The yield of lettuce breeding line under led lamps in winter greenhouse in the North

The lettuce (Lactuca sativa L.) is widely known and favorite vegetable crop among people. In Europe the main production of lettuce is performed on protected ground with application of artificial light sources. The artificially-lighted culture of salad became very actually acquired in the north. Previously, on the basis of multi-year studies on yield registration and experiments with different regimes of lighting we have defined the appropriate parameters of supplementary lighting for lettuce with sodium high-pressure lamps that provided the production in different seasons per year. The aim was to study the accumulation of biomass and yield quality in lettuce ‘Aphytsion’ being grown in winter rotation under light-emitting diodes lamps. The accumulation of biomass and yield quality was studied in ‘Aphytsion’, grown in winter rotation under light- emitting diodes lamps ECOLED-BIO-112-185W-D120 UniversaLED (ООО ‘GK’ ‘CET’), Perm, in industrial greenhouse OOO ‘Prigorodniy’ at Syktyvkar city. The commodity output was obtained for two cycle of cultivation, November-December and December-January. Yield of foliage biomass was 2.4 kg/m2 with flow density PAR (Photosynthetically active radiation) about 90 μmole quantum/m2 s. at 20 W/m2 with total light energy 54 MJ/m2 supplied to plants from LED lamps. The plants produced about 0.5 g. of dry weight calculated on one mole of spent light energy. Energy efficiency of PAR was 3% that corresponded with data observed earlier with sodium high-pressure lamps. The conclusion was made about the suitableness of this type of light-emitting diode lamps for lettuce cultivation in winter rotation in first photic zone. It was recommended to increase duration of supplemental lighting up to 22-24 hours in December and up to 20-22 hours in January to improve the productivity and biological value of plant output. It enables to raise RAP income in plants by 35 %, on average for one cycle of cultivation.