ISHS Acta Horticulturae 401: International Symposium on Growing Media & Plant Nutrition in Horticulture
WATER BALANCE OF LETTUCE GROWN ON SAND BEDS |
| Authors: | M. Heinen, J. van Moolenbroek |
| Keywords: | closed recirculating cropping system, coarse sand, evaporation, evapotranspiration, Lactuca sativa, substrate, transpiration |
| Abstract:
An experiment was carried out to determine the partitioning of total water use by lettuce grown on sand beds into evaporation and transpiration. One of the available sand beds was covered with a plastic foil, so that its water use was equal to the transpiration, while another plot was left uncovered, so that its water use was equal to transpiration plus evaporation, No differences in fresh and dry matter production were encountered between the covered and uncovered plots, so that the transpiration of the covered plot was regarded to be equal to the transpiration of the uncovered plot. The total amount transpired was 55% of the total water use, while 45% was evaporated. A regression analysis was carried out to relate transpiration data and evaporation data, both corrected for plant size, to global radiation and greenhouse heating. In most cases the cumulative data could be described well based on cumulative radiation data alone. Results from regressions based on limited sets of data could not always be used for extrapolation or interpolation. | |
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