The Influence of Calcium on the Growth, Yield,
Quality, and Chemical Composition of
Watermelons, Citrullus vulgaris Schrad.
By
WILLIE ESTEL WATERS
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
January, I960
ACKNOWLEDGEMENTS
The author wishes to express his sincere apprecia-
tion to Dr. V. F. Nettles, Professor of Vegetable Crops,
for guidance and suggestions throughout this study.
The helpful advice and assistance of the other mem-
bers of the supervisory committee. Dr. W. 0. Ash, Dr. F. S.
Jamison, Dr. D. F. Rothwell, and Dr. B. D. Thompson, is
gratefully acknowledged.
Appreciation is expressed to all members of the
Vegetable Crops Department for their interests and coopera-
tion during this study.
The author is also indebted to his wife, Mary
Elizabeth Waters, for assistance in the preparation of
the manuscript and for continued devotion and encourage-
ment.
ii
CONTENTS
Page
LIST OF TABLES v
LIST OF ILLUSTRATIONS Till
INTRODUCTION 1
REVIEW OF LITERATURE 3
Mineral Nutrition of Cucurbits .......... 3
Effects on Yield ..... 3
Effects on Quality 5
Effects on Sex Expression and Fruit Set. ... 7
Effects on Blossom-end Rot •• 8
Calcium In Plant Nutrition ..... 10
Role in the Soil 10
Role in Plants 11
Cations in Plant Tissue ............. 13
Cation Accumulation ..••• 13
Effects of Nitrogen on the Cation Content • . 17
Distribution of Cations in Plants 18
METHODS AND PROCEDURES 20
Greenhouse Phase .......... 22
Field Phase 25
Description of Soil Type and Soil Test .... 25
Field Methods 26
Tissue Samples .......... 28
Chemical Analyses ...... 29
Statistical Methods . 30
RESULTS OF EXPERIMENTS 31
Greenhouse Phase 35
ill
Page
Growth Responses ........ 35
Sex Expression and Fruit Set ......... 42
Chemical Composition ••••••••••••• 45
Field Phase 48
Soil Tests 48
Growth Responses 50
Fruit Set 56
Chemical Composition . . . • 57
DISCUSSION 69
Growth Responses . . . 69
Sex Expression and Fruit Set 77
Chemical Analyses ...«• 78
SUMMARY AND CONCLUSION 84
REFERENCES CITED 90
APPENDICES 97
A - Detailed Soil Test Results "by Plot 97
B - Analyses of Variance Tables • 100
BIOGRAPHICAL NOTES Ill
iY
LIST OP TABLES
Table Page
1. Calcium levels in greenhouse solution cultures • 23
2. The composition of the basic nutrient solution
for greenhouse experiment. ......... 24
3. Total bi-monthly rainfall recorded at the
Horti culture Unit March 1 to June 30, 1959 . 27
4. The percentage of calcium, potassium, magnesium,
and sodium at six locations within mature
watermelon plants, 1958 • 33
5. Test of significance for the percentage of
potassium, calcium, and magnesium at six
locations within mature watermelon plants. • 34
0. The effects of calcium treatments on the dry
weight of vines, roots, fruits, and total
weight in the greenhouse experiment .... 42
7. The effects of calcium treatments on flower
production and fruit set in the greenhouse
experiment 43
8. Test of significance for the effects of calcium
treatments on flower production in the
greenhouse experiment . 44
9. The effeots of calcium treatments on the per-
centage of calcium, potassium, and magnesium
in the leaves and tips of plants grown in
the greenhouse . . . . 46
10. The effects of calcium treatments on the per-
centage of calcium, potassium, and magnesium
in the roots and fruits of plants grown in
the greenhouse ......... 47
11. The pH and pounds per acre of available nutrients
of samples taken from the watermelon beds on
April 1, 1959 48
Table page
12. The pfl and pounds per acre of available
nutrients of samples taken from each side
of the melon beds on April 1, 1959 49
13. The Influence of more than eight Inches of
rainfall on the removal of fertilizer
nutrients In pounds per acre from the
upper eight Inches of soil in watermelon
beds 50
14. The effects of calcium and nitrogen on early
vine growth as indicated by the dry weight
of eight hills per plot 51
15. The effects of calcium and nitrogen on the
number of early U. S. Number 1 watermelons • 51
16. Effects of calcium and nitrogen on the total
weight in pounds of early U. S. Number 1
watermelons 52
17. Effects of calcium and nitrogen on the total
number of U. S. Number 1 watermelons .... 53
18. Effects of calcium and nitrogen on the total
weight in pounds of U. S. Number 1
watermelons . . 53
19. The effects of calcium and nitrogen on the
average soluble solids as per cent sucrose
from all marketable melons per plot .... 54
20. The effects of calcium and nitrogen on the
average thickness of the rind in centi-
meters at the top center and bottom center
of all marketable fruits 55
21. The effects of calcium and nitrogen on the
average thickness of the rind in centi-
meters at the blossom-end of all marketable
fruits 55
22. The effects of calcium and nitrogen on the
percentage of blossom-end rot ....... 56
23. The effects of calcium and nitrogen on the
total number of fruits set . 57
24. The effects of calcium and nitrogen on the per-
centage of calcium, potassium, and magnesium
in the tips of young watermelon plants ... 58
vi
Table Page
25. The effects of Calcium and nitrogen on the per-
centage of calcium, potassium, and mag-
nesium in the leaves of young watermelon
plants ...... 59
26. The effects of calcium and nitrogen on the per-
centage of calcium, potassium, and mag-
nesium in the tips of mature watermelon
plants • 62
27. The effects of Calcium and nitrogen on the per-
centage of calcium, potassium, and mag-
nesium in the leaves of mature watermelon
plants . . . . 63
28. The effects of calcium and nitrogen on the per-
centage of calcium, potassium, and mag-
nesium in U. S, Number 1 watermelon fruits • 65
29. The effects of calcium and nitrogen on the per-
centage of calcium, potassium, and mag-
nesium in watermelon fruits exhibiting
blossom-end rot ,. 66
30. The average percentage of calcium, potassium,
and magnesium associated with each cal-
cium and each nitrogen level in both vines
and fruits from the field experiment .... 80
31. The pfi and the pounds per acre of available
nutrients from soil samples taken in
watermelon beds from all field plots on
April 1, 1959 98
32. The pH and the pounds per acre of available
nutrients from soil samples taken on each
side of the bed from all plots on April 1,
1959 ; . 99
33-42. Analyses of variance tables 101-110
vii
LIST OF ILLUSTRATIONS
Figure Page
1. The twelfth leaf from the base of the plants
In treatments 2, 3, 4, 7, and 8 from the
greenhouse experiment •• •••• 38
2. Representative- root systems from treatments
2, 3, 5, 7, and 8 of the greenhouse
experiment •••• 41
3. The interaction of calcium and nitrogen
(Cajj X Nl) on the magnesium content of
the leaves of young watermelon plants ... 61
4. The interaction of calcium and nitrogen
(Can X Nq) on the potassium content of
U. S. Number 1 watermelons ......
61
5. The interaction of calcium and nitrogen
(CaL X Nq) on the potassium content of
watermelon fruits exhibiting blossom-
end rot . 67
6. The interaction of calcium and nitrogen
(Ca^ X NL) on the magnesium content of
watermelon fruits exhibiting blossom-
end rot 67
7. The influence of calcium- on the dry weight of
fruits, roots, vines, and total weight per
experimental unit in the greenhouse .... 71
8. The percentage increase in early and total
yield of D. S. Number 1 watermelons from
plots receiving 500 and 1,000 pounds of
hydrated lime over plots receiving no
lime 73
viil
INTRODUCTION
The watermelon Is one of the most extensively grown
vegetables In the United States, yet little is known about
the nutrition of this plant. Florida alone produced 95,000
acres of watermelons during the 1957 and the 1958 seasons,
which comprised 31 per cent of tho southern acreage or 21
per cent of the acreage of the United States (80). Rela-
tively few basic nutrient experiments have been conducted
with watermelons, mainly because the extensive type of vine
growth limits the feasibility of greenhouse culture tech-
niques* However, extensive experimentation has been con-
ducted in the field on the rates, sources, and methods of
application of the major fertilizer elements.
In the South watermelons are planted on light sandy
soils, which often have Inherently low calcium supplies and
pH. Watermelons have generally been considered to tolerate
relatively acid conditions, and thus the liming of water-
melon fields is not normally a recommended practice. However,
from a literature review, it is obvious that very little
research has been conducted on the effects of differential
calcium levels and soil pH on the yield and quality of water-
melons •
The objective of this study was to evaluate the ef-
fects of the calcium supply on growth responses; yield;
2
quality; sex expression and fruit set; and the concentrations
of calcium, potassium, and magnesium in the tissues of the
Charleston Gray variety of watermelon. The study was con-
ducted in two parts: (1) a greenhouse phase involving eight
calcium levels in nutrient cultures and (2) a field phase
designed to study three levels of calcium in combination with
three levels of nitrogen.
The results of this study may be beneficial in ex-
plaining the occurrence of certain physiological disorders
and poor yields often obtained from watermelon fields re-
ceiving apparently adequate fertilizer. It also emphasizes
the need for additional research on the nutrition of the
watermelon.
REVIEW OF LITERATURE
Mineral Nutrition of Cucurbits
Effect 3 fin vleld
The extent to which the major nutrient elements
affect the yield of watermelons (Citrullus vulgaris Schrad.)
is variable, depending upon the element, the environment,
and the chemical properties of the soil. Hartwell and Damon
(34) reported in 1914 that the best yields of watermelons
were obtained on plots made very acid by the application of
sulfate of ammonia. Examination of their data Indicated
that liming had no effect on yield. Hartman and Gay lord
(33) reported no significant difference in yield or average
weight of watermelons grown on Princeton or Elk fine sand
ranging in pH from 4.7 to 7.5. However, there was a trend
toward greater yields at the higher pH levels. The pH
range was obtained by the application of up to 1,000 pounds
of elemental sulfur or up to 9,000 pounds of limestone.
Hall, Nettles, and Dennlson (28) found no significant
differences in yields in a factorial experiment on Arredonda
fine sand containing three levels of calcium (0, 80, and 160
pounds per acre supplied as calcium sulfate In the row) and
three levels of magnesium (0, 20, and 40 pounds per acre of
magnesium oxide applied in the row). Hall, Nettles, and
Dennlson (29) In later work were unable to show benefits from
3
4
the application of gypsum alone In the row. Jamison and
Nettles (40) reported that the application of soluble mag-
nesium with all Inorganic nitrogen increased the yields of
watermelons.
Elsenmenger and Rucinski (20) observed that calcium
hastened maturity of both watermelons and cantaloupes by
nearly two weeks over no-lime treatments. Apparently the
application of lime augments cantaloupe production on soils
with low pH. Carolus and Lorenz (14) concluded that the
application of lime to light acid soils promotes early ma-
turity and increases yields of muskmelons. Hartman and
Gaylord (32) obtained an increase of cantaloupes from 160
bushels to 350 bushels per acre by increasing the soil pH
from 4.7 to 7.2 with limestone. Other cucurbits including
cucumbers, squash, and pumpkins apparently yield more when
grown on soils moderately supplied with calcium and within
the pH range of 5.5 to 7.0 (42, 83).
Considerable research relative to the effect of N-P-K
fertilizers on yields has been reported. Hall, Nettles, and
Dennison (29) concluded after five years of experimentation
at several locations in Florida that 60 pounds per acre each
of potassium and nitrogen were ample to give maximum yields
in seasons with reasonably favorable rainfall. This is, in
general, supported by data presented by Nettles and Halsey(53)
in 1958. Bradley and Fleming (10) observed similar results
on Norfolk fine sand in Arkansas. They stated that 60 pounds
5
each of nitrogen, potassium, and phosphorus was adequate for
good yields. In a somewhat drier area in Texas, Smith and
Mohr (70) conoluded alter four years tests on Hockley fine
sand that 20 pounds of nitrogen, 40 pounds of phosphorus, and
40 pounds of potassium produced maximum yields. However,
Patterson and Smith (57) reported significant increases in
yield from up to 200 pounds of potassium on Hockley fine
sand in Texas. According to Brantley (11) nitrogen Increased
early marketable, total marketable, and total yield of water-
melons In Indiana on Princeton fine sand in a season of
heavy rainfall but not in a moderately dry season. Potassium
did not affect yields in either season.
Effgc^s qr quality
It has long been known that the quality of watermelons,
especially the soluble solids, is influenced by both heredity
and environmental factors (60, 85). The effects of these fac-
tors have been established; however, research relative to the
true influence of different nutrient elements is less apparent.
Hartman and Gaylord (33) reported that the application of up
to 9,000 pounds of ground limestone did not significantly in-
crease the percentage of sucrose. Hall, Nettles, and Dennison
(28, 29) observed that neither calcium sulfate nor magnesium
oxide had any significant effect on the percentage of soluble
solids, hollow-heart, or white-heart. However, Eisenmenger
and Kucinskl (20) stated that Cantaloupes and watermelons
grown on land treated with Calcium were considerably higher
6
in sugar content, although no data were presented. Mazaeva
(47) observed that magnesium increased the sugar content of
watermelons grown in pots of light sodpodzolized soil. Ac-
cording to Morazov (52) the application of sodium chloride
or sodium sulfate to the soil decreased the monosaccharides
and the total sugar content of both watermelons and musk-
melons.
Work by Brantley (11) and by Kimbrough (41) indicated
that up to 250 pounds of elemental nitrogen had no signifi-
cant effect on the percentage of soluble solids in water-
melons. Bradley and Fleming (10) reported a significant
increase in soluble solids as a result of an interaction be-
tween nitrogen and phosphorus and an interaction between
phosphorus and potassium, but other quality measurements such
as hollow-heart, white-heart, and rind thickness were not
affected by any fertilizer treatment. When yields were not
affected by fertilizer treatments, soluble solids were not
affected; therefore, they concluded that providing adequate
fertilizer assures good quality. In contrast to this. Hall,
Nettles, and Oennison (28) concluded after several experi-
ments that neither potassium nor nitrogen had any significant
effect on soluble solids, white-heart, or hollow-heart.
Brantley (11) found no effect from differential levels of
potassium on the quality of watermelons or cantaloupes.
Woodard (85) demonstrated that the occurrence of white-heart
of watermelons was associated with heredity and not with
nitrogen source.
7
Pffg<rtg fin ££& enreaginn and fruit set
The nature of the effect, if any, of the cation* on
sex expression and fruit set has not been clearly defined.
Hasler and Maurizio (35) reported that insufficient amounts
of potassium as well as nitrogen and phosphorus resulted in
both poor flowering and seed set in winter rape (Brassica
flajma). According to Mazaeva (47) , magnesium acts on repro-
ductive organs, tending to Increase female flowers in many
crops. Stark and Haut (72) found that flower production
in cantaloupes was inhibited when the potassium level was
dropped to 0.25 mllliequivalents per liter (9.15 ppm) .
There was a positive response of fruit set to high levels
of calcium: 10 and 15 mllliequivalents per liter (200, 300
ppm). A concentration of 0.2 mllliequivalents per liter
(2.4 ppm) of magnesium was inadequate for normal fruit set.
After comprehensive literature reviews on the
physiological aspects of sex expression, Loehwing (45) and
Heslop (36) concluded that, with the exception of carbohy-
drates and nitrogen, general nutrition Is not a major factor
in sex expression in monoecious and dioecious species.
Furthermore, Loehwing (45) stated that highly localized com-
positional differences are much more significant than general
composition, not only in relation to flowering but also in
determining sexes in various floral parts.
There are numerous reports in the literature to the
effect that increased nitrogen concentrations In the substrate
8
enhanced female sex expression in plants. Thompson (76)
working with spinach, Tibeau (77) with hemp, and Sahlnin (64)
with corn observed that high levels of nitrogen stimulated
the production of pistillate flowers while low nitrogen levels
favored stamlnate flower formation. Similar observations
have been reported by Tied j ens (78) and Dearborn (18) for
cucumbers (Cucumis sativus), by Hall (30) for gherkins
(Cucumis anguria) f by Sabinin (64) and Minina (51) for cu-
cumbers and watermelons, and by Brantley (11) for cantaloupes
and watermelons.
The Influence of nitrogen on fruit set is similar to
its effect on yields. In general. Increasing Increments of
nitrogen up to a critical maximum enhances fruit set while
additional increments tend to decrease fruit set (11, 17).
Work by Jamison and Nettles (40) and by Cunningham (17) indi-
cates that late side-dressing with nitrogen delays and de-
creases fruit set.
Effects on blossom-end rot
The precise cause of watermelon blossom-end rot has
not been determined. Blossom-end rot first appears as a
water-soaked area at the blossom-end, later turning brown,
and often invaded by saprophytic and parasitic fungi (56,
73). The disease has been attributed to many factors — includ-
ing pathogenio organisms, disarrangement of internal nutrition,
improper moisture supply, poor pollination and/or fertiliza-
tion. Pathologists (56, 75) have shown that a large number
9
of both saprophytic and parasitic organisms have been asso-
ciated with blossom-end rot. Parris (56) reported that
WftiHW debanram*ffi and P. anhanldermatufl started the Infection
Taubenhaus (75) in 1921 concluded that Diolodia tuberlcola
caused blossom-end rot of watermelons. However, Blodgett (8)
was unable to control the disease by use of fungicides.
Stuckey (73) postulated in 1924 that blossom-end rot
is probably a physiological disturbance brought on by rapid
changes in soil moisture as the young fruit start to grow.
He reported it is of little consequence in low-lying loamy
sands where the water table is near the surface. Walker (82)
in 1931 noted that blossom-end rot had been observed in con-
nection with pollination work and that defective pollination
appeared to be the most important factor in initiating it.
He pointed out that considerable decline of the melon occurred
before fungi appeared. Nettles and Halsey (53) were unable
to associate the incidence of blossom-end rot with fertilizer
rates of up to 2,000 pounds of 6-8-8 or with plant spacings
of 3, 6, 9, and 12 feet. Everett and Geraldson (22) obtained
a lower percentage of melons exhibiting blossom-end rot from
plots receiving one-half ton of hydrated lime or gypsum per
acre plus two tons of dolomite than from plots receiving
dolomite alone.
Geraldson (27) has shown similar blossom-end disorders
in tomatoes and peppers may be produced by insufficient cal-
cium in the substrate or by high concentrations of soluble
salts. Taylor and Smith (74) reported significant increases
10
in blossom-end rot of tomatoes as a result of high nitrogen
levels.
Brantley (11) associated the occurrence of blossom-
end rot of watermelons with high nitrogen levels; however,
no data were presented.
Calcium in Plant Nutrition,
Role in the soil
Soil scientists have vividly demonstrated that the
application of lime affects not only the chemical properties
of the soil but also the biological and physical properties
as well. The beneficial chemical effects of liming acid
soils result from: (l) increased availability of calcium
and possibly certain other nutrient elements and (2) pH
changes which influence the solubility of other elements,
both essential and non-essential.
In work reported by Marshall (46) a considerable part
of the absorbed calcium in kaolinitic type clays became active
at calcium saturation percentages of 39 to 59 while 70 to 80
per cent calcium saturation was necessary in montmorlllonitic
type clays. According to Sharpies and Foster (66) maximum
growth of cantaloupes on Arizona desert soil occurred between
50 to 60 per cent calcium saturation with growth decreasing
rapidly on either side of this range. Fried and Peeoh (25)
in several field and greenhouse experiments have demonstrated
that increasing the calcium supply with gypsum, in contrast
to limestone, failed to increase plant growth of such crops
11
as barley, alfalfa, and perennial ryegrass.
Many workers have shown that the solubility of alumi-
num, manganese, iron, boron, copper, and zinc increases with
increasing acidity (25, 38, 61, 65, 71, 86). Toxic concentra-
tions of such elements as aluminum, manganese, and iron may
develop below pH 5.5; moreover, such elements as manganese,
iron, and boron may become deficient above pH 6.5.
The soil biological population is Influenced by cal-
cium directly as an essential element for metabolism and
indirectly through alterations in the soil reaction (l, 4,
13, 83). Microbiologists have demonstrated that, in general,
fungi thrive when the pil is below 6 and bacteria and acti-
nomycetes prefer media above pH 6 (1, 13, 48, 81). This
points out the necessity for liming acid soils to obtain
maximum benefits from nitrifying bacteria as well as from
other biological processes involving principally bacteria.
Baver and Hall (5) and Meyers (49) have shown that
calcium ions do not affect the physical properties of organic
or inorganic colloids any more than do hydrogen ions. After
reviewing the literature on this subject Baver (4) concluded
the main effect of lime on the soil physical properties,
especially aggregation, resulted indirectly from its effect
on the production and decomposition of organic matter.
£fil£ in Plants
Calcium enters into several important physiological
processes within the plant. One of its most important roles
12
is the reaction with pectle acids to form calcium pectate,
a constituent of the middle lamella of the cell wall (9, 48,
50). Peotlc acid Is composed of long chains of galacturonic
acid residues which possess the 6-nembered pyranose ring
structure with a carboxyl group on the number five carbon.
This carboxyl group is free to combine with available cations
such as calcium, potassium, and magnesium thereby forming
pectates.
Calcium reacts with certain organic acids, especially
oxalic and malic, to form relatively Immobile oxalate com-
pounds (6, 9, 79). According to Meyer and Anderson (48)
these oxalate compounds occur in the cell vacuoles In large
quantities.
Plant physiologists point out that it was once be-
lieved that organic acids were toxic; therefore, calcium and
other cations were absorbed to precipitate these acids.
However, according to Meyer and Anderson (48) and Shear,
Crane, and Meyers (68) cell sap must be electrostatically
neutral; therefore, if greater absorption of cations than
anion occurs the plant cells produce certain organic acids
to precipitate the cations.
Nightingale (54) reported that In the absence of cal-
cium some species are unable to absorb nitrates.
It Is generally believe that calcium is necessary for
the continued growth of meristematlc tissue. This is appar-
ent by the symptoms of calcium deficient plants. The leaves
of plants grown In media low in Calcium, especially the
13
young leaves, often are distorted, dark green In color, and
the margins pointed downward or cupped under (48, 50) . In
severe cases a deficiency Is manifested by cessation of
terminal growth and the development of chlorosis and necrotic
areas even in the older growth.
Calcium plays another Important role In plant growth
by its antagnostic effects on the absorption of other ions
(21, 44, 48, 50, 56, 79). The antagonism apparently works
in at least two ways. First, less toxic ions may depress
the uptake or accumulation of more toxic ions. For example,
sodium, potassium, or magnesium may be toxic in single-salt
solutions; however, this toxic effect is eliminated by the
addition of calcium. Second, proteins may become saturated
with a single salt thereby changing their normal composition.
The addition of other salts tends to balance the protein
colloidal system.
CaUppg In Plant llama.
Pat ton accumulation
It has been demonstrated many times that the concen-
tration and type of nutrient elements occurring in plant tis-
sue is dependent upon a number of interrelated environmental
conditions as well as the plant species in question. Numerous
literature reviews point out that the ratio or balance of the
various ions In the substrate has a direct effect on the
chemical composition of the tissue (6, 13, 21, 63, 65, 74) •
In a refinement and extension of nutritional theories proposed
14
by earlier workers. Shear and co-workers (67, 68, 69) state
that plant growth is a function of two nutritional variables,
intensity and balance, which are reflected in the composition
of leaves when the plants are In the same stage of growth
and development* Intensity refers to the total equivalent
concentration of all functional nutrient elements in the
plant. They pointed out that there is a definite cation:
anion ratio within the plant; therefore, an accumulation of
one or more cations must be accompanied by an equivalent
decrease in one or more cations at any given anion level.
Likewise, an accumulation of one or more anions at a given
cation level must be accompanied by a decrease in one or
more anions. The simultaneous accumulation of both cations
and anions, either organic or Inorganic, in plant tissue has
been observed by many authors (3, 13, 26, 63, 68, 69, 79).
Cooper (16) concluded that the relative rate of ab-
sorption and accumulation of nutrients by plants is propor-
tional to the relative activity (energy properties) of the
nutrients as measured by such means as standard electrode or
ionization potential. This conclusion has been subjected to
extensive criticism. Geraldson (27) explained the occurrence
of blossom-end rot of tomatoes as a calcium deficiency when
the plants were grown in high concentrations of soluble salts
on the basis that as the soluble salt concentrations Increase,
the relative activities (effective concentration) of the
divalent salts decrease at a more rapid rate than monovalent
salts. Also, the calcium to soil soluble salts ratic (actual
15
concentration) varies inversely with concentration.
Shear, Crane, and Meyers (69) working with young
tung nut trees found that Increasing the magnesium or potas-
sium in the substrate generally resulted in increased con-
centrations in the tissue; however, the total accumulation
of potassium* magnesium* calcium was generally decreased.
Moreover, increasing calcium in the substrate not only in-
creased the calcium in the tissue but also increased the
total accumulation of the three cations. This was explained
on the basis that since a large percentage of the absorbed
calcium in many species is inactivated by oxalate precipita-
tion and no longer able to affect the entrance of other
cations, the increased calcium accumulation would result In
an increasod total cation accumulation. Pierre and Bower
(59) pointed out that potassium absorption Is usually de-
creased in the presence of high concentrations of other
cations such as calcium and magnesium. However, under rela-
tively high levels of potassium, increasing the concentration
of other cations, especially calcium, may increase potassium
absorption and accumulation in many crops. After a critical
literature review Peech and Bradfield (58) concluded that the
addition of lime to soils may have no effect, may Increase,
or decrease the availability of potassium to plants depending
upon the degree of initial soil saturation. They indicated
that calcium may have little effect on the absorption of the
available potassium, at least at the concentrations found in
most soils. Meanwhile, Geraldson (26) indicated that the
16
application of excessive amounts of ammonium, potassium,
magnesium, or sodium to sandy soils of Florida limited the
uptake of calcium by tomatoes.
Reports on the specific cation nutrition of cucurbits,
especially watermelons, are limited. Bradley and Fleming
(10) observed that the potassium content of watermelon leaves
was influenced primarily by the addition of potassium to the
soil. The difference in potassium content of the leaves be-
tween treatments grew smaller as the season progressed. The
application of 60 pounds of potassium in the row significantly
reduced the calcium content of the watermelon leaves early
in the season but had no effect toward the end of the season.
In one of two seasons potassium applications significantly
reduced the magnesium content of the leaves early in the
season but had no effect on samples collected toward the end
of the growing season.
Sharpies and Foster (66) grew cantaloupes In Arizona
desert sand cultures with calcium saturation percentages of
2.9, 11.9, 36.2, 63.7, 72.5, and 86.6. They found that ex-
tremely high and low saturation percentages tended to restrict
potassium uptake while leaf calcium varied directly and mag-
nesium Inversely with the calcium saturation percentages.
Stark and Haut (72) reported that the calcium content of
cantaloupe leaves increased in a geometric proportion to the
calcium concentration in the substrate, while potassium and
magnesium increased in arithmetic proportions to the concen-
tration of these respective elements in the substrate.
17
Concentrations of 4 to 5 mllliequlvalents per liter (200-
300 ppra) appeared to produce the best growth. When calcium
was supplied at 4, 8, or 16 milliequivalents (80, 160, 220
ppm), Reynolds and Stark (62) obtained maximum top, root,
and fruit yields of cucumbers at the lowest calcium level,
and growth decreased as the calcium level increased.
Effects oX nitrogen on the. cation content
It has been established that not only the concentra-
tion of nitrogen in the substrate but also the source
(nitrate or ammonium) will have a profound effect on the
cation content of the tissue (3, 13, 48, 63, 67, 84).
It has been shown repeatedly that increasing the
proportion of nitrate to ammonium nitrogen in the substrate
increases the production of organic acids, especially oxalic
(13). Since oxalic acid precipitates much of the absorbed
calcium, plants growing under high nitrate levels may uti-
lize more calcium (3, 13, 48, 63, 67, 68).
Shear and co-workers (67, 68, 69), Gerald son (26),
and Burrus (13) pointed out that the activity of the ammonium
ion is very similar to the activity of the potassium ion and
will greatly affect the uptake of other cations. Shear and
Crane (67), by supplying the nitrogen as ammonium in contrast
to nitrate, reduced the cation content of tung leaves by the
following percentages: potassium— 18 per cent, magnesium —
25 per cent, and calcium— 46 per cent.
Bradley and Fleming (10) indicated that the soil
18
application of ammonium nitrate had no consistent effect on
the potassium, calcium, and magnesium content of watermelon
leaves. Sharpies and Foster (66) reported that the applica-
tion of ammonium nitrate in sand cultures of cantaloupes
significantly increased the potassium, calcium, and magnesium
content of the leaves and decreased the phosphorus content
under varying calcium and magnesium ratios.
Distribution o£ cations in. plants
Numerous studies have been conducted on the distri-
bution of cations in plant tissue employing both chemical
analyses and radio-isotopes (3, 7, 31, 43, 63). The follow-
ing generalizations may be drawn: (1) a large part of the
calcium is located in the leaves with considerably smaller
amounts occurring in the roots, stem, seeds, and meriste-
matic areas, (2) potassium is distributed more uniformly
throughout the plant than calcium with relatively large
quantities occurring in regions of merlstematic division,
translocation, and storage, and (3) magnesium is present in
somewhat smaller amounts than calcium or potassium with
relatively large concentrations occurring in the leaves and
in the seeds of some plants.
Hardh (31) showed with radiographs that calcium ac-
cumulates in cucumbers in clearly separated pits occurring
more frequently in the leaves than in the stems. Wilklns
(83) reported that cucurbit vines, namely, pumpkins, pre-
serving citrons, two types of squash, cucumbers, and canta-
loupes, contained large amounts of calcium ranging from 5
19
to 8.5 per cent calcium oxide, while the fruits at no time
contained over 0.75 per cent calcium oxide. The vines con-
tained up to 5.9 per cent potassium oxide and the fruit up
to 5.4 per cent depending upon the species. The magnesium
content of the vines was much less variable, ranging from
0.46 per cent to 1.30 per cent magnesium oxide, and the
fruit consistently contained even less magnesium than cal-
cium. Wilklns (83) also found an increase in the percentage
of calcium in the cucurbit vines toward maturity, and the
calcium content of the fruit decreased slightly toward ma-
turity. The opposite trends were true for both potassium
and magnesium.
METHODS AND PROCEDURES
The watermelon industry in North Central Florida was
surveyed by making field observations and soil analyses in
30 melon fields during the 1958 growing season. This aided
in familiarization with the fertility problems involved in
watermelon production.
The literature indicated that certain physiological
disorders of watermelons resulted from adverse chemical or
physical conditions of the soil. Therefore, profile exami-
nations were made and soil samples were obtained from plots
devoted to watermelon fertility experiments as described by
Nettles and Halsey (53) in the spring of 1953. Chemical
analyses of the soil samples were made to observe any pos-
sible correlation between the chemical constituents and the
presence of blossom-end rot.
In the spring of 1958 samples of watermelon tissue
were obtained from mature field-grown plants to determine
the distribution of calcium, potassium, magnesium, and
sodium in the various plant parts and the variation of these
elements from plant to plant. The samples for analyses were
taken from six plants grown under similar environmental con-
ditions and were bearing mature fruits. Samples for analyses
from each plant included the following locations: basal
leaves, mid-leaves, vine tips, basal stem, mid-stem, and fruit,
20
21
Bach tissue sample was analyzed for calcium, potassium,
magnesium, and sodium on the Beckman model DU flame spectro-
photometer by using procedures outlined by Breland (12) •
In order to evaluate the effect of interfering anions in
the watermelon tissue on the calcium determinations, each
sample was analyzed for calcium, with and without these ions
present. The method of removing the interfering anions from
the samples is given under the heading "Chemical Analyses •"
Preliminary experiments with nutrient solutions and
quartz sand were conducted to determine the feasibility of
these techniques for greenhouse culture of watermelons.
In addition to the major study reported below,
simultaneous exploratory work was conducted in the greenhouse
and field to observe the effects of foliar applications of
calcium chloride on watermelons. Plants grown in field soil
in greenhouse benches were sprayed with 0.25, 0.10, 0.08,
0.06, and 0.04 molar concentrations of calcium chloride to
determine optimum levels for foliar applications. Severe
leaf burning occurred at the 0.25 level and slight burning
was evident at the 0.10 molar concentration. The 0.04 through
0.08 molar levels appeared satisfactory for treatment. A
greenhouse sand culture experiment with 8 replications was
established to observe the effects of bi-weekly applications
of 0.04 molar calcium chloride spray versus no spray on the
watermelon plants. Adequate amounts of a basic nutrient solu-
tion containing 16 ppm calcium was supplied to each pot. A
field experiment containing three levels of a calcium chloride
22
foliar spray arranged in a randomized block design was con-
ducted during the 1959 season* The spray levels were no
spray, 0.04, and 0.08 molar concentrations of calcium chloride
applied every five days.
The major study consisted of two parts—a greenhouse
phase and a field phase. The greenhouse phase was organized
to study the effects of various calcium levels in nutrient
solutions on growth responses; sex expression; fruit set and
quality; and the accumulation of calcium, potassium, and
magnesium in the various plant parts. The field phase was
designed to investigate the effects of three levels of nitro-
gen and three levels of calcium on growth, yield, quality,
and cation composition of the watermelon plant. The Charles-
ton Gray variety of watermelons was used in all experiments.
Greenhou.se phage
A randomized block experiment with four replications
was initiated on April 15, 1959, to study the influence of
eight progressive levels of calcium on watermelon responses.
This test was conducted using a solution culture procedure
in which the calcium levels were supplied by the addition of
calcium chloride to a basic nutrient solution. Young water-
melon seedlings were produced by germinating seeds on wet
filter paper. Two of these seedlings constituted an experi-
mental unit when suspended by a wooden support in a four-
gallon glazed crook. The solution levels in the crooks were
maintained at 13 liters by dally application of deionlzed
23
water with a complete change of solution each week. Ade-
quate aeration was supplied to each crock by means of a
centrally located pump.
The concentration of calcium in the different treat-
ments is given in Table 1. Since it was necessary to use
large volumes of solutions, the concentration is given in
both parts per million (ppm) and milliequivalents per liter
(m.e./L) .
TABLE 1
CALCIUM LEVELS IN GREENHOUSE SOLUTION CULTURES
Greenhouse Treatment Calcium Calcium
Number PP* m.e./L
1
0
2
4
3
8
4
16
5
32
6
64
7
128
8
256
0.0
0.2
0.4
0.8
1.6
3.2
6.4
12.8
The composition of the basic nutrient solution is
shown in Table 2. The iron solution was prepared by dis-
solving 100 grams of sodium-iron versenol (12 per cent iron)
per 2.5 liters of deionized water, and l/lO millileter of
this solution was used per liter of nutrient solution. The
other elements were prepared by the procedure outlined by
Hoagland and Arnon (37).
The pH of all newly prepared solutions, regardless
of calcium level, was approximately 5.2. At the end of the
24
seven-day period, the pH of the solutions ranged from 6.0 to
6.8 depending on the size of the vines; therefore, no pH
adjustments were necessary.
TABLE 2
THE COMPOSITION OF THE BASIC NUTRIENT SOLUTION
FOR GREENHOUSE EXPERIMENT
Element
Source
Concentration
(ppm)
Nitrogen
KN03
70
Phosphorus
KH2po4
KNO^oPO.
MgS04
32
Potassium
234
Magnesium
48
Boron
H3BO3
0.5
Manganese
MnCl2
0.5
Iron
NaFeEIiTA
0.5
Molybdium
H2M0O4
0.05
Zinc
ZnS04
0.05
Copper
CuS04
0.02
Fifteen days after transplanting one plant per pot
was harvested and dry weights were obtained as an early
growth measurement. All flowers were hand -pollinated in
the early morning and the number of both pistillate and
starainate flowers produced per experimental unit was re-
corded daily. All fruits developed blossom-end rot In this
experiment and were harvested individually and oven-dried as
soon as the rot was obvious. Continuous records on growth
responses were maintained throughout the experiments.
The experiment ended June 15 and the following ob-
tained from each experimental unit: leaf, tip, and root
samples and dry weight of frul , roots, and vines. The leaf
25
samples were composed of eight mature leaves per plant. The
tip samples were composed of eight actively growing lateral
tips two Inches in length. The root samples were composed
of the entire root system from each experimental unit. All
tissue samples vere washed twice in delonized water before
drying, with each washing lasting approximately 10 seconds.
FJL£ld Phase
UeBcrjpUftP pX soil type and soil test
The area used in this experiment was located on the
Horticulture Unit of the University of Florida near Gaines-
ville, Florida. The soil was classified as Kanapaha fine
sand (2). The surface layer is medium gray, loose, acid,
fine sand and underlain by yellowish white, loose, strongly
acid, fine sand. This is underlain by a phosphatic lime
material. Kanapaha fine sand is relatively low in organic
matter, moderately to imperfectly drained, level to slightly
undulating with poor physical structure, and often located
near ponds or lakes.
Two soil samples were taken from each plot on April
1. One sample was taken in the bed and consisted of 5 cores
taken at four locations across the bed. The other sample
was taken from the calcium-treated area on each side of the
bed and consisted of 20 cores. The samples were analyzed for
available Ca0, MgO, K20, P205, N03, and PH by the University
of Florida Soil Testing Laboratory.
26
Field methods
An experiment containing three levels of calcium and
three levels of nitrogen arranged factorially in a balanced-
lattice design was conducted in the spring of 1959 on Kanapaha
fine sand. The calcium levels tested were at the rate of
0, 500, and 1,000 pounds of hydrated lime (Ca(0H)2)per acre.
The nitrogen levels tested were at the rate of 60, 120, and
180 pounds per acre applied as ammonium nitrate. The indi-
vidual plot size was 15 by 80 feet with each calcium treat-
ment being broadcast in a 10-foot band throughout the length
of each plot on February 20. This left an untreated area of
2.5 feet on both sides of each plot. An untreated area of
10 feet was left between the ends of the plots to serve as
a buffer area.
A single bed approximately 8 inches high and 18
inches wide was prepared in the center of each plot. One
half of the total nitrogen and a uniform application of 80
pounds of P^Og and 80 pounds of KgO per acre was placed in
two bands in the row on March 12. The remaining half of the
nitrogen was plowed into both sides of the bed May 1, when
the vines began to develop.
Sixteen hills of watermelons were planted per plot
on March 26, and an excellent stand of plants was obtained.
Two weeks after emergence the melons were thinned to two
plants per hill. The methods used for cultivation. Insect,
and disease control were in accordance with recommended prac-
tices for the North Central Florida area. The melons were
27
harvested four times (June 17, 22, 26, and July 3) and the
following data obtained on all fruits from each plot: number
and weight of early marketable yield; number and weight of
total marketable yield; mean thickness of rind of each fruit
measured at the top center and bottom center; thickness of
rind at blossom-end; percentage soluble solids; percentage
blossom-end rot; and cutting quality including data on hollow-
heart, white-heart, and other abnormalities. The first three
harvests were considered to represent the early yield, and
all normally shaped melons over 16 pounds in weight were con-
sidered as U. S. number 1. Soluble solids were determined
on a Carl Zeiss water-cooled refractometer.
The amount of rainfall recorded in the immediate area
of the experiment is presented in Table 3.
TABLE 3
TOTAL BI-MONTHLY RAINFALL RECORDED AT THE HORTICULTURE
UNIT MARCH 1 TO JUNE 30, 1959
Date Inches of rain
March 1-14 3 22
March 15-31 o *£?
April 1-14 ?*£1
»:u \5;l° 2:0?
May 1-14 0 70
May 15-31 §*™
June 1-14 f'K
June 15-30 2 32
Total 25.51
28
Since there was an extremely large amount of rain-
fall following the first fertilizer application early in
March, an attempt was made to estimate the fertilizer loss
from the upper 8 inches of soil as a result of more than 8
Inches of rain. An extra row was fertilized on April 1 at
the rate of 90 pounds of nitrogen and 80 pounds each of
p2°5 and K2° per acre« This was located beside a row which
received the same fertilizer treatments before the rains.
Six soil samples were taken on April 1 from each of these
two rows, as well as from a third row receiving no fertilizer,
and analyzed for CaO, MgO, P205, *20' N03» and PH*
TlPPue sample?
On May 1, just prior to the second application of
nitrogen, every other hill of the young watermelon plants
from each plot was harvested and pooled into one composite
sample, and the oven-dry weight was obtained. Prior to dry-
ing, tip and leaf samples were taken from each composite
sample for chemical analyses. Additional leaf and tip sam-
ples were obtained from each plot for chemical analyses one
week prior to the first harvest of fruit. At this time the
plants were in a vigorous state of growth with little ap-
parent disease or insect damage. The leaf sample from each
plot was composed of the first two normal leaves, including
the petiole, from each plant. The tip samples consisted of
four actively growing vine tips from each plant located in
each plot. These tips were 2 Inches in length and included
29
very young leaves and a email end portion of the stem. The
leaf and tip samples were oven-dried and stored.
The fruits exhibiting blossom-end rot were removed
from the vines at the beginning of the harvest period and
a composite fruit sample was obtained from six representa-
tive fruits from each plot. Three cores, one inch in dia-
meter, were taken through the center of each fruit by use
of a soil sampling tube. These cores were then cut into
sections one-half inch long and mixed thoroughly; after
which, four 90-gram subsamples were weighed from each plot
sample. Two of these were frozen at 0° F. for subsequent
chemical analyses. The remaining two samples were used for
moisture determinations. Similar subsamples for analyses
were obtained from the first six normal fruits harvested
from each plot.
Chemical Analyses
All tissue samples were dried in a forced air oven
for 48 hours at 70°C. After which all leaf, tip, root, and
greenhouse fruit samples were ground in a Wiley Mill and
stored in one-pound paper bags. One-gram samples of the
oven dried tissue were ashed in a muffle furnace at 450°C,
dissolved in 15 milliliters (ml.) of 40 per cent hydrochloric
acid (HC1), evaporated to dryness, reheated in the muffle
furnace at 450°C. for 30 minutes to 3 hours (depending on the
amount of black carbon present), dissolved in 1 ml. of
30
concentrated HC1, evaporated to dryness, and diluted to
volume with 0.1 normal HC1.
Fruit samples collected from the field experiment
were dried in 250 ml. beakers and ashed in the same manner
as the other tissue samples. The entire sample was ashed
and calculations were based on the oven dry weight of the
sample less beaker weight.
All samples were analyzed for potassium, calcium,
and magnesium on a Beckman model DU flame spectrophotometer
following the procedure outlined by Breland (12) • Before
the calcium and magnesium determinations were made, 10 ml.
aliquots of each sample were passed through a six-inch column
of anion exchange resin (Dowex 1-8X, 50-100 mesh, medium
porosity) to remove interfering anions (39) .
Statistical Methods
The data were analyzed by the analysis of variance
methods described by Cochran and Cox (15) . Probability
statements of comparisons among means are based on the
Duncan Multiple Range Test (19) • Count data were trans-
formed by the square root method and percentage data by the
arcsin transformation before statistical analyses were made.
All growth response data presented from the field experiment
were derived from the adjusted treatment totals of the
balanced-lattice design.
RESULTS OF EXPERIMENTS
Examination of soil test data obtained from the field
survey indicated that, in general, low yields and a high per-
centage of blossom-end rot were associated with low nutrient
levels, especially calcium and magnesium.
Data obtained from fruit counts and soil studies from
fertility experiments described by Nettles and Halsey (53)
revealed that significant differences in the percentage of
blossom-end rot could not be attributed to fertility treat-
ments of differential levels of available soil nutrients.
In two of the three fertility experiments significant dif-
ferences in the percentage of blossom-end rot did result
from replications. Further examination of the data showed
that in one of the experiments the percentage of blossom-
end rot decreased significantly from the higher to the lower
elevation of the field. Examination of the soil profile re-
vealed that the soil in the upper portion of the field was
slightly compact for the first 18 inches then was very loose
to a depth of over 6 feet. The compactness of this upper
portion of the soil decreased from the higher to the lower
elevation of the field. From field examination of the pro-
file, at the lower elevation the soil appeared to have a
more desirable texture, more organic matter, and was darker
in color. Examination of the data from a second experiment
31
32
indicated that replications located on a soil with a loose
porous profile produced significantly more blossom-end rot
than replications located on a soil with a hard-pan 12 to
24 inches below the surface. In the third experiment no
significant differences resulted from replications. Examina-
tion of this soil profile revealed a uniform, relatively loose
profile with no observable textural or structural differences
throughout the experimental area.
The distribution of calcium, potassium, magnesium,
and sodium in the various parts of mature watermelon plants
grown under similar environmental conditions during the
spring of 1958 is shown in Table 4. By passing the sample
solutions through an anion exchange resin, calcium determi-
nation values were, in general, from 20 to 35 per cent greater
than those obtained from samples in which this step was elimi-
nated. The greatest concentration of calcium, irrespective
of analytical methods, and of magnesium occurred in the older
leaves with the percentages decreasing at the various sampling
locations in the following order: basal leaves, mid-leaves,
tips, stems, and fruits.
Statistical comparisons of the percentage of potassium,
calcium, and magnesium present at different locations in the
plants are shown in Table 5. The concentration of potassium
was significantly less in the leaves than in other plant parts
with the largest concentrations occurring in the stems and
fruits. There was no significant difference between the cal-
cium content of the stem sampling positions; however, the
33
as
55
o w ■<*» ^ oo ev»
'i* co n cm co co
o © © o o o
if
00 o
H ©
©
©
©
«
oo
00
to
CO
9
a)
o
CM
o
n
o
lO
©
5
n ih
tO
CM
CM
©
cm
n
c
o
«H
■*»
a
©
o
00
©
>
a
©
05
00
00
©
>
ft
f-t
I
a-
©
09
Ol
K
«
©
©
CM
oo
oo
CM CM CM eM
I 3
10 H i-4
CO © M
■
I
00
•♦»
2
u
9
u
3
0)
I
c
©
>
e
©
♦»
a
o
09
c
e
«H
■*>
a)
«
©
M
*4
0B
O
©
M
a)
fc.
©
>
•
M
al
■♦»
C
©
a
h
p.
xi •
o »
OjiH
CC »
al a)
«
■H
©
s
34
calcluci percentages of all other sampling locations within
the plant vere significantly different from each other. This
was true for the samples passed through the anion exchange
columns as well as for those not passed through the columns.
The magnesium content of the sampling positions in the stems
did not differ significantly; however, the magnesium content
of all other sampling locations within the plants differed
significantly.
TABLE 6
TEST OF SIGNIFICANCE FOR THE PERCENTAGE OF POTASSIUM,
CALCIUM, ANU MAGNESIUM AT SIX LOCATIONS
WITHIN MATURE WATERMELON PLANTSa
Potassium percentage
Mid-
Locations leaves
Basal Basal Mature
leaves Tips stem fruits
Mid-
stem
Calcium and magnesium
Mature
Locations fruit
Mid- Basal Mid-
stem stems Tips leaves
Basal
leaves
Any two locations underlined by the same line were
not significantly different. Any two locations not under-
lined by the same line were significantly different at the
5 per cent level (See Table 33 for A.O.V.).
^Significance table for calcium analyses both with
and without anion exchange resins.
35
There was far greater variation in the sodium con-
tent from one plant to another than from sampling locations
within any one plant; consequently, sodium analyses were
eliminated in later work.
Results from exploratory foliar spray experiments
were Inconclusive. Vine growth in the greenhouse was not
affected by foliar application of 0.04 molar calcium chlo-
ride. When each plant was allowed to set one fruit , all
eight of the vines receiving no spray produced fruits with
obvious blossom-end rot. Two of the eight plants receiving
bi-weekly sprays of 0.04 molar calcium chloride produced
fruit with obvious blossom-end rot. The remaining six plants
produced fruits with no external symptoms of rot; however,
examination of the internal tissues revealed that three of
the fruits had a semi-dehydrated, whitish, leathery type of
tissue at the blossom-end. There were no significant dif-
ferences in vine growth, yield, or percentage of blossom-
end rot obtained from the foliar spray treatments of the
field experiment. However, it should be pointed out that
the plants in this experiment were injured considerably by
excessive rains.
frreenhou.se Phase
Growth responses
All plants grown in solutions void of calcium became
stunted, chlorotlc and all but one plant died within two
36
weeks after transplanting. One plant per experimental unit
was harvested from the seven remaining treatments 18 days
after transplanting. The analysis of variance of the data
revealed no significant differences In the dry weights of
root 8 or tops.
Slight calcium deficiency symptoms became apparent
on newly developing leaves of plants grown in 4 ppm calcium
(treatment 2) on May 8. By May 15, these deficiency symptoms
were very pronounced In both the tops and the roots, and the
symptoms became increasingly more severe as the season prog-
ressed. The leaves of deficient plants were dark green in
color, moderately cupped under at the margins, and severely
restricted especially at the apex forming a more circular
type leaf (Fig. 1, No. 2).
The vine laterals of plants in treatment 2 were
shorter and much more numerous than those of the other treat-
ments. Frequently terminal growth of these short laterals
would cease and more short laterals would appear which would
in turn often produce other short laterals. This type of
growth pattern suggested a retardation or cessation of the
activity of the merstimatlc tissue at the apex of each vine
lateral. There were no observable differences in either vine
laterals or leaf formation of plants In treatments 3 through
8. However, the leaves of treatments 7 and 8 were lighter
green in color and appeared to be smaller In size (Fig. 1).
The root systems of plants grown in treatment 2
exhibited a growth pattern similar to the vine laterals with
Fig. 1. — The twelfth leaf from the
base of the plants in treatments 2, 3, 4,
7, and 8 of the greenhouse experiment.
Treatments 5 and 6 were eliminated to con-
serve space, because they did not appear to
be different from 4.
Br^ ^k ^k JM
^^L ^k^ ^L _^^3
lit '
^^^9
^^^^rr^ v j
^l
^■^^
39
the roots being short , dense, Tory numerous, and often dark
at the apex Indicating death (Fig. 2). Root systems of
treatment 3 showed these symptoms in a very limited degree.
The root systems of treatments 4 through 8 appeared to be
normal*
Since the calcium levels used in this experiment were
4, 8, 16, 32, 64, 128, and 256 ppm, that is, increased in
the ratio of 2 to 1, statistical analyses and interpretations
of the data were facilitated by considering all responses as
measured against the logarithms of the calcium concentrations.
Thus, in the analysis of variance of all data pertaining to
the greenhouse experiment and to the discussion of linear and
non-linear effects, the Independent variable is always the
logarithm of the amount of calcium added to the nutrient
solutions.
The dry weights of vines, roots, fruits, and the
total dry weight of plants are presented in Table 6. When
the vine growth was measured against the Increasing calcium
levels, it was found to decrease in a highly significant
linear trend, while the root growth responded in a signifi-
cant cubic fashion. There were no significant differences
in the dry weight of the entire plants (vines, roots, and
fruits), although it appeared to be curvilinear. Statistical
analysis was not made on the dry weight of the fruits, because
they were harvested whenever external blossom-end rot became
evident.
N^
Fig. 2 .—Representative root systems
from treatments 2, 3, 5, 7, and 8 of the green-
house experiment. Treatments 4 and 6 did not
appear to he different from 5.
42
TABLE 6
THE EFFECTS OF CALCIUM TREATMENTS ON THE DRY WEIGHT
OF VINES, ROOTS, FRUITS, AND TOTAL WEIGHT
IN THE GREENHOUSE EXPERIMENT
Treatment
Dry weight in grams
Number
Ca Levels
ppn
Vines
Roots
Fruits
Total
2
4
79.60
5.84
0.00
85.44
3
8
91.10
5.80
1.76
98.66
4
16
81.60
5.95
33.23
120.79
5
32
61.13
3.80
39.84
104.76
6
64
60.80
4.12
26.86
91.79
7
128
66.82
3.72
26.91
97.45
8
256
Effect :b
60.05
5.15
32.84
98.16
Linear
**
*
N. S.
Quadratic
N. S.
N. S.
___
N. S.
Cubic
N. S.
*
___
N. S.
* Significant at the 0.05 level
** Significant at the 0.01 level
N.S. Not significant
aEach figure is the average of four replications
measured in grams.
The linear, quadratic, and cubic effects were
determined by using log x as the Independent variable,
where x is the concentration of calcium in ppm in the
nutrient solution (see Table 34 for A.O.V.)
Sejt expression and fruit SSk
The number of pistillate and stamlnate flowers, the
ratio of stamlnate to pistillate flowers, and the number of
fruits set are given in Table 7, and the comparisons of the
square root of the means are given in Table 8.
43
TABLE 7
THE EFFECTS OF CALCIUM TREATMENTS ON FLOWER PRODUCTION
AND FRUIT SET IN THE GREENHOUSE EXPERIMENT
Treatment Ave. No. of flowers produced Total
numl
of J
set
Number Ca levels Staminate Pistillate Ratio number
ppm S:P of fruits
2
4
155.1
5.80
27.79
0
3
8
247.2
28.42
8.74
1
4
16
182.4
22.78
8.16
9
5
33
119.3
14.92
8.10
11
6
64
152.6
17.93
8.54
12
7
128
184.7
18.70
10.21
11
8
256
155.4
15.62
11.68
12
Treatment 3 produced significantly more and treatment
5 produced significantly fever staminate flowers than any
other treatments. Treatment 2 produced the least number of
pistillate flowers while treatment 3 produced the largest
number. The ratio of staminate to pistillate flowers was
significantly greater in treatment 2 than in any of the other
treatments. No fruit was set on plants in treatment 2 (4
ppm calcium) and only one fruit was set by plants in treat-
ment 3 (16 ppm calcium). There were no significant dif-
ferences in the number of fruit set from treatments 4
through 8.
Almost all the ovaries produced by plants grown in
treatment 2 turned dark brown to black in color beginning at
the blossom-end, even before the flower parts opened. This
also occurred rather frequently in the plants in treatment
3, but it was not observed in any of the other treatments.
44
TABLE 8
TEST OF SIGNIFICANCE FOR THE EFFECTS OF CALCIUM
TREATMENTS ON FLOWER PRODUCTION IN
THE GREENHOUSE EXPERIMENT
Staminate flowers
Treatment
Treatment
Mean (sq.
root)
5
8
Mean (sq. 10.92 12.35 12.45 12.46 13.50 13.59 15.75
root) «—__»__—_— «__«-__—_-______---—-_
Pistillate flowers
2 5 8 6 7 4 3
2.41 3.86 3.95 4.24 4.32 4.77 5.33
Ratio of staminate to pistillate flowers
Treatment
6
8
Mean (sq. 2.85 2.86 2.92 2.96 3.20 3.42 5.27
root)
Notes:
Any two means underlined by the same line are not
significantly different. Any two not underlined by the same
line are significantly different at the 5 per cent level
(see Table 35 for the A.O.V.).
45
Chemical composition
The effects of varying levels of calcium in the sub-
strate on the percentage of calcium, potassium, and magnesium
in the leaves, tips, roots and fruits are presented in Tables
9 and 10. Statistical analyses revealed that as the loga-
rithms of the calcium concentrations were Increased by equal
amounts in substrate the calcium content of the leaves in-
creased in quadratic fashion, the potassium content decreased
in a highly significant linear trend, and the magnesium con-
tent decreased in a highly significant quadratic manner.
The calcium content of the plant tips increased
linearly, the magnesium content decreased in a curvilinear
fashion, and the potassium content was not significantly
affected by Increasing Increments of calcium in the nutrient
solutions •
As the calcium levels were Increased, the percentage
of calcium in the root tissue increased in a highly signifi-
cant cubic manner, and both the potassium and magnesium
percentages decreased linearly.
Analyses of the fruit from treatments 4 through 8
indicated that the potassium content of the fruit was not af-
fected by varying the calcium concentration of the substrate.
However, there was a highly positive linear regression in
the calcium content and a highly negative linear response in
the magnesium content of the fruits when measured against
increasing calcium concentrations in the nutrient solutions.
46
TABLE 9
THE EFFECTS OF CALCIUM TREATMENTS ON THE PERCENTAGE
OF CALCIUM, POTASSIUM, AND MAGNESIUM IN THE
LEAVES AND TIPS OF PLANTS GROWN
IN THE GREENHOUSE4
Treatment
Leaves
Tips
Number 2a levels
Ca
K
Mg
Ca
K
Mg
(ppm)
2
4
0.32
5.19
2.07
0.088
4.16
0.557
3
8
0.48
4.79
1.45
.117
3.54
.490
4
16
1.04
4.14
1.89
.270
3.81
.603
5
32
3.12
4.02
2.06
.285
4.04
.575
6
64
3.90
3.54
1.41
.347
3.59
.460
7
128
4.95
3.72
0.89
.303
3.77
.345
8
256
Effect:1*
5.01
3.36
0.53
0.385
3.76
0.322
Linear
**
**
*♦
ft*
N.S.
♦*
Quadratic
N.S.
N.S.
**
N.S.
N.S.
*#
Cubic
**
N.S.
N.S.
N.S.
N.S.
N.S.
* Significant at 0.05 level
** Significant at 0.01 level
N.S. Not significant
aEach percentage is the average of four replications
on the dry weight basis.
^Linear, quadratic, and cubic effects were determined
by using log x as the independent variable, where z equals
the concentration of calcium in the nutrient solution in ppm
(see Table 36 for A.O.V.).
47
TABLE 10
THE EFFECTS OF CALCIUM TREATMENTS ON THE PERCENTAGE
OF CALCIUM, POTASSIUM, AND MAGNESIUM IN
THE ROOTS AND FRUITS OF PLANTS
GROWN IN THE GREENHOUSE*
Treatment Roots Fruits
•V umber
Ca levels
(ppm)
Ca
K
M ■
Ca
K
IU
2
4
0.19
5.33
0.525
w««
■»«•«
waw
3
8
0.25
4.92
.415
-_-
...
4
16
0.38
4.69
.420
0.095
4.87
0.370
5
32
0.41
3.80
.315
.105
4.40
.320
6
64
0.55
4.01
.312
.175
4.73
.295
7
128
1.39
3.79
.302
.265
4.72
.273
8
256
Effect :b
4.85
3.76
0.253
0.313
4.53
0.235
Linear
**
♦*
**
**
N.S.
**
Quadratic
**
N.S.
N.S.
N.S.
N.S.
N.S.
Cubic
**
N.S.
N.S.
N.S.
N.S.
N.S.
* Significant at 0.05 level.
** Significant at 0.01 level.
N.S. Not significant
aEach percentage is the average of four replications
on the dry weight basis.
^Linear, quadratic, and cubic effects were determined
by using log x as the independent variable, where x equals
the concentration of calcium in the nutrient solution in
ppm (see Tables 36 and 37 for A.O.V.).
48
E1&2& Phase
Soil tests
The results of the analyses of soil samples taken
within the beds are presented in Table 11. In general, the
results show good correlation with the amount of hydrated
lime applied. The variability within treatments may be
partially attributed to at least two factors: (1) at the
time of sampling small particles of hydrated lime were still
visible in some of the soil samples and (2) replication
number 3 was abnormally high in the various elements; this
tended to Increase the average values of all tests (see
Appendix Table 31).
TABLE 11
THE pH AND POUNDS PER ACRE OF AVAILABLE NUTRIENTS
OF SAMPLES TAKEN FROM THE WATERMELON
BEDS ON APRIL 1, 1959a
Treatments11 pH CaO MgO P205 K20 N03
Ca N 4.9 234 101 93 263 VL
CagNj
Ca0N2
CaiN2
Ca2N0
Ca2Nx
Ca2N2
aEaoh value is the average of four replications.
bCa0-none# Cal=500# and Ca2«l,000 lbs. of Ca(0H)2
per acre; No«60, NjslzO, and N2* 180 lbs. of N per aere.
"Memedlum, Lslov, VLsvery low.
5.0
147
85
90
227
L
4.8
145
98
86
247
L
5.3
373
73
77
226
L
5.4
653
90
89
267
L
5.4
629
87
90
226
L
5.8
1316
86
97
262
L
5.8
1511
65
99
231
M
5.8
1967
116
91
228
L
49
The data in Table 12 are from soil samples collected
from each side of the bed within the calcium treated area*
There was little difference in the pli and calcium content of
the various treatments. This may be explained by the fact
that the beds were prepared following the lime applications
which tended to concentrate the lime in the beds. The data
in Table 12, excluding calcium, represent the native fertility
of the plots (see Appendix Table 32).
TABLE 12
THE pH AND POUNDS PER ACRE OF AVAILABLE NUTRIENTS
OP SAMPLES TAKEN FROM EACH SIDE OF THE
MELON BEDS ON APRIL 1, 1959*
Treatments
pH
CaO
MgO
P2°5
V
HO.
CaoNo
Ca^'l
C*0N2
CaiN0
CalNl
CalN2
Ca2N0
CagNj
Ca2N2
4.9
188
94
50
69
VL
4.8
85
71
55
69
L
4.8
94
93
51
77
VL
5.0
94
58
49
58
L
5.0
188
90
48
53
L
4.9
102
75
51
52
L
5.0
154
62
52
49
L
5.1
146
57
51
37
L
5.0
186
80
48
58
VL
Each value is the average of four replications.
The effeots of heavy rains on the removal of ferti-
lizer from the upper eight inches of soil are shown in
Table 13. It is apparent from examination of the data that
all of the nitrates and approximately 50 per cent of the
KgO were leaohed from the upper eight Inches of the soil.
50
The excessive rainfall had very little effeet on the levels
of CaO, MgO, and P205«
TABLE 13
THE INFLUENCE OF MORE THAN EIGHT INCHES OF RAINFALL ON
THE REMOVAL OF FERTILIZER NUTRIENTS IN POUNDS
PER ACRE FROM THE UPPER EIGHT INCHES
OF SOIL IN WATERMELON BEDS*
Treatments
pH
CaO
MgO
P2°5
K20
N03C
Fertilizer
plus no rain
4.8
109
86
80
426
VH
Ferlitizer
plus 8" rain
5.0
80
65
90
228
L
No fertilizer
plus 8" rain
4.8
45
43
51
45
L
aEach figure is the average of six determinations.
bThe fertilizer rate was 90 lbs. N/acre as NH4N03i
i. K30/acre as KC1, and 80 lbs. of P20K/acre as trip]
tsphate.
°VH-very high, L-low.
Growth responses
The dry weight of plants from eight hills per plot
harvested May 1 is given in Table 14. There was a signifi-
cant linear increase in dry weight as the calcium levels
were increased. Nitrogen did not significantly affect early
vine growth or any other growth response measured in this
experiment •
The number of U. S. Number 1 watermelons harvested
early is given in Table 15. There was a highly significant
51
TABLE 14
THE EFFECTS OF CALCIUM AND NITROGEN ON EARLY VINE
GROWTH AS INDICATED BY THE DRY WEIGHT
OF EIGHT HILLS PER PLOT
Pounds of hydrated
line per acre
Pounds of nitrogen ner acre
60 120 180
Total
0
500
1,000
Total
196.30
214.05
208.20
618.55
204.00
206.35
212.35
622.70
193.75
237.25
251.50
682.50
594.05
657.65
672.05
Effect (from A.O.Y. in Table 38):
Calcium linear-significant at 0.05 level.
Nltrogen-not significant.
TABLE 15
THE EFFECTS OF CALCIUM AND NITROGEN ON THE NUMBER
OF EARLY U. S. NUMBER 1 WATERMELONS
Pounds of hydrated
lime per acre
Pounds
60
of nitrozen
120
per acre
180
Total
0
500
1,000
Total
25
30
37
92
23
32
28
83
18
31
44
93
66
93
109
Effect (from A.O.V. in Table 38):
Calcium linear-singlf leant at 0.01 level.
Nitrogen-not significant.
52
linear Increase In the number of early watermelons as a
result of the calcium treatments.
The total weight of U. S. Number 1 watermelons
which was harvested early are presented in Table 16. There
was a significant linear increase in the early yield, in
pounds, as a result of increasing increments of calcium.
TABLE 16
EFFECTS OF CALCIUM AND NITROGEN ON THE TOTAL WEIGHT
IN POUNDS OF U. S. NUMBER 1 WATERMELONS
HARVESTED EARLY
Pounds of hydra ted
lime per acre
Pounds
60
of nitroaren per acre
120 180
Total
0
500
1,000
Total
576.4
765.6
872.9
2214.9
568.3
725.8
626.1
1920.2
428.6
779.5
1148.5
2356.6
1573.3
2270.9
2647.5
Effect (from A.O.V. in Table 38):
Calcium linear-significant at the 0.05 level.
Nitrogen-not significant •
The total number of U. S. Number 1 watermelons har-
vested is given in Table 17. The total number of watermelons
produced increased in a significant fashion in response to
the calcium treatments.
The total weight in pounds of U. S. Number 1 water-
melons, reported in Table 18, increased in a significant
linear manner in response to the calcium treatments.
53
TABLE 17
EFFECTS OF CALCIUM AND NITROGEN ON THE TOTAL
NUMBER OF U. S. NUMBER 1 WATERMELONS
Pounds of hydra ted
lime per acre
Pounds of nitrogen per acre
60 120 180
0
500
1,000
Total
39
52
58
149
35
53
45
133
35
47
59
141
Total
109
152
162
Effect (from A.O.V. in Table 38):
Calcium linear-significant at the 0.05 level.
Nitrogen-not significant •
TABLE 18
EFFECTS OF CALCIUM AND NITROGEN ON THE TOTAL WEIGHT
IN POUNDS OF U. S. NUMBER 1 WATERMELONS
Pounds of hydrated
Pounds of nitrogen ner acre
Total
lime per acre
60
120
180
0
500
1,000
Total
851.8
1167.0
1267.8
3286.6
755.4
1140.4
938.3
2834.1
778.0
1118.6
1444.7
3341.3
2385.2
3426.0
3650.8
Effect (from A.O.V. in Table 38):
Calcium linear-significant at the 0.05 level.
Nitrogen-not significant.
54
The average of soluble solids as per cent sucrose
of all marketable fruit from each plot is reported in Table
19. The average percentage of soluble solids was not sig-
nificantly affected by either the nitrogen or the calcium
treatments.
TABLE 19
THE EFFECTS OF CALCIUM AND NITROGEN ON THE AVERAGE
SOLUBLE SOLIDS AS PER CENT SUCROSE FROM
ALL MARKETABLE MELONS PER PLOT
Pound 8 of hydrated
lime per acre
Pounds
60
of nitrogep per acre
120 180
Mean
0
500
1,000
Mean
9.97
9.78
9.48
9.74
9.65
9.94
9.46
9.68
10.24
10.12
9.72
10.03
9.95
9.95
9.55
Effect (from A.O.V. in Table 39):
Not significant.
The average thickness of the rinds measured at the
top and bottom center of all marketable fruits is shown in
Table 20. The average thickness of the rind at these loca-
tions was not affected significantly by any treatment com-
bination.
The average thickness of the rind at the blossom-
end of all marketable fruits per plot is given in Table 21.
A linear reduction in the thickness of the rind at the
blossom-end was associated with Increasing increments of
calcium.
55
TABLE 20
THE EFFECTS OF CALCIUM AND NITROGEN ON THE AVERAGE
THICKNESS OF THE RIND IN CENTIMETERS AT THE
TOP CENTER AND BOTTOM CENTER OF
ALL MARKETABLE FRUITS
Pounds of hydrated
lime per acre
Pounds
60
of nitrogen
120
per acre
180
Mean
0
500
1,000
Mean
2.006
1.797
1.722
1.842
1.712
1.818
1.709
1.746
1.883
1.722
1.957
1.854
1.867
1.779
1.796
Effect (from A.O.V. in Table 39):
Not significant.
TABLE 21
THE EFFECTS OF CALCIUM AND NITROGEN ON THE AVERAGE
THICKNESS OF THE RIND IN CENTIMETERS AT THE
BLOSSOM-END OF ALL MARKETABLE FRUITS
Pounds of hydrated
lime per acre
Pounds
60
of nitroiren
120
per acre
180
Mean
0
500
1,000
Mean
1.548
1.008
0.982
1.179
1.512
1.365
1.053
1.310
1.641
0.979
1.300
1.307
1.567
1.117
1.112
Effect (from A.O.V. in Table 39):
Calcium linear-significant at the 0.05 level.
Nitrogen-not significant.
56
The average percentage of blossom-end rot of the
watermelon fruits associated with each treatment combination
Is given In Table 22. The analysis of variance of this data
revealed no significant difference among treatments.
TABLE 22
THE EFFECTS OF CALCIUM AND NITROGEN ON THE
PERCENTAGE OF BLOSSOM-END ROT
Pounds of hydrated
lime per acre
Pounds
60
of nitrogen
120
per acre
180
Mean
0
500
1,000
Mean
46.52
48.83
44.64
46.66
47.27
46.46
49.56
47.76
39.93
51.55
42.10
44.53
44.57
48.95
45.43
Effect (from A.O.V. In Table 39)
Not significant.
All fruits were examined for hollow-heart, white-
heart, and other abnormalities; however, these disorders
were very limited in occurrence and of no importance in
this experiment.
Fruit gejfc.
The total number of fruits set per treatment is
shown in Table 23. There was a significant positive quad-
ratic response to the increasing calcium levels. Nitrogen
treatments had no significant effect on the total number of
fruits set.
57
TABLE 23
THE EFFECTS OF CALCIUM AND NITROGEN ON THE
TOTAL NUMBER OF FRUITS SET
Pounds of hydrated
line per acre
Pounds
60
of nitrogen
120
per acre
180
Total
0
500
1,000
Total
136.6
148.2
136.8
421.6
124.6
160.9
163.2
448.8
92.2
186.4
163.5
442.1
353.4
495.5
463.5
Effect (from A.O.V. in Table 39):
Calcium linear-significant at 0.05 level.
Calcium quadratic-significant at 0.05 level.
Nitrogen-not significant.
Chemical composition
The percentage of calcium, potassium, and magnesium
in the tips of young watermelon plants on May 1 is presented
in Table 24. There was a highly significant linear increase
in the calcium content of the tips as the calcium supply
was increased in the soil. The calcium content of the tips
was not affected by the nitrogen treatments. Neither the
potassium nor magnesium content of the young tips was in-
fluenced by the application of nitrogen or calcium to the
soil.
The cation composition of the leaves from young
watermelon plants is shown in Table 25. The calcium con-
tent of the leaves gave a curvilinear response to calcium
treatments, increasing with increasing amounts of lime per
acre. In response to nitrogen treatments, however, the
58
TABLE 24
THE EFFECTS OF CALCIUM AND NITROGEN ON THE PERCENTAGE
OF CALCIUM, POTASSIUM, AND MAGNESIUM IN THE
TIPS OF YOUNG WATERMELON PLANTS
Pounds of hydra ted
Pounds of nitrogen
per acre
Mean
lime per acre
60 120
180
Calcium Content
0
500
1,000
0.545 0.385
0.555 0.630
0.713 0.937
0.340
0.713
0.722
0.423
0.633
0.791
Mean
0.604 0.651
0.594
PoUffsium c<Mrtent
0
500
1,000
5.61 4.69
5.19 5.02
5.26 5.00
5.11
5.55
5.51
5.14
5.25
5.26
Mean
5.35
4.90
5.39
0
500
1,000
Mean
Magnesium Content
0.340
0.285
0.292
0.306
0.285
0.323
0.308
0.305
0.300
0.298
0.288
0.295
0.308
0.302
0.296
Effect (from A.O.V. in Table 40):
Calcium content-calcium linear (CaL) sig-
nificant at 0.01 level.
Potassium content-not significant.
Magnesium content-not significant.
59
TABLE 25
THE EFFECTS OF CALCIUM AND NITROGEN ON THE PERCENTAGE
OF CALCIUM, POTASSIUM, AND MAGNESIUM IN THE
LEAVES OF YOUNG WATERMELON PLANTS
Pounds of hydra ted
Pounds 0f nit. r oi?en
p«r acre
Mean
lime per acre
60 120
180
Calcium Content
0
2.73 2.41
1.96
2.37
500
4.15 3.81
3.59
3.85
1,000
4.21 4.31
4.06
4.19
Mean
3.70
3.51
3.20
Potassium Content
0
500
1,000
5.75
5.23
5.24
5.80
5.42
5.21
5.90
5.35
5.67
5.82
5.33
5.37
Mean
5.41
5.48
5.64
Magnesium Content
0
500
1,000
0.623
0.450
0.410
0.600
0.485
0.385
0.457
0.428
0.472
0.560
0.454
0.422
Mean
0.494 0.490
0.452
Effect (from A.O.V. in Tafcle 40):
Calcium- content-CaL, calcium quadratic
(Ca0), and nitrogen linear (NT ) significant
at 0.01 level. u
Potassium content-CaL significant at 0.05
level •
Magnesium content-Car significant at 0.01
level; C^ X NL significant at 0.05 level.
60
calcium content shoved a highly significant linear regres-
sion, decreasing as the nitrogen levels were increased.
Potassium content also shoved a significant linear regres-
sion, decreasing as the calcium levels vere increased in
the soil. The magnesium content of the leaves similarly
decreased in a highly significant linear trend as a result
of increasing the calcium levels. However, a significant
linear interaction was discovered between the linear re-
sponses of calcium and nitrogen, Ca^ X N , on the magnesium
content of the leaves of young plants (Fig. 3). The effect
of increasing nitrogen on the linear response to the calcium
treatments vas to change the regression from negative to
slightly positive as the nitrogen levels increased from 60
to 180 pounds per acre*
The effect of the calcium and nitrogen treatments
on the cation composition of the tips from the mature water-
melon plants is presented in Table 26. The calcium treat-
ments had no significant effect on the cation composition
of the mature tips. The potassium and magnesium content
of the tips, hovever, responded in a significant negative
linear fashion to the increasing nitrogen levels.
The cation composition of the leaves from mature
plants is given in Table 27. Nitrogen treatments had no
significant effect on the percentage of potassium, calcium,
or magnesium in the mature leaves. The calcium content of
the leaves vas increased in a highly significant quadratic
61
0.7U
0.6
CO
B 0.5
0.4
0.3
0.2
180
Jl
_L
-L
0 500 1,000
POUNDS OF HYDRATED LIME PER ACRE
Fig. 3. — The Interaction of calcium and
nitrogen (Car X NL) on the magnesium content of
the leaves or young watermelon plants
c
2.1
2.0-
co
2 1.9
H
O
H 1*8
as
W
O
- 1.7
1.6-
1.5
\^60 lbs. N
lbs. N
lbs. N
0 500 1,000
POUNDS OF HYDRATED LIME PER ACRE
Fig. 4. — The interaction of calcium and
nitrogen (CaQ X Nq) on the potassium content of
U. S. Number 1 watermelons.
62
TABLE 26
THE EFFECTS OF CALCIUM AND NITROGEN ON THE PERCENTAGE
OF CALCIUM, POTASSIUM, AND MAGNESIUM IN THE
TIPS OF MATURE WATERMELON PLANTS
Pounds of hydra ted
Pounds of nitrogen
ner acre
Mean
line per acre
60 120
180
Calciwp content
0
500
1,000
0.285 0.230
0.370 0.300
0.365 0.325
0.325
0.325
0.300
0.280
0.332
0.330
Mean
0.340 0.285
0.317
Potassium Content
0
500
1,000
3.85 3.84
4.06 3.35
3.84 3.26
3.75
3.35
3.56
3.81
3.59
3.55
Mean
3.92
3.48
3.55
Majrnesium Content
0
500
1,000
0.460
0.385
0.400
0.367
0.355
0.345
0.380
0.333
0.390
0.402
0.358
0.378
Mean
0.415
0.356
0.368
Effect (from A.O.V. In Tpole 41):
Calcium content-not significant.
Potassium content -NT significant at 0.05
level.
Magnesium content-Nr significant at 0.05
level.
63
TABLE 27
THE EFFECTS OF CALCIUM AND NITROGEN ON THE PERCENTAGE
OF CALCIUM, POTASSIUM, AND MAGNESIUM IN THE
LEAVES OF MATURE WATERMELON PLANTS
Pounds of hydrated
line per acre
Pounds of nitrogen
60 120
per acre
180
Mean
0
500
1,000
Calcium Content
4.21 4.50
8.16 8.88
9.90 8.23
4.63
8.72
9.15
4.45
8.59
9.09
Mean
7.42
7.20
7.50
Potassium Content
0
500
1,000
3.21
1.96
1.96
2.79
2.19
1.79
2.81
1.83
2.08
2.94
1.99
1.94
Mean
2.38
2.26
2.24
MagnesjmB Content
0
500
1,000
1.070
1.020
0.942
1.111
1.050
0.850
0.947
0.902
0.968
1.040
0.991
0.920
Mean
1.010
1.003
0.939
Effect (from A.O.V. in Table 41):
Calcium content-CaT , CaQ significant at
0.01 level. ** u
Potassium content-Cai,, Ca0 significant at
0.01 level. H
Magnesium content-not significant.
64
fashion and the potassium content was decreased in a highly
significant quadratic manner as the calcium levels were
Increased in the soil.
The results of the analyses of the mature marketable
fruit for calcium, potassium, and magnesium are shown in
Table 28* The calcium content increased in a highly sig-
nificant manner as a result of the calcium applications, and
it decreased in a highly significant quadratic fashion as a
result of the nitrogen treatments. The potassium content
showed significant quadratic regressions as a result of
both calcium and nitrogen treatments. However, these rela-
tionships are complicated by a quadratic interaction
(Caq X N ) shown in Fig. 4. The quadratic regression on
calcium changed drastically from "concave upward" for 60
and 180 pounds of nitrogen to "concave downward" for the
120 pounds of nitrogen applied per acre. The magnesium
content responded to nitrogen only, and this was a quadratic
relationship •
The composition of the fruits exhibiting blossom-
end rot is shown in Table 29. The calcium content of the
fruit showed a strong linear regression, increasing in re-
sponse to increasing increments of applied calcium. The
potassium content responded negatively to the calcium treat-
ments and positively to the nitrogen treatments. However,
a significant interaction (CaL X Nq) is quite evident in
Fig. 5. Here the shape of the linear regression of
65
TABLE 28
THE EFFECTS OF CALCIUM AND NITROGEN ON THE PERCENTAGE
OF CALCIUM, POTASSIUM, AND MAGNESIUM IN
U.S. NUMBER 1 WATERMELON FRUITS
Pounds of hydrated
„ Pounds
of nitrocen
per acre
Mean
lime per
acre
60
120
180
CaJciwn content
0
500
1,000
0.106
0.163
0.185
0.095
0.135
0.135
0.101
0.131
0.162
0.101
0.143
0.161
Mean
0.151
0.122
0.131
Potassium Content
0
500
1,000
2.06
1.71
1.85
1.91
1.76
1.58
1.93
1.71
1.84
1.97
1.73
1.76
Mean
1.87
1.75
1.83
Magnesium Content
0
500
1,000
0.143
0.127
0.125
0.134
0.120
0.108
0.146
0.134
0.143
0.141
0.127
0.125
Mean
0.132
0.121
0.141
Effect (from A.O.V. in Table 42):
Calcium content-CaL significant at 0.01
level; N., NQ significant at 0.05 level.
Potassium content- CaL, CaQ singificant at
N
Q'
Jaq-X Nq significant at
0.01 level;
0.05 level.
Magnesium content-Nn significant at 0.05
level.
66
TABLE 29
THE EFFECTS OF CALCIUM AND NITROGEN ON THE PERCENTAGE
OF CALCIUM, POTASSIUM, AND MAGNESIUM IN
WATERMELON FRUITS EXHIBITING
BLOSSOM-END ROT
Pounds of
hydra ted
Pounds
of nitrocen
per acre
Mean
lime per
acre
60
120
180
Calcium Content
0
500
1,000
0.199
0.243
0.321
0.180
0.255
0.233
0.226
0.219
0.291
0.202
0.239
0.282
Mean
0.254
0.223
0.245
Potassium Content
0
500
1,000
2.15
2.36
2.34
2.92
2.54
1.98
3.01
2.49
2.48
2.69
2.46
2.27
Mean
2.28
2.48
2.66
Magnesium Content
0.238
0.181
0.156
0
500
1,000
0.180
0.184
0.159
0.218
0.154
0.124
0.212
0.173
0.146
Mean
0.174
0.165
0.192
Effect (from A.O.V. in Table 42):
Calcium content-Car. significant at 0.01 level.
Potassium content -CaT significant at 0.01
N
L*
'K
CaL X N^ significant at 0.05
level;
level.
Magnesium eontent-CaL significant at 0.01
level; CaL X NL significant at 0.05 level.
67
3.01-
s 2.8
M
CO
3 2.6
H
O
h 2.4
5":
K
O
« 2.2
2.0
1.8
/180 lbs. N
^60 lbs. N
120 lbs. N
1
0 500 1,000
POUNDS OF HYDRATED LIME PER ACRE
Fig. 5. — The interaction of calcium and
nitrogen (CaL X Nq) on the potassium content of
watermelon fruits exhibiting blossom-end rot.
0.24i-
0.22-
S 0.20
0.18
o
I
Pi
—
-
\^180 lbs.
N
-
^\^r60 lbs. N
-
i
i
^120 lbs. NT
0.16-
0.14-
0.12
0 500 1,000
POUNDS OF HYDRATED LIME PER ACRE
Fig. 6. — The interaction of calcium and
nitrogen (CaL x Ntl) on tne magnesium content of
watermelon fruits exhibiting blossom-end rot.
68
potassium on calcium changed markedly from positive to
negative in a curvilinear fashion for different levels of
nitrogen. The highly significant linear reduction in the
magnesium content in response to calcium treatments appeared
to be influenced by the nitrogen levels. It is evident by
the linear interaction (Ca~ X N^) of the magnesium content
on calcium shown in Fig. 6. The graph clearly shows how the
negative slope of the regression becomes steeper as the
nitrogen is increased above 60 pounds of nitrogen per acre.
DISCUSSION
Growth Responses
In the greenhouse experiments with watermelons, any
level of calcium In the nutrient solution from 4 to 256 ppm
appeared to produce normal growth of plants the first two
weeks after transplanting. After this, plants grown In
solutions containing 4 ppm of calcium began to develop
deficiency symptoms In the leaves, vines, and roots, and
these symptoms grew increasingly more pronounced as the
season progressed. Within three days all watermelon plants
placed In solutions containing no calcium began developing
deficiency symptoms which resulted in death of the plants in
approximately two weeks. These visible symptoms appeared to
be characteristic of a severe calcium deficiency rather than
toxicity jf any other element or elements. No deficiency
symptoms were apparent in the tops of plants grown in 8 ppm
calcium; however, the roots did show obvious deficiency
symptoms at the 8 ppm level but not at 16 ppm of calcium.
Research reported by Bidiulph et al. (7) indicated that Red
Kidney bean plants survived In nutrient solutions containing
as low as 0.05 mlllimoles (2 ppm) of calcium. Below this
level, the beans developed a severe deficiency or chlorosis
which resulted in death.
69
70
The negative linear relationships existing between
the dry weight of vines or the dry weight of the roots and
the calcium concentrations, when expressed logarithmically,
may be explained by the fruit yields (Fig. 7). In solutions
containing 16 through 256 ppm of calcium a considerable
part of the total plant weight was represented by the dry
weight of the fruits. This is apparent by observation of
the non-significant quadratic trend in total weight. The
curvilinear response of root growth is unquestionably mainly
a response to treatments; however, it may be partially
attributed to the amount of the base portion of the main
stem harvested with the root systems. Therefore, the nega-
tive linear pattern appears to describe the data adequately
(Fig. 7).
The positive linear response of early vine growth
to calcium treatments in the field (Table 14) is in general
agreement with data obtained from a preliminary sand-pot
experiment. Pots of Leon fine sand receiving 600 pounds of
hydrated lime per acre produced significantly more vine
growth than pots receiving no lime, but vine growth was not
significantly different in pots receiving 600; 1,200; 1,800;
or 2,400 pounds of hydrated lime per acre. Field application
of nitrogen did not Influence the early vine growth signifi-
cantly. This may be explained on either of the following
assumptions: (1) the excessive rains following application
partially eliminated the nitrogen variable or (2) sufficient
71
M IH
DRY WEIGHT IN GRAMS FOR THE ROOTS
t- «0 ifl ^
©
P-l »
GC
® C
* V
E
DRY WEIGHT IN GRAMS FOR VINES, FRUITS
AND TOTAL
72
nitrogen remained at all nitrogen levels after the exces-
sive rains to give maximum growth in the early stages.
The percentage increase in early and total yields
both in pounds and numbers are shown in Fig. 8. On an
acre basis the application of 500 and 1,000 pounds of
hydrated lime increased the number of early harvested water-
melons by 80 and 129 respectively. These figures represent
a percentage increase over the no lime treatment of 40 and
60 per cent respectively. On an acre basis the application
of 500 and 1,000 pounds of hydrated lime increased the
pounds of watermelons harvested early by 2,002.8 and
3,222.6 or 44 and 68 per cent respectively over the no lime
treatment. The percentage increase in the number of pounds
was slightly larger than the percentage Increase in the ac-
tual number of watermelons. This indicates that the average
weight per melon was slightly greater as a result of the
lime treatments; however, statistical analysis based on the
average weight per plot showed no significant difference.
When the total yield of U.S. Number 1 watermelons
per acre is considered, the application of 500 and 1,000
pounds of hydrated lime increased the yields by 127 and 156
watermelons (39 and 48 per cent) respectively. A compari-
son of the percentage increase in the total number with the
percentage increase in total pounds again indicates that the
melons were larger in size, and this is supported by statis-
tical significance based on the average weight per plot. It
should be pointed out, however, that the average weight per
73
E-
O
CO
c
E
CO
-a
c
S2 Pu
o
o
o
o
o
o
<
_r o
o
o
o
rt l~ o
■U C
O b/'
+> c b:
•H C
T3 > t-4
C i-t >
rf 0) t4
O C)
X ©
M
d co
© -tj co
o v
CHO
•^ P,rH
P.
a> S
CO o
d u
CD <m
£-,
© CO
c c
©
©
5-
©
>
©
©
E
o
o
o
o
o
o
9
o
o
o
OJ
00
t>
co
Ifi
n
C\J
© © ih
w E
d C TJ
■p © ©
C -P V
cd d d
© 3 t,
- ts
CD rH >5
P. X!
h
CD CD Cm
43 P ©
i 3 co
i as -a
c
or • 3
A O
• • £},
bot3
«H O
St. ft* O
O O
X} rH •
iH ©
© x) E
■H C "H
>> d r-i
PER CENT INCREASE
74
plot was based on unequal numbers; therefore, the analysis
of variance may be biased.
Since these yield increases were obtained from row3
spaced 15 feet apart and the hills 10 feet apart in the row,
even greater total yields were probable by spacing the rows
or the hills closer together. In commercial watermelon
fields rows are usually spaced 8 to 10 feet apart. Nettles
and Halsey (53) reported significant increases in the number
of watermelons produced as the number of hills per row were
increased. Plants spaced 3 feet apart in rows 10 feet apart
produced 1,260 marketable watermelons per acre, and plants
spaced 12 feet apart in 10-foot rows produced 660 marketable
watermelons per acre. The average weight did not differ
significantly, but it tended to be greater at the wider
spacings.
From the literature review and from examination of
all soil and tissue analytical data it appears that the
beneficial effects of calcium resulted from both an in-
creased supply of calcium and pH changes, which may have
directly or indirectly affected the availability of certain
other elements. In general, investigators agree that the
calcium to magnesium ratio in the soil should be in the
range 6 to 10:1. Data in Table 11 and 31 indicate the cal-
cium to magnesium ratios associated with the three treatments
(0, 500, and 1,000 pounds of hydrated lime per acre) were
approximately 1:1, 6:1, and 15:1, respectively. Likewise,
more favorable calcium to potassium ratios existed in the
75
plots receiving lime. The importance of these ratios is
exemplified by the data on the cation composition of the
plants shown in Tables 24 through 30. In general, the cal-
cium content of the plant Increased from 50 to 100 per cent
in response to added calcium, and the potassium and mag-
nesium content generally decreased. Moreover, WilfcLns (83)
pointed out that cucurbits accumulate large quantities of
calcium, and suggested that it may be desirable to plant
these crops on soils containing an abundant supply of cal-
cium.
Another undoubtably important factor contributing
to the increased yields is the soil pH. From data in
Table 11, it may be seen that the average pH corresponding
to the three calcium levels were 4.9, 5.4, and 5.8.
Fiskell and co-workers (23, 24) have shown that toxic con-
centrations of aluminum ions are present in many of the
Florida soils, including Kanapaha, with a low pH. Further-
more, it has been established that the rate of nitrification
as well as organic matter decomposition is greatly in-
fluenced by the soil pH (13, 81).
Nitrogen had no significant effect on any of the
yield data from the field experiment. This may be attributed
in part to excessive rainfall following both nitrogen ap-
plications. Over eight inches of rain fell the first 15
days following the initial application of nitrogen. Over
seven inches of rain fell the first 30 days following the
second application of nitrogen. Data in Table 13 indicated
76
that almost all of the nitrates and approximately 50 per
cent of the potassium was leached from the upper eight
inches of the soil by slightly more than eight inches of
rainfall. Since ammonium occupies a lower position in the
lyotrophic series than potassium it follows that at least
50 per cent of the ammonium nitrogen also was lost.
No definite relationship was established between
blossom-end rot and calcium treatments in the greenhouse
or the field. In all greenhouse work using nutrient cul-
tures, all the fruits set developed blossom-end rot.
Geraldson (26) observed that black-heart of celery, a cal-
cium deficiency, occurred in nutrient solutions in the green-
house regardless of the calcium levels. Black-heart was
controlled by foliar applications of 0.04 molar calcium
chloride. A similar control has been developed for blos-
som-end rot of tomatoes (27).
In the exploratory work in the greenhouse with water-
melons, a lower incidence of blossom-end rot was observed
with treatments receiving foliar sprays of 0.04 molar calcium
chloride than from pots receiving no spray. This does not
necessarily establish the disorder as a calcium deficiency;
however, it does support the theory that blossom-end rot is
a physiological disorder. This is further substantiated by
the fact that a large percentage of the ovaries of plants
grown in four and eight ppm calcium decayed beginning at
the blossom-end even before the floral parts opened. It is
suggested, therefore, that future examinations into the
77
causes of blossom-end rot of watermelons may be more prof-
itable If attempted under controlled environmental condi-
tions.
The differential calcium treatments tested In the
field did have an effect on the rlnd thickness at the
blossom-end of the watermelon but not on the average thick-
ness of the top and bottom center of the rlnd. At the
blossom-end the rlnd thickness decreased as the calcium
levels were Increased. At least two possible explanations
exist for this: it is possible that calcium enhanced ma-
turity; however, this is not supported by a significant
increase in the soluble solids, and observations have shown
that fruits affected with blossom-end disorders tend to have
a thick whitish rlnd at the blossom-end; therefore, increas-
ing the calcium supply may have reduced these disorders. It
should also be pointed out that the calcium content of the
fruit generally increased linearly in response to calcium
treatments.
SejL Expression, and frvX% *SLL
Calcium treatments had a profound effect on sex ex-
pression in nutrient solutions containing relatively low
amounts of calcium (Table 7). Plants grown in 13 liters of
a solution containing 4 ppm calcium had an average ratio of
staminate to pistillate flowers of 27.79:1. When the calcium
level was raised to 8 ppm the ratio dropped to 8.74:1 and did
not differ significantly as the calcium level was Increased
78
from 4 to 256 ppm; however, at the higher calcium levels
the ratio tended to increase. From data presented in Tables
9 and 10 it may be assumed that this drastic increase in
the flower ratio was due to either a deficiency of calcium,
an excess of potassium and magnesium in the nutrient solu-
tion, or any combination of the latter with a calcium de-
ficiency.
Apparently calcium concentrations greater than 8
ppm are necessary for fruit set. Since a large number of
the ovaries of plants in solutions containing 4 and 8 ppm
calcium decayed, it is assumed that insufficient quantities
of calcium were present for normal cellular development.
The parabolic response in the number of fruits set to cal-
cium treatments in the field may be explained on the basis
that the liming applications enhanced vine growth thereby
increasing the actual numbers of fruits set (Table 23).
Chemical Analyses
In the greenhouse experiment, the increase in the
calcium content of the tips and fruits was linear as the
logarithms of the calcium treatments increased, however, a
positive curvilinear response occurred in the leaves and
roots. It is generally agreed that increasing the concen-
tration of any element in the substrate usually results in
increased absorption of that element by the plant (44, 59) .
The linear decrease in the potassium content of the leaves
and roots probably was produced by a cation antagonism
79
resulting from an increase in the calcium content. The
failure of potassium to decrease significantly in the tips
and fruits may be explained on the basis that potassium is
a very mobile element and occurs in relatively large quan-
tities in areas of high metabolic activity (48, 50). Ap-
parently cation antagonism between calcium and magnesium
resulted in a linear decrease in the magnesium content of
the leaves and roots and a quadratic decrease in the tips
and fruits.
Conversion of the data in Table 10 to equivalents
per 100 grams indicated that the calcium-equivalent in-
crease in the plants at the various treatments was con-
siderably greater than the accumulative equivalent decrease
of potassium and magnesium. This may be attributed to
inactivation of much of the absorbed calcium by organic
acid precipitation thereby causing a continuous build-up
of the total cation equivalents in the tissue as calcium
increased in the substrate.
The influence of calcium and nitrogen on the aver-
age percentage of calcium, potassium, and magnesium of
tissue samples from the field experiment is shown in Table
30. The linear increase in the calcium content in response
to calcium applications occurred in the leaves of both
young and mature plants. The significant decrease in the
calcium content of the leaves at the first sampling date
as a result of nitrogen treatments failed to occur at the
second sampling date. This may be the consequence of
80
TABLE 30
THE AVERAGE PERCENTAGE OF CALCIUM, POTASSIUM, AND MAGNESIUM
ASSOCIATED WITH EACH CALCIUM AND EACH NITROGEN
LEVEL IN BOTH VINES AND FRUITS FROM
THE FIELD EXPERIMENT
Treatment
levels
Composition of young
plants
(May 1, 1959)
Composition of mature
plants
(June 10, 1959)
Leaves
Leaves
Cal clitm
Ca
K
Mg
Ca
K
Mg
0
2.37
5.82
0.560
4.45
2.94
1.04
500
3.85
5.33
.454
8.59
1.99
0.99
1,000
4.19
5.37
.422
9.09
1.94
0.92
Nitrogen
60
3.70
5.41
.494
7.42
2.38
1.01
120
3.51
5.48
.490
7.20
2.26
1.00
180
3.20
5.64
.452
7.50
2.24
0.94
Tips
Tips
Calcium
Ca
K
Mg
Ca
K
Mg
0
0.423
5.14
0.308
0.280
2.81
0.402
500
• 633
5.25
.302
• 332
3.59
.358
1,000
.791
5.26
.296
.330
3.55
.378
Nitrogen
60
.604
5.35
.306
.340
3.92
.415
120
.651
4.90
.305
•285
3.48
.356
180
0.594
5.39
0.295
0.317
3.55
0.368
Composition of U. S.
number 1 fruits
Composition of fruits
exhibiting
blossom-end rot
Cal dura
Ca
E
Mg
Ca
E
Mg
0
0.101
1.97
0.141
0.202
2.69
0.212
500
.143
1.73
.127
.239
2.46
.173
1,000
.161
1.76
.125
.282
2.27
• 146
Nitrogen
60
.151
1.87
.132
.254
2.28
.174
120
.122
1.75
• 121
.223
2.48
.165
180
0.131
1.83
0.141
0.245
2.66
0.192
Oven dry weight basis.
81
retardation In growth and less antagonism between ammonium
and calcium through leaching and oxidation of the ammonium.
The concentration of calcium in the leaves, regardless of
treatments, approximately doubled from the first to the
second sampling date. This is probably due to the precipi-
tation of a large percentage of the calcium by certain
organic acids.
The potassium content of the leaves at both sampling
dates decreased in response to calcium applications; al-
though, nitrogen had no effect on the potassium percentage
of the leaves at either sampling period. The leaf samples
taken early in the season contained more than twice as much
potassium on a percentage basis as those collected late In
the season. Perhaps the best explanation of this is a com-
bination of the mass action effect of the potassium applied
early in the season with luxury consumption by the plant,
and a dilution effect later in the season induced by heavy
vine growth.
The interaction between calcium and nitrogen on the
magnesium content of the leaves at the first sampling may be
attributed to varying degrees of antagonism between the ap-
plied calcium and ammonium nitrogen when the level of either
was changed along with differential growth responses. At
maturity this decrease in the magnesium percentage of the
leaves was not statistically significant. The relative in-
crease in the magnesium percentage of the leaves as the
season progressed, regardless of treatment, was approximately
82
proportional to the relative increase in the calcium per-
centage.
The equivalent shift of the cation composition of
the leaves in response to treatments at either sampling
time is in agreement with the greenhouse findings* That is,
the calcium-equivalent increase in the tissue in response
to calcium applications is much greater than the total mag-
nesium and potassium equivalent decrease in the tissue.
The linear increase in the calcium content of the
tips at the first sampling date in response to the calcium
levels had disappeared by the second sampling date (Tables
21, 26, 30). Perhaps the best explanation of this is that
the young plants were in a more vigorous state of growth
and assimilation than the mature plants. Also, this would
account for the greater percentage of calcium in the tips
of young plants.
Neither the potassium nor the magnesium content in
the tips at the first sampling date was significantly in-
fluenced by any treatment. However, nitrogen treatments
decreased the potassium and magnesium content of the tips
at the second sampling time. This may be attributed to a
combination of a number of factors, including a retardation
of the physiological aotivity of the merstimatic tissues,
differential build up of ammonium ions in the tissue, and a
dilution effect resulting from differential vine growth and
fruit yields.
83
In general, the normal fruits contained considerably
less calcium, potassium, and magnesium than fruits exhibiting
blossom-end rot. The most logical explanation of this Is a
dilution effect, since the mature fruits were approximately
four to five times larger than the ones exhibiting blossom-
end rot (Table 28, 39, 30).
The calcium content of both types of fruit samples
increased linearly in response to calcium treatments. The
curvilinear response of calcium in the mature fruits to
nitrogen may be attributed to antagonism between ammonium
and nitrogen and differential vine growth.
The curvilinear interactions of the calcium and ni-
trogen treatments on the potassium content of both types of
fruits may have resulted from mass action effect of the
hydra ted lime, antagonism between ammonium and potassium,
and dilution due to differential growth responses (Figs. 4
and 5). The same explanation may be given for the inter-
action of treatments on the magnesium content of fruits
showing blossom-end rot (Fig. 6).
SUMMARY AND CONCLUSION
Research was conducted In both the greenhouse and
the field to evaluate the effects of varying calcium levels
on vine growth, yields, quality, sex expression and fruit
set, and the calcium, potassium, and magnesium content of
plant tissues of the Charleston Gray variety of watermelons.
In the greenhouse, plants grown in a basic nutrient solution
containing no calcium developed severe calcium deficiency
symptoms and died within two weeks following transplanting.
Plants grown in 4 ppm calcium began to develop calcium de-
ficiency symptoms in both the tops and roots three weeks
following transplanting, and they grew increasingly more
severe as the season progressed. Plants grown in 8 ppm
calcium showed no deficiency symptoms in the tops, although
slight deficiency symptoms were present in the roots. Plants
grew normally in nutrient solutions ranging from 16 to 256
ppm calcium.
The leaves of deficient plants were dark green in
color, moderately cupped under at the margins, and severely
restricted especially at the apex forming a more circular
type leaf, and the vine laterals were short and very nu-
merous. The root systems of calcium deficient plants were
short, dense, very numerous, and often dark at the apex
indicating death.
84
85
The dry weight of the Tines and the roots, when
analyzed separately, decreased linearly as the logarithms
of the calcium concentration increased in the nutrient solu-
tion. However, total dry weight (vines, roots and fruit)
did not differ significantly among calcium levels.
In the field experiment testing three levels of
calcium (0, 500, and 1,000 pounds of hydrated lime per acre)
and three levels of nitrogen (60, 120, and 180 pounds per
acre), the dry weight of early vine growth increased sig-
nificantly in a linear pattern in response to increasing
calcium levels. Nitrogen did not affect early vine growth
or any other growth measurements taken in this experiment.
Explanations are suggested based on soil test and rainfall
data.
There was a significant linear Increase in early
and total yield in both pounds and numbers of marketable
watermelons as a result of increased calcium levels. The
average weight per melon of the early yield was not affected
by treatments; however, the average weight per melon of the
total yield was increased significantly by increasing the
calcium levels. The environmental factors possibly respon-
sible for these yield increases are discussed. It appeared
that the beneficial effects of calcium resulted from both
an increased supply of calcium and pH changes which may
have directly or indirectly affected the availability of
other elements.
86
Calcium levels in the greenhouse nutrient solutions
had a profound effect on sex expression and fruit set at
the lower concentrations. The ratio of staminate to pistil-
late flowers in. solutions containing 4 ppm calcium was
27.79:1. When the calcium concentration was Increased to
8 ppm the flower ratio dropped to 8.74:1, and It did not
differ significantly as the calcium levels were increased
to 256 ppm. At least 16 ppm of calcium In the nutrient
solutions were necessary for fruit set. In the field the
total number of fruits set Increased in a quadratic fashion
as the calcium levels were increased. Nitrogen had no ef-
fect on the numbers of fruit set in the field. A large per-
centage of the ovaries produced by plants grown in nutrient
solutions containing 4 or 8 ppm calcium turned dark brown
to black in color beginning at the blossom-end, even before
the floral parts opened. All fruits set in the greenhouse,
regardless of the admixture of the nutrient solutions, de-
veloped blossom-end rot within three weeks after flowering.
The percentage of blossom-end rot in the field experiments
could not be associated with treatments. However, the rind
thickness at the blossom-end of marketable fruits decreased
linearly as the calcium treatments increased.
Analyses of data from three fertility experiments
during the 1958 season revealed that the occurrence of
blossom-end rot could be associated with the soil profile
characteristics but not with the different fertility treat-
ments.
87
In the field experiment, the different fertility
treatments tested resulted In no significant Influence on
the soluble sugars, hollow-heart, white-heart, or average
thickness of the rind measured at the center of the fruit.
Analyses of tissue samples from various plant parts
indicated that watermelons absorb relatively large quanti-
ties of calcium, potassium, and magnesium. The greatest
concentration of calcium or magnesium occurred in the older
leaves with the percentages decreasing in the following
order: basal leaves, mid-leaves, tips, stems and fruits.
The potassium percentages decreased in the following order:
fruits, stems, tips, leaves.
Analyses of the tips, leaves, roots and fruits from
the greenhouse experiment Indicated, in general, that as
the calcium concentration was Increased logarithmically in
the nutrient medium the calcium content In the tissues in-
creased and the potassium and magnesium content decreased.
The Increase in the percentage of calcium In the tips and
fruits was linear and the increase in the calcium content
of the leaves and roots was curvilinear, when measured
against the logarithms of the calcium concentrations in the
nutrient solution. Significant negative linear regressions
in the potassium content occurred in the leaves and roots
but not in the tips and fruits in response to calcium levels.
The negative regression in the magnesium content induced by
the calcium levels was linear in the roots and fruits and
quadratic in the leaves and tips.
88
Analyses of tip and leaf samples from both young
and mature watermelon plants from the field Indicated that
the calcium percentage generally increased, and the mag-
nesium and potassium content decreased as the calcium sup-
ply was increased in the soil. The influence of nitrogen
on the cation composition of the leaf and tip samples was
at variance for the two sampling dates; however, any sig-
nificant effect of nitrogen treatments on the cation com-
position of the tissues generally resulted in a decrease
of the particular element as the nitrogen levels were in-
creased in the soil.
On a percentage basis the calcium and magnesium
content of the leaves of mature plants, regardless of
treatment, was approximately double that of the leaves of
the young plants, while the potassium content was approxi-
mately 50 per cent less in the older plants. The calcium
or potassium percentage of the tips of mature plants was
50 per cent less, while the magnesium percentage remained
fairly constant from the first to the second sampling.
Analyses of U. S. Number 1 watermelons and those
exhibiting blossom-end rot revealed that the calcium content
generally Increased and the potassium and magnesium content
generally decreased in response to increasing calcium levels.
Increasing nitrogen levels, however, resulted in a reduction
of both the calcium and magnesium content of the U. S. Number
1 watermelon fruits. The magnesium content of the fruits
89
exhibiting blossom-end rot and the potassium content of
both types of fruits was influenced by calcium and nitrogen
interactions.
The calcium, potassium, and magnesium content of the
U. S. Number 1 fruits were generally lover than the con-
centration of these cations in the fruits exhibiting blossom-
end rot*
It is believed that results of this study may be of
value in evaluating and explaining the occurrence of certain
physiological disorders and poor growth and yield often ob-
tained in many of the commercial watermelon fields in North
Central Florida.
REFERENCES CITED
1. Andrews, W. B. 1937* The effect of ammonium sulfate
on the response of soybeans to lime and artificial
innoculation and the energy required of soybean nodule
bacteria. Jour, Amer. Soc. Agr on. 29:681-689.
2. Anonymous. 1954. Soil survey, Alachua County, Florida.
USDA and Fla. Agr. Expt. Sta. 233-235.
3. Arnon, D. I. 1943. Mineral nutrition of plants. Ann.
Rev. Biochem. 12:493-528.
4. Baver, L. D. 1956. Soil Physics, New York: John
Wiley A Sons, Inc. 3rd. Ed.
5. and Hall, N. S. 1937. Colloidal properties
of soil organic matter. Mo. Agr. Expt. Sta. Res. Bull.
267.
6. Bernstein, L. and Hayward, H. E. 1958. Physiology
of salt tolerance. Ann. Rev. Plant Physiol. 9:1-25.
7. Biddulph, 0., Cory, R., and Biddulph, Susann. 1959.
Translocation of calcium in the bean. Plant Physiol.
34:512-519.
8. Blodgett, F. H. 1915. Plant pathology and physiology.
Texas Agr. Expt. Sta. Ann. Kept. 18.
9. Bonner, James and Galston, Arthur W. 1952. Principles
of Plant Physiology. San Francisco: W. H. Freeman and
Co.
10. Bradley, G. A. and Fleming, J. W. 1959. Fertilization
and foliar analysis studies on watermelons. Ark. Agr.
Expt. Sta. Bull. 610.
11. Brantley, B. B. 1958. Effects of nutrition and other
factors on flowering, fruiting, and quality of water-
melons and muskmelons. Unpublished Dissertation,
Purdue Univ., Dept. of Hort.
12. Breland, II. L. 1957. Methods of analyses using soil
testing. Fla. Agr. Expt. Sta. Dept. Soils Memo. Rept.
No. 58-3.
90
91
13. Burrus, R. II. 1959* Nitrogen nutrition. Ann. Rev.
Plant Physiol. 10:301-328.
14. Carolus, R. L. and Lorenz, 0. A* 1938. The inter-
relation of manure, lime, and potash on the growth
and maturity of the muskmelon. Proc. Amer. Soc. Hort.
Sol. 36:518-522.
15. Cochran, W. G. and Cox, Gertrude M. 1957. Experi-
mental Designs. New York: Wiley Publications in
Statistics.
16. Cooper, H. P. 1950. Effects of energy properties of
some plant nutrients on availability, on rate of
absorption, and on intensity of certain oxidation-
reduction reactions. Soil Sci. 69:7-39.
17. Cunningham, Clyde R. 1939. Fruit set in watermelons.
Proc. Ameri. Hort. Sci. 37:811-814.
18. Dearborn, R. B. 1936. Nitrogen nutrition and chemi-
cal composition in relation to growth and fruiting
of the cucumber plant. Cornell Univ. Agr. Expt. Memo.
192.
19. Duncan, D. B. 1955. Multiple range and multiple F
test. Biometrics. 11:1-42.
20. Eisenmenger, W. S. and Kucinski, K. J. 1939. Mag-
nesium requirements of plants. Mass. Agr. Expt. Sta.
Ann. Kept. 10.
21. Epstein, E. 1956. Mineral nutrition of plants;
mechanisms of uptake and transport. Ann. Rev. Plant
Physiol. 7:1-24.
22. Everett, P. H. and Geraldson, C. M. 1958. Fertilizer
requirements of watermelons. Fla. Agr. Expt. Sta. Ann.
Rept. 326-328.
23. Fiskell, J. G. A., Hortenstine, C. C, Carver, H. L.,
and Lundy, H. W. 1958. Aluminum studies on some north
and central Florida soils. The Soil and Crop Sci. Soc.
of Fla., Proc. 18?166-178.
24. and Robertson, W. K. 1957. Comparison of
broadcast and row fertilization for potatoes on Kanapaha
fine sand. Fla. State Hort. Soc. 70:96-103.
25. Fried, M. and Peech, M. 1946. The comparative effects
of gypsum upon plant growth in acid soils. Jour. Amer.
Soc. Agron. 38:614-623.
92
26. Geraldson, C. M. 1957. Symptoms of nutritional dis-
orders in vegetable plants. Fla. Agr. Expt. St a. Ann.
Rept. 296.
27. . 1957. Control of blossom-end rot of toma-
toes. Proc. Amer. Soc. Hort. Sci. 69:309-317.
28. Hall, C. B., Nettles, V. P., and Dennison, R. A.
1951. Fertilizer requirements for watermelons. Fla.
Agr. Expt. Sta. Progress Rept. (Misc.).
29. , , and . 1955. Fertilizer
requirements for watermelons. Fla. Agr. Expt. Sta.
Ann. Rept. 113.
. •
30. Hall, W. C. 1949. Effects of photoperiod and nitro-
gen supply on growth and reproduction in the gherkin.
Plant Physiol. 24:753-769.
31. Hardh, J. E. 1957. On the calcium uptake of glass-
house cucumbers. Maataloust Aikakausk. 29:238-242
(Hort. Abs. Vol. 28, No. 1419).
32. Hart man, John O, and Gay lord, F. C. 1940. Soil
acidity for muskmelons and sweetpotatoes on sand. Proc.
nraer. Soc. Hort. Sci. 37:841-845.
33. Hartman, John D. and Gaylord, F. C. 1941. Soil acidity
for watermelons on sand. Proc. Amer. Soc. Hort. Sci.
38:623-625.
34. Hartwell, B. L. and Damon, S. C. 1914. The comparative
effect on different kinds of plants of liming an acid
soil. R. I. Agr. Expt. Sta. Bull. 160.
35. Hasler, A. and Maurizio, A. 1951. The influence of
various nutrients on budding, nector secretion, and
yield of seeds of honey plants, especially winter rape
(Brass! ca nanua). Schweiz. Bienen-Z. 74:208-219
(C. A. Vol. 49, No. 4091g).
36. Heslop, Harrison J. 1957. The Experimental Modifica-
tions of Sex Expression in Flowering Plants. Biol.
Review. 32:38-90.
37. Hoagland, D. R. and Arnon, D. I. 1950. The Water-
culture Method for Growing Plants without Soil. Calif.
Agr. Expt. Sta. Cir. 347.
38. Holmes, R. S. 1943. Copper and zinc content of cer-
tain United States soils. Soil Sci. 56:359-370.
03
39. Horn, G. C. 1955. Some factors affecting the accuracy
of the flame spectrophotometrlc determination of mag-
nesium in soils. Unpyblished Dissertation. Univ. of
Fla.
40. Jamison, F. S. and Nettles, V. F. 1940. Phenol ogical
studies on truck crops in Florida. Fla. Agr. Expt.
Sta. Ann. Rept. 86-87.
41. Kimbrough, W. D. 1930. The effect of fertiliser on
the quality of watermelons. Plant Physiol. 5:373-385.
42. Knott, J. E. 1957. Handbook for Vegetable Growers.
New York: John Wiley and Sons, Inc. 36.
43. Langston, Ruble. 1956. Radioisotopes in plants.
Proc. Amer. Soc. Hort. Sci. 68:370-376.
44. Laties, George G. 1959. Active transport of salt into
plant tissue. Ann. Rev. Plant Physiol. 10:87-112.
45. Loehwing, W. F. 1938. Physiological aspects of sex S
in angiosperms. Bot. Rev. 4:581-625.
46. Marshall, C. E. 1948. Ionization of calcium from
soil colloids and its bearing on soil-plant relation-
ships. Soil Sci. 65:57-68.
47. Mazaeva, M. M. 1957. Effect of magnesium fertiliza- >"
tion and its role in plants. Botan. Zhur. 42:571-582
(C. A. Vol. 51, No. 1842g).
48. Meyer, B. S. and Anderson, D. B. 1952. Plant Physiology.
New York: D. Van Nostrand Company, Inc. Second Edition.
49. Meyers, H. E. 1937. Physio chemical reactions between
organic and inorganic soil colloids as related to
aggregate formation. Soil Sci. 44:331-359.
50. Miller, Edwin C. 1938. Plant Physiology. New York-
London: McGraw-Hill Book Company, Inc.
51. Minina, E. G. 1938. On the phenotypical modification
of sex characters in higher plants and other external
factors. C. R. Acad. Sci. USSR 21:298-301 (C. A. Vol.
33, No. 4292).
52. Morazov, A. S. 1938. Effect of sodium chloride and
sodium sulfate on sugar content of melons. Compt. Rend,
Acad. Sci. USSR 21:279-281 (C. A. Vol. 33, No. 3950).
53. Nettles, V. F. and Halsey, L. H. 1958. Fertilizer Re-
quirements of watermelons. Fla. Agr. Expt. Sta. Ann.
Rept. 172-173.
S
94
54. Nightingale, 6. T. 1937. The nitrogen nutrition of
green plants. Bot. Rev. 3:85-174.
55. Over street, Roy and J a cob son, Louis. 1952. Mechanisms
of ion absorption by roots. Ann. Rev. Plant Physiol.
3:189-206.
56. Parris, 6. K. 1952. Diseases of watermelons. Fla.
Agr. Expt. Sta. Bull. 491.
57. Patterson, D. R. and Smith, Oliver E. 1958. High
potash rates boost watermelon yet Ids. Better Crops
42:12-15.
58. Peech, M. and Bradfield, R. 1943. The effect of lime
and magnesia on the soil potassium and on the absorption
of potassium by plants. Soil Scl. 55:37-48.
59. Pierre, W. II. and Bower, C. A. 1943. Potassium ab-
sorption by plants as affected by cat ionic relationships.
Soil Sci. 55:23-36.
60. Porter, D. R., Bisson, C. S., and Allinger> H. W. 1940.
Factors affecting the total soluble solids, reducing
sugars, and sucrose in watermelons. Hllgardia 13: di-
61. Purvis, E. R. and Ruprecht, R. W. 1937. Cracked stem
of celery. Fla. Agr. Expt. Sta. Bull. 307.
62. Reynolds, C. W. and Stark, F. C. 1953. Growth and
fruiting responses of cucumbers to varying levels of
Ca, K, Mg, and N in sand culture. Proc. Assoc, of
So. Agr. Workers. 133-134.
63. Richards, F. J. 1944. Mineral nutrition of plants.
Ann. Rev. Blochem. 13:611-630.
64. Sabinln, 1). A* 1937. La nutrition minerale comme /
facteur of mophogenes. Bull. Soc. Nat. Moscow, Sect.
Biol. 46:67-76 (C. A. Vol. 31, No. 5843).
65. Schmehl, W. R., Peech, Michael and Bradfield, Richard.
1950. Causes of poor growth of plants on acid soils
and beneficial effects of liming: I Evaluation of
factors responsible for acid— soil injury. Soil Sci.
70:393-410.
66. Sharpies, G. C. and Foster, R. E. 1958. The growth and
composition of cantaloupe plants in relation to the Ca
saturation percentage and N levels of the soil. Proc.
Amer. Soc. Hort. Sci. 72:417-425.
95
67. Shear, C. B. and Crane, H. L. 1954. Inorganic nu-
trition of plants with special reference to inter-
action among elements. Unpublished Manuscript, 1-40.
68 • — —i * and Meyers, T. A. 1946. Nutrient
element balance: A fundamental concept in plant nu-
trition. Proc. Amer. Soc. Hort. Sci. 47:239-248.
69 '• . . * » and . 1953. Nutrient ele-
ment balance: response of tung trees grown in sand
culture to potassium, magnesium, calcium, and their
interactions. USDA Tech. Bull. No. 1085.
70. Smith, G. L. and Mohr, H. C. 1953. Effect of dif-
ferent nutrient levels on the yield of marketable
black diamond watermelons, 1949-52. Texas Agr. Expt.
Sta. Progress Rept. No. 1589.
71. Staker, E. V. and Cummings, R. W. 1941. The influence
or zinc on the productivity of certain New York peat
soils. Soil Sci. Soc. Amer. Proc. 6:206-214.
72. Stark, F. C. and Haut, Irvin C. 1958 mineral nutrient
requirements of cantaloupes. Md. Agr. Expt. Sta. Bull.
73. Stuckey H. P. 1924. Watermelons. Georgia Agr. Expt.
aia. £1111 • 143.
74. Taylor, George A. and Smith, Cyril B. 1957. The use
of plant analysis in the study of blossom-end rot of
tomatoes. Proc. Amer. Soc. Hort. Sci. 70:341-349.
75. Taubenhaus, J. J. 1921. Blossom-end rot: division of
Plant pathology and physiology. Texas Agr. Expt. Sta.
Ann. Rept. 17-19.
76. Thompson, A. E. 1955. Methods of producing first
generation hybrid in seed spinach. Cornell Agr. Expt.
Sta. Mem. 336. *
77. Tibeau, M. E. 1936. Lime factor in utilization of
minerals by hemp. Plant Physiol. 11:731-747.
78. Tiedjens, V. A. 1928. Sex ratios in cucumber flowers
as affected by different conditions of soil and li^ht.
Jour. Agr. Pes. 36:721-746. ^
?9# J^S' A1*ef!; \952# ^^ological bases for assess-
ing the nutritional requirements of plants. Ann. Rev.
Plant. Physiol. 3:207-228.
96
80. USDA. 1958. Vegetables-fresh market annual summary
acreage, production and value of principle commercial
crops by season groups and states with comparisons.
50-51 • '
81. Waksman, Selman A. 1952. Soil Microbiology. New
York: John Wiley St Sons.
82# 5Ialker# M* N» 1931 • Investigation and control of
diseases of watermelons. Pla. Agr. Expt. Sta. Ann.
Rept. 115.
83. Wilkins, Louis K. 1917. High calcium content of
some cucurbit vines. N. J. Agr. Expt. Sta. Bull. 310.
84. Wood, J. G. 1954. Nitrogen metabolism of higher
plants. Ann. Rev. Plant Physiol. 5:1-22.
85. Woodard, Otis. 1954. Factors influencing white-
heart in watermelons. Atlantic Coast Line Agr. and
Livestock Topics. 6: (April) 3-4.
86. Wright. K. E. 1937. Effects of phosphorus and lime
in reducing aluminum toxicity of acid soils. Plant
Physiol. 12:173-181.
APPENDIX A
DETAILED SOIL TEST RESULTS BY PLOT
98
TABLE 31
THE pH AND THE POUNDS PER ACRE OF AVAILABLE NUTRIENTS
FROM SOIL SAMPLES TAKEN IN WATERMELON BEDS
FROM ALL FIELD PLOTS ON APRIL 1, 1959
Treatment pH
CaO
MgO
p2°5
K20
NO.
CaO
N0
CaO
Nl
CaO
4
cai
%
cai
2l
Cal
Ca?,
N2
Ng
Ca2
Nl
Ca2
N2
CaO
N0
CaO
Nl
CaO
4
C»l
N0
"al
!l
cai
N2
Ca2
N0
Ca2
Nl
Ca2
4
CaO
NO
CaO
Nl
CaO
N2
Cal
Nn
Cai Nl
Cal
N2
Ca2 N0
Ca2 NX
Ca2
N2
CaO
N0
CaO
Nl
CaO
N2
Cax N0
Cai
Nl
cai
Ca2
N0
Ca2
Nl
Ca2 N2
4.9
103
Replication
73
I
85
229
L
5.1
34
52
85
210
L
5.0
137
97
93
296
M
5.4
434
73
88
191
L
5.2
562
97
83
296
L
5.7
652
62
83
223
L
5.9
1395
52
119
262
L
6.0
2000
52
99
210
L
5.8
1286
83
85
197
L
4.8
68
Replication
52
II
99
216
VL
5.2
68
52
83
184
L
4.8
68
62
96
235
M
5.4
434
62
68
310
L
5.5
698
83
96
296
L
5.5
562
62
116
255
M
5.8
2000
124
76
296
L
5.9
1772
83
101
338
M
6.2
2224
73
90
216
L
5.2
Replication
698 216
III
90
352
VL
4.8
350
152
83
269
L
4.8
308
182
78
248
VL
5.2
350
97
76
204
L
5.3
562
97
108
262
M
5.1
562
152
67
210
L
5.5
837
97
93
242
L
5.6
932
62
67
165
M
5.5
2910
199
96
262
VL
4.8
68
Replication
62
IV
99
255
VL
4.8
137
83
108
242
L
4.7
68
52
76
210
L
5.1
273
62
76
197
VL
5.5
789
83
70
216
VL
5.2
741
73
96
216
L
5.9
1030
73
101
248
VL
5.8
1340
62
128
210
M
5.7
1449
111
93
235
L
99
TABLE 32
THE pH AND THE POUNDS PER ACRE OF AVAILABLE NUTRIENTS
FROM SOIL SAMPLES TAKEN ON EACH SIDE OF THE
BED FROM ALL PLOTS ON APRIL 1, 1959
Treatment
pH
CaO
MgO
P205
K20
N03
Replication
I
CaO N0
4.7
34
41
54
30
L
CaO N,
4.9
68
52
55
47
L
CaO N2
4.7
34
62
51
65
M
CaX N0
5.1
137
62
46
65
M
Cai Nx
5.1
308
97
49
59
M
Cai N2
4.8
68
52
52
59
M
Cao Nq
5.2
239
62
52
47
M
Ca2 Nx
5.3
239
73
61
24
M
Ca2 Nj
5.0
103
41
Replication
49
II
59
L
CaO N0
5.0
34
31
46
41
VL
CaO Ni
4.9
68
41
54
41
L
CaO N2
4.8
34
31
45
47
VL
Cai N0
5.0
68
41
46
35
L
Cai Nx
5.1
137
97
44
47
L
Cax N2
4.9
68
41
51
35
M
Ca2 N0
5.0
171
83
43
53
L
Ca2 Nx
5.0
137
62
46
53
L
Ca2 4
5.1
103
41
Replication
48
III
41
VL
CaO N0
5.2
652
253
44
152
L
CaO Nx
4.8
137
138
51
127
VL
CaO N2
4.9
239
216
48
172
VL
Cai N0
5.0
103
97
49
102
L
Cat NV
5.0
171
83
51
47
VL
Cai N2
4.9
205
166
45
77
VL
Ca2 N0
4.8
103
62
54
65
VL
Ca2 NX
4.8
103
41
48
41
VL
Ca2 N2
4.9
434
166
Replication
44
IV
90
L
CaO N0
4.7
34
52
55
53
VL
CaO Ni
4.7
68
52
60
59
L
CaO N2
4.8
68
62
60
24
VL
Cax N0
4.9
68
31
55
30
VL
Cai Nl
4.9
137
83
49
59
VL
Cai N2
5.0
68
41
55
35
VL
Ca2 N0
5.1
103
41
57
30
VL
Ca2 Ni
5.1
103
52
49
30
VL
Ca2 N2
4.9
103
73
51
41
VL
APPENDIX B
ANALYSES OF VARIANCE TABLES
101
n
w
9
3
«
25
01
«
01
CM
o
o
o
o
o
o
o
•
•
•
o
©
•
o
«
•
s
m
to
CO
o
o
m
o
•
•
•
o
o
*
o
•
«
00
o
o
w
o
ft
•
•
•
o
H
*
»
o
to
a
*
o
to
o
•
•
•
o
10
o
*
*
CO
to
GO
o
•
•
t»
o
01
0
►
©
o
in
w
01
OB
B «
O •*»
•H C
88 (H
« A
O
4
u
©
fa
to
n
1-4
a
o
H
ft
©
TS
oS
s
bfl
0)
©
E
*J
OJ
fl
G
C
w
c
08
§
M
•
o
•H
XJ
44
©
8
no to
•H
H
0
© CO 00
g
©
•H
© • •
8
fc. 01 W
•H
c
M
M
OJ
o
a) as »
#
■H
8
"B iHiH
*
C
4
08
eg e8
to S B
%
A
OJ CO"
0 0
-B
i-t
•
B
efl
9
>
O
8 t-t i-t
©
A
E
a) 0 «
ft
8*
^
> ►
+»
IC 0 0
1ft
e
rH H
O
E
-a
L
•
A
©
OlOH
o
■♦»
W
4h O O
09
• •
t»
Xt
a
ooo
a
©
Pi
•H
8
OS
O
&
o
8
0
0
ft
ft
0 OS c8
E
©
0
« co en
# 08 fit
102
TABLE 34
THE ANALYSES OF VARIANCE OF THE OVEN DRY WEIGHTS OF
VINES, ROOTS. AND TOTAL WEIGHT (VINES, ROOTS,
AND FRUITS) OF GREENHOUSE EXPERIMENT
Degrees of
freedom
Mean
square)
9a
Source of
variation
Vines
Roots
Total weight
(vines, roots,
fruits)
Replication
Ca level s*
Linear
Quadrati <
Cubic
Residual
Error
3
6
1
3 1
1
3
18
160.7
617.9
2340.6**
33.7
434.4
224.6
135.3
1.66
4.05
9.29*
4.31
6.93*
1.26
1.37
440.9
496.5
6.5
917.1
1229.1
277.8
304.7
Total
27
MftV^S
•»«»«•
♦Significant at 0.05 level, **signif leant at 0.01
level.
aVariance ratio for 1 and 18 degrees of freedom:
F at 0.05 level equals 4.41
F at 0.01 level equals 8.28
^Effects were determined by using log x as the in-
dependent variable, where x equals the concentration of
calcium in the nutrient solution in ppm.
103
TABLE 35
THE ANALYSES OF VARIANCE FOR THE NUMBER OF STAMINATE,
PISTILLATE, AND RATIO OF STAMINATE TO PIS-
TILLATE FLOWERS PRODUCED IN THE
GREENHOUSE EXPERIMENT
Source of
Degrees of
freedom
Mean
squares
variation
Staminate
Pistillate
S:P ratio
Replication
Ca levels
Error
3
6
18
1.72
8.89**
0.62
0.44
3.23**
0.22
0.11
3.04**
0.16
Total
27
«»«•«»
**Significant at 0.01 level.
Variance ratio for 6 and 18 degrees of freedom:
F at 0.05 level equals 2.66
F at 0.01 level equals 4.01.
104
©
co
9
fa
O
n
0)
fa m
3 o
c-o
a fa
8
©
fa
O
»
©
fa so
3 ft
to
J?
c
©
fa
O
v<
«
© n
fa ©
2 ►
9 sJ
o<®
«H
©
co
o
*
M
JT
M
cO
u
» © © « CM *• ©
nnooooo
O O H O O O O
• ••••••
oo oo o o o
CM © HCM »©^
OH00O
• • •
OO o
*
*
to m ©
1-4 CO t'
• • •
O r-t CO
HOIR
CM1* ©
O © H
• • •
o OO
Cit'tOt-
© "tf -* H
O C-
CM
o o
© CM l> ©
in o ho
o oo o
• ♦ • •
o o o o
^oo^hooo
© CM Hfr- H© CO
• ••••••
oooo OO o
CM © © AHHOO
HO©H OHO
O © 01 o o o o
• ••••••
o o oo oo o
^ Q ft CM fc-O ©
• ••••••
O H© HOO O
© 0> © T* CO CO ©
O £> © © © O H
• ••••••
O H 0» O O O O
# i
H © © O CM CO O
W O OOH© i* CO
• ••••••
© © © o^» o o
HO
o
E
to o
©•8
© 9
^©
fa
©«_,
4*
O
8
e c«
CO >
CO ©
HHHC0
©
03 O
C H H
OP ♦> cJ
«H eo fa at S
■*»H oJ fa 0*3
eO © c9 tHtI
© ► c cop m
•h ©-5 a 3 © fa
HH.-lo'oa; o
ft
o a
as ©
CM
H
0)
+»
O
H
2
9
*
*
9
H
P
at
•H
fa •
£ft
ft
V
B 8
© H
rs
E 8
9 O
ftH
© V
T3 3
BH
#6
•H e
■
OS
i
9
•«
Xii»
s
■*» B
9
fa
fal
St
9
%j
M S
o
8
W
O 9
WH©
©^ CM
HA
« •
•
•♦»
fa^CO
8 B
© BO
01
•H-H
"3
H
00
3 §
•
© 3
3
H
H ©«©•
>»-H
•
i
©
p 8
►
-o
H
©
SHH
X> CO
© ©
H
a ©
©
>
►
8
H
H ©
©
■HW
O
•
ftr-t
fa
g8
o
O© H
© s
<~ o o
♦» ©
*»
•
•
©T«
9)
ooc
•a •»»
<H
«0
*>
+»«* *
© fa
c
CO CO
a)
fa -P
•H
fa
© 8
©
*s
<«
0
■ 8
E
s
(0
>
feet
e oo
00
«
*
a
p
m
H
g
©•
•
105
TABLE 37
THE ANALYSES OF VARIANCE FOR CALCIUM, POTASSIUM, AND
MAGNESIUM IN THE FRUITS OF THE
GREENHOUSE EXPERIMENT
Source of
Degrees of
Mean
squaresa
variation
freedom
Ca
I
Mg
Replications
Ca levels*
Linear
Quadratic
Cubic
Residual
Error
3
4
1
1
1
1
12
0.001
0.037
0.141**
0.003
0.000
0.004
0.001
0.10
0.14
0.05
0.01
0.38
0.04
0.23
0.002
0.010
0.040**
0.000
0.001
0.000
0.002
Total
19
♦♦Signif leant at 0.01 level.
aVariance ratio for 1 and 12 degrees of freedom:
F at 0.05 level equals 4.75
F at 0.01 level equals 9.33
"Effects were determined by using log x as the in-
dependent variable, where x equals the concentration of
calcium in the nutrient solution in ppm.
00
3
%■? w
05
^Iflrt
>>3 cd
bOH
&
^ 01 00
(H CO 00
in o oo
CO 00 ©
OOHfH
HiHCD
• • •
CMCMO
hco co
W i-IW
• • •
cm ^ a
CM
in m t-
eo •# co
o> ©cm
in co in
t» r-4H
t>on
• • •
CO o o
oca h
H CM
oo m in
• • •
HO 05
CO CM 00
CO
*
moo t> o> in ^ o co
00 Tf t» i> o> ^ cm i* o co o co co
H H H
O 00
CO <#
t»CM
CO O)
CO
CM CM
• •
cm »n
HiH
«>H
oco
CMH
*
05M
C-C0
*
#
*
m co
• •
COr-t
*
m co
• •
CO CO
in co
cm
in cm
CMO
iHt*
CM
in o
• •
CM 00
CO 00
• •
CM T^
00 ^T
fHCM
00 CO c- co©^
CMC0OOC0H
CO O CO t- Q
t* ao co oo^w
• •••••
ho a in -# m
1HH1H
WO CO CO coco
• •••••
in o co co in m
^ oo o in o»oo
OOHOOOO
CM CM"* Oi 00 OS
h h co<# in
CO O <cF 00* 01
1
• •••••
1
O O CO * t> 00
1
H H
* © nt-^HCDO)
OC0 HOC0IOHH
t-* co in win in
co oo
colH^i
' C 3
CD *4
E ©
*» r»»
a>o
E
H
COCO
HH
S 3
© © C Ob
■H -HO JJ Of Cf E
♦2 - . *2 ^ * * * * * •
rt C tU aJ ♦» o
CD "C3 tO © tJ rt r-t >
c «i p c 3 s, ^a^iJoto-H
•H3S*«H3©aJdaJ «T *»
hiff^h)of*>cooo « ©
■H C h ©
S
106
m
co
H
C8
O
H
CD
O
• ••
O B
O
at «
i
C«M
a)
© Cm
•H O
Cm
•H »OJ CO
c »^in
bp © • •
•Hfc* 00
as ho
• a> co as
*CO 3 3
HHCrC
CD CD CD
© CiHH
H 3 CD CD
> ►
in r-l CD CD
O Hrt
OOIOH
Cm O O
*» • •
rt O O O
•H
4* ♦» «* ♦»
g at 4 «
•S cp^1^
Cm ©
5
00 aj
♦ >
107
• *»
O <D
* «
%
C ca
l> lO i-t
0> l>
'f 00
o 0) t- oo co o
1
CO
• • •
• •
• •
• •••••
1
i
H •♦»
t- <* CO
"f o
fc- lO
lOHOiOO^
1
11
Q«H
o 01
lO ^
HiH
(HO CO OOOi
PM
"* rHCM
CO 01
9) ©
H %4
H
MM
I
3h
|
ie
O +»
m o
lO © CO
o ©
iH ©
<# oi o in coo
1
H as
05 i-
• • •
• •
• •
• •••••
1
OH
0
0> HCO
00 CM
to ©
O H IQ 01 O O
1
CO a; «
i-tTJ
© co to
CO CM
01 CO
_. H
-O c
H
l-l
H
td •»©
1
3S*
V2.
ggg
m
a a a
m a
o o i as
« ©
§x§w
« i
#
•O fi 1
00 CO CO
<* o
©*
fcO £> O l> HH
0.OWH
CO HW
CM T*
HO
O O O CO 0101
1
■HOW
• • •
• •
• •
• •••••
I
BS H ©CO
OOH
CC H «9
A O
ooo
H O
OO
o o OO OO
1
••
fe««BH
+» H
A3
■
O
CO P W p 25
•5
H SoOtf W
^
©
3 H H
pftifcafi
E
©
CJ
T3 • O
c
Cx
co
a? o a ©a
■H © *»
fc» to ©
CO oi
© CO
o o
CO CM HO ©^
WHO ft.
• © 1
©HP
ooo
o o
•HOO#H*©
1
U
a
25 co w
ssaa cs a
< 33 a, a
• • •
ooo
• •
oo
• •
oo
• •••••
oooooo
1
1
O
« OS CO
WH MP
a <:§ §h
Sab
< ** -p
© • •
fc. ^ 00
© ■ to
UK O H S
©
,© 0)
t> 0»«O
(0 iH
00 CO
OHfOHU)
•
•© HH
ed ca
co 3 3
BE ©CO © H
H CO CO H
3 XI
O ^ CM
© CO
«# CO
O O r-JiHCO CO
1
iH
ih o* a*
H H
• • •
• •
• •
• •••••
1
©
© ©
3: <} O
O 1-4
HO©
o o
o o
© o o OOO
1
►
-0
0> ©
09
•
CHH
a © ©
CO H
\&
> ►
co a
to
rH © ©
a co up
O
H iH
g§Hi
u
o
•
O
O tO H
a%%
■
09 ©
1
1
+>
«H O O
• •
5 aco
© TJ
01
hh:i
Hrt*
H»H»-liH
CO
OOO
© «
CO CO 00
1
co co
10
•H
>HC0
b ©
t-iH
CO
V
<♦» •♦* *»
a
t»0 m
E
fe P 25
© <M
CO
c
O 25
H
CO QC
P
-a
©
h
O
0
H
Cm
s
a
co a
■
©
© B
(h O
© (4
H
B
3
^9
S
H
H ©
h3h3 C'Gf b
bO
•H
li
a-<-»
«■
4»H2!
H
L
O T3
h to B
U <3*>
©
09
CD
's
Ch B
H ttt» B
Ibl
aSfc,©X^XXO©
•
>
o o
■p^ fi 3
© -a to «
H >
.. <
H
0} ©H
E (9 O
E C3 U
H O? h3 CA© H
© V
©0JE©H3*-H3©
ce) <c c9 rt *»
sd
© CO
THlMvH^a'4)i^ai4>uuuo « ©
(H
w
U -H
H © as co
H
a
U 9
CO
3 J-
P. o ©O
S
N
#£
+»
O CO
1 CO ►
«H(.
5^ ,
0
a: AH
H
108
2
3
9
9
OB
0.
§
«H
•♦»
u
o
£
«
M
•
u
©
0
cc
i
©
H
o
1
©
£
86
«
>
V
0
0
H
fa
©
«4
M
09
©
a*
i
©
o
B
(II
i
X
%
e
a
n o
© T3
Q> ©
In ©
bfifc.
©Cm
P
«H S
o ©
«H
83
a**
© flS
0)
►
0.016
0.001
000*0
X00*0
0.001
0.000
HOI "<* CO CM
OOOOO
OOOOO
. . • . •
OOOOO
0.91
0.36
0.810** 0.09
0.005 0.02
0.01
1.76
IO H O CO CO
lonnoto
• • . . .
OOOOO
0.006
0.136
0.001
0.022
0.046
0.087
0.103
0.013
0.034
.051
.027
.115*
.011
.010
.002
#
OlHC&Tf t-
fiOHOO
OOOOO
• . . • •
OO
OO
OO
OOOOO
<0O
HO
• •
.20*
.55
C001
CO o
. .
an* to oio
OOO HOI
• . . . .
o o
HO
OO
OOOOO
00 o
• •
« *
* *
00 01
0><0
. .
•
*
00 CO
• •
Hr-t CM tO CO
^ OO OH
. • . . •
on
0> CM
H
HO
OOOOO
OMH H CMjH H *JH ri r-< i-t
01
c
©
HS525S5"
crar
© © fa ox***
fefl © TJ OS
o c a u
<0 © © oS
O O O O fa
o
g
io
CO
01
o
H
•
H
«
►
©
H
H
O
•
• •
O
■
O
-**
XI
©
©
©
<*>
E
C
u
03
O
*M
«H
o
V<
«H
©to CM
s
©01 CO
bfl
8) . •
•H
fa"«t>
at
w
*
© » 00
*
-© i-tr-i
a ©
%
^33
H
01 ©•©•
©
© «
►
"O
©
CHH
© © 9
H
► ►
to
H © ©
O
HH
•
fa
o
OIOH
Cm OO
*»
• .
©
OOO
•H
•♦»
♦»♦> V
fl
© ^ ©
oj
c
o
M. A
•H
S
•H
«H
9
t
CO
©
*
►
109
2
00 o
op
o 5
• •
o o
ON
oo co
• •
o o
oo
oo
• •
oo
oo
oo
• •
o o
OS 00
CO o
• •
o o
in to
HO
oo
• •
oo
*
iHH
oo
oooo o
o oooo
o o o o o o o
*
0)O
t- w
• •
OO
co to
OH
OO
co ooH-tf oo
O CO CO O iH
• • • • •
o oo o o
HH<0OtS
HOO O O
©oooo
o o o oo o o
«
00
CM
o
• •
oo
00 «o
c-o
• •
OH
in t*
• •
CM O
CM
0>iH
00 ©
oo
• •
o o
* #
* *
CO 0>
o m
• •
in ,h
* *
CO w
• •
t-o
CM CM
•HO
coo
oo
• •
oo
HCM
HO
H t> C-CO CM
cm o in h m
o ooo o
• • • • •
oooo o
0) ooo o
cm o o m ih
oo oo oo o
oin
• •
oo
<* t- m o o
• • • • •
HOCMCM H
coooH'-'H^H'
CM
83
B
o
H
■*»
J
o
H
•*»
£- rt
■** § rt c
G 3 OQ
©h c a
a oh 3
o fl
h o hjJ o?or
hss assess
H-PH J ©J V»J Of
H «» « H S
P»©0 2 H
« u
& Sis 2 « x m ►<
W O T3 rt
O C rt fc,
b H 3 ©
hJc/^G?
rt w rt CD
O CJ OO b
o
fa
c
m
CO
©
o
rt
o
5
§
rs
0
©
fa
rt
•*»
o
H
H O
H OB CO CM
C ©CM 00
bO (fi • •
H fa*C*
oo to
* © ■ CO
# V3 r4H
% * 3 3
H CM 0*Cf
© © ©
© Q HH
H rt © ©
m ho©
O r^r-A
• fa
o ©m f<
«-i oo
♦j • •
rt ooo
H
•♦* 4* •*» 4*
§ £ * *
«-. o
i
3 t
oo rt
110
El)
J><
• M
CD
4*
M
«H
E
c
OS!
1
H
1
i**
n
u
o
fcl
•
o
09
a
o
c
1
0
X
09
1
I
c
H
«
O
£
tt
b
0
«4
«
a
i
cd
O
0
SS
4h
O
6
» O
© «
o ©
5* ©
bflt,
JC
<-. c
e e
H
ss
kt
O aJ
0)
►
mo
OH
o o
• •
o o
CM t-
01 CO
• •
oo
oi in
OO
• •
OO
OlH
OO
OO
• •
OO
00 l>
O H
• •
OO
CO 00
OO
OO
• •
o o
*
1H1H
m o
OO
• •
O o
Si
-*m
OO
• •
OO
*
(OO
* H CO
t- N kO H H H
oooooo
o o o o o o
• •••••
oooooo
m co © o oi co
©corn ho oi
OJO HO HOHOO O
#
*
CO o
t>©
OO
• •
o o
<n h
OO
* *
in oi
• •
OO
« oi
T*«0
OO
• •
OO
HOI
OO
• •
OO
*
H-*
OO
OO
• •
o o
*
01 c-
OH
• •
OO
* *
in o
OO
OO
• •
OO
t-H^OHlO
0000)00
oooooo
• •••••
oooooo
-* OO
OOHO O O
oooooo
oooooo
• •••••
oooooo
n H 2> CD H«
OOO HOO
• •••••
oooooo
<*©
HH01 HO H
OOOOOO
oooooo
• •••••
oooooo
CUjH H CM H H •>*
Hr^rii^
COW
§
H-t»
-P c
21
•rtf
H «
P. ©
« U
at h
4*
Mb
3 ©'a
t-t C cS
OH 3
o s
H O
C (h ett +* fej
©dljOXXJXX
ocdh ja^a^c
_fc,H3©««rtcartH
HjCJ^JCfOOOOH fci
d h q AO
o a *
o
H
©
©
O
o
■»»
d
I
H
*-,
H
H
«9
©
©
H
m
o
•
o
E
O
•O
©
©
E
u
u
O
wcooi
©M oo
© • •
© » 03
sis
oi &o«
© ©
§HH
© ©
► ►
H © ©
HH
L
©in h
Cm O O
OOO
f
©
o
c
a
IS
d at
fa fa
BIOGRAPHICAL NOTES
Willie Estel Waters was torn September 10, 1931, in
Smithtovn, McCreary County, Kentucky. He received his ele-
mentary education in the public school of Smithtovn, Kentucky,
He was graduated from McCreary County High School in 1950.
He entered Cumberland Junior College in September,
1950, and was graduated in May, 1952. He entered the Uni-
versity of Kentucky the same year and was graduated in June,
1954, with a Bachelor of Science Degree in Agriculture.
He married Mary Elizabeth Sunder of Sanford, Florida,
in May, 1952.
From June, 1954, to December, 1954, he worked as an
Assistant County Agricultural Agent in Perry County, Kentucky.
He served with the United States Army Medical Corps from
December, 1954, to September, 1956.
He entered the Graduate School of the University of
Kentucky in 1956, and completed the requirements for the
Master of Science Degree in Agriculture in January, 1958.
He entered Graduate School of the University of Florida in
February, where he has since been working toward the degree
of Doctor of Philosophy.
He was employed as a research assistant by the Uni-
versity of Kentucky Agricultural Experiment Station from 1956
111
112
to 1958 and by the University of Florida Agricultural Experi-
ment Station from 1958 to 1960.
He is a member of Alpha Zeta, Gamma Sigma Delta, Phi
Kappa Phi, and an associate member of the Society of Sigma Xi.
This dissertation was prepared under the direction
of the chairman of the candidate* s supervisory committee
and has heen approved "by all members of that committee. It
was submitted to the Dean of the College of Agriculture and
to the Graduate Council, and was approved as partial ful-
fillment of the requirements for the degree of Doctor of
Philosophy.
January, 1960
7 iQ /wx-vr^-t
Dean, College of Agriculture
Dean, Graduate School
SUPERVISORY COMMITTEE:
AGRI-
CULTURAL
LIBRARY
UNIVERSITY OF FLORIDA
3 1262 08553 7800
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11