The document summarizes a study that evaluated the effects of different colored plastic mulches (black, white, red, silver, and blue) with and without spunbonded row covers on the growth and yield of summer squash. The study found that mulch color and year significantly affected soil and air temperatures, with row covers increasing air temperatures. However, increased temperatures did not always result in higher yields. Colored plastic mulches with or without row covers did not increase early fruit yield of squash. The lack of effect on yield was attributed to relatively high average air temperatures that may have masked temperature treatment effects.

1. Plastic Mulches and Row Covers on Growth
and Production of Summer Squash
Garry G. Gordon
Wheeler G. Foshee, III
Stewart T. Reed
James E. Brown
Edgar Vinson
Floyd M. Woods
ABSTRACT. Row covers and colored plastic mulch are used routinely
throughout the United States to grow vegetables but are rarely used in
conjunction to produce a crop. Summer squash (Cucurhita pepo L.). cv,
Prelude 11, was grown on an Orangeburg sandy loam soil in Shorter, AL.
The summer squash was direct seeded in single rows. The experiment
consisted of 12 treatments including: (1) black plastic mulch (BPM)+spun-
bonded row cover (RC). (2) BPM alone. (3) white plastic mulch (WPM)+RC,
(4) WPM alone. (5) red plastic mulch (RPM)+RC, (6) RPM alone. (7) bare
Garry G. Gordon is affiliated with the USDA-ARS Subtropical Horticulture
Research Station, 13601 Old Cutler Road, Miami, FL 33158 (E-mail: Gary.Gordon
@ars.usda.gov).
Wheeler G. Foshee III is affiliated with the Department of Horticulture, 101
Funchess Hall. Auburn University, AL 36849.
Stewart T. Reed is affiliated with the USDA-ARS Subtropical Horticulture
Research Station, 13601 Old Cutler Road, Miami, FL 33158.
James E. Brown is affiliated with the Department of Horticulture, 101 Funchess
Hall, Auburn University, AL 36849.
Edgar L. Vinson Ill is affiliated with the Department of Horticulture, 101
Funchess Hall, Auburn University, AL 36849.
Floyd M. Woods is affiliated with the Department of Horticulture, 101 Funchess
Hall, Auburn University, AL 36849.
Address correspondence to Garry G. Gordon at the above address.
International Journal of Vegetable Science, Vol. 14(4) 2008
Available online at http://www.haworthpress.com
© 2008 by The Haworth Press. All rights reserved.
322 doi: 10.1080/19315260802215830

2. Gordon et al. 323
soil (BS)+RC, (8) BS alone, (9) silver plastic mulch (SPM)+RC. (10) SPM
alone, (II) blue plastic mulch (BLUPM)+RC, and (12) BLUPM alone.
Year and mulch color affected all variables, row cover affected plant height
and stem diameter, and the mulch color x row cover interaction affected
yield variables. Mulch color and year significantly affected air and soil
temperatures and row cover significantly affected air temperature. Soil
temperatures were more than 5°C lower than air temperatures in all treat-
ments and air temperatures were 2-5°C higher with row covers than with-
out. Increased soil and air temperatures did not always result in yield
increases. Colored plastic mulch with or without row covers did not
increase early fruit yield in squash. Lack of a mulch/row cover induced
temperature effect on yield was attributed to the relatively high mean air
temperatures that may have masked treatment temperature effects.
KEYWORDS. Cucurbita pepo, air temperature, earliness, soil temperature,
stem diameter
INTRODUCTION
The main polyethylene used in mulches is low-density polyethylene,
which is created by polymerization of ethylene under high pressure
(Lamont, 1993). The typical plastic mulch used in the United States is
1.25 mm thick and 122 to 152 cm wide and comes in rolls of 608 to
1216 m long. It is used with raised beds that are 10.2 to 15.2 cm high and
76.2 cm wide, depending on crop and cropping system (Lamont et al.,
2005). Numerous additives are incorporated into plastic to improve
specific properties of the finished product and can include antiblock
agents (a substance added to the plastic solution that acts as a barrier to
prevent adhesion of surfaces of films made from the plastic to each other
[www.patentstorm.us ]), antioxidants, pigments for color, flame retar-
dants, and photodegradable additives (Wright, 1968).
Polyethylene mulch was first noted for its ability to increase soil tem-
perature in the 1950s (Emmert, 1957). Due to the monetary value of many
horticultural crops, it is beneficial to adjust the soil's microclimate to
prolong the growing season and increase plant growth (Tarara, 2000). The
effect of plastic mulch on soil surface temperature is determined by the
optical properties of the plastic material (Ham et al., 1993). Black plastic
has intense shortwave transmittance and high shortwave absorptance,
which causes soil temperatures to be quickly raised (Dodds et al., 2003;

3. 324 INTERNATIONAL JOURNAL OF VEGETABLE SCIENCE
HeiBner et al., 2005). Beneath black plastic mulch, soil temperature may
be 10-15°F hotter than bare soil (Splittstoesser, 1990; Stevens et al.,
1991). Black mulch usually produces the hottest soil temperature
compared to other colored mulches (DIaz-Perez and Bata], 2002; Infante
et al., 1998; Jiménez et al., 2003; Lira-Saldivar et al., 2000).
Other mulch colors have been used in vegetable production. White
plastic mulch usually generates cooler soil temperatures than black plastic
(DIaz-Perez and Batal, 2002; Lamont, 1993). White plastic is preferred
during the summer growing season in warmer regions compared to black
because it can maintain soil moisture while providing cooler tempera-
tures. Use of silver plastic mulch has been reported to result in less
disease and reduce stress from silverleaf whitefly (Ber,nisia argentifolii)
and aphid (Aphididae) in certain vegetable crops (Csizinszky et al., 1995;
Lamont et al., 1990). Red plastic mulch is associated with increased yield
in tomato (Lvcopersicon esculentuin Mill.; Decoteau et al., 1989) and
other crops (Decoteau et at., 1990; Kasperbauer, 1992). It is believed that
red plastic mulch generates a positive phytochrome response. A greater
yield was found for some vegetable crops using blue plastic mulch
(Csizinszky et al., 1995).
Plastic mulch reduces the weed population in comparison to bare soil.
Plastic mulch creates a barrier against herbicide dissipation into the atmo-
sphere rendering herbicides more effective (Clarkson and Frazier, 1957;
Lourduraj et al. 1997; Rahman and Shadeque, 1999). It is this reduction in
weeds and the cost associated with their eradication that helps make the
use of plastic mulch more economical.
One of the more popular reasons for using plastic mulch is its ability to
maintain soil moisture (Orzolek and Murphy, 1993; Lamont, 1996). Drip
tape is the preferred means of irrigating vegetables when using plastic
mulch. The use of drip tape with plastic mulch allows crops to receive
adequate moisture and is more cost efficient than overhead irrigation
(Berthelot and Robertson, 1990; Cooley et at., 2007). Studies have
concluded that soil beneath plastic mulch and drip tape will have higher
soil moisture than bare soil with drip tape (Alam and Zimmerman, 2001;
Gough, 2001; Infante et al., 1998). Liakatas et at. (1986) documented the
ability of plastic mulches to alter the plant's microenvironment due in part
to its ability to restrict soil water evaporation. Other advantages due to use
of colored plastic mulches include improved fruit quality (Brown and
Channel l-Butcher, 2001; Lamont, 1996), increased yield (Baker et at.,
1999; Brown et at., 1995; Farias-Larios et at., 1999; Lamont et al., 2005;
May et al., 2005), reduced fertilizer leaching (Alain and Zimmerman,

4. Gordon etal. 325
2006; Clarkson, 1960), and reduced soil compaction (Gough, 2001;
Lamont, 1996).
Row covers act to protect seedlings from frost, heavy rains, periods of
dry weather, and cool winds without blocking needed moisture and
sunlight (Jensen, 2000). Row covers are used to increase temperature
and promote earlier yield. Spunbonded polyester row covers were intro-
duced in the early 1980s. Spunbonded polyester row covers are made
from a thin mesh of white synthetic fibers. Heat is retained, but water can
penetrate the row cover, allowing for overhead irrigation, or rain, to
hydrate plants and help to prevent soil compaction. The weight of polyes-
ter row covers can range from 10 to 67+ g/m 2 (Penn State, 2003). Spun-
bonded row covers in the 14.2 to 35.5 grange render a 1.1°C protection
against frost in the spring and even greater frost protection in the fall
(Penn State, 2003).
Phytochrome is the photoreceptor responsible for light-regulated
growth responses. Research has documented a phytochrome response to
colored plastic mulch. Longer leaves and higher shoot/root ratios were
found in turnip plants grown on blue and green mulches that reflected
higher Far Red:Red (FR:R) ratios than on white plastic mulches that gen-
erated lower FR:R ratios (Antonious et al., 1996). These researchers
believed the higher yields were due to the red plastic mulch's superior
ability to produce a greater FR:R ratio compared to black plastic mulch.
Blue light treatments have been shown to effect morphological, meta-
bolic, and directional reactions in plants (Senger and Schmidt, 1994). Hart
(1988) reported that blue light activates stomatal opening by promoting K
uptake and water movement into the plant's guard cells. Kadaman-Zahavi
and Ephrat (1976) found that blue light would reduce stem elongation.
Hatt et al. (1993) and Kasperbauer and Loughrin (2004) found that white
plastic mulch reflected more blue light than other mulch colors used in
their experiments. Antonious et al. (1996) reported that white plastic
mulch reflected the largest amounts of blue light. However, turnips grown
on white plastic mulch had the least flavor among turnips grown on other
mulch colors. Decoteau et al. (1988) believed that shorter stems and more
auxiliary growth could result from the blue light reflected by white plastic
mulch to tomato plants.
There is little known on how colored mulch and row covers affect
summer squash (Cucurbita pepo L.). This project was undertaken to
evaluate growth and yield, including earliness of yield, of summer
squash produced on different colored plastic mulch, with or without a
row cover.

5. 326 INTERNA TIONAL JOURNAL OF VEGETABLE SCIENCE
MATERIALS AND METHODS
The research was conducted at the E. V. Smith Research Experiment
Station in Shorter, Alabama. The soil type is an Orangeburg sandy loam,
fine-loamy siliceous thermic Typic Kandiudult. A soil pH of 7 was
recorded in 2003 and 6.1 in 2004. The summer squash, cv. Prelude II,
was used.
Pre-plant fertilizers were applied in 2003 and 2004 in accordance with
the soil test recommendations from Auburn University Soil Testing Lab
(Auburn, Ala.). Phosphorous was applied at the rate of 0.03 kgha 1 in
2003 and 0.04 kg-ha-1 in 2004 (Table I). Potassium was applied at the rate
of 0.08 k--ha-1 in both 2003 and 2004. The plots received 0.06 and
TABLE 1. Fertilizer and other chemical
amendments applied to squash plots in
2003 and 2004
Year
2003 2004
Preptant (kg.ha1)
Ammendment
Phosphorus 0.03 0.04
Potassium 0.08 0.08
Magnesium 0.02 0.02
Calcium 1.09 0.23
Ammonium nitrate 197 209
Chloropicrin 336 336
In season (kg.ha 1)
20-20-20
29.2
61.6
Ca(NO3)2
20.5
z
Seven
1.4
Endosulfan
2.24
z
(L.ha1)
Curbit (L.ha1)
4.67
4.67
Round-up
2.34
4.67
Asana
0.70
2.82
Manex
3.73
15.00
Ambush
0.88
z
Bravo
100.76
2.34
Topsin
0.58
z
Asana
0.70
z
Z_not applied.

6. Gordon etal. 327
0.02 kgha of Mg in 2003 and 2004, respectively. Liquid calcium
was applied through drip irrigation at a rate of 1.09 kg-ha' in 2003
and 0.23 kg.ha7 l in 2004. No time was added to plots in either year.
In 2003 and 2004 ammonium nitrate (34-0-0) was applied at 197 and
209.44 kg-ha-1 , respectively. Prior to laying plastic mulch, Pic Brom 33®
(Soil Chemicals Corporation, Hollister, Calif.; 67% CH 313r, 33% Chlorop-
icrin (trichloro(nitro)methafle)) was applied at a rate of 336 kgha on 17
April 2003 and on 27 March 2004, respectively. Fertilizers and pesticides
were also applied to developing plants (Table 1). Nitrogen, P, and K (20-
20-20) were applied to the soil through drip fertigation tubes at the rate of
29.2 kg-ha-1 (5.8, 2.6, and 4,8 kg of N-P-K) once a week from 30 May to
8 July 2003. During 2004, 61.6 kg-ha of 20-20-20 was injected into the
soil once a week from 11 May to 25 June 2004. Liquid calcium nitrate,
20.5 kg.ha', was applied to the soil through fertigation into the soil from
6 June to 28 June 2003.
Pesticides were applied once a week according to label directions in
May 2003 and 2004. Curbit® herbicide (Loveland Products Inc., Greeley,
Cob.;
benzenamine) was applied for weed control at a rate of 4.67 Lha1.
Round_Up® herbicide (Monsanto Company, St. Louis, Mo.; isopropy-
lamine salt of glyphosate) was applied between rows at 2.34 L'ha and
4.67 Lha' in May 2003 and 2004, respectively. Asana XL® (DuPont
Corporation, Wilmington, Del.; (S)-cyano (3-phenoxyphenyl) methyl (S)-
4chloroalpha(1-methylethyl) benzene acetate) was applied at 0.70 and
2.82 Lha in May 2003 and 2004, respectively, to control stink bugs
(Halyornorpha halys) and squash hugs (Anasa tristis). Manex® (DuPont
Corporation; Mn ethylenebisdithiocarbamate) was applied at 3.73 and
15 L.W1 in 2003 and 2004, respectively, to control diseases. In June of
2003, a total of 0.88 Lha7
1 of Ambush®(Syngenta Crop Protection
Pty Limited, North Ryde, NSW; 3Phenoxyphenyl)rnethyl(±)2,2
dimethylcyclopropane-carbOXYlate) and 2.24 kg.ha (50 wp) of Endosulfan®
(Bayer CropScience AG., Monheim am Rhein, Germany; 6,7,8,9, 10,10-
hexachioro- I ,5 ,5a,6,9,9a-hexahydro-6, 9methano-2,4,3-beflZodiOXathie
pine-3-oxide) were applied to plots for use as insecticides. In June of
2003, three separate applications of 2.92 Lha of Bravo WS® (DuPont
Corporation; tetrachloroisophthalOnitrile) and 0.58 L-ha7
i of Topsin M®
(ATOHNA Chemicals Inc., King of Prussia, Pa.; dimethyl [(1,2-phenylene)
bis-( iminocarbonothioyl)]bis[carbamatel) were applied to plots. On
2 July 2003, 92 L-ha l Bravo WS and 0.70 L•ha 1 of Asana XL were
applied as a fungicide and insecticide, respectively. In 2004, Sevin80S0

7. 328 INTERNATIONAL JOURNAL OF VEGETABLE SCIENCE
(Bayer CropScience AG., Monheim am Rhein, Germany; carbaryl
(1 -naphthyl N-methylcarbamate) was applied on plots at a rate of 1.4 kg-
ha-along with Bravo WS® 2.34 Lha'.
Plastic drip irrigation lines (Toro Ag, El Cajon, Calif.), 10 mm thick,
emitters spaced at 30.48 cm covered by six 111-rn-long strips of black
plastic were applied simultaneously over beds with a plastic mulch layer
machine (Kenco Manufacturing Inc., Ruskin, Fla.). Seed were sown on
8 May 2003 and 20 April 2004 into raised beds (15.24 cm in height)
through holes created by the plastic mulch layer machine. Squash seeds
were planted 30.48 cm apart within each row. Plots 6.08 x 1.52 m (L x W)
were arranged in a randomized complete block design. Beds were 9.84 m
apart.
The experiment consisted of twelve treatments: (1) black plastic mulch
(BPM)+spunbonded row cover (RC), (2) BPM alone, (3) white plastic
mulch (WPM)+RC, (4) WPM alone, (5) red plastic mulch (RPM)+RC,
(6) RPM alone, (7) bare soil (BS)+RC, (8) BS alone, (9) silver plastic
mulch (SPM)+RC, (10) SPM alone, (11) blue plastic mulch (BLIJPM)+RC,
and (12) BLUPM alone. Sections of black plastic (6.08 x 0.91 m) were
removed and replaced with silver, white, blue, and red pieces of plastic. The
original black plastic was retained in place for treatments requiring black
plastic mulch. For the control treatment, a black plastic section was not
replaced leaving exposed the bare soil. The silver, red, white, and black
plastic (Ken-Bar Inc., Reading, Mass.) was 1.5 mm thick and 91.44 cm
wide. The blue plastic mulch (Pliant Corp., Schamburg, Ill.) and was
1.25 mm thick and 152 cm wide.
Row covers, 170.18 cm wide, were established on 20 May 2003 and
26 April 2004. Edges of row cover strips were tucked into the soil around
the edges of each plot and left to float loosely in an effort not to hinder
plant growth as well as to prevent the loss of captured heat. Row covers
were removed from plots on 3 June 2003 and 24 May 2004, respectively.
Soil temperature was measured with a soil probe thermometer
(Taylor® Switchable Digital Thermometer, Taylor Precision Products
LP, Oak Brook, Ill.) from a depth of 10.16cm in each plot. Air temper-
ature was recorded with an indoor/outdoor thermometer (Taylor
Precision Products LP) with sensors attached to the heat conducting
wire (Toro Ag, Bloomington, Minn.) placed in the center of each plot
at 12.7 cm above ground level. Soil and air temperatures were recorded
from 27 May to 3 June 2003 and 20 to 27 May 2004, a time span long
enough to demonstrate temperatures that occurred under the various
treatments.

8. Gordon et al. 329
Stem diameters were measured with a 500-196 caliper (Mitutoyo
Digimatic Corp., Sakato Takatu-ku, Kawasaki-shi, Kanagawa 213, Japan)
5 cm above ground level around bases of plants on 4 June 2003 and
28 May 2004. Height measurements were taken with a meter stick by
measuring from the base of the plant to the tip of the highest leaf. Plant
heights and stem diameters were taken on the day row covers were
removed. Squash fruit were considered either marketable or cull based on
size, shape, color, and presence of insect or disease damage in accordance
to the guidelines of the E.V. Smith Research Center.
Squash was harvested from 9 June to 14 July in 2003 and from
25 May to 2 July in 2004. Harvest occurred every other day with week-
ends being the exception. Yield differences among treatments were
determined by weighing marketable and cull fruit at each harvest. Fruit
collected from 5 through 27 June 2003 and 25 May through 14 June
2004 were considered early yield. All data were analyzed using SAS
(SAS, 2003, ver. 9.1, Cary, NC.). Effects of mulch color, row cover,
and year on selected plant physical characteristics and yield compo-
nents were tested by ANOVA. If an interaction was present it was used
to explain results. For main effects, where appropriate, mean separation
was with the Fisher's least significant difference test. Temperature data
were analyzed using the GLM repeated measures procedure. Air and
soil temperatures were reported as means for values measured over the
recording period during each year. Pearson correlation coefficients
were determined for air and soil temperatures versus total yield. Mean
separation for plant height, weight, and stem diameter was accom-
plished using the Fisher's least significant difference test. Yield compo-
nents, with mulch color x row cover interaction, were subjected to least
squares analysis.
RESULTS
Year and mulch color affected all variables, row cover affected plant
height and stem diameter, and the mulch color x row cover interaction
affected yield variables (Table 2). The presence of a row cover had a
significant effect on stem diameter and plant height. Squash stem diam-
eter, plant height, and fresh weight are shown in Table 3. Plants were
significantly taller in 2004 than 2003. Treatments consisting of mulch
plus row cover produced significantly taller plants than treatments with-
out a row cover. Plants grown on BS were shorter than those grown

9. U -0
c::U)
C
CU
C-D
ca
(U
CUD
ci)
>E
. •
I) (I) >
>
s—CU
co
o ca
0U)
-C
0 Cd)
E C >
U)
0C co
U) (U
cD
O CU
-CC
- 0
(o .2 c
- Co
(UCU
> -
zo
<0
uJ--
-ix
<2I-0
0
ci)
=
Cci 00iflCj
o0)o
> 00000
0
•5o D - 0) ,- 0)
-- Q0)0C
•6 >• coocF- 00000
II)
-Q
!
mci) 00)00r.-
. 000,-
- d0000
0
I-
5OD
00)CO,-0
00QC)
OLUQ
W c000o
ci)
0
(ci
ci)
•-DC'J
Cci 0(000(D
E> 0C'J00CJ
CcJ 00) 0
- ddddd
Cci
Lid
E ON- ON- CD
-E oc'jooj -i-
(/ OOQL(
D 00000
C) 2
fl- LO
LO co 00)0)
OC')OODO)
- 000)0
000do
C) z
•a5 .-.-,-0cJ
r 000çc.i)
0000)0)
C QOOCC
. 00000
0
ci)
>
- ;- 0
C C)
(1) O 0 ><
c 0 -
cci
330

10. Gordon et al.
33'
TABLE 3. Mian effects of year, mulch color and row cover
on squash plant height, fresh weight and stem diameter
Source Plant Stem
Year
2003
2004
Mulch color
Bare soil
Black
Blue
Red
Silver
White
Row cover
None
Yes
Height (cm) Fresh
weight (kg)
29.8 by 0.12 b 20.0 a
72.5 a 0.79 a 17.8 b
33.7 b
0.17 b
27.2 b
46.5 a
0.46 a
29.3 a
47.6 a
0.51 a
29.5 a
44.9 a
0.47 a
28.8 ab
43.9 a
0.53 a
29.8 a
44.9 a
0.50 a
29.4 a
37.9 b
0.44 a
30.0 a
49.3 a
0.45 a
28.1 b
values within columns followed by the same letter are not significantly
different, P 0.05, Fisher's Least Significant Difference test.
diameter (mm)
under any of the plastic mulch treatments. Greater fresh weights
occurred in 2004 than 2003. In addition, plants grown in BS and BS+RC
treatments consistently produced among the lowest squash fresh
weights. Stem diameters were smaller in 2004 than 2003 and smaller
with row cover than without. Bare soil produced the smallest stem diam-
eters with the BS+RC treatment producing smaller diameters than BS
without cover.
Early marketable and cull yields were lowest from plants grown on
bare soil plus a row cover followed by bare soil alone (Table 4). In fact,
early marketable yields from bare soil regardless of whether a row cover
was present or not were significantly lower than all but the black mulch
without a row cover treatment. The highest early yield, marketable plus
cull combined were from black mulch plus a row cover followed by blue
mulch without a row cover. Early yields were between 59% and 65% of
overall yields. Total yield followed the same trend as early yield, bare soil
with row cover, and bare soil without cover produced the lowest yields.
Black mulch with a row cover and blue mulch without a row cover

11. 332 INTERNATIONAL JOURNAL OF VEGETABLE SCIENCE
TABLE 4. Interaction effects of mulch color and row cover on early
and total marketable, cull and overall yield for summer squash
Source
Early yield
Total yield
Marketable Cull Marketable Cull Overall
(kg/plot) (kg/plot) (kg/plot) (kg/plot) (kg/plot)
Row cover x mulch
Bare soil
Blue
Black
Red
Silver
White
Bare soil
Blue
Black
Red
Silver
White
3.7 dX
10.0 ab
11.9 a
9.1 b
8.6 bc
9.9 ab
6.5 c
12.1 a
8.5 bc
9.8 ab
10.0 ab
10.2 ab
13.4 a
4.9 b
3.0 e
9.8 abc
11.1 a
9.4 abc
6.9 cd
9.0 abc
5.3 de
9.9 ab
7.4 bcd
7.3 bcd
8.7 abc
8.0 bcd
8.9 a
7.1 b
6.0 d
14.1 ab
17.9 a
13.2 b
12.8 bc
14.2 ab
9.0 cd
17.3 a
12.8 bc
14.3 ab
14.2 ab
14.6 ab
17.5 a
9.2 b
5.3 d
16.1 ab
19.4 a
16.Oab
13.4 bc
16.3 ab
9.7 Cd
16.9 ab
13.2 bc
14.4 b
14.7 b
15.0 b
18.3 a
10.2 b
11.3 e
30.2 abc
37.3 a
29.2 bc
26.3 Cd
30.5 abc
18.7 de
34.2 ab
26.0 cd
28.7 bc
29.0 bc
29.5 abc
35.8 a
19.4 b
Cover
None
Year
2003
2004
'Mean separation within each column was determined by Least Squares Analysis. Values
followed by the same letter are not significantly different at P!^ 0.05.
produced the highest overall yields. By the end of harvest the percent of
total yield separated as cull increased over that found in early yield. Year
had a significant effect on marketable yield (Table 2). Total yield in each
mulch/row cover treatment was lower in 2004 than 2003. This is likely
due to air temperatures in excess of 37°C for portions of the 2004 growing
season.
Mulch color and year significantly affected air and soil temperatures
and row cover significantly affected air temperature (Table 5). Air and
soil temperatures were higher in 2004 than 2003 (Table 6). Air tempera-
tures as affected by mulch color followed the order: Silver ^! Blue ^! White
= Red = Black = Bare soil. Soil temperatures as affected by mulch color
followed the order: Blue ^! Black ^! Red > White = Bare soil > Silver.
Plots with row covers had significantly higher air temperatures than plots
without row covers in 2003. Row cover did not affect soil temperature.
There was no correlation between air or soil temperature and total yield
(Table 5).

12. Gordon et al.
333
TABLE 5. ANOVA results for the effects
of treatments on air and soil temperature
and Pearson Correlation Coefficient for
temperature verses yield
Treatment Air temperature Soil temperature
Mulch color 0.0063** 0.0001"
Row cover 0.0001 0.4311
Year 0.0001*** 0.0001***
Rep
O,326ns 0.1913ns
Mulch x Cover 0334r 0.3227°
r for Yield
049*** _0.31**
***significant at the 0.05 probability level.
snot significant at the 0.05 probability level.
TABLE 6. Main effects of year, mulch
color and row cover on summer squash
mean air and soil temperatures
Source
Year
2003
2004
Mulch cover
Bare soil
Black
Blue
Red
Silver
White
Row cover
None
Yes
Temperature (°C)
Air Soil
35.5 by 27.3 b
39.0 a 29.3 a
36.6 b 27.3 c
36.6 b 29.3 ab
37.7ab 29.6a
37.0 b 28.9 b
38.6 a 26.6 d
37.3 b 27.8 c
35.8 b 28.2 a
38.8 a 28.3 a
'values within columns followed by the same
letter are not significantly different, P !^ 0.05,
Fisher's Least Significant Difference test.

13. 334 INTERNATIONAL JOURNAL OF VEGETABLE SCIENCE
DISCUSSION
Plants grown on BS with or without a row cover were smaller in
height, fresh weight, and stem diameter than those grown under any of the
plastic mulch treatments. This is consistent with findings in other studies.
For example, Brown et al. (1993) and Lopez (1998) found that squash
was taller with use of row covers plus plastic mulch than without row
covers. Brown et al. also reported that bare soil resulted in a lower plant
fresh weight than plastic mulch treatments. Row covers create an
enclosed microenvironment for plants. The enclosed environment brought
plants close together and sometimes enabled individual plants to make
contact. Kasperbaur (1971, 1987) found the amount of far-red light
reflected from neighboring plants increased at higher planting densities
affecting assimilate partitioning. As a result, plants in dense populations
were taller than those at lower densities. The colored plastic mulches used
in our study may have contributed to the FR light reflected to the squash
plants. A higher FR:R ratio due to light reflectance from the plastic mulch
may have activated the plants' phytochrome responses, signaling plants to
compete in an attempt to grow taller than their neighbors under the row
cover (Franklin and Whitelani, 2006). Competition between plants could
explain why squash plants grown with plastic mulch and row covers were
taller than those grown with plastic mulch alone or on bare soil (Wilkinson
et. al., 1981). Studies with a spectroradio meter can measure the light spec-
trum reflected from colored mulches. Further research is needed to
confirm possible benefits of colored mulch and row covers for production
of squash.
Air temperatures in plots with row covers were consistently higher
than in plots without row covers. Others researchers have reported higher
air temperatures with use of plastic mulch plus row cover compared to
plastic mulch alone or bare soil (Loy and Wells, 1975; Moreno et al.,
2002; Rubeiz and Freiwat, 1999). In our study there was no correlation
between air or soil temperature and total yield. The lack of a mulch/row
cover induced temperature effect on yield may be due to the relatively
high mean air temperatures during this study. Wien et al. (2004) found
delayed fruiting in certain pumpkin (Cucurbita sp.) cultivars at 28°C.
In our study, mean air temperatures were above 33°C in every plot. This
may have confounded temperature effects on yield. Plastic mulches could
have a positive effect on growth and yield of vegetable crops as reported
by Decoteau et al. (1989) and Hatt et al. (1993) under more moderate
temperatures.

14. Gordon etal. 335
With increased earliness in squash fruit development, growers can
possibly generate greater revenue if a marketing opportunity exists.
Brown et al. (1993) reported earlier squash yield with row cover plus
plastic mulch compared to bare soil. Dickerson et al. (2003) found earlier
yields under plastic mulch with or without row cover compared to bare
soil. In our study, early yields were higher in mulched plots than on bare
soil; however, there were no differences between bare soil and mulched
plots in the percentage of total yield produced early. High temperatures
during the growing season likely masked effects of mulch colors on
squash yield.
The bare soil with a row cover and hare soil alone had the lowest total
marketable yields. This is consistent with others who found that use of
plastic mulch with or without row covers generates greater squash yields
than that grown on bare soil (Bryan, 1966; Dickerson et al., 2003;
Orzolek and Murphy, 1993; Orzolek et al., 2003). Total cull squash yield
was similar to marketable yields.
LITERATURE CITED
Alam. M. and R. Zimmerman. 2001. Subsurface drip irrigation and plastic mulch effects
on yield and brix levels of Kahocha squash. Cucurbita moschata. Dept. Biol. Agric.
Eng., Kansas State Univ., Manhattan. Kan. (http://www.oznet.ksU.edU/SWaO/Irngationt
Kahocha%20Study%20repOrt%2OLateSt.Pdf).
Antonious, G.F., M.J. Kasperbauer, and M.E. Byers. 1996. Light reflected from colored
mulches to growing turnip leaves affects glucosinolate and sugar contents of edible
roots. Phytochem. Photohiol. 64(3):605-610.
Baker, L.B.B.. J.C. Henning, S. Jenni, E. Flava. and K.A. Stewart. 1999. An economic and
energy analysis of the number of pepper production systems using a range of nitrogen
levels plastic mulch and irrigation. Proc. Natl. Agr. Plast. Congr. 28:82-87.
Berthelot. P.B. and C.A. Robertson. 1990. A comparative study of the financial and
economic viability of drip and overhead irrigation of sugarcane in Mauritius. Agric.
Water Mgt. 17:307-315.
Brown, i.E., R.P.Yates, M.S. West, and C. Stevens. 1993. Effects of planting methods and
row cover on summer squash production. Proc. Natl. Agr. Plast. Congr. 24:270-273.
Brown, J.E. and C. Channell-Butcher. 2001. Black plastic mulch and drip irrigation affect
growth and performance of bell pepper. J. Veg. Crop Prod. 7(2):109-112.
Brown, J.E., S.P. Kovach, W.D. Goff, D.G. Himelrick, K.M. Tilt, W.S. Gazaway,
L.M. Curtis, and T.W. Tyson. 1995. Fumigation and mulch affect yield, weight, and
quality of 'Pimiento' pepper Capsicum nnnuuni L. J. Veg. Crop Prod. 1(2):71-80.
Bryan. H.H. 1966. Effect of plastic mulch on the yield of several vegetable crops in north
Florida. Fla. Agric, Expi. Sta. J. 2532:139-146.

15. 336 INTERNATIONAL JOURNAL OF VEGETABLE SCIENCE
Clarkson, V.A. 1960. Effect of black polyethylene mulch on soil microclimate tempera-
ture and nitrate level. Agron. J. 52(6):307-309.
Clarkson, V.A. and W.A. Frazier. 1957. Effect of paper and polyethylene mulches and
plastic caps on cantaloupe yields and earliness. J. Amer. Soc. Hort. Sci. 69:400-404.
Cooley, E.T., B.L. Lowery, K.A. Kelling. and S. Wilner. 2007. Water dynamics in drip
and overhead sprinkler irrigated potato hills and development of dry zones. Hydrol.
Proc. 21:2390-2399.
Csizinszky. A.A., D.J. Schuster. and J.B. King. 1995. Color mulches influence yield and
pest populations in tomatoes. J. Amer. Soc. Hort. Sci. 120:778-784.
Decoteau, DR., M.J. Kasperhauer, D.D. Daniels. and P.G. Hunt. 1988. Plastic mulch
color effects on reflected light and tomato plant growth. Sci. 1-lortic. 34:169-175.
Decoteau. DR., M.J. Kasperhauer. and P.G. Hunt. 1989. Mulch surface color affects yield
of fresh-market tomatoes. J. Amer. Soc. Hort. Sci. 114(2):216-219.
Decoteau, DR.. M.J. Kasperhauer. and P.G. Hunt. 1990. Bell pepper plant development
over mulches of diverse colors. Hortsciencc 25(4):460-462.
Diaz-Perez. J.C. and D. Batal. 2002. Colored plastic film mulches affect tomato growth
and yield via changes in root-zone temperature. J. Amer. Soc. Hort. Sci. 127(1):
127-136.
Dickerson, G., S. Guldan, L.M. English. and P. Torres. 2003. Effects of woven, black
plastic mulch and row cover on winter squash and pepper production. Proc. Natl. Agr.
Plast. Congr. 31:63-67.
Dodds, G.T., C.A. Madramootoo, D. Janik, E. Fava, and A. Stewart. 2003. Factors
affecting soil temperatures under plastic mulches. Trop. Agric. (Trinidad) 80:6-13.
Emmert, E.M. 1957. Black polyethylene for mulching vegetables. Proc. Amer. Soc. Hurt.
Sci. 69:464-469.
Farias-Larios, J., J.G. López-Auguirre. M. Orozco-Santos. C. Guerrero. and C. Sandoval.
1999. Polyethylene and organic mulch for honey dew melon production in western
Mexico. Proc. NatI. Agr. Plast. Congr. 28:128-133.
Franklin. K.A. and Whitelam. G.C. 2006. Improvement of horticultural and ornamental
crops through transgellic manipulation of the phytochrome family of plant photorecep-
tors. J. Crop Improvement. 17(1-2):263-278.
Gough, R.E. 2001. Color of plastic mulch affects lateral root development but not root
system architecture in pepper. Hortscience 36(1):66-68.
Ham. J.M., G.J. Kluitenherg. and W.J. Lamont. 1993. Optical properties of plastic
mulches affect the held temperature regime. J. Amer. .Soc. Hort.Sci. 118(2):188-193.
Hart, J.W. 1988. Light and plant growth. Unwin Hyman, London.
Hatt, HA.. M.J. McMahon. D.E. Linvill, and D.R. l)ecoteau. 1993. Influence of spectral
qualities and resulting soil temperatures of mulch films on bell pepper growth and
production. Proc. NatI. Agr. Plast. Congr. 24:233-238.
Hei6ner. A., S. Schmidt. and B. Von Eisner. 2005. Comparison of plastic mulch films with
different optical properties for soil covering in horticulture: Test under simulated
environmental conditions. J. Sci. Food Agr. 85:539-548.
Infante, ML., S.A. Garrison, and S.A. Johnson. 1998. Influence of black plastic mulch,
bare ground, and no-till systems on yield of summer squash. Proc. NatI. Agr. Plast.
Congr. 27:178.

16. Gordon etal. 337
Jensen, M.H. 2000. Plasticulture in the global community-View of the past and future.
Proc. Natl. Agr. Plast. Congr. 29: Appendix A: 1-10.
Jimdnez. L.L. M.R. Quezada. J. Mungufa. and B. Cedcno. 2003. Effect of color plastic mulch
on photosynthesis. growth and yield of potato. Proc. Nail. Agr. Ptast. Congr. 31:95-99.
Kadaman-Zahavi. A. and E. Ephrat. 1976. Development of plants in filtered sunlight II.
Effects of spectral composition, light intensity, day length. red and far-red irradiations
and long and short day grasses. Israel J. Bot. 25:11-23.
Kasperhauer. M.J. 1992. Phytochrome regulation of morphogenesis in green plants: from
Beltsville spectrograph to colored mulch in the field. Photochem. Phytohiol.
56(5):823-832.
Kasperhauer, M.J. 1971. Spectral distribution of light in a tobacco canopy and effects of
end-of-day light quality on growth and development. Plant Physiol. 47:775-778.
Kasperhauer. M.J. 1987. Far-red light reflection from green leaves and effects on
phytochrome-mediated assimilate partitioning under field conditions. Plant Physiol.
85:350-354.
Kasperhauer. M.J. and J.H. Loughrin. 2004. Butterhean seed yield, color and protein
content are affected by photomorphogenesis. Crop Sci. 44:2123-2126.
Lamont. W.J. 1993. Plastic mulch for the production of vegetable crops. HortTechnology
3:35-39.
Lamont, W.J. 1996. What are the components of a Plasticulture vegetable system? Hort-
Technology 6(3):150-154.
Lamont. W.J., M.D. Orzolek. and B. Dye. 2005. Production of early specialty potatoes
using Plasticulture. Proc. Nat]. Agr. Plast. Congr. 32:7-10.
Lamont. Wi., K.A. Sorensen, and C.W. Averre. 1990. Painting aluminum strips on black
plastic mulch reduces mosaic symptoms on summer squash. Hortscience 25:1305.
Liakatas, A., J.A. Clark, and J.L. Monteith. 1986. Measurements of heat balance under
plastic mulches. Agric. Forest Meteorol .36.227-239.
Lira-Saldivar. RH., R. Quezada. and J. MuoguIa. 2000. Soil temperature under different
photodegradable plastic mulches and its relationship with earliness and yield of
cantaloupe. Proc. Nail. Agr. Plast. Congr. 29:315-320.
Lopez. M.V. 1998. Growth, yield and leaf NPK concentrations in crop-covered squash.
J. Sustain. Agr. 12(4):25-38.
Lourduraj. C., A.K. Padmini. R. Rajendran, V. Ravi, T. Pandiarajan. and V.V. Sreenarayanan.
1997. Effect of plastic mulching on hhendi Abelinoschus esculenius (L.) Moench.
South Indian Hurt. 45(3&4): 128-133.
Loy. J.B. and O.S. Wells. 1975. Response of hybrid muskmelons to polyethylene row cov-
ers and black polyethylene mulch. Sci. Hortic. 3(3):223-230.
May, D., B. Hanson. and R. Molinar. 2005. Plastic color and composition effect on
earliness, yield. and quality of cantaloupe and bell pepper in central California. Proc.
Natl. Agr. Plast. Congr. 32:136-141.
Moreno, D.A., G. Vullora. J. Heniández, N. Castilla. and L.R. Monreal, 2002. Yield and
chemical composition of Chinese cabbage in relation to thermal regime as influenced
by row covers. I. Amer. Soc. Hort. Sci. 127(3):343-348.
Orzolck. M.D. and J.H. Murphy. 1993. The effect of colored polyethylene mulch on yield
of squash and pepper. Proc. Natl. Agr. Plast. Congr. 24:157-161.

17. 338 INTERNATIONAL JOURNAL OF VEGETABLE SCIENCE
Orzolek, M.D., J. Murphy. and J. Ciardi. 2003. The effect of colored polyethylene mulch
on the yield of squash, tomato and cauliflower. Penn State Center for Plasticulture.
31 January 2006. (http://plasticulture.cas. psu.edul cmulch-93.1-itm).
Patentstorm. 2007. U.S. patent 5491013-Static-dissipating adhesive. (http://www.patentstomi .
us/patetits/5491013-description.htm]).
Penn State. 2003. Row Covers. (http://www.pliisticulture-cas.psu.edLi/RowCovel-S.Iltil)l).
N. and A. Shadeque. 1999. Comparative efficacy of mulches with or without a
herbicide on growth and yield of lady's finger [Abelmoschus esculentus (L.) Moench
(var. Vijaya)]. J. Agr.Sci. Soc. NE India, 12(1):123-127.
Ruheiz, I.G. and M.M. Freiwat. 1999. Row cover application duration effects on field and
long shelf-life tomato in a dry temperature climate. Proc. Natl. Agr. Plast. Congr. 28:
100-104.
Senger. H. and W. Schmidt. 1994. Diversity of photoreceptors. p. 301-324. In: R.E. Kendrick
and G.H.M. Kronenherg (eds.). Photomorphogenesis in plants. Kluwer Academic
Publishers. Dordrecht.
Splittstoesser. W.E. 1990. Vegetable growing handbook. 3rd ed. Van Norstrand
Reinhold, New York.
SAS. 2003. Statistical Analysis System. Version 9.1. SAS Institute Inc., Cary, N.C.
Stevens. C., V.A. Khan, J.E. Brown. G.J. Hochmuth, W.E. Splittstoesser, and
D.M. Granberry. 1991. Plastic chemistry and technology as related to plasticulture and
solar heating of soil. p. 141-158. In: J. Katan and J.E. Devey (eds.). Soil solarization.
CRC Press, Boca Raton, Fla.
Tarara, J.M. 2000. Microclimate modification with plastic mulch. HortScience. 35(2):
169-180.
Wien. H.C., S.C. Stapleton, D.N. Maynard. C. McClurg. and D. Riggs. 2004. Flowering,
sex expression, and fruiting of pumpkin (Cucurbita sp.) cuttivars under various
temperatures in greenhouse and distant field trials. HortScience 39:239-242.
Wilkinson. RE.. M.J. Kasperhauer. and C.T. Young. 1981. Free amino acid content of
burley tobacco leaves developed under different light and temperature conditions.
J. Agric. Food Chem. 29:658-660.
Wright. J.C. 1968. Production of polyethylene film. Proc. Natl. Agr. Plast. Congr. 8:72-79.