EPA-600/3-77-128
November 1977
Ecological Research Series
THE EFFECTS OF OXIDANT AIR POLLUTANTS
ON SOYBEANS, SNAP BEANS AND POTATOES
ironmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Corvallis, Oregon 97330
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EPA-600/3-77-128
November 1977
THE EFFECTS OF OXIDANT AIR POLLUTANTS
ON SOYBEANS, SNAP BEANS AND POTATOES
by
H. E. Heggestad, R. K. Howell and J. H. Bennett
Plant Stress Laboratory
Plant Physiology Institute
Northeastern Region
Agricultural Research Service
U. S. Department of Agriculture
Beltsville, Maryland 20705
ARS No. 12-14-1001-185
Project Officer
L. C. Raniere
Terrestrial Ecology Branch
Corvallis Environmental Research Laboratory
Corvallis, Oregon 97330
This study was conducted
in cooperation with
U.S. Department of Agriculture
Beltsville, Maryland 20705
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OREGON 97330
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DISCLAIMER
This report has been reviewed by the Corvallis Environmental
Research Laboratory, U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the con-
tents necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of trade names
or commercial products constitute endorsement or recommendation for
use by either EPA or USDA.
ii
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FOREWORD
Effective regulatory and enforcement actions by the Environmental Protection
Agency would be virtually impossible without sound scientific data on pollu-
tants and their impact on environmental stability and human health. Respon-
sibility for building this data base has been assigned to EPA's Office of
Research and Development and its 15 major field installations, one of which
is the Corvallis Environmental Research Laboratory (CERL).
The primary mission of the Corvallis Laboratory is research on the effects
of environmental pollutants on terrestrial, freshwater, and marine ecosystems;
the behavior, effects and control of pollutants in lake systems; and the de-
velopment of predictive models on the movement of pollutants in the biosphere.
This report summarizes the results of five years of research related to the
effects of photochemical oxidants on soybeans, snap beans and potatoes. The
work supports CERL's mission in strengthening the scientific bases for
secondary air quality standards required by the Federal Clean Air Act.
A. F. Bartsch
Director, CERL
iii
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PREFACE
Air pollution research is conducted in the Plant Stress
Laboratory to determine the effects of air pollutants on plants and
to develop improved technology for minimizing and preventing damage
by the use of genetic, chemical, mechanical and other methods. Both
basic and mission-oriented research are required to meet the objec-
tives. Emphasized are (1) evaluating the effects of air pollutants
on crop yield and quality, (2) identifying and developing plants
tolerant to pollutants, and (3) determining the mechanisms of action
of air pollutants, including assessing the nature of resistance to
pollutants.
The effects of photochemical oxidants on plants have been studied
at Beltsville, Maryland since 1956, when studies were initiated to
determine the cause of weather fleck, a leaf spot injury to tobacco.
By 1959, we reported that oxidants, primarily ozone, caused weather
fleck. In 1966, the research was expanded to studies of other crop
and ornamental plants. By 1968, the research was underway in new
laboratory and greenhouse facilities with a staff of three profes-
sionals. In 1972, some field-oriented research was initiated, using
eight open-top chambers from the Environmental Protection Agency,
Raleigh, North Carolina.
iv
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ABSTRACT
During the past 5 years the impact of photochemical oxidants
on soybeans and snap beans in Maryland and on potatoes in Virginia
and Delaware was assessed with open-top chambers. Experiments with
soybeans were conducted at Queenstown, Maryland from 1973-1975. The
mean yields of four selected soybean varieties grown in open-top
chambers with carbon-filtered air and in plots without chambers were
about the same. However, the mean yields of beans grown in chambers
with nonfiltered air were significantly lower (about 20%). In exper-
iments with snap beans at Beltsville, Maryland from 1972-1974, the
bean yield from one of three varieties tested was decreased 14% by
oxidants, whereas the other two varieties did not show a yield decrease.
Snap beans grown in plots without chambers produced about the same as
those in chambers with nonfiltered air. Results from snap bean exper-
iments conducted in 1975 and 1976 using the circular plot design and
four varieties were similar to those obtained in the first 3 years of
study using row plots.
At Painter, Virginia, in 1975, three of four potato varieties
showed a significant yield reduction (average 30%) in chambers with
nonfiltered air as compared with filtered air. The variety Pungo
yielded the same in the two different chamber environments. Mean
yields for these potato varieties were about the same when grown in the
plots without chambers as when grown in filtered-air chambers, but were
significantly lower when grown in unfiltered chambers. However, mean
yields of potatoes were not significantly different in these three
environments in an experiment at Georgetown, Delaware in 1976.
In 1975, mean hourly oxidant concentrations were higher at Painter,
Virginia than at Beltsville, Maryland but peak values were higher at
Beltsville.
In 1976, a clear plastic tunnel-type chamber tested at Beltsville
proved to be suitable for assessing air pollution impact on snap beans.
The primary advantage over open-top chambers was lower oxidants in the
tunnel chamber with filtered air. However, cultural practices were
more difficult to perform in the tunnel chambers (1.2 m high by 9.1 m
long). A chamber modification to permit easier access to the plants
is suggested.
This report is submitted by the Agricultural Research Service, U.S.
Department of Agriculture in fulfillment of an Interagency Agreement
No. EPA-IAG-D6-0479 sponsored by the Corvallis Environmental Research
Laboratory, U.S. Environmental Protection Agency. The research was
completed September 30, 1976.
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CONTENTS
Foreword ' ill
Preface iv
Abstract v
List of Tables and Figures viii
Acknowledgement xi
1. Introduction 1
2. Conclusions 1
3. Recommendations 2
Section I. Open-Top Chambers 3
1. Materials and Methods 3
Soybeans 3
Snap Beans A
Potatoes 7
2. Results and Discussion 8
Soybeans 8
Snap Beans 8
Potatoes 18
Section II. Oxidant Values Comparison at Beltsville, Maryland
and Painter, Virginia 1975 24
Section III. Tunnel-Type Chambers 28
References 33
Appendix - Microenvironment in Open-Top Chambers 34
vii
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LIST OF TABLES
Number Page
1. Sources of Variation for the Analysis of Variance in a
Soybean Experiment using Open-Top Chambers, Queenstown,
Maryland 3
2. Summary of Results in 1973, 1974, and 1975 with Soybeans
in Three Environments: Chambers with Filtered Air,
Chambers with Nonfiltered Air and Plots with no Cham-
bers at Queens town, Maryland 9
3. Summary of 3 years' Results with Four Soybean Varieties
in Three Environments at Queenstown, Maryland 9
4. Summary of Results with Snap Beans in 1972, 1973 and 1974
(Two Crops each Year) in Three Environments at Belts-
ville, Maryland 10
5. Production of Four Varieties of Snap Beans in Three
Environments, Early Crop 1975, Beltsville 11
6. Production of Four Varieties of Snap Beans in Three
Environments, Late Crop 1975, Beltsville 12
7. Influence of Environment on Yields of Four Snap Bean
Varieties, Early Crop 1976, Beltsville. 14
8. Comparison of Snap Bean Production - Three Environments,
Early Crop 1976 15
9. Comparison of Four Varieties of Snap Beans in Air Pollu-
tion Field Studies, Early Crop 1976..... 16
10. Influence of Environment on Yields of Four Snap Bean
Varieties, Late Crop 1976, Beltsville 17
11. Comparison of Snap Bean Production in Three Environments,
Late Crop 1976 19
12. Comparison of Four Varieties of Snap Beans in Air Pollution
Field Studies, Late Crop 1976 20
viii
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Number
13. Production of Four Snap Bean Varieties in Nonfiltered
Air Chambers as Percent of Production in Carbon-
Filtered Air, 1975 and 1976 21
14. Yield of Four Potato Varieties in Three Environments at
Painter, Virginia 1975 22
15. Yield of Two Potato Varieties in Three Environments at
Georgetown, Delaware in 1976 23
16. Average and Maximum Hourly Oxidant Values at Beltsville,
Maryland, and Painter, Virginia, May-September 1975... 25
17- Oxidant Levels Equal to or greater than 5 and 10 pphm at
Beltsville, Maryland and Painter, Virginia, May-
September 1975 25
18. Frequency Distribution of Mean Hourly Oxidant Values,
9:00 a.m. to 8:00 p.m., May-September 1975 at Belts-
ville, Maryland and Painter, Virginia 26
19. Frequency Distribution of Mean Hourly Oxidant Values,
9:00 p.m. to 8:00 a.m., May-Sepcember 1975 at Beltsville,
Maryland and Painter, Virginia 27
20. Effects of Ambient Oxidants on a Susceptible and a
Tolerant Snap Bean Variety Grown in Tunnel-Type Chambers 30
21. Bean Production in Tunnel-Type Chambers with Nonfiltered
Air and in No-Chamber Plots as Percentage of Production
in Filtered Air 31
22. Correlation Coefficients for Two Snap Bean Varieties in
Three Environments in Studies with Tunnel-Type Chambers 32
FIGURES
Number
1. Open-top chambers in place over circular plots with four
snap bean varieties in each of four quadrants and
similar plots without chambers, 1975-1976. Border row
around chambers as well as plots without chambers.....
ix
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FIGURES (continued)
Number Page
2. Open-top chambers in place over row plots (3 varieties)
and plots without chambers, 1972-1974. Note complete
field cover in 1974 6
3. Chamber ventilation. Air delivery through double-walled
duct. Gusty ambient winds increase internal venti-
lation. Air movement in the vegetation canopy is
damped•«•••»•••••«•.«••••••••••«•«.•..••••««•««•••.•••
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ACKNOWLEDGMENT
The following persons contributed valuable aid and assistance
in completing this study: Mr. Louis P. Rose, Jr. and Mr. W. C. Craig, Jr.
supplied technical assistance; Mr. E. James Koch was consulted on the
statistical methods and analyses; Dr. Alan Heagle, Agricultural Research
Service, U.S. Department of Agriculture, Raleigh, NC provided sug-
gestions on experimental procedure used on the 1972-1974 snap bean
studies; Dr. R. E. Baldwin and Mr. Boyette Graves, Virginia Truck and
Ornamentals Research Station, for conducting the experiments with
potatoes at Painter, VA; and to Dr. Donald F. Fieldhouse, University of
Delaware, Newark for conducting the experiment with potatoes at George-
town, DE.
Acknowledgment is also given to the contributions of:
Dr. J. P. Meiners, Chief, Applied Plant Pathology Laboratory, Beltsville,
MD for suggestions on snap bean culture; Dr. Raymon Webb, Chief,
Vegetable Laboratory, Beltsville, MD for "seed potatoes"; The Asgrow
Seed Co., Kalamazoo, MI for seed of the snap bean varieties Astro, Bush
Blue Lake 290 and Bush Blue Lake 274; and the Gallatin Valley Seed Co.,
Twin Falls, ID for seed of Gallatin 50.
xi
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INTRODUCTION
4
In 1972, the use of "open-top" cylindrical chambers (3 m dia.
and 2.4 m high) to exclude photochemical oxidants was a new approach
to assessing the impact of air pollution on field-grown crops. These
chambers (8) were obtained from the cooperative EPA-USDA research
project at Raleigh, North Carolina. In the first study, three
varieties of snap beans were grown from seedling stage to harvest in
three environments: (1) chambers with carbon-filtered air, (2) cham-
bers with nonfiltered air and (3) field plots without chambers. In
1973 and 1974, additional chambers were constructed to permit simul-
taneous studies on snap beans, soybeans and potatoes.
We also report here on an experiment conducted in 1976 with a
tunnel-type chamber design.
CONCLUSIONS
Experiments in Maryland and nearby locations in Virginia and
Delaware during the past 5 years with open-top chambers placed over
field-grown crops revealed that photochemical oxidants reduced crop
productivity. The amount of the reduction depended on the crop and
the varieties tested. Seasonal variability in oxidant concentrations
and in environmental conditions that influenced plant growth and
response to pollutants affected the results.
Mean yields of soybeans grown in chambers with nonfiltered air
were reduced about 20% as compared with those grown in filtered air.
Since the yields in plots without chambers were about the same as
those in filtered air, a question remains as to how much the yield
reductions may reflect a chamber influence on plant response to
pollutants.
In studies with three snap bean varieties conducted over a 3-year
period, the sensitive Bush Blue Lake 290 variety showed a 14%
reduction in yield attributable to oxidants. Yields of the other
two varieties were not significantly reduced. Studies conducted during
1975-1976 gave similar results. However, BBL 274, which was added
to the experiment, showed about the same yield reduction as BBL 290.
BBL 274 is more widely planted than BBL 290. Snap bean yields were
about the same in plots without chambers as in chambers with non-
filtered air.
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At Painter, Virginia in 1975, yields of three of four potato
varieties tested were reduced significantly (30%) in chamber plots
with nonfiltered as compared with filtered air. However, mean yield
of potatoes in a similar experiment at Georgetown, Delaware in 1976
was not reduced by air pollutants. Potatoes produced higher yields
in field plots without chambers than in chambers.
Oxidant concentrations at Painter, Virginia and Beltsville,
Maryland were very similar during the summer of 1975. Peak con-
centrations were higher at Beltsville but mean concentrations were
higher at Painter.
A tunnel-type chamber (1.2 m high x 9.1 m long) tested in 1976
on snap beans maintained a lower oxidant level in the filtered air
than did adjacent open-top chambers, but was too low to allow
necessary cultural practices to be easily performed.
RECOMMENDATIONS
New approaches are needed to resolve questions raised by the
results obtained with open-top chambers. Results with snap beans
seem adequate, perhaps because with these smaller plants the chamber
effects per se were minimized. • The open-top chambers should be
tested with other species. Known low levels of pollutants,
especially ozone, should be added to some chamber treatments. Exper-
ience with the chambers at other locations in the country would be
beneficial. Chamber modification should be considered along with
other approaches, such as use of chemical protectants on sensitive
and tolerant varieties, for assessing the impact on air pollutants on
field-grown crops.
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SECTION I
OPEN-TOP CHAMBERS
MATERIALS AND METHODS
SOYBEANS
An experiment was designed to answer the question "What is the
effect of oxidant air pollutants on the yield and quality of soybeans
in eastern Maryland?" It was started in 1973 and continued in 1974
and 1975. The varieties selected for the study were York, Dare,
Cutler, and Clark. The experiment was conducted at the Maryland
University Research Farm at the Wye Institute, Queenstown, Maryland,
on a Mattapox silt loam with pH of 6.4. Fertilizer (0-15-30) at
342 kg/ha and a herbicide, trifluralin (a,a,a-trifluoro-2,6-dinitro-lJ,
N_-dipropyl-p_-toluidine), at l.lkg active ingredient/ha were incor-
porated preplant. Supplemental irrigation was provided as needed to
prevent severe wilting.
The sources of variation for the analysis of variance are shown
in Table 1.
TABLE 1. SOURCES OF VARIATION FOR THE ANALYSIS OF VARIANCE IN A
SOYBEAN EXPERIMENT USING OPEN-TOP CHAMBERS, QUEENSTOWN. MD
MAIN EFFECTS
Environments
Filtered air
Nonfiltered
Ambient
Varieties
York
Dare
Cutler
Clark
Positions (quadrants)
NE, NW, SE, SW
Rows
Outer
Inner
ANALYSIS OF VARIANCE
Sources
Total
Replications
Environments (E)
Error a
Varieties (V)
V X E
Positions (P)
P X E
Error b
Rows (R)
R X E
R X V
R X E X V
R X P
R X P X E
Error c
Degrees of
Freedom
95
3
2
6
3
6
3
6
18
1
2
3
6
3
6
27
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The environmental treatments were arranged as four replications
of a randomized complete block design with the positions and
varieties forming a 4 x 4 Latin square as a split plot for each
environment and the rows within a position treated as split-split
plots within this Latin square. Because of the cylindrical chamber
design (3 m dia. x 2.4 m high) three rows 75 cm apart were arranged
in circles. Each plot was divided into equal quarters, referred to
as positions in the analysis of variance. Thus, each quarter had a
long outer row of 1.8 m, and a short inner row of 0.6 m. Varieties
were assigned to quadrants using a separate randomized 4x4 Latin
square for each of the three environmental treatments. Three seeds
were placed in each site spaced 5 cm apart in each row. After 10
days, seedlings were thinned to one per site. Chambers were placed
over plants on designated plots. Four chambers received air drawn
through activated carbon (filtered air) and four received air not
filtered through carbon. Ambient air plots without chambers re-
presented field conditions.
The open-top field chamber with a krene coating was identical to
that described by Heagle, et al. (1). Air under pressure enters the
base of the chamber through many 2.5-cm-diameter holes in the inner
wall of the krene coating, and circulates around the plants before
escaping through the top of the chamber. The air blower assembly
was similar in design to that described by Mandl, et al. (2). Air
flow rates were about 1 km/hr above the plants in the plot centers
when external wind conditions were calm. Each chamber was covered
with a coarse mesh net to minimize wind turbulence.
For more information on the microenvironment conditions in the
open-top chambers, see the Appendix.
Each plant was harvested separately, bagged, identified, and
dried in the greenhouse for 14 days. Seeds were removed, weighed,
and reported as yields in g/plant for each row.
SNAP BEANS
The 1975 and 1976 open-top field chamber experiments conducted
at Beltsville, Maryland with snap beans involved circular plots
similar to those described for soybeans (Figure 1). Each plot con-
sisted of two circular rows 76 cm apart. In 1972, 1973, and 1974,
however, the beans were grown in three row plots which were parallel
and spaced 76 cm apart (Figure 2). Each year the plants were spaced
5 cm apart and all plots had border rows.
Plants were harvested at the proper stage for processing, except
in 1975 they were harvested a few days early because of damage caused
by heavy rains. In 1972, 1973, and 1974, five groups of 5 plants each
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n
Figure 1. Open-top chambers in place over circular plots with four snap bean
varieties in each of four quadrants and similar plots without chambers,
1975-1976. Border row around chambers as well as plots without chambers
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Figure 2. Open-top chambers in place over row plots (3 varieties) and plots
without chambers, 1972-1974. Note complete field cover in 1974.
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were harvested for each variety. In 1975 and 1976, all plants were
harvested. Data included green weight of plants and green and dry
weights of pods. For some crops, mature and immature pods, stem
length, and leaf and stem weights were recorded.
Bush Blue Lake 290, Gallatin 50 and Astro-were used throughout
the 5 years. BBL 290 and Gallatin 50 are processing-type beans and
Astro is a fresh market bean. In 1975 and 1976, Bush Blue Lake 274
was added, since 4 varieties could be tested with the new plot design.
BBL 274 is a processing type more widely grown than BBL 290.
Each year, an early (mid-May to mid-July) and a late crop (late-
July to late-Sept.) were planted. Beans normally mature 55-60 days
after seeding. Oxidant leaf injury was noted as it developed during
the season.
POTATOES
In 1971, photochemical oxidants damaged potato crops on the
Eastern Shore of Virginia (3); consequently, studies with open-top
chambers were initiated in 1973 at Painter, Virginia and continued
to 1976 when they were moved to Georgetown, Delaware. The experimental
design used with potatoes also involved circular plots with a
different variety planted in each quadrant. At Painter, Virginia the
varieties were Pungo, LaChipper, Superior and Norchip. Each plot
contained 8 plants of each variety, with plants spaced 30 cm apart.
The outside row contained six plants of each variety and the inside
row, two plants of each. Cultural practices were similar to those
used for crop production in the area. Each of the three environ-
ments (filtered air chamber, nonfiltered air chamber and plots with-
out chambers) were replicated twice.
In 1976 at Georgetown, Delaware, only two potato varieties were
planted: Norland, which is sensitive to oxidants, and Superior,
which is relatively tolerant. Each environment was replicated four
times.
Oxidants were monitored with Mast Ozone Meters at Beltsville
and Queenstown, Maryland, and at Painter, Virginia to obtain hourly
averages and daily maximum concentrations.
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RESULTS AND DISCUSSION
SOYBEANS
Brief summaries of the soybean studies have been published
(4, 5). There was no significant variety x environment interaction.
Differences in mean seed yields between the filtered and nonfiltered
chambers were greatest in 1973 and least in 1974 (Table 2). Yields
were lowest in 1975. Mean seed yields for soybeans grown in carbon-
filtered chambers and in plots without chambers were not significantly
different (Table 3). Mean seed yields for the varieties grown in
nonfiltered air chambers were reduced significantly (about 20%) com-
pared to the other two environments.
SNAP BEANS
Only summary information on the first 2 years of snap bean
experiments has been published (6, 7). Over the 3-year period (1972-
1974), Gallatin 50 produced significantly greater (7%) weight of green
pods in carbon-filtered air than in plots without chambers. The data
also showed a higher yield (not statistically significant) for this
variety in chambers with nonfiltered than with filtered air (Table 4).
We cannot explain this response. The lower yields in plots without
chambers may be due in part to more leaf diseases in these plots.
BBL 290 and Gallatin 50 were more susceptible to leaf diseases than
was Astro. Astro was also the most tolerant to oxidants, as evidenced
by the similar yields in the three environments.
In 1975, snap beans were first grown in circular plots and com-
pared with those grown in previous years in row plots (Figures 1 and
2). Photochemical oxidants did not reduce yields of either the early
or late crops that year (Tables 5 and 6). In the early crop, the
chamberless plots produced higher yields than chamber plots because
of severe drought late in June. Physical measurements have shown that
plants in chambers have greater moisture stress. When the early crop
plants were half grown, moisture stress was sufficient to induce
wilting, especially in the chamber plots. The drought was followed
by heavy rains (about 21 cm during a week). The soil became water-
logged, resulting in root damage and most pods in contact with soil
developing rot. Plants were harvested a few days early to minimize
the damage. Actually 1/3 to 1/2 of the pods were under size ( 7 cm
or less). Before the harvest was complete (2 days) the plants were
severely wilted, indicating root damage. The replications harvested
last had significantly lower green pod weight due to loss of the
moisture content. Under these environmental conditions Gallatin 50
produced significantly more green weight of beans than the other
8
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TABLE 2. SUMMARY OF RESULTS IN 1973, 1974, AND 1975 WITH SOYBEANS
IN THREE ENVIRONMENTS: CHAMBERS WITH FILTERED AIR, CHAMBERS
WITH NONFILTERED AIR AND PLOTS WITH NO CHAMBERS AT
QUEENSTOWN, MARYLAND
Year
1973
1974
1975
Yield per plant -
Chambers Chambers
nonfiltered filtered
air (NF) air (F)
g g
21.5 b 30. 4a
19.9 be " 21.8 b
14.0 d 16.9 cd
• environment a
No Ave
chambers
g g
31. la 27.
21.2 b 21.
18.1 be 16.
NF/F
xlOO
%
7a 70.7
Ob 91.3
3 c 82.8
Average 18.5 b 23. Oa 23. 5a
Values not followed by the same letter are significantly different at
5% level, Duncan's multiple range test.
TABLE 3. SUMMARY OF 3 YEARS' RESULTS WITH 4 SOYBEAN VARIETIES IN 3
ENVIRONMENTS AT QUEENSTOWN, MARYLAND
Variety
Dare
York
Cutler
Clark
Yield per plant
Chambers Chambers
nonfiltered filtered
air (NF) air (F)
g g
21.3 27.0
19.5 22.4
17.9 22.1
15.2 20.6
- environment
No Ave .
chambers
g g
25.2 24. 5a
26.7 22. 9a
21.2 20.4 b
20.7 18.8 b
NF/F
xlOO
78.9
87.1
81.0
73.8
Average
18.5 b
23. Oa
23.5a
Values not followed by the same letter are significantly different,
Duncan's multiple range test.
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TABLE 4. SUMMARY OF RESULTS WITH SNAP BEANS IN 1972, 1973, AND 1974
(TWO CROPS EACH YEAR) IN THREE ENVIRONMENTS UTILIZING OPEN-
TOP CHAMBERS AT BELTSVILLE, MARYLAND
1 2
Yield per plant in three environments
Character
and
variety
Plant green wt.
BBL 290
Astro
Gal. 50
Pods green wt.
BBL 290
Astro
Gal. 50
Pods dry wt .
BBL 290
Astro
Gal. 50
Chambers
nonf iltered
air (NF)
g
108.8 c
118. 9ab
121.4ab
57.4 d
58.1 cd
65. Sab
5.5 de
5.9 cd
6.5ab
Chamber
filtered
air (F)
g
125. 8a
123.2ab
117. 4b
66. 9a
59.9 cd
62.1 be
6.8a
6.1 be
6.1 be
No
chamber
g
109.6 c
120. Sab
109.0 c
57.9 cd
60.2 cd
57.7 d
4.9 f
5.5 de
5.4 e
NF/F
xlOO
86.5
96.5
103.4
85.8
97.0
105.2
80.9
96.7
106.6
Four replications (plots) of each environment with 5 groups of 5 plants
each harvested of each variety in each plot. Each value is the aver-
age performance in 6 experiments; i.e., 3 years and 2 crops each year.
values not followed by the same letter are significantly different at
5% level, Duncan's multiple range test.
10
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TABLE 5. PRODUCTION OF 4 VARIETIES OF SNAP BEANS IN 3 ENVIRONMENTS,
EARLY CROP 1975, BELTSVILLE
Yield per plant - environment
Character Chambers Chambers No NF/F
Variety nonfiltered filtered chambers xlOO
g g g
Plant green wt.
BBL 290 84.3 def 87.5 cde 95.2 c 96.3
Astro 81.8 ef 78.1 f 95.8 c 104.7
Gal. 50 109.7 b 105.1 b 118.6a 104.4
BBL 274 93.6 c 92.3 cd 104.0 b 101.4
Pods fresh wt.
BBL 290 37.9 de 40.5 cd 49.1 be 93.6
Astro 23.6 f 22.0 f 36.5 de 107.3
Gal. 50 55.4 b 54.7 b 68.Oa 101.3
BBL 274 31.2 ef 29.0 ef 43.1 cd 107.6
Pods dry wt.
BBL 290
Astro
Gal. 50
BBL 274
2.95 cde
2.18 ef
4 . 02ab
2.46 def
2.75
2.03
4.21a
2.48
cdef
f
def
3.46 be
3.01 cd
4.38a
3.15 cd
105.8
107.4
95.5
99.2
values not followed by the same letter are significantly different
at 5% level, Duncan's multiple range test.
11
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TABLE 6. PRODUCTION OF 4 VARIETIES OF SNAP BEANS IN 3 ENVIRONMENTS, LATE
CROP 1975, BELTSVILLE
Character
Variety
Yield per plant - environment
Chambers Chambers No
nonfiltered filtered chambers
air (NF) air (F)
NF/F
xlOO
Plant green wt.
BBL 290
Astro
Gal. 50
BBL 274
Pods fresh wt.
BBL 290
Astro
Gal. 50
BBL 274
g
75.5 d
95.2 abc
91.0 abed
87.5 abed
32.7 abed
31.7 abed
36.8 ab
27.3 bcde
g
85.0 abed
86.0 abed
86.0 abed
97.5 ab
38.1 a
33.3 abed
34.3 abc
30.4 abed
g
80.0 cd
82.9 abed
81.7 bed
93.2 abc
32.9 abed
19.8 e
25.0 cde
23.6 de
88.8
110.7
105.8
89.7
85.8
95.2
107.2
89.8
Pods
BBL
dry wt.
290
Astro
Gal.
BBL
50
274
2
2
2
1
.56abc
.37abcd
.73ab
.95 cde
2
2
2
2
.89a
.42abc
.49abc
.09 be
2.
1.
1.
1.
Slabc
43
e
84 cde
68
de
88.
97.
109.
93.
6
9
6
3
Values not followed by the same letter are significantly different at
5% level, Duncan's multiple range test.
12
-------
varieties.
The experiment with the late bean crop was on a new location
having lighter textured soil and better drainage. Plant growth was
good, until heavy rains late in September caused some damage. As
with the early crop, green pods were harvested a few days before they
were ready for processing or marketing. Oxidant concentrations during
September were relatively low. Yields were similar for all varieties
(Table 6). Astro, however, produced significantly less in the no-
chamber plots than in chamber plots. Yields in the outside rows were
significantly higher than in the inside rows. There was also a
significant position effect. In the unfiltered chambers, plots in
the southwest quadrant produced more than those in the northwest or
southeast quadrant.
1976 Early Crop
In 1976 the experimental plantings were in circular plots. Bean
yields for the early crop were similar for all environments (Tables 7
and 8). The plants in filtered air had significantly more leaves than
plants in the chamberless plots (Table 8). The ratio of leaves to
stems and the percent dry matter in pods were significantly higher in
all chamber plots than in the plots without chambers, indicating a
chamber effect.
The performance by each variety is shown by data in Table 9.
BBL 290 produced significantly less plant green weight and less leaf
and stem weight than the other varieties. The reduced weights may be
due to the greater susceptibility of BBL 290 to a virus disease which
was apparently prevalent in several Eastern States during June. The
virus was either plant stunt virus or yellow mosaic virus according
to J. P. Meiners, Agricultural Research Service, USDA, Beltsville,
Maryland. It stunted the plants to various extents and even killed
some plants.
1976 Late Crop
In the late crop, the chamber experiments indicated that photo-
chemical oxidants reduced the plant growth of Astro and BBL 274
significantly (Table 10)- Pod yields of BBL 274 were reduced 22%.
In filtered air BBL 274 produced almost double the bean yield of BBL
290. BBL 290 yields were reduced by rust, which was especially severe
in .the field plots without chambers. Because of the rust, differences
in the yields of BBL 290 in filtered and nonfiltered air were not
significant, even though the variety is more sensitive to oxidants
than the other varieties. Other research has shown that rust lesions
give localized, protection from oxidant injury (8).
13
-------
TABLE 7- INFLUENCE OF ENVIRONMENT ON SNAP BEAN YIELDS WITH 4 VARIETIES
EARLY CROP 1976, BELTSVILLE
Yield per plant-environment3
Character
and
Varlp»-v
Plant green wt.
BBL 290
Astro
Gal. 50
BBL 274
Pods green wt.
BBL 290
Astro
Gal. 50
BBL 274
Pods dry wt.
BBL 290
Astro
Gal. 50
BBL 274
Chamber
nonfiltered
air (NF)
g
114.4 d
164. 6a
170. 8a
162. 7a
59.1 b
59.0 b
78.2ab
71.9ab
6.22a
5.98a
7.51a
6.16a
Chamber
filtered
air (F)
g
132.8 bed
168. 7a
145.7abc
175. 4a
65 . 9ab
65. lab
64.7ab
82. 6a
7.00a
6.56a
6.36a
7.18a
No
chamber
g
126.9 cd
156. 4ab
161. 6ab
174. 6a
62. lab
59.3 b
72. lab
76.0ab
6.00a
5.50a
6.11a
6.09a
NF/F
xlOO
86.1
97.6
117.2
92.8
89.7
90.6
120.8
87.0
88.9
91.2
118.1
85.8
a Values not followed by same letter are significantly different at 5%
level, Duncan's multiple range test.
14
-------
TABLE 8. COMPARISON OF SNAP BEAN PRODUCTION - THREE ENVIRONMENTS,
EARLY CROP 1976
Yield per plant-environment3
Character
Plant green wt. g
Pods green wt. g
Pods dry wt. g
Leaves/plant g
Stems/plant g
Ratio* leaves/stem
Pods> % dry matter
Chamber
nonfiltered
air (NF)
153.1 a
67.0 a
6.47a
68.5 ab
57.6 a
1.20a
9.78a
Chamber
filtered
air (F)
155.7 a
69.6 a
6.78a
71.4 a
62.0 a
1.15a
9.77a
No
chamber
154.9 a
67.4 a
5.92a
63.2 b
60.9 a
1.04 b
8.81 b
NF/F
xlOO
98.3
97.1
95.4
95.9
92.9
104.3
100.1
a Values not followed by the same letter are significantly different at
5% level, Duncan's multiple range test.
15
-------
TABLE 9. COMPARISON OF 4 VARIETIES OF SNAP BEANS IN AIR POLLUTION
FIELD STUDIES, EARLY CROP 1976
Variety3
Character
Plant green wt. g
Pods green wt. g
Pods dry wt. g
Leaves/plant g
Stems/plant g
Ratio, leaves/stem
Pods, % dry matter
BBL
290
124.7 b
62.4 b
6.41a
51.6 c
49.0 b
l.OSa
10.17a
Astro
163.2 a
61.1 b
6. Ola
78.2 a
66.9 a
1.17a
9.86a
Gal. 50
159.4 a
71.7 ab
6. 66a
69.4 b
61.5 a
1.14a
9.37 b
BBL
274
170.9 a
76.8 a
6.48a
71.5 ab
63.2 a
1.15a
8.41 c
a Values not followed by the same letter are significantly different at
5% level, Duncan's multiple range test.
16
-------
TABLE 10. INFLUENCE OF ENVIRONMENT ON YIELDS OF 4 SNAP BEAN VARIETIES
LATE CROP 1976, BELTSVILLE
Character
and
Variety
Plant green wt.
BBL 290
Astro
Gal. 50
BBL 274
Pods green wt.
BBL 290
Astro
Gal. 50
BBL 274
Pods dry wt.
BBL 290
Astro
Gal. 50
BBL 274
Yield
Chamber
nonfiltered
air (NF)
g
70.0 ef
102.9 cd
114.9 be
112.8 be
31.5 e
51.2 bed
59.7 b
54.7 bed
2.69 e
4.60 bed
4.85 b
4.57 bed
per plant-environment3
Chamber
filtered
air (F)
g
81.0 e
122.3 b
119.8 b
143.8 a
35.5 e
57.1 be
59.6 b
70.1 a
3.00 . e
4.91 b
4.79 be
5.85a
No
chamber
g
64.1
97.9 d
95.2 d
108.0 bed
18.5
48.4 cd
47.9 d
52.7 bed
1.47
4.01 cd
3.87 d
4.11 bed
NF/F
xlOO
f 86.3
84.1
95.9
78.4
f 88.7
89.4
100.2
78.0
f 89.7
93.7
101.3
78.1
Values not followed by the same letter are significantly different at
5% level, Duncan's multiple range test.
17
-------
Average green weights of plants and pods, and weights of mature
pods and leaves were significantly higher in the chambers with
filtered air than in chambers with nonfiltered air or in plots with-
out chambers (Table 11). As might be expected, oxidants depressed
leaf weights more than bean yields, 24% vs 11% respectively. Although
BBL 274 showed the greatest yield reduction due to oxidants, it still
had the highest yields in all environments (Table 12). Gallatin 50
had significantly more immature pods (<10 cm) than the other
varieties.
The data for the 1975 and 1976 studies using the new circular
experimental design are summarized in Table 13. Although the
statistical treatment of the combined data is not complete, the
results indicate that oxidants depressed the yields of BBL 290 an
average of 10%, whereas Gallatin 50 produced more in chambers with
nonfiltered air than in the filtered air. Thus, the experimental
design using circular rows gave results very similar to those
obtained with row plots (Table 4).
POTATOES
Summary data for the 1975 study at Painter are presented (Table
14). Yield reductions attributable to oxidants average 24 percent.
Pungo, the most tolerant variety, produced about the same yields in
all environments. The yield of Superior was reduced 41%. At harvest,
Pungo had significantly more vine weight in the filtered air. Perhaps
if the harvest had been delayed, the greater vine weight of Pungo
would have resulted in more tuber weight in the filtered air, as
happened with the other varieties.
At Georgetown in 1976, yields of the two potato varieties did
not differ significantly in the three environments (Table 15).
Seasonal oxidant concentrations were relatively low. Although oxidant-
induced leaf injuries developed in July, especially on Norland in the
nonfiltered chambers and in plots without chambers, they apparently
were not sufficient to reduce tuber yield.
18
-------
TABLE 11. COMPARISON OF SNAP BEAN PRODUCTION IN THREE ENVIRONMENTS,
LATE CROP 1976
Yield per plant-environment
Character
Plant green wt. g
Pods green wt. g
Pods dry wt. g
Pods mature g
Pods immature g
Stem length (cm)
Leaves/plant g
Stems/plant g
Ratio, leaves /stem
Pods dry matter %
Chamber
non filtered
air (NF)
100.1 b
49.3 b
4.18a
44.2 b
4.4 b
38.7 ab
43.3 b
21.7 a
2.10a
8.48a
Chamber
filtered
air (F)
116.8 a
55.6 a
4.64a
49.6 a
5.3 ab
43.8 a
57.3 a
27.4 a
2.10a
8.33a
No
chamber
91.3 b
41.9 c
3.37 b
35.2 b
6.0 a
34.9 b
43.3 b
24.3 a
l.Sla
8.03a
NF/F
xlOO
85.7
88.7
90.0
89.1
83.0
88.4
75.6
79.2
100.0
100.8
Values followed by a different letter are significantly different at
5% level, Duncan's multiple range test.
19
-------
TABLE 12. COMPARISON OF 4 VARIETIES OF SNAP BEANS IN AIR POLLUTION
FIELD STUDIES, LATE CROP 1976a
Yield per plant-variety
Character
Plant green wt. g
Pods green wt. g
Pods dry wt. g
Pods mature g
Pods immature g
Stem length (cm)
Leaves/plant g
Stems/plant g
Ratio, leaves/stem
Pods dry matter %
BBL
290
71.7 c
28.5 c
2.39 b
22.5 c
5.3 b
35.7 b
43.5 b
21.0 b
2.14a
8.28 b
Astro
107.7 b
52.3 b
4.51a
49.3 ab
3.0 c
39.1 a
46.7 ab
25.5 ab
1.87 b
8.59a
Gal. 50
110.0 b
55.7 ab
4.50a
47.3 b
7.6 a
41.1 a
47.5 ab
24.1 ab
1.99ab
8.11 b
BBL
274
121.5 a
59.2 a
4.84a
53.0 a
5.1 b
40.6 a
54.2 a
27.2 a
2.00ab
8.15 b
a Values not followed by the same letter are significantly different at
5% level, Duncan's multiple range test.
20
-------
TABLE 13. PRODUCTION OF 4 SNAP BEAN VARIETIES IN NONFILTERED AIR
CHAMBERS AS PERCENT OF PRODUCTION IN CARBON-FILTERED
AIR, 1975 AND 1976
Variety
1975
Early
Late
1976
Early
Late
Ave.
BBL 290
Astro
Gal. 50
93.6
107.3
101.3
BBL 274 107.6
85.8
95.2
107.2
89.8
89.7
90.6
120.8
87.0
88.7
89.4
100.2
78.0
89.5
95.6
107.4
90.6
Average 102.5
94.5
97.0
89.1
21
-------
TABLE 14. YIELD OF FOUR POTATO VARIETIES IN THREE ENVIRONMENTS AT
PAINTER, VIRGINIA, 1975a b
Tuber yield per plant-environment0
Variety
Pungo
LaChipper
Superior
Norchip
Average
Nonfiltered
air (NF)
g
375.9abc
249.9 c
301.3 be
440.3abc
341.8 b
Carbon-
filtered
air (F)
g
364.4abc
419.8abc
516. 8a
4 91. Sab
448. 2ab
No
chambers
g
379.3abc
553. 3a
565. 5a
509. 6ab
501. 9a
NF/F
x 100
103.1
59.5
58.3
89.5
76.3
aEight plants per plot. Two replications.
Cooperation of Dr. R. Baldwin and Mr. B. Graves, Truck Crops
Substation, Eastern Shore, Painter, Va.
°Values not followed by the same letter are significantly different
at the 5 percent level, Duncan's multiple range test.
22
-------
TABLE 15. YIELD OF TUBERS FOR TWO VARIETIES IN THREE ENVIRONMENTS AT
GEORGETOWN, DELAWARE, IN 1976a
Tuber yield per plant in environments
Character
Variety
Tuber wt./g
Norland
Superior
Plant wt./g
Norland
Superior
Tuber no.
Norland
Superior
Chamber
nonfiltered
air (NF)
878.6
910.3
138.9
215.9
11.8
12.1
Chamber No
filtered chamber
air (F)
943.1 990.4
845.8 837.6
131.4 88.9
170.3 115.8
13.8 12.1
12.1 9.9
NF/F
x 100
93.2
107.6
105.7
126.8
85.5
100.0
aCooperation University of Delaware, Dr. D. Fieldhouse.
''Based on F tests in the analysis of variance tuber production in
the different environments were not significantly different.
23
-------
SECTION II
OXIDANT VALUES COMPARISON AT BELTSVILLE, MARYLAND
AND PAINTER, VIRGINIA 1975
Oxidants were monitored with Mast ozone sensors throughout 1975
at Beltsville, Maryland .and during May through September at Painter,
Virginia. A sulfur dioxide (S02> scrubbing column was used at
Beltsville but not at Painter, Virginia. Some experience with S02
scrubbers at Painter indicated no S02 interference. The 1975 oxidant
data at Painter and Beltsville were representative of those obtained
in other years.
The mean oxidant values in 1975 were higher at Painter, Virginia
than at Beltsville for May - September (Table 16). However, the
maximum hourly values were higher at Beltsville (17.0 pphm, July 31,
4 p.m. at Beltsville, and 11.7 pphm, July 31, 1 p.m. at Painter). The
mean hourly concentration was highest at 3 p.m. (5.0 pphm) at Beltsville
and at 4 p.m. (5.1 pphm) at Painter, Virginia.
In each month, May through September (Table 17), the oxidant
concentration was 5 pphm or greater for more hours at Painter (729
hours) than at Beltsville (469 hours). However, the concentration
was 10 pphm or greater for only 2 hours during the season at Painter
compared to 42 hours at Beltsville. Previous experience indicates
that several hours at an oxidant concentration of 5 pphm by Mast is
a threshold value for causing visible injury to sensitive plants. At
10 pphm, the oxidant injury to vegetation is much more prevalent and
we sometimes refer to the situation as an air pollution episode.
The frequency distribution of the oxidant values from 9 a.m. to
8 p.m. and 9 p.m. to 8 a.m. for May through September are presented
in Tables 18 and 19, respectively. In the daytime period, oxidant
peak values were higher at Beltsville. However, the oxidant value
with greatest frequency was 4.5 pphm for Painter, Virginia, as com-
pared with 1.5 pphm for Beltsville, Maryland. No values at Painter
were as low as 0.5 pphm.
Oxidant values during the 9 p.m. to 8 a.m. period reached the
same maximum, 8.5 pphm, at the two locations; but in general, oxi-
dants were higher also during this 12-hour period at Painter than at
Beltsville. The oxidant value of greatest frequency was 1.5 pphm at
Beltsville, as compared with 2.5 pphm at Painter.
24
-------
TABLE 26. AVERAGE AND MAXIMUM HOURLY OXIDANT VALUES AT BELTSVILLE,
MARYLAND, AND PAINTER, VIRGINIA, MAY - SEPTEMBER 1975
Oxidant value
Mean
Month
May
June
July
August
September
Maryland
2.67
2.98
3.17
3.28
1.90
Virginia
3.67
3.39
3.47
3.78
2.90
(Mast - pphm)
Maximum
Maryland
11.2
12.4
17.0
14.0
7.3
Virginia
9.0
8.3
11.7
10.8
6.8
TABLE 17. OXIDANT LEVELS EQUAL TO OR GREATER THAN 5 AND 10 pphm AT
BELTSVILLE, MARYLAND, AND PAINTER, VIRGINIA, MAY -
SEPTEMBER 1975
Hours 5 pphm
or greater
Month
May
June
July
August
September
Maryland
57
119
125
143
25
Total 469
Virginia
138
139
165
227
60
729
Hours 10 pphm
or greater
Maryland
2
7
16
17
0
42
Virginia
0
0
1
1
0
2
25
-------
TABLE 18. FREQUENCY DISTRIBUTION OF MEAN HOURLY OXIDANT VALUES,
9:00 A.M. TO 8:00 P.M., MAY - SEPTEMBER 1975, AT
BELTSVILLE, MARYLAND, AND PAINTER, VIRGINIA
Oxidant
Value
(pphra)
17.5
16.5
15.5
14.5
13.5
12.5
11.5
10.5
9.5
8.5
7.5
6.5
5.5
4.5
3.5
2.5
1.5
0.5
Percentage
oxidant
Maryland
.02
.02
.02
.05
.02
.23
.30
.30
.56
.87
1.15
2.78
5.35
8.77
14.74
21.14
36.09
7.58
at indicated
values
Virginia
.00
.00
.00
.00
.00
.00
.06
.06
.54
1.53
4.90
12.51
19.00
21.12
20.83
15.10
4.37
.00
100.00
100.00
26
-------
TABLE 19. FREQUENCY DISTRIBUTION OF MEAN HOURLY OXIDANT VALUES,
9:00 P.M. TO 8:00 A.M., MAY - SEPTEMBER 1975, AT
BELTSVILLE, MARYLAND, AND PAINTER, VIRGINIA
Oxidant
Value
(pphm)
8.5
7.5
6.5
5.5
4.5
3.5
2.5
1.5
0.5
Percentage
oxidant
Maryland
.02
.35
.71
1.11
3.11
10.41
23.50
43.63
17.16
at indicated
values
Virginia
.18
.06
.54
3.70
9.98
16.61
26.22
24.07
18.64
100.00
100.00
27
-------
SECTION III
TUNNEL-TYPE CHAMBERS
Research results of the past 5 years have shown that open-top
chambers supplied with either carbon-filtered or nonfiltered air are
useful in assessing the impact of oxidant air pollution on crops.
However, even with low windspeeds, some unfiltered air enters from
the open top and mixes with filtered air within the chamber. Con-
sequently, the chamber's efficiency in protecting the enclosed plants
from oxidants is reduced. The above is not a problem with a long
tunnel-type chamber having an open end. Such a chamber was designed
and tested with snap beans during 1976.
MATERIALS AND METHODS
Two tunnel-type chambers (1.5 m wide, 1.2 m high, and 9.1 m long)
were made using 4 mil, clear polyethylene plastic supported at 1.8-m
intervals with six U-shaped, 1.8-cm-diameter, tubular aluminum supports.
The supports were set in larger pipe (1 m x 2.5 cm diameter) driven
about 0.5 m into the ground. Both edges of the plastic were placed
in 10-cm-deep trenches running the length of the chambers. The edges
were covered with soil until the plastic was stretched uniformly over
the supports. At one end, a 2-m length of the plastic was shaped into
a cone to permit attachment to a 46-cm-diameter duct from the blower.
To help straighten the air flow entering the chamber, two pieces of
plastic "egg crate" (1.2 mxl.2mxl.2 cm) with 1.2-cm square
openings were set upright 15 cm apart and attached to the first
section of tubular aluminum supporting the plastic. The other end of
the chamber was open, although a buffer shield was erected about 0.5 m
from the open end to prevent high winds from blowing into the tunnel.
Each chamber had one row of an oxidant-sensitive cultivar of snap bean,
Bush Blue Lake 290, and a row containing a tolerant cultivar, Astro.
The rows were 76 cm apart. Seeds were planted July 27 and the cham-
bers were put in place August 18 after the seedlings were thinned to
5-cm spacings and the first cultivation was done. Plants were
watered by drip irrigation using Dupont Viaflow tubing on each side
of the two rows. When the chambers were first set in place, the
plants had one fully expanded trifoliate. On August 25 the beans
were sidedressed with 560 kg/ha of 10-6-4 fertilizer. The side-
dressing was applied to help correct a nitrogen deficiency and reduce
the irregularity in bean growth caused by differences in previous
cropping of the plot land. Plants were harvested on September 27,
and data were taken on each plant. In addition, the plants between
each set of metal supports were kept separate so the yields could be
determined on a plot (5) as well as a plant basis.
28
-------
RESULTS
On sunny days when the bean plants were small, air temperature
in the center of the chamber was 3 to 6° C above ambient. On cloudy,
days the chamber temperature was about the same as ambient. After
plants were in bloom, the chamber temperature above the plant canopy
was about the same as ambient, even on sunny days. This was probably
due to the cooling effects of the moisture transpired from the plants
and soil, and to the increased air speed through the chamber as the
plant canopy filled more of the chamber. When the plants were in
full bloom, they occupied about half of the chamber space.
Plant green weight was significantly greater in filtered air
than nonfiltered air (about 20%) for both the susceptible and tolerant
varieties (Tables 20 and 21). The green weight bean yield was
significantly greater (17%) in filtered air for the susceptible vari-
ety but not for the tolerant variety (difference 13%). The susceptible
variety was severely injured by bean rust, especially in the ambient
chamberless plots. There was very little rust in the chambers. Bean
yields of BBL 290 in the chamberless plots were only a third of those
in filtered air. By contrast, the oxidant-tolerant variety Astro was
also quite rust tolerant. Its yield was significantly greater in the
no-chamber plot than in the nonfiltered chamber plot.
Correlation coefficients were highly significant when comparing
pod dry weight and green weight and pod weight with plant weight for
both varieties in the three environments (Table 22). As might be
expected, the correlation was very high between pod green and dry
weights (>r = .97). Lowest correlation between pod and plant weights
was in the no-chamber plots for the oxidant- and rust-susceptible
variety Bush Blue Lake 290.
DISCUSSION
Tunnel-type chambers keep oxidant concentrations lower around
the vegetation than do open-top chambers. In the nonfiltered air
chambers, plant weights of even the oxidant-tolerant variety, Astro,
were reduced nearly the same (about 20%) as for the oxidant-susceptible
variety. Although both varieties of beans grew well in the chambers,
Astro produced more beans in the no-chamber plots than in the cham-
bers.
A disadvantage with the tunnel-type chambers is the difficulty
in cultivating the soil and applying insecticides within the chamber.
We may be able to correct this by cutting the chamber top along one
side so the top can be periodically opened for access. The chamber
could be closed by taping the cut edges together onto a metal base
fastened between the six frames that support the plastic.
29
-------
TABLE 20. EFFECTS OF AMBIENT OXIDANTS ON A SUSCEPTIBLE AND A TOLERANT
SNAP BEAN VARIETY GROWN IN TUNNEL-TYPE CHAMBERS3
Variety
Susceptible,
Bush Blue Lake
Environment
290
Nonfiltered chamber
Filtered chamber
No chamber
Plant
green
weight
g
93.4 c
119. 5a
51.6 d
Pods
green
weight
g
47.4 be
57. 5a
17.4 d
Pods
dry
weight
g
4.12 b
4.84ab
1.53 c
Tolerant,
Astro
Nonfiltered chamber 101.1 be 42.8 c 3.97 b
Filtered chamber 125.5a 49.4abc 4.37ab
No chamber 110.Oab 54.9ab 5.13a
aValues not followed by the same letter are significantly different
at the 5 percent level, Duncan multiple range test.
30
-------
TABLE 21. BEAN PRODUCTION IN TUNNEL-TYPE CHAMBERS WITH NONFILTERED
AIR AND IN NO-CHAMBER PLOTS AS PERCENT OF PRODUCTION IN
FILTERED AIRa
Plant Pods Pods
Variety Environment green green dry
weight weight weight
Susceptible,
Bush Blue Lake 290
Nonfiltered air chamber 78 83 85
Filtered air chamber 100 100 100
No chamber 43 30 32
Tolerant,
Astro
Nonfiltered air chamber 81 87 91
Filtered air chamber 100 100 100
No chamber 88 111 117
a
See Table 20 for weights and statistical significance.
31
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TABLE 22. CORRELATION COEFFICIENTS FOR TWO SNAP BEAN VARIETIES IN
THREE ENVIRONMENTS IN STUDIES WITH TUNNEL-TYPE CHAMBERS11
Environment
and
Parameter
Measured
Nonfiltered air chaml
Plant green wt.
Pods green wt.
Pods dry wt.
Filtered air chamber
Plant green wt.
Pods green wt.
Pods dry wt.
No chamber
Plant green wt.
Pods green wt.
Pods dry wt.
"
Bush Blue Lake 290
Plant Pods Pods
green green dry
wt . wt . wt .
>er
1.00
.97 1.00
.96 .99 1.00
1.00
.97 1.00
.94 .97 1.00
1.00
.89 1.00
.86 .99 1.00
Astro
Plant Pods Pods
green green Dry
wt. wt. wt.
1.00
.94 1.00
.94 .99 1.00
1.00
.90 1.00
.86 .98 1.00
1.00
.98 1.00
.96 .99 1.00
aAll correlations are significant at 1 percent level.
32
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REFERENCES
1. Heagle, A. S., D. E. Body and W. W. Heck. 1973. An open-top
field chamber to assess the impact of air pollution on plants.
J. Environ. Qual. 2 (3):365-368.
2. Mandl, R. H., L. H. Weinstein, D. C. McCune and M. Keveny. 1973.
A cylindrical open-top chamber for the exposure of plants to air
pollutants in the field. J. Environ. Qual. 2 (3):371-376.
3. Heggestad, H. E. 1973. Photochemical air pollution injury to
potatoes in the Atlantic Coast States. Amer. Potato J. 50 (9):
315-328.
4. Howell, R. K. 1974. Soybean seed yields influenced by oxidant
air pollution (Abs.) Proc. Amer. Phytopath. Soc. Vol. 1: p. 151.
5. Howell, R. K., E. J. Koch and L. P. Rose. 1976. Agronomy
Abstracts. Field assessment of air pollution induced soybean
yield losses, p. 84.
6. Heggestad, H. E., A. S. Heagle and J. P. Meiners. 1973. Effects
of oxidant air pollutants on yields of green beans. Abstracts
2nd International Congress of Plant Pathology, Minneapolis, Minn.,
Sept., 1973.
7. Heggestad, H. E. 1975. Plant protection from oxidant air
pollutants. In. Reports and information, Section IV, Plant
protection in relation to human health and environmental pollution.
VIII International Plant Protection Congress Moscow, pp. 114-118.
8. Yarwood, C. E. and J. T. Middleton. 1954. Smog injury and rust
infection. Plant Physiol. 29:393-395.
33
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APPENDIX
MICROENVIRONMENT IN OPEN-TOP CHAMBERS
Abstract
Air flow, light, temperature, pollutant concentration, and soil
moisture parameters were measured on sunny and cloudy days in open-top
field chambers on snap bean, potato, and soybean plots. Chamber air
blowers produced air flow in the chambers of about 0.5 m sec"-*- (1 mph).
Gusty winds increased chamber ventilation because of air entering
from the top. During periods of high solar lighting, photosynthetically
active radiation (PAR) in shaded areas within the chambers were 50-60%
of the intensities of the brightest parts of the chambers. On cloudy
days, light and temperatures inside and outside the chambers were
about the same. Chamber temperatures were closely related to solar
radiation, ventilation rates, and ground cover. Chamber filters
(charcoal) removed 80% or more of the oxidants passed through them;
however, on windy days oxidant concentrations within filtered air
chambers averaged about 50% of the ambient levels due to ingress from
the open top. Chamber "rainshadows" and "light shadows" affected the
soil moisture as did plant age and condition which affected the evapo-
transpiration potential.
Periodic measurements made during the summer months allow the
following general statements to be made about the microenvironmental
conditions within the open-top chambers:
Wind- and Air-Flow Parameters:
The ambient wind direction during the summertime was from the
northwest. During gusty periods, the leeward (southeastern) portion
of the chamber interiors received more ventilation than the windward
side due to downdrafts of ambient gusts entering the chambers from
the top. During calm periods, the interior ventilation resulted
essentially from the chamber air-blower input. Wind speeds above the
plants produced by the blowers were approximately 0.5m sec~l
throughout most of the chamber interior, but decreased to about
0.25 m sec"-'- near the center portion. Very near the chamber walls
where jet streams entered from the inlet duct holes, wind speeds of
2-8 m sec"! were measured. Within 1/2 meter of the duct walls the
jet streams merged providing more generalized chamber flows. Below
the plant canopy surface level, ventilating wind speeds decreased to
about 0.1-0.3 m sec"-'- near the ground. Air flow characteristics of
the chambers are shown by Figure 3.
35
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Figure 3. Chamber ventilation. Air delivery through double-walled
duct. Gusty ambient winds increase internal ventilation. Air
movement in the vegetation canopy is damped.
Light intensities were highest in the northern parts of the
chamber interiors. Substantial shading of the southerly portions
occurred during periods of direct solar lighting. The shaded areas
changed as the sun's angle rotated. Solar insolation was least where
chamber bracings or the double thicknesses of the lower half of the
plastic chamber walls cast visible shadows. Light intensities in the
most extensively shaded areas (measured above the plants) were reduced
to ca. 50-60% of the light intensities in the "unshaded" areas during
periods of high incident sunlight. Light intensities in the brightest
parts of the chambers were 70-90% of the intensities measured outside
the chambers. During overcast periods light intensities, resulting
from diffuse skylight, were essentially the same throughout the
chamber cross sections and closely approximated outside light inten-
sities.
Below the plant canopy surfaces, light intensities decreased
rapidly. Less than 5-10% of the photosynthetically active radiation
(X: 400-700 my) reached the ground for dense canopies.
Temperature:
Temperatures within the chambers were closely related to chamber
light intensities. During high solar radiation and calm periods,
maximum temperature gradients of 6° C were measured over (near) bare,
dry ground across the chambers between the most shaded and brightest
36
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locations. Chamber temperatures varied from several degrees centi-
grade (<4° C) above ambient temperatures in "hot spots" to 1-3° C
below ambient temperatures in shaded parts. During periods of low
light (overcast skies), temperature varied little over the cross
section.
Plant canopies effectively dissipate absorbed solar energy
through evapotranspiration. Therefore, temperature gradients are
expected to be less over vegetation than over dry "black-body"
surfaces. Vertical temperature gradients as high as 3° C were
measured over closed plant canopies. Temperatures are expected to be
highest near the canopy surface (just below the mean canopy surface
level), decreasing above and below this plane. Soil temperatures
(measured at 5-cm depths) were often 4° C or more lower than air
temperatures above the canopy. Temperatures of rapidly transpiring
leaves were typically ca. 1° C less than surrounding air temperatures.
During gusty periods (wind gust above 0.5-1.5 m sec"-'-), air entering
the chambers from the top reduced temperature gradients within the
chambers to more nearly the ambient wind temperatures.
Pollutant Concentrations;
Oxidant concentrations were essentially the same in nonfiltered
chambers and the ambient air. Filtered air chambers showed an average
reduction of about 50% in the oxidant levels (averaged over the
chambers at the 1/2- to 1-m height) during a moderately breezy day.
Oxidant concentrations within the chambers ranged from ca. 1 pphm to
4.1 pphm during a period when ambient levels were 5.2 pphm. The
concentrations above 1 pphm were due to gusts of air bringing oxidants
into the chambers. The chamber air filters allowed oxidant concen-
trations of 1 pphm to pass through (i.e., they were about 80%
efficient in cleansing oxidants from the air entering through the
chamber blower system).
Soil Moisture:
Soil moisture measurements made with soil moisture blocks showed
that soils in the southern parts of the chambers typically contained
more moisture than did soil in the northern parts. Two possible
factors may have contributed to this: (1) the southern parts of the
chambers may have received more rainfall due to "rainshadows" caused
by the average angle by which rainfall entered the chambers, and
(2) light shadows cast across the southern parts during high light
conditions may have reduced transpiration rates of shaded plants.
Also, soil moisture was higher in soils where soybean plants were
senescing than in soil where plants were actively growing. Lower
transpiration rates of senescing plants caused less depletion of the
soil moisture.
37
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/3-77-128
3. RECIPIENT'S ACCESSIOI*NO.
4. TITLE AND SUBTITLE
The Effects of Oxidant Air Pollutants on Soybeans,
Snap Beans and Potatoes
5. REPORT DATE
November 1977
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
H.E. Heggestad, R.K. Howell and J.H. Bennett
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Plant Stress Laboratory, Plant Physiology Institute,
Northeastern Region, Agricultural Research Service,
U.S. Dept. of Agriculture, Beltsville, Maryland 20705
10. PROGRAM ELEMENT NO.
1AA602
11. CONTRACT/GRANT NO.
IAG-D6-0479-1
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Corvallis Environmental Research Laboratory
orvallis, Oregon 97330
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/02
15. SUPPLEMENTARY NOTES
.16. ABSTRACT
During the past 5 years the impact of photochemical oxidants on soybeans and snap
beans in Maryland and on potatoes in Virginia and Delaware was assessed with open-top
chambers. Experiments with soybeans were conducted at Queenstown, MD from 197J-1975,
The mean yields of four selected soybean varieties grown in open-top chambers with
carbon-filtered air and in plots without chambers were about the same. However, the
mean yields of beans grown in chambers with nonfiltered air were significantly lower
(about 20%). In experiments with snap beans at Beltsville, MD from 1972-1974, the bean
yield from one of three varieties tested was decreased 14% by oxidants, whereas the
other two varieties did not show a yield decrease. Snap beans grown in plots without
chambers produced about the same as those in chambers with nonfiltered air. Results
from snap bean experiments conducted in 1975 and 1976 using the circular plot design
and four varieties were similar to those obtained in the first 3 years of study using
row plots.
At Painter, VA, in 1975, three of four potato varieties showed a significant yield re-
duction (average 30%) in chambers with nonfiltered air as compared with filtered air.
The variety Pungo yielded the same in the two different chamber environments. Mean
yields for these potato varieties were about the same when grown in the plots without
chambers as when grown in filtered-air chambers, but were significantly lower when grow i
in unfiltered chambers. However, mean yields of potatoes were not significantly differ
ent in these three environments in an experiment at Georgetown, Delaware in 197o.
In 1975, mean hourly oxidant concentrations were higher at Painter, VA than at
Beltsville, MD but peak values were higher at Beltsville.
In 1976, a clear plastic tunnel-type chamber tested at Beltsville proved to be suit-
able for assessing air pollution impact on snap beans. The primary advantage over open
top chambers was lower oxidants in the tunnel chamber with filtered air.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a.
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Plant Effects
Photochemical Oxidants
Soybeans
Snap beans
Potatoes
Yields
open-top chambers
tunnel-type chambers
02/D
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
49
20. SECURITY CLASS (Thispage)
Unclas sified
22. PRICE
EPA Form 2220-1 (9-73)
Jj-GPO 799-521
38
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