The fraction of expanding to expanded leaves determines the biomass response of Populus to elevated CO 2

Autor: F. Ian Woodward, Clive G. Jones, Jules Wynn, D. Alexander Wait
Rok vydání: 1999
Předmět:
Zdroj: Oecologia. 121:193-200
ISSN: 1432-1939
0029-8549
DOI: 10.1007/s004420050921
Popis: We examined whether the eAects of elevated CO2 on growth of 1-year old Populus deltoides saplings was a function of the assimilation responses of particular leaf developmental stages. Saplings were grown for 100 days at ambient (approximately 350 ppm) and ele- vated (ambient + 200 ppm) CO2 in forced-air green- houses. Biomass, biomass distribution, growth rates, and leaf initiation and expansion rates were unaAected by elevated CO2. Leaf nitrogen (N), the leaf C:N ratio, and leaf lignin concentrations were also unaAected. Carbon gain was significantly greater in expanding leaves of saplings grown at elevated compared to ambient CO2. The Rubisco content in expandingleaves was not aAected by CO2 concentration. Carbon gain and Rubisco content were significantly lower in fully expanded leaves of sap- lings grown at elevated compared to ambient CO2, indi- cating CO2-induced down-regulation in fully expanded leaves. Elevated CO2 likely had no overall eAect on bio- mass accumulation due to the more rapid decline in car- bon gain as leaves matured in saplings grown at elevated compared to ambient CO2. This decline in carbon gain has been documented in other species and shown to be related to a balance between sink/source balance and acclimation. Our data suggest that variation in growth responses to elevated CO2 can result from diAerences in leaf assimilation responses in expanding versus expanded leaves as they develop under elevated CO2.
Databáze: OpenAIRE
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