Photosynthetic acclimation to elevated atmospheric CO2 concentration in the Florida scrub-oak species Quercus geminata and Quercus myrtifolia growing in their native environment.

摘要

Long-term effects of elevated CO2 concentration (ambient plus 350μmol mol-1) on leaf photosynthetic acclimatization of two species of a scrub-oak community, Quercus myrtifolia and Q. geminata, were studied. Plants of both species were grown in open-top chambers in their natural habitat at Kennedy Space Center within Merritt Island Wildlife Refuge, central Florida. Compared with ambient CO2, elevated CO2 stimulated photosynthetic rates by 73 and 51% for Q. geminata and Q. myrtifolia, respectively.Maximum rate of carboxylation (Vcmax) was significantly reduced by elevated CO2 in Q. myrtifolia (28%) but not in Q. geminata. Maximum rate of potential electron transport (Jmax) was not significantly reduced by elevated CO2 in either species. In response to elevated CO2, specific leaf area decreased in Q. myrtifolia (22%), but not in Q. geminata. Elevated CO2 caused a significant accumulation of sugars (54%) and starch (264%) in Q. myrtifolia leaves, but not in Q. geminata leaves. Total Rubisco activity in Q. myrtifolia leaves was reduced 40% by elevated CO2, whereas no significant reduction occurred in Q. geminata leaves. Although both species share a common habitat, they exhibited marked differences in photosynthetic acclimatization to elevated CO2concentration.