BACKGROUND AND AIMS Daytime root-zone temperature may be a significant factor regulating water flux through plants. Water flux can also occur during the night but nocturnal stomatal response to environmental drivers such as root-zone temperature remains largely unknown. METHODS Here nocturnal and daytime leaf gas exchange was quantified in 'Shiraz' grapevines (Vitis vinifera) exposed to three...

In order to evaluate factors controlling transpiration of six common eastern deciduous species in North America, a model describing responses of canopy stomatal conductance (GS) to net radiation (RN), vapor pressure deficit (D) and relative extractable soil water (REW) was parameterized from sap flux data. Sap flux was measured in 24 mature trees consisting of the species Carya tomentosa, Querc...

Transpiration of two heterogeneous broad-leaved woodlands in southern England was monitored by the sap flux technique throughout the 2006 growing season. Grimsbury Wood, which had a leaf area index (LAI) of 3.9, was dominated by oak (Quercus robur L.) and birch (Betula pubescens L.) and had a continuous hazel (Corylus avellana L.) understory. Wytham Woods, which had an LAI of 3.6, was dominated...

carbon dioxide (CO2) assimilation, and transpiration in a Larix gmelinii (Rupr.) Rupr. ex Kuzen forest in eastern Siberia. At the CO2 concentration of ambient air, maximum values (mean of 10 highest measured values) for CO2 assimilation, transpiration and leaf conductance for water vapor were 10.1 μmol m s, 3.9 mmol m s and 365 mmol m s, respectively. The corresponding mean values, which were m...

Land-surface models use different formulations of stomatal conductance and plant hydraulics, and it is unclear which type of model best matches the observed surface-atmosphere water flux. We use the North American Carbon Program data set of latent heat flux (LE) measurements from 25 sites and predictions from 9 models to evaluate models’ ability to resolve subdaily dynamics of transpiration. De...

Results from the 14 land surface parameterization schemes involved in the PILPS-RICE Workshop are compared for a soya crop growing season (from June to September). During this period, the transpiration flux dominates the total surface evapotranspiration and observed data from HAPEX-MOBILHY are available for comparison. Results indicate that during the month of June half of the models fall withi...

In current European risk assessment, an equilibrium approach is used to estimate chemical uptake from soil into root vegetables. Here a dynamic model for uptake of neutral lipophilic compounds from soil into roots is presented. Using experimental results, it is compared with the equilibrium approach. Very lipophilic compounds (e.g., DDT) diffuse very slowly into plant tissue, so they are likely...

Plants with citrus variegated chlorosis (CVC), a disease caused by the xylem-limited bacteria Xylella fastidiosa, have leaves with water deficiency symptoms and are associated with decreases on the net photosynthesis and transpiration rates. Using healthy and CVC-affected ‘Pêra’ sweet orange plants on ‘Rangpur’ lime rootstock, the leaf gas exchange variables were measured with an open-gas porta...

In this study, artificial neural network analyses (ANN) were used to identify the forcing environmental variables that are most significant in governing the transpiration rates of an Austrian Pine stand and its forest floor. Latent heat flux densities (Lh) of the Austrian Pine stand and its forest floor were separately measured using the eddy covariance technique. To assess the sensitivity of t...