Table Of ContentFACTORS AFFECTING THE ASCORBIC ACID
CONTENT (VITAMIN C) OF TOMATOES
BY
HUSSEIN HOSNY HASSAN
B.Sc, Fouad First University, Egypt, 1940
M.S., Maryland University, 1947
THESIS
SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN HORTICULTURE
IN THE GRADUATE COLLEGE OF THE
UNIVERSITY OF ILLINOIS. 1960
URBANA. ILLINOIS
UNIVERSITY OF ILLINOIS
THE GRADUATE COLLEGE
May 3, 1950
I HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY
HUSSEIN HOSNY HASSAN
SUPERVISION BY.
FACTORS AFFECTING THE ASCORBIC ACID CONTENT (VITAMIN C)
ENTITLED
OF TOMATOES
BE ACCEPTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR
THE DEGREE DOCTOR OF PHILOSOPHY
0F
fl 'U ' ' In Charge of Thesis
HHeeaadd ooff DDeeppaarrttmmeenntt
Recomtnendation concurred inf
Committee
on
Final Examination!
t Required for doctor's degree but not for master's.
M440
TABLE OF CONTENTS
Page
1
I. INTRODUCTION
1
II. REVIEW OF LITERATURE
10
III. MATERIALS AND METHODS
12
IV. EXPERIMENTS AND RESULTS
1. Variation in the Ascorbic Acid Content of
12
Shaded and Unshaded Fruits.
2. Effect of Solar Illumination on the Ascorbic
acid consent of Tomato Fruits at Various
16
Stage8 of Development.
16
a. Experiment 1
b. Experiment 2 17
18
c. Experiment 3
d. Experiment k 19
20
e. Experiment 5
f. Experiment 6 23
g. Experiment 7 25
3. Effect of Bagging on Fruit Development 27
J+. Greenhouse Experiments 30
a* Experiment 8 30
b. Experiment 9 32
5. Seasonal Variation in Ascorbic Acid Content 3^
6. Seasonal Variation in Number of Exposed
and Shaded Fruits 38
TABLE OF CONTENTS
(Continued) Page
V. DISCUSSION *H
VI. SUMMARY ^6
VII. ACKNOWLEDGMENT **7
VIII. LITERATURE CITED 48
IX. ILLUSTRATIONS 5^
X. VITA 61
i
INTRODUCTION
The tomato (Lycopersicon esculeatum var. commune)
Is important as a food primarily because of its ascorbic
acid (vitamin C) content. Efforts to increase the ascorbic
acid content of commercial varieties by breeding have not
been too successful, even with genetically superior strains
available. The slow progress in increasing the antiscorbutic
value of tomatoes has been due primarily to the difficulty of
comparing strains because of errors in sampling. This is
indicated by the highly variable and conflicting data in the
literature. The purpose of this study is to evaluate some
of the factors affecting the ascorbic acid content of tomato
fruit 8 in an effort to reduce sampling errors a,nd increase the
accuracy of strain comparisons.
REVI3W OF LITERATURE
The literature dealing with the ascorbic acid
content of tomatoes has been well reviewed by Maclinn and
Fellers (33) Hamner, and Maynard (15). and Xberg (l).
For this reason an attempt will only be made to cite
representative investigations,
Maclinn, Fellers, and Buck (32) reported on the
ascorbic acid content of 98 tomato varieties grown in
(l) Numbers in parenthesis refer to literature cited.
-2-
MassachusettB in the same soil at the same time. They found
variations among the varieties from 44 - .03 to 13 - .03
milligrams per 100 grams of fresh weight. They also reported
the existence of great variations among samples of the same
variety. For example, they gave values for the Bonny Best
ranging between 19 to 5° milligrams and for the John Baer
between 19 to 4tf milligrams per 100 grams fresh weight. They
listed the Marglobe to contain 28 per cent more ascorbic acid
than the Prichard variety. On the other hand, Tripp,
Satterfield, and Holmes (54), in a varietal test in North
Carolina, reported the Prichard variety to be high in ascorbic
acid content and to contain 2? per cent more ascorbic acid
than the Marglobe variety. Hamner, Bernstein, and Maynard (17)
presented data shovring wide variations in ascorbic acid content
of tomato varieties grown at different locations. They indicated
that fruits of Marglobe varied from 1^.4 ± 2.12 to 30.6 * 2.04;
Rutgers from 8.1 ± 0.50 to 19.7 * 1,17 and Pritchard, from 10.7 -
0.88 to 29.0 - 1.29.
Although a number of investigators (6, 11, 37, 50,
57, 58) have reported definite varietal differences in the
ascorbic acid content of tomatoes and other crops, Currence (9)
with samples obtained from a replicated field experiment
showed that differences between tomato varieties were indefinite
and difficult to demonstrate statistically.
-3-
Breeding for tomato varieties with high ascorbic
acid content, Shivrina (47) reported ascorbic acid values as
high as 43 milligrams per 100 grams fresh weight for cultivated
varieties and values as high as 80 milligrams per 100 grams of
fresh weight in some wild varieties. In 1938. Biryukov (4)
crossed varieties of tomatoes of high and low potencies and
found the first generation to have an ascorbic acid content
close to the parent with the higher values. In 1942, Reynard
and Kanapaux (43), reported that single determinations on each
of 166 second generation plants from a Red Current tomato x
Marglobe cross showed that the ascorbic acid content in the
F2 ranged from about 9 to 42 milligrams per 100 grams fresh
weight while the parental lines had 42 and 16 milligrams
respectively.
The influence of chromosome number on the vitamin C
content of tomato fruits has been the subject of considerable
discussion in the literature. In 1933, Key (30) reported
that tomatoes of the same genetic constitution, whether
of diploid (twelve pairs) or tetraploid (twenty-four pairs)
contained equal quantities of ascorbic acid. Later in the
same year, Sansome and Zilva (45) reported that tomatoes with
tetraploid number of chromosomes contained twice as much
ascorbic acid as tomatoes from the diploid plants. In 1935t
McHenry and Graham (36) compared tetraploid with diploid fruits
-4.
and reported that the latter contained about 84 per cent as
much ascorbic acid as the former, a difference considerably less
than that reported by Sansome and Zilva (45). However, in another
report published in 1936, Sansome and Zilva (46) stated that they
were unable to record again such a great inequality between the
ascorbic acid contents of tetraploid and diploid forms as
they reported in 1933. They suggested as a reason for such a
divergence that an unknown factor or factors must have been
responsible for thot inconsistency. McHenry and Graham (36)
claimed that the differences reported between tetraploid and
diploid tomatoes were due to fruit size, as the tetraploid
tomatoes are usually smaller than the diploid tomatoes.
Considerable disagreement is found concerning the
relation between fruit size and the ascorbic acid content.
Maclinn, Fellers and Buck (32), as well as other investigators
(l2, 33t 54), reported no correlation between ascorbic acid
content and fruit size within a strain or a variety of tomatoes.
Hallsworth and Lewis (13) found a rapid and highly significant
increase of the ascorbic acid content with decreasing weight
(correlation coefficient -0.94) for tomato fruits less than
30 grams*, whereas the fruits of 30 grams or more gave a
nonsignificant coefficient of -0.03. Several investigators
(6, 36, 43) however, found ascorbic acid to be negatively
-5-
correlated with fruit size.
In 1937, Maclinn, Fellers, and Buck (32) reported
that degree of ripeness has no significant effect upon the
vitamin C content of fruits picked from six tomato varieties.
Conversely, in 1945, Lo Coco (31) reported that the ascorbic
acid content was found to be highest near and before the
ripening state and lowest in green or overripe tomatoes.
Conflicting reports have been published on
experiments dealing with the effect of soil fertility and
plant nutrients. Some investigators (10, 23, 24, 4l) have
found that high fertility was favorable to the vitamin C
accumulation in plants, yet others have noticed comparatively
little or no effect (2, 26, 48, 49). However, Virtanen (5b)
and Isgur and Fellers (25) reported evidence that the use of
properly balanced fertilizers decreased the ascorbic acid
content of plants grown under field conditions.
Hester and Kohman (20) reported that tomatoes
grown on Sassafras sandy loam soil were 44 per cent higher in
ascorbic acid than those on Edgemont stony loam. However, the
tomatoes on the former soil were grovm at Moorestown, New Jersey,
and those on the latter at Elverson, Pennsylvania and harvested
one month apart.
Kessler (29) found that overfertilizatlon of apple
trees with nitrogen depressed the ascorbic acid content of the
-6~
fruit and reported that it was possibly caused by the shading of the
fruit with the heavy foliage of the apple trees that received high
nitrogen. Recently, Jones and Parker (27) reported an overall
inverse correlation between nitrogen and ascorbic acid content
of naval oranges. They obtained with 0, 3, and 5 pounds nitrogen
per tree 83.0, 70.5. and 68.5 milligrams ascorbic acid per 100
milliliters juice, respectively. However, Burrell, Brown and
Ebright (?) found that high nitrogen or a complete fertilizer
favored high ascorbic acid accumulation in cabbage,
Hester (21) stated that application of potassium
fertilizer to certain soils resulted in an increase in the
yield and in the vitamin C content of tomato fruits. He also
reported similar effects for the application of manganese to
soils deficient in this element (22). Hamner, Lyon and Hamner (l4)
showed that the ascorbic acid content of the tomato fruit was
not affected to any appreciable extent by wide variations in the
supply of macronutrient elements supplied to the plant.
Murphy (39) reported that environmental agencies
markedly influence the synthesis of vitamin C in tomatoes. She
stated that geographical situation is not a contributing factor
except insofar as environmental conditions are consistently
characteristic of that situation. Hamner, Lyon and Hamner (l4)
working with the Bonny Best variety reported that the location
where the crop is grown has an effect upon the ascorbic acid
