Submitted to: Environmental and Experimental Botany
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/8/2007
Publication Date: 12/1/2007
Citation: Kim, S., Gitz, D.C., Sicher Jr, R.C., Baker, J.T., Timlin, D.J., Reddy, V. 2007. Temperature dependence of growth, development, and photosynthesis in maize under elevated CO2. Environmental and Experimental Botany. 61:224-236. Interpretive Summary: Global atmospheric carbon dioxide concentrations are rising. As a consequence, global surface air temperature is also expected to increase. Because changes in carbon dioxide concentration and temperature are likely to occur concurrently, it is critical to evaluate their interactive effects on physiological processes in crop plants such as corn which is a globally important grain crop. We investigated the temperature responses of photosynthesis, growth, and development of corn plants grown in a wide range of temperatures under current and doubled carbon dioxide concentrations. The objective was to test if the temperature dependence of these processes was altered by carbon dioxide enrichment. We then applied temperature response functions for modeling photosynthesis and development of corn plants at current and elevated carbon dioxide concentrations. Growth and development of corn plants responded to growth temperatures but not to carbon dioxide enrichment. Temperature dependence of growth, photosynthesis, and development were comparable between current and enhanced carbon dioxide treatments. We conclude that the temperature dependence of growth, development, and photosynthesis is conserved under elevated carbon dioxide concentration in corn. The findings of this research has a significant implication for predicting the responses of corn to different global change scenarios and will be useful for other scientists, modelers, and policymakers in assessing the impacts of climate change on crop production.
Technical Abstract: Global atmospheric carbon dioxide concentrations (Ca) are rising. As a consequence, recent climate models have projected that global surface air temperature may increase 1.4 to 5.8 degrees C with the doubling of Ca by the end of the century. Because changes in Ca and temperature are likely to occur concomitantly, it is important to evaluate how temperature dependence of key physiological processes are affected by rising Ca in major crop plants including maize (Zea mays L.), a globally important grain crop with C4 photosynthetic pathway. We investigated the temperature responses of photosynthesis, growth, and development of maize plants grown at five temperature regimes ranging from 19/13 to 38.5/32.5 degrees C under current and doubled Ca using sunlit controlled environmental chambers in order to test if the temperature dependence of these processes was altered by elevated Ca. Leaf and canopy photosynthetic rates, C4 enzyme activities, leaf appearance rates, above ground biomass accumulation and leaf area were measured. We then applied temperature response functions (e.g., Arrhenius and Beta distribution models) to fit the measured data in order to provide parameter estimates of temperature dependence for modeling photosynthesis and development at current and elevated Ca in maize. Biomass, leaf area, leaf appearance rate, and photosynthesis measured at growth Ca were not changed in response to CO2 enrichment. Carboxylation efficiency and the activities of C4 enzymes were reduced with CO2 enrichment indicating possible photosynthetic acclimation of the C4 cycle. All measured parameters responded to growth temperatures. Leaf appearance rate and leaf photosynthesis showed curvilinear response with optimal temperatures near 31 and 33 degrees C respectively. Total above ground biomass and leaf area were negatively correlated with growth temperature. Temperature dependence of leaf appearance rate, biomass, leaf area, leaf and canopy photosynthesis, and C4 enzyme activities were comparable between current and enhanced Ca as the interactive effects between CO2 and temperature treatments were not significant. We conclude that the temperature dependence of growth, development, and photosynthesis is conserved under elevated Ca in maize and that the corresponding parameter values in maize models can be used to predict the effects of elevated Ca without re-parameterization.