%0 Journal Article %1 Cochardetal_04 %A Cochard, H. %A Nardini, A. %A Coll, L. %D 2004 %J Plant, Cell and Environment %K bibtex-import, citeulikeExport hydraulics, kleaf, techniques %P 1257--1267 %T Hydraulic architecture of leaf blades: where is the main resistance? %V 27 %X The hydraulic architecture of Laurus nobilis L. and Juglans regia L. leaves was studied using three different approaches: (1) hydraulic measurements of both intact leaves and of leaves subjected to treatments aimed at removing the extra-vascular resistance; (2) direct measure- ments of the vascular pressure with a pressure probe; and (3) modelling the hydraulic architecture of leaf venation system on the basis of measurements of vein densities and conductivities. The hydraulic resistance of leaves (Rleaf) either cut, boiled or frozen?thawed was reduced by about 60 and 85\% with respect to control leaves for laurel and walnut, respectively. Direct pressure drop measurements suggested that 88\% of the resistance resided outside the vascular system in walnut. Model simulations were in agreement with these results provided vein hydraulic con- ductance was 0.12?0.28 that of the conductance predicted by Poiseuille?s law. The results suggest that Rleaf is domi- nated by substantial extra-vascular resistances and there- fore contrast with the conclusions of recent studies dealing with the hydraulic architecture of the leaf. The present study con?rms the ?classical? view of the hydraulic architec- ture of leaves as composed by a low-resistance component (the venation) and a high-resistance component (the mesophyll).

@article{Cochardetal_04, abstract = {{The hydraulic architecture of Laurus nobilis L. and Juglans regia L. leaves was studied using three different approaches: (1) hydraulic measurements of both intact leaves and of leaves subjected to treatments aimed at removing the extra-vascular resistance; (2) direct measure- ments of the vascular pressure with a pressure probe; and (3) modelling the hydraulic architecture of leaf venation system on the basis of measurements of vein densities and conductivities. The hydraulic resistance of leaves (Rleaf) either cut, boiled or frozen?thawed was reduced by about 60 and 85\% with respect to control leaves for laurel and walnut, respectively. Direct pressure drop measurements suggested that 88\% of the resistance resided outside the vascular system in walnut. Model simulations were in agreement with these results provided vein hydraulic con- ductance was 0.12?0.28 that of the conductance predicted by Poiseuille?s law. The results suggest that Rleaf is domi- nated by substantial extra-vascular resistances and there- fore contrast with the conclusions of recent studies dealing with the hydraulic architecture of the leaf. The present study con?rms the ?classical? view of the hydraulic architec- ture of leaves as composed by a low-resistance component (the venation) and a high-resistance component (the mesophyll).}}, added-at = {2019-03-31T01:14:40.000+0100}, author = {Cochard, H. and Nardini, A. and Coll, L.}, biburl = {https://www.bibsonomy.org/bibtex/2161f4e571917b109104acfc2ee4f63fa/dianella}, citeulike-article-id = {1523653}, comment = {(private-note)More recently (Tyree, Nardini \& Salleo 2001; Salleo et al. 2003), freezing treat- ments aimed at disrupting cell membranes have revealed that at least 50?80\% of the leaf hydraulic resistance is located outside the venous system. This ?nding would be in agreement with the impact of vein cavitation on leaf hydraulics which, in many cases, has been found to be less than expected on the basis of countings of ultrasound acoustic emissions and ***visual observations of the function- ality of leaf veins (Nardini, Tyree \& Salleo 2001; Nardini, Salleo \& Raimondo 2003; Salleo et al. 2003; Tri?l\"{i}¿½et al. 2003). READ ...BUT people have found a large pressure dissipation between the main veins and the minor veins which ought to indicate that the resistance of those minor veins is a significant component of leaf resistance. isn't it cheating a bit, having a fudge factor and saying "the model agrees with reality if efficiency is X" the model wasn't very sensitive to minor veins, but it was sensitive to a 0.5\% drop in efficiency of first and second order veins, so I thik I'm alright. Cite this one for your justification of sumr4 differences and how it might affect foliosa The problem with Sack and Zwieniecki et al's work might be that their leaves weren't in equilibrium with the pressure probe yet (?). The problem with this work is that freezing/boiling the leaves my disrupt the bundle sheath... It has to be pointed out that boiling and freezing leaves might increase the radial permeability of major veins by disrupting bundle sheath cells, thus short-circuiting the water ?ow through the venation system and leading to underestimation of the con- tribution of the vein network to leaf hydraulic resistance. This all has big implications for how much of an effect embolism has on leaf water supply. (would be buffered if the veins weren't the sites of resistance)}, interhash = {75074a8c60d77947481e76564158bf75}, intrahash = {161f4e571917b109104acfc2ee4f63fa}, journal = {Plant, Cell and Environment}, keywords = {bibtex-import, citeulikeExport hydraulics, kleaf, techniques}, pages = {1257--1267}, posted-at = {2007-07-31 06:12:43}, priority = {0}, timestamp = {2019-03-31T01:16:26.000+0100}, title = {{Hydraulic architecture of leaf blades: where is the main resistance?}}, volume = 27, year = 2004 }