Elevated temperature and carbon dioxide affect chlorophylls and carotenoids in Douglas-fir seedlings

The objective of this study was to determine whether increased temperature and CO2concentration would decrease or increase the concentrations of foliar pigments in 5‐yr‐old seedlings of Douglas‐fir (Pseudotsuga menziesii[Mirb.] Franco var.menziesii). Seedlings were grown for 3 yr in sunlit, controlled environment chambers under ambient conditions or with a 179 μL L−1elevation of CO2and/or a 3.5°C elevation of temperature. Current‐ and previous‐year needles were extracted with methanol for determination of chlorophyllsaandb, total carotenoids, and UV‐absorbing compounds. Interactive effects of elevated temperature and CO2on the measured responses were not significant. Current‐year needles from the elevated CO2treatment had the lowest chlorophyll and carotenoid concentrations, whereas needles of both age classes in the elevated temperature treatment had the highest concentrations of chlorophylls; current‐year needles had the highest carotenoid concentration at elevated temperature. Neither temperature nor CO2affected the concentrations of UV‐absorbing compounds or needle fresh mass significantly. Chlorophyllawas correlated with carotenoids across all treatments ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $r=0.75$ \end{document} –0.89) in both needle age classes and with chlorophyllbin most treatments.