Water uptake by roots of Hordeum marinum: formation of a barrier to radial O2 loss does not affect root hydraulic conductivity

A.J. Garthwaite, E. Steudle, Tim Colmer

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    33 Citations (Scopus)

    Abstract

    The adventitious roots of Hordeum marinum grown in stagnant deoxygenated solution contain a barrier to radial O-2 loss (ROL) in basal zones, whereas roots of plants grown in aerated solution do not. The present experiments assessed whether induction of the barrier to ROL influences root hydraulic conductivity (Lp(r)). Wheat (Triticum aestivum) was also studied since, like H. marinum, this species forms aerenchyma in stagnant conditions, but does not form a barrier to ROL. Plants were grown in either aerated or stagnant, deoxygenated nutrient solution for 21-28 d. Root-sleeving O-2 electrodes were used to assess patterns of ROL along adventitious roots, and a root-pressure probe and a pressure chamber to measure Lp(r) for individual adventitious roots and whole root systems, respectively. Lp(r), measured under a hydrostatic pressure gradient, was 1.8-fold higher for individual roots, and 5.6-fold higher for whole roots systems, in T. aestivum than H. marinum. However, there was no difference in Lp(r) between the two species when measured under an osmotic driving force, when water moved from cell to cell rather than apoplastically. Root-zone O-2 treatments during growth had no effect on Lp(r) for either species (measured in aerobic solution). It is concluded that induction of the barrier to ROL in H. marinum did not significantly affect the hydraulic conductivity of either individual adventitious roots or of the whole root system.
    Original languageEnglish
    Pages (from-to)655-664
    JournalJournal of Experimental Botany
    Volume57
    Issue number3
    DOIs
    Publication statusPublished - 2006

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