Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 477640
Title Estimation of available water and evapotranspiration of potted plants with a frequency-domain sensor
Author(s) Baas, R.; Bulle, A.A.E.; Vonk Noordegraaf, C.
Source In: International Symposium on Growing Media and Hydroponics. - Leuven : ISHS - ISBN 9789066055377 - p. 291 - 297.
Event Leuven : ISHS - ISBN 9789066055377 International Symposium on Growing Media and Hydroponics 2004, Alnarp, 2004-06-15/2004-06-16
Department(s) Wageningen UR Greenhouse Horticulture
Nursery Stock
Publication type Contribution in proceedings
Publication year 2004
Abstract The relation between volume fraction water () of different peat-based growing media and permittivity (or dielectric constant, ) was determined using a frequency-domain (FD) sensor. After calibration in two organic mixes, could be estimated in rooted mixes in pot volumes ranging from 0.5 to 4 liter. Marketable plants had a within the range 0.5-0.65 after a subirrigation period of 10 minutes ( at capacity). Wilting point was at 0.12-0.20 for the potted ornamental plants Spathiphyllum, Chrysanthemum, Chamaecyparis and Viburnum. With the use of FD measurements, evapotranspiration of potted plants was determined under different transport and consumer conditions. Evapotranspiration varied between 7 and 91 g pot-1 day-1 for the crops. By dividing the amount of available water (derived from pot volume and difference between at capacity and at wilting point) with evapotranspiration data, potential transport time of potted plants was estimated to be at least 8 days. Both increased relative humidity (70 versus 40%) and decreased temperature (5 versus 15°C) decreased evapotranspiration during transport simulation up to 50%. Given the standard deviation in of 0.03-0.06 and desired accuracy (e.g. 0.05) it was calculated that 7-23 pots had to be measured in order to obtain a reliable sample estimation of water content. Application of the FD-sensor include quality control in the grower-retailer-consumer chain and on-line feed-back irrigation control
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