Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2017

Erindi/veggspjald / Talk/poster V66

Effect of different LED lighting treatments on reddening and yield of red winter salad in Iceland

Höfundar / Authors: Christina Stadler

Starfsvettvangur / Affiliations: Landbúnaðarháskóla Íslands

Kynnir / Presenter: Christina Stadler

The extremely low natural light level is the major limiting factor for winter glasshouse production in Iceland. Therefore, supplementary lighting is essential to maintain year-round production. So far, salad is lighted with high-pressure vapour sodium lamps (HPS). However, in winter is the problem that red salad is not adopting the characteristic red colour. From previous experiments it is known that salad had a more intensive red colour when in the last week of the growth period or even longer LEDs (Light emitting diodes) were used. However, with HPS was achieved a significantly higher fresh yield in comparison to LEDs. Therefore, it should be tested if it is possible to get a satisfactory reddening and at the same time a suitable yield by using either a higher μmol/m²/s with LEDs than with HPS lamps or by using LEDs and HPS lamps together in comparison to the single application of HPS lamps.
In the research greenhouse of the Agricultural University of Iceland were salad seedlings (Lactuca sativa L. cv. Carmoli) grown hydroponically in NFT channels. In the first experiment was the salad either lighted with HPS lamps or with LEDs (Fiona lighting, 20% blue). The μmol/m²/s was 27% higher and the day temperature one degree higher in the LED chamber compared to the HPS chamber. In the second experiment was the salad either lighted with only HPS lamps or with HPS lamps and LEDs together. The level of the μmol/m²/s and the temperatures were the same in both lighting treatments. Light was applied for 18 h (05.00-23.00) in both experiments. Plants were harvested after four weeks and quality investigated and yield measured.
The salad had a more intensive red colour when LEDs were used instead of HPS lamps. When salad was grown under HPS lamps and LEDs together, was the colour of the salad still more red compared to only under HPS lamps grown salad. Despite of the lower day temperature and the lower µmol/m²/s-level in the HPS treatment compared to the LED treatment, was a significantly higher fresh yield achieved with HPS lamps. In contrast, when instead of the only use of HPS lamps the salad was grown under HPS lamps and LEDs together, was a slightly lower yield measured.
It seems that a satisfactory colouring and at the same time a suitable yield is not possible with lighting with HPS lamps and / or LEDs.