EVERETT ET AL: PHOSPHORUS—COPPER—WATERMELONS
155
PHOSPHORUS AND COPPER EFFECTS ON GROWTH AND
YIELD OF WATERMELONS
P. H. Everett, S. J. Locascio,
yields of some crops are reduced. The purpose
of the work reported here was to evaluate fac
torial combinations of P and Cu rates and to
determine if these two elements interact in their
effect on growth and yield of watermelons.
AND J. G. A. FlSKELL1-2
Abstract
The
field
experiments
Gainesville, conducted
at
Immokalee
on virgin
and
flatwood
soils,
Experimental Procedure
factorial combinations of different rates of cop
per
and
105
Field experiments were conducted at Immo
kalee in the springs of 1965 and 1966 using
"Charleston Gray" watermelons as the test crop.
In both experiments the field plots were located
Phosphorous rates of 157 and
on recently cleared virgin Immokalee fine sand
phosphorus were
evaluated
for
their
effect on growth and yield of watermelons.
At
Immokalee, there was a linear increase in yield
with
phosphorus
(P)
pounds per acre.
applications
up
to
210 pounds per acre gave no further yield in
crease
and
there
was
a trend
toward
reduced yields at these high P rates.
also
increased linearly
as
slightly
The yield
the copper rate
in
creased from 0 to 4 pounds of metallic copper
(Cu) per acre.
were
In one experiment (1966) yields
significantly
affected
between P and Cu.
by
the
interaction
The addition of one of these
elements without the other resulted in no signifi
cant
yield increase.
But with the
both the yield increase was
At
Gainesville, only
the
addition of
highly significant.
main
effects of P
and Cu rates significantly influenced
yield.
However, a trend for an interaction of these
elements occurred.
For example, maximum yield
with 0.5 pounds of Cu per acre was obtained
when the P rate was 70 pounds per acre. But
with 4 pounds of Cu per acre the highest yield
was reached with 140 pounds of P per acre.
Introduction
The authors, in previous work (5, 6, 7), have
reported a watermelon yield response to increas
ed levels of both P and Cu.
However, in these
experiments P and Cu were studied separately
and information was not obtained on the effect
of
combinations
of the
two elements on
yield.
There is evidence in the literature (1, 2, 3) that
under
certain conditions
increased
applications
of P may decrease the plant absorption of cer
tain
minor
elements
to
such
an
extent
that
lAssociate Soils Chemist, South Florida Field Laboratory,
Immokalee; Associate Horticulturist, Department of Vege
table Crops; and Soils Biochemist, Department of Soils,
Florida Agricultural Experiment Stations, Gainesville.
2Florida Agricultural Experiment Stations Journal Ser
ies No. 2524.
having an initial soil pH of 4.4. Lime, at a rate
equivalent to two tons per acre each of dolo
mite and high calcium limestone, was broadcast
and disked into a depth of six inches.
Factorial combinations of three rates of Cu
and five rates of P were evaluated each year.
The copper rates were 0, 2 and 4 pounds of
metallic Cu per acre in combination with 0,
52, 105, 157 and 210 pounds per acre of P.
Field plots were arranged in randomized block
designs with there replications of each treat
ment. The plots were seeded in late January
of each year. Each plot contained five hills of
watermelons with a plant spacing of 3' x 10/
All plots received a uniform application of
120 pounds of nitrogen (N) and 200 pounds of
potassium (K) per acre. The N was derived
from ammonium nitrate and ammonium sulfate
(1:1.62 ratio) and the K from potassium sul
fate. Various complete fertilizers were formu
lated by mixing the N and K source materials
with appropriate amounts of superphosphate to
give the desired rates of P. Copper was added,
as copper sulfate, to the various fertilizer form
ulations to give the desired rates of Cu. These
complete fertilizers containing N-P-K and Cu
were applied in three equal applications, each
being equivalent to 1000 pounds per acre.
Be
cause of excessive rainfall during the 1966 ex
periment the plots were side-dressed with an
additional 20 pounds of N and 66 pounds of K
per
acre.
In both experiments the soil in the plot area
and the superphosphate used in the fertilizers
were analyzed for their Cu content.
In 1965 the
soil and superphosphate contained approximate
ly 1.0 and 20 ppm Cu, respectively. In 1966
FLORIDA
156
STATE
HORTICULTURAL
these values were 1.5 ppm Cu in the soil and
9.5 ppm Cu in the superphosphate.
SOCIETY,
Table
1.
Main effects of phosphorus rates on
early vine growth and marketable yield
Early vine-growth was evaluated by measur
of watermelons at Inunokalee.
ing the length of the main runner approximately
seven
weeks
after
planting.
Yield
P
data were
Tons
of melons/A
lb/A
1965
1966
0
15.6
3.2
16.6
52
18.5
20.3
37.9
105
23.5
22.0
39.1
157
21.1
19.6
39.4
210
22.4
20.3
39. Z
-
rates
compiled for the weight and number of market
able melons per acre and for the average weight
per melon.
At Gainesville, in 1966 a 2 x 4 factorial ex
periment
was conducted
to compare
two
rates
of Cu in combination with four rates of P for
F value:
their effect on yield of "Charleston Gray" water
melons.
The Cu rates were 0.5 and 4.0 pounds
of metallic Cu per acre
and the P rates were
1966
Vine
P effects
growth
and
Vine length (in.)
1966
cubic in 1965** and 1966**.
watermelon
yield
increased
0, 35, 70 and 140 pounds of P per acre derived
quadratically with increased rates of applied Cu
from ammoniated
in both years
superphosphate
and diammo-
The plot
(Table 2).
The greatest response
occurred between the zero and the 2 pounds of
nium phosphate.
area was
located
on
virgin
Leon
Cu per acre rates.
The yield with 4 pounds of
fine sand and the watermelon plants were grown
Cu per acre was significantly higher than with
on raised beds nine feet apart with plants spaced
2 pounds of Cu per acre in 1966 but not in 1965.
five feet apart in the row.
The treatments were
The yield increase
obtained in the two experi
arranged in randomized blocks with four repli
ments resulted from an increase in number and
cations.
size of melons with the higher rates of both P
The soil was
limed
at a rate
equiva
lent to three tons per acre on December 2, 1965.
and Cu.
Complete fertilizers were formulated to give the
applied was significantly better than without P.
The
early vine-growth
where
P was
desired Cu and P rates with the N and K held
However, growth was not increased by P rates
constant.
higher
The N was derived from ammonium
than
52
pounds
per
nitrate and the K was derived equally from sul-
was it reduced at higher
fate and muriate of potash.
acre,
but neither
P rates, as was the
case with the yield.
Differences in early growth
a total of 130 pounds of N and 108 pounds of
between the
4-pound
K per acre from this complete fertilizer.
Beds
not observed but growth at both Cu rates was
fertilizer
much better than the growth when Cu was not
were
made
up
and
one-half
All plots received
of
the
was banded in the bed on March 4, 1966.
melons were planted on the same day.
maining
about
one-half
12"
of the
from the
fertilizer
row center
was
Water
The re
banded
on April
28.
2
and
rates
of
Cu
were
added.
In 1966 both the early vine-growth and mar
ketable yields
(Figures 2 and 3)
were signifi
cantly affected by both P and Cu rates.
With
of 23-0-22 were applied on May 11 and on May
out P, increased rates of Cu had little effect
on growth, but with the addition of 52 pounds
23, 1966.
of P per acre there was a significant increase
Two side-dressings of 150 pounds per acre each
in growth at the 2 and 4 pounds rates of Cu.
Rates of P higher than 52 pounds per acre re
Results
sulted in no increase in growth at that time with
The main effects of P and Cu rates in 1965
and 1966 at Immokalee are shown in Tables 1
and 2. In both experiments the yields increased
linearly up to 105 pounds P per acre. However,
in 1965 the yield increase between the zero and
52-pound rates was not significant, but in 1966
there was a highly significant yield increase
from the addition of 52 pounds P per acre.
Dur
ing both years the yields at the 157 and 210-
pound rates were less than at the 105-pound
rate. This reduction in yield at the higher P
rates was significant in 1966 but not in 1965.
any of the Cu rates.
The interaction effect of
P and Cu on yield was even more pronounced.
Table 2.
Main effects of copper rates on early
vine growth and marketable yield of
watermelons
Cu
-
rates
lb/A
at
Immokalee.
Tons
of meIons/A
1965
1966
Vine
length (in.)
1966
0
16.4
7.0
27.2
2
21.2
21.6
37.9
4
23.2
25.8
38.6
F value:
Cu effect
is
quadratic
in
1965 and 1966**.
EVERETT ET AL: PHOSPHORUS—COPPER—WATERMELONS
The addition of one of these elements without
the other resulted in no significant yield in
crease. When both P and Cu were applied to
the plant there was a highly significant increase
in yield. For example, when Cu was not added
to the fertilizer, a yield of 7.4 tons was not in
creased with the addition of P. But, where 2
pounds of Cu were added, fruit yield increased
to 28 tons with the addition of 105 pounds of P.
Where 4 pounds of Cu were supplied, the fruit
yield increased to 30.9 tons with 105 pounds of
fertilizer P. Although the similar effect of P
and Cu on the 1965 yield (Figure 1) was not
signficant the yield curves showed a trend which
was similiar to that observed in 1966.
The main
effects
Gainesville are
of
157
Cu rates
given in
on yield at
Figure 4.
When the
added Cu was increased from 0.5 to 4.0 pounds
per acre the
melons
per
yield, both
acre,
tons
increased
and
number
significantly.
of
The
average weight per melon was not affected.
At Gainesville, the combined effects of P and
Cu fertilization resulted in an interesting trend,
although these yield differences were not statis
tically significant (Figure 4). Maximum yield
with 0.5 pounds of Cu per acre was obtained
when the P rate was 70 pounds per acre. How
ever, with 4 pounds of Cu per acre the highest
yield was reached with 140 pounds of P per
acre.
The main effect of P rates on yield in the
1966 experiments at Gainesville
(Table 3)
a significant increase in yields
per
acre)
sponse
with
was
higher
not as
experiments.
rates
of
P.
great as in the
Yields
were
was
increased
This
re
Immokalee
from
7.0
tons without added P to 9.8 tons with the addi
tion of 70 pounds of P.
the
average
Discussion
(tons of melons
Number of melons and
weight of melons were
increased
The positive growth and yield response ob
tained with increased rates of P in these experi
ments
resulted because
there
was a
very
low
level of native P in the virgin flatwood soils on
which these tests were conducted.
soil
P
in
the
check
plots
The available
was
six and
eight
but not significantly.
30
25CO
UJ
X
Q
COPPER
■
>■
■
4 LB/A
*—-•
2 LB/A
▼
NO Cu
▼
iD
Z
UJ
RATE
COPPER
RATE
4 LB/A
•»-•
2 LB/A
*.•*
NO
Cu
5-
0
52
105
FERTILIZER P,
157
210
LB/A
Fig: 1.—Watermelon yields as affected by P and Cu appli
cations at Immokalee
1965.
52
105
FERTILIZER
157
P,
210
LB/A
Fig. 2.—Early vine growth as affected by P and Cu ap
plication at Immokalee. 1966.
FLORIDA
158
Table 3.
Main effects of phosphorus
on watermelon yields
P
STATE
HORTICULTURAL
P supply.
rates
- rates
HeIons
Melons
ton/A
number/A
Av.
1966
This further emphasized the need for
an adequate P supply for early plant develop
at Gainesville.
lb/A
SOCIETY,
ment, particularly, at lower temperatures which
Wt.
prevailed during the early part of these experi
lb./melon
ments.
The greatest variation in yield between
744
18.8
7.2
753
19.2
9.8
950
20.6
phate was not used.
9.3
886
20.6
could have been a location response because new
0
7.0
35
70
140
1965 and
1966 at Immokalee
land was used each year.
F values: P rade is linear** for tons of melons but not
significant for number or average weight.
pounds per acre P
able at pH 4.8)
respectively.
(ammonium acetate extract-
at Immokalee and Gainesville,
Plants which did not receive fer
tilizer P were stunted early in the season (Table
1)
and
vine-growth
received phosphate.
lagged behind
those
that
This lag period continued
was where phos
This seasonal response also
From the similar soil
test values for native soil P the location effect
was not believed to be the major factor. Possibly
the seasonal variation was a temperature effect.
In 1965 when the melon yield without added P
were almost
double
that
maximum and minimum
in
1966,
the
average
air temperatures were
6.2° and 2.4° F higher during the first six weeks
of
the
could
test.
have
The
lower temperatures
retarded
root-growth,
thus
in
1966
making
until the main vine had reached a length of
several feet. The vine-growth which occurred
the limited supply of native soil P even more
subsequently
crops other than watermelons, have reported a
was
fairly
vigorous,
but
never
equal to the growth of plants supplied with P.
This increased growth, late in the season, was
probably the results of the roots extending into
a larger volume of soil; this may indicate an
early restriction of roots subjected to a limited
critical.
Several workers
close association
P
uptake
and
(4, 8,
9), using test
between soil temperature and
their
combined
effect
on plant
growth.
The higher yields with increased rates of Cu,
both at Immokalee and Gainesville, further con
firmed the earlier studies (6, 7) reported by the
COPPER
0.5
RATE
LB/A
4.0 LB/A
0
52
105
157
0
210
FERTILIZER P, LB/A
Fig.
3.—Watermelon
yields
applications at Immokalee.
at
1966.
affected
by
35
70
FERTILIZER P,
P
and
Cu
140
LB/A
Fig. 4.—Watermelon yield as affected by P and Cu fer
tilization at Gainesville. 1966.
ORSENIGO: CELERY SEEDBED HERBICIDES
authors.
The greater response to Cu in 1966 as
compared to 1965 could not be explained on the
basis
of native soil
Cu
since
this value was
approximately the same both years.
It is possi
ble that the lower temperatures experienced in
1966 could have accentuated the Cu deficiency
by reducing root-growth, thus limiting the soil
volume from which the plant could absorb Cu.
Copper-deficiency symptoms on plants not fertlized with Cu were much more pronounced in
1966 than in 1965. In 1965 the superphosphate
contained 20 ppm Cu; therefore, when super
phosphate was added Cu was also added. This
may have been sufficient to mask Cu deficiency
in the no-Cu treatment, with a resultant higher
yield. A similar situation existed in 1966, but
the Cu content of the superphosphate was only
9 ppm; therefore, the Cu added as a contami
nant was less than in 1965.
The
effect
of Cu fertilization
on
yield
re
sponse to P fertilization is shown in Figure 3.
Both Cu and P were necessary to produce opti
mum yields on virgin flatwood soils.
tion in yield at the
two higher
The reduc
P rates, even
when 4 pounds of Cu per acre were added, sug
gested the possibility
of an antagonistic effect
of P at the highest rates.
The effect of high P
absorption on Zn, Cu and Fe uptake has been
reported (1, 2, 3) to occur under certain condi
tions on
several crops.
similar to those on which the above experiments
were
conducted,
the
P
requirement
of
approximately 105 pounds
POSTEMERGENCE
J.
Slow-growing
R.
water
P
(240
water,
space
consuming
in
and
seedlings
light.
celery
and
cannot
com
The
control
seedbeds
expensive.
can
of weeds
be
time-
Off-season and
pre-
planting cultivation and flooding programs miti
gate but not eliminate weed infestations.
Pre-
seeding soil fumigation treatments may not ef
fectively control annual weeds on the organic
ies
lFlorida Agricultural
No. 2511.
LITERATURE CITED
1. Bingham, F. T.
and micronutrients in
27:
389-391.
1963.
Relation between phosphorus
plants.
Soil Sci. Soc. Amer. Proc.
2. Bingham, F. T. and M. J. Garber.
1960. Solubility
and availability of micronutrients in relation to phosphorus
fertilization. Soil Sci. Soc. Amer. Proc. 24: 209-213.
3. Burleson, C. A., A. D. Dacus, and C. J. Gerard. 1961.
The effect of phosphorus fertilization on the zinc nutrition
of several irrigated
crops.
Soil Sci.
Soc. Amer. Proc.
25:
365-368.
4. Dadykin, V. P.
1951.
Soil temperature as one of
the factors
determining
the effectiveness
of
fertilizer.
Pachvovedenie: 557-561.
(Cited from Proc. Amer. Soc.
Hort. Sci. 75: 601-610).
5. Everett, P. H.
1961.
The effects of superphosphate
on watermelon yields. Proc. Fla. State Hort. Soc. 74: 158161.
6. Locascio, S. J., P. H. Everett, and J. G. Fiskell.
1964.
Copper as a factor
in
watermelon fertilization.
Proc. Fla. State Hort. Soc. 77: 190-194.
Locascio, S. J. and J. G. Fiskell. 1966. Copper require
ments of watermelons. Proc. Amer. Soc. Hort. Sci. 88:
Experiment Stations Journal
2Associate Horticulturist, University
glades Experiment Station, Belle Glade.
8. Locascio, S. J. and G. F. Warren. 1960. Interaction
of soil temperature and phosphorus on growth of tomatoes.
Proc. Amer. Soc. Hort. Sci. 75: 601-610.
9. Robinson, R. R., V. G. Sprague, and C. F. Gross.
1959. The relation of temperature and phosphate place
ment to growth of clover. Soil Sci. Soc. Amer. Proc. 23:
225-228.
FOR
CELERY SEEDBEDS1
soils of the Florida Everglades. Mechanical
weed control methods are not applicable to
pete effectively with annual weeds for nutrients,
essential
than where Cu was added or was adequate.
Similarly, on new land, when well-limed, P was
likely to be a limiting factor on growth and
melon yield. From the present studies, both Cu
and P were found to be major limiting factors
for melon production on flatwood soils. There
fore, the fertilization of melons on these soils
should include Cu in the fertilizer unless ade
quate Cu is known to be present in the soil or
suitable Cu sprays are employed.
HERBICIDES
Orsenigo2
celery
lbs. P2O5) per acre and the Cu above 2 pounds
per acre. With Cu deficiency, response to phos
phate fertilization was likely to be much less
568-575.
It was evident that on virgin flatwood soils,
melons was
159
of
Florida,
broadcast or drill-seeded celery seedbeds. Man
ual weed control may be costly and tedious;
some broadleaf weed species are difficult to dis
tinguish from celery seedlings during thinning,
handweeding and transplant pulling operations.
CDAA and CDEC3 are widely used for posttransplanting application (3), but these chemi
cals are not well tolerated by germinating celery
seed and young seedlings. Experience in pri-
Ser
Ever
3CDAA
is
2-chloro-N,
N-diallylacetamide.
CDEC
and
other herbicides pertinent to this report are identified in
Table
1.