Abstract
The factors controlling root growth in hard soils are reviewed alongside summarised results from our recent studies. The turgor in cells in the elongation zone of roots pushes the apex forward, resisted by the external pressure of the soil and the tension in the cell walls. The external pressure of the soil consists of the pressure required to deform the soil, plus a component of frictional resistance between the root and soil. This frictional component is probably small due to the continuous sloughing of root cap cells forming a low-friction lining surrounding the root. Mechanically impeded roots are not only thicker, but are differently shaped, continuing to increase in diameter for a greater distance behind the root tip than in unimpeded roots. The osmotic potential decreases in mechanically impeded roots, possibly due to accumulation of solutes as a result of the slower root extension rate. This more negative osmotic potential is not always translated into increased turgor pressure, and the reasons for this require further investigation. The persistent effect of mechanical impedance on root growth is associated with both a stiffening of cell walls in the axial direction, and with a slowing of the rate of cell production.
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References
Abdalla A M, Hettiaratchi D R P and Reece A R 1969 The mechanics of root growth in granular media. J. Agric. Eng. Res. 14, 236–248.
Atwell B J 1990a The effect of soil compaction on wheat during early tillering. II. Concentrations of cell constituents. New Phytol. 115, 17–41.
Atwell B J 1990b The effect of soil compaction on wheat during early tillering. I. Growth, development and root structure. New Phytol. 115, 29–35.
Atwell B J and Newsome J C 1990 Turgor pressure in mechanically impeded lupin roots. Aust. J. Plant Physiol. 17, 49–56.
Barber D A and Gunn K B 1974 The effect of mechanical forces on the exudation of organic substances by the roots of cereal plants. New Phytol. 73, 39–45.
Barley K P 1962 The effects of mechanical stress on the growth of roots. J. Exp. Bot. 13, 95–110.
Barley K P 1963 Influence of soil strength on growth of roots. Soil Sei. 96, 175–180.
Barlow P W 1978a The ultrastructure of the regenerating root cap of Zea mays L. Ann. Bot. 42, 791–799.
Barlow P W 1978b Cell displacement through the columella of the root cap of Zea mays L. Ann. Bot. 42, 783–790.
Barlow P W 1989 Anatomical controls of root growth. Aspects Appl. Biol. 22, 57–66.
Bengough A G 1992 Penetrometer resistance equation — its derivation and the effect of soil adhesion. J. Agric. Eng. Res. 53, 163–168.
Bengough A G and Mackenzie C J 1994 Simultaneous measurement of root force and elongation for seedling pea roots. J. Exp. Bot. 45, 95–102.
Bengough A G and McKenzie B M 1997 Sloughing of root cap cells decreases the frictional resistance to maize (Zea mays L) root growth. J. Exp. Bot. (In press)
Bengough A G and Mullins C E 1991 Penetrometer resistance, root penetration resistance and root elongation rate in 2 sandy loam soils. Plant Soil 131, 59–66.
Bengough A G and Young I M 1993 Root elongation of seedling peas through layered soil of different penetration resistances. Plant Soil 149, 129–139.
Boeuf-Tremblay V, Plantureux S and Guckert A 1995 Influence of mechanical impedance on root exudation of maize seedlings at two development stages. Plant Soil 172, 279–287.
Clark L J, Whalley W R, Dexter A R, Barraclough P B and Leigh R A 1996 Complete mechanical impedance increases the turgor of cells in the apex of pea roots. Plant Cell Environ. 19, 1099–1102.
Clowes F A L 1961 Duration of a mitotic cycle in a meristem. J. Exp. Bot. 12, 283–293.
Clowes F A L 1971 The proportion of cells that divide in root meristems of Zea mays L. Ann. Bot. 35, 249–261.
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.
Croser C, Bengough AG and Pritchard J 1995a Does soil strength affect root cell production? J. Exp. Bot. 46(Suppl), 29
Croser C, Pritchard J and Bengough A G 1995b Measuring osmotic potential in single cells of mechanically impeded roots. 14th Long Ashton Int.Symp.Plant Roots - From Cells to Systems. (Abstract).
Eavis B W 1967 Mechanical impedance to root growth. Agric. Eng. Symp., Silsoe Paper 4/F/39, 1–11.
Ennos A R 1989 The mechanics of anchorage in seedlings of sunflower, Helianthus annuus L. New Phytol. 113, 185–192.
Erickson R O and Sax K B 1956 Elemental growth rate of the primary root of Zea mays. Proc. Am. Phil. Soc. 100, 487–498.
Evans H J, Neary G J and Tonkinson S M 1957 The use of colchicines as an indicator of mitotic rate in broad bean root meristems. J. Genet. 55, 487–502.
Faure A G 1994 Stress field developed by root growth: theoretical approach. J. Agric. Eng. Res. 58, 53–67.
Goss M J 1977 Effects of mechanical impedance on root growth in barley (Hordeum vulgare L.). I. Effects on the elongation and branching of seminal root axes. J. Exp. Bot. 28, 96–111.
Goss M J and Russell R S 1980 Effects of mechanical impedance on root growth in barley (Hordeum vulgare L.). III. Observation on the mechanism of response. J. Exp. Bot. 31, 577–588.
Greacen E L 1986 Root response to soil mechanical properties. Trans. 13th Cong. Int. Soc. Soil Sci. 5, 20–47.
Greacen E L, Farrell D A and Cockroft B 1968 Soil resistance to metal probes and plant roots. Trans. 9th Cong. Int. Soc. Soil Sci. 1, 769–779.
Greacen E L and Oh J S 1972 Physics of root growth. Nature, New Biol. 235, 24–25.
Green P B 1976 Growth and cell pattern formation on an axis: Critique of concepts, terminology, and modes of study. Bot. Gaz. 137, 187–202.
Groenvelt P H, Kay B D and Grant C D 1984 Physical assessment of a soil with respect to rooting potential. Geoderma 34, 101–114.
Guinel F C and McCully M E 1986 Some water-related physical properties of maize root-cap mucilage. Plant Cell Environ. 9, 657–666.
Hettiaratchi D R P and Fergusson C A 1973 Stress deformation behaviour of soil in root growth mechanics. J. Agric. Eng. Res. 18, 309–320.
MacDonald I R and Gordon D C 1984 Seedbed and related investigations. Macaulay Inst. Soil Res. Ann. Rep. 1984, 98–101
Malone M and Tomos A D 1992 Measurement of gradients of water potential in elongating pea stem by pressure probe and picolitre osmometry. J. Exp. Bot. 43, 1325–1331.
McCann M C and Roberts K 1994 Changes in cell wall architecture during cell elongation. J. Exp. Bot. 45, 1683–1691.
Misra R K, Dexter A R and Alston A M 1986 Maximum axial and radial growth pressures of plant roots. Plant Soil 95, 315–318.
Monteith J L 1986 How do crops manipulate water supply and demand? Phil. Trans. R. Soc. Lond. A 316, 245–259.
Passioura JB 1991 Soil structure and plant-growth. Aust. J. Soil Res. 29, 717–728.
Passioura J B and Fry S C 1992 Turgor and cell expansion: Beyond the Lockhart equation. Aust. J. Plant Physiol. 19, 565–576.
Pritchard J 1994 The control of cell expansion in roots. New Phytol. 127, 3–26.
Pritchard J, Barlow P W, Adams J S and Tomos A D 1990 Biophysics of the inhibition of the growth of maize roots by lowered temperature. Plant Physiol. 93, 222–230.
Pritchard J, Jones R G W and Tomos A D 1991 Turgor, growth and rheological gradients of wheat roots following osmotic-stress. J. Exp. Bot. 42, 1043–1049.
Richards B G and Greacen E L 1986 Mechanical stresses on an expanding cylindrical root analogue in granular media. Aust. J. Soil Res. 24, 393–404.
Russell R S 1977 Plant root systems. Their function and interaction with the soil. McGraw Hill, Maidenhead.
Russell R S and Goss M J 1974 Physical aspects of soil fertility — The response of roots to mechanical impedance. Neth. J. Agric. Sci. 22, 305–318.
Scholefield D and Hall D M 1985 Constricted growth of grass roots through rigid pores. Plant Soil 85, 153–162.
Silk W K, Lord E M and Eckard K J 1989 Growth patterns inferred from anatomical records. Plant Physiol. 90, 708–713.
Stolzy L H and Barley K P 1968 Mechanical resistance encountered by roots entering compact soils. Soil Sci. 105, 297–301.
Taylor H M and Ratliff L H 1969 Root elongation rates of cotton and peanuts as a function of soil strength and water content. Soil Sci. 108, 113–119.
Veen B W 1982 The influence of mechanical impedance on the growth of maize roots. Plant Soil 66, 101–109.
Voorhees W B, Farrell D A and Larson W E 1975 Soil strength and aeration effects of root elongation. Soil Sci. Soc. Am. Proc. 39, 948–953.
Whiteley G M, Hewitt J S and Dexter A R 1982 The buckling of plant roots. Physiol. Plant 54, 333–342.
Whiteley G M, Utomo W H and Dexter A R 1981 A comparison of penetrometer pressures and the pressures exerted by roots. Plant Soil 61, 351–364.
Wiersum L K 1957 The relationship of the size and structural rigidity of pores to their penetration by roots. Plant Soil 9, 75–85.
Wilson A J, Robards A W and Goss M J 1977 Effects of mechanical impedance on root growth in barley, Hordeum vulgare L. II. Effects on cell development in seminal roots. J. Exp. Bot. 28, 1216–1227.
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Bengough, A.G., Croser, C., Pritchard, J. (1997). A biophysical analysis of root growth under mechanical stress. In: Anderson, H.M., Barlow, P.W., Clarkson, D.T., Jackson, M.B., Shewry, P.R. (eds) Plant Roots - From Cells to Systems. Developments in Plant and Soil Sciences, vol 73. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-5696-7_11
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