Planta

, Volume 202, Issue 1, pp 43–50

Through-flow of water in leaves of a submerged plant is influenced by the apical opening

Authors

  • Ole Pedersen
    • The Freshwater Biological Laboratory, Department of Botany, University of Copenhagen, Helsingørsgade 51, DK-3400 Hillerød, Denmark
  • Lise Bolt Jørgensen
    • The Botanical Laboratory, Botanical Institute, University of Copenhagen, Gothersgade 140, DK-1153 København K., Denmark
  • Kaj Sand-Jensen
    • The Freshwater Biological Laboratory, Department of Botany, University of Copenhagen, Helsingørsgade 51, DK-3400 Hillerød, Denmark

DOI: 10.1007/s004250050101

Cite this article as:
Pedersen, O., Jørgensen, L. & Sand-Jensen, K. Planta (1997) 202: 43. doi:10.1007/s004250050101

Abstract.

Submerged aquatic higher plants maintain acropetal water transport to the young leaves in active growth to satisfy their demand for nutrients and hormones derived from the roots. We here present the first measurements of hydraulic properties for a submerged plant, the monocotyledon Sparganium emersum Rehman. The hydraulic conductance per unit length, Kh, was measured in leaf segments without the leaf tip and shown to be greater in old, fully developed leaves (1.5 · 10−10 · m4 · MPa−1 · s−1) than in young leaves (1.0 · 10−10 · m4 · MPa−1 · s−1). In leaves with intact leaf tips, however, Kh was significantly greater in the youngest leaves, which suggests that the leaf tip with the hydathode influences resistance and thus flow. Microscopy confirmed that the hydathodal area, which is an apical opening, undergoes structural changes with leaf age; a matrix of microorganisms develops in the older leaves and probably restricts water flow by clogging the hydathodes. The leaf specific conductivity expressing transport capacity relative to the leaf area supplied, of S. emersum (0.1 · 10−8 to 9 · 10−8 · m2 MPa−1· s−1) was within the same range as for various species of terrestrial ferns, vines and trees. This finding does not support the traditional concept of functionally reduced vascular transport in

Copyright information

© Springer-Verlag Berlin Heidelberg 1997