|Feng, Zhaozong - UNIVERSITY OF TOKYO|
|Kobayashi, Kazuhiko - UNIVERSITY OF TOKYO|
Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2008
Publication Date: November 1, 2008
Citation: Feng, Z., Kobayashi, K., Ainsworth, E.A. 2008. Impact of elevated ozone on growth, physiology and yield of wheat (Triticum aestivum L.): A meta-analysis. Global Change Biology. 14(11)2696-2708. Interpretive Summary: This quantitative analysis summarized all of the studies of wheat responses to elevated tropospheric ozone concentration published between 1980 and 2007. The objective was to summarize the mean response of wheat to elevated tropospheric ozone and to investigate how method of fumigation, different ozone concentrations, plant developmental stage and additional environmental factors like drought altered the response. The results suggest that elevated ozone depresses wheat yields by 29%. Even in studies where the ozone level was low (between 31 and 50 parts per billion), there was an 18% decrease in wheat yield compared to wheat grown in ozone-free air. The response of spring wheat to elevated ozone did not differ from that of winter wheat. These results provide a baseline for determining how current and future levels of ozone are affecting yields of one of the world's major cereals. Further, this study provides critical information for new field experiments in China.
Technical Abstract: We quantitatively evaluated the effects of elevated ozone (O3) on growth, leaf chemistry, gas exchange, grain yield and grain quality by means of meta-analysis of published data. Our database consisted of 53 peer-reviewed studies published between 1980 and 2007, taking into account wheat type, ozone fumigation method, rooting environment, ozone concentration, developmental stage, and additional treatments such as drought and elevated [CO2]. The results suggested that elevated [O3] is depressing wheat yield by 29% (CI 24-34%) and above-ground biomass by 18% (CI 13-24%), where CI is the 95% confidence interval. Even in studies where the [O3] range was between 31- 50 ppb (average 43 ppb), there was a significant decrease in yield (18%) and biomass (16%) relative to carbon-filtered air (CF). Elevated [O3] significantly increased grain protein content and thereby improved grain quality. There was no significant response difference between spring wheat and winter wheat. Wheat grown in field showed larger decreases in leaf photosynthesis parameters than wheat grown in <5 L pots. Open-top chamber fumigation system induced a larger reduction than indoor growth chambers, when plants were exposed to elevated [O3]. The detrimental effect was progressively greater as the average daily [O3] increased, with very few exceptions. The impact of O3 increased with developmental stages, with the largest detrimental impact during grain filling. Both drought and elevated [CO2] significantly ameliorated the detrimental effects of elevated [O3], which could be explained by a significant decrease in O3 uptake resulting from decreased stomatal conductance.