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Title: TEMPERATURE AND CARBON DIOXIDE EFFECTS ON EASTERN GAMAGRASS: GROWTH AND YIELD

Author
item Ritchie, Jerry
item Gitz, Dennis
item Krizek, Donald
item Reddy, Vangimalla

Submitted to: Eastern Native Grass Symposium
Publication Type: Proceedings
Publication Acceptance Date: 7/3/2003
Publication Date: 10/21/2004
Citation: Ritchie, J.C., Gitz III, D.C., Krizek, D.T., Reddy, V.R. 2004. Temperature and CO2 effects on eastern gamagrass growth and yield. In: Proceeding of the Third Eastern Native Grass Symposium, October 1-3, 2002, Chapel Hill, North Carolina. p. 211-217.

Interpretive Summary: This study of eastern gamagrass in SPAR sun-lit growth chambers showed that elevated temperatures significantly increased vegetative growth at ambient and elevated carbon dioxide. The optimum temperature in our study for biomass accumulation in the shoots (35/29 C) was higher than that for the crowns and roots (27.5/21.5 C) for eastern gamagrass. Plants grown at high temperature had greater biomass than those grown at low temperature. Temperature had a greater effect on growth than carbon dioxide enrichment. Under optimum soil moisture conditions of our study, high amounts of carbon were captured in the above ground biomass for later incorporation into the soil. Based on our results for a single growing season, it is clear that eastern gamagrass accumulates high levels of carbon in the above ground biomass at elevated temperatures and carbon dioxide Much of this carbon could ultimately be incorporated in the soil to increase the organic matter and contribute to soil carbon buildup. Further studies are needed to assess the effects of carbon dioxide and temperature increases on carbon accumulation in this warm season grass and its contribution to soil carbon sequestration.

Technical Abstract: Eastern gamagrass [Tripsacum dactyloides (L.) L.] was grown in six Soil Plant Atmosphere Research (SPAR) sun-lit controlled-environment chambers (2.5 x 2.0 x 0.5 m, 16 plants per chamber) at two levels of carbon dioxide (370 and 740 ppm) and three temperatures (20/14, 27.5/21.5, and 35/29 C day/night) for 21 weeks (mid-May to mid-October 2001). Shoots (> 10 cm tall) were harvested at 8 and 16 weeks and total plants (roots, crowns, and shoots) were harvested at 21 weeks. Total plant biomass and shoot biomass increased significantly with increased temperature. Crown and root biomass increased from 20/14 C to 27.5/21.5 C then decreased from 27.5/21.5 C to 35/29 C. Biomass was consistently but not significantly higher in chambers with elevated carbon dioxide at all temperatures. Shoot to root ratios increased with increasing temperature and carbon dioxide. Our results show that temperature was the major factor affecting biomass accumulation with little effect of elevated carbon dioxide on biomass production for a single growing season. However, the higher biomass accumulation in shoots at elevated carbon dioxide as well as a consistently higher biomass for all plant parts at elevated carbon dioxide for all temperature treatments suggests the potential for a cumulative effect of carbon dioxide over time.