When take up water, guard cells expand and close the stomatal aperture.

We were unable to detect a correlation between guard cell potassium content and stomatal aperture size.

Plants regulate the rate of transpiration by controlling the size of the stomatal apertures.

Stomatal density and stomatal aperture lengths were also determined.

Size of stomatal aperture.

Potassium is also responsible for the control of ion movement through membranes and water status of stomatal apertures.

Key words: stomatal aperture, potassium, calcium, X-ray microanalysis.

The paramount importance of control of stomatal aperture in influencing internal water balance of plants is emphasized.

In green plants, after a decrease in light intensity, species time to equilibrium of stomatal aperture was related as follows:

A small proportion of these stomata also contain high levels of silicon and are characterized by a constricted stomatal aperture.

Allowing CO2 to enter the leaf inevitably allows water to escape, and the maintenance of stomatal aperture depends on the plant's water-use economy.

With the zero K+ treatment, stomatal apertures were not affected, while K+ and Cl− guard cell concentrations fell to 30% of the control values.

However, the effects of SO2 on stomatal aperture were modulated and often overridden by environmental stresses such as low light intensity and drought.

Net photosynthetic rate was highly dependent on stomatal aperture, but nonstomatal factors also participated in the reduction of CO2 fixation.

Sulfur uptake of fumigated Ulmusamericana seedlings depended on stomatal aperture and was much higher in the light than in the dark.

The outer portions of the subsidiary cell wall is extensively thickened forming a domelike structure with a large slot opening projecting above the stomatal aperture.

For both of these reasons, RuBisCo needs high carbon dioxide concentrations, which means wide stomatal apertures and, as a consequence, high water loss.

Potassium channels and pumps have been identified and shown to function in the uptake of ions and opening of stomatal apertures (Figure 2).

The results show that not only the "stomatal resistance" but also the commonly calculated "mesophyll resistance" varies when nothing but stomatal aperture is changed.

Effects of SO2 pollution on stomatal aperture and sulfur uptake varied with SO2 dosage and plant species.

Arabidopsis was used extensively in the study of the genetic basis of phototropism, chloroplast alignment, and stomatal aperture and other blue light-influenced processes.

ABI1 is induced by abscisic acid and was shown to regulate stomatal aperture in leaves and mitotic activity in root meristems [ 33, 34].

Narrower stomatal apertures can be used in conjunction with an intermediary molecule with a high carbon dioxide affinity, PEPcase (Phosphoenolpyruvate carboxylase).

However, plants can regulate transpiration rates by altering the stomatal aperture, which changes the resistance to diffusion of water vapour from the substomatal cavity to the air surrounding the leaf.

Our results suggest that the reduction in foliage water content observed among the northern-selected genotypes is due to greater stomatal conductance at 2 C. Control of stomatal aperture is complicated.