STEM SAP FLOW, MEASURED USING PROTON NUCLEAR MAGNETIC RESONANCE, IN COMPARISON WITH TRANSPIRATION AND WATER UPTAKE OF CUCUMBER IN A GREENHOUSE CLIMATE

A portable NMR spectrometer, developed at the Dept. of Molecular Physics of the Wageningen Agricultural University, was used to study the diurnal course of stem sap flow rate of cucumber in a crop in a greenhouse environment and to consider its possible application in a climate control system.
Stem sap flow rate was compared with plant transpiration and water uptake rate, using a lysimeter and potometer.
Stem sap flow was measured at the base of the shoot.
At night the stem sap flow rate was within 10 % of the water uptake rate, both being higher than transpiration rate, because of water uptake for growth.
The short term fluctuation of stem sap flow rate at night resembled that of transpiration rate.
Around midday it followed the fluctuation in global radiation instantaneously.
It is concluded, that results so far look promising, but that additional validation of the accuracy of the measurement as a valuation of momentary stem sap flow is needed.
The NMR spectrometer is useful for understanding and quantification of internal plant water relations.

I International Workshop on Sensors in Horticulture

P.A.C.M. van de Sanden, J.E.A. Reinders, P.A. de Jager, H. van As

https://doi.org/10.17660/ActaHortic.1992.304.26