Summary
A model is developed for the rate of elongation of a root tip in terms of the balance of pressures acting on the root. Differentials of this equation give expressions for the changes in root elongation rate with respect to soil water potential and soil mechanical resistance. The model predicts that root cells osmoregulate against both water stress and soil mechanical resistance with predicts that root cells osmoregulate against both water stress and soil mechanical resistance with similar efficiencies which are less than 100%. Analysis of published data leads to the conclusion that root tips of pea osmoregulate with 70% efficiency. A working equation is developed for the elongation rate of roots in conditions of combined water stress and mechanical resistance.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Barley K P 1968 Deformation of the soil by the growth of plants. Trans. 9th. Int. Cong. Soil Sci. 1, 759–768. Angus and Robertson, Sydney.
Cockroft B, Barley K P and Greacen E L 1969 The penetration of clays by fine probes and root tips. Aust. J. Soil Res. 7, 333–348.
Collis-George N and Yoganathan O 1985 The effect of soil strength on germination and emergence of wheat (Triticum aestivum L.) II. High shear strength conditions. Aust. J. Soil Res. 23, 589–601.
Eavis B W and Payne D 1968 Soil physical conditions and root growth.In Root Growth. Ed. W J Whittington. Butterworths, London, 315–341.
Eavis B W, Ratliff L and Taylor H M 1969 Use of a dead-load technique to determine axial root growth pressure. Agron. J. 61, 640–643.
Gill W R and Bolt G H 1955 Pfeffer's studies of the root growth pressures exerted by plants. Agron. J. 166–168.
Gooderham P T 1973 Soil Physical Conditions and Plant Growth, Ph. D. thesis, Univ. Reading.
Greacen E L, Farrell D A and Cockroft B 1968 Soil resistance to metal probes and plant roots. Trans. 9th. Int. Cong. Soil Sci. 1, 769–779. Angus and Robertson, Sydney.
Greacen e L and Oh J S 1972 Physics of root growth. Nature New Biology 235, 24–25.
Green P B 1968 Growth Physics in Nitella: a method for continuous in vivo analysis of extensibility based on a micro-manometer technique for turgor pressure. Plant Physiol. 43, 1169–1184.
Green P B, Erickson R O and Buggy H 1971 Metabolic and physical control of cell elongation rate. Plant Physiol. 47, 423–430.
Hewitt J S and Dexter A R 1984 The behavior of roots encountering cracks in soil. Plant and Soil 79, 11–28.
Mirreh H F and Ketcheson J W 1973 Influence of soil water matric potential and resistance to penetration on corn root elongation. Can. J. Soil Sci. 53, 383–388.
Misra R K, Dexter A R and Alston A M 1986 Penetration of soil aggregates of finite size. II. Plant roots. Plant and Soil 94, 59–85.
Misra R K, Dexter A R and Alston A M 1986. Maximum axial and radial growth pressures of plant roots. Plant and Soil 95, 315–326.
Pfeffer W 1893 Druck und Arbeitsleistung durch Wachsende Pflanzen. Abhandlungen der Koniglich Sachsischen Gesellschaft der Wissenschaften 33, 235–474.
Richards B G and Greacen E L 1986 Mechanical stress on a root growing in granular media. Aust. J. Soil Res. 24, 393–404.
Taylor H M and Ratliff L F 1969 Root elongation rates of cotton and peanuts as a function soil strength and soil water content. Soil Sci. 108, 113–119.
Taylor H M and Ratliff L F 1969 Root growth pressures of cotton, peas and peanuts. Agron. J. 61, 398–402.
Whiteley G M, Utomo W H and Dexter A R 1981 A comparison of penetrometer pressures and the pressures exerted by roots. Plant and Soil 61, 351–364.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Dexter, A.R. Mechanics of root growth. Plant Soil 98, 303–312 (1987). https://doi.org/10.1007/BF02378351
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF02378351