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Title: FREE-AIR CO2 ENRICHMENT AND DROUGHT STRESS EFFECTS ON GRAIN FILLING RATE AND DURATION IN SPRING WHEAT.

Author
item LI, AI-GUO - UNIV OF IDAHO
item HOU, YUE-SHENG - WASHINGTON ST UNIV
item Wall, Gerard - Gary
item TRENT, ANTHONY - UNIV OF IDAHO
item Kimball, Bruce
item Pinter Jr, Paul

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: The carbon dioxide (CO2) concentration of the atmosphere is rising, which may affect future precipitation patterns and soil water supply. Elevated CO2 has been known to increase the production and to reduce the adverse affects of drought in wheat. A greater level of productivity will increase potential growth of organs such as kernels. Elevated CO2 increased the number and size of organs that could grow grain. Because more and bigger kernels were produced due to elevated CO2, grain production per acre is anticipated to be greater in a future higher CO2 world, assuming that CO2 does not adversely affect climate. This increase should benefit both producers and end users.

Technical Abstract: The CO2 concentration of the atmosphere is rising, which may affect potential growth of spring wheat (Triticum aestivum L). This study determined the rate of grain-filling over the main stem and tillers in cv. Yecora Rojo grown under two levels of atmospheric CO2 concentration, 550 (elevated; FACE) or 370 (ambient; Control) umol mol-1, and two soil moisture regimes [100% (Wet) and 50% (Dry) replacement of evapotranspiration], in a free-air-CO2 enrichment (FACE) experiment conducted at the University of Arizona Maricopa Agricultural Center. Plant samples were collected every 3 to 5 d from 6 d after anthesis until plant maturity. Main stem and tiller spikes were separated into upper, middle, and lower sections. Both elevated CO2 and water treatments significantly influenced the grain-filling process. Under drought stress, elevated CO2 increased grain weight in the upper and lower sections of the main stem spike by 10 and 24%, respectively. In well- watered plants, final grain weight in the mid-section of the main stem spike was 8% higher than that measured under drought stress. Grain weight increased under elevated CO2 due mostly to an enhanced rate of grain filling, presumably because of an increase in the supply of assimilates from the leaves to the developing kernels. Increases in grain weight for well-watered plants was due to a longer grain-filling period. Later formed tiller spikes were more responsive to elevated CO2 and drought stress than main stem spikes. This study has provided us with information to understand grain growth mechanisms under a CO2-enriched world.