Plant and Soil

, Volume 165, Issue 2, pp 293–300 | Cite as

Root movements: Towards an understanding through attempts to model the processes involved

  • Peter W. Barlow
  • Hanna E. Zieschang
Article

Abstract

Roots have the ability to change the direction of their forward growth. Sometimes these directional changes are rapid, as in mutations, or they are slower, as in tropisms. The gravitational force is always present and roots have an efficient graviperception mechanism which enables them to initiate gravitropic movements. In trying to model and simulate the course of gravitropic root movements with a view to analyse the component processes, the following aspects of the plant's interaction with gravity have been considered: (1) The level of organization (organism, organ, cell) at which the movement process is expressed; (2) whether the gravity stimulation event is dynamic or static (i.e. whether or not physiologically significant displacements take place with respect to the gravity vector); (3) the sub-systems involved in movement and the processes which they regulate; (4) the mathematical characterization of the relevant sub-systems. A further allied topic is the nature of nutational movements and whether they are linked with gravitropic movements in some way. In considering how they can best be modelled, two types of nutational movements are proponed: stochastic nutation and circumnutation. Most, if not all, natural movements developed in response to static gravistimulation can be viewed as gravimorphisms. This applies at the levels of cell, organ and organism. However, when a system at any one of these levels experiences dynamic gravistimulation, because of its inherent homeostatic properties, it is induced to regenerate a state similar to that previously held. Thus, gravitropism is a regenerative gravimorphic process at the level of the organ.

Key words

gravitropism living systems theory nutation Phleum pratense L. simulation Zea mays 

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Copyright information

© Kluwer Academic Publishers 1994

Authors and Affiliations

  • Peter W. Barlow
    • 1
    • 2
  • Hanna E. Zieschang
    • 1
    • 2
  1. 1.Department of Agricultural SciencesUniversity of Bristol, Institute of Arable Crops Research, Long Ashton Research StationBristolUK
  2. 2.Botanisches Institut der Universitat BonnBonnGermany

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