Growth of tree roots in hostile soil: a comparison of root growth pressures of tree seedlings with peas

Azam, Gausul and Grant, Cameron D. and Misra, Rabindra K. and Murray, Robert S. and Nuberg, Ian K. (2013) Growth of tree roots in hostile soil: a comparison of root growth pressures of tree seedlings with peas. Plant and Soil: international journal on plant-soil relationships, 368 (1-2). pp. 569-580. ISSN 0032-079X


Background and Aims: As part of a study on growth of tree roots in hostile soil, we envisaged that establishment and survival of trees on hard, dry soil may depend on their ability to exert axial root growth pressures of similar magnitude to those of the roots of agricultural plants (with significant root thickening when roots grow across an air gap or cracks and biopores). We selected tree species originating from a range of different soil and climatic conditions to evaluate whether their relative success on harsh soil (in an evolutionary sense) might be related to the magnitude of root growth pressures they could exert, or how they performed in the very early stages of growth after germination.
Methods: We measured the maximum axial root growth force (Fmax) on single lateral root axes of 3- to 4- month old seedlings of 6 small-seeded eucalypts from 2 different habitats and 2 contrasting soil types. Root growth rate, root diameter and Fmax were also measured on the primary root axes of a large-seeded acacia and a domesticated annual (Pisum sativum) seedling for up to 10 days following germination.
Results: The lateral roots of the 6 eucalypts and the primary roots of the acacia were considerably smaller than the primary roots of P. sativum and they exerted average forces of similar magnitude to one another (0.198 to 0.312 N). The maximum axial root growth pressures were all in the range 150 to 250 kPa but E. leucoxylon, E. loxophleba and A. salicina exerted the greatest pressures among the trees, and comparable pressures to those exerted by the primary roots of 2-day-old P. sativum (211-252 kPa). Although the primary roots of acacia seedlings exerted increasing axial root growth pressures over a 10-day period following germination, the pressures were still only slightly greater than those of the domesticated plant, P. sativum. Conclusions: The lack of any very large differences in axial root growth pressures between trees and domesticated plants suggests that trees that grow well in harsh soil don't do so by exerting higher root growth pressures alone but by also exploring the network of cracks and pores more effectively than do other plants that are less successful.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2012 Springer Science+Business Media Dordrecht. Published version deposited in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Date Deposited: 10 Jul 2013 05:19
Last Modified: 05 Feb 2018 06:28
Uncontrolled Keywords: root elongation; hard soil; root growth force; woody perennials; annual crops; Pisum sativum; eucalypt; acacia; plant evolution
Fields of Research : 05 Environmental Sciences > 0503 Soil Sciences > 050305 Soil Physics
06 Biological Sciences > 0607 Plant Biology > 060799 Plant Biology not elsewhere classified
07 Agricultural and Veterinary Sciences > 0705 Forestry Sciences > 070501 Agroforestry
Socio-Economic Objective: D Environment > 96 Environment > 9605 Ecosystem Assessment and Management > 960505 Ecosystem Assessment and Management of Forest and Woodlands Environments
D Environment > 96 Environment > 9609 Land and Water Management > 960906 Forest and Woodlands Land Management
Identification Number or DOI: 10.1007/s11104-012-1537-4

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