Effect of Co2 enrichment on leaf anatomy in marigold (Tagets spp.), floss flower (Ageratum spp.) and blanket flower (Gaillardia spp.)

To evaluate the effect of high Co2 concentration on three ornamental plants belong to Asteraceae family, all with different morphological characteristics, namely: Marigold (compound leaves), Floss flower (opposite leaves) and Blanket flower (rosette leaves), an experiment was conducted in 2007 at Ferdosi university - Iran. Four levels of Co2 (350 as control, 700, 1050 and 1400 µl/l), as well as three plant genotypes were used as factorial arrangement based on a complete randomized design with three replications. The results showed that all studied traits were affected by Co2, plant genotypes and their interactions. Increasing Co2 concentration to 700 µl/l led to higher stomata density, epidermal cell density, stomata length, and guard cell length in all three plant genotypes. The results also showed that marigold (compound leaves) had the maximum values for stomata density, epidermal cell density, as well as stomatal index. Maximum stomata length occurred in Floss flower (opposite leaves) and maximum length and width of guard cell were observed in Blanket flower (rosette leaves).