In situ plant water balance studies using a portable NMR spectrometer
1994
As, H. van | Reinders, J.E.A. | Jager, P.A. de | Sanden, P.A.C.M. van de | Schaafsma, T.J.
A portable 1H NMR spectrometer has been applied to whole plants in situ, i.e. in climate rooms and in a greenhouse, to study plant water relations under these conditions. The spectrometer consists of a 30 kg permanent magnet system of 0.235 T, modified Bruker Minispec electronics, and a standard XT pc for spectrometer control. Unattended, the system automatically measures the xylem sap stream and tissue water content in a well-defined section of the plant stem. Because of the small size of the magnet these measurements can be made at different positions on the plant stem or on different plants in succession. Magnetic field drift due to the varying climates that occur in greenhouses was corrected by field locking. Results are presented for a single plant in a climate room, demonstrating a method for the study of plant water hydraulics. In addition, a single plant in a greenhouse crop was measured, and the NMR results were compared with the water uptake and transpiration rates under (natural) variation of light intensity and relative humidity, demonstrating the reliability of the portable NMR under realistic greenhouse conditions. Finally, the application for the measurement of the root water uptake efficiency is demonstrated for a number of grafted cucumber plants under constant climatic conditions in a phytotron.
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