Klimaat, energieverbruik en bloem temperatuur bij twee Gerbera telers: als onderdeel van het monitoringsproject

This report provides an overview of the Gerbera companies -Holstein Flowers and Zuijderwijk Witzier. Both growers have a blackout screen, energy screen and an illumination system. Holstein Flowers dehumidifies the greenhouse air by means of blowing in heated outside air (using air ducts) and Zuijderwijk Witzier uses a Ventilation Jet system. Both growers screen a lot using a screen gap and they close very rare the screens for 100%. At Holstein Flowers the calculated energy consumption is 22.7 m3/m2/year and at Zuijderwijk 23.8 m3/ m2/year. With a thermal camera, the crop and flower temperatures were measured and they were rarely below the dew point. By carrying out plant sap analyses at 4 growers, a statistical relationship between the plant sap composition and the chance of rot heads (‘rotkoppen’) has been demonstrated. However, it is unknown whether this relationship is also a causal relationship, other factors could also have caused the rot heads. If the mechanism behind the development of Botrytis/rot heads were known, then a grower could - depending on the plant balance, evaporation and the chance of getting Botrytis/rot heads –grow with lower moisture deficits, which could then lead to energy savings