ISHS Acta Horticulturae 176: International Symposium on Protected Cultivations in the Mediterranean Regions
SINGLE AND DOUBLE FLAT COVERING OF CARROTS (DAUCUS CAROTA L.) |
| Authors: | F. Benoit, N. Ceustermans, A. Calus |
| Abstract:
A comparison between the effect of single with double temporary direct cover using ventilated sheeting showed that the single polyethylene sheeting of 50 micron thickness and with 500 perforations of 1 cm in diameter per m2 (PE-500) provided the best results if the sheeting was left on the plants from sowing till the 10th of May, or until the time when the minimum soil temperature 10 cm deep reached 8.5° C. The less favourable resultes obtained with double sheeting were probably caused by temperature stresses which are bound to occur from a maximum temperature of 26° C (average 18° C) resulting in arrest of growth and in ageing symptoms. In this respect we have also pointed out the cumulative effect of reduced translucence (- 34 %) and reduced concentration of CO2 owing to reduction or complete lack of ventilation under the double sheeting. Therefore the sligthly better results with the PE-500-polypropylene (PP) combination were attributed to the slightly lower temperatures (- 1° C) and the higher CO2 concentrations. | |
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