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Effects of Ozone on Soybean Yields
Betzelberger, A.M., Gillespie, K.M., McGrath, J.M., Koester, R.P., Nelson, R.L. and Ainsworth, E.A. 2010. Effects of chronic elevated ozone concentration on antioxidant capacity, photosynthesis and seed yield of 10 soybean cultivars. Plant, Cell and Environment 33: 1569-1581.

The authors write that "crop losses to tropospheric ozone (O3) in the United States are estimated to cost $1-3 billion annually," and they say that "this challenge is expected to increase as O3 concentrations rise over the next half century."

What was done
In light of this "growing" problem, and their desire to learn more about it, Betzelberger et al. grew ten cultivars of soybean (Glycine max (L.) Merr.) at the SoyFACE facility near Champaign, Illinois (USA) in two different years at ambient atmospheric O3 concentrations and at elevated O3 concentrations that were 78% greater than ambient in the first year and 62% greater in the second year.

What was learned
The six researchers report that their imposed increases in the background O3 concentration decreased soybean yields by 8 to 37% among the ten cultivars, with a mean reduction of 17%.

What it means
One implication of Betzelberger et al.'s findings is that the cultivars least impacted by rising O3 concentrations should be grown more widely in the future. Another implication is that breeding for greater resistance to ozone pollution could help to mitigate the damage likely to be caused by further increases in the air's O3 content. However, the researchers note that "there has not been a significant improvement in soybean tolerance to O3 in the past 30 years," which suggests that we should probably not count on significant improvements in the next 30 years either. So what can we do about the unfortunate situation?

Perhaps the best thing that could realistically be done would be to not clamp down on the usage of fossils fuels, thereby allowing the air's CO2 content to continue to rise unimpeded until other forms of energy production are developed and implemented based on their own merits and not on the ridiculous claim of the U.S. Environmental Protection Agency that CO2 is a dangerous air pollutant, for there have been a host of studies conducted over the past decade or so that clearly demonstrate the ability of atmospheric CO2 enrichment to greatly ameliorate, or even completely compensate for, the detrimental effects of elevated O3 concentrations on soybean productivity, including the work of Miller et al. (1998), Reid and Fiscus (1998), Reid et al. (1998), Morgan et al. (2003), Booker et al. (2005), Bernacchi et al. (2006), and Mishra et al. (2008). And a quick glance at Growth Response to CO2 with Other Variables (Ozone) in our Subject Index reveals the same to be true for all other plants that have been studied in this regard as well. So if people really want to "save the planet" -- and their posterity along with it -- they need to let the biosphere get more of what it really needs, which is more CO2.

Bernacchi, C.J., Leakey, A.D.B., Heady, L.E., Morgan, P.B., Dohleman, F.G., McGrath, J.M., Gillespie, K.M., Wittig, V.E., Rogers, A., Long, S.P. and Ort, D.R. 2006. Hourly and seasonal variation in photosynthesis and stomatal conductance of soybean grown at future CO2 and ozone concentrations for 3 years under fully open-air field conditions. Plant, Cell and Environment 10.1111/j.1365-3040.2006.01581.x

Booker, F.L., Miller, J.E., Fiscus, E.L., Pursley, W.A. and Stefanski, L.A. 2005. Comparative responses of container- versus ground-grown soybean to elevated carbon dioxide and ozone. Crop Science 45: 883-895.

Miller, J.E., Heagle, A.S. and Pursley, W.A. 1998. Influence of ozone stress on soybean response to carbon dioxide enrichment: II. Biomass and development. Crop Science 38: 122-128.

Mishra, S., Heckathorn, S.A., Barua, D., Wang, D., Joshi, P., Hamilton III, E.W. and Frantz, J. 2008. Interactive effects of elevated CO2 and ozone on leaf thermotolerance in field-grown Glycine max. Journal of Integrative Plant Biology 50: 1396-1405.

Morgan, P.B., Ainsworth, E.A. and Long, S.P. 2003. How does elevated ozone impact soybean? A meta-analysis of photosynthesis, growth and yield. Plant, Cell and Environment 26: 1317-1328.

Reid, C.D. and Fiscus, E.L. 1998. Effects of elevated [CO2] and/or ozone on limitations to CO2 assimilation in soybean (Glycine max). Journal of Experimental Botany 18: 885-895.

Reid, C.D., Fiscus, E.L. and Burkey, K.O. 1998. Combined effects of chronic ozone and elevated CO2 on rubisco activity and leaf components in soybean (Glycine max). Journal of Experimental Botany 49: 1999-2011.

Reviewed 15 December 2010