Submitted to: American Society of Agronomy Monograph Series
Publication Type: Book / Chapter
Publication Acceptance Date: July 30, 2004
Publication Date: November 7, 2005
Citation: Zobel, R.W. 2005. Tertiary Root Systems. In: Zobel, R.W. and Wright, S.A. American Society of Agronomy Monograph Series 48. Agronomy Society of America, Madison, Wisconsin. p 35-56. Technical Abstract: The currently active root research paradigm is: Differences in root function are due to differences in surface area to volume (biomass) ratios. Root research undertaken with this paradigm in mind has been only marginally successful. A new working hypothesis is proposed: 'A plant root system is composed of a coordinated set of genetically and functionally distinct classes of root'. This hypothesis is supported by three demonstrable postulates, the third of which is discussed in this paper: The tertiary root system is made up of two or more classes of genetically and functionally distinct root, smaller than 0.6 mm diameter that condition the observed functionality of mature root systems. This paper summarizes the existing evidence for this postulate and discusses the implications for root system rapid response to environmental perturbations.