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Calibration of stem heat balance sensors upon a study of water balance of the hop plantation
- Urban, J., Krofta, K., Kučera, J.
- Acta horticulturae 2012 no.951 pp. 79-86
- Humulus lupulus, energy balance, evapotranspiration, heat, sap flow, transpiration, water balance, water uptake
- Evapotranspiration of the Czech hop cultivar Agnus (Humulus lupulus L.) plantation was investigated during three consecutive growing seasons. We measured two components of the water balance: total evapotranspiration (using the Bowen ratio energy balance method) and transpiration of the bines (using the stem heat balance sensors type EMS SF 62). Actual evapotranspiration peaked when the crop was fully developed, at 80 - 90% of the potential evapotranspiration. Most of the water was evaporated and less than half of the total amount of vaporized water was transpired (the partitioning depended on a stage of crop development). EMS heat balance sensors don’t require any empirical calibration. However, to ensure the correctness of the sap flow measurements, a calibration of the sap flow sensors was performed. Just before the harvest, a total of eighteen bines were removed from the plants and their water uptake was measured potometrically (volumetrically). Accuracy of the sap flow measurement was -3 % when compared against potometry.