AOBPreview originally published online on August 28, 2008
Annals of Botany 2008 102(5):835-843; doi:10.1093/aob/mcn161
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Carbon Dioxide Enrichment Does Not Reduce Leaf Longevity or Alter Accumulation of Carbon Reserves in the Woodland Spring Ephemeral Erythronium americanum
Département de biologie et Centre d'étude de la forêt, Université Laval, Québec (Québec), Canada G1V 0A6
* For correspondence. E-mail Line.Lapointe{at}bio.ulaval.ca
Received: 29 May 2008 Returned for revision: 21 July 2008 Accepted: 29 July 2008 Published electronically: 29 August 2008
Background and Aims: Woodland spring ephemerals exhibit a relatively short epigeous growth period prior to canopy closure. However, it has been suggested that leaf senescence is induced by a reduction in the carbohydrate sink demand, rather than by changes in light availability. To ascertain whether a potentially higher net carbon (C) assimilation rate could shorten leaf lifespan due to an accelerated rate of storage, Erythronium americanum plants were grown under ambient (400 ppm) and elevated (1100 ppm) CO2 concentrations.
Methods: During this growth-chamber experiment, plant biomass, bulb starch concentration and cell size, leaf phenology, gas exchange rates and nutrient concentrations were monitored.
Key Results: Plants grown at 1100 ppm CO2 had greater net C assimilation rates than those grown at 400 ppm CO2. However, plant size, final bulb mass, bulb filling rate and timing of leaf senescence did not differ.
Conclusions Erythronium americanum: fixed more C under elevated than under ambient CO2 conditions, but produced plants of similar size. The similar bulb growth rates under both CO2 concentrations suggest that the bulb filling rate is dependant on bulb cell elongation rate, rather than on C availability. Elevated CO2 stimulated leaf and bulb respiratory rates; this might reduce feed-back inhibition of photosynthesis and avoid inducing premature leaf senescence.
Key words: Source–sink relations, assimilation rates, growth rates, CO2 enrichment, respiration, spring ephemeral, leaf senescence, bulbous plant, carbohydrate storage, Erythronium americanum
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