Stomatal density and needle anatomy of Scots pine (Pinus sylvestris) are affected by elevated CO₂

Abstract

• Morphological and anatomical characteristics of needles from different whorl levels were examined on Scots pines ( Pinus sylvestris ), grown for 4 yr under either ambient or elevated (ambient + 400 µ mol mol -1 ) CO 2 concentrations in open-top chambers.• Needle characteristics were studied using light microscopy, scanning electron microscopy and laser scanning confocal microscopy.• Under the elevated CO 2 treatment stomatal density was reduced on both adaxial and abaxial needle surfaces although the number of rows of stomata did not change significantly. Needle cross-sectional area increased by 10%; this was largely the result of an increase in needle thickness and, to a lesser extent, needle width. The increase in needle thickness was due to a large increase in mesophyll tissue. The relative area (i.e. proportion of the total area) of epidermis plus hypodermis, of resin canal, of xylem and of central cylinder decreased, whereas the relative area of needle phloem significantly increased.• The results suggest that a prolonged exposure to elevated CO 2 has an effect on needle structure, anatomical and stomatal characteristics of Scots pine needles.

Variation in needle-trace diameter in respect of needle morphology in five conifer species

“…In several studies it has been shown that elevated atmospheric CO 2 affects the morphology and structure of plant leaves by decreasing stomatal density (Woodward and Bazzaz 1988;Pearson et al 1995;Lin et al 2001) and increasing needle thickness and relative area of phloem (Lin et al 2001). Our results conclude that needle traces store some information about needle structure, and that this information can be obtained by using NTM.…”

Does timing of boron application affect needle and bud structure in Scots pine and Norway spruce seedlings?

“…The same phenomenon was found in a field study comparing Norway spruce trees with deficient and adequate B levels (Sutinen et al 2006). Increased numbers of sieve cells could be an adaptive response to increased need for transport of photoassimilate, as speculated by Lin et al (2001) for needles of Scots pine exposed to elevated CO 2 for four years.…”

Assessment of the Diversity of Leaf Epidermal Traits of Dipcadi Filamentosum Medik Among Different Co-Geographical Regions in Nigeria

“…However, unlike the response to the drought and temperature, stomatal response to elevated CO 2 had contrasting results, varying from a decrease in SD (Lin et al, 2001;Woodward and Kelly, 1995) to a lack of stomatal acclimation within a single generation in wheat (Triticumaestivum L.) and sour oranges (Citrus aurantium L.) (Estiarte et al,1994). This may also be responsible for some exceptional cases observed in the northern and southern populations of the Dipcadi filamentosum studied.…”