Hydraulic architecture of leaf venation in Laurus nobilis L.

Veins are the main irrigation system of the leaf lamina and an understanding of the hydraulic architecture of the vein networks is essential for understanding leaf function. However, determination of leaf hydraulic parameters is challenging, because for most leaves the vein system is reticulate, contains a hierarchy of different vein sizes, and consists of leaky conduits. We present a new approach that allows for measurements of pressure differences between the petiole and any vein within the leaf. Measurements of Laurus nobilis leaves indicate that first- and second-order veins have high axial conductance and relatively small radial permeability, thus allowing water to reach distal areas of the leaf with only a small loss of water potential. Higher order veins tend to be more hydraulically resistant and permit greater radial leakage. This design allows for a relatively equitable distribution of water potential and thus reflects the capacity of the venation to provide a relatively homogeneous water supply across the leaf lamina, with only the leaf margins being hydraulically disadvantaged relative to the rest of the leaf.

[1]  A. Knoll,et al.  Evolution of developmental potential and the multiple independent origins of leaves in Paleozoic vascular plants , 2002, Paleobiology.

[2]  A. Sõber,et al.  Leaf anatomical characteristics associated with shoot hydraulic conductance, stomatal conductance and stomatal sensitivity to changes of leaf water status in temperate deciduous trees , 2001 .

[3]  J. Camarero,et al.  Relationship between hydraulic resistance and leaf morphology in broadleaf Quercus species: a new interpretation of leaf lobation , 2001, Trees.

[4]  V. Mosbrugger,et al.  Evolution and Function of Leaf Venation Architecture: A Review , 2001 .

[5]  A Nardini,et al.  Xylem cavitation in the leaf of Prunus laurocerasus and its impact on leaf hydraulics. , 2001, Plant physiology.

[6]  A. Nardini,et al.  Limitation of stomatal conductance by hydraulic traits: sensing or preventing xylem cavitation? , 2000, Trees.

[7]  J. Durand,et al.  Changes in axial hydraulic conductivity along elongating leaf blades in relation to xylem maturation in tall fescue. , 2000, The New phytologist.

[8]  N. Holbrook,et al.  Dynamic changes in petiole specific conductivity in red maple (Acer rubrum L.), tulip tree (Liriodendron tulipifera L.) and northern fox grape (Vitis labrusca L.) , 2000 .

[9]  Karl J. Niklas,et al.  A mechanical perspective on foliage leaf form and function , 1999 .

[10]  P. Becker,et al.  Hydraulic conductances of angiosperms versus conifers: similar transport sufficiency at the whole-plant level. , 1999, Tree physiology.

[11]  I. R. Cowan,et al.  A study of stomatal mechanics using the cell pressure probe , 1998 .

[12]  T. Nelson,et al.  Leaf Vascular Pattern Formation. , 1997, The Plant cell.

[13]  Andrea Nardini,et al.  Is sclerophylly of Mediterranean evergreens an adaptation to drought , 1997 .

[14]  M. Canny.  Apoplastic Water and Solute Movement: New Rules for an Old Space , 1995 .

[15]  Melvin T. Tyree,et al.  Hydraulic architecture of Acer saccharum and A. rubrum: comparison of branches to whole trees and the contribution of leaves to hydraulic resistance , 1994 .

[16]  Richard H. Cuenca,et al.  Irrigation System Design: An Engineering Approach , 1989 .

[17]  A. Specht,et al.  Canopy structure in Eucalyptus-dominated communities in Australia along climatic gradients , 1989 .

[18]  H. Marschner.  Mineral Nutrition of Higher Plants , 1988 .

[19]  A. Jeje.  The flow and dispersion of water in the vascular network of dicotyledonous leaves. , 1985, Biorheology.

[20]  Joe Landsberg,et al.  Water Movement Through Plant Roots , 1978 .

[21]  A. ALLSOPP,et al.  Plant Anatomy , 1966, Nature.