TY - JOUR
T1 - Comparison of xylem flow velocities determined by MRI and a non-invasive heat pulse technique in Golden Alder and Silver Birch
AU - Helfter, C.
AU - Hand, D.
AU - Windt, C.
AU - Van As, H.
AU - Mencuccini, Maurizio
PY - 2007/4
Y1 - 2007/4
N2 - Research is currently under way at Heriot-Watt University (Edinburgh, UK) to develop a robust, portable, non-invasive system for field measurements of xylem and phloem sap flow in trees. The system uses a near-infrared laser source (l = 812 nm) for local application of heat pulses to the stem. The dimensions of the heated area are typically 1 mm high × 5 mm wide; the optical power at the sample is ca. 500 mW and causes a localised temperature rise of 5–10 °C. An infrared camera monitors the temporal evolution of the temperature field around the point of heating; thermometric profiles are used for the calculation of flow velocities. Detection of xylem and phloem by our technique has been demonstrated (Helfter et al.). The performance of the laser-based approach was compared with xylem velocities determined by MRI flow imaging (Windt, etl al.) at the Wageningen NMR Centre (NL). The custom-built MRI system consists of a 0.72 T electromagnet of planar geometry allowing for lateral insertion of the plant and simultaneous MRI and heat pulse measurements. A near 1:1 agreement between MRI and heat pulse xylem flow velocities was found in both Golden Alder and Silver Birch saplings over several night and day cycles.
AB - Research is currently under way at Heriot-Watt University (Edinburgh, UK) to develop a robust, portable, non-invasive system for field measurements of xylem and phloem sap flow in trees. The system uses a near-infrared laser source (l = 812 nm) for local application of heat pulses to the stem. The dimensions of the heated area are typically 1 mm high × 5 mm wide; the optical power at the sample is ca. 500 mW and causes a localised temperature rise of 5–10 °C. An infrared camera monitors the temporal evolution of the temperature field around the point of heating; thermometric profiles are used for the calculation of flow velocities. Detection of xylem and phloem by our technique has been demonstrated (Helfter et al.). The performance of the laser-based approach was compared with xylem velocities determined by MRI flow imaging (Windt, etl al.) at the Wageningen NMR Centre (NL). The custom-built MRI system consists of a 0.72 T electromagnet of planar geometry allowing for lateral insertion of the plant and simultaneous MRI and heat pulse measurements. A near 1:1 agreement between MRI and heat pulse xylem flow velocities was found in both Golden Alder and Silver Birch saplings over several night and day cycles.
U2 - 10.1016/j.cbpa.2007.01.064
DO - 10.1016/j.cbpa.2007.01.064
M3 - Article
SN - 1095-6433
VL - 146
SP - S268-S269
JO - Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology
JF - Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology
IS - 4, Supplement
ER -