth rate.
This supports the views expressed by Bartholmew (4). Hen-
drickson and veihmeyer (47). Magness et al. (76). Anderson
and Kerr (1). and MacDougal (74) that when an internal water
stress develops because of low soil moisture and high trans-
piration. water usually moves from fruits to leaves with a.
resultant decrease in rate of fruit growth.

It appears that the significantly greater rate of
fruit diameter increase induced by PMA may indicate that an
excess amount of water might be incorporated into fruits
under climatic conditions conducive to low transpiration in
combination with high levels of available soil moisture. .A
trend for larger fruit to be more severely affected with
blotchy ripening has already been mentioned. Thus. the
amount of water retained in the fruit tissue could be an
important factor in determining if tomato fruit develop
blotchy ripening.

Cooper (22) presents data supporting the idea that

49
conditions conducive to low transpiration are associated with
blotchy ripening. He reported low day temperatures increased
the incidence of yellow-blotch and that a 20 percent increase
in yield was also associated with cool day temperatures.
Increased yield was due to increased mean fruit size and not
increased fruit number. This would imply that the increased
yield was a result of more water being incorporated into the
fruits because of less water loss from the plant's leaves.
hinges et al. (80) reported similar findings. Observations
reported by Kidson.and Stanton (59) and Gilbert (41) imply
that low transpiration may also be involved in the production
of blotchy ripening. These results also suggest that fruits
with higher water contents tend to have a higher incidence
of blotchy fruit.

As already mentioned. the growth rate of fruit of the
variety Fireball grown.on calcium chloride treated plots was
slowest of any treatment. The fact that plants grown on cal-
cium chloride treated plots did produce a larger number of
fruit per plant suggests that there may not have been as much
photosynthate per fruit as was available to fruit grown on
plants from the other treatments. If this were true. it would
probably result in smaller fruits. There is. however. data
that suggest that lack of water contributed to the slow rate
of fruit growth.and smaller fruit size. especially under a low
moisture regime (Table 13). Growth rates of tomato fruit from
calcium chloride treated plots in combinations with the higher

5O
soil moisture level were not significantly different from
growth rates of tomato fruit from the high moisture control
plant. but growth rates of fruit from calcium chloride treated
plots in combination with low moisture were significantly
lower than the low moisture control and the growth rate of
fruits from plants subjected to the calcium chloride-high
moisture regime. It thus appears that the calcium chloride
treatment was effective in reducing rate of fruit growth under
the low moisture condition.

It had been anticipated when the experiments were set
up that the calcium chloride would increase the osmotic con-
centration of the soil solution. and thereby reduce the
amount of available water that could be taken up by the plant
and incorporated into the fruit. and this in turn would tend
to reduce the incidence of blotchy ripening. A partial
explanation as to why calcium chloride was not effective in
reducing blotchy ripening may be in the paper presented by
Siegel and Bjarsh (100). They found that the presence of
chloride in nutrient solutions generally reduced the dry
matter content of plants and also reduced the glucose. fruc-
tose. and sucrose content of tomato plant. Geraldson (39)
found that nutrient solutions with a low nitrate/chloride
ratio were associated with more severe blotchy ripening.
Consequently. it would appear from the results of Siegel and
BJarsh and Geraldson that the influence of chloride in reduc-

ing the amount of dry matter. glucose. fructose. and sucrose

51
may have offset any beneficial affects a soil solution of
high osmotic concentration might have had on reducing blotchy
ripening.

Growth rates of tomato fruit of the variety Glamour
do not appear to be as easily influenced by manipulating mois-
ture levels surrounding the plants as are growth rates of
fruit of the variety Fireball (Table 14). This is illustrated
by the fact that the growth rates of Glamour fruits produced
on misted plots. plots protected by windbreaks. calcium
chloride treated plots and phenylmercuric acetate treated
plots are not different from the growth rate of fruit from
control plants. whereas. there were significant differences
in rate of fruit growth induced by these same treatments on
fruit of the variety Fireball (Table 13).

Not only are fruit growth rates of the variety Glamour
not as easily influenced by different moisture levels. the
treatments do not affect the growth rate of fruits in the
same way as they affected growth rates of Fireball fruits.

It can be seen in Table 14 that Glamour plants grown on the
plots that were both misted and protected by windbreaks pro-
duced fruit that increased in diameter at a significantly

more rapid rate than did fruits from the other treatments.
while plants grown on the shaded plots produced fruit that

grew at a slower rate than did fruits from the other treatments.

Glamour tomato plants had a larger root system and
leaves that were more pubescent than did the variety Fireball.

52
This may explain why Glamour plants were not as easily influ-
enced by the different moisture levels as were Fireball
plants.

Winsor and Davies (119) have found a close relation-
ship between the refractive index from expressed sap of
tomato fruits and the total soluble solids of tomato fruits.
which in turn are closely correlated with their sugar content.
Thus. percent soluble solids are an indication of quality of
the tomato fruit. It was suspected that treatments which
tended to reduce transpiration and/or reduce photosynthetic
activity would reduce percent soluble solids of tomato fruit.
Such a response was indirectly implied in the data of vari-
ous workers (60. 61. 69. 96. 118. 14) who found that such
factors as high soil moisture levels. overcast. cool. rainy
weather often resulted in fruit with low soluble solids.
reduced amounts of sugars. and lower dry matter.

In general. plants grown under treatments that tended
to reduce transpiration and/or photosynthetic activity tended
to have fruits that averaged lower in soluble solids than
plants growing on the control plot (Table 12).

Although none of the treatments employed in the field
during 1963 significantly increased or decreased the amount
of blotchy ripening. some general trends were noted. Fruit
with more than 25 percent of their surface area affected
with blotchy tissue tended to be larger (Table 9). and fruit
affected with blotchy ripening tended to have lower percent

53
soluble solids (Table 10). It was also noted that blotchy

tissue was lower in soluble solids than the normal tissue

of the same fruit (Table 11).

The Influence 9;.Loculgr Seed Density g; the Localization
of Blotchy Ripenigg

Field observations in 1963 indicated that there was
an apparent relationship between localization of blotchy
ripening and tomato fruit locules of low seed density. This

idea was pursued in the following investigation.

Procedure:

Tomato fruits with varying amounts of their surface
area affected with blotchy ripening were obtained from both
the local market and the Horticulture farm at East Lansing.
This sampling procedure insured that diverse growing areas
and culture practices were represented as well as different
varieties.

The number of seed underlying normal and abnormal por-
tions of outer wall tissue was determined by either counting
the seeds in an entire locule or by counting seeds obtained
in a core sample taken through the locule. when a core sample
was used. it was taken transversely through the center of the
locule with a cork bore. Seed counts. except where all seeds
in a locule were counted. are expressed as the number of seeds
found under a square centimeter of surface area. Seed counts.

which in all cases were obtained from normal and affected

54
locules within the same fruit. were summarized and compared
by appropriate statistical methods.
The number of seeds underlying normal and blotchy
tissue was also determined for a 65 fruit sample from tomato
varieties Fireball and Glamour which.were grown in the green-

house in the early spring of 1964.

Results and Discussion:

locular areas under normally colored outer wall tissue
based on 12 to 4? fruit per sample. average 13 to 93 percent
higher in seeds per unit area than those observed under
affected outer wall tissue (Table 15). When the seven samples
of fruit obtained at the local market were combined involving
93 fruits. 50 percent more seeds were found under normal than
under blotchy wall tissues of the same fruits. And when all
14 samples were combined. involving 236 fruits. 40 percent
more seeds were observed under the normal tissue than under
blotchy tissue (Table 15).

Figure 2 illustrates the relationship of seed density
to blotchy ripening in a large fruit. The locules below
normally colored tissue contained from 22 to 62 seeds. while
those under blotchy tissue contained from O to 17 seeds.

Only a small percentage of the fruit examined showed such a
clear relationship between low seed density and the incidence
of blotchy tissue. In most fruits where locules were of more
uniform size. actual seed counts were generally required to

distinguish differences in seed number underneath blotchy and

55

TABLE 15.--Relation of Seed Per unit Area in Blotchy and
Non-Blotchy Areas of the Same Fruit. Field 1963

 

 

 

Number Average ber of % Increase
of seedgcm in seed in

Source variet uits Blotc an-Blot Non- late

I

r e 3

Benton Harbor Fireball 12 2.9 5.6 93**
Bay City unknown 15 1.1 1.5 36
Essexville unknown 14 1.8 1.5 67
Circle unknown 13 2.4 3.9 62*
Unknown unknown 12 2.1 3.9 86**
unknown unknown 14 4.5 5.1 13
unknown unknown 13 1.7 2.6 53
Combined
Market
Tatal " 93 3 o u 5 o 1 50*.
EQEEAEBLEEEE
222!
East Lansing Cardinal 18 5.1 7.6 49**
East Lansing Fireball 14 7.9 10.5 33
East Lansing Glamour 23 4.3 6.8 58**
East Lansing Fireball 47 4.8 7.1 48**
East Lansing Glamour 8 34. 23 43. 8a 28
East Lansing Cardinal 9 44.69' 57.0 28
East Lansing Fireball 24 19.4a 28.6a 47**
Combined
Tbtal - 236 8.2 11.5 40*

~ -
—._* —‘-‘—“

* 5 percent level of significance. ** 1 percent level of sig-
nificance.

a. Indicates average seed number for entire locule.

56

 

 

 

Fig. 2 Cross section of tomato fruit indicating relation-
ship between 1ow seed density and incidence of
blotchy tissue. Areas designated (n) normal con-
tained from 22-62 seed per locule. those designated
(b) blotchy. contained less than 22 seeds per
locule.

57

non-blotchy tissues.

These results were verified by a 65 fruit sample
including fruits from varieties Fireball and Glamour that
were grown in the greenhouse in the early spring of 1964.

It was found that there was 40 percent more seed underneath
normal tissue than under blotchy tissue. From a sample of
75 fruit. there was an average of 38 seed per locule under-
lying normal tissue and only 27 underneath blotchy tissue.

Ells (35) mentioned that blotchy areas were more
prevalent between the fruit's septa. but offered no explana-
tion as to why blotchy ripening in outer wall tissue should
occur more commonly between the septa than over them.
Observations made during this study confirm Ells' findings
that blotchy tissue was found predominantly between the
fruit's septa. However. it should be pointed out that some
tomato fruit display blotchy areas that extend into outer
wall tissue that is over septa tissue. Data collected in
this study indicate that localization of blotchy areas in
the wall tissue is associated with underlying locules of low
seed density.

An explanation of the association of localized blotchy
ripening in outer wall tissue areas above locules containing
a low seed number was deduced from the reports of previous
investigators.

Auxin production in the early stages of fruit growth
moves to the ovary tissue surrounding the young embryo (42).

58
In later stages the major source of auxin is the young
developing embryo (124. 73. 81). The very important role
that auxins play in development of fruit has been demon-
strated by Nitsch (88) working with strawberry fruits. His
experiments indicate that auxin produced in the developing
achene was the major factor contributing to fruit growth.
Thus. it has definitely been shown that the seeds of fruits
play a key role in the fruit's development.

On the basis of these findings one might further postu-
late how seed number might influence the development of
blotchy ripening. White (114) demonstrated that Juice from
blotchy tissue had a lower amylase activity than from non-
blotchy tissue and postulated that blotchy ripening is asso-
ciated with decreased starch hydrolysis and sugar content.
Ells (35) furthered this hypothesis by demonstrating that
soluble solids content of Juices from blotchy tissues were
lower than those from non-blotchy tissues. Skoog and Robin-
son (101). Audus (3). and Mitchell et a1. (82) indicated
that auxins are associated with the transition of poly-
saccharides to sugars. Because seeds are an important source
of diffusible auxins in fruits. seed numbers may be linked to
auxin imbalance and to lower sugar content found in blotchy
as compared to non-blotchy areas of fruit. Seed number.
through auxin imbalance and starch hydrolysis is thus linked
to respiratory metabolism. which in turn would be linked to

lycopene development through considerations of the energy

59

requirements for its synthesis.

g; Blotchy Hipenigg

Because low seed density per locule was found to be
associated with blotchy ripening in a previous study. an
experiment was conducted to determine whether poor pollina-
tion.might influence low seed number per locule and the
incidence of blotchy ripening.

Procedure:

Glamour tomato plants spaced 4 by 5 feet were trans-
planted on May 28. 1964. into a field fertilized with 300
lbs. of 5-20-20 fertilizer and 100 lbs. of ammonium nitrate
per acre. On July 7. 1964. an additional 300 pounds per
acre of 12-12-12 fertilizer was applied as a side dressing.

.Attempts were made to induce uneven ovule fertiliza-
tion by the following methods: 1. flowers were emasculated
at the time of anthesis and the stigma was pollinated. then
after an hour delay a section of the stigma and style was
removed by making a vertical cut through the stigma and down
the style of the pistil: 2. treatment two varied slightly
from that of one in that a section of the stigma and style
were cut away four hours after pollination rather than one
hour after pollination: 3. the stigma was pollinated on only

one side with pollen that had been collected on a very narrow

60
spatula.

According to Cooper (27) dehiscence of tomato stamens
begins 24 to 48 hours after the opening of the corolla. so
only flowers that were in the first stages of opening were
selected for treatment in order to prevent natural self-
pollination. Gelatin caps were placed over treated flowers
to keep them from being chance pollinated. The first pistils
were cut and pollinated on July 10. 1964. and the last treat-
ments were made on July 23. 1964.

Five tomato plants were used in each treatment. and
each treatment was replicated twice. Twenty flowers per
plant were treated and then tagged for further observation.

Two moisture levels were used. A small rotary
sprinkler with a 1/16 inch orifice manufactured by the Rain
Bird Company was put in Operation on bright. hot days to
increase the relative humidity and lower the plant's poten-

tial transpiration rate.

Results and Discussion:

The various pollination treatments definitely influ-
enced the number of treated flowers that ultimately produced
mature fruits. Sixty-five percent of the flowers that had
only a portion of their stigmatic surface pollinated and had
no section of the style or stigma removed produced mature
fruits (Table 16). The stigmas and styles of flowers that

were cut at one and four hour intervals after hand pollination

61

TABLE l6.--The Influence of various Methods to Induce Uneven
and/or Poor Pollination Upon the Incidence of Blotchy

Ripening.

 

‘—
L

 

 

 

 

 

Sprinkled Non-Sprinkled Average
Treatment After Percent Percent Percent Percent Percent
Flower Fruit Blotchy Fruit Blotchy Blotchy
Emasculation Set Fruit Set Fruit Fruit
Pollinated only
i of stigma 64 48 65 42 45.2 a
Stigma Pollin-
ated. then out
after 4 hours 46 44 44 38 41.2 a
Stigma Pollin-
ated. then out
after 1 hour 35 33 37 30 31.5 b
Control 88 30 87 27 28.5 b

 

 

* Means with uncommon letters are significantly different at
5%'leve1.

62
produced a fruit set of 35 and 45 percent respectively
(Table 16). All treatments resulted in reduced fruit set
when compared to the percentage of fruit set by control
flowers which were allowed to pollinate naturally.

A possible reason for the low percentage of mature
fruit produced by flowers that were hand pollinated may be
that the removal of part of the stigma cone surrounding the
pistil resulted in a less favorable environment for pollen
germination. There was also a chance that the style was
damaged more than intended and this could have kept the
pollen tubes from fertilizing the ovules. Other factors
that could be involved in reducing the number of fruit set
are the quantity of pollen applied to the hand pollinated
flowers was less than that reaching the stigma under condi-
tions of natural self-pollination. and that an excess amount
of pollen was applied at times and was not spread out over
several applications (95).

The application of water to the treatments apparently
did not affect fruit set or the incidence of blotchy
ripening.

Flowers that had only a portion of their stigma pol-
linated and flowers that had sections of the stigmas and
styles removed four hours after pollination produced a higher
percentage of mature fruit affected with blotchy ripening
than did flowers from the remaining treatment or flowers from

the control plants (Table 16).

63

Seed density beneath normal and blotchy tissue was
determined. From a sample of 77 fruit. there was an average
of 40 seed/locule underlying normal tissue and only 28
underneath blotchy tissue.

A number of flowers that were unevenly pollinated
produced fruit that were not symmetrical. and it was observed
that the majority of the fruits that were not symmetrical
were affected with blotchy ripening on the flattened side
of the fruit. This relationship did not always occur and no
actual data was collected to substantiate the observation.
Nevertheless. it was found that blotchy surface areas were
associated with underlying areas of low seed density.

‘Although not all flowers that had been manipulated
produced non-symmetrical fruit or fruit affected with blotchy
ripening. flowers that had been manipulated in an effort to
induce poor and/or uneven pollination produced significantly
more fruits affected with blotchy tissue than flowers from
the control plants. Thus. these data suggest that areas of
low seed density. could possibly be caused by poor and/or
uneven pollination. and that such conditions could contribute
to the incidence of blotchy ripening.

Hudrjavcev (70) reported that reducing light intensi-
ties by 20 percent of full daylight when pollen mother cells
were at the tetrad stage caused a reduction in the fertility
of the flowers. According to Smith and Cochran (102) the
best range for tomato pollen germination is 70° to 85° F.

64
and the best temperature for maximum pollen tube growth
is at 70°F. Germination and growth were reported to be
very poor on either side of the optimum temperatures. From
these studies it appears that adverse weather conditions
could cause poor and/or uneven pollination early in the sea-
son. which could result in uneven seed distribution through-
out the fruit's locules and possibly contribute to the inci-
dence of blotchy ripening.

Kidson and Stanton (59) and Ells (35) have both
reported blotchy ripening to be most severe in the early
harvests. If adverse weather is a factor in the development
of blotchy ripening. it may be that fruit produced early in
the season are more likely to encounter periods of cloudy.
rainy weather or cool temperatures and are. therefore. more
likely to develop blotchy ripening. The possibility also
exists that flowers producing the early mature fruit are
more likely to be subjected to conditions that could adversely
affect pollination than flowers opening later in the season.
or a combination of both factors may produce blotchy ripening.

EFFECT OF CERTAIN CHEMICALS ON TRANSPIRATION

The influence of various chemicals that modify trans-
piration rates and might affect the rate of tomato fruit

growth and the incidence of blotchy ripening were studied.

Procedure:

The effect of the following chemicals upon transpira-
tion of the variety Moreton Hybrid were investigated: 1.
copper sulfate as a foliage spray (rate: 5 1bs./100 gal.).

2. octa-hexadecanol as a soil application (rate: 5 grams/5
inch clay pot). 3. octa-hexadecanol as a foliage spray (rate:
10$ solution by volume). 4. glycerol as a foliage spray
(rate: 10 ppm). and 5. control.

The plants were seeded on June 26 and transplanted
into 5-inch pots on July 12. Five plants per treatment with
two replications were used.

All plants were uniformly watered prior to application
of chemicals on August 24. 1962. Just before the plants were
treated and the pots sealed in polyethylene bags. enough
water was added to the pots so that some water drained out.
The amount of water transpired by the plants between weigh-
ings was expressed as a percent of the original weight. and
the differences in amount of water lost among treatments was
expressed as a percent of the control.

The temperature in the greenhouse during the first

65

66
day attained 110°F.. but on the second and third day the
temperatures were 70-75°F.. and the weather was overcast.
when the last weighings were made the lower leaves of the
plants had wilted. The glycerol concentration used in this
investigation caused the leaves to yellow indicating that

the concentration may have been too great.

Results and Discussion:

The glycerol application increased the rate of trans-
piration by approximately 3 percent. perhaps because of
foliage injury. The copper sulfate solution initially inhi-
bited transpiration. but after 29 hours slightly increased
it (Fig. 3).

Both acts-hexadecanol treatments decreased the
plant's transpiration rates. The transpiration rate of
plants treated with the foliage application averaged less
than 1 percent lower than the control. while the transpira-
tion rate of plants treated with the soil application.were
3 percent lower than that of the control plants (Fig. 3).

 

   

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INFLUENCE OF VARIOUS MOISTURE STRESSES ON THE INCIDENCE
OF BLOTCHY RIPENING

Because of difficulties encountered in regulating
soil moisture and atmospheric humidity levels in the field
during the summer of 1963. a study was initiated in the
greenhouse to further investigate the affects of different
moisture stresses upon the incidence of blotchy ripening.

In addition to studying the effects of soil and atmospheric
moisture levels the affects of nutrients were also included.
The purpose of this investigation was to induce blotchy
ripening by the use of a combination of several factors

that were suspect.

Procedure:

Glamour and Fireball varieties were seeded in flats
of vermiculite on January 4 and 8. 1964. respectively and
transplanted into four-inch pots on January 28. 1964.
Twenty-four plants of each variety were selected for uni-
formity of size and single plants were transplanted into
drums 2 feet in diameter and 2 feet high on March 12. 1964.
A 4 inch layer of pea-gravel was placed in the bottom of
each drum to facilitate drainage through holes in the side.

Each treatment consisted of four plants replicated
twice.

The following treatments were imposed: 1. high soil

68

69

moisture (80% available soil moisture-ASH) plus high humid-
ity surrounding the aerial portion of the plant. 2. inter-
mediate soil moisture (50% ASM) with normal greenhouse
environment. and 3. low soil moisture (20% ASM) in combina-
tion with infra-red heating. Heat was applied from 8:00 am
to 6:00 pm. The above treatments will be referred to as:
1. low moisture stress. 2. intermediate moisture stress or
control. and 3. high moisture stress treatments. Soil Keis-
ture levels were evaluated with Delmhorst soil blocks. and
average readings taken at 6 and 12 inch depths were used to
determine the time of irrigations.

The soil used was a mixture of six parts soil. two
parts sand. and three parts muck by volume. The soil mix-
ture contained the following quantities of active material:
120 lbs. nitrogen. 10 lbs. phosphorus. 227 lbs. potassium.
1200 lbs. calcium. and 48 lbs. magnesium per acre. The low
moisture stress plots were treated with 100 lbs. N from
calcium nitrate. and 240 lbs. of Ca per acre as calcium
chloride: the intermediate stress plots with 100 lbs. of N
as ammonium nitrate and 60 lbs. of K split evenly between
potassium chloride and potassium sulphate; and the high
stress plots with 100 lbs. of N per acre as potassium
nitrate. and 120 lbs. of K per acre as potassium sulphate.
All treatments received 120 lbs. of P205 per acre as double
super phosphate. The nitrogen in each treatment was applied
March 16. March 30. and April 9. 1964 at the rate of 40. 30.

70
and 30 lbs. per acre respectively.

Uniform watering was practiced until April 28 when
the various treatments were imposed. Plants growing under
low moisture stress received 78 liters. under intermediate
stress 119 liters. and under high stress 77 liters of water
per plant from April 30 to June 27 (Table 17).

High humidity was maintained in the low stress treat-
ment by confining 4 plant plots in a six-foot high open
polyethylene structure and misting from 8:00 am to 6:00 pm
with an automatic mister described in a previous study.
Water applied by misting compensated for only evaporational
losses as was indicated by the fact that only a trace of
water accumulated in collecting cans.

The yield of normal tomatoes. blotchy tomatoes. and
tomatoes affected with blossom end rot were recorded from
each treatment. Blotchy tomatoes were considered to be
those with more than 10 percent of their surface area affected
with blotchy tissue.

The percent dry weight of fruit and foliage tissue
from the different treatments was determined. Fruit samples
were dried at 135°F for 480 hours: plant tissue samples were
first air dried and then dried at 1500 for 48 hours in a
forced air oven.

Chemical analyses were made on fruit and plant tissue
from the different treatments for N. K. P. Na. Ca. Mg. Mn.

Fe. Cu. B. Zn. and Al. Nitrogen was determined by the

71

TABLE l7.--Water Use by Tomatoes as Related to Irrigation
and Treatment.

 

Liters of water used/plant

 

 

Treatmentl/ from Aprilgjo to June 22
20% ASE. Infra-red Heat 77

50% ASM. Nermal Greenhouse

Environment 119

80% ASM. Misted Enclosure 78

 

 

1/ Soil recharged to field capacity when ASM (available
soil moisture) fell to percent indicated.

72
Kjeldahl procedure. potassium with a flame photometer: and
other elements by a direct reading photoelectric spectro-
meter (58).
The analyses of variance were performed on the result-
ing data as indicated by Snedecor (103) and mean comparisons
made by the method described by Duncan (34).

Results and Discussion:

Enclosing the plants and misting increased the aver-
age relative humidity 15% and decreased light intensity. as
measured in foot candles. a maximum of 7 percent.

There were no differences in the number of fruit per
plant among the treatments. but fruit weight varied from
3.81 Kg. under high moisture stress to 5.44 Kg. per plant
under the intermediate moisture stress treatment (Table 18).
Fruit on plants grown under low moisture stress conditions
were 40 percent larger than those grown under high stress.
However. the percent soluble solids of fruit from the high
moisture stress were 38 percent higher than were percent
soluble solids of fruit from low moisture stress plots: and
both the percentage dry weight of the fruit and the per-
centage dry weight of the foliage tissue produced under the
high moisture stress treatment was higher than under low
and intermediate moisture stress (Table 18).

Differences among the three classes of fruit (normal.

blotchy. and blossom-end rot) were found. 83 percent of the

73

TABLE l8.--The Influence of Moisture Stress Upon Fruit
Number. Fruit Weight. Average Fruit Weight. Soluble
Solids. Dry Height of Fruit and Foliage Tissues of Tomato
varieties Fireball and Glamour.

 

 

Moisture Stress

 

 

 

 

__ng Intermediate High
NO. Fruit/Plant 52.5 a 62.9 a 56.0 a
1&2“): “It/Plant 5.0 a 5.4 a 3.8 b
Avg. Fruit Wt. (g.) 95.3 a 86.3 a 68.1 b
Soluble Solids % 4.5 b 5.1 a 6.2 a
% Dry Nt. of Fruit 6.2 b 6.8 b 8.6 a
5 Dry Wt. of
FOliage 11.8 b 12.7 b 15.4 a

 

 

* Means with uncommon letters are significantly different
at the 5% level. Letters refer only to values in the
same horizontal column.

74
fruits produced by plants subjected to the low moisture
treatment were classed as normal. 16 percent as blotchy and
1 percent as being affected with blossom-end rot on a fruit
weight basis (Table 19). Percentage values based on either
number or weight of fruit from each class were similar. On
a number basis it was found that 84 percent. 14 percent.
and 1 percent of the fruit from low moisture stress plots
were classed as normal. blotchy. and blossom-end rot respec-
tively (Table 19).

Plants grown under the intermediate moisture stress
produced significantly more fruit classed as normal than
were produced by plants grown under the other two treatments.
Percentage values. by weight. of the different grades of
fruit from plants grown under intermediate stress conditions
are as follows: 90 percent of the fruits were normal. 20
percent blotchy. and 8 percent were affected with blossom-
end rot (Table 19). Percentages based on number gave nearly
the same values for each class as fruit weight. There was
no significant difference in weight of fruit classed as
blotchy. and fruit classed as being affected with blossom-
end rot within the intermediate moisture stress treatment
(Table 19).

within the high moisture stress treatment. fruit con-
sidered to be normal accounted for 77 percent. fruit with
blossom-end rot 22 percent of the total. and blotchy fruit
1 percent of @he total on.a fruit weight basis. The percentage

75

TABLE l9.--The Influence of Moisture Stress Upon the Number
and Weight Per Plant of Blotchy. Nbrmal. and Fruit Affected
with Blossom-End Rot.

 

‘— I
—: —

New

 

 

 

 

 

 

Low ~ Intermediate High

Fruit Class 2 $ .£__
Norma :

Ht./Plt. (Ks.) 4.22 83 4.95 90 2.95 77
No./P1t. 44.3 84 57.8 92 45.4 81
Avg. Frt. Ht. (8.) 95.3 86.2 63.5
Blotchy:

Ht./P1t. (Kg.) 0.82 16 0.09 2 0.04 1
No./P1t. 7.5 14 0.8 1 0.5 1
Avg. Frt. Ht. (g.) 108.9 113.5 113.5
Blossom-End Rot

Ut./P1t. (Kg.) 0.04 l 0.41 8 0.82 22
No./P1t. 0.6 l 4.2 7 10.0 18
Avg. Frt. wt. (g.) 77.1 95.3 81.7

 

 

L.S.D. for differences among fruit class mean.weight/p1ant
for the same moisture stress treatment: L.S.D. - .56
K3./plant. .05

L.S.D. for differences among moisture stress treatments for
fruit weight/plant at the same fruit class level: L.S.D. =
.48 Kg./plant. .05

76
values of each class of fruit on a number basis was 81 per-
cent normal. 18 percent classed as having blossom-end rot.
and 1 percent of the fruit were blotchy (Table 19).

Blotchy fruit were found to be slightly. but con-
sistantly heavier than normal fruit or fruit affected with
blossom-end rot. The weight of blotchy fruit averaged 108.9.
113.5. and 113.5 grams per fruit for the low. the intermedi-
ate and the high stress treatments respectively. as compared
to weight of fruit classed as being normal. which averaged
95.3. 86.2 and 63.5 grams per fruit. and those classed as
having blossom-end rot which averaged 77.1. 95.3. and 81.7
grams per fruit for the three respective treatments low.
intermediate and high moisture stress (Table 19).

A significant interaction between the three classes
of fruits and the three treatments was found to exist.
Plants subjected to conditions conducive to low moisture
stress produced significantly more fruit. on a fruit weight
basis. classed as blotchy than plants subjected to the inter-
mediate and high moisture stress treatments. There was no
significant difference in fruits classed as blotchy between
intermediate and high moisture stress treatments. On the
other hand. plants growing under conditions conducive to
low moisture stress produced significantly less fruit
affected with blossom-end rot than was produced by plants
subjected to the conditions conducive to high plant moisture
stresses (Table 19).

77
The correlation between soluble solids of tomato

fruit and tomato fruit weight was determined for fruit from
both varieties. A highly significant negative correlation
coefficient (r = -,740) between fruit weight and percent
soluble solids of tomato fruit from the variety Fireball was
found. The amount of change in percent soluble solids asso-
ciated with a change in fruit weight is shown in Figure 4.
There was no significant correlation between fruit weight
and percent soluble solids of fruit from the variety Glamour.

Mineral analyses showed that fruit taken from plants
grown under low moisture stress removed significantly more
phosphorus than fruits taken from intermediate or high mois-
ture stress treatments (Table 20). The amount of calcium
removed by fruits taken from plants grown under conditions
conducive to high moisture stress was significantly less
than the amount of calcium removed by fruits from plants
subjected to the other treatments.

There were highly significant differences among all
treatments in the amount or zinc removed by tomato fruits.
Fruits grown under low moisture stress removed the most zinc.
followed by fruits from plants subjected to intermediate
moisture stress. which removed slightly less zinc. Very
little zinc was removed by fruit from plants grown under
conditions conducive to high moisture stress (Table 20 and
21).

Plants grown under low moisture stress removed

78

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79

TABLE 20.--The Influence of Moisture Stress Upon the Average
Amount of Minerals Accumulated in the Fruit and Foliage
Tissue of Both Fireball and Glamour Tomato Plants.

 

Minerals

EQ'URZ

ng9§§§

ES'UNZ

988?

Zn
A1

 

Moisture Stress

 

 

 

 

row Wat's use...

MA FRUIT MINERAL COMPO I ION
(values expressed in grams/plant)

11.3 a 13.3 a 10.7 a

19.6 a 19.9 a 17.6 a
1.3 a 1.0 b 0.8 b
0.5 a 0.5 a 0.2 b
0.8 a 0.6 a 0.5 a
(values expressed in milligrams/plant)

225.0 a 133.0 a 178.0 a
7.0 a 7.0 a 5.0 a
25.0 a 18.0 a 15.0 a
2.5 a 1.2 a 1.5 a
5.2 a 4.0 a 3.7 a
1.2 a 0.5 b Trace
6.0 a 7.0 a 6.0 a

TOMTO EOLIAGE MINERAL COMPOSITION

(values expressed in grams/plant)
2.9 a 4.1 a 3.3 a
3.7 a 4.8 a 4.5 a
0.4 a 0.3 b 0.3 b
17.1 a 15.6 b 9.3 b
2.4 a 3.0 a 2.0 a
(values expressed in milligrams/plant)

210.0 a 110.0 b 75.0 b
19.0 a 25.0 a 20.0 a
54.0 a 52.0 a 32.0 b

4.5 a 3.5 a 3.0 a
6.5 a 7.5 a 4.5 b
28.0 a 10.5 b 5.7 b
34.0 a 51.0 b 30.0 b

 

 

 

* Means with uncommon letters are significantly different at

the 5% level.

Letters refer only to values in the same

horizontal column.

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82
significantly more P. Na. Ca. Zn. and Al than plants grown
under intermediate and'high moisture stress treatments.
Significantly more iron and boron were taken up by plants
grown under the low and intermediate moisture stress treat-
ments than plants subjected to the high moisture stress
treatment (Table 20 and 21).

Transpiration as well as soil moisture appeared to
influence the incidence of blotchy ripening and blossom-end
rot. Although the amount of water required per plant from
low and high moisture stress plots was nearly the same
(Table 17). The ASM of low moisture stress plots did not
go below 80 percent. while the ASM of high moisture stress
plots dropped to 20 percent. The difference in ASM between
low and high moisture stress plots was because of relatively
different transpiration rates of plants from the respective
plots. Significantly more blotchy fruit were produced on
plants from the low moisture stress plots. associated with
low rates of transpiration. and significantly more fruit
with blossom-end rot came from high moisture plots. associ-
ated with higher rates of transpiration. than were found to
be produced on the intermediate moisture stress plots
(Table 19).

The accumulation of more water in the fruits of plants
grown under low moisture stress conditions is indicated by
their larger size. less dry weight. and lower soluble solids
(Table 18). This could predispose the plants to blotchy ‘

83
ripening.

Thus. in this experiment where soil moisture and
atmospheric conditions surrounding the aerial portion of the
plants could be modified more easily than in the field. a
higher percentage of fruits were affected with blotchy ripen-
ing under conditions of low moisture stress than under condi-
tions of high moisture stress. As the soil moisture tension
increased and transpiration increased. the percentage of
fruit affected with blotchy ripening decreased. while the
percentage of fruit affected with blossom-end rot increased.

various workers have previously indirectly indicated
that transpiration rates can influence the incidence of
blotchy ripening. Gilbert (41). observed the absence of
vascular browning with an increase in air movement from the
trade winds in the Hawaiian Islands despite the occurrence
of cloudy. wet weather. Gilbert postulated that injury was
from sub-oxidation. but the winds may have increased the
transpiration rates to the point where not as much water was
accumulated in the fruit. which in turn probably lessened
the chances for blotchy ripening development.

Korbonits (69) found that the dry matter content of
tomato fruits was highest from plants grown on drier. heavier
loans than those grown on soils with high moisture content.
He also found periods of rainy weather reduced the dry matter
content of tomato plants and fruit. As found in this study
and supported by others (60. 77). plants that produced fruit

84
of low dry matter content are associated with the production
of blotchy fruit. and blotchy fruit themselves have been
shown to be lower in dry matter content than normal fruit
(14). Thus. blotchy fruit are associated with low dry matter
content. and Korbonits (69) describes conditions under which
fruit of low dry matter are produced. These data indirectly
suggest that blotchy ripening is associated with high soil
moisture levels and low transpiration rates.

Kidson (62) in working with tomato plants grown in
solution cultures. concluded that high humidity did not
influence cloud provided there was adequate light. This work
also suggests that transpiration influences the production of
blotchy ripening. High humidity in combination with low
light intensities would definitely tend to reduce transpira-
tion (32). However. high humidity in combination with high
light intensity could increase transpiration by heating the
leaves of the plant. It may be that high light intensity.
even in the presence of high humidity. enhanced transpiration
enough to prevent an excessive amount of water from being
incorporated into the tomato fruit or increased carbohydrate
accumulation.

Data presented by Clay and Hudson (17) also supports
the hypothesis that high moisture stresses reduce the inci-
dence of blotchy ripening. They report that very few blotchy
fruit were found on plants growing on soils of high salinity.

From the data obtained in this investigation it appears

85

that blossom-end rot tends to be more prevalent under condi-
tions conducive to high moisture stress. A very small per-
centage of the fruit produced by plants grown under condi-
tions of low moisture stress were affected with blossom-end
rot. while 22 percent of the fruit from plants subjected to
relatively higher moisture stresses were affected with the
disorder (Table 19).

Several workers have indicated that low calcium levels
cause blossom-end rot. and recommended liming the soil or
applying calcium foliage sprays to correct the disorder (38.
79. 36. 104. 91). The calcium values of fruits and foliage
from the high moisture stress treatment. which produced the
highest percentage of fruit affected with blossom-end rot.
were significantly lower in calcium content than fruits and
foliage of plants grown under the intermediate and low mois-
ture stress treatment (Table 20). There was no additional
calcium added to either the intermediate moisture stress
treatment plots or to the high moisture stress plots. Thus.
the low calcium values for fruit from the high moisture
stress treatment may have been induced either by conditions
conducive to high transpiration or to high K fertilization.
and the low quantities of Ca. may only be associated with
the incidence of blossom-end rot rather than being the cause
of it. Walsh and Clarke (111) also concluded that low cal-
cium content of the fruit by itself does not result in the

disorder.

86

Other work also implies that high soil moisture ten-
sions and/or high transpiration rates could promote blossom-
end rot. Hardh (46) suggested that the initial cause of
blossom-end rot was a change in enzyme activity due to an
abnormal increase in soil and plant concentration. Such con-
ditions could come about because of low available soil mois-
ture levels and/or excessive transpiration. Hulea (54) con-
cluded that blossom-end rot was not caused by bacteria. but
by defective water uptake occasioned by climatic or edaphic
conditions. Nesterhout (112) found that calcium deficiency
in the plant did not always produce blossom-end rot and
suggested that some other factors are involved in the develop-
ment of the disorder. Kidson (63) found that an increased
osmotic concentration of a nutrient solution resulted in a
reduction in the calcium level in the leaves of tomato plants.
and Geraldson (38) noted that excessive total salts can cause
calcium deficiency. Wilson (115) supports the idea that low
available soil moisture levels are conducive to the develop-
ment of blossom-end rot.

All of the above findings support the hypothesis that
tomato plants grown under a high moisture stress tend to pro-
duce fruit affected with blossom-end rot and that calcium
deficiency by itself may not be the sole cause of it.

The different nitrogen sources and amounts of potas-
sium applied to the three different treatments in this study
apparently had no significant affect on the amount of these

87
elements accumulated by the plants and fruits (Table 20).
The low. high. and intermediate moisture stress treatments
received the same quantity of phosphorous. but plants and
fruits subjected to the low moisture stress treatment accumu—
lated significantly more phosphorous than plants subjected to
the other treatments (Table 20).

Although the low moisture stress treatment received a
large amount of calcium. there was apparently ample calcium
already available in the soil. as indicated by the fact that
the amounts of calcium found in tomato fruit and foliage tis-
sue from the low moisture stress treatment and the amount of
calcium found in fruit and foliage tissue from the intermedi-
ate moisture stress treatment were not significantly different.

The relative amounts of calcium and sodium accumulated
by tomato plant foliage and fruit under conditions conducive
to high moisture stress agree with data presented by Kidson
(66. 67). He found that increasing the osmotic pressure of
nutrient solutions. in which tomato plants were grown.
resulted in reductions in the amount of calcium in the leaves
and a ten-fold rise in the sodium content. Kidson (66) found
that the high osmotic concentrations of a nutrient solution
was accompanied by reduced incidence of cloud. just as the
high moisture stress treatment was accompanied by a reduced
incidence in blotchy ripening (Table 19).

Fruit and plant tissue from the low moisture stress

treatment contained significantly more zinc than plants and

88
fruit tissue from the intermediate and high moisture stress
treatments (Table 20). Kidson (63) found that when fruit
ripened under conditions inducing cloud there was an indica-
tion that applications of 0.05 ppm of zinc was associated
with increased severity of cloud symptoms. The low moisture
stress treatment was associated with an increased amount of
blotchy ripening (Table 20) and was associated with tomato
fruit and foliage tissue with higher zinc concentrations even
though no additional zinc was added. No direct cause and
effect relationship was established between mineral composi-
tion and the incidence of blotchy ripening. It appears more
likely that the conditions that contribute to the incidence
of blotchy ripening also affects the mineral composition of
tomato foliage and fruit rather than mineral composition
directly inducing blotchy ripening.

Thus. the data already presented in the pollination
study along with the data from the seed density determinations
underlying normal and blotchy locules suggest that poor pol-
lination and unequal distribution of seed in the fruit are
associated with development of blotchy ripening. The moisture
stress to which tomato plants are subjected also appears to
play an important role in the development of blotchy ripening.
It could well be that both poor pollination and conditions
conducive to low moisture stress contribute to the development

of blotchy ripening.

GENERAL DISCUSSION AND CONCLUSIONS

The objective of this investigation was to evaluate
factors that might be associated with blotchy ripening in
tomato fruit. Inducing the disorder might result in a better
understanding of factors that cause it. After reviewing the
literature it was suspected that water relations or inade-
quate quantities of carbohydrates for fruit development were
responsible for blotchy ripening. A series of experiments
were devised to induce the disorder by manipulating the
water relations of the plant and by attempting to lower the
quantity of carbohydrates for fruit production by reducing
light intensities.

Data from these investigations suggest that both
available soil moisture and amount of water lost by the plant
through transpiration influences dry matter content. percent
soluble solids. and percentage of fruit with uniform pig-
mentation. Conditions conducive to low transpiration rates
in combination with high levels of available soil moisture
favored development of blotchy ripening.

Information pointing to the role of low evaporation-
high soil moisture levels in promoting the development of
blotchy ripening may be found in reports where rainy. cloudy
weather (59. 55. 56. 44. 63) was associated with development
of blotchy fruit. These findings were interpreted as being

89

90
associated with reduced transpiration that could upset the
plant ' 3 water balance.

Nhen.available soil moisture levels were allowed to
drop to 20 percent in combination with conditions conducive
to high rates of transpiration. there was less incidence of
blotchy ripening. Lower levels of soil moisture appeared
to be associated with less blotchy ripening. High fertilizer
application rates (120. 121. 105. 90. 71). reported to have
reduced blotchy ripening. may have influenced the water
balance of the plant by increasing the osmotic concentration
of the soil. These fertilizer practices would tend to
reduce the disorder by reducing the amount of water available
to the plant.

Reduced light intensities usually accompanying rainy.
cloudy weather cannot be completely ignored as contributing
to blotchy ripening through their affect on photosynthetic
activity. Reduced photosynthesis may be a factor contribu-
ing to the incidence of blotchy ripening. but water balance
of the plant is still thought to be the dominate factor
associated with its occurrence. Light intensities on the
low moisture. the intermediate. and the high moisture stress
treatments were nearly the same. but more blotchy fruit were
produced by plants grown under low moisture stress conditions
than under intermediate or high moisture stress conditions.

Although other reports have indicated that shading
increased blotchy ripening (124. 118. 57) and that removal

91
of part of the fruit from the plant reduced the disorder
through less competition for carbohydrates (30). they were
not found to influence the development of blotchy ripening
in these studies.

Data collected in these studies suggest that blotchy
ripening and blossom-end rot are caused by moisture imbal-
ance. blotchy ripening appearing more frequently under low
moisture stress conditions and blossom-end rot being more
prevalent under high moisture stress conditions. Similar
findings have also been reported by Carolus et a1. (14).

Investigations conducted by Butters (12) and Carolus
et a1. (14) illustrate differences in severity of blotchy
ripening and the difference in quantity of water required to
produce a crop during different years. In taking these
studies into consideration plus the sporadic occurrence of
blotchy ripening. it appears as if a complex of factors may
contribute to the development of blotchy ripening.

Blotchy tissue was associated with underlying areas
of low locular seed density. Because seeds are an important
source of diffusable auxins. lower seed numbers might be
linked to lower auxin levels beneath blotchy tissue. SkOOg
and Robinson (102). Audus (3). and Mitchell et a1. (82) have
indicated that lower auxins levels are associated with less
transition of polysaccharides to sugars. White (114) indi-
cated that blotchy tissue was associated with decreased starch
hydrolysis and sugar content. and E113 (35) found soluble

92

solids content of juices from blotchy tissues to be lower
than those from non-blotchy tissues. The results of E118
and White suggest that starch was not being broken down to
sugars in blotchy tissue. Iow seed numbers. through auxin
imbalance and less starch hydrolysis could be linked to
lower respiratory metabolism. which in turn could be linked
to lycopene development through consideration of the energy
requirements for pigment synthesis.

Data from studies where pollen was placed on one
side of the stigma. or a section of the stigma and style
was removed shortly after pollination indicated that these
practices induced more blotchy fruit than were produced on
control plants. These results suggest that poor pollina-
tion early in the season. possibly caused by adverse weather.
may influence the concentration of blotchy areas by lowering
seed numbers in some locules. The lower seed number could
in turn influence the expression of blotchy ripening through
the development of an auxin imbalance within the fruit.

Several reports indirectly suggest that environmental
conditions early in the season could be involved in the
expression of blotchy ripening (35. 43. 59. 35). and indi-
cated that it was more prevalent during the earlier harvests.
Flowers that produced the early fruit would be more likely
to encounter adverse weather and would be most likely
to be poorly pollinated. The possibility also exists that
the first fruit harvested would also be most likely to

93
encounter adverse weather near the time of ripening. Thus,
weather conditions could affect some process other than
fertilization nearer the time of color development (18, 92,
97).

If poor pollination does influence the incidence of
blotchy ripening, by reducing seed number in certain locules,
it may be that this alone will not induce the disorder. As
already indicated, conditions conductive to lower moisture
stress are associated with the incidence of blotchy ripening.
It may be that fruits with low seed numbers in certain locules
must encounter conditions conducive to low moisture stress,
such as cloudy, rainy weather sometime after pollination in
order for blotchy fruit to appear. Blotchy ripening may not
appear on fruit with locules of low seed number if growing
conditions are favorable throughout the season.

However, if fruits having some locules of low seed num-
ber encounter unfavorable weather conditions, these areas
either may not be able to obtain needed materials for pigment
development, possibly because of translocation interference
(98), or such areas cannot utilize material already available
(31, 48, 49, 50, 51, 64).

The interaction of low locular seed number and condi-
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