|Allen, Leon - Hartwell|
Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/6/1999
Publication Date: N/A
Citation: Interpretive Summary: Atmospheric carbon dioxide (CO2) concentrations have increased from 280 to 365 ppm since 1800, with the most rapid rise during the last 50 years. Global warming of 1.5 to 4.5 degrees Celsius (about 3 to 8 degrees Fahrenheit) is expected when and if CO2 increases to 700 ppm. Scientists at USDA, Agricultural Research Service in Gainesville, FL studied the effect of doubled CO2 and higher temperatures on photosynthesis and dry matter production of forages, perennial peanut and bahiagrass, because little work has been done on these types of plants compared to annual crops. Elevated CO2 increased photosynthesis of perennial peanut over the whole season but increased crop photosynthesis of bahiagrass only marginally. Dry weight of perennial peanut increased 52 percent in high CO2 across the season, whereas dry weight of bahiagrass increased only 9 percent. Increasing temperature caused a significant increase of dry matter of bahiagrass but not perennial peanut. Thus in a future world of higher CO2 and temperature, perennial peanut growth should increase in response to CO2, whereas bahiagrass should respond to increasing temperature.
Technical Abstract: Concerns about climatic change have stimulated interest in the response of plants to increasing CO2 concentration and temperature. This study determined the effects of CO2 and air temperature on photosynthesis and biomass production of the C3 rhizoma peanut (Arachis glabrata Benth.) and C4 bahiagrass (Paspalum notatum Flugge) during the establishment year. Forages were grown in soil in four temperature-gradient greenhouses at temperatures of 0.0, 1.5, 3.0, and 4.5 degrees Celsius above ambient, and at CO2 concentrations of 365 and 640 ppm. Elevated CO2 accelerated establishment and ground cover of both species. Leaf and canopy photosynthesis of both species increased at elevated CO2, with greater increases in rhizoma peanut than bahiagrass. Total biomass production of rhizoma peanut and bahiagrass responded to elevated CO2 with a 52 and 9 percent increase, respectively. Increasing temperature enhanced biomass production of bahiagrass but not rhizoma peanut. Overall, the response of the C3 rhizoma peanut to elevated CO2 concentration was more positive than that of the C4 bahiagrass; however, bahiagrass responded more positively to increasing temperature.