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Research Project: Enabling Management Response of Southeastern Agricultural Crop and Pasture Systems to Climate Change

Location: Soil Dynamics Research

Title: Varied growth response of cogongrass ecotypes to elevated CO2

Author
item Runion, George
item Prior, Stephen - Steve
item CAPO-CHICHI, L - Alberta Research Council
item Torbert, Henry - Allen
item VAN SANTEN, EDZARD - Auburn University

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2015
Publication Date: 1/5/2016
Publication URL: https://handle.nal.usda.gov/10113/62453
Citation: Runion, G.B., Prior, S.A., Capo-Chichi, L.J., Torbert III, H.A., Van Santen, E. 2016. Varied growth response of cogongrass ecotypes to elevated CO2. Frontiers in Plant Science. 6:1182. doi:10.3389/fpls.2015.01182.

Interpretive Summary: Cogongrass is an invasive, long-lived grass introduced to the U.S. from Asia. It is one of the top ten worst weeds in the world and a major problem in the Southeast US. Cogongrass plants from differing populations were collected across the Southeast from Florida, Louisiana, Mobile, and North Alabama along with a Hybrid (cross of Louisiana and Mobile) and a Red-tip commercially available ornamental variety. All plants were grown under ambient and elevated (ambient plus 200 ppm) atmospheric CO2 for 6 months. Elevated CO2 increased average dry weight (13%), height growth and both nitrogen and water use efficiencies, but lowered tissue nitrogen concentration; these are typical grass responses to elevated CO2. The Hybrid tended to exhibit the greatest growth (followed by Louisiana, North Alabama, and Florida) while the Red-tip and Mobile plants were smallest. Also, the Hybrid, Louisiana, Florida, and/or North Alabama plants generally showed a positive response to CO2 while the Mobile and Red-tip did not. Cogongrass is a problematic invasive weed in the southeastern U.S. and some populations may become more so as atmospheric CO2 continues to rise. This could have serious implications for future weed control strategies.

Technical Abstract: Cogongrass [Imperata cylindrica (L.) P. Beauv] is an invasive C4 perennial grass which is listed as one of the top ten worst weeds in the world and is a major problem in the Southeast US. Five cogongrass ecotypes (Florida, Hybrid, Louisiana, Mobile, and North Alabama) collected across the Southeast and a red-tip ornamental variety were container grown for six months in open top chambers under ambient and elevated (ambient plus 200 ppm) atmospheric CO2. Elevated CO2 increased average dry weight (13%) which is typical for grasses. Elevated CO2 increased height growth and both nitrogen and water use efficiencies, but lowered tissue nitrogen concentration; again, these are typical plant responses to elevated CO2. The hybrid ecotype tended to exhibit the greatest growth (followed by Louisiana, North Alabama, and Florida ecotypes) while the red-tip and Mobile ecotypes were smallest. There were some interactions of CO2 with ecotype; when these were significant, the hybrid, Louisiana, Florida, and/or North Alabama ecotypes generally showed a positive response to CO2 while the Mobile and red-tip ecotypes did not. Cogongrass is a problematic invasive weed in the southeastern U.S. and some ecotypes may become more so as atmospheric CO2 continues to rise.