Effects of CO2 Enrichment on Four Poplar Clones. I. Growth and Leaf Anatomy

Abstract

The poplar clones Columbia River, Beaupre, Robusta and Raspalje have been investigated under the present (350 μmol mol−1) and double the present (700 μmol mol−1) atmospheric CO2 concentration. Cuttings were planted in pots and were grown in open-top chambers inside a glasshouse for 92 d. The number of leaves, total length of stem, total leaf area, overall growth rate, total leaf, stem and root d. wt responded positively to increased CO2 but the leaf size and biomass allocation showed no change with CO2 enrichment. Beaupre and Robusta showed a larger growth response than either Columbia River or Raspalje. The effects of CO2 enrichment were restricted to the early phase of growth at the beginning of the growth season. Leaf cell numbers in all the clones were not affected by CO2 enrichment. Leaf thickness was affected; this was mainly the result of larger mesophyll cells and more extensive intercellular spaces.