Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2023
Höfundar / Authors: Christina Stadler
Starfsvettvangur / Affiliations: Agricultural University of Iceland
Kynnir / Presenter: Christina Stadler
Growers in Iceland have adopted intensive use of supplementary lighting to maintain year-round production. The objective was to test if the light source, high-pressure vapour sodium lamps (HPS) or light emitting diodes (LED), is affecting production of seedlings.
In the research greenhouse of the Agricultural University of Iceland were tomato, sweet pepper and cucumber transplants grown under HPS lights or LEDs with 230 µmol/m2/s for 18 hours.
Substrate and leaf temperature was significantly higher under HPS lights. Transplants were lower under LEDs. Seedlings of cucumbers had a significantly higher stem diameter, fresh and dry biomass yield under HPS lights, whereas these parameters were not significant different between light sources for seedlings of tomatoes and sweet pepper. The number of leaves of tomatoes and cucumbers was independent of the light source. This was also observed for sweet pepper before the division of the stem into two tops, but after that was the number of leaves significantly increased by LEDs.
Using LEDs was associated with 15% lower usage of kWh’s, but nearly three times higher investment costs, resulting in higher total light related costs. The energy use efficiency was independent of the light source for cucumbers, whereas for tomatoes and sweet pepper was light better transferred into yield under LEDs.
It is not recommended to grow seedlings that require later a high wire culture only under LEDs.