A New Method for the Determination of Osmotic Pressure

Lockhart, James A.

doi:10.1002/j.1537-2197.1959.tb07074.x

Cited by 9 publications

(5 citation statements)

References 8 publications

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“…This first region is divided by an apparently sharp inflection point from the second region in which diameter decreases rapidly with increasing stress. This response of root diameter to water stress is similar to that shown by Lockhart (1959) for the deformability of young plant stems, and for which the point of sharp inflection was again indicative of the point of limiting plasmolysis.…”

Section: Effects Of Water Stresssupporting

confidence: 78%

Elastic response of the roots of field crops

Whiteley

Dexter

1981

Physiologia Plantarum

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The elasticity of root tips was investigated in experiments of the static clamped‐beam type. The response was non‐linear. The results were interpreted in terms of a generalized elastic modulus M, and two parameters, α and β, which account for the non‐linearity. Seminal axes and primary lateral roots of 16 crop species grown in the laboratory show significant inter‐species differences but insignificant inter‐variety differences in the elastic properties. A smaller set of results for field‐grown roots with two tillage treatments shows that, in nearly all cases, the elastic modulus is smaller and the diameter is larger than with laboratory‐grown roots. Environmental factors such as water potential, and nutrition have significant influences on the diameters and elastic behaviour of roots.

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Section: Effects Of Water Stresssupporting

confidence: 78%

Elastic response of the roots of field crops

Whiteley

Dexter

1981

Physiologia Plantarum

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“…For sunflower this is known to be 1500 kPa . Estimated maximum root growth pressures (Oniax) for sunflower (Veihmeyer and Hetidrickson 1949), and for pea, safflower and wheat using a modified method of Lockhart (1959). Critical root length (/J at which a,, = a"^" and root cHameter d for roots growing across a 3 mm air gap.…”

Section: Roots In Narrow Air Gaps (L< 3 Mm)mentioning

confidence: 99%

“…drickson 1949). In addition, the osmotic potential can be estimated fairly reliably by the method of Lockhart (1959) for the root types used in the water stress response experiment. Lockhart developed a method whereby the degree of bending of pieces of horizontally clamped plant material were recorded in bathing solutions at a wide range of osmotic potentials.…”

Section: Roots In Narrow Air Gaps (L< 3 Mm)mentioning

confidence: 99%

“…Barley and Greacen (1967) proposed that bending moments would be an important characteristic in determining the ability of roots to avoid obstacles in their path. Little direct evidence was given to support this proposal, but it seemed likely from the work of Lockhart (1959) that because root tips are zones of active elongation where rigidity is principally determined by turgor, only small bending moments would be needed to deflect thetn. When soil structure is heterogeneous, the growth and distribution of roots may be greatly affected by whether or not they penetrate or are deflected at interfaces.…”

Section: Introductionmentioning

confidence: 99%

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The buckling of plant roots

Whiteley

Hewitt

Dexter

1982

Physiologia Plantarum

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The mechanical stresses required to buckle root tips were measured directly for seven plant species. For two of these, both seminal and primary lateral roots were measured. For four of the plant species investigated, the easier and more rapid method used to measure the buckling stresses of excised root tips gave results which agree closely with those obtained for the growing roots of intact plants. Values of buckling stress were also calculated from previously determined elastic properties of roots. The calculated and measured values of buckling stress are of the same magnitude only, and comparison for ten root types fails to show any consistent relationship between these two methods. From the results from three plant species it has been possible to define empirical functions to account for the observed changes in root buckling stress with air gap length and water stress. Buckling stresses are not significantly affected by the concentration of nitrate in the growth medium.

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“…The second technique employed was the turgor pressure method described previously (Lockhart, 1959). Twenty mm sections were incubated in mannitol solutions of various concentrations for two hr.…”

Section: Rate Of Equjlibration To a Mechanical Tensile Forcementioning

confidence: 99%