Photosynthesis and Yield Responses of Southern U.S.
Rice Cultivars to CO2 and Temperature. (3494)
Authors:
J. Baker* - USDA-ARS
S.-.H. Kim - USDA-ARS, Beltsville, MD D.C. Gitz - USDA-ARS, Lubbock, TX D. Timlin - USDA-ARS, Beltsville, MD V.R. Reddy - USDA-ARS, Beltsville, MD
Abstract:
A two year study was conducted to determine the effects of CO2 and air temperature on four Southern USA rice cultivars. In 2000 the rice cultivars
Cocodrie, Cypress and Jefferson were grown season-long in six outdoor, naturally sunlit, controlled environment chambers in constant day/night air temperature regimes ranging from 24 to 40 C under ambient and elevated CO2. In 2002 a more detailed study examining both main crop (MC) and ratoon crop (RC) yields was conducted on the rice cultivar Lamont with day/night air ranging from 19/15 to 35/31 C. In both experiments, plants grown at or above 35-36 C failed to produce any seed yield while CO2 enrichment increased grain yield by 46 to 71 percent among the three cultivars in 2000 at moderate air temperatures. In 2002, CO2
enrichment resulted in a non-significant increase in seed yield for the MC but more than doubled RC yields. Examination of the seasonal trends in canopy
photosynthesis revealed that enhanced RC yield was likely the result of faster re-growth and greater light capture as well as higher canopy photosynthetic rates during the RC grain filling period.
Speaker Information: Jeffrey Baker, USDA-ARS, USDA - ARS 302 West I-20, Big Spring, TX 79720; Phone: (915)263-0293; E-mail: [email protected]
Session Information: Wednesday, November 3, 2004, 4:00 PM-6:00 PM Presentation Start: 4:00 PM (Poster Board Number: 0330)
Keywords: Climate Change; Carbon dioxide; Air temperature; Rice