On-line Estimation of the Rate of Sap Flow in Plant Stems Using Stationary Thermal Response Data

Zee, G.A. van; Schurer, K.

doi:10.1093/jxb/34.12.1636

Cited by 8 publications

(3 citation statements)

References 2 publications

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“…Heat pulse (4,8,9,25), stem heat balance (6, 21) and magnetohydrodynamic (22) methods, hitherto, have been employed for the studies of the transpiration stream, and the aspects of the stream have been observed in relation to the leaf transpiration. For adequate analysis of water balance in the plant, it is further necessary to measure directly the water flux (mass of flowing water per unit time) in the intact stem in course of time: the on-line measurement of the water flux in the stem could contribute to the examination of dynamic characteristics ofthe transpiration stream relating to the leaf transpiration and the root water absorption.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Analysis of Transpiration Stream Dynamics in an Intact Cucumber Stem by a Heat Flux Control Method

Kitano¹,

Eguchi²

1989

Plant Physiol.

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Water flux of transpiration stream in an intact stem of the 10 leaf stage cucumber plant (Cucumis sativus L. cv. Chojitsu-Ochiai) was measured by a novel system of heat flux control method with a resolution of 1 x 10-3 grams per second and a time constant of 1 minute; two heat flux control sensors were attached to the seventh intemode and the stem base. The transpiration stream responded clearly to leaf transpiration and root water absorption when the plant was exposed to light, and the water flux at the stem base corresponded to the transpiration rate per plant in steady state. Root water absorption lagged about 10 minutes behind leaf transpiration. Dynamics of water fluxes were affected by the lag of water absorption in roots, and temporary water loss caused by rapid increase in leaf transpiration was buffered by about 5% of the water content in the stem.The transpiration stream in the stem is located between transpiration in leaves and water absorption in roots, and can be considered as an essential component of the water balance in the plant. Heat pulse (4,8,9,25), stem heat balance (6, 21) and magnetohydrodynamic (22) methods, hitherto, have been employed for the studies of the transpiration stream, and the aspects of the stream have been observed in relation to the leaf transpiration. For adequate analysis of water balance in the plant, it is further necessary to measure directly the water flux (mass of flowing water per unit time) in the intact stem in course of time: the on-line measurement of the water flux in the stem could contribute to the examination of dynamic characteristics ofthe transpiration stream relating to the leaf transpiration and the root water absorption. We have developed a novel system (12), HFC,' for on-line measurement of the water flux in the intact stem in real time without the need for any calibrations. The present paper deals with the application of the HFC system to the analyses oftranspiration stream dynamics by using two HFC sensors attached to the upper stem and the stem base of an intact cucumber plant, aiming at better understanding of water balance in a plant. MATERIALS AND METHODS HFC MethodThe HFC method is based on the heat balance with control of the heat fluxes from a heater attached to the intact stem 'Abbreviation: HFC, heat flux control.surface. Figure 1 shows

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Section: Introductionmentioning

confidence: 99%

Quantitative Analysis of Transpiration Stream Dynamics in an Intact Cucumber Stem by a Heat Flux Control Method

Kitano¹,

Eguchi²

1989

Plant Physiol.

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“…Several heat-pulse (Huber and Schmidt 1937;Closs 1958;Marshall 1958;Swanson 1972;Cohen et al 1981;Green and Clothier 1988) and steadystate heating methods (Saddler and Pitman 1970;Sakuratani 1981;van Zee and Schurer 1983;Schulze et al 1985;Baker and van Bavel 1987) have been used for the non-destructive estimation of sap-flow rates in plants.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of various heat-pulse methods for estimation of sap flow in orchard trees: comparison with micrometeorological estimates of evaporation

Jones¹,

Hamer²,

Higgs³

1988

Trees

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Summary.A microcomputer-controlled heat-pulse system for the measurement of sap velocity in trees is described. Several published methods for determining sap velocity from the temperature rise measured either above or below a heater inserted into the stem were compared and evaluated. All methods could be improved by the use of curve-fitting procedures, with a particularly useful approach involving direct estimation of the parameters of the diffusion equation using the non-linear curve-fitting package maximum likelihood programme. An alternative approach that was based on measurement of the value of the maximum temperature was proposed and tested. This was found to be particularly robust and sensitive to changes in flow rate. Although sap-flow velocity varied markedly with depth in the stem (as shown by the rate of dye movement), the maximum temperature at any given flow rate was found to be relatively insensitive to sensor depth. Estimated sap-flow velocities were compared with evaporation rates estimated either by weighing (for potted trees) or by the Penman-Monteith equation. Several independent methods were used for estimating the values of boundary layer resistance and net radiation that were required for application of the Penman-Monteith equation. There was a close relationship between flow and evaporation with some evidence for hysteresis. Although absolute calibration of the sap-flow estimates is difficult, the methods described are all useful for relative studies and all responded rapidly to altered flow rates caused by changing weather conditions. Offprint requests to: H. G. Jones

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“…In this experiment the two sensor responses are related precisely by the transfer function of the flow process considered, i.e., the flow process between the sensors (Levenspiel and Bischoff, 1963). The transfer function does not include the dynamics of the source and the sensors (Van Zee and Schurer, 1983). Further, the source may be artificial or natural and the source signal need not be known because it is not used.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the transfer function, time moments, and model parameters of a flow process

1987

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On-line Estimation of the Rate of Sap Flow in Plant Stems Using Stationary Thermal Response Data

Cited by 8 publications

References 2 publications

Quantitative Analysis of Transpiration Stream Dynamics in an Intact Cucumber Stem by a Heat Flux Control Method

Quantitative Analysis of Transpiration Stream Dynamics in an Intact Cucumber Stem by a Heat Flux Control Method

Evaluation of various heat-pulse methods for estimation of sap flow in orchard trees: comparison with micrometeorological estimates of evaporation

Estimation of the transfer function, time moments, and model parameters of a flow process

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