|Vegetative Storage Proteins: Response to Atmospheric C02|
|Written by Staff|
|Thursday, 11 October 2012 08:55|
[Illustrations, footnotes and references available in PDF version]
In a paper published in Tree Physiology, Maier et al. (2008) describe how a soil nitrogen fertilizer application affected upper-canopy needle morphology and gas exchange in approximately 20-meter-tall loblolly pine (Pinus taeda L.) trees previously exposed to elevated atmospheric CO2 concentrations (200 ppm above ambient) for nine years at the Duke Forest FACE facility in Orange County, North Carolina, USA. This work revealed that during the tenth year of exposure to elevated CO2, there was a strong enhancement (greater than 50%) of light-saturated net photosynthesis across all age classes of needles, but that the stimulation was 28% greater in current-year foliage than in one-year-old foliage. In addition, they report that current-year foliage incorporated the added nitrogen into photosynthetic components that increased the photosynthetic capacity of the current-year foliage, but that the one-year-old foliage tended to simply store extra nitrogen, which subsequently served as "an important source of nitrogen for the development of current-year foliage" via "efficient retranslocation of nitrogen from senescing one-year-old foliage to developing foliage."