The greenhouse horticulture sector and the government have jointly committed to cultivating in a fossil-free manner by 2040. To achieve this, two paths are necessary: which alternative energy sources are available and how can energy consumption be reduced. Wageningen University & Research BU Glastuinbouw is researching so-called low-chill strawberries. These offer the possibility to adjust the climate strategy and thereby reduce energy consumption. Researcher Johanna Bac-Molenaar: "Energy savings are certainly possible in the cultivation of low-chill strawberries."
A year-round illuminated strawberry cultivation uses a lot of energy during the growing season. In unilluminated low-chill strawberry cultivation, energy is mainly needed during the first three months when the plant is developing, and the clusters formed in the tray field are maturing. WUR researched two of these varieties: Inspire & Fandango. The aim of the research was to cultivate with low energy and CO2 input.
In the research, the greenhouse was not ventilated at the end of the day, allowing the temperature to drop slowly, partly due to the use of closed screens: a transparent energy screen and an aluminum curtain. During the day, the energy screen was closed when heat was needed, which, combined with active dehumidification, created a stable climate.
Significant energy savings
The production with this cultivation method was good. Just as important: the energy savings were significant. However, mildew pressure increased towards the summer as the windows were opened more frequently, and moisture levels in the greenhouse rose during humid nights.
Bac-Molenaar: "Energy savings are indeed possible in low-chill strawberry cultivation. However, the intensive use of the energy screen during the dark months does block some light, resulting in slower crop development. Placing CO2 dosing tubes in the crop is only locally beneficial when windows are open. The concentration is higher only near the dosing hole of the pure CO2. Shortening daylight hours can extend the cluster induction period as long as daily temperatures do not rise too much."
The research is a Kas als Energiebron project and also receives financial support from the Strawberry Research Foundation. The screen is sponsored by Ludvig Svensson.