title: Photosynthesis in willows (Salix × dasyclados) grown at different CO2concentrations and fertilization levels.
abstract: Willows (Salix x dasyclados) were grown for 4 months in growth chambers at four nutrient and CO2levels, and photosynthesis measurements were made during the latter half of this period. Photosynthesis became saturated at lower light intensities at low CO2concentrations than at higher ones. The effect of CO2concentration on photosynthesis was greater at higher temperatures. The willows grown at the highest CO2concentration (1000 ppm) had a lower photosynthetic capacity than the others when measured at various concentrations. The effect of nutrient status on photosynthesis clearly increased with rising CO2concentrations. Although photosynthetic acclimation took place to a certain extent at higher CO2concentrations, photosynthesis still remained higher the higher the growth concentration was. At each CO2level photosynthesis increased contemporaneously with leaf nitrogen content, but at each fertilization level a rise in CO2concentration slightly increased photosynthesis and reduced the nitrogen content. The relative increase in photosynthesis achieved by a rise in CO2was greater than the corresponding increase in biomass growth, whereas the effect of fertilization was greater on biomass growth than on the rate of photosynthesis in the same willows.
authors.affiliation: Department of Biology, University of Joensuu, P.O. Box 111, SF-80101, Joensuu, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Silvola
authors.affiliation: Department of Biology, University of Joensuu, P.O. Box 111, SF-80101, Joensuu, Finland.
authors.forename: U
authors.initials: U
authors.lastname: Ahlholm
keywords: CO2 concentration; Light intensity; Nutrient status; Photosynthesis; Temperature