This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (89) Citing Articles via Google Scholar Google Scholar Articles by Fiscus, E. L. Search for Related Content PubMed PubMed Citation Articles by Fiscus, E. L. Agricola Articles by Fiscus, E. L.

Articles

Determination of Hydraulic and Osmotic Properties of Soybean Root Systems ¹

^a Department of Botany, Duke University, Durham, North Carolina 27706

An analytical technique which allows the experimental determination of soybean (Glycine max L.) root properties is presented. Two major problems hamper the interpretation of experimental data. These are: (a) the influence of a possible boundary layer which raises the effective value of ° above that of the bulk solution; and (b) the difficulty of obtaining an adequate measure of the internal osmotic pressure except at high values of volume flow rate due primarily to possible exchanges of solutes between the xylem and adjacent tissues. Consideration of these two problems leads to an interpretation of previous models which is reconcilable with the criticisms of Newman (Plant Physiology 1975 57: 738-739).

In these experiments, estimates of hydraulic conductivity and reflection coefficient are based on high flow rate data where the osmotic effects are minimized. Because of the difficulties attached to the evaluation of ⁱ, at low and moderate flow rates, any technique for evaluating root parameters which depends on knowledge of when the osmotic pressure difference (in bars) is zero will be subject to large errors, at least until both problems metioned above have been adequately resolved.

An additional problem which must be dealt with in terminal root segments is the effect of a standing osmotic gradient. It is thought that this is not a serious problem in a complex root system.

Transpiration rates are calculated on the basis of leaf and root surface areas and experimentally determined root volume flow. It is shown that root flow rates necessary to sustain high transpiration rates in the shoots are easily accommodated by the model at moderate levels of applied pressure difference.

¹ Research supported by National Science Foundation Grant No. BMS71-01193 A04 to P. J. Kramer, Duke University.

This article has been cited by other articles:

				L. A. Cernusak, K. Winter, and B. L. Turner Plant {delta}15N Correlates with the Transpiration Efficiency of Nitrogen Acquisition in Tropical Trees Plant Physiology, November 1, 2009; 151(3): 1667 - 1676. [Abstract] [Full Text] [PDF]

				T. Knipfer and E. Steudle Root hydraulic conductivity measured by pressure clamp is substantially affected by internal unstirred layers J. Exp. Bot., May 1, 2008; 59(8): 2071 - 2084. [Abstract] [Full Text] [PDF]

				S. H. Lee, G. C. Chung, and E. Steudle Gating of aquaporins by low temperature in roots of chilling-sensitive cucumber and chilling-tolerant figleaf gourd J. Exp. Bot., March 1, 2005; 56(413): 985 - 995. [Abstract] [Full Text] [PDF]

				J. Melkonian, L.-X. Yu, and T. L. Setter Chilling responses of maize (Zea mays L.) seedlings: root hydraulic conductance, abscisic acid, and stomatal conductance J. Exp. Bot., August 1, 2004; 55(403): 1751 - 1760. [Abstract] [Full Text] [PDF]

				X. Wan and J. J. Zwiazek Mercuric Chloride Effects on Root Water Transport in Aspen Seedlings Plant Physiology, November 1, 1999; 121(3): 939 - 946. [Abstract] [Full Text]