Hydrotropism in pea roots in a porous-tube water delivery system.

H. Takahashi, C. S. Brown, T. W. Dreschel, T. K. Scott

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    17 Citations (Scopus)


    Orientation of root growth on earth and under microgravity conditions can possibly be controlled by hydrotropism--growth toward a moisture source in the absence of or reduced gravitropism. A porous-tube water delivery system being used for plant growth studies is appropriate for testing this hypothesis since roots can be grown aeroponically in this system. When the roots of the agravitropic mutant pea ageotropum (Pisum sativum L.) were placed vertically in air of 91% relative humidity and 2 to 3 mm from the water-saturated porous tube placed horizontally, the roots responded hydrotropically and grew in a continuous arch along the circular surface of the tube. By contrast, normal gravitropic roots of Alaska' pea initially showed a slight transient curvature toward the tube and then resumed vertical downward growth due to gravitropism. Thus, in microgravity, normal gravitropic roots could respond to a moisture gradient as strongly as the agravitropic roots used in this study. Hydrotropism should be considered a significant factor responsible for orientation of root growth in microgravity.

    Original languageEnglish
    Pages (from-to)430-432
    Number of pages3
    JournalHortScience : a publication of the American Society for Horticultural Science
    Issue number5
    Publication statusPublished - 1992 May

    ASJC Scopus subject areas

    • Horticulture


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