Brief Summary of Minutes of Annual Meeting

The NE-1013 Annual Technical Committee Meeting was called to order at 8:15 AM on June 19, 2006 by S. Long (IL) as presiding chair-elect D. Decoteau (PA) was delayed by inclement weather. R. Knighton, the National Program Leader for Air Quality and the NE-1013 CSREES/USDA advisor, remarked that a major concern in Washington was the contribution of agriculture to air quality. He further commented that the emission of ammonia, particulates and animal-produced reactive VOCs in relation to ozone production was an important consideration. Several committee members then noted that the research focus of NE-1013 has been the effects of air quality (ozone) on crop production and the health of native vegetation. Most members expressed concern about continuing in the program if research emphasis shifted to a monitoring/modeling effort from an effects/mitigation effort.

Station reports then began. A. Chappelka (AL) discussed the successful use of ethylenediurea (EDU), an ozone protectorant, to assess effects of ozone on two coneflower species. B. Manning (MA) presented results of EDU effects on seedling and sapling European Ash, which are ozone sensitive. L. Ainsworth (USDA/ARS, Univ. IL) discussed ozone effects on photosynthesis, seed fill and leaf development in Spencer soybean in the SoyFACE experiment. K. Burkey (USDA/ARS NCSU, NC) presented information on ozone tolerance in ancestral soybean germplasm. S. Krupa (MN) discussed progress on the collaborative project of ambient ozone effects on snapbean yield. P. Morgan (USDA/ARS, NCSU) presented results of studies on ozone signaling in Arabidopsis using several mutants defective in signaling pathways. H. Sandermann (Freiburg, Ger.) discussed the toxic agent responsible for ozone foliar injury which is not ozone itself. B. Chevone (VA) presented results of altering leaf ascorbate content on ozone sensitivity in Arabidopsis mutants. C. Bernacchi (IL State Water Survey) discussed leaf-level processes involved in canopy scaling in soybean/corn ecosystems exposed to ozone. D. Decoteau (PA) presented information on the Air Quality Demonstration Center at Penn. State University. This is a major outreach program of NE-1013. V. Wittig (IL) presented a meta-analytical review of the effects of tropospheric ozone on trees. B. Zilinskas (NJ) discussed changes in yield, antioxidant levels and stomatal conductance in wheat under ozone and high CO2 and moisture stress. A. Leakey (IL) presented results on differences in gene expression in soybean exposed to ambient ozone vs 1.25X ambient.

After the station reports, discussion ensued concerning the collaborative effort of the snapbean project. One purpose of the project was to determine the contribution of ambient ozone levels to yield loss of the sensitive cultivar compared to the tolerant one. This information was deemed important to US EPA to consider when setting the ozone standard. The question was raised if the project would really affect the standard setting process since snapbeans are a small component of U.S. agriculture. Additionally, since the resistant and sensitive cultivars do not mature at the same time, the question arose as to the appropriate sampling time. This decision was left to the participating collaborators on the project.

A discussion then began on the renewal of NE-1013. Several areas were mentioned for inclusion in the renewal and the topics/coordinators were natural vegetation/A. Chappelka; water quality/air quality/B. Momen (MD); mechanisms and adaptation/S. Long and K. Burkey; education and outreach/D. Decoteau; and biomonitoring/W. Manning. S. Long was denoted coordinator of the renewal with a draft made available by October 1, 2006. R. Knighton suggested in the future that station reports, either oral or written, should be directed toward specific objectives of the existing proposal.

Potential new members included N. Grulke (USFS, CA), D. Karnosky (Michigan Tech, MI) and John King (NCSU, NC). The meeting site for next year was selected as Rhinelander, WI. D. Decoteau adjourned the meeting at 12N on June 20, 2006.

Objective 1. Describe the spatial - temporal variability of the adverse effects of O3 on crops and forests.

1. Studies investigating the effects of ambient ozone on native forest and wildflower communities growing in the Great Smoky Mountains National Park (GRSM) were completed in 2005. Analysis of tree ring data from black cherry indicated that radial growth did not vary among ozone sensitivity groups during any time period analyzed. Yellow-poplar radial growth varied by sensitivity group during the period 1990-1994, but not from 1997-2001. No distinct differences in growth of these trees were detected over time relative to ozone. (AL).

2. Research was conducted on a variety of projects involving the responses of native plants to ozone. This included a study of the impacts of chronic and acute ozone exposures on seedlings of tulip poplar trees (Liriodendron tulipifera) in Boone, NC, and the impacts of ozone on cutleaf coneflower (Rudbeckia laciniata), in Great Smoky Mountains National Park. Our goal is to determine how varying ozone exposures elicit foliar and biochemical responses in tulip poplar.

3. Ambient ozone induced foliar symptoms on Chambourcin grape vines that had been planted within open plots and non-filtered-air-open-top chambers while vines in filtered air chambers remained asymptomatic. Symptoms included adaxial stipple and yellowing and defoliation of the older leaves. The Vidal variety of grape, which is considered tolerant to ozone injury, exhibited no foliar injury in any of the treatments. Berry harvests were made in early October and fruit quality evaluations suggest that ambient ozone may decrease grape fruit size and juice total acidity, while increasing juice pH and Brix content. Tropospheric ozone air pollution continues to pose serious problems for the growth and productivity of agricultural crops across much of the eastern United States. The finding of ozone-injury within the open-top chambers or open plots during a summer season with the lowest ozone that has been recorded in recent years, provides further evidence that ozone is the cause of significant losses when higher during previous years. (PA)

4. Ambient concentration of ozone, the most important air pollutant, on Long Island throughout the summer growing season in 2005 was sufficiently high to cause acute injury that was followed by premature defoliation and to greatly reduce yield of sensitive snap bean plants in one of the most important agricultural counties in New York. Based on a comparison of yield from ozone-tolerant and ozone-sensitive snap bean lines, which were developed to quantify impact of ambient ozone, total weight of bean pods harvested for fresh-market consumption was 17%, 49% and 56% lower for the ozone-sensitive line in three plantings during the summer. Dry weight of mature pods was 43%, 44%, and 64% lower. Yield reduction can be expected to also occur in crops grown in this area, including some that do not develop acute injury. (NY)

Objective 2. Assess the effects of O3 on structure, function and diversity of plant communities.

1. The ozone-protectorant chemical, ethylenediurea (EDU), was effective in determining ozone sensitivity of native plant species based on dose-response experiments using open-top chambers. Cutleaf coneflower appears to be more sensitive to ozone than purple coneflower and injury was diminished by EDU applications. Results from this research suggests that chronic ozone exposures can lead to alterations in inter-species competition, species fitness or reproduction and consequently changes in species biodiversity. (AL).

2. To determine the nutritive quality of injured versus uninjured cutleaf coneflower leaves, leaves were collected at three locations in the Great Smoky Mountain National Park. Preliminary analyses indicate that injured leaves contain less nitrogen and less food value for ruminant herbivores. In addition, it appears that a strong relationship is evident between the production of total phenolics and lignin for the injured leaves, but not as strong for uninjured ones. The implication of these results on animal nutrition is currently being explored in more detail. (AL)

Objective 3. Examine the joint effects of O3 with other growth regulating factors on crop and tree growth and productivity.

1. The first year of a soybean-wheat rotation no-till experiment and the third year of a soybean-corn rotation open-air exposure experiment were completed to assess long-term effects of elevated ozone and carbon dioxide on biomass production and yield. In soybean, elevated carbon dioxide increased biomass and seed yield, elevated ozone decreased biomass and yield, and the deleterious effects of ozone were partially ameliorated by carbon dioxide when the two gas treatments were combined. (USDA, NC, IL)

2. Two winter-wheat (Triticum aestivum) cultivars, Gore and Susquehanna, were treated with elevated carbon dioxide and ozone individually and in combination. Elevated carbon dioxide resulted in stomatal closure and, under low ozone, induced antioxidant changes that could enhance defensive capacity for oxidative stress. Yield under the combination of elevated ozone and carbon dioxide tended to be greater than for elevated ozone alone. The results suggest that plant response to ozone depends upon a number of factors working together. The availability of high pools of antioxidants may further contribute to enhanced oxidative defense capabilities. (NJ)

3. During early August 2004, red and white clover foliage was collected from the elevated carbon dioxide and ozone treatment rings at the aspen FACE site in Rhinelander, WI. Foliage was analyzed for dry matter, N, soluble phenolics, in vitro digestibility and cell-wall constituents, which are utilized to predict a relative food value. Ozone appears to alter the nutritive quality of these species irrespective of carbon dioxide; i.e., the response is similar regardless of plants growing in an ambient or elevated carbon dioxide environment. Elevated carbon dioxide does not ameliorate the ozone effect on nutritive quality, and elevated carbon dioxide does not appear to affect nutritive value of these species. Ozone appears to induce an increase in lignification, which lowers its food value. (AL).

Objective 4. Examine the molecular and physiological basis of O3 toxicity and tolerance in plants.

1. Arabidopsis thaliana mutants with key deletions in the G-protein pathway were not different from wild-type controls when using peroxidase enzyme activity to assess plant response to ozone concentrations as high as 125 ppb. The implication is that the G-protein pathway may not be a good molecular target for improving crop response to ozone stress. (USDA, NC).

2. An ozone screen for activation-tagged Arabidopsis mutants identified an ozone-sensitive genotype with 40 to 50% of the total leaf ascorbate typically present in wild-type plants. Subsequent analysis showed that a putative F-Box gene, VCF1, negatively regulates gene expression in the mannose-galactose pathway of ascorbate biosynthesis and increases ozone sensitivity. These results indicate that ascorbate has a critical role in plant sensitivity to ozone and suggests a potential target for genetically engineering increased plant tolerance to ozone. (VPI, VA).

3. Thirty soybean ancestors representing a majority of genes in modern U.S. cultivars were screened for ozone sensitivity under greenhouse conditions using foliar injury as an assessment tool. Two ancestors (Fiskeby III and Fiskeby 840-7-3) exhibited minimal ozone injury following a 6-day exposure to 80 ppb ozone. If confirmed in yield tests, these ozone-tolerant ancestors represent sources of genes for development of new ozone tolerant cultivars so that productivity can be maintained under future climate scenarios where ambient ozone concentrations are expected to be much higher than today. (USDA, NC).

Objective 5. Develop numerical models to establish relationships between ambient O3 exposures and plant responses.

5. Work currently in progress begins to address the issues of increasing population, urbanization, agricultural sustainability, air quality and global change by the development of hybrid or coupled empirical and mechanistic methodologies to relate the measured (5-years of data) dynamics of the atmosphere with corresponding changes in crop growth and productivity under ambient conditions, using alfalfa (Medicago sativa) as a model species. (MN).

Ainsworth EA, SP Long. 2005. What have we learned from 15 years of free-air CO2 enrichment (FACE)? A meta-analytic review of the responses of photosynthesis, canopy properties and plant production to rising CO2. New Phytologist 165:351-372.

Bernacchi CJ, PB Morgan, DR Ort, SP Long. 2005. The growth of soybean under free air [CO2] enrichment (FACE) stimulates photosynthesis while decreasing in vivo Rubisco capacity. Planta 220:434-446.

Booker, FL, EL Fiscus. 2005. Role of ozone flux and antioxidants in the suppression of ozone injury by elevated carbon dioxide in soybean. Journal of Experimental Botany 56:2139-2151.

Booker, FL, JE Miller, EL Fiscus, WA Pursley, LA Stefanski. 2005. Comparative responses of container- versus ground-grown soybean to elevated CO2 and O3. Crop Science 45:883-895.

Booker, FL, SA Prior, HA Torbert, EL Fiscus, WA Pursley, S Hu. 2005. Decomposition of soybean grown under elevated concentrations of CO2 and O3. Global Change Biology 11:685-698.

Burkey, KO, JE Miller, EL Fiscus. 2005. Assessment of ambient ozone effects on vegetation using snap bean as a bioindicator species. Journal of Environmental Quality 34:1081-1086.

Elagoz, V. and Manning WJ. 2005. Responses of sensitive and tolerant bush beans (Phaseolus vulgaris L.) to ozone in open-top chambers are influenced by phenotypic differences, morphological characteristics, and the chamber environment. Environmental Pollution 136:371-383.

Fiscus, EL, FL Booker, KO Burkey. 2005. Crop responses to ozone: uptake, modes of action, carbon assimilation and partitioning. Plant, Cell and Environment 28:997-1011.

Gielen, B, et al. (S Long). 2005. Net carbon storage in a poplar plantation (POPFACE) after three years of free-air CO2 enrichment. Tree Physiology 25:1399-1408.

Grantz, DA. 2005. Ozone impacts on plants. In: P Dwivedi and RS Dwivedi (eds.). Physiology of Abiotic Stress in Plants. Oxford IBH Publishing Co., New Delhi. (in press).

Grantz, DA and A Shrestha. 2005. Ozone reduces crop yields and alters competition with weeds such as yellow nutsedge. California Agriculture 59:137-143.

Hu, S, J Wu, KO Burkey, MK Firestone. 2005. Plant and microbial N acquisition under elevated atmospheric CO2 in two mesocosm experiments with annual grasses. Global Change Biology 11:213-223.

Hughes, NM, HS Neufeld, KO Burkey. 2005. Functional role of anthocyanins in high-light winter leaves of the evergreen herb Galax urceolata. New Phytologist 168:575-587.

Krupa, S.V. (Ser. ed.). 2005. Cross-Border Resource Management by R. Guo. Developments in Environmental Science. Elsevier Science, Amsterdam, The Netherlands. 300 p.

Long SP, Ainsworth EA, Leakey ADB, Morgan PB. 2005. Global food insecurity. Treatment of major food crops with elevated carbon dioxide or ozone under large-scale fully open-air conditions suggests recent models may have overestimated future yields. Philosophical Transactions of the Royal Society of London B 360: 2011-2020.

Morgan, PB, GA Bollero, RL Nelson, FG Dohleman, SP Long. 2005. Smaller than predicted increase in aboveground net primary production and yield of field-grown soybean under fully open-air [CO2] elevation. Global Change Biology 11:1856-1865.

Sanz, J., R.B. Muntifering, V. Bermejo, B.S. Gimeno and S. Elvira. 2005. Ozone and increased nitrogen supply effects on the yield and nutritive quality of Trifolium subterraneum. Atmospheric Environment 39:5899-5907.

Schaub, M, JM Skelly, JW Zhang, JA Ferdinand, JE Savage, RE Stevenson, DD Davis, KC Steiner. 2005. Physiological and foliar symptom response in the crowns of Prunus serotina, Fraxinus americana and Acer rubrum canopy trees to ambient ozone under forest conditions. Environmental Pollution 133:553-567.

Shrestha, A and DA Grantz. 2005. Ozone impacts on competition between tomato and yellow nutsedge: Above- and below-ground effects. Crop Science 45:1587-1595.

Wittig, VE, CJ Bernacchi, X-G Zhu, C. Calfapietra, R Ceulemans, P Deangelis, B Gielen, F Miglietta, PB Morgan, SP Long. 2005. Gross primary production is stimulated for three Populus species grown under free-air CO2 enrichment from planting through canopy closure. Global Change Biology 11:644-656.

Zaleski, Rosemary (2005) Characterization of yield, antioxidant and stomatal response in wheat grown in open-top chambers under variations in atmospheric ozone, carbon dioxide and soil moisture. Ph.D. Thesis, Rutgers University, New Brunswick, NJ, 254 pp.