Evaluation of different lighting sources on the growth and chemical composition of lettuce

D. Sergejeva¹, I. Alsina¹*, M. Duma², L. Dubova¹, I. Augspole², I. Erdberga¹ and K. Berzina³

¹Latvia University of Life Sciences and Technologies, Faculty of Agriculture, Institute of Plant and Soil Science, Liela street 2, LV-3001 Jelgava, Latvia
²Latvia University of Life Sciences and Technologies, Faculty of Food Technology, Department of Chemistry, Liela street 2, LV-3001 Jelgava, Latvia
³Riga Technical University, Faculty of Power and Electrical Engineering, Kalku street 1, LV-1050 Riga, Latvia
*Correspondence: ina.alsina@llu.lv

Abstract:

Experiment were carried out in Latvia University of Agriculture in plant growth room. Lettuce Lactuca sativa L. var foliosum cv. ‘Dubacek’ and L .sativa L. cv. ‘Michalina’ were grown under 4 types of lights (luminescence lamps, commercial light emitting diodes (LED) lamps (V-TAC premium series – for plant growing) and two different Lumigrow LED strips – dominant wavelength- blue or red with 14 h photoperiod and total photosynthetic active radiation (PAR) 100 μmol m^-2 s^-1 in all variants. Plant weight, length, amount of leaves were measured. Content of chlorophylls, carotenoids, phenols, flavonoids in lettuce was determined three times per vegetation period. In experiments were found that higher lettuce yield was under commercial LED (V-TAC premium series), but these plants contain less soluble sugars, pigments and phenols. Better plant quality was obtained with luminescence lamps. These lettuces have higher sugar, phenols and flavonoids content. Lettuce growth under blue dominate LED (LEDb) was delayed, but these plants contain higher chlorophylls content. The differences in plant growth, response to light and biochemical content between cultivars were detected.

Key words:

flavonoids, Lactuca sativa, LED lamps, phenols, Pigments

Research of parameters of light emitting diode lamps and their suitability for lighting of working areas

J. Paju

Tallinn University of Technology, Ehitajate 5, EE19086 Tallinn, Estonia;e-mail: jana.paju@ttu.ee

Abstract:

The current paper describes the results obtained during several experiments inTallinn University and Tallinn University of Technology considering the parameters of lightemitting diode (LED) lamps. Four different LED lamps were investigated, all of them defined(by vendors and/or manufacturers) fitting to replace a 60 W incandescent lamp. The lampsinvestigated were the only ones fitting the definition and possible to purchase from vendors inTallinn, Estonia in the beginning of year 2012, when the experiments were carried out. Severalmethods were used to determine parameters such as: working temperature of luminaires,illuminance, working power, the spectrum of created light, the flicker produced. According tothe results of flickering, frequency and the modulation index of the flickering were calculated.The purpose of the research was to draw conclusions concerning the hypothesis, that byreplacing a 60 W incandescent lamp (IL) with a fitting LED lamp, the lamp that uses lesselectrical power is equivalent to the previously popular IL by the spectral properties as well asthe produced illuminance. Conclusions were also drawn considering the influence of such lighton people exposed to it. Key words: LED lamps, working temperature of luminaires, illuminance, working power ofluminaires, spectrum of light, flickering of light, occupational health, colour rendering index.

Key words: