Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 20, 2007
Publication Date: July 1, 2008
Citation: Ainsworth, E.A. 2008. Rice Production in a Changing Climate: A Meta-analysis of Responses to Elevated Carbon Dioxide and Elevated Ozone Concentration. Global Change Biology. 14:1642-1650. Interpretive Summary: Rice is one of the most important food sources on the planet and is consumed by over half of the world’s population. Considerable increases in yield are required over this century to continue feeding the world's growing population. This work synthesized all of the published studies to date on rice responses to two elements of global change, rising atmospheric carbon dioxide concentration and rising ground-level ozone concentration. Elevated carbon dioxide concentrations improved rice yields, while elevated ozone concentrations reduced rice yields. This work also investigated which yield components were affected by elevated carbon dioxide and elevated ozone concentrations. Grain mass, panicle number and grain number were all increased by elevated carbon dioxide concentration, while grain number and grain mass were reduced by elevated ozone. This information provides the best estimates of rice responses to climate change, and synthesizes all of the literature to date, which is useful for breeders who are trying to maximize rice production in the future and modelers who are trying to simulate future food supply.
Technical Abstract: Rice is arguably the most important food source on the planet and is consumed by over half of the world’s population. Considerable increases in yield are required over this century to continue feeding the worlds growing population. This meta-analysis synthesizes the research to date on rice responses to two elements of global change, rising atmospheric carbon dioxide concentration and rising tropospheric ozone concentration. On average, elevated carbon dioxide (627 ppm) increased rice yields by 23%. Modest increases in grain mass and larger increases in panicle and grain number contributed to this response. The response of rice to elevated carbon dioxide varied with fumigation technique. The more closely the fumigation conditions mimicked actual field conditions, the smaller the stimulation of yield by elevated carbon dioxide. Free air concentration enrichment (FACE) experiments showed only a 12% increase in rice yield. The rise in atmospheric carbon dioxide will be accompanied by increases in tropospheric ozone and temperature. When compared to rice grown in charcoal filtered air, rice exposed to 62 ppb ozone showed a 14% decrease in yield. Many determinants of yield, including photosynthesis, biomass, leaf area index, grain number and grain mass were reduced by elevated ozone. While there have been too few studies of the interaction of carbon dioxide and ozone for meta-analysis, the interaction of temperature and carbon dioxide has been studied more widely. Elevated temperature treatments negated any enhancement in rice yield at elevated carbon dioxide, which suggests that identifying high temperature tolerant germplasm will be key to realizing yield benefits in the future.