Reduction of hydraulic conductance to the canopy has been shown to result in stomatal responses to limit transpiration. To test for similar responses to perturbations of the hydraulic network in leaves, we simultaneously measured leaf gas exchange with spatially explicit chlorophyll-a fluorescence and leaf temperature to examine the effects of cutting a primary leaf vein in Helianthus annuus. W...

water use efficiency (wue, the ratio of total dry matter to water use) became a breeding target only when it was found that carbon stable isotopes were inversely related to wue. the current study conducted under well-watered and drought conditions in the field over two years at broom’s barn research station, uk, was undertaken to investigate the extent of genotypic differences for water use, yi...

determination of chlorophyll content and chlorophyll fluorescence has the potential needed to analyze the efficiency of photosynthesis in plants against environmental stresses, especially salinity, and its simplicity facilitates stress evaluation. in order to study the response of different photosynthetic characters to salinity stress at different sugar beet growth stages, two separate experime...

Leaf conductance, water relations, growth, and abscisic acid (ABA) concentrations in xylem sap, root apices and leaves were assessed in oak seedlings (Quercus robur L.) grown with a root system divided between two compartments and subjected to one of four treatments: (a) well watered, WW; (b) half of root system exposed to soil drying and half kept well watered, WD; (c) whole root system expose...

Leaf hydraulic conductance (K leaf) is a major determinant of photosynthetic rate in plants. Previous work has assessed the relationships between leaf morpho-anatomical traits and K leaf with woody species, but there has been very little focus on cereal crops. The genus Oryza, which includes rice (Oryza sativa) and wild species (such as O. rufipogon cv. Griff), is ideal material for identifying...

The hypothesis of optimal stomatal conductance predicts conductance should vary with changes of the vapor pressure difference between leaf and air (VPD) to keep the partial derivative of transpiration rate (E) with respect to assimilation rate (A) constant ( partial differentialE/ partial differentialA = lambda). Stomatal conductance of Amaranthus powellii Wats. decreased strongly with increasi...

Different spatial distributions of soil moisture were imposed on field-grown grapevines by applying the same irrigation volumes to the entire (DI; deficit irrigation) or part of the (PRD; partial root zone drying) root zone. Five treatments were applied: controls irrigated at 60% ETc (crop evapotranspiration) for the whole season (308 mm year(-1)); DI-1 and PRD-1 that received the same irrigati...

Terrestrial ecosystems are dominated by vascular plants that form a mosaic of hydraulic conduits to water movement from the soil to the atmosphere. Together with canopy leaf area, canopy stomatal conductance regulates plant water use and thereby photosynthesis and growth. Although stomatal conductance is coordinated with plant hydraulic conductance, governing relationships across species has no...

Most methods of measuring the diffusive conductance to water vapor of individual plant leaves potentially change the leaf environment by enclosing part of the leaf in order to measure the rate of water vapor exchange and the driving force for that exchange. There have been questions about whether leaf to air water vapor pressure difference varies sufficiently in extensive crop canopies to be a ...

Xylella fastidiosa, a xylem-limited bacterial pathogen that causes bacterial leaf scorch in its hosts, has a diverse and extensive host range among plant species worldwide. Previous work has shown that water stress enhances leaf scorch symptom severity and progression along the stem in Parthenocissus quinquefolia infected by X. fastidiosa. The objective here was to investigate the mechanisms un...