Low chill strawberries: Long picking season with low energy input

ABSTRACT In two sequential years, we showed in a 450 m 2 greenhouse in Bleiswijk (the Netherlands) that low chill strawberry can be grown with low energy and CO 2 input. The ETFE greenhouse cover provided high transmission of diffused light. With a swinging gutter system, the distance between the plant rows was kept lower, causing a higher plant density. Maximal insulation by intensive use of screens prevented heat loss. Especially a lot of energy was saved by closing the windows and screens at the end of the day instead of opening them to come fast to a low night temperature. We even showed that if the heat from the dehumidification in summer could be stored in a seasonal buffer to be used in winter, we could grow low-chill strawberries energy neutral by only input of ‘green’ electricity. Day length reduction resulted in a prolonged picking season, but prolongation till autumn with high yield was not possible with 12-h day length for both of the used varieties Inspire and Fandango. Powdery mildew control on the fruit was a challenge in such a long picking season and needs attention in new research projects. Significance of the study What is already known on this subject? Strawberry production in greenhouses is much higher than in open field because growing conditions are optimized and growing seasons are shifted. Because of that, the acreage of protected strawberry crops in the Netherlands did increase from 255 ha in 2010 to 602 ha in 2024 (CBS). To realize the high production potential input of energy and CO2 is needed. For several greenhouse crops it is shown that energy and CO2 input can be reduced by smart climate control, insulation and dehumidification. What are the new findings? Low chill strawberry varieties fit well in a sustainable production system in which heat input, and therefore CO2 emission, is reduced. They perform well at relatively high night temperatures. Therefore less energy is needed to heat the greenhouse in the morning. In two sequential years we showed that we could produce low chill strawberries with much lower energy and CO2 input than what is common in practice. In addition, we have found that reducing the daylength stimulates flower induction in spring and early summer, resulting in elongation of the picking period till end of August. What are the expected impacts on horticulture? Sustainability will become more and more important for horticultural sector because governments, society and consumers demands. This research shows that strawberry sector can meet these sustainability demands by cultivar choice, smart climate control, and greenhouses that are equipped with insulation screens and active dehumidification systems.