@article{burkey_miller_fiscus_2005, title={Assessment of ambient ozone effects on vegetation using snap bean as a bioindicator species}, volume={34}, ISSN={["0047-2425"]}, DOI={10.2134/jeq2004.0008}, abstractNote={ABSTRACT}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Burkey, KO and Miller, JE and Fiscus, EL}, year={2005}, pages={1081–1086} }
 @article{booker_miller_fiscus_pursley_stefanski_2005, title={Comparative responses of container- versus ground-grown soybean to elevated carbon dioxide and ozone}, volume={45}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2004.0198}, abstractNote={In studies of CO2–enrichment effects on plants, the applicability of results derived from experiments using container‐grown plants for predictions of future crop performance in a CO2–enriched atmosphere has been questioned. Concerns also have been expressed about plant growth studies with the air pollutant O3 in pot‐grown plants. Further, since elevated CO2 and O3 co‐occur, studies are required with the combination of gases. In this 2‐yr experiment, soybean [Glycine max (L.) Merr.] plants grown in large pots (15 and 21 L) and in the ground were exposed to mixtures of CO2 and O3 in open‐top chambers. The CO2 treatments were ambient and CO2 enrichment of approximately 337 μmol mol−1 added 24 h d−1 Ozone treatments were charcoal‐filtered (CF) air (23 nmol mol−1) and approximately 1.5 times ambient O3 levels (71 nmol mol−1) given 12 h d−1 Relative effects of elevated CO2 and O3 on aboveground biomass and seed yield were quite similar for plants grown in pots compared with plants grown in the ground. Elevated CO2 increased total seed mass and O3 suppressed it to similar magnitudes in both rooting environments. Elevated CO2 also reduced the toxic effects of O3 Net photosynthesis (A) was similar while stomatal conductance (gs) was higher in pot‐grown compared with ground‐grown plants, possibly due to better soil moisture status. The results indicated that planting density and rooting environment affected plant morphology, but relative responses of seed yield to elevated CO2 and O3 were not fundamentally different between soybean plants grown in large pots and in the ground in open‐top chambers.}, number={3}, journal={CROP SCIENCE}, author={Booker, FL and Miller, JE and Fiscus, EL and Pursley, WA and Stefanski, LA}, year={2005}, pages={883–895} }
 @article{heagle_miller_pursley_2003, title={Growth and yield responses of potato to mixtures of carbon dioxide and ozone}, volume={32}, ISSN={["0047-2425"]}, DOI={10.2134/jeq2003.1603}, abstractNote={ABSTRACT}, number={5}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Heagle, AS and Miller, JE and Pursley, WA}, year={2003}, pages={1603–1610} }
 @article{heagle_miller_burkey_eason_pursley_2002, title={Growth and yield responses of snap bean to mixtures of carbon dioxide and ozone}, volume={31}, ISSN={["1537-2537"]}, DOI={10.2134/jeq2002.2008}, abstractNote={ABSTRACT}, number={6}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Heagle, AS and Miller, JE and Burkey, KO and Eason, G and Pursley, WA}, year={2002}, pages={2008–2014} }
 @article{heagle_miller_pursley_2000, title={Growth and yield responses of winter wheat to mixtures of ozone and carbon dioxide}, volume={40}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci2000.4061656x}, abstractNote={Ozone (O3) in the troposphere can cause plant stress, whereas elevated CO2 generally enhances plant growth. Until recently, few studies have considered whether O3 can affect plant response to CO2 or vice versa. We examined these possibilities for soft red winter wheat (Triticum aestivum L.). Plants were grown in 14‐L pots and exposed in open‐top field chambers to all combinations of three CO2 and three O3 treatments. The CO2 treatments were ambient (approximately 380 μL L−1), or ambient with CO2 added for 24 h d−1 to achieve mean concentrations of approximately 540, or 700 μL L−1 The O3 treatments were charcoal‐filtered air (CF), nonfiltered air (NF), or NF with O3 added for 12 h d−1 (NF+). Mean O3 concentrations in the CF, NF, and NF+ treatments were approximately 27, 45, and 90 nL L−1 In the first experiment, eight cultivars with widely different genetic backgrounds were tested. `Coker 9835' was relatively resistant to O3 and `Coker 9904' was relatively sensitive; these cultivars were tested in Exp. 2. Foliar injury caused by O3 was suppressed by elevated CO2 in both experiments. In Exp. 1, plant size and yield increased with CO2 enrichment in the NF and NF+ treatments, but not in the CF treatment. However, the O3 × CO2 interaction was rarely significant. In Exp. 2, growth and yield of C9904 was suppressed more by O3 than was that of C9835. Because of cultivar differences in sensitivity to O3, CO2 enrichment caused greater amelioration of O3 stress and greater enhancement for C9904 than for C9835. Significant cultivar × O3 × CO2 interactions occurred for all growth and yield measures. These results are similar to results with other crops, and further emphasize the need to consider possible interactions between O3 and CO2 when investigating effects of O3 or CO2 on plant systems.}, number={6}, journal={CROP SCIENCE}, author={Heagle, AS and Miller, JE and Pursley, WA}, year={2000}, pages={1656–1664} }
 @article{heagle_booker_miller_pursley_stefanski_1999, title={Influence of daily carbon dioxide exposure duration and root environment on soybean response to elevated carbon dioxide}, volume={28}, ISSN={["0047-2425"]}, DOI={10.2134/jeq1999.00472425002800020034x}, abstractNote={Abstract}, number={2}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Heagle, AS and Booker, FL and Miller, JE and Pursley, WA and Stefanski, LA}, year={1999}, pages={666–675} }
 @article{heagle_miller_booker_pursley_1999, title={Ozone stress, carbon dioxide enrichment, and nitrogen fertility interactions in cotton}, volume={39}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci1999.0011183X003900030021x}, abstractNote={Ozone (O 3 ) in the troposphere can cause plant stress leading to foliar injury and suppressed growth and yield, whereas elevated CO 2 generally enhances growth and yield. Numerous studies have been performed to determine effects of O 3 and CO 2 separately, but relatively few have been performed to determine if 03 can affect plant response to CO 2 or vice versa. Open-top field chambers were used to determine if such interactions occur for cotton (Gossypium hirsutum L.), which is relatively sensitive to O 3 . Nitrogen nutrition is especially important in cotton production so N nutrition was included as an experimental factor. Plants were grown in 14-L pots at low, medium, and high soil N levels and exposed to three CO 2 and two or three 03 treatments in all combinations during two seasons. The CO 2 treatments were ambient (370 μL L -1 ) and two treatments with CO 2 added for 24 h d -1 at approximately 1.5 and 2.0 times ambient. In 1995, the O 3 treatments were charcoal filtered air (CF), and nonfiltered air (NF) with 03 added for 12 h d -1 (NF+). In 1996, a NF treatment was also included to represent ambient 03 conditions. The CF, NF, and NF+ treatments resulted in seasonal 03 concentrations of approximately 23, 51, and 75 nL L -1 . Carbon dioxide enrichment generally stimulated growth and yield whereas 03 exposure suppressed growth and yield. Stimulation induced by CO 2 increased as O 3 stress increased. For example, in 1995 at medium N, the percentage increase in yield caused by doubling CO 2 in CF air was 0%, but was 52% in NF+ air. Comparable values for 1996 were 23% in CF air and 140% in NF+ air. These interactions occurred for a range of soil N levels, and were probably caused by CO 2 -induced prevention of 03 stress. The results emphasize the need to consider O 3 X CO 2 interactions to ensure correct interpretation of cause-effect relationships in CO 2 enrichment studies with crops that are sensitive to O 3 .}, number={3}, journal={CROP SCIENCE}, author={Heagle, AS and Miller, JE and Booker, FL and Pursley, WA}, year={1999}, pages={731–741} }
 @article{heagle_miller_booker_1998, title={Influence of ozone stress on soybean response to carbon dioxide enrichment: I. Foliar properties}, volume={38}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci1998.0011183X003800010020x}, abstractNote={Tropospheric O3 can cause foliar injury, decreased growth, and decreased yield, whereas CO2 enrichment generally causes opposite effects. Little is known about plant response to mixtures of O3 and CO2. Open‐top field chambers were used to determine if foliar responses of soybean [Glycine max (L.) Merr.] to CO2 enrichment are affected by O3 stress and vice versa. Plants were grown in 14‐L pots and exposed to four CO2 and three O3 concentrations in 12 combinations. The CO2 treatments were ambient (366 μL−) and three treatments with CO2 added for 24 h d 1 at approximately 1.3, 1.6, and 2.0 times ambient. The O3 treatments were charcoal‐filtered air (CF), nonfiltered air (NF), and NF with O3 added for 12 h−1 ( NF+), resulting in seasonal concentrations of approximately 20, 46, and 75 nL L−1. Foliar effects of CO2 enrichment were dependent on the amount of stress caused by O3. In the CF treatment, plants were not stressed by O3, and CO2 enrichment caused chlorosis and decreased chlorophyll. In the NF and NF+ treatments, plants were stressed by 03, and CO2 enrichment suppressed chlorosis and increased chlorophyll. Ozone decreased specific leaf weight, increased foliar N and C, and decreased C/N ratios, whereas CO2 caused opposite responses for these measures. Ozone increased foliar S and B but did not affect P or K concentrations. Conversely, CO2 enrichment suppressed foliar S, B, P, and K concentrations. These interactions between O3 and CO2 emphasize a need to consider the amount of plant stress caused by O3 in studies to measure effects of CO2 enrichment.}, number={1}, journal={CROP SCIENCE}, author={Heagle, AS and Miller, JE and Booker, FL}, year={1998}, pages={113–121} }
 @article{miller_heagle_pursley_1998, title={Influence of ozone stress on soybean response to carbon dioxide enrichment: II. Biomass and development}, volume={38}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci1998.0011183X003800010021x}, abstractNote={Previous research has shown that elevated CO2 concentrations can increase plant growth, whereas the air pollutant O3 is phytotoxic. Because elevated concentrations of these gases will co‐occur, the objective of our experiment was to determine if estimates of plant growth response to future levels of CO2 and O3 require experiments to test the gases in combination. Soybean plants [Glycine max (L.) Merr. cv. Essex) were exposed in open‐top chambers to combinations of O3 and CO2 from plant emergence through physiological maturity. Ozone treatments were charcoal‐filtered air (CF), nonfiltered air (NF), and NF with O3 added for 12 d−1 (NF+) (seasonal mean 12 d−1 O3 concentrations of 20, 50, or 79 nL L−1, respectively). Carbon dioxide exposures were for 24 h d−1 giving seasonal mean 12 d−1 concentrations of 370, 482, 599, or 713 μL L−1. Over the season, elevated CO2 usually stimulated growth and O3 suppressed growth. Elevated CO2 usually increased partitioning of biomass to branches, decreased partitioning to pods, increased specific leaf weight, and decreased leaf area ratio. Ozone suppressed leaf and root weight ratios, increased pod weight ratios, and decreased specific leaf weight. Toward the end of the season, both O3 and CO2 accelerated reproductive development. Elevated CO2 moderated suppression of growth by O3, and the highest CO2 concentration completely ameliorated O3 effects on main stem biomass, root biomass, and leaf area. Ozone, however, limited some positive growth responses to CO2, especially at less than a doubling of CO2 concentrations. These results indicate that in order to understand the future impacts of atmospheric gases such as elevated CO2 and O3 on crop growth, their combined effects should be determined.}, number={1}, journal={CROP SCIENCE}, author={Miller, JE and Heagle, AS and Pursley, WA}, year={1998}, pages={122–128} }
 @article{heagle_miller_pursley_1998, title={Influence of ozone stress on soybean response to carbon dioxide enrichment: III. Yield and seed quality}, volume={38}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci1998.0011183X003800010022x}, abstractNote={Ozone in the troposphere can cause plant stress, whereas elevated CO2 generally causes positive responses. Little is known of how these gases interact to affect plant response. Interactive effects on yield and seed quality of soybean [Glycine max (L.) Merr.] grown in 14‐L pots were measured in open‐top field chambers. Essex was tested in 1993, and Essex, Holladay, and NK 6955 were tested in 1994. Plants were exposed from emergence to maturity to four CO2 levels (ambient and 1.3,1.6, and 2.0 times ambient) and three O3 levels (0.4, 0.9, and 1.5 times ambient) in 12 combinations. Increasing O3 suppressed growth and yield, whereas CO2 enrichment stimulated growth and yield. Carbon dioxide‐induced stimulation was greater for plants stressed by O3 than for non stressed plants. For example, CO2 at 2.0 times ambient increased 2‐yr mean seed yield of Essex by 16, 24, and 81% at O2 levels of 0.4, 0.9, and 1.5 times ambient, respectively. Effects of O3 and CO2 on seed oil content were variable with numerous cultivar differences. Seed protein content was never affected. Elevated O3 suppressed oleic acid content in seeds, whereas CO2 increased it; the nature of the O3 × CO2 interaction for oleic acid was similar to that observed for most yield measures. Carbon dioxide‐induced stimulation of plants stressed by O3 was apparently caused partly by amelioration of O3 stress. Interactions between O3 and CO2 must be considered for proper interpretation of cause‐effect relationships in CO2, enrichment studies.}, number={1}, journal={CROP SCIENCE}, author={Heagle, AS and Miller, JE and Pursley, WA}, year={1998}, pages={128–134} }
 @article{booker_miller_1998, title={Phenylpropanoid metabolism and phenolic composition of soybean [Glycine max (L.) Merr.] leaves following exposure to ozone}, volume={49}, ISSN={["1460-2431"]}, DOI={10.1093/jexbot/49.324.1191}, abstractNote={Plants treated with the air pollutant, ozone (O3), often respond with increased transcript levels and activities of enzymes in the general phenylpropanoid and lignin pathways. This suggests that increased biosynthesis of lignin and related products also occurs. The purpose of this study was to determine whether O3 stimulated enzyme activities in these pathways in soybean [Glycine max (L.) Merr.] leaves, and if so, were hydroxycinnamic acids, lignin and suberin also produced. Plants were grown for 6 weeks in charcoal-filtered (CF) air and then treated with either CF air or CF air plus 100 nmol O3 mol−-1 7 h daily for up to 13 d in chambers in the greenhouse or in open-top chambers in the field. In greenhouse experiments, the activities of general phenylpropanoid pathway enzymes (phenylalanine ammonia-lyase and 4-coumarate:CoA ligase) were stimulated by O3 after 6 h. The activity of an enzyme in the lignin pathway (cinnamyl alcohol dehydrogenase) increased in O3-treated plants after 27 h. In greenhouse and field experiments, levels of cell-wall-bound total phenolics, acid-insoluble lignin and lignothioglycolic acid (LTGA) extracted from leaf tissue from O3-treated plants increased on average by 65%. However, histochemistry, UV and IR spectra, radiolabelling and a nitrobenzene oxidation assay all indicated that lignin and suberin did not increase with O3 treatment. Acidinsoluble lignin and LTGA extracted from O3-treated plants probably contained phenolic polymers that form in wounded or senescent tissues, thereby causing overestimates of the changes. Ozone-induced increases in phenolic metabolism, resembling certain elicited defence responses, thus occurred in concert with effects characteristic of the browning reaction and wound responses.}, number={324}, journal={JOURNAL OF EXPERIMENTAL BOTANY}, author={Booker, FL and Miller, JE}, year={1998}, month={Jul}, pages={1191–1202} }
 @article{fiscus_reid_miller_heagle_1997, title={Elevated CO2 reduces O-3 flux and O-3-induced yield losses in soybeans: Possible implications for elevated CO2 studies}, volume={48}, ISSN={["0022-0957"]}, DOI={10.1093/jxb/48.2.307}, abstractNote={Soybeans were grown for three seasons in open-top field chambers to determine (1) whether elevated CO2 (360 versus 700 //mol mol"1) alleviates some of the yield loss due to pollutant 0 3, (2) whether the partial stomatal closure resulting from chronic 03 exposure (charcoal-filtered air versus 1.5 x ambient concentrations) is a cause or result of decreased photosynthesis, and (3) possible implications of C0 2 /0 3 interactions to climate change studies using elevated CO2. Leaf conductance was reduced by elevated C02, regardless of O3 level, or by exposure to 03 alone. As. a result of these effects on conductance, high C0 2 reduced estimated midday 03 flux into the leaf by an average of 50% in charcoal-filtered air and 35% in the high 03 treatment. However, while exposure to O 3 reduced seed yields by 41% at ambient CO2 levels, the yield reduction was completely ameliorated by elevated CO2. The threshold midday 03 flux for yield loss appears to be 20-30 nmol m~2 s" 1 in this study. Although elevated CO2 increased total biomass production, it did not increase seed yields. A/C, curves show a large reduction in the stomatal limitation to photosynthesis due to elevated CO2, but no effect of O3. These data demonstrate that (1) reduced conductance due to O3 is the result, and not the cause, of reduced photosynthesis, (2) 700 //mol mol"' CO2 can completely ameliorate yield losses due to 03 within the limits of these experiments, and (3) some reports of increased yields under elevated CO2 treatments may, at least in part, reflect the amelioration of unrecognized suppression of yield by 03 or other stresses.}, number={307}, journal={JOURNAL OF EXPERIMENTAL BOTANY}, author={Fiscus, EL and Reid, CD and Miller, JE and Heagle, AS}, year={1997}, month={Feb}, pages={307–313} }
 @article{miller_shafer_schoeneberger_pursley_horton_davey_1997, title={Influence of a mycorrhizal fungus and/or rhizobium on growth and biomass partitioning of subterranean clover exposed to ozone}, volume={96}, ISSN={["0049-6979"]}, DOI={10.1023/A:1026496420809}, number={1-4}, journal={WATER AIR AND SOIL POLLUTION}, author={Miller, JE and Shafer, SR and Schoeneberger, MM and Pursley, WA and Horton, SJ and Davey, CB}, year={1997}, month={May}, pages={233–248} }
 @article{booker_reid_brunschonharti_fiscus_miller_1997, title={Photosynthesis and photorespiration in soybean [Glycine max (L.) Merr.] chronically exposed to elevated carbon dioxide and ozone}, volume={48}, ISSN={["0022-0957"]}, DOI={10.1093/jexbot/48.315.1843}, number={315}, journal={JOURNAL OF EXPERIMENTAL BOTANY}, author={Booker, FL and Reid, CD and BrunschonHarti, S and Fiscus, EL and Miller, JE}, year={1997}, month={Oct}, pages={1843–1852} }
 @article{miller_pursley_heagle_1994, title={EFFECTS OF ETHYLENEDIUREA ON SNAP BEAN AT A RANGE OF OZONE CONCENTRATIONS}, volume={23}, ISSN={["0047-2425"]}, DOI={10.2134/jeq1994.00472425002300050033x}, abstractNote={Ethylenediurea (EDU) [N-[2-(2-Oxo-1-imidazolidinyl)ethyl]-N'-phenylurea] often protects plants from visible foliar injury due to the air pollutant O3 , and it has been used to demonstrate yield losses from O3 under field conditions. A few studies, however, have indicated that EDU can suppress plant growth and yield. Because of the potential value of EDU as a research and assessment tool, controlled field experiments with snap bean (Phaseolus vulgaris L. 'BBL-290') were performed to test the effectiveness of different EDU application rates across a range of O3 concentrations. Four O3 concentrations were used in open-top chambers in each of two experiments [charcoal-filtered (CF) air, nonfiltered (NF) air, and nominal O3 additions of 0.025 and 0.05 or 0.03 and 0.06 μL L-1 O3 to NF air]. Ethylenediurea was added biweekly to the potting medium (four applications per experiment) as a soil drench. The EDU treatment concentrations were 0, 14, 28, 56, and 120 and 0, 8, 16, and 32 mg EDU (active) L-1 of potting medium in experiments one and two, respectively. Ethylenediurea provided some protection against O3 -induced foliar injury and growth suppression in both experiments. Measurements of net carbon exchange rate (NCER) and carbohydrate status of the tissues reflected the protective effects of EDU. In the first experiment, however, EDU caused visible foliar injury at some growth stages and suppressed growth. In the second experiment, visible foliar injury was not caused by EDU at any concentration, but pod biomass (yield) was suppressed by EDU in CF chambers. The differences in response to EDU between the experiments may have been due to environmental conditions (i.e., hot and dry during the first experiment and cooler during the second). Ethylenediurea also affected biomass partitioning in the plants grown in CF air (relative biomass was increased in leaves and decreased in pods). The results indicate that although EDU does protect or partially protect snap bean against O3 injury, it may also affect physiology and growth.}, number={5}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={MILLER, JE and PURSLEY, WA and HEAGLE, AS}, year={1994}, pages={1082–1089} }
 @article{miller_booker_fiscus_heagle_pursley_vozzo_heck_1994, title={ULTRAVIOLET-B RADIATION AND OZONE EFFECTS ON GROWTH, YIELD, AND PHOTOSYNTHESIS OF SOYBEAN}, volume={23}, ISSN={["0047-2425"]}, DOI={10.2134/jeq1994.00472425002300010012x}, abstractNote={Abstract}, number={1}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={MILLER, JE and BOOKER, FL and FISCUS, EL and HEAGLE, AS and PURSLEY, WA and VOZZO, SF and HECK, WW}, year={1994}, pages={83–91} }
 @article{miller_heagle_vozzo_philbeck_heck_1989, title={EFFECTS OF OZONE AND WATER-STRESS, SEPARATELY AND IN COMBINATION, ON SOYBEAN YIELD}, volume={18}, ISSN={["0047-2425"]}, DOI={10.2134/jeq1989.00472425001800030016x}, abstractNote={Abstract}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={MILLER, JE and HEAGLE, AS and VOZZO, SF and PHILBECK, RB and HECK, WW}, year={1989}, pages={330–336} }
 @article{miller_patterson_pursley_heagle_heck_1989, title={RESPONSE OF SOLUBLE SUGARS AND STARCH IN FIELD-GROWN COTTON TO OZONE, WATER-STRESS, AND THEIR COMBINATION}, volume={29}, ISSN={["0098-8472"]}, DOI={10.1016/0098-8472(89)90026-9}, abstractNote={Ozone (O3) stress is known to reduce the growth and yield of a number of crops, and water stress can modify the extent of these effects. Both O3 and water stress alter the carbohydrate status of plants. Little is known, however, concerning O3 effects on carbohydrate pools of field-grown plants and whether water stress will modify the carbohydrate response to O3. Cotton (Gossypium hirsutum L. “McNair-235”) plants were exposed to five O3 concentrations in open-top field chambers for 12 hr/day throughout the growing season at two levels of soil water (well-watered or periodically water-stressed). The O3 concentrations ranged from 0.021 to 0.073 μl/l (seasonal mean 12 hr/day concentration). Plants were sampled from each plot on four occasions encompassing the early- to late-reproductive stages of growth. Soluble sugars (glucose, fructose and sucrose) and starch were measured in leaves, stems and roots at each sampling date. Analysis of variance was performed for main effects and interactions of O3 and water treatments at each sampling date (O3 effects were partitioned in linear and quadratic components). Effects of O3 and water stress on soluble carbohydrates and starch were most common in stems and roots. Ozone suppressed carbohydrate concentrations in all cases where significant O3 effects were detected in the absence of O3 × water interactions. On the other hand, soluble carbohydrate concentrations were greater in water-stressed plant tissues when effects were significant and in the absence of interactions. Water-stress effects on starch were variable. Interactions of O3 and water stress were not consistent but often included interaction with the quadratic O3 component.}, number={4}, journal={ENVIRONMENTAL AND EXPERIMENTAL BOTANY}, author={MILLER, JE and PATTERSON, RP and PURSLEY, WA and HEAGLE, AS and HECK, WW}, year={1989}, month={Oct}, pages={477–486} }