Líffræðifélag Íslands
Líffræðiráðstefnan 2015
Erindi/veggspjald / Talk/poster V19
Christina Stadler
Landbúnaðarháskóla Íslands
Kynnir / Presenter: Christina Stadler
Tengiliður / Corresponding author: Christina Stadler (christina@lbhi.is)
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. Therefore, the objective of the study was to test, whether a better red colouring could be reached with LEDs (Light emitting diodes) and how many weeks lighting with LEDs is necessary and when in the growth period this should occur to encourage red colouring together with a suitable yield. In the research greenhouse of the Agricultural University of Iceland were salad seedlings (Lactuca sativa L. cv. Carmoli) grown hydroponically in NFT channels. The salad was either lighted with HPS lamps (400 W, 165 μmol/m2/s) or with LEDs (Fiona lighting, 20 % blue, 164 μmol/m2/s) for 18 h. Some salad plants got only HPS lights during the whole growth period, while others only LEDs. Alternatively, with again other plants was the lighting source changed weekly. Plants were harvested after four weeks with different lighting treatments and quality was investigated and yield measured. The salad had a more intensive red colour when LEDs were used in the last week or even longer. In contrast, when plants got LEDs in the beginning of the growth period and after that HPS lights, was the intensity of the red colour reduced and the salad was partly even less red compared to plants that were lighted with only HPS lamps. A significantly higher fresh yield was achieved with HPS lamps in comparison to LEDs. In contrast, when instead of the only use of HPS lamps the salad got either for one week at the beginning of the growth period or for one or two weeks at the end of the growth period LEDs, was a slightly lower yield measured. In order to achieve a satisfactory red colouring and at the same time a suitable yield of red winter salad it is recommended to lighten with HPS lamps in the first three weeks and with LEDs during the last week.