ISHS Acta Horticulturae 187: I International Symposium on Mechanization of Vegetable Production
EFFECT OF TWOFOLD FLAT PLASTIC COVER ON YIELD AND QUALITY OF VEGETABLES |
| Author: | A. Maync |
| Abstract:
While covering early vegetables with single polyethylen sheeting (PE) is standard practise, double sheeting shows further advantages with kohlrabi (2 x PE) and lettuce (spun polypropylen fabric topped with PE). Double sheeting gains another 4 (lettuce) to 6 days (kohlrabi) when applied very early and the upper sheeting is removed in early April. Prolonged cover endangers early harvest and quality, applying to double and single cover as well. Take-off will possibly have to be decided on critical decade mean temperatures. Covering with 1 x PE (4 % holes) gives an extra 2° C, with 2 x PE (each 4 % holes) an extra 4° C on open air mean temperature. Frost protection is limited to about 1,5° C (1 x PE) and 3° C (2 x PE). Maximum shadow temperature difference to open air reached 8° C (1 x PE) and 12° C (2 x PE) respectively. Ground temperature (-10 cm) in sandy soil gains 2,5° C (1 x PE) and 4,5° C (2 x PE) on open air mean temperature, while maximum differences were 4° C and 7° C respectively. | |
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