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- 3Hydraulic conductivity
- 3Xylem cavitation
- 2Basal angiosperm physiology
- 2Ecological wood anatomy
We tested two hypotheses for how vessel evolution in angiosperms influenced xylem function. First, the transition to vessels decreased resistance to flow-often considered the driving force for their evolution. Second, the transition to vessels compromised safety from cavitation-a constraint...
Weak tradeoff between xylem safety and xylemspecific hydraulic efficiency across the world’s woody plant speciesDownload
Maherali, H., Cao, K-.F., Schreiber, S.G., Brodribb, T.J., Westoby, M., Hacke, U.G., Jacobsen, A.L., Lens, F., Choat, B., Wright, I.J., Pittermann, J., Gleason, S., Bhaskar, R., Nardini, A., Morris, H., Mayr, S., Bucci, S.J., Mencuccini, M., Johnson, D.M., Mitchell, P.J., Fan, Z-.X., Sperry, J.S., Delzon, S., Zanne, A.E., Martínez-Vilalta, J., Cochard, H., Plavcová, L., McCulloh, K.A., Jansen, S., Domec, J-.C., Pratt, R.B., Feild, T.S.
The evolution of lignified xylem allowed for the efficient transport of water under tension, but also exposed the vascular network to the risk of gas emboli and the spread of gas between xylem conduits, thus impeding sap transport to the leaves. A well-known hypothesis proposes that the safety of...
Two structure-function hypotheses were tested for vesselless angiosperm wood. First, vesselless angiosperm wood should have much higher flow resistance than conifer wood because angiosperm tracheids lack low-resistance torus-margo pits. Second, vesselless wood ought to be exceptionally safe from...
Pit membrane structure is highly variable and accounts for a major resistance to water flow through tracheid pits in stems and roots of two boreal conifer speciesDownload
The flow of xylem sap in conifers is strongly dependent on the presence of a low resistance path through bordered pits, particularly through the pores present in the margo of the pit membrane. A computational fluid dynamics approach was taken, solving the Navier–Stokes equation for models based...
Evaluation of centrifugal methods for measuring xylem cavitation in conifers, diffuse and ringporous angiospermsDownload
• A centrifugal method is used to measure ‘vulnerability curves’ which show the loss of hydraulic conductivity in xylem by cavitation. Until recently, conductivity was measured between bouts of centrifugation using a gravity-induced head. Now, conductivity can be measured during centrifugation....
The standard centrifuge method accurately measures vulnerability curves of longvesselled olive stemsDownload
The standard centrifuge method has been frequently used to measure vulnerability to xylem cavitation. This method has recently been questioned. It was hypothesized that open vessels lead to exponential vulnerability curves, which were thought to be indicative of measurement artifact. We tested...
Heterogeneous distribution of pectin epitopes and calcium in different pit types of four angiosperm speciesDownload
Intervessel pits act as safety valves that prevent the spread of xylem embolism. Pectin–calcium crosslinks within the pit membrane have been proposed to affect xylem vulnerability to cavitation. However, as the chemical composition of pit membranes is poorly understood, this hypothesis has not...
• While tracheid size of conifers is often a good proxy of water transport efficiency, correlations between conifer wood structure and transport safety remain poorly understood. It is hypothesized that at least some of the variation in bordered pit and tracheid structure is associated with both...