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Title: WHOLE CANOPY RESPIRATORY RESPONSES OF RICE TO DAYTIME CARBON DIOXIDE ENRICHMENT, TEMPERATURE, AND DROUGHT

Author
item Baker, Jeffrey
item Allen Jr, Leon
item BOOTE, KENNETH - UNIVERSITY OF FLORIDA
item PICKERING, NIGEL - UNIVERSITY OF FLORIDA

Submitted to: World Resources Review
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Global climate change involves rising levels of carbon dioxide in the earth's atmosphere and may also result in more drought conditions in some areas of the world. In this paper, we review the literature on carbon dioxide and temperature effects on plants and in particular those studies on rice. We also present recent data on an experiment from the University of Florida where we examined the effects of carbon dioxide, temperature, and drought stress on rice dark respiration. Rice was grown in outdoor plant growth chambers with daytime carbon dioxide treatments of 350 and 700 ppm. Drought caused leaf senescence, reduced leaf area, above-ground biomass, and subsequent apparent canopy dark respiration expressed on a ground area basis. We detected a rapid and reversible direct inhibition of respiration with rising chamber carbon dioxide at air temperatures above 21 C. Long-term growth in elevated carbon dioxide can alter respiration due to changes in growth rates, plant biomass, tissue composition, and the associated energy costs of biosynthesis and maintenance. Lack of a complete understanding of the effects and potential interactions of environmental variables on plant respiratory processes makes it difficult to make definitive predictions concerning the effects of global climate change on plant respiration.

Technical Abstract: The purpose of this paper is to present results from a recent study on the effects of carbon dioxide (CO2) enrichment, temperature, and drought stress on whole canopy respiration of rice conducted at the University of Florida in 1994. We then provide a brief review of the literature on the effects of CO2 and temperature on plant respiration and in particular, those findings that may have relevance for rice. Rice (cv. IR-72) was grown to maturity in eight naturally-sunlit, plant growth chambers in CO2 treatments of 350 and 700 umol CO2 mol-1 air. In both CO2, water management treatments included continuously flooded (CF) controls, flood water removed, and drought stress imposed at panicle intiation (PI), anthesis (ANT), and both panicle initiation and anthesis (PI and ANT). Drought accelerated leaf senescence, reduced leaf area, above-ground biomass, and subsequent apparent canopy dark respiration were expressed on a ground area abasis (Rd). We detected a rapid and reversible direct inhibition of Rd with rising chamber CO2 at air temperatures above 21 C. Long-term acclimation to elevated CO2 can alter respiration due to changes in growth rates, plant biomass, tissue composition, and the associated energy costs of biosynthesis and maintenance. Incomplete understanding concerning the effects and potential interactions of environmental variables on plant respiratory processes precludes definitive predictions regarding global climate change effects on plant respiration.