Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 30, 2003
Publication Date: July 30, 2003
Citation: JOHNSON, J.M., GESCH, R.W., BARBOUR, N.W. PHENOLOGY AND BIOCHEMICAL COMPOSITION OF SWITCHGRASS (C4) AND WHEAT (C3)GROWN AT CONTRASTING TEMPERATURES. AMERICAN SOCIETY OF PLANT BIOLOGISTS. 2003. ABSTRACT P. 45. Technical Abstract: Global temperatures are increasing and are expected to rise 2-6 deg C within this century. Temperatures greatly affect how plants partition photosynthates among shoots, roots and reproductive parts, which can influence decomposition rate. The objective of the following study was to compare structural and nonstructural carbohydrate partitioning between a C3 and C4 grass with increasing temperature. Switchgrass (C4; Panicum virgatum L.) and wheat (C3; Triticum aestivum L.) were grown under 18-24 and 27-33 deg C night/day temperature regimes. Phenological data was collected (plant height, leaf area, tiller number, biomass) and plant material sampled at two developmental stages (four leaf and heading). Concentrations of nonstructural and structural carbohydrates, and lignin were determined for above and below ground organs. For switchgrass, above and below ground biomass, tillering, and leaf area increased with growth temperature while wheat growth declined dramatically. Starch concentration was about three times lower in leaves, stems and roots of switchgrass and 2 to 8-times lower in leaves and stem of wheat grown at 27-33 deg C n/d compared to plants grown at 18-24 deg C n/d. High growth temperatures reduced hexose concentrations in leaves and roots of switchgrass, but sucrose was only reduced in roots. Lignin and cellulose concentrations increased in switchgrass roots and stems, and wheat stems grown at 27-33 deg C n/d compared to 18-24 deg C n/d. Results indicate that although non-structural carbohydrates may decrease with increasing temperature, structural components increase. This likely will vary between C3 and C4 species.