Resumen
- In the Horticultural Research Centre, located 20 km to the North of Bogota, three plastic greenhouses were built, each covering an area of 1100 m2, and provided with a computerized climate registration system. The three greenhouses are: a 'traditional' Colombian greenhouse with a fixed open ridge and side walls that can be opened manually; a greenhouse with an automated roof ventilation system and a polyethylene (PE) climate screen; and a retractable roof greenhouse with an ILS thermal screen and heating by gas combustion. In half of each of the greenhouses roses were planted. In a first phase, the climate generated in the greenhouses was evaluated. The plastic greenhouse with the automated roof ventilation creates a more stable and uniform climate regime during the day, in comparison with the traditional greenhouse. During the night, this greenhouse is 1°C warmer than the traditional greenhouse, while the air humidity is higher. When the PE climate screen is used the mean average night temperature increases with 2 additional degrees, while the highest difference in minimum temperature between this greenhouse and the outside was of 4.8°C. An earlier study showed that the climate screen improves the night temperature of a traditional greenhouse by an average 2°C and that this difference increases as the night temperature goes lower. An advantage of the retractable roof greenhouse is the better radiation regime inside. On the other hand, during the trial this greenhouse had a relatively low day temperature, while during the night the average temperature was almost 0.7°C lower than the plastic greenhouse with automated roof ventilation. Humidity under the thermal screen was always lower than under the PE screen which has condense water on the screen at daybreak.