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Submitted to: Annals of Botany
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/10/2004 Publication Date: 3/29/2004 Citation: Bunce, J.A. 2004. A comparison of the effects of carbon dioxide concentration and temperature on respiration, translocation, and nitrate reduction in darkened soybean leaves. Annals Of Botany. 93:665-669. Interpretive Summary: How plant respiration may respond to the increasing concentration of carbon dioxide in the atmosphere is uncertain, partly because the existence of short-term responses of respiration to carbon dioxide concentration remains controversial. Any changes in respiration caused by increasing atmospheric carbon dioxide could have important effects on crop growth. This work compared responses of respiration of soybean leaves and two processes dependent on the energy supplied by respiration, translocation and nitrate reduction, to changes in carbon dioxide concentration and temperature. Low temperature and elevated concentrations of carbon dioxide reduced rates of respiration, translocation and nitrate reduction, while increased temperature and low concentrations of carbon dioxide increased rates of all three processes. A given change in the rate of respiration was accompanied by the same change in the rate of translocation or nitrate reduction, regardless of whether the altered respiration was caused by a change in temperature or by a change in carbon dioxide concentration. Because there is no dispute about responses of respiration to temperature, these results make it highly unlikely that the observed responses of respiration rate to carbon dioxide concentration were artifacts due to errors in the measurement of respiration in this case. This work will be of interest to scientists predicting responses of plants to rising atmospheric carbon dioxide. Technical Abstract: Respiration of autotrophs is an important component of their carbon balance as well as the global carbon dioxide budget. How autotrophic respiration may respond to increasing carbon dioxide in the atmosphere remains uncertain. The existence of short-term responses of respiration rates of plant leaves to carbon dioxide concentration is controversial. Short-term responses of respiration to temperature are not disputed. This work compared responses of leaf dark respiration and two processes dependent on the energy supplied by dark respiration, translocation and nitrate reduction, to changes in carbon dioxide concentration and temperature imposed on mature soybean leaves for a single 8 h dark period. Low temperature and elevated concentrations of carbon dioxide reduced rates of respiration, translocation and nitrate reduction, while increased temperature and low concentrations of carbon dioxide increased rates of all three processes. A given change in the rate of respiration was accompanied by the same change in the rate of translocation or nitrate reduction, regardless of whether the altered respiration was caused by a change in temperature or by a change in carbon dioxide concentration. These results make it highly unlikely that the observed responses of respiration rate to carbon dioxide concentration were artifacts due to errors in the measurement of carbon dioxide exchange rates in this case. |
