Project No. and Title: / NE1030 Characterization and Mechanisms of Plant Responses to Ozone in the U.S.
Period Covered: / 10-2009 to 09-2010
Date of Report: / 23-Sep-2010
Annual Meeting Dates: / 15-Jul-2010 to 17-Jul-2010
Participants
§ Best, Teodora () Penn State University, State College, PA
§ Booker, Fitzgerald () USDA-ARS Plant Sciences, Raleigh, NC
§ Vince Brisini, RRI Energy Corporation
§ Burkey, Kent () - USDA-ARS Plant Science Unit, Raleigh, NC
§ Carlson, John () Penn State University, State College, PA
§ Maria Cazorla, Ph.D. student, The Penn State University
§ Chappelka, Art () - Auburn University, Auburn, Al
§ Decoteau, Dennis () Penn State University, State College, PA
§ Fiscus, Edwin () USDA-ARS Plant Science Unit, Raleigh, NC
§ Nicholas Gilliland () Auburn University, Auburn, AL
§ Grantz, David () - University of California - Riverside, Riverside, CA
§ Herr, Josh () Penn State University, State College, PA
§ Knighton, Raymond () USDA-NIFA, Washington, DC
§ Neufeld, Howard () Appalachian State University, Boone, NC
§ Holly Salazer, Air Resource Manager, National Park Service, The Penn State University
§ Savage, Jim () - Penn State University, State College, PA
§ Skelly, John () Penn State University, State College, PA (retired)
§ Smith, Margaret () - Cornell University, Ithaca, NY
§ Wiese, Cosima () Misericordia University, Dallas, PA
§ Zilinskas, Barbara () Rutgers Univ., New Brunswick, NJ
Brief Summary of Minutes of Annual Meeting
Chair David Grantz welcomed everyone to the meeting and thanked host, Dennis Decoteau, for organizing the meeting this year. We were reminded that the current project expires in 2012 and that we should be thinking about approaches for the new proposal. Grantz encouraged the group to think about possible collaboration activities, funding opportunities and the need to increase student participation. Dennis Decoteau welcomed the group and thanked Jim Savage for his help setting up for the meeting. Jim is the primary caretaker of the Demonstration Center and has done a great job maintaining and improving the facility. Margaret Smith, Project Administrator, encouraged the group to continue meeting its multi-state project objectives. Collaborative research is a component of Hatch Fund projects, and 25% of each projects fund must be spent on it. Our annual report should highlight multi-state research activities. She went on to say that our project renewal process should begin now. The current project terminates on September 30, 2012. A request to write a proposal renewal is due to NIMSS by March 2011. The request should emphasize what’s next in the projects objectives and how it will take advantage of the multi-state approach. Ray Knighton, our USDA representative, described the four institutes in the newly formed NIFA office, formerly known as CSREES. The institute of Energy, Environment and Climate Change is where he is now assigned. The focus of the funding program has been narrowed compared to previous years but the scale of the projects is much larger. Resources allocated to each project were increased to promote multidisciplinary teams whose research will have impact, in this case, on climate change mitigation and agricultural production problems associated with climate change. Emphasis will be on projects that can develop approaches that will be viable for use in the field in short order. David Grantz conducted the business meeting. A committee was formed, consisting of Art Chappelka, Fitz Booker and Dave Grantz to write the request to renew the project proposal, due for submission by March 2012. Location of the next meeting will either be on Long Island, hosted by Meg McGrath, or at Rutgers University, hosted by Barbara Zilinskas. Art Chappelka succeeded Dave as Chair of the project. The meeting was adjourned at 3:00 pm, July 16, 2010.
Accomplishments
Activities of the participating experiments are guided by the Objectives of the Current approved Project Proposal. These activities and achievements follow, organized by NE-1030 Project Objectives, and by approaches.
OBJECTIVE 1. Describe the spatial - temporal characteristics of the adverse effects of current ambient O3 levels on crop productivity, including the development of numerical models to establish cause effect relationships that apportion the ozone contribution.
1a. spatial analysis of ozone impacts on crops. A collaboration between Booker, Burkey, Fiscus and Ainsworth of USDA/ARS, NC State University and the University of Illinois, considered the elevated concentrations of ground-level O3 that are frequently measured over farmland regions in many parts of the world. While numerous experimental studies show that O3 can significantly decrease crop productivity, independent verifications of yield losses at current ambient O3 concentrations in rural locations are sparse. In this study, soybean crop yield data during a 5-year period over the Midwest of the United States were combined with ground and satellite O3 measurements to provide evidence that yield losses on the order of 10% could be estimated through the use of a multiple linear regression model. Yield loss trends based on both conventional ground-based instrumentation and satellite-derived tropospheric O3 measurements were statistically significant and were consistent with results obtained from open-top chamber experiments conducted by ARS researchers in Raleigh, NC and an open-air experimental facility (SoyFACE) in central Illinois, conducted by ARS researchers there. Extrapolation of these findings supports previous studies that estimate the global economic loss to the farming community of more than $10 billion annually. (NC, IL,).
1b. diurnal trends in ozone sensitivity of vegetation. A collaboration of the University of California at Riverside (R. Heath) University of California Kearney Agricultural Center (D. Grantz), and USDA/ARS (K. Burkey) has addressed the factors that determine the sensitivity of extensive vegetation to ozone. In general these are only crudely characterized. In order to support efforts to model extensive regional impacts, it is necessary to parameterize the steps of ozone injury, and to characterize the variability among populations. There are three major steps for plant injury by ozone (O3). These are entrance of O3into the leaf (Flux, F), overcoming by O3 metabolic defenses (antioxidant capacity, A), and the actual attack of the effective dose of O3 (Deffective) on bioreceptors (Injury, I).This can be expressed mathematically. Current approaches model gs (stomatal conductance) and [O3] from meteorological data, the species composition of the ground cover, and air quality monitoring data. However, A is assumed to be constant. Recent use of flux (F) is an improvement over previous use of exposure ([O3]) to estimate injury. We have tested the hypothesis that defense capacity (A) may vary diurnally, and may therefore control the amount of injury caused by a given atmospheric ozone concentration. If so a specific O3 flux (F) will yield a different Deffective and thus a different I, at different times of the day, so that this will need to be considered in modeling of regional O3 impacts. From knowledge of how much O3 enters the leaf (F) and how much injury occurs (I), we can calculate the initial defense capacity of the leaf (A). Exposure must be rapid enough that tissues have insufficient time for induction of additional defense capacity. We have developed the first demonstration that defense capacity varies diurnally, and have explored the mechanism, using Pima cotton, cv. S-6, grown in a greenhouse. Injury was determined from digital photo analysis of necrosis, chlorophyll content (SPAD, Minolta) and summed abaxial and adaxial stomatal conductance (LiCor 1600) 6-7 days after exposure. Total antioxidant capacity, ascorbic acid and dehydroascorbic acid content were determined on non-exposed leaves at different times of day. Injury induced by an (interpolated) O3 dose of 19.8 mol m-2, exhibited a clear diurnal trend, shown by foliar necrosis, chlorophyll content (SPAD) and stomatal conductance, all obtained at 6 days after exposure for a 15 minute pulse. Leaves were most sensitive near 3:00 p.m. in repeated experiments. Antioxidant levels of foliar ascorbic acid and of total foliar antioxidant capacity exhibited a moderate peak near midday, but leaf injury was also greatest at this time. Regression relationships between sensitivity to O3 injury and various measures of antioxidant status were not significant. While the diurnal nature of ozone sensitivity is confirmed, the mechanism remains to be elucidated. These data indicate that parameterization of models of O3 injury to vegetation will require measures of inherent defense capability, for which time of day may be a key determinant. (CA, NC)
1c. Snapbean model system demonstrates ozone impacts on crops. The continuation of this study will strengthen our understanding of the impact of ambient ozone on plants and crop productivity. In NY, McGrath has been assessing impact on plant productivity of ambient ozone occurring on Long Island, where she is stationed, by growing the ozone-sensitive and ozone-tolerant snap bean lines that were developed for use in quantifying ozone impact. Each year there have been three successive field plantings to cover the entire growing period for beans in the area. As they developed, bean pods were harvested repeatedly from some plants when immature and at a size typical for fresh-market consumption. Pods were harvested from the other plants when mature and dry. Plants were examined routinely for ozone injury. Injury and defoliation due mainly to ozone injury were rated. Ozone concentration data were obtained from a monitor maintained at the research site (LIHREC) by the NYC DEC Air Quality Division. Results from 2009 research were analyzed and another experiment was conducted over the past year for this reporting period. In 2009, the ozone-sensitive snap bean line S156 yielded less than the tolerant line R331 when grown under ambient ozone conditions. Total weight and number of bean pods harvested for fresh-market consumption from planting 1 (22 May) plants was 28% and 19% lower, respectively, for S156 compared to R331 (pods were harvested from 17 July through 21 Aug). There was a 55% and 46% reduction in these yield variables, respectively, for planting 2 (22 June) plants (harvested 10 Aug through 9 Sept). Reduction was 33% and 16%, respectively, for planting 3 (16 July) plants (harvested 4 Sept through 6 Oct). These differences were similar to greater than in previous years. Mature yield data has not yet been collected. Exposure to ozone caused acute foliar injury in all three plantings. The visible symptom was bronzing. The sensitive line became more severely affected than the tolerant one. Severely affected leaves eventually died and dropped. For example, injury was first observed on Planting 1 plants on 19 June. Average percentage of leaf tissue with bronzing (determined by estimating the incidence or proportion of leaflets with symptoms and the average severity on affected leaves) was 0.04% and 5.6% for R331 and S156, respectively, on 11 July, which was 6 days before the first pods were ready for harvest. Average percentage of leaf tissue with bronzing had increased to 0.5% and 64% by 27 July and 2.4% and 70% by 1 Aug. (NY) In New Jersey, Zilinskas monitored the effects of ambient ozone on the productivity of two snapbean cultivars R331 (ozone-tolerant) and S156 (ozone-sensitive) over the 2009 growing season. Following a very wet month of June, we planted the two snapbean cultivars in East Brunswick, NJ, on July 1, 2009, two weeks after our usual planting date. We closely adhered to the field design and conditions agreed upon by the four field stations in the US that are collaborating on this project. Throughout the growing season, ambient ozone levels and meteorological data were recorded at each site. At each field station, we made multiple harvests of marketable pods at 49, 56, 63, 69 and 76 days after planting. In the 2009 season, peak pod number and fresh weight (of both cultivars) occurred at the second harvesting date. A statistically significant decrease in total pod fresh weight of marketable snapbeans was observed in S156 relative to R331 in three of the five harvest dates, where the fresh weight of marketable pods of the ozone-sensitive cultivar was between 37% and 73% less than that of the ozone-tolerant cultivar. A final harvest of snapbeans was conducted at a uniform 84 days after planting. At this harvest date in the 2009 growing season, a significant proportion of the pods were immature (without seeds) or green. The number of seeds and the dry weight of seeds and pods from the two cultivars were significantly different, with yield reductions in the sensitive relative to the tolerant cultivar of 26%, 47% and 50%, respectively. There was no significant difference in the pod number of the sensitive cultivar relative to the tolerant cultivar. (NJ) The meteorological and ozone data, coupled with the crop yield data, will be analyzed for the several states where this field experiment has been conducted and incorporated into a numerical model by Dr. S. Krupa (MN) to establish a relationship between ambient ozone exposures and crop responses. (MN)
1d. ozone impacts on plants with C4 photosynthetic systems. A number of food and potential biofuel crops in California utilize the C4 photosynthetic pathway. This is considerable desirable due to the inherent water use efficiency of this mode of carbon acquisition. In the studies of the National Crop Loss Assessment and more recently (maize reduced by 4-8%, relative to soybean of 22%, for example), these types of plants have been considered to be tolerant of ozone. We decided to investigate genotypes of the Saccharum complex which are being considered as sources of biofuel, both through easily fermented sugars from commercial sugarcane clones, but also for lingo-cellulosic feedstocks from high fiber energy canes, which are relatively low in sugar. Existing genotypes were not developed in areas subject to high ozone. A locally grown clone of sugarcane, favored by farmers of southeast asian descent, was the most sensitive. A commercial sugarcane clone from Texas was reduced in biomass production by 30%, the southeast asian clone was reduced by about 55%, while two clones with high percentage of the wild relative, Saccharum spontaneum, were not significantly affected. The most sensitive clone was inhibited in dry matter production by 38% at 12 hour mean ozone of 59 ppm, and by 75% at 117 ppm. This is substantial sensitivity to ozone, relative even to sensitive crops such as Pima cotton. C4 crops are similar to C3 crops in exhibiting a range of ozone sensitivity. It is not warranted to assume that C4 crops will exhibit the high levels of ozone tolerance observed in early studies. (CA)