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Title: FREE AIR-CO2 ENRICHMENT (FACE)OF C4-SORGHUM: BIOCHEMICAL COMPOSITION AND DECOMPOSITION OF SORGHUM TISSUES GROWN UNDER ELEVATED CO2 1536

Author
item CHENG, L. - UNIVERSITY OF ARIZONA
item Martens, Dean
item LEAVITT, S. - UNIVERSITY OF ARIZONA
item MATTHIAS, A. - UNIVERSITY OF ARIZONA
item WILLIAMS, D. - UNIVERSITY OF ARIZONA
item OTTMAN, M. - UNIVERSITY OF ARIZONA
item Kimball, Bruce
item Wall, Gerard - Gary
item Pinter Jr, Paul

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/2004
Publication Date: 10/31/2003
Citation: Cheng, L., Martens, D.A., Leavitt, S.W., Matthias, A.D., Williams, D.G., Ottman, M.J., Kimball, B.A., Wall, G.W., Pinter Jr, P.J. 2003. Free air-co2 enrichment (face)of c4-sorghum: biochemical composition and decomposition of sorghum tissues grown under elevated co2. {abstract}. Agronomy Abstracts CD-ROM S03-cheng358353-poster.

Interpretive Summary:

Technical Abstract: Biochemical composition of sorghum tissue grown under elevated CO2 was determined in Free-Air CO2 Enrichment (FACE) experiment during the 1998-1999 growing seasons at Maricopa, Arizona, USA. Sorghum samples were collected from FACE (560 ppmv CO2 ) wet (well-watered) and dry (water-limited), and Control (360 ppmv CO2) wet and dry plots at the end of 1999 growth season. Elevated CO2 increased cellulose and lignin by 40% and 5%, respectively, while total non-structural carbohydrates and amino acids were reduced by 8% and 7%, respectively. Phenolics were significantly higher in FACE roots, but not significant different in FACE leaves and stems. Water stress modified the CO2 effects, especially for uronic acids that were increased in FACE-wet by 7% and reduced in FACE-dry sorghum tissues by 3%. The C/N ratio in sorghum tissues was not affected by CO2, but was substantially lower under water stress. Laboratory incubation of soil amended with sorghum tissues showed the decomposition rate of FACE sorghum tissues was on average 14% lower than control sorghum tissues after 30 day incubation; consequently, 23% more new organic carbon was left in the incubated soil amended with FACE sorghum tissues based on isotope mass balance. The results confirm the slower decomposition of FACE plant tissue reported in literature apparently due to biochemical changes in the plant tissue.