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Submitted to: International Journal of Plant Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 1/1/2003 Publication Date: 3/1/2003 Citation: Bunce, J.A. 2003. Responses of seedling growth to daytime or continuous elevation of carbon dioxide. International Journal of Plant Science. 164:377-382. Interpretive Summary: The concentration of carbon dioxide in the atmosphere is rising rapidly. With new technology, it has recently become possible to study the responses of plants to higher concentrations of carbon dioxide under natural conditions. In some such studies elevated concentrations of carbon dioxide are supplied continuously, while in other studies supplemental carbon dioxide is given only during the daytime. The purpose of this work was to determine, for a range of plants species, whether plant growth rates differed depending on whether elevated carbon dioxide was provided continuously or only during the daytime. For all five of the species examined, it was found that growth rates differed between these carbon dioxide treatments. Some species grew faster when elevated carbon dioxide was given continuously, while others grew faster when it was supplied only in the daytime. The results suggest that the growth of plants may be affected by how supplemental carbon dioxide is given. This information will be of use to scientists designing experiments to determine how the rising concentration of carbon dioxide in the atmosphere may affect plant growth. Technical Abstract: In some studies of ecosystem responses to elevated carbon dioxide, supplemental carbon dioxide is supplied only during the daytime, while in others it is supplied continuously. The purpose of the work presented here was to determine for several species whether seedling growth differed depending on whether carbon dioxide was elevated only during the daytime or continuously. Redroot pigweed, alfalfa, soybean, red maple and chestnut oak were grown in controlled environment chambers using 350 and 700 ppm carbon dioxide as the test concentrations. For the herbaceous species a comparison was made between responses to the carbon dioxide treatments under constant temperatures and responses with a day/night temperature difference. In all of these species and for all temperature regimes, plant growth differed significantly depending on whether carbon dioxide was elevated continuously or only in the daytime. Biomass at the final harvest differed by as much as 50% between these treatments. Species differed in whether growth was faster or slower with continuous carbon dioxide elevation, and in the three species examined it was found that the response to these treatments differed for regimes with constant compared with diurnally varying temperatures. The results indicate that seedling growth often responds to the carbon dioxide concentration at night when daytime concentration is elevated. |
