This review examines the evolution of the plant vascular system from its beginnings in the green algae to modern arborescent plants, highlighting the recent advances in developmental, organismal, geochemical and climatological research that have contributed to our understanding of the evolution of xylem. Hydraulic trade-offs in vascular structure-function are discussed in the context of canopy ...

The effect of drought on the parameters of commonly used models of plant stomatal conductance is investigated, based on a large number of data obtained at the leaf level by plant physiologists, and at the canopy level by micrometeorologists. Sixty-three case studies are analysed in order to understand the intraand inter-specific variations of the conductance and photosynthesis parameters in bot...

Betula platyphylla var. japonica (white birch) has heterophyllous leaves (i.e., early and late leaves) and is a typical pioneer tree species in northern Japan. Seedlings of white birch were exposed to ozone during two growing seasons, and measurements were carried out in the second year. Early leaves did not show an ozone-induced reduction in photosynthesis because of lower stomatal conductance...

Substantial errors can be introduced to estimates of leaf resistance (r(l)) obtained from diffusion porometers unless precautions are taken to reduce the leaf-cup temperature difference (T(leaf) - T(cup)) to acceptable levels prior to measurement. When T(leaf) > T(cup), underestimation of leaf resistance occurs; the reverse applies when T(leaf) < T(cup).The effect is most pronounced under open-...

Motivated by studies suggesting that the stomata of ferns and lycophytes do not conform to the standard active abscisic acid (ABA) -mediated stomatal control model, we examined stomatal behavior in a conifer species (Metasequoia glyptostroboides) that is phylogenetically midway between the fern and angiosperm clades. Similar to ferns, daytime stomatal closure in response to moderate water stres...

BACKGROUND AND AIMS Current understanding of stomatal development in Arabidopsis thaliana is based on mutations producing aberrant, often lethal phenotypes. The aim was to discover if naturally occurring viable phenotypes would be useful for studying stomatal development in a species that enables further molecular analysis. METHODS Natural variation in stomatal abundance of A. thaliana was ex...

For a quantitative estimate of the ozone effect on vegetation reliable models for ozone uptake through the stomata are needed. Because of the analogy of ozone uptake and transpiration it is possible to utilize measurements of water loss such as sap flow for quantification of ozone uptake. This technique was applied in three beech (Fagus sylvatica) stands in Switzerland. A canopy conductance was...

This study was conducted in order to the effect of different concentrations lead pollution on photosynthetic characteristics and growth Miscanthus floridulus, reveal its adaptability stress. The differences gas exchange parameters, chlorophyll fluorescence pigment two floridulus populations, one population from Boluo an uncontaminated site, another Dabaoshan, a mine were compared studied throug...

CO2 acts as an environmental signal that regulates stomatal movements. High CO2 concentrations reduce stomatal aperture, whereas low concentrations trigger stomatal opening. In contrast to our advanced understanding of light and drought stress responses in guard cells, the molecular mechanisms underlying stomatal CO2 sensing and signaling are largely unknown. Leaf temperature provides a conveni...