Gerbera: maximale isolatie en lichtonderschepping

With the objective of further reducing energy consumption in gerbera cultivation and financed by the program “Greenhouse as Source of Energy” and the Knowledge Cooperation Gerbera, research was conducted from July 2016 to July 2017 at WUR Greenhouse Horticulture in Bleiswijk. In the test, the insulation of the greenhouse was increased by separating the existing 2-layers of the light tight screen, creating an air layer of 5 cm in between them. This improved the temperature layering between the greenhouse and the greenhouse cover, resulting in very low net radiation losses by the crop. The applied light-dependent temperature strategy proved technically and physiologically suitable between November and May. The day length in winter was gradually extended to 13 or 15 hours, with a proportional increase of the average day temperature (at least 16°C) according to the light dependent temperature strategy. This saved some energy on heat, but required more electricity without improving production or quality; on the contrary, the crop showed an increased vegetative growth. All the leaves that intercept light seem to contribute actively to the photosynthesis. As a result, leaf pruning in winter, regardless of the age of the leaf removed, led to a reduced flower production.