Oscillations in stomatal conductance in the light and dark.



Oscillations in stomatal conductance of hybrid poplar leaves in the light and dark.

by Reich P. B. (1984)

Peter B. Reich

in Plant Physiology 1984;61:541-548 –DOI: 10.1111/j.1399-3054.1984.tb05167.x –

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Cycling of stomatal conductance in three hybrid poplar (Populus sp.) cultivars was observed under a variety of conditions. Illumination of plants kept previously in the dark induced very large oscillations with a period of about 40 min and large oscillations with a shorter period (< 10 min) were superimposed on the longer cycles. During these oscillations, large changes in conductance could occur very rapidly (1.0 cm s−1 in 3 min).

Plants in constant light also displayed both long and short term cycles in conductance, but these were smaller in amplitude than those induced by sudden illumination.

Stomatal oscillations were also observed in darkness and after darkening of previously illuminated plants. These oscillations had shorter (< 30 min) and less regular periods than those observed in the light. Such cycling in the dark is rare.

Cycling of the two leaf surfaces was sometimes in synchrony in the light, and more so after a perturbation. Little synchrony between the two surfaces was observed in the dark.

Stomatal movements of different leaves on a plant were usually relatively independent. Transient stomatal opening occurred following leaf excision in the light or dark, and often after sudden darkening of intact leaves. Also, stomata of intact leaves sometimes transiently closed following illumination.

Stomatal density, diffusive conductance and stomatal responses



Leaf stomatal density and diffusive conductance in three amphistomatous hybrid poplar cultivars.

by Reich P. B. (1984)

Peter B. Reich

in New Phytologist 98 (2): 231-239 –DOI: 10.1111/j.1469-8137.1984.tb02733.x  –

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Stomatal density and diffusive conductance were characterized for both leaf surfaces in three amphistomatous hybrid cultivars of poplar. Consistent differences in stomatal density were observed between cultivars and between leaf surfaces within a cultivar.

Mean stomatal density in the three cultivars ranged from 150 to 330 stomata mm−2 for abaxial leaf surfaces and from 75 to 100 stomata mm−2 for adaxial surfaces. The density of stomata on the abaxial versus adaxial surface was related to the spatial orientation of leaves with respect to the horizon and this stomatal ratio ranged from 1–4 to 4–0 in the three clones. Also, stomatal density was greater in leaves at higher rather than lower nodal positions.

Differences in diffusive conductance between cultivars and leaf surfaces were observed on intact and detached leaves in the light and dark. Within each cultivar mean abaxial conductance (Kab) was greater than adaxial conductance (Kad).

Mean conductances in the light for the three cultivars ranged from 0–22 to 0–62 cm s−1 for abaxial, and from 0–15 to 0–17 cm s−1 for adaxial surfaces, and in the dark they were between 0.06 and 0.26 cm s−1 for abaxial, and from 0–04 to 0–06 for adaxial surfaces.

The differences in conductance between cultivars and between leaf surfaces were correlated with their respective stomatal densities.

Stomatal response to light and to leaf excision also varied between cultivars and between the two leaf surfaces.