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Title: Direct and Acclimatory Responses of Dark Respiration and Translocation to Temperature

item Bunce, James

Submitted to: Annals of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2007
Publication Date: 5/4/2007
Citation: Bunce, J.A. 2007. Direct and Acclimatory Responses of Dark Respiration and Translocation to Temperature. Annals Of Botany. 100:67-73.

Interpretive Summary: The carbon dioxide concentration in the atmosphere is rising, and this may be causing global warming, which has many negative consequences for agriculture. Global warming might cause plants to release more carbon dioxide, making global warming more severe. To improve predictions of whether global warming will increase carbon dioxide release from plants, we studied how carbon dioxide release from plants responds to short term and long term warming. We found that long term warming increased carbon dioxide release either not at all or even more than the large increase caused by short term warming, depending on how the movement of food within the plant was controlled, making generalizations difficult. This information will be of use to scientists studying how the global carbon budget may respond to global warming, which will affect the degree of global warming.

Technical Abstract: Accounting for the acclimation of respiration of plants to temperature remains a major problem in analysis of carbon balances of ecosystems. It is possible that the thermal acclimation of leaf respiration simply reflects changes in substrate supply caused by temperature effects on translocation. To test this hypothesis, direct and acclimatory responses to temperature of respiration and translocation in the dark were investigated in mature leaves of soybean and amaranth. In both species increases in temperature during the dark led to exponential increases in initial rates of respiration. However, respiration averaged over the whole dark period increased much less with temperature, because of depletion of substrates at the end of the dark period at warmer temperatures. In soybean, translocation also increased with temperature, and there was a linear relationship between respiration and translocation. In soybean, both respiration and translocation fully acclimated to temperature, while in amaranth, translocation in the dark was independent of temperature, and respiration did not acclimate to temperature. Respiration and translocation rates both decreased with decreased photosynthesis during the prior day in both species. It was concluded that substrate supply limited total night time respiration in both species at warm temperatures and following days with low photosynthesis. The depletion of respiratory substrates resulted in apparent acclimation of respiration to warm temperatures within one night in both species. However, changes in substrate supply with long-term growth temperature did not directly cause acclimation of respiration to temperature in either species.