What must be considered in winter strawberry production under LEDs in Iceland?

ABSTRACT

Supplementary lighting is essential to maintain year-round production in Iceland due to the extremely low natural light level in winter. In this research, the effects of high-pressure vapour sodium lamps (HPS) are compared to light emitting diodes (LED), both with similar photosynthetic photon flux density (PPFD). Strawberries (Fragaria x ananassa cv. ‘Sonata' and cv. ‘Magnum') were grown either under HPS lights or LEDs and 16°C/8°C (day/night). However, in the second winter, the day temperature was increased to 19°C under LEDs. The results showed that under the same temperature set points, the development of the flowers and the harvest was delayed by two weeks under LEDs due to a lower leaf, substrate and air temperature. However, when temperature set points were adapted, no delay under LEDs was observed. LEDs did not lead to higher yield, but to a higher energy use efficiency, while light use efficiency behaved contrary. Economic calculations clearly demonstrate that it is not justified to switch from HPS lights to LEDs. Instead, it is rather recommended to emphasise a high-yielding variety like Sonata in winter-growing of strawberries.

KEYWORDS:

• Fragaria x ananassa
• light sources
• supplemental lighting
• temperature settings
• year-round greenhouse production

Disclosure statement

No potential conflict of interest was reported by the author.

Declaration of interest statement

The author reports there are no competing interests to declare.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by Framleiðnisjóður landbúnaðarins and Samband garðyrkjubænda.

Notes on contributors

Christina Stadler

Christina Stadler is an assistant professor at the Agricultural University of Iceland. Her work focused on greenhouse experiments with supplemental lighting, optimisation of yield and production costs besides experiments with fertilisers for organic production.