TOBACCO,
A SENSITIVE MONITOR
FOR PHOTOCHEMICAL
AIR POLLUTION
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Heollh Service
Consumer Protection and Environmental Health Service
-------
TOBACCO, A SENSITIVE MONITOR
FOR
PHOTOCHEMICAL AIR POLLUTION
by
Walter W. Heck
Frank L. Fox
C. Stafford Brandt
and
John A. Dunning
Agricultural Section
Division of Economic Effects Research
U. S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Consumer Protection and Environmental Health Service
National Air Pollution Control Administration
Cincinnati, Ohio
June 1969
-------
Dr. Walter W. Heck and Dr. C. Stafford Brandt are employees of the U.S.
Department of Agriculture, but are assigned to the Division of Economic
Effects Research of the National Air Pollution Control Administration.
The AP series of reports is issued by the National Air Pollution Control
Administration to report the results of scientific and engineering studies,
and information of general interest in the field of air pollution. Information
reported in this series includes coverage of NAPCA intramural activities
and of cooperative studies conducted in conjunction with state and local
agencies, research institutes, and industrial organizations. Copies of AP
reports may be obtained upon request, as supplies permit, from the Office
of Technical Information and Publications, National Air Pollution Control
Administration, U. S. Department of Health, Education, and Welfare,
Ballston Center Tower No. 2, 801 North Randolph Street, Arlington,
Virginia 22203.
National Air Pollution Control Administration Publication No. AP-bs
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CONTENTS
ABSTRACT iv
INTRODUCTION 1
PILOT STUDY I 3
PILOT STUDY II 7
Soil and Nutrient Combination-1 7
Soil and Nutrient Combination-2 ... 8
Growth Interactions 9
Shading Interactions . . 10
First Summer Monitoring Program 10
Second Summer Monitoring Program 11
DISCUSSION 15
APPENDIX. TOBACCO MONITORING PROGRAM PROCEDURE ... 17
REFERENCES 23
iii
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ABSTRACT
The development of a technique by which the sensitive tobacco variety,
Bel W3 is used as a monitor for photochemical air pollution is discussed.
The technique uses the plant as an indicator of the oxidant complex in both
urban and rural areas. Two pilot studies that were conducted over a 3-year
period during the development of the monitoring technique are included in the
discussion. Attention is given to an explanation of the proper procedures for
planting, transplanting, fertilizing, and caring for mature plants. The
methods used in determining and recording injury to plant leaves is included;
the studies showed almost daily injury to monitoring plants.
KEY WORDS: tobacco, monitor, photochemical, oxidant, plant, and air
pollution
iv
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TOBACCO, A SENSITIVE MONITOR
FOR
PHOTOCHEMICAL AIR POLLUTION
INTRODUCTION
Indigenous vegetation has been used to identify the photochemical com-
plex, to help map the extent of photochemical pollution, and to provide some
evidence in support of control programs. The use of natural vegetation as a
pollution monitor, however, is limited by variations in sensitivity because of
differences in naturally occurring cultural and environmental conditions, non-
specificity in injury symptoms because of poor care of plants, and lack of
uniform distribution of species within a. monitoring area.
Various attempts have been made to assess naturally occurring pollu-
tion loads and to identify specific "smog" components by special planting of
a specific variety of plant under more or less controlled conditions. The
most comprehensive program of this type was attempted in Los Angeles with
annual bluegrass and petunia as the monitoring species. ^ in a similar pro-
gram, pinto bean plants were used. 3 The monitoring plants were grown under
controlled conditions in both studies and exposed to ambient conditions for a
24-hour period. Attempts to correlate injury with oxidant level were only
partially successful. MacDowall et al. 4 correlate sensitivity of tobacco with
oxidant level by using an empirical factor (the coefficient of evaporation).
This factor was developed from several meteorological factors and has been
used with some success in forecasting oxidant injury to tobacco.
At present no technique that combines ease of use and relatively uniform
sensitivity of plant material over a long period of time has been developed for
use by an inexperienced operator. The development of such a technique
employing Bel W3 tobacco is discussed herein.
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PILOT STUDY I
Air pollution problems that relate to greenhouse management prompted
a study to determine the utility of tobacco as a monitor of ambient oxidant.
Tobacco is excellent for this type of study for several reasons: It has been
more intensively studied than any other photochemically sensitive species;
it has an indeterminate growth habit during vegetative stages; mature leaves
are most sensitive and show fairly uniform sensitivity at a given stage of
growth; new injury is readily separated from old injury; it can be grown under
uniform cultural conditions with a minimum of care; a highly susceptible
variety, Bel W3, has been developed;^ its symptoms of oxidant injury are
characteristic, easily identifiable, and quite specific. Figures 1 and 2 show
characteristic oxidant (ozone) fleck on Bel W3 tobacco.
Figure 1. Character! sti c oxidant (ozone) injury to
Bel W3 tobacco variety showing complete
destruction of older leaves.
Figure 2- Single tobacco leaf shows 20 to 25 percent
Injury from oxidant (ozone) fleck.
A pilot study was conducted in the metropolitan areas of Boston, Cin-
cinnati, and St. Louis during the summer months to determine whether Bel
W3 tobacco could be used as a simple field monitor and to answer three basic
questions:
1. Are oxidant concentrations in metropolitan areas, which presum-
ably are from photochemical sources, sufficient to produce mark-
ings on the leaves of sensitive vegetation?
2. Can estimates of the frequency of injury be obtained?
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3. Can a quantitative estimate of injury be related to concentration or
dose of oxidant?
Fifty-five greenhouse operators in the three metropolitan areas agreed
to participate in the study. Each grower was asked to situate two tobacco
plants inside his greenhouse. He was to provide at least a bushel of his
normal potting soil, water the plants as needed, and follow his standard dis-
ease control and fertilizer practices. Each grower was instructed in the
identification of the symptoms of oxidant injury to the tobacco and was
requested to examine the plants daily and record new injury by both leaf and
plant number. Cincinnati locations were inspected every 2 weeks by a
National Air Pollution Control Administration staff member, and detailed per-
centage injury indices were obtained.
Detailed data obtained from the growers in the three metropolitan areas
cannot be reported because of the variability in cultural conditions and care
of plants and because of the irregularity and doubtful reliability of observa-
tions by the greenhouse personnel. Thus, that the sensitivity of exposed
material throughout the area was the same or that results noted were uni-
formly recorded is not known. As a result, no estimates can be made in
regard to the regional distribution of any one episode of oxidant injury nor
can estimates of differences in severity among episodes be made. From the
data obtained, however, some conclusions can be drawn. On some occasions
during the season, oxidant concentrations were sufficiently high to cause
markings on sensitive vegetation. All locations were subject to episodes of
elevated oxidant concentration sufficient to mark sensitive vegetation. There
appeared to be some correlation between the occurrence of high oxidant con-
centrations at the Continuous Air Monitoring Program Stations and reports
of tobacco injury within the next 3 days in both Boston and St. Louis. Some
of the growers correlated appearance of tobacco injury with appearance of
similar injury patterns on other greenhouse crops. However, the use of
observers and different cultural conditions in this type of study is of only
limited value.
The sensitive variety of tobacco used in the study offers communities
a method of detecting the presence of phytotoxic concentrations of oxidant
and provides a method for determining the frequency of occurrence and gen-
eral estimates of regional distribution and level of oxidant. However, greater
control over cultural conditions, exposure, and collection of data must be
exercised.
Results of the biweekly inspection of the Cincinnati plants are summa-
rized for the period from July 7 through September 9. Injury as a. percentage
value for each leaf was determined and reported on the basis of total plant
injury (average of two plants). Possible environmental factors that affect
sensitivity were obtained and are included with the injury indices in Table 1.
Results suggest that evaporative cooling has had the greatest effect on sensi-
tizing plants to ambient oxidant. This correlates with lower maximum
greenhouse temperatures and is probably a moisture stress effect. No evi-
dence of correlations between sensitivity and fertilizer schedule, and distance
and direction from town was found. However, correlation of shade, soil
texture, type of house, and care of plants was noted. Thus growth and expo-
sure conditions are important to such a. study. Results suggest no significant
difference in oxidant concentrations within an 8- to 14-mile radius of the
center of Cincinnati.
TOBACCO, A SENSITIVE MONITOR
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Table I. INTERACTION OF FACTORS ON RESPONSE OF TOBACCO
TO OXIDANT POLLUTION IN METROPOLITAN CINCINNATI
Environmental factors
Average injury index
Temperature
Evaporative cooling 95°F
Fan only 105°F
No cool ing 1 15°F
Soil texture
Light
Medium
Heavy
Type of house
Florist
Vegetable
Care of planets
Good
Med i um
Poor
Fertilizer schedule
None
1-8 appl ications
10 or more apol ications
Shade, percent
0-10
15-45
above 50
Distance from center of town
7 mi les or less
7 to 13-1/2 miles
Direction from town
W-NW
N-NE
SE
Number of
locations
2k
6
2
16
8
9
7
16
8
11
8
9
8
12
4
10
10
4
14
10
11
12
1
Injury index3
545 (0-1820)
1200
565
300
645
630
320
700
230
895
425
175
410
625
590
365
630
790
520
580
595
475
840
Values are reported as percent cumulative leaf injury per plant.
Each plant value is obtained by adding the individual injury
percentages from each leaf.
Factors affecting tobacco sensitivity were determined from the study
and separated into controllable and non-controllable variables (Table 2).
These factors were considered when setting up the second study.
Pilot Study I
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Table 2. FACTORS AFFECTING THE SENSITIVITY OF TOBACCO
TO PHOTOCHEMICAL AIR POLLUTANTS3
Factors
Controllable
Not controllable
Light intensity
Soil structure and
compaction
Nutrient level
Soi1 moisture
Insects and diseases
Light duration
Light quali ty
Temperature
Hum i d i ty
Wind speed
Ambient pollutants
Use a 50 percent shade
cloth so plants are not
exposed to full sunlight
Use a light, friable mix
with high water-holding
capabi1i ties
Use regular fertilizer
with high nitrogen
content
Water daily, the 1ight
soil mix will drain well
and give good aeration
Minimize and schedule
use of controls
Partial reduction of
leaf temperature using
shade cloth
Partial reduction with
shade cloth
Natural
variations
Natural
variations
Natural
variations
Natural
variations
Natural
variations
Natural
variations
Natural
variat ions
Natural
variations
These factors were determined from the first pilot study. They
affect sensitivity during the growth of the plant as well as during
the exposure period.
TOBACCO, A SENSITIVE MONITOR
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PILOT STUDY II
Results of the first study enabled researchers to develop a second study.
Its procedure, modified following its completion, appears in the Appendix.
The second study was designed to answer four questions:
1. What is the best soil mix and nutrient combination to use for maxi-
mum plant sensitivity and good growth?
2. How long is the tobacco sensitive and what growth habit is
preferable?
3. What shade factor should be used?
4. What is the area of influence of the photochemical complex in the
Cincinnati area?
SOIL AND NUTRIENT COMBINATION-1
Three soil types (peat-perlite, peat-perlite-soil, and peat-perlite-
s oil-manure) and four nutrients (Hoagland, Plant Marvel, * Plant Marvel and
Cal-Mag, and tap water) were used in this experimental design. Each nutrient
except tap water was used with each soil type. Tap water was used only with
the peat-perlite-soil-manure soil to give ten soil-nutrient combinations.
Four replicates were used per treatment combination, and the complete set of
ten soil-nutrient combinations was tested seven times during the summer
period, for a total of 28 replications per treatment.
Tobacco was seeded, transplanted after 4 weeks into the different soil
types in 4-inch plastic pots, and grown for 1 week with the appropriate nutri-
ent in a greenhouse in which the air was charcoal filtered. The plants were
then placed outside under a 50 percent shade cloth, and exposed to the ambient
air for 2 weeks. A new experimental replicate was started each week to allow
an overlap. Injury indices were recorded every day for 2 weeks, then the
plants were discarded. Indices for average injury per leaf for each plant
were obtained and used to determine results shown in Table 3. The plants
grown with tap water showed poor growth with obvious nutrient defiency;
and although they were the most sensitive, their poor growth made them poor
monitors for air pollution. Plants grown in the Hoagland nutrient were more
sensitive than those fertilized with Plant Marvel and Plant Marvel plus Cal-
Mag but did not grow as well. Considering health of plants, sensitivity, and
work involved in care and maintenance of monitoring sites, peat-perlite-soil
with a 20-20-20 nutrient addition (this could be the Plant Marvel) is recom-
mended for use with the monitoring plants.
*Mention of company or product name does not constitute endorsement by the
Department of Health, Education, and Welfare.
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Table 3. INTERACTION OF SOIL AND NUTRITION ON RESPONSE
OF TOBACCO TO AMBIENT OXIDANT LEVELSa
Nutrient
Soil Hoagland Plant Marvel
Plant Marvel
Cal-Mag
Tap
Water
Average
Soi 1
Peat-perl i te
(1/1)
Peat-perl i te-
soi 1
(1.5/1.5/1.0)
Peat-perl i te-
soi 1-manure
41
43
43
31
37
37
35
34
35
I 36
38
(54)b 39
Average nutrients
42
35
35
Values are reported as average injury per leaf on a percentage basis for
those leaves showing injury from ambient pollution. All values are
averages of 28 replications. Mean values connected by lines are not
statistically different. Summary shows no difference between the soils,
although there appears to be an interaction between nutrient and soil in
the case of Plant Marvel and peat-perlite. The Plant Marvel and Plant
Marvel plus Cal-Mag are not different from each other, but are different
from the other nutrients. Hoagland and tap water are different in the
peat-perlite-soi1-manure mix.
The value listed for tap water was not included in the average for the
peat-perlite-soil-manure mixture.
SOIL AND NUTRIENT COMBINATION-2
Two soil types (peat-perlite-soil and peanut hulls-soil) and two nutrients
(Kapco and Plant Marvel plus Cal-Mag) were used in this experimental design.
Kapco was used only with the peat-perlite-soil; the second nutrient was used
with both soils. The tobacco was grown with initial transplant as detailed in
the Appendix. The second transplant into bushel baskets was into the experi-
mental soil type with the appropriate nutrient. Each treatment was replicated
12 times in a. randomized block design and was an integral part of the study on
growth effects. Plants were exposed to the ambient air under a 50 percent
shade cloth.
Injury indices were obtained daily (Monday through Friday), and cumula-
tive injury indices for each plant were reported after 4, 8, 12, and 15 weeks.
Mean values (12 replications) for each treatment are reported in Table 4. No
evidence of a nutrient effect was noted. After the first 4-week period signifi-
cantly less injury to plants grown in the peanut hulls-soil mixture than to
those grown in the peat-perlite-soil mixture was noted. This was probably
due to the longer transplant recovery period in the heavier peanut hull-soil
mixture. No other 4-week period showed significant differences, although
the last 3-week period showed greater injury to plants in the heavy mix.
This may have been due to the greater amount of uninjured tissue on the
plants in the heavier soil treatment prior to the last 3-week period. Seasonal
values for the three treatments are the same. The heavier soil is not recom-
mended for monitoring purposes, because severe wilting at transplant results
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in a slower start. The peat-perlite-soil mixture with a 20-20-20 nutrient
addition is recommended.
Table k. EFFECT OF FERTILIZER AND SOIL TYPE ON SENSITIVITY
OF BEL W3 TOBACCO TO AMBIENT POLLUTIONS
Soi 1/ferti 1 izer
Peat-perl i te-soi 1
(1.5/1.5/1.0)
Plant Marvel
20-20-20
Alternate Cal-Mag
Peat-perl i te-soi 1
(1.5/1.5/1.0)
Kapco 20-20-20
Peanut hul 1 s-soi 1
Plant Marvel , 20-20-20
Alternate, Cal-Mag
Cumulative injury indices
7/13
Ct week)
915
870
695b
8/10
(8 week)
1255 (2170)
1285 (2155)
1275 (1970)
9/7
(12 week)
830 (3000)
905 (3060)
865 (2835)
9/28
(15 week)
555 (3555)
515 (3575)
670 (3505)
Values are reported as percent cumulative leaf injury per plant. Each plant
value is obtained by adding the individual injury percentages from each leaf.
Value is statistically different from the other two values listed on 7/13 at
the 0.01 level.
GROWTH INTERACTIONS
Tobacco was chosen as a monitoring plant in part because it produces
new leaf tissue throughout most of the growing season. In conjunction with
the nutrient study, three growth habits were studied for each soil-nutrient
combination for a total of 12 replicates per growth habit. These were grouped
in studying the growth effects, because the soil-nutrient had no effect. One
group of plants grew normally throughout the season producing, after 8 to 10
weeks, tall, rather unwieldy plants that were difficult to handle. A second
group was topped after 8 weeks and the regrowth was studied. A third group
made use of new plants every 4 or 8 weeks. With 12 plants per nutrient
treatment, each growth treatment contained four plants. In the three growth
treatments (one per soil-nutrient combination) in which new plants were used,
the four plants per treatment were started together. Two of the four
plants in one soil-nutrient combination were replaced with young plants after
2 weeks. Two of the four plants in each of the other two soil-nutrient com-
binations were replaced by young plants after 4 weeks. Thereafter, the two
older plants in the first soil-nutrient combination were replaced every 2
weeks and the two older plants in each of the other two combinations were
replaced with young plants every 4 weeks .
Cumulative injury indices were obtained as in the soil-nutrient study
and are reported in Table 5. Because it takes a. week to 10 days for newly
transplanted plants to show maximum sensitivity, the cumulative indices for
the replacement plant series were obtained from only two plants for the 10
days after plants were replaced. Values were not different after the first
10 days. Plants were topped after 8 weeks, and results showed that it took
about 4 weeks for these plants to regain sensitivity. Plants grown during
Pilot Study
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full season and replacement series plants were no different after 12 weeks.
Plants transplanted during September developed slowly and did not produce
as much sensitive tissue. Thus, they show less injury during the last 3-
week period. The regrowth was well started a'fter 4 weeks and contained con-
siderable sensitive tissue during the last 3 weeks. Plants grown full season
were in flower, and all leaves, including the floral bracts, showed injury at
the end of the 15-week exposure period.
Table 5. EFFECT OF GROWTH PERIODS ON TOTAL INJURY TO BEL W3
TOBACCO FROM AMBIENT POLLUTIONS
Growth period
Ful 1 season
4- and 8- week
growth alterna-
ting replacement
every 2 and 4
weeks
Topping after
8 weeks wi th
regrowth
Cumulative injury indices^
7/13
(4 week)
815
840
820
8/10
(8 week)
1285 (2100)
1235 (2075)
1300 (2120)
9/7
(12 week)
915 (3015)
820 (2895)
**190 (2310)
9/28
(15 week)
660 (3675)
--425 (3320)
670 (2980)**
aValues are reported as percent cumulative leaf injury per plant. Each plant
value is obtained by adding the individual injury percentages from each leaf.
Values with asterisks are statistically different from the other two values
listed for the same date at the 0.01 level.
Plants that were allowed to develop for a full season were the most
severely injured; however, the injury was not much greater than that seen in
the replacement series. Because of difficulties inherent in working with
large plants, a replacement sequence of 6 weeks -alternating replacement
of two of the four plants every 3 weeks is recommended in the procedural
outline in the Appendix.
SHADING INTERACTIONS
Four plants were grown as detailed in the Appendix on an 8 to 4 replace-
ment basis with final transplant into bushel baskets under 0, 35, 50, and 80
percent shade. Injury indices "were obtained and reported as in the earlier
studies. Results are given as cumulative average plant values for the paired
plants in the different shade treatments (Table 6). Results suggest that plant
sensitivity is reduced if plants are left in the sun during the mid-summer
months, possibly because of higher temperatures, light intensity, and drought
conditions, all of which may cause soil moisture stress. A 50 percent shade
cloth is recommended for all monitoring work to protect the plants.
FIRST SUMMER MONITORING PROGRAM
Plants were grown as detailed in the Appendix on a 4-week alternating
replacement basis at seven locations in the vicinity of Cincinnati, Ohio.
Cumulative leaf injury on a percent basis for each plant was obtained on a
weekly basis at each location. Continuous oxidant readings were recorded at
10
TOBACCO, A SENSITIVE MONITOR
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Table 6. EFFECT OF SHADE ON SENSITIVITY OF TOBACCO BEL W3
TO AMBIENT OX IDANT LEVELS3
Date
replaced
7/06/66
8/03/66
8/31/66
9/28/66
Length of
exposure,
weeks
it
8
8
8
Plants
(pai red)
odd
even
odd
even
Cumulative injury indices,
percent shade
0
1)90
1500
1658
1313
35
1673
1280
50
615
1902
1553
1295
80
608
2070
1680
1293
Values are reported as percent cumulative leaf injury per plant. Each plant
value is obtained by adding the individual injury percentages from each leaf.
Definite reductions are noted with the 7/6 and 8/3 comparisons between 0
shade and both the 50 and 80 percent shades. These are somewhat tenuous
because only two plants were used for each data point.
the laboratory (Mast) and corrected to 2 percent neutral KI values. The
weekly oxidant index was recorded as the cummulation of hourly averages
that exceeded 3. 0 parts per hundred million (pphm) of oxidant during the hours
between 6 a.m. and 10 p.m. All hourly averages from the time the oxidant
level reached 3. 0 pphm were included through the last one above 3. 0, even
if some of the mid values fell below 3. 0. The total was then arbitrarily
divided by 2 to obtain the final index. Plants were lost at two locations from
high winds. Although the recorded oxidant injury -was similar to injury to
plants at the other five locations, data from the two locations are not included
in the summary table. Table 7 includes the weekly oxidant index, the weekly
plant injury index for the major study (Tables 4 and 5), and the weekly plant
injury index for five of the monitoring sites. Distance and direction from the
center of Cincinnati are included as well as the season's total cumulative
indices. The injury index to oxidant index ratio was determined for the two
groups of plants located at the oxidant monitoring site.
No consistent relationship between oxidant values and plant injury was
found. Meteorological factors were not included in this study. Possibly an
inclusion of these would produce a correlation between oxidant and injury.
The levels of sulfur dioxide and nitrogen dioxide would be of interest in view
of the reported synergism between sulfur dioxide and both ozone and nitrogen
dioxide. The data suggest that within the limits of the study there is little
difference in the phytotoxic potential of the pollution complex at any location
monitored. There is a. suggestion that at certain times one station has a
higher phytotoxic potential or that meteorological conditions are such that
plants show variable sensitivity at the five locations. Injury to the two groups
of plants at the laboratory was remarkably uniform.
SECOND SUMMER MONITORING PROGRAM
Plants were grown as detailed in the Appendix on a 3-week alternating
replacement basis at five locations east of Cincinnati, Ohio. Stations were
located at 5, 7, 25, 50, and 75 miles east of the center of the city. Injury
indices and oxidant indices were generated as outlined, and results are shown
in Table 8.
Pilot Study II
11
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Table 7. RESULTS OF FIRST CINCINNATI AREA SUMMER MONITORING PROGRAM3
Location
Oxidant
(laboratory)13
Laboratory - 1
(Tables 4 and
5)
Laboratory - 2
(Mon i tor s i te)
Dunning
Matthis
Clark
Ross
Distance (miles)
and d i rect i on
from Cincinnati
5(E)
5(E)
5(E)
18(E-NE)
25(E)
30(NE)
30(SE)
Ratio:
Injury Laboratory - 1
ox i dant
Laboratory - 2
Weekly accumulated plant injury or oxidant indices
6/17
140
10
10
65
20
50
15
0.06
0.06
6/24
240
90
180
330
190
300
190
0.38
0.74
7/1
280
225
175
80
200
200
205
0.81
0.74
7/8
230
310
350
200
260
255
130
1.33
1.52
7/15
215
270
300
270
295
305
310
1.26
1.38
7/22
195
400
340
235
290
250
250
2.06
1.77
7/29
220
290
255
260
235
225
200
1.31
1.16
8/5
295
200
100
100
165
245
255
0.69
0.34
8/12
255
250
245
120
165
190
105
0.97
0.97
8/19
165
255
330
305
270
325
225
1.58
2.04
8/26
100
190
190
235
160
85
175
1 .92
1 .89
9/2
195
125
125
190
175
175
255
0.66
0.66
9/9
125
190
130
55
200
110
195
1.53
1 .04
Total
2655
2805
2730
2445
2625
2715
2510
1 .06
1.03
o
CO
>
o
o
o
O
Values are reported as average percent cumulative new leaf injury per plant (average of four plants).. Each,plant value'is
obtained by adding the injury percentages from each leaf. Differences, which might be due to area distribution of oxidant
and/or to localized meteorological conditions, do occur among locations.
The oxidant index is the accumulation of hourly averages that exceed 3.0 pphm of oxidant (Kl) during the hours 6 a.m. to
10 p.m. When the oxidant level increases to 3-0 pphm, all hourly averages are Included through the last one above 3.0 pphm,
even if some of the middle values fall below 3.0 pphm. The total is then divided by 2 to obtain the oxidant index.
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Table 8. RESULTS OF SECOND CINCINNATI AREA SUMMER MONITORING PROGRAM3
Location
Oxidant
(laboratory)13
Laboratory
Benken
Matthis
Garrison
Shoemaker
Distance (miles)
and direction
from Cincinnati
5(E)
5(E)
7(NE)
25(E)
50(E)
75(E)
Ratio:
Injury , .
OxTdaTt Laboratory
Weekly accumulated plant injury or oxidant indices
6/13
310
10
40
15
10
0
0.03
6/20
200
60
125
65
65
25
0.30
6/27
90
50
200
130
240
85
0.56
7/5
35
200
185
215
230
285
5.70
7/12
110
85
110
340
255
125
0.77
7/19
40
230
120
80
115
260
5.80
7/26
80
95
75
80
65
225
1.19
8/2
210
270
255
265
205
140
1 .29
8/9
170
290
260
225
255
270
1.71
8/16
135
180
240
205
75
205
1.33
8/23
150
110
160
140
75
55
0.74
8/30
95
200
80
115
120
120
2.10
9/5
110
175
135
280
140
230
1.59
Total
1735
1955
1985
2155
1850
2025
1.13
Values are reported as average percent cumulative new leaf injury per plant (average of four plants). Each plant value is
obtained by adding the injury percentages from each leaf. Differences, which might be due to area distribution of oxidant
and/or localized meteorological conditions, do occur among locations.
The oxidant index is the accumulation of hourly averages that exceed 3.0 pphm of oxidant (Kl) during the hours 6 a.m. to
10 p.m. When the oxidant level increases to 3.0 pphm, all hourly averages are included through the last one above 3-0 pphm,
even if some of the middle values fall below 3.0 pphm. The total is then divided by 2 to obtain the oxidant index.
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No consistent relationship between oxidant values and plant injury was
found during the 1967 monitoring season. The data suggest that within the
limits of the study little difference exists in the phytotoxic potential of the
pollution complex with distance from Cincinnati. During any given week
there are real differences in amount of injury among sites. It is suggested
that Cincinnati is not the major source of pollution for the two distant sites
and may have relatively little effect on the site farthest from the city. How-
ever, no area of southeastern Ohio is free of phytotoxic oxidant pollution.
Considerable new injury was recorded during each week of the test period.
14
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DISCUSSION
The technique for a relatively simple plant monitoring system for the
photochemical complex has been developed. The system employs the sensi-
tivity of Bel W3 variety tobacco grown under controlled soil conditions and
50 percent shade. Methodology was worked out and duplicated over two
seasons of actual exposures. Although correlations with oxidant levels are
poor, the injury resembles ozone injury to tobacco under controlled exposures
and the field injury is associated with the photochemical complex.
Results presented in this paper suggest that the impact of the photo-
chemical complex is not just an urban problem but is a problem in rural
areas as well. Probably all areas east of the Mississippi have sufficient
photochemical pollution to produce injury to sensitive plants at certain times
during their development.
The use of this monitoring system would give a community estimates
of the frequency of the occurrence of phytotoxic levels of oxidants, an esti-
mate of severity of each fumigation, and some estimate of areal distribution
of phytotoxic potency in both time and space.
15
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APPENDIX
TOBACCO MONITORING PROGRAM PROCEDURE
I. Plants
A. Tobacco
1. Scientific name - Nicotiana tabacum, L.
2. Variety Bel W3 (from Dr. H. E. Heggestad, USDA, Beltsville,
Maryland).
B. Culture
1. Seedlings and transplants must be grown in an enclosure in which
the air is charcoal filtered.
2. Seeding
a. Fill a 4-inch pot with vermiculite and wet the vermiculite.
b. Spread 30 to 50 seeds over the top of the vermiculite. This
will yield about 30 good seedlings per pot.
c. Place pot in a saucer.
d. A special growth chamber in which temperature can be regula-
ted (70°F night temperature and 80°F day temperature) and
day length can be regulated (8-hour day with a light intensity
of 2000 ft-c) is recommended for growing seedlings.
e. Water seedlings pot from the bottom (in the saucer) with 1/2-
strength nutrient (see III) until after emergence.
f. After emergence, seedlings can be watered from the top with
1/2-strength nutrient.
3. Trans planting
a.. When plants are 25 to 30 days old, transplant into individual
4-inch pots in a peat-perlite mix (see II-A).
(1) Separate plants carefully, allowing some vermiculite to
remain on the roots.
(2) Hold the plant by the stalk in the center of an empty 4-inch
pot and add the peat-perlite mix. The mix should be
packed gently to provide good contact with roots. The mix
should be added to within 1/4-inch from the top of the pot
and the plant held at a height so that the leaves are exposed
to the air.
(3) Wash mix from the leaves with distilled or deionized water.
(4) Soak each pot with full-strength nutrient (100 150 cm3)
immediately after transplanting.
(5) Place pots into trays to which full strength nutrient is
17
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added. The trays should be washed thoroughly at least
once a week to control algae growth and be refilled with
full-strength nutrient. Distilled or deionized water can
be added to trays when needed.
(6) These transplants are grown in the greenhouse where the
temperature is 80° to 95 °F during the day and 70 °F at
night.
(7) After the seedlings have been transplanted into individual
pots and have three good-sized leaves (about 2 weeks after
transplanting), remove any lower leaves less than 5 inches
in length (measured from the stalk to the tip of the leaf).
b. At this stage of growth (at least 3 good-sized leaves), trans-
plant the tobacco into bushel baskets.
(1) Fill the baskets to approximately 2 inches from the top
with the peat-perlite-soil mix (see II-B).
(2) Remove plant with the peat-perlite mix from the 4-inch
pot and place it into a hole made in the soil. Pack the
soil firmly around the plant and moisten the soil in the
basket with 2 gallons of 20-20-20 fertilizer solution (see
I-B-5-a (2).
4. Use four plants per location.
a. After the first 4 plants have been in baskets for 3 weeks,
replace two of them.
b. Thereafter, every 3 weeks replace the two oldest plants.
5. Daily care
a. Recommended watering schedule
(1) Every other week with Cal-Mag Special.
(a) Mix 1 tablespoon of the fertilizer per 2 gallons of
•water.
(b) Water each plant with 2 gallons of the solution.
(2) Alternate 20-20-20 with Cal-Mag every other week.
(a) Mix 1 tablespoon of the fertilizer per 2 gallons of
water.
(b) Water each plant with 2 gallons of the solution.
(3) Water plants with tap water at least twice a week in addi-
tion to the nutrient. Soak soil until water comes out base
of the basket (2 gallons).
(a) Soil must be kept moist at all times or tobacco will
lose sensitivity.
(b) Peat mulch may be used to help keep the soil moist.
18 TOBACCO, A SENSITIVE MONITOR
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b. Disease and insect control
(1) There is a need for a general spray program for insect
control.
(a) Chlordane sprayed in the basket area (not on the plant)
will offer some help.
(b) Plants may be sprayed with Isotox and Malathion
(each mixed at the rate of 1 tablespoon per gallon of
tap water) whenever insects appear, or on a regular
schedule.
(c) A systemic insecticide may be used in place of the
spray. Add every month.
(2) If a plant becomes diseased, discard plant and basket.
II. Soil
A. Peat-perlite-mixture
1. Materials needed
a. Peat moss
b. Perlite
c. Lime (superfine limestone) and CaSO4 or gypsum
d. Distilled or deionized water
e. 10-quart pail
f. Small cement mixer preferred method of mixing
2. Procedure mix in cement mixer
a. 2 pails (10 qts. each) of peat moss (level full)
b. 2 pails (10 qts. each) of perlite (level full). To each pail of
perlite add 2000 cm^ of distilled or deionized water until all
perlite is wet. This equals 4000 cm^ per mix.
c. When the peat moss and perlite are well mixed (approximately
5 minutes) add: 72 grams lime and 48 grams CaSO4 or gypsum.
Add slowly by hand (tends to stick to sides of mixer).
d. Mix for 20 to 30 minutes, stopping mixer two or three times to
break up lumps.
e. Let mix age for 2 weeks and check pH. Mix pH should be
between 5. 5 and 6. 0. If pH is below 5. 2 remix using another
72 grams of lime. This should bring the pH to above 5.5.
B. Peat-perlite-soil mixture for bushel baskets
1. Use three parts peat-perlite with one part top soil.
2. Rich loam soil is recommended.
3. Mixing is done in cement mixer following the same general
Appendix 19
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outline as listed for mixing the peat-perlite but with no water or
mineral additions. The pH should be between 5. 5 and 6. 5.
III. Nutrient solution (Hoagland's) for plants in 4-inch pots. All of the chemi
cals needed for making the nutrient should be mixed with distilled or
deionized water to form concentrated solutions. From these concentra-
ted solutions, use the required amounts needed to make the nutrient.
Technical grade KNOs, Ca(NC>3)2. 4H2O), MgSO4. 7H2O, KH2PO4, and
K2HPO4 is sufficient.
Chemical
KNO3
Ca(N03)2
MgSO4. 7H2O
KH2P04
K2HP04
Fe chelate
Solution B
{Minor elements)
Grams per liter of
concentrated
solution
101
200
246
lOZjMix these two to
/•form one concen-
43
/tration
cm^ of concentrate
per liter of water
(for nutrient solution)
0. 05 gm
Grams per liter of
concentrated
s olution
2
1
0
0
87
80
22
08
These form
one concen-
trated
solution
cm^ of concentrate
per liter of water
Chemical
H3B03
MnCl2.4H2O
ZnSO4. 7H2O
CuSO4. 5H2O
1/2-strength nutrient equal parts of distilled or
deionized water and full-strength nutrient solution.
IV. Enclosure frame for housing 4 plants
A. 8 by 4 by 6 feet high
B. Recommended construction
1. Use 1- by 4-inch lumber
2. If the program is to continue for one year, redwood should be
used.
3. Brace corners with metal braces and bolts.
4. Frame should be well anchored.
C. Shading
1. North side open - all other sides covered with shade cloth
2. 50 percent shade needed
20
TOBACCO, A SENSITIVE MONITOR
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3. Shade material
a. Saran shade material of 52 percent calculated shade recom-
mended.
b. Comparable material may be substituted for the saran.
4. Location
a. Open area - no natural shade south exposure on hills
b. Have access to water
c. Protect from possible vandalism
d. Plants must be arranged in the enclosure so all have same
exposure.
V. Injury indices
A. Reading
1. All plants should be read weekly, daily, or on some regular
schedule.
2. The same individual should do all the reading.
3. The percentage of injury on each leaf of each plant should be
determined. This is a subjective measure.
B. Summary
1. The percentage of area injured on each leaf is totaled for each
plant at every reading.
2. New injury on each plant for any given period is determined by
the difference in cumulative readings between the beginning and
end of the periods.
3. Site averages are obtained by summing the four plant values and
dividing by four.
Appendix 21
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REFERENCES
1. Heck, W. W. , The use of plants as indicators of air pollution, Int. J. Air
and Water Poll., 1_0:99-111 (1966).
2. Noble, W. M.and L. A. Wright, A bio-assay approach to the study of air
pollution, Agron. J. , 50^:551-553 (1958).
3. Middleton, J. T. and A. O. Paulus, The identification and distribution of
air pollutants through plant response, Arch. Ind. Health, 14:526-532
(1956).
4. MacDowall, F. D. H. , E. I. Mukammal, and A. F. W. Cole, Direct
correlation of air-polluting ozone and tobacco weather fleck, Can. J.
Plant Sci. , 44:410-417 (1964).
5. Heggestad, H. E. and H. A. Menser, Leaf spot-sensitive tobacco strain
Bel W3, a biological indicator of the air pollutant ozone, Phytopathology,
52:735 (1962).
23
GOVERNMENT PRINTING OFFICE : 1969 O - 353=080
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