Water flux in a young, 4-year old, cashew (Anacardium occidentale L.) plantation was studied over a dry season, from November 2001 to March 2002, in the forest-savannah transition zone of Ghana, West Africa. The temperature-difference method was used over this five-month period to quantify the diurnal and day-to-day whole-tree sap flow (Qt) and hence the canopy scale transpiration (Ec). M...

expansion of apple growing to dry areas requires reliable approaches to select genotypes tolerant to water stress. we have simulated apple tree transpiration (ec) from different commercial orchards and compared it with actual transpiration (ea) derived from sap flow measurements. the modelling approach lies in rearranging a parameterized p–m equation and incorporating in it a stomatal conductan...

Sap flow measurements provide a powerful tool for quantifying plant water use and monitoring qualitative physiological responses of plants to environmental conditions. As such, sap flow methods are widely employed to investigate the agronomic, ecological, and hydrological outcomes of plant growth. The following summary provides an overview of thermodynamic sap flow measurement techniques used t...

Calibration of the Granier thermal dissipation technique for measuring stem sap flow in trees requires determination of the temperature difference (DeltaT) between a heated and an unheated probe when sap flow is zero (DeltaT(max)). Classically, DeltaT(max) has been estimated from the maximum predawn DeltaT, assuming that sap flow is negligible at nighttime. However, because sap flow may continu...

During the night, plant water loss can occur either through the roots, as hydraulic redistribution (HR), or through the leaves via the stoma, as nocturnal transpiration (En), which was methodologically difficult to separate from stem refilling (Re). While HR and En have been reported across a range of species, ecosystem, and climate zone, there is little understanding on the interactions betwee...

The magnitude and direction of water transport by the roots of eight dominant Brazilian savanna (Cerrado) woody species were determined with a heat pulse system that allowed bidirectional measurements of sap flow. The patterns of sap flow observed during the dry season in species with dimorphic root systems were consistent with the occurrence of hydraulic redistribution of soil water, the movem...

When soil moisture is heterogeneous, sap flow from, and ABA status of, different parts of the root system impact on leaf xylem ABA concentration ([X-ABA]leaf). The robustness of a model for predicting [X-ABA]leaf was assessed. 'Two root-one shoot' grafted sunflower (Helianthus annuus L.) plants received either deficit irrigation (DI, each root system received the same irrigation volumes) or par...

Transient responses of sap flow to step changes in wind speed were experimentally investigated in a wind tunnel. A Granier-type sap flow sensor was calibrated and tested in a cylindrical tube for analysis of its transient time response. Then the sensor was used to measure the transient response of a well-watered Pachira macrocarpa plant to wind speed variations. The transient response of sap fl...

Knowledge of sap flow variability in tree trunks is important for up-scaling transpiration from the measuring point to the whole-tree and stand levels. Natural variability in sap flow, both radial and circumferential, was studied in the trunks and branches of mature olive trees (Olea europea L., cv Coratina) by the heat field deformation method using multi-point sensors. Sapwood depth ranged fr...